CA2051498A1 - Process for treatment of aqueous solutions of polyhydric alcohols - Google Patents

Abstract

PROCESS FOR TREATMENT OF AQUEOUS SOLUTIONS
OF POLYHYDRIC ALCOHOIC

ABSTRACT

The process relates to the treatment of aqueous solutions of polyhydric alcohols to remove heavy metal components, oils, organic contaminants and, optionally, water. The process is particularly well suited for use in the treatment of spent antifreeze/coolant from the cooling systems of internal combustion engines.

Description

{~ ~' 228~Z
PROCESS Fo~ TR~A~MEN~ OF AQUEOUS SO W TIONS
OF POLYHYDRIC ALCOHO~S
FIELD OF THE INVENTION:
The in~tant invention relates to a procecs for the treatment of aqueou6 601utions of polyhydric alcohols, e.g. ethylene glycol, containing contaminant(s), particularly a heavy metal 6uch as lead, copper, iron, zinc and non-heavy metals such as aluminum. The instant invention is particularly useful in treatment of an antifreeze/coolant removed from heat exchange 6y~tems, including those of automobiles and trucks.

INFORMATION DISCLOSURE STATEMENT:
Considerable interest has been associated with the purification of numerous polyhydric alcohols in relation to their manufacture. In particular, the purification of aqueous ethylene glycol has received coneiderable attention owing to the commercial significance of ethylene glycol in the manufacture of polyester U.S. Patent No. 3,732,320 discloses a purification process for reducing the iron content of ethylene glycol from an ethylene glycol manufacturinq process. The process involves contacting ethylene glycol with a cation exchange resin in the acid cycle.
~lthough the removal of iron wa6 o~ primary concern to the patentee, the patentee generally ~tates that niron ~nd other metallic contaminants present in trace amounts~ may be removed by the cation exchange treatment.
U.S. Patent No. 4,118,582 di6closes a recovery process for removing dissolved antimony catalyst from unreacted ethylene glycol recovered from the manufacture o polyester. The recovery process involve6 a p~ adjustment of the spent glycol to about ~J~ ~ ;3i ~ ~fj 2 to 7, reaction with an alkali ~etal borohydride to form a metallic antimony precipitate, s~paration of the ~etallic Anti~ony pr~cipitate from the ~pent glycol tunreacted e~hylene glycol from the ~anufacture of polyester) in the ~bsence of oxygen, followed by di~tillation o~ ethylene qlycol from the spe~t glycol.
U.S. Patent No. 4,260,827 disclo~es a proces6 for the purification of aqueou6 ~olutions of low ~olecul~r weight polyhydroxyl compound~. The patentee'~ proce66 i~ directed to the purification of low molecular weight polyhydroxyl compound6 after their manufacture in the presence of catalyst6 containing calcium and/or lead. The patentee' 8 process involves numerous treatment and distillation 6teps. The aqueous solution of the low molecular weight polyhydroxyl compound i6 first treated with methanol and a precipitant to form a precipitate to be ~eparated from residual solution. The pH of the ~ethanol/precipitant ~olution of low molecular weight polyhydroxyl compounds may be adjusted to a pH from 1 to 4 to maximize precipitation of the calcium and/or lead compounds from th~ methanol treated solution.
The deposits (precipitates) are removed by filtration nnd the residual solution treated with a cation ~
~xchanger. The residual ~olution is then distilled to remove low-boiling fractions. The distillation sump essentially containlng the low molecular weight polyhydroxyl conpounds i6 then treated with an anion exchanger.
The above processe~ h~ve been directed to ~anu~acturing processes where a ~anufactured product i8 beinq puri~ied or where there is a need to purify and recover unreacted raw ~aterial6 from ~pecific reagents present as a result of co~mercial proces6es.
Such processe6 deal with purification o~ compositions f ) ~ r~

wit~ li~ited and well under6tood cont~min~nt~.
The purification of ~ore ethylene glycol-containing ~tream~ from automotive cooling ~ystem~
r~i6e~ ~ignificantly more complex que~tion~ a8 to the contamin~nts to be removed by treatment. For ~xa~ple, the purification of ~ spent ant~freeze/coolant ~ a dramatically different treatmen~ proces~ owing to the novel and har~h environment to which the antifreeze/coolant ha6 been sub~ected and, further, owing to the ~pecific and unigue chemical components commonly present in the ~pent antifreeze~cool~nt to be treated. Owing to the complexities a6socia~ed with treating a 6pent antifreeze/coolant it i~ not urprising that few attempts have been made to tre~t ~pent antifreeze/coolant solutions.
U.S. Patent No. 4,791,890 di~closes a flushing process (employing ~ flushing liquid having entrained ga~ bubbles) for an ~utomotive cooling sy6te~ wherein t~e patentee includes a filtering 6tep (at 302). The patentee provides no other treat~ent of the ~pent antifreeze coolant. U.S. Patent No. 4,793,403 -disclose~ a coolant ~ystem for use in treatment of coolant liquid. The liguid coolznt is treated by filtering to remove contaminant from the cool~n~
liquid. The patentee discusses a chemical treatment at column 3, lines 11 to 28, but only in vague terms and only by addition of chemical components prev~ou61y pre ent in the ori~inal antifreeze/coolant, ~.e., addition of new additive~. The patentee disclose~
re~oval of particulate and congealed ~ub6tances through a filter (28) followed by treatment of agueou~
liquid by addition of chemical ~gent or agents. The patentee doe6 not disclo6e any particular treatment, merely alluding to the fact that ~uch che~ical6 c~n ~nclude corrosion inhi~itor, i.e., anti-ru6t compound, pH adjustment chemical~, and fresh ~ntifreeze compound tglycol, for example). In ~dditicn, at column 3, linQs 38 to 48, filter 41 ~ay contain ~metal powder~
to prov~de ~et~ll$c lons for ~eutralizing electrical charge. Similarly, Kleer-Flo Company has p~bli~hed the det~ils of k antifreeze recycle ~chine (Kleer-Flo AF 250 Anti-Freeze Recycler) whi~h ~mploy~ 8 three step filtration ~ystem which employ~ A
stainless steel ~cr~en filter, a pr~-filter for removing ~aterials down to a size of 5 ~icronC and A
third filter alleged to remove impurities at the molecular level (approximately 50 Angsto~s). After filtration the filtered antifreeze is mixed with an additive package to provide a working antifreeze for reintroduction into an Automotive cooling 6ystem. No che~ical removal process i5 disclosed whereby the purification of the spent antifreeze/coolant i6 achieved.
The above discussion of the prior art demonstrate~ the failure of the prior art to disclose An effective process for the p~rification of used ethylene glycol-based heat exchan~e fluids, particul~rly used ~pent ~ntifreeze/coolant from automotive cooling systems. It is particularly useful to note the lack of effective treatment steps of the spent antifreezeJcoolant in U.S~ Patent No. 4,793,403 and by the Kleer-Flo~ AF 250 Anti-Freeze Recycler for contaminants ~uch as heavy metals and organic compounds other than ethylene qlycol. Further, such proceæses ~peciically warn ~gain6t their use when the spent antifreeze/coolant to be treated contains an oil co~ponent. Such a limitation of use &ignificantly detracts from the co~mercial use of ~uch processes.

~UMMARY OF THE INVEN~IQ~:
The instant process relates to the treatment of ~queous polyhydric alcohol-containing compositions.

D-lS600 i X

In one embodiment the polyhydric alcohol-cont~ining compositions are from a heat exchange ~ystem of ~n internal combustion engine which typically contains between about 5 weight percent and about 95 weight percent ethylene glycol, and contains at least one metal, typicaily a heavy ~etal, and/or an oil component to be removed.
The instant process generally comprises 6teps of:
(i) adju~ting the pH of 6aid polyhydric alcohol-containing composition to between about 4.0 and about 7.5 by addition of an effective amount of an pH adjusting agent to form a pH-adjusted composition:
and (ii) adding an effective amount of a precipitating agent for at least one metal, preferably at least one heavy metal, and/or oil component present in the pH-adjusted composition; and (iii) preferably alsG includes adding to the pH-adjusted composition of step (ii) an effective amount of a coaqulating agent and an effective amount of a flocculating agent effective in forming a precipitate containing at least one ~etal: and (iv) passing the p~-adjusted composition through a first filtration means to remove a major amount of said metal-containing precipitate and, optionally, phy6ical skimming of the 6urface of said pH-adjusted composition to remove precipitate at said surface.

In addition to the above steps the instant treatment process may also include on~ or more of the following step~:
(v) passing the pH-adjusted composition from the first filtration means through a second 2 ~ 3 ~

filtrAtion means effective in the phy6~cal separation oP particle~ of a ~maller ~ize that oenid ~irst filtr~tion mean~;
(vi) passing t~e pH-~dju~ted compo6ition a~ter the s~cond filtr~t~on ~e~n~ through an organic ~eparation ~eans ~ffective in removing organi~ compound6 (other than the polyhydric alcohol(~)) from the pH-~d~usted composition;
(vii) passing 6aid pH-ad~usted composition through a ~hird filtrat~on means having an effective physical 6eparation of particlec by size ~maller than ~aid ~econd filtration means: ~nd (viii) passing ~aid pH-adjusted composition after filtration through an ion exchanger anion and/or cation ef~ective in the removal of at least one 601ubilized metal, preferably heavy ~etal, from ~aid pH-adjusted compo~ition.

DETAILED DESCRIPTION OF THE INVENTION
At ~he out6et it i~ important to note that although the instant invention i~ primarily directed to the treatment of ~pent antifreez * coolant ~rom the heat exchange systems (commonly referred to as ~cooling sy6tems~) of internal combu6tion engines, the process of the instant invention i6 useful in purifying a wide range of contaminated aqueous ethylene glycol compo6ition.
The term "haat exchange syste~n i employed herein to incl~de ~ny heat exchange system and includes cooling sy tems for internal co~bu~tion engine6, as commonly employed in ~utomobile~, trucks, ~otorcycles, airplanes, trains, tractors, generators, compressor~
and the like. The cooling ~ystem in automobiles ~nd h truckE nre representative of such heat exchange ~ystems for internal ¢ombustion engines. Automotive heat exchange ~y~tems and their con~truction are well known in the art ~nd are known to contain ~everal metals, including aluminum and lead ~older which with time may be dis601ved into the working antifreeze/coolant composition within the cooling ~ystem by phy~ical abrasion and/or chemical action.
The term ~6pent antifreeze/coolant" ~erein refers to an antifreeze/coolant which ~as operated as the antifreeze and/or coolant for a time in a heat exchange system, including an automotive cooling system.
The term "metals" as used herein in reference to the metal components present in the spent anti~reeze/
coolant includes metals such as aluminum and magnesium and "heavy metals" such as lead, iron, zinc, manganese, copper and molybdenum. Although aluminum i~ not a "heavy" metal as that term i6 understood in the prior art, the term "heavy metal~ as used herein is intended to include aluminum as to the metal components present in a 6pent antifreeze/coolant which are ~ubject to removal by the lnstant process. Owing to the construction of a cooling ~ystem 60 as to include aluminum surfaces in contact with a worXing antifreeze/coolant, it i6 common for the ~pent antifreeze/coolant to contain aluminum.
The antifreeze/coolant employed in heat exchange systems i8 generally a mixture of an alcohol (including methanol, ethanol, propanol, butanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, butene glycol, the monoacetate of propylene glycol, the monoethylether of glycol, the dimethyl ether of glycerol, alkoxy alkanols and mixture thereof); with the preferred alcohol~ being selected from the group consisting of ~,~;3 ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol and ~ixtures thereof, and preferably con~iQts of ethylene glycol, water and additional chemical component6 which provide corro ion protection or oth~r be~eficial function for the particular heat exchange 6y8tem(s) wherein it is employed. Further, it is well known that up to about 10% diethylene glycol or higher may be present in the grade of ethylene glycol employed to manufa~'ure antifreeze/ coolants for cooling systems.
Owing to the wide ~pread use antifreeze/coolants in internal combustion engine cooling systems based upon ethylene glycol/water mixtures, the instant invention is particularly useful in conjunction with ethylene glycol-based antifreeze/coolants heretofore employed as heat exchange fluids for the cooling sy6tems of internal co~bustion engines. Such ethylene glycol-based antifreeze/coolant6 representative of 6uch antifreeze/coolant compositions are those containing silicone/~ilicate additives and/or various carboxylic acids as corrosion inhibitors for the automotive cooling ~ystems. Other optional additives are typically employed in commercial antifreeze/
coolants in minor amounts of less than 50 wt. percent based on the weight of the antifreeze/coolant.
Typical optional additives included in antifreeze/coolantc include, for example, known corrosion inhibitors for aluminum or other metal~ in admixture with the oils and the hydrophobizing agents of the present invention such as, for example, molybdates, ~ono and/or di-aliphatic acids, e.g., sebacates, carbon~tes, silicates, alkali metal nitrates, alkali metal nitrite~, diisopropylamine nitrite, dicyclohexylamine nitrate, tolyltriazole, mercaptobenzothiazole, benzotriazole, zinc compounds, calcium compounds, phosphates, benzoates, and the like, or mixture~ thereof. ~urther, one or ~ore of the known inhibitor6 for variou~ ~etal~ are in an ~nhibitory effective ~mount~, i.e., ~n amount ~ufficient to provide a ~ea~urable amount of corrosion inhibit~on with respect to the Detal ~.g., copper, ~teel, bra~s, ~luminum, cast ~ron, ~older, ~tc.) ~urface6 to be protscted aE compared to the corrosion protection provided by the antifreeze/cool~nt without the6e inhibitor6. Other optional additives that ~ay be pre~ent in commercial antifreeze/coolants include:
wetting ~gent6 ~nd ~urfactant6 ~uch a8, for example, known ionic and non-ionic ~urfactant6 ~uch as the poly(oxyalkylene) adducts of fat~y alcohol6; defoamer~
and/or lubricants such ns the well-known polysiloxanes and the polyoxyalkylene glycol~; wear inhibitors, ~uch a~ the zinc dithiophospha~e~ and the zinc thiocarbamates; lubric~nt~, Euch as ~ilicone pump lubricants; and other ingredients known in the art of antifreeze/coolants that do not adversely affect the antifreeze/coolant characteri~tics sought to be achieved by the end use of the antifreeze~coolant.
Representative zntifreeze/coolant composition6 based upon polyhydric a~cohols which may be treated according to the instant invention after use in ~ heat exchange 6y~tem, i.e., when c~llected after use (e.g., -n "6pent" ~ntifreeze/coolant from an automotive cooling 8y5tem) include, but ~re not limited to, tho~e de6cribed in U.S. Patent Nos. 4,664,833, 4,287,077, 4,725,405, 4,704,~20, 4,684,474, 4,685,475, 4,687,590, 4,701,277, 4,561,990, ~,578,205, 4,584,119, 4,587,028, 4,5~8,513, 4,592,853, 4,629,807, 4,647,3g2, 4,657,689, 4,759,864, ~,851,145, 4,810,406 and 4,345,712; the aforementioned patent~ incorporated herein by reference. In the aforesaid patent6 are di6closed combinations of chemical components effective in protecting the ~etal ~urf~ces of ~uch cooling systems, _ g ._ ~uch being generally referred to ~s an ~inhibitor p~ckage.~
The spent Antifreeze/cool~nt ~ixtures obtained by r~oval from heat exchange Eystem~ of internal combustion engines ~re generally ch~racterized a containing ethylene glycol or other polyhydric alcohol(s) and are typically a mixture containing between About 95 volume percent and ab~ut 5 volume percent ethylene glycol and/or other polyhydric alcohol, preferably between ~bout 30 ~olume percent and About 70 volume percent. The actual amount of ethylene glycol and/or other polyhydric alcohol present in the antifreeze/coolant will depend ~n several factors. For example, during the "change-over" of an antifreeze/coolant in the cooling 6ystem of an internal combustion engine the cooling ~y~tem will be emptied nnd the removed antifreeze/
coolant placed in a collection cont~iner. The cooling ~ys~em will typically then be flushed with water and/or water with a minor amount of a cleaning agent. Thi# ~ubstantially water ~olution will typic~lly be emptied into the ~ame holding container as the original 6pent antifreeze/ccolant and, thus, further decrease the ethylene glycol concentration in liquid ~ixture to be recycled. Further, the spent antifreeze/coolant i6 typically characterized as containing at least one heavy ~etal elected from the group consisting of lead, iron, zinc, ~anganese, copper, molybdenum, and aluminum and v~rious organic oil8 from the internal combustion engine or present as a result of contamination after removal of the antifreeze/coolant.
~ he antifreeze/coolant will also typically contain one or ~ore organic compounds other than the polyhydric ~lcohol ~8) component. Such organic compounds may be present a~ a result addition as a ~unctional additive to the original antifreeze/coolant sr may be present a~ a degradation product of the polyhydr~c ~lcohol, e.g., ~thylene glycol, or other ~J ~ r~ ~

organic compound pre~en~ in ~he original ~nti~reeze/ cool~nt.
For example, it is well known that under the work~ng ~onditions that an antifreezeJcoolant ~xperiences in an automotive cooling sy~tem that therm~l degr~dation of ethylene glycol ~nd other organic compound~ pre~ent in the working antifreeze/ co~l~nt will re~ult i~ the pr~sence of org~nic degradation product6. Iypical organic degradation product~ of ethylene glycol include, but are not li~ited to, formic acid, glycolic acid and acetic acid. Antifreeze/coolnnts ~l~o are known to contain inorganic co~ponent~ a~ corro6ion inhibitors including, but not limited to, silicate, nitrate, nitrite, ~ilicone compounds, phosphate, chloride, ~ulfate, carbon~te nnd mixtures thereof, And ~alts commonly found in water.
Analy~es of spent antifreeze/coolant6 t~ken from commercial antifreeze/coolant change-over (including flushing liguids, e.g., water), are ~et forth in Table A:
\ ~ " ~

compone~t2 ~o~ V~l~e3 Hinh V~luç3 ~verage Valuel, 3 pH 8.5 10.0 9~3 Wt. ~ EG 12.1 40.0 28.8 Wt. % DEG 0.5 3.5 1.37 Wt. % PG ND 2.02 0.96 Cl 1 31 18.5 Sulfate 22 169 100 B 67 258 164.4 Cu ~.0 15.9 6.1 Fe 7.6 583 82.5 Al 1.8 71.3 13.7 Pb 1.5 136 25.6 Ca 1.5 34.1 9.13 Mg 0.9 19.9 5.9 Mo 3.6 56.8 17.8 Na 676 2074 1420 Si 40.8 269.1 126 ~ 8 Sn 0.9 24.7 11.8 Zn 1.1 27.6 5.~
TTZ 130 370 242.7 Acetate 12 219 48.9 Glycolate 121 858 503 Formate 2 241 129 Benzoate 10 2590 385 Oi~ ND 1.0 0.03 1 Lo~ h and Aver~ae Value~ Sin ppm e~cept ~here ~ho~n as vt X) nre ba~ed upon thSrty t30) 55 gallon ~ntifree~e/coolant ~plec t~ken fro~ collcc~ion tan~L ~t co~merci~l ontifreeee/cool~nt bu~ine~ser in the United Statefi of ~-leri c- .
2 Abbreviotionr have the fo!lo~ing ~e~nin~ XEG~ei~ht Percent Ethylene Clycol;DEG~Diethylene Glycol; PG~Prowlone Glycol; ~2 ~Strite; ~03 ~itr-te;
Cl-Chloride; F-Fluoride; P~Phorphoru~ Eoron; Cu-Copper; Fe-lron;
~l~Alu inu ; Pb~Lead; TTZ-Tolyltri-~ole; EDTA Ethylene Dla~ine Tetr-cetlc Acid;
nd Oil~ei9ht percenS o~l 8 nn inroluble orgonic phese; TSS-Totel Suspordod Eolid~ tppm; grnvinetric n31y~i~ uith 0 ~5 uicron filter); and hD-~elou detection li~it of 2 ppn Concentretionr re in p-rt~ per ~llion ~ppv) ~11 co~ponent~ ~re ~ivtn o-total of ~oluble nd in~olublo for~

~ 12 ~

~J ~ ~3 ~ (J

In one ~mbodi~ent the polybydric ~lcohol- containing co~po6itionE are t~ken ~rom a heat exchange ~y~te~, prefer~bly the cooling sy6teD of ~n internal combustion engine, and contain6 between about 5 weight perc~nt and ~bout 95 weight percent polyhydric nlcohol, pref~rably ethylene glycol, contai~ing at lea~t one heavy ~etal and typically containing an oil aomponent. The in~tant process generally comprises the stepB of:
(i) ad~u6ting the pH of ~aid polyhydric alcohol-containing compv6it$0n to between about 4.0 and about 7~5 by addition of an effective amount of an pH adjustin~ agent to form a pH-adju~ted composition; and (ii) adding ~n effective amount of a precipitating agent for at least one heavy ~etal and/or oil component present in the pH-adjusted composition.
In addition to the ~bove ~teps the instant treatment process al~o may include one or more of the ~ollowinq 6teps:
(iii) preferably algo includes adding to the pH-adjusted composition of 6tep (ii) kn effective amount of ~ coagulating agent ~nd an effective amount of a floccul~ting agent - effective in forming a precipitate containing ~t least one heavy ~etal;
tiV) passing the pH-adjusted composition through a fir~t ~iltration means to rsmove a ~ajor amount of ~aid heavy ~etal-containing precipit~te;
(v) pa6eing the p~-~djusted ~omposition after the fir~t filtration means through ~n organic 6eparation ~eans effective in removing organi~ compound~ (other than the polyhydric alcohol(~)) fro~ the pH-adjusted compo~ition;
- ~3 -~3 (vi) pa~6ing the pH-adjusted composition ~rom t~e fir~t filtration ~eans through a ~econd filtration ~ean~ effective in the physic~l ~ep~ration of particle~ of ~ ~maller aize t~at ~aid fir~t filtration ~ean~;
(vii) pa~sing said p~-ad~u~t~d compo~ition through a third ~iltrAtion nean~ having ~n effective phy~ical ~eparation of particles by ~ize ~m~ller than ~aid ~econd ~iltration means: and (viii) passing said pH-ad~usted composition after filtration through an ion excbanger (anion and/or cation) effective in the removal of at lea6t one ~olubilized heavy metal from said pH-~d~u~ted compo8 ition.

Prior to addition ~f the precipitAting agent the pH of the ~pent ~nti~reeze/coolant is adjusted by addition of an e~fective pH-adjusting agent to adjust the effective pH to improve the precipitation of heavy ~etal(~) and i6 preferably adjusted to a pH between ~bout 4.0 and about 7.5 and more preferably between about 4.5 and 7.O. This pH adju6tment improve6 ~he precipitation of heavy metal6 present in the 6pant antifreeze/coolant while concurrently adjusting`the p~
~t a ~ufficiently high pH ~o A5 to minimize acidic ~olubilization of heavy ~etal compounds. The pH-adjusting agent ~ay be any organic or ~norganic ~o~pouna which effectively ~d~usts the pH to the ~elec~ed pH, although it ~a~ been unexpectedly found that the u~e of nitric acid a~ the pH-ad~u~ting agent ~n con~unct~on with the u~e of aluminu~ nitr~te as the precipitating agent provides unexpected result~ for precipitating both ~olubili~ed and insoluble lead ~pecies ~nd for removing o~l component6 pre~ent in ~pent antifreeze/coolant from the cooling 6ystems of internal combustion eng$nes~ Organic hcid~, acidic organi~ salts, inorganic acids and acidic inorganic ~alts ~re employ~ble herein being effective in ad~usting the p~ o~ the antifreeze/coolant.
Representative acids include nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid, carboxylic acids, mixtures thereof nnd the like. It has been observed that ~alt~ u~eful aa both pH-adjusting agents and/or precipitating ~gents include the following representative acidic 6al~s: the chlorides and nitrate 6alts of calcium, magnesium, zinc, nluminum nnd iron;
the 6ulfate salts of magnesium, ~inc, aluminum and iron; ~nd the like. It is beneficial to employ nitric acid as the pH-adju~ting agent ~o as to prevent the introduction of corrosive anions and/or anions which may interfere with precipitation of heavy metals present in the spent antifreezefcoolant during the pH
adjustment ~tep, although the csncurrent adjustment of pH and precipitation of heavy metal(~) with an acidic ealt, e.g., preferably an aluminum nitrate hydrate ~uc~ as ~l(NO3)3.9H2O, i~ within the scope of the instant invention.
~ he precipitating agent may be selected to provide for the formation of heavy ~et~l(s) precipitate in the pH-adjusted antifreeze/coolant. The precipitating agent need not result in the actual formation of a fiolid precipitate if a coagulant and/or flocculant are to be employed but only need render heavy metal(s) and/or oil pre ent in the ~pent antifreeze/coolant ~usceptible to precipitation in the presence of coagulant and 1Occulant. When the precipitating agent i6 employed without the use of a coagulant ~nd/or flocculant, it has been observed that the rate o~ formation and ~eparation of the precipitate may be too 810w for effective commercial use of the process, although the benefits of instant process will ~ 3 no~etheless be ~chievedO The precipitatinq ~gent is added in an effective amount to precipitate ~ selected amount of heavy metal(~) present in the spent antifreeze/coolant. A~ aforementioned, the heavy ~etals most commonly found in 6pent antifreez2/coolant are lead (Pb from lead solder corrosion), iron (Fe from water and radiator corrosion), zinc (Zn from metal corrosion and ~rom zinc ~alts employed in antifreeze/coolants), copper (from radiator corrosion) and aluminum from corrosion (water pump, radiator, engine head and engine block). It has been observed that the concentrations of solubilized lead and iron in a 6pent antifreeze/coolant are on the order of up to about 100 parts per million (ppm) lead, and up to ~bout 25 ppm iron, respectively. It has also been observed that insoluble lead components may be present in concentrations up to about 150 ppm and insoluble iron components may be present in concentrations up to about 600 ppm. Typically total concentrations of lead and iron ~re set forth in Table A, hereinbefore. ~he effective amount of precipitating agent for such concentrations of Pb and Fe will typically be between about 100 ppm and about 6000 ppm (based upon u~e of Al(N03)3.9H20 a6 the precipitating agent) and preferably between about 590 ppm and about 5000 ppm.
The effective amount of precipitating agent employed is related to the equivalents of heavy metal(~) to be precipitated and will vary depending upon the equivalents of the selected precipitating agents u6eful herein for forming heavy metal precipitates.
As aforementioned, selection o~ the precipitating agent may be from that group of organic and/or ~norganic compounds effective in the foYmation of a substantially insoluble species of at least one heavy metal present in the ~pent antifreeze/coolant at the adjusted pH and may include ~alts of heavy metal(s) ~uch as phosphates, chlorides, ~ulfates, oxalates and J~
the like. The ter~ ~ub~t~ntially insoluble~ ifi ~e3nt to refer to a heavy ~etal ~p~cies which will form a~
one or more pr~cipitable specie~ ~t a pH between about pH 4.0 and pH 7.5. Surpri~ingly, it ha~ been found that u~e of alu~inum nitrate (Al(N03)3.9H20) a~
A precipitating agent for lQad sfter pH adju6t~ent (to between ~bout 4.0 and about 7.5) of the antifreeze/coolant with nitr~c acld (A8 the pH-adjusting agent) i6 p~rtiGularly advant~geou6 for use in formation of a lead precipitate and i6 al60 ~ost beneficial for use in forming a precipitation with the additional use of a coagulant and/or flocculant. The exact mechanism by which aluminum nitrate benefici311y provides for formation of ~
precipitate o~ lead is not fully understood but may relate to che~ical reaction wi~h lead and/or ~ay involve physical adscrption o~ lead Epecies on the 6urface of aluminum, hydroxide or an nluminum oxide or other aluminum ~pecies formed n 6itu by addition of alu~inum ~itrate.
The ~election of the coagulant and flocculant i~
correlated to the alcohol-based antifreeze/coolant ~eing treated and i~ made to provide for effective precipitation and filtration of t~e precipitate ~nd separation of the precipitate by a mechanical filter. --The coagulant may be any of the well known commercially available coagulant~ including Calgon 2466, Cyanamid 572C, ~lxtures thereof and the like.
The flocculant ~ay be any of the well known co D erci~lly available flocculants including PRIMAFL~C~ C-3, MAGNIFL~C 572C, Calgon 7736, Cyanamid 1820A, mlxtures thereof and the like. Calgon FOL-~-Z~ 24~6 is a high ~olecular weight, high c~arge cationic polyelectrolyte available from Calgon Corporation. PRIMAFL~C C-3 ~ a cationic polyelectrolyte flocculant characterized as water-~oluble poly~ina (29-31%) ~nd i~ ava~lable from Roh~ and Haas Co~p~ny. Calgon POL-E-Z 7736 i8 ~igh ~olecul~r weight, anionic polyelectrolyte available from Calgon Corporation. MAGNIF~C~ 572C
~floccul~nt) i~ a very low ~olecular weight, liquid cationic flocculant available fro~ American Cyanamid C~mpany. Cyannmid 1820A is a c~tionic flocc~lAnt available ~rom Amer~can Cyan~mid Company. ~he Relection of coagulant~ and floccul~nts for precipit~ting ~olid~ ~n water ba~ed sy6tems i~ well known A~ evidenced by the di6cussion in ~he Nalco Water Handbookn, Second ~dition, (ISBM 0-07-045872-3), 1988, at Part 2, Chapter 8 ~t pages 8.3 to 8.23, incorporated herein by reference.
In one e~bodiment the antifreeze/coolnnt i8 n spent antifreeze/coolant from the cooling syfitem of ~n internal co~bu~tion engine, typically from an automobile or truck, having its pH adjusted to between about 4.5 and about 7.0 with nitric acid a~ the pH-adju6ting agent, followed by treatment with an effective amount of aluminum nitrate as the precipitating agent, followed by addition of coagulant, preferably Calgon 2466, and flocculant, preferably Calgon 7736. The effective amount of coagulant i8 typically between about 75 ppm and about 300 ppm, preferably between about 150 ppm and about 225 ppm. The effective a~unt ~f flocculant is typically between about 25 pp~ and about 300 ppm ~nd preferably between about 50 pp~ and about 100 ppm. It has been observed that there ~s an effective concentration range of coagulant and flocculant in the coagulant and flocculant ~olutions when such are to be added to the anti~reeze coolant after such ha~ been treated with the pH-adjus~ing agent and the precipitating agent. Surpri~ingly, it ha~ been found that commercially ~vailable cGagulant~ and flocculant6 are ~old at concentrations ~ignificantly greater than benefic~ally ~u~table or u~e in the in~t~nt proc~s.
For example, when treat~ent of ~ lead-containing nutomotive antifreeze/cool~nt ~s effected with Calgon 2466 a~ the coagulant ~nd Calgon 7736 a~ the flocculant after t~e antifr~eze/coolant ha~ been tr~ated w$t~ effective ~ountc of nitric acid and aluminum nitrate, it has been observed that the coagulant and flocculant as commercially av~ilable should be benefici~lly dilutad from its original commerci~l concentrntion by the addition of water or other ~uitable ~olvent. For example, suitable dilution of coagulant Calgon 2466 and flocculant Calgon 7736 for use in the in~tant invention ~y be prepared by mixing 100 partG (by weight or by volume) of the coagulant or the flocculant with water to for~
up to 40,000 part6 of coagulznt or ~locculant 601ution or use in the instant invention. The aforementioned water diluted ~ixtures will preferably result in ~ffective concentrations of coagulant or flocculant in the resulting dilu~ed water mixtures wherein the concentration of coagulant or flocculant i8 O- 2S% to 5.0~ of the concentration of the original com~erci~l concentration of the coagulant or flocculant.
Although the exact reason for the beneficial effect obt~ined by u6e of a diluted coagulant or flocculant ~nd the beneficial correlation of the concentration of the coagulant and flocculant to the ~ntifreeze/coolant i~ not fully under~tood it has been observed that such ~ay be related to the unique chemical environment re6ulting from the use of an originally formulated ethylene-glycol based antifreeze/coolant in the cooling ~y6tem of ~n internal combustion engine and from localized concentration6 of coagulant or flocculant resulting from the inherent difficulty in ~ixing large ~olumes of liguid~. The ~ctual ~J ~

correl~tion in the conc~ntration i6 believed to re6ult in an effe~tive concentration of coagulant and floccul~nt, ~s de cribed nbove b~6ed upon the range of the heavy metal6 ob~erved to be pre~ent in antireeze/cool~nt removed ~rom auto~otive cooling ~yste~s.
The anti~reeze/coolhnt ~ill ~orm ~ ~olids phase (precipitate~ ~nd a liquid phase after treatment with the pH-adjusting agent and precipitat$ng agent and in a further embodiment preferably treatment ~s to coagulant and fl~cculant, as described above. The precipitate may be removed by mechanical filtrstion.
In addition, it ha6 been observed that proper agitation o~ the treated antifreeze/coolant enables ~kimming of precipitate fro~ the top of the treated antifreeze/coolant as some portion of the precipitate i6 present ~t the surface of the treated antifreeze/coolant. Further, it hac been observed that recirculation of the spent antifreeze/coolant in the mixing tank by introduction of the recirculated stream above the 6urface of the antifreeze/coolant in the mixing tank is beneficial in forming a precipitate suitable for ~kimming a~ compared to the form of the precipitate formed when the recirculated ~tream i~
~ntroduced below the ~urface of the antifreeze/coolant in the ~ixing tank. Accordingly, it i6 preferred to ~ave a recirculation of the spent antifreeze/coolant in the mixing tank from below the surface of the antifreeze/cool~nt in mixing tank to a position ~ufficiently above the 6urface so a~ to expose the recirculated antifreeze/coolant to air whereby so~e degree of contact with ~ir occurs, such having been observed as effective in i~proving the form of ~he precipitate for 6kimming. This preferred recirculatio~ is preferably commenced prior to the additio~ of the pH adjusting agent and precipitating ~ J,~

gent. It has been observed that the use of a process step wherein skimming of the ~urface of the treated antifreeze~coolant i6 employed i8 beneficial in reducinq the amount of precipitate which must be removed by filtration. This reduction in the amount of precipitate to be removed by filtration both increases the rate at which the treat~ent process ~ay be carried out and increases the useful l~fe of the filtration means, thus decrea~ing the nu~ber of times the filtration means must be replaced. The effective particle size removed by the filtration means will depend in part on whether a single or multiple filtration steps are to be employed. If a single filtration step is to be employed the filtering means will preferably remove particles having a particle eize greater than about 50 microns, although use of a 6ingle filtration step i6 not employed. If this first filtration is the first filtration means in a eries of filtration means, then this first filtration means will preferably be effective in the removal of particles having a particle ~ize greater than about 100 microns. In one embodiment it has been found to be beneficial to employ at least three filtration steps wherein the first filtration means is effective in removing species larger than about lQ0 microns, a ~econd filtration means effective in removing species larger than about 40 microns and a third $iltration ~eans i8 beneficially employed where~n ~uch i8 effective in removing 6pecies larger than about 5 microns. An optimal fourth filter may be employed wherein ~uch fourth filtration means is effective in removing species larger than about .2 microns, preferably larger than about .1 microns. ~echanical filtration means having effective filtration 6ize8 as above di~cussed are well known in the prior art.
Optionally, as herein described, an organic separation ~, filter ~ay be pr~vided in conjunction with the previously discussed ~echanical filters.
In A further embodiment, the treated, filtered, spent antifreeze/coolant i6 pa6sed through an active filter for the removal of organic compounds, e.g., oils, aldehydes and organic acids. Representative of such active filter6 are the various ~ctivated carbon filters sold under the tradename Fulflo~ by Parker Hannifin Corporation-Commercial Filters Group or a No.
2 Anthacite filter sold by Penfield Liguid Treatment.
The Fulflo~ filter i8 characterized by it~ honeyco~b filter 6tructure having an activated carbon surface while the Penfield filter is a loosely packed carbon filter. The active carbon filter acts as an organic 6eparation means effective in the selective removal of organic compounds from the polyhydric alcohol/water mixture forming spent antifreeze/coolant.
It has been found beneficial to provide two or more filtration means for the spent antifreeze/coolant (either before or a~ter aforementioned organic ~eparation means) to effectively remove materials greater than about 5 microns, and more preferably t~
remove materials greater than about 0.2 microns. It has been found that the use of one or more additional mechanical filtration ~teps in conjunction with ~
fir~t filtration means step is most advantageous in the separat~on of bulky organic and inorganic compounds and both large and 6mall particulate solids. Further, by providing ~ series of ever ~maller size filters the likelihood of clogging ~maller pore filter6 with larger materials is effectively eliminated. In one embodiment the process employs a first filtration means effective in removing ~aterials greater than bout 100 microns, a second filtration means effective in removing ~aterials greater than about 40 microns, a third filtration I~J ~ ~ .rJ L 1I J~J

Dean6 effective in re~oving material~ greater than about 5 microns, and a ~ourth filtration means ~ffective in removing ~aterial6 greater than about 0.2 microns.
In ~ further embodiment the in~tant proce~s ~ay ~lso involve treatment with at least one ion-exchange resin to remove solubilized ~pecies present in ~he spent ~ntifreeze/coolant. A possible result of the initial pH-adjustment of the instant process is the formation of solubilized cationic and/or anionic species of one or ~ore heavy metals. The pH-adjustment to a pH between about 4.0 and about 7.S
is selected 80 to minimize the formation of 6uch solubilized cationic and/or anionic species of such heavy metals, especially solubilized lead ~pecie6.
Although it has been observed that no 6uch solubilized cationic ~pecies (less than the lowest measurement limit of 2 ppm), e.g., 601ubilized lead, are present after the addition of the pH-adjustment agent, precipitating agent, coagu~ant and flocculant it is believed to be beneficial to treat the filtered, spent antifreeze~coolant with a cation ~nd/or anion exchange re~in to assure that essentially no 601ubilized heavy metal is present. It has also been observed that such ion exchangers also may act as filtration means for effectively removing materials having a size greater than about 2.0 microns. Further, since some solubilized species will pa~s through filtration means having a pore ~ize greater than 0.005 and remain as solubilized ~pecies it is beneficial to employ an ion exchange materi~l whereby such species are selectively removed by other than physical ~eparation.
It is desirable to remove any ~olubilized heavy metals ~rom the ~pent antifreeze/coolant o that ~uch ~ay be properly handled and properly di6posed.
Accordingly, the filtered, spent antifreeze/coolant i3,i~ L~

may be treated with a cation exchange and/or ~nion exchange resin effective in the removal of solubilized heavy metal cation(s), or ~nions. Cation exchange resins u~eful in the re~oval o~ solubilized heavy metal cations include well known cation exchange resin~ such as Rohm and Haas DP-l, Rohm and Haas Amberlite~ IRC-718, Duolite~ C-464, Purolite C-106 and Ionice CNN. Rohm and Haas Amberlite IRC 718 is preferred owing to it8 effectiveness in the removal of solubilized lead and its cost.
Amberlite~ IRC 718 i8 a chelating cation exchange resin having a high affin~ty for heavy metal cation6 over alkali or alkaline earth metals in the pH range between about 4.0 and about 7.5 and is formed from Dow Chemical Company's SBR resin; a styrene-divinyl benzene material and is available from Rohm and Haas. Anion exchange resins which may be employed herein include Rohm and Hass Amberlite IRA 400;
Purolite A-600; ronic~ ASB-l; and Duolite A-109.
It has been observed that the use of an anion exchange resin may not always be beneficial owing to the high concentration of anions present, present in the treated antifreeze/coolant, e.g., nitrate, in the treated antifreeze. Nevertheless, there may be instances where an anion exchange resin may be beneficially employed, e.g., where the anion exchange resin is ~elective to one or more anionic specie~.
Further, it is well known that ion exchange resin~
having both cation and anion exchange characteristics are commercially available and such dual exchange resins ~ay be employed herein. For example the non-exchange media of U.S. Patent No. 4,908,137, incorporated herein, is believed to be a novel non-exchange media useful herein in the removal of heavy metal ~ons.
The treatment with the cation and/or anion D-lS600 exchange resin (nion exchange"~ may be acco~plished after ~uitable mechanical filtration of the ~pent antifreeze/coolant after the ~ddition of the pH-adjusting agent, precipitatinq agent, coagulant and flocculant ha6 resulted in precipitation of in~oluble heavy ~etal compound6. Since the pr~ence of large particulate matter will tend to clog most ion exchange material6, it i8 preferred that the ion exchange step follow a mechanical filtration step where particles having a size greater than about 5 ~icrons have been removed.
The reference to ~filtration means" is meant to designate the various filtration devices hereto known in the prior art for use in the physical separation of materials (including both organic 6pecies and inorganic species) based on ~lze. Filtration devices suitable for use in the instant invention are co~mercially available. For example, the first filtration means of 100 microns and above may be a 3M
Brand liquid filter bag formed from polypropylene or stainless ~teel as described in 3M sales brochure 70-0701-3209-0(201)iii 1989, incorporated herein. The second filtration means having separation means of about 40 microns and above may be a 3M Brand liquid cartridge filter having a pleated polypropylene design as described in 3M sales brochure 70-0702-2790-8(201.5)11, incorporated herein.
In one e~bodiment the treatment with a cation exchange re~in may be replaced in part or in whole with treatment with ~n anion exchange resin. In 60me instances the heavy ~etalts) may be present or may be converted into an anionic species. In some instances it may be beneficial to treat the spent antifreeze/coolant to form an anionic ~pecies of the heavy metal, ~ince in some instances its removal a~ an anionic species may be more effective than its removal ~ ~ P3 ~ r' a~ a cationic species. The formation of such anionic ~pecies may be beneficial owing to the desire to increase the reserve alkalinity of the ~pent antifreeze/coolant in preparation for itB reproces~ing into a working antifreeze/coolant for u6e in an automotive cooling sy~temO
The final composition obtained from the various e~bodiments of the instant invention are characterized as having lower concentrations of one or more heavy metal components and i5 typically characterized as being an aqueous composition(s) containing between about S and about 95 weight percent polyhydric alcohol, preferably ethylene glycol, and containing le6s than ~bout 5 ppm soluble lead, generally les~
than 2 ppm soluble lead. These aqueous polyhydric alcohol compositions ~ay be employed in the manufacture of a working antifreeze by addition of corrosion inhibitors hereto employed in the manufacture of antifreeze/ coolant compositions or may be employed for other common uses for the polyhydric ~lcohol.
When the use is for antifreeze/coolant, ~uch corrosion inhibitors will be employed in effective amounts correlated to any residual concentration of cGmponents of corrosion inhibitors present from that present in the spent antifreeze/coolant which wa~ not removed by the instant process. For example, ~olubilized ~ilica and nitrate may be present in the compositions derived from the instant proce~s, since t~e various ~teps of precipitation, organics ~eparation and ~echanical filtration may not be effective in their complete removal. Chemical analysis of the treated 6pent antifreeze/coolant will provide a ba~ for correlating the e~fective amount of corrosion inhibitor which should be added to the treated aqueous antifreeze/coolant to form an effective working antifreeze. In some instances the formation of a working antifreeze may also require the ~ddition of ethylene glycol or fresh antifreeze or removal of water to obtain a solution having the de~ired freezing point. Removal of water from the aqueous ethylene glycol may be by distillation, extraction or other known ~eparation ~eans.
The v~rious steps of the instant process ~ay be carried out at an effective temperature wherein the antifreeze/coolant is in a liguid 6tate and i6 preferably between about 18-C to about 45-C and at an effective pressure, preferably between about 0.9 atm to about 1.1 atm, or such ~ther temperatures or pressures as may improve the process.
It ha~ been observed that it is not preferred to pass the precipitate formed by addition of the pH-adjusting agent, precipitating agent, coayulant and flocculant through a high shear mechanical pump, since a high shear mechanical pump tends to form particle~
of smaller ~ize by mechanical shearing, thus making it more difficult to remove particles with large size filters. Accordingly, it has been found that it i6 preferred to place a pumping means after the first filtration ~tep which to provide a pulling a~tion after the first filtration means or alternatively, provide a diaphragm or other low shearing type pump ahead of first filtration means. Representative of ~gh ~hear pumps is a ~OYNO~ SP Pump (available from Robbins & Wyers, Inc.) and representative of a low ~hear pump ic a Twin Diaphragm Pump (available from the ARO Corporation). It has also been observed that by employing ski~ming of precipitate from the surface of antifreeze/coolant in the vessel to which the pH-adjusting agent, precipitating agent, flocculant and coagulant are added that sufficient precipitate can be removed to significantly reduce the problems ~I~J~ jx sssociated with hish ~hear pumps.
The instant process may be carried out in a batch ~ise or, alternatively, in a continuous mode. When c~rried out in a batch ~ode, the process i~ conducted by placing a selected guantity of 6pent antifreeze/cool~nt in a vessel. The pH-adju~ting Agent and precipitating agent are added followed by addition of the coagulant and flocculant whereby a precipitate will be formed. The content6 of the ve6sel are then filtered by a first filtration means to remove the precipit~te from the liquid phase. It has been found advantageous to minimize the mechanical action on the precipitate during thi6 fir~t filtration step 60 as to minimize the fraction of smaller size particles which form as a result of mechanical abrasion. Such mechanical abrasion may be minimized by manual mixing for about 5 minute6 after all inqredients have been added during which time it may be advantageous to skim precipitate from the surface of the mixture. ~he p~-adjusted composition may then he ~equentially passed through one or more filtration means, organic separation means, additional filtration mean~ and ion exchange ~eans.
The treated antifreeze/coolant may be suitable for use as a component of a working anti-freeze/coolant without further treatment or may be distilled to remove water and/or organic component and, thus, provide a higher content polyhydric alcohol solution.
Alternately, the instant process is well suited to be carried out in ~ continuous manner based upon the process steps employed in the batchwise process discussed above.
The instant proces~ may also be employed ~s ~
treatment ~tep in an antifreeze/coolant change-over process where the treated antifreeze/coolant i~
returned to the cooling system of an internal combustion engine after the addition of inhibitors ~nd other ~uitable chemical~. Process~6 wherein a treated antifreeze/coolant is reintroduced to ~n engine cooling sy6tem include U.S. Patent Nos. 4,149,574, Re. 31,274, 4,791,890 ~nd 4,792,403; said patents incorporated herein by reference. For example, in U.S. P~tent No. 4,793,403 the instant process may be substituted for the ~econd means ~or treating the removed coolant (see: column 3, line 11 to column 3, line 28). In one embodiment the instant process is employed as the intermediate treatment step in the process of copending U.S. Serial No. 200,347, filed May 31, 1988, entitled, "FLUSH AND FILL METHOD AND
APPARATUS", incorporated herein by reference thereto.
In such a process a first liquid (spent antifreeze/
coolant~ is removed from a cooling system through the radiator neck opening via an elongatea hollow tube, treated according to the instant process and then reintroduced after treatment as the antifreeze/coolant (second liquid) into the cooling 6ystem via the radiator neck via an elongated hollow tube (the same or a second hollow tube). The treatment step i6 according to the instant invention and includes addition of appropriate chemicals to form a working antifreeze/coolant. The process of U.S. Serial No.
200,347 eliminates the need to acces~ the cooling ~ystem at more than one location and eliminates the need to cut hos~s ~or acces~ to the cooling system.
In general, a process according to the instant invention used in conjunction with a process according to U.S. Serial No. 200,347 comprise~ flushing/filling an automotive cooling ~ystem containing an antifreeze/coolant first liquid using a ~lushing apparatus comprising in combination a pumping ~eans, liquid switchinq means, an elongated hollow tubular member and an automobile having an automobile radiator havinq ~ neck openlng ~nd an over-flow container, ~aid neck opening and ~aid over-flow container containing an antifreeze/coolant fir~t liquid, to be replaced with an antifreeze/coolant ~econd liquid (compri~ing the antifreeze/coolant first liquid treated according to the instant invention and then provided with an ~nhibitor package), wherein ~aid elongated hollow tubular me~ber forms an elongated open fluid pas6ageway extending into the ~utomobile radi~tor through said neck opening for accessing said antifreeze/coolant fir~t liquid, one end of the elongated hollow tubular member adapted to engage a connecting means in a fluid tight relation hip to connect the said elongated tubular ~ember to said pump means and switching means and for removing said first liquid and for introduc~ng said second liquid through 6aid elongated hollow tubular member to said automobile radiator, said process comprising:
a) removing at least a portion of the anti~reeze/coolant first liquid ~rom the automotive cooling system through said elongated hollow tubular ~ember using ~aid pumping means connected to said liquid ~witching means;
b) treating ~aid first liquid according to the instant invention and adding thereto an inhibitor package to form an antifreeze/coolant second liquid;
~nd c) introducing ~aid antifreeze/coolant second liquid to said automotive cooling system through said elongated hollow tubular member using said pumping means and switch;ng means.
The instant proce~s is beneficially carried out using a recycle apparatus comprising:
(i) holding ~eans for holding ~aid 6pent antifreeze~coolant;
(ii) pH adjusting means for adjusting the pH of ~3 ~ r .~ ~ ~3 $

~aid epent antifree~e~coolant with a pH
~djusting agen~; And (iii) addition ~eans ~or adding a precipitating agent to 6aiB ~pent antifreeze/coolant.

In ~ further embodiment the recycle apparatus comprises:
(1) holding means into which a spent antifreeze/coolant may be placed;
(ii) pH adjusting me~ns for ad~usting the pH of the spent antifreeze/coolant in said holding means;
~iii) addition means for introducing into said holding means at least one of a precipitating ayent, a coagulant ~nd a flocculant;
(iv) pumping means for removing the spent antifreeze/coolant from aid holding means;
(v) mechanical ~eparation means for removing solids from said ~pent antifreeze/coolant based upon the cize of said solids;
(vi) organic ~eparation means for removing one or more component6 of 6aid spent ~ntifreeze/coolant on the basis of chemical reaction, chemical adsorption or chemical absorption; and (vii) ion exchange means effective in the removal by ion exchange of at least one ~olubilized ~etal ~pecles in ~aid spent antifreeze/coolant.
In this embodiment the recycle apparatus typically ~ncludes at least items (i), (ii), (iii), ~iv) and (v) whereby the recycle apparatus is effective in re~oving the precipitated 601 ids in the holding mean~ after addition of the pH adjusting agent and precipitating agent. Further, the mechanical ~eparation means ~ay ~ ~3 actually be one or more filters effective in the remov~l of sol~d~ of various 8ize6, e.g., greater than 100 microns or 40 ~icrons or 5 microns.
The holding meanE may be a storage tank of conventional design with inlet and outlet ports for introduction of the original spe~t or recirculated antifreeze/coolant and the treated antifreeze/coolant, respectively. A mechanical mixin~ or stirring ~ean~
i8 typically employed to mix the contents of the holding means. The pH ad~usting means and addition means ~ay be any liguid or dry addition apparatus for introduction of the pH adjusting ~gent, precipitating agent, coagulant and/or flocculant. The pumping means may be any device effective in transferring the content6 of the holding means to another process step or to another storage area, including displacement by the force of gravity. The mechanical 6eparation means and organic fieparation means ~ay be one or more filters as described in the instant application with reference to the instant process. The cation exchange means may be one or more of the cation and anion exchange resins described herein.
In addition to the above recycle apparatus it has been observed that it may be beneficial to employ ~kimming means and recirculating means in combination with the holding means, pH adjusting means and addition ~eans. According to this embodiment the recycle apparatus compri~es:
(i) holding means into which a spent antifreeze/coolant may be placed;
(ii) recirculating means for circulating spent ~ntifreeze/coolant in said holding means from a point below the surface of said spent antifree~e/coolant to a point above the 6urface o~ said spent antifreeze/coolant, whereby the recirculated spent antifreezeJcoolant ~"e ~ r contacts a~bient air prior to its recirculation into said spent ~ntifreeze/coolant;
(iii) p~ adiusting ~eans for ~d~usting the pH of the spent ~ntifreeze/coolant in ~aid holding ~eans;
(iv) addition ~eans for introducing into said holding means at lea6t one of a precipitating agent, a coagulant and flocculant;
(v) ~kimming means for removing solids from the 6urface o~ ~aid spent antifreeze/coolant in said holding means: and (vi) may optionally contain one or more of mechanical ~eparation means, organic separation means and ion exchange ~ean~, as discussed above.

~XAMPLES

The ~ollowing examples are provided to further illustrate the invention and are not intended to be limiting thereof. As employed in the following example~ the following abbreviations ~hall have the following meanings:
Wt. %: Weight Percent EG: Ethylene Glycol DEG: Diethylene Glycol PG: Propylene Glycol TTZ: ~olyltriazole NO3: Nitrate S~4: Sulfate F: Fluoride Cl: Chloride EDTA: Ethylene Diamine Tetracetic Acid TSS: Total Suspended Sol~ds (ppm; gravimetric analysis with 0.45 ~icron filter) Oil: Wt. % Oil as hn insoluble organic phase.
Elements are referred to by their chemical symbols, e.g., Al is aluminum, Pb is lead, and etc.
~1: milliliter ND: None Detected at 2 ppm or higher.

~ ~ r~

A ~pent antifreeze/coolant was obtained from commercial anti~reeze~coolant change-over facilities and wa~ from the coolin~ ~ystem6 of automotive and truck engines. The spen~ ~ntifreeze/coolant was treated according to the instant invention u~ing the following squipment in the order listed:
(1) Mixing Tank;
~2) 1/2n Diaphra~m pump:
(3) 32~ Bag Filter (3M 527A~ 99.99 at 20 micron);
(4) 1211 Bag ~ilter (McMa6~er Carr 5167K56, 100 micron);
(5) 20" Cartridge Filter (Pall RF400, 40 micron);

(6) 101l Activated Carbon (Filter Fulflo RC10, 10 micron);

(7) 20" Filter (3M 323A, 2 micron); and (8) Cation Exchange Resin tRohm and Haas Amberlite IRC-718).

A 5125 gallon ~ample of the spent nntifreeze/cooling was placed in the mixing tank followed by the addition of 11.889 gallons of a 70 wt. percent nitric acid (remainder water). The contents of the mixing tank were then mixed by a mechanical mixer for 20 minutes. To this mixture was added 110.23 pounds of Al(N03)3-9H2O powder- This mixture was mixed for 60 minutes. To this mixture wa6 ~dded 200 gallons of 0.5 weight percent coagulant Calgon 2466 and ~6.7 gallons o~ 0.5 weight percent flocculant Calgon 7736. The resultin~ ~ixture was then mixed for e~ght hour6 and filtered using the above noted filter6 in the order li6ted.
Tables I and II 6how the analysis of the 6pent antifreeze/coolant both before and after treatment by the process of this invention. In Table I, the analysis of ethylene glycol, diethylene glycol and propylene glycol was conducted by 6tandard refractive index and gas o 34 _ S~ ~J 3' '~

chromotographic methods, the oil percent was conducted by a gas chromotography, the total suQpended solids were conducted by gravimetric analysis and all other ~n~lyse~
were conducted by ~igh Pressure Liquid Chromatography (nHPLCn) analysis or Ion Chromatography (nICn). Table II
shows the result6 of ICP analyses of ~everal metal6 ~n their 601uble ~nd insoluble forms both before treatment and after treatment according to the instant invention. In addition, the precipitate collected by the first 100 micron filter bag was analyzed. Table I and Table II demonstrate the effectiveness of the instant process in removing heavy metals, particularly lead, iron, copper, aluminum, magnesium, zinc and oil from spent antifreeze/coolant compositions. Referring to Table I, it i8 shown that in one embodiment of the instant process that after treatment the concentrations of TTZ, BZT, oil, benzoate, glycolate and total 6uspended ~olids ~nTSS"~ ha~e been reduced.
Referring to Table II, it is shown that after treatment the ~oluble forms of aluminum, boron, calcium, iron, potassium, magnesium, ~olybdenum, phosphorus, lead, silicon and zinc are reduced. The insoluble forms of aluminum, boron, iron, magnesium, ~olybdenum, phosphorus, lead and zinc were reduced.
It is particularly important to note that after treatment according to the invention that no ~oluble or insoluble lead was present in the antifreeze/coolant down to the detection limits of ICP analysis (about 2 ppm) and, accordingly, i~ consistent with current and presently propossed regulations of the Environmental Protection Agency as being a non-hazardous material. Further, it has been observed that the form of the heavy metal6 in the precipitate i~ such that the heavy metals are not leachable by water. Further, the precipitate contains various useful metal components and may be recycled for use as a component in cements, concrete, or used in other metal layered areas.

J ~

~rIFREEZ~COOL~NT CO~ITIQ~
BEFORE AND AFTER CHEMICAL ~ATME~
y~ 13efore ~reatment l~ter Treat~ent PH 8.3 6.39 EC;, Wt % 53 . 0 48 .1 Dl:G, Wt % 2 . 0 1. 9 PG, Wt ~6 0 . 33 3 . 34 TTZ, ppm 908 258 ~ZT, ppm 114 ND
N02, ppm 92 115 NO3, ppm 1029 4166 Benzoate 3520 2896 Oil, ~6 0.5 ND
F , ppm 180 1. 41 Cl, ppm 137 141 8O4, ppm 290 259 Acetate 55 66 Clycolate 820 660 ~ormate 199 197 llny ~cid, % 0. 05 0. 04 TSS, ppm 509 19 . 0 ~J ~ s ~

~A~1, 2 ANTIFR~SEZ~COOL~ COMPO~ITION

~LEME~T NAME ~QLUBLE FORN INSOLUBLE FORM PRECIPITATE
Before ~ter BefQre Af~
Al 2.6 ND 6.1 ND 1340 B 434.8 303.6 23.7 3.2 1493 Ca 14.7 ND 6.7 ND 100.1 Fe 2.4 ND 23.6 ND 32.6 X 1206 986.6 ND ND 789.5 Mg 8.1 ND 3.0 ND 30.6 ~o 48.5 20.5 ND ND ND
Na 2811 2308 65.0 30.9 2110 P 646.1 240.8 24.9 ND 95.8 Pb 3.0 ND 10.2 ND . 11.5 Si 66.5 31.4 5.3 ND 15200 Zn 5.6 ND 5.4 ND 5.0 -1 Concentr~tion in pert~ per ~ on ~ppJ);
2 ~D ~eon~ not detect-d t 2 pp~ or higher ~P To~icity T~ting ~xtr-ct~ble l--d~ r~ult~ wre 1~ th~n 0 1 ppr ~ PIIE 2 Treatment of a ~pent antifreeze/coolant ~btained from the cooling ~ystems of automotive and truck engines was treated according to the instant invention u~ing the following combination of equip~ent in the order listed:
(1) 30 gallon tank;
t2) 1/2" Diaphragm air pump;
(3) 12n 50 micron Bag Filter (McMastex Carr No. 5167K56);
(4) 20~ 40 micron Cartridge (Pall No. RF400);
(5) 10" 10 ~icron Carbon Filter (Fulflo No. RC10);
(6) 20n ~ 5 ~icron Cartridge Filter (Pall RF050); and (7) l.R liter Cation Exchange Resin (Rohm and ~aas Amberlite No. IRC-718) A 10 gallon ~ample of a ~pent antifreeze/coolant w~s placed in the 30 gallon ~ixing tank followed by the addition of 60 ml of 70 weiyht percent nitric ~cid (remainder water). To ~;~q thi6 mixture wa6 added 0.24 pounds of Al(N03)3.9H20 powder. Thi6 mixture wa8 mixed for 15 minute~. To this ~ixture was added 1135.S ml of 0.5 weight percent coagul~nt Calgon 2466 and 378.5 ~1 0.5 weight percent of flocculant Calgon 7736. The resulting mixture wa6 then mixed for 30 ~inutes and filtered u~ing the above noted filters in the order listed.
Table III show~ an antifreeze/coolant ~nd metals analysis of a spent antifreeze/coolant before treatment by the process of this invention. The analy6es were conducted by ICP
(Inductively Coupled Pla6ma3 ~naly~i~. Table6 IV and V show the result of ICP analysis of ~everal metals and ~ompounds in their soluble and insoluble forms both after a treatment ~tep according to the instant invention. Tables IV and V
demonstrate the effectivene~s of the instant proce66 in removing heavy metals, particularly lead and molybdenum, from spent antifreeze/coolant compositions. Referring to Table V, it is shown that in one embodiment of the instant process that after treatment the concentrations of the soluble forms of potassium, molybdenum, boron, iron, phosphoru6 ~nd 6illcon are reduced. Ths insoluble forms of aluminum, calcium, iron, magnesium, sodium, 6ilicon, phosphorus, lead and zinc were reduced. Further, reference to Table IV demonstrates the ability of the in~tant process to remove TTZ and benzoate as well as reduce the total ~uspended ~olids in the treated antifreeze/coolant.
It i6 particularly important to note that after treatment according to the invention that no detectable lead was present in the antifreeze/coolant down to the detection limit~ of ICP
analysi~ (le6s th~n about 2 ppm). Further, ~ince the antifreeze/coolant was passed through a 5 micrcn filter and the cation exchange resin (having an effective filter 6ize of 2.0 microns) the ~inal treated antifreeze/coolant meet6 current regulations of the Environmental Protection Agency for being a non-hazardous material on the basis of lead content~

~ ~ ~ ?' ~

(40 C.F.R. 261.24). Further, it ha6 been ob~erved that the form of the heavy ~etals in the instant precipitate i~ euch that the heavy ~etal~ are not leachable by water.

/\

/

r~

~L~
J~ ~TIFREEZE~COOLANT ~OME'OS~TION BEFO~E CHE~ICAL lrREATME
pH 9.42 EG Wt % 3 2 . 2 DEG Wt % 1.2 PG Wt % 0.6 Cl 25 so4 91 Benzoate 652 Volu-s ore 1n ~icro~r-~r p r ~1ll1lit-r; IID -~n~ not d t-ct-d et 2 pp~ or h I Dher B. SOLUBLE SPECIES EIEFORE TREATMEN~
EL13MENT A~:RA~E
Al ND
B 179.8 Ca ND
Cu ND
~e 11.5 K 334.9 Mg ND
Mo 9.7 Na 1509 . 0 p 464.0 Pb ND
- Si 70 . 7 Sn ND
Zn ND
Vslue~ re ~n ppm; ~ID ~ns not d~tected rt 2 p~n or hioh-r Ç._~NSOLUBLE SPECIES BEFORE ~EATMEN~
ELEMENT AVERAGE
Al 13.6 B 9.9 Ca 10.2 Cu ND
Fe B0.7 ~; . ND
3.5 l~o ND
Na 47.5 P 24.~
Pb 26.6 Si 10 . 7 ~;n ND
Zn 7.4 Velue~ re in ppn I~D ~eens ro~ detect-d ~ 2 pp~ or hi~her ~ 40 --TAB~
AFTER
AFTER CATION
ELEME~Tl AFTER ~0~ AF~ER 40~ CARBON AFTER 5~ EXCHANGE
~ASUB~P FILTER~ E~__ EII~E~ FIL~ER RESIN
Wt % EG(GC) 28.3 28.528.3 28.5 28.5 Wt ~ EG(RI) 29.9 30.029.8 30.0 30.0 pH 6.7 6.8 6.7 6.8 7.9 ~t % DEG l.OS 1.02 0.98 0.99 0.96 ~t ~ PG 0.51 0.51 0.51 0.4B 0.51 Cl 23 23 23 23 25 TTZ 2~6 235 90 101 61 ~ABLE V

MICRON BAG NICRON FILTER
SOL INS SOL INS
Al ND 131.7 ND 11.7 B 155.8 16.8 161.8 9.7 Ca ND 6.8 ND 4.0 Cu ND ND ND ND
Fe ND 32.2 ND ND
R 499.5 23.3 513.1 ND
Mg ND 2.0 ND ~D
~o 7.7 ND 8.1 ND
Na 1414 73.2 1434 21.6 P 190.9 1~1.2 194.7 7.8 Pb ND ND ND ND
~i 34.7 11.8 35.4 12.2 Sn ND ND ND ND
Zn ND 3.8 ND ND

~;J~ ~ 8 ~A~LE V (Continuea) AFTERAFTER S ~ICRON AFTER CATION
EL~MENT ~R~Q~ FI~TER EXCHANGE RESIN

Al ND 21.1 ND 3.2 ND 4.0 B 162.3 10.7 156.3 8.6 147.2 11.6 C~ 2.6 4.0 2.1 2.3 2.2 3.1 Cu ND ND ND ND ND ND
Fe ND 3.1 ND ND ND ND
K 526.7 ND 509.6 ND 252.3 ND
Mg ND ND ND ND N~ ND
~o 8.7 ND 8.3 ND ND ND
Na 14g5 27.1 1440 19.2 1962 29.3 P 205.1 18.6 199.0 ND 202.0 ND
Pb ND ND ND ND ND ND
Si 34.8 3.9 33.9 3.0 33.7 6.5 Sn ND ND ND ND ND ND
Zn ND ND ND ND ND ND

A spent antifreeze/coolant was obtained from a commercial establi~hment in the bu~iness of changing over ~pent antifreeze/cvolant from automobiles and trucks. A portion of spent antifreeze wa~ treated ~ccording to one of the following chemical treatments to demonstrate the effect of changes in the pH-ad~usting agent, precipitating agent, coagulant and flocculant on the treatment process. The coagulant in each treatment wa~ Calgon 2466 ~nd the flocculant was Calgon 7736. The treatment procecs was carried out and the analysis conducted as 6et forth, except a~ noted below in Example 2 for following ten (10) different chemical treatment~
and except the antifre~ze/coolant sa~ple ~ize which was treated was 500 milliliter6.

f J ~ 3 ~

T~EAT~NT
N0. ~HEMICAL TREAT~æ~T
1 The pH of the Ea~ple wa6 ad~u~ted to about 7.0 with org~ni~ ~cid (acet$c ac~d -CH3COOH, 9g.7~ ~olution); by treatment with 0.75 ~1 of org~nic acid ~ollowed by addition of 1.3 grams of Al (N03)3.9H20, ~ollowed by addit~on of 30 milliliter6 (ml) coagulant (0.25%
voluMe) ~olution, and then followed by addition o 10 ~1. of 0.25% flocculant ~olution.

2 The pH of the 6ample was ad~u6ted to about 7.0 with 1.9 grams of Ca(N03~2-2H2 (without addition of any pH adjusting a~ent, coagulant and flocculant).

3 The pH of the ~ample was adjusted to about 7.0 with 0.75 ml of inorganic ac~d (70 wt ~
nitric acid, followed by treatment with 1.3 grams of Al(N03)3.9H2o a8 the precipitating agent and then followed by addition of 30 ml of a 0. 25% 601ution of the coagulant.

4 The pH of the 6ample wa8 adjusted to about 7.0 with 0.75 ~1 of nitric acid solution (70 wt ~ HN03), followed by addition of 1.3 gram8 Al(N03)3.9H20 as a precipitating agent, followed by nddition of a 10 ml of 0.25 wt ~ solution of the ~locculant.

The pH of the ~ample was ad~usted to about 7.0 with 0.75 ~1, nitric acid aqueous ~olution (70 wt ~ HN03); followed by D-~5600 f~ f3 TREA ~ ENT '-' ~0 ~_ CHEMI~AL TREA~MENT
5 addltion o~ 1.3 gram~ of Al(N03)3.9H2O, (Cont.) follow~d by ~ddition of 10 ~1 of ~ 0.25 wt ~
agueou~ ~olution of the floccul~nt, and then followed by addition of 30 ~1 of a 0.25 wt %
solution (aqueou~) of the coagulant.

6 The pH of the ~a~ple wa~ ad~u~ted to a pH of ~bout 7.0 by addition of 0.75 ml of aqueou~
nitric ~cid t70 wt % HN03), followed by treatment with 1.3 grams Al(N03)3.9H20, ~ollowed by ~ddition of 10 ml of a 0.25 wt %
solution coagulant, and then 30 ml of the 0.25 wt % aqueous flocculant ~olution.

7 The pH of the sample W~6 adju6ted to about pH
7.0 with 0.75 ml aqueous nitric acid (70 wt %
HN03); ~nd then mixed with 1.3 gram~
Al(N03)3.9H20 follow~d by addition of 30 ml of a o.25 wt % aqueous solution of coagulant, and then followed by addition of 10 ml of a 0.25 wt % aguecus ~olution of flocculantO

8 The pH of the sample wa6 adju6ted to about-pH - -7.0 with 0.75 ml o~ nitric acid (70~ HN03);
followed by treatment with 1.3 grams Al(N03)3.9H20 follow~d ~y addition of 15 ~1 of a 0.5 wt % ~olution of coagulant and then follow~d by addition of 5 ~1 of a 0.5 wt %
solution of the flocculant.

9 The pH of the sample was adjusted to about pH
7.0 by addition of 0.7 ml of an aqueous for~ic ac~d 601ution (88% Formic acid - XCOOH) ~ollowed by addition of 1.3 grams of Al(N03)3.9H20, 2~

TREATMENT
N0. CH~MICAL TREATM~NT
9 ~ollowed by addition o~ 30 ml of a 25 wt %
(Cont) aqueous ~olution of ~oagulant, and then followed by addition of 10 ~1 of a 0.25 wt %
agueou~ ~olution of flocculant.

The 6ample was treated with 30 ~1 of ~ 0.25 wt % agueous solution of the coagulant and with 10 ml of a 0.25 wt % solution of the flocculant (comparative sample without pH-adjusting agent ~nd without precipitating agent).

Each of the above 6amples were then filtered through a 25 micron filter and the final treated ~ntifreeze~coolant snalyzed. The re~ults of the analyses are ~et ~orth in Table VI. Table VI
demonstrates that surprising result6 obtained by use of the adjustment of the pH to between about 4.0 nnd ~bout 7.5, the use of a precipitating agent and the use of ever~l concentrations of coagul~nt and flocculant.

5~L~
TREATMENT N0.
~NTROL~ 3 4 5 pH 9.1 5.87 7.5 5.54 5.18 5.39 Al , ppm 15.9 ND ND ND ~D ND
B , ppm 146.2 125 147 127 125 125 Ca , ppm 3.2 2.4 33.2 3.0 3.4 2~8 Fe , ppm 24.7 ND ND ND ND ND
g , ppm 640.0 506 604 483 522 ~90 ~g , ppm ND2 ND ND ND ND ND
Nc, ppm 16.7 12.3 12.8 11.9 12.4 12.1 Na , ppm 1471 1~19 1437 1366 1367 1331 P , ppm 444 142 61.9 139 137 140 Pb , ppm 19.7 ND ND ND ND ND
~i , ppm 109.344~7 55~2 44~5 45n9 39.8 Zn , ppm 7.2 ND ND ND ND ND

1 Ant~fr~eze/Cool~nt prior to ~re~t~ent ~ obtoin~d fro~
th~ eoo~in~ ~y~2~ of ut~obil~/truck~
2 ~D" ~eon6 not detectæd ~t 2 pp~ or hi~her TABLE VI (Continued~
TREATMENT ~0.
_~_ 7 8 9 1~
pH 5.41 5.55 5.25 5.13 9.1 Al , ppm ND ND ND ND 3 B j ppm 121 127.4 130.6 129.4 128 Ca , ppm ND 2.8 3.5 ND ND
F~ , ppm ND ND ND ND 3.0 , ppm 487 490.0 506.4 517.0 50~.0 ~g , pp~ ND ND ND ND ND : :
Mo , pp~ ND 11.8 12.2 ND 13.3 N~ , ppm 1350 1295 1365 1426 1210 P , ppm 136 141 147 139 331 Pb , ppm ND ND ND ND 2.8 8i , ppm ND 40.7 40.6 ND 42.0 Zn , ppm ND ND ND ND ND
The re6ults in Table VI demonstrate the ad~u6tm~nt of the pH ~nd use of the precipitating agent (e.g. ~reatment No~. 6 and 9) followed by addition of the coagulant ~nd flocculant wa6 ~ore effective than use of only the coagul~nt hnd flocculant ~e.g., Treat~ent No. 10), or by use - ~6 -L ~ ~ ~

of only Ca(N03)2.2~20 a6 the precipitating ~gent (Treat~ent No. 2). When ~ proce~ according to thi~
invention i~ employed (a~ $n Treatment Nos. 6 and 9) it i~ observed that the treated solution6 ~rom Treat~ent No~. 6 and 9 have reduced concentration6 of iron, ~olybdenum, silicon and zinc b~low detection li~its (2 ppm). Further, while both Treatments 6 ~nd 9 removed detectable ~olubilized lead, Treatment No.

10 (employing only coagulant a~d floccul~nt addition) gave a treated product containing 2.8 ppm Pb, 3.0 ppm Fe, 3.0 pp~ Al and 13.3 ppm Mo.

The process employed in example 3 (Treatment No.
7) was repeated using a propylene glycol-based antifreeze/coolant having the composition shown in Table VII. The propylene glycol-based antifreeze/coolant had been employed ns the antifreeze/coolant in an automotive cooling ~y~tem to provide the ~original used antifreeze/coolant"
employed in the instant example. The treatments with the pH-adjusting agent (HN03), precipitating agent (Al(N03)3.9H20), coagulant (Calgon 2466) ~nd flocculant (Calgon 7736) were conducted as described -in Example 3 to provide a treated propylene glycol-based antifreeze/coolant as shown in Table VII, bQlow. As ~hown in Table VII, the instant proces~ wa~
effective in removing an amount of potassium, phosphorus and Total Suspended Solids and from the original used antifreeze/coolant. Since the original used antifreeze/coolant did not contain several metal6 at detection levels ~bove ~bout 2 ppm, the removal of these ~etal6 by the process of this ~nvention could not be quantitatively evaluated.

~q ~A~

QPERTIES OF I~TIF R~E:ZE/COO~
ORIGINAL USED AFTER
ANTIFREEZE/COOL~ ~5=
pH 8.2 6.1 PG, % 52.5 49.8 TTZ 28 26. 0 ~enzoate ND ND

C~ 50 50 Al, ppm ND ND
B, ppm 367.1 . 307.4 Ca, ppm ND ND
Cu, ppm ND ND
Fe, ppm ND ND
X , ppm 94 59 . 5 ~g, ppm ND ND
Mo, ppm ND ND
Na, ppm 2083 ~759 P , ppm749 O 8 285 . 4 Pb, ppm ND ND
Si , ppm 57 48 . 8 Sn, ppm ND ND
Zn, ppm ND ND

-- 4~ --

Claims (56)

1. A process for the treatment of an aqueous composition containing between about 5 weight percent and about 95 weight percent of a polyhydric alcohol and containing at least one heavy metal wherein said process comprises:
(i) adjusting the pH of said aqueous composition to between about 4.0 and about 7.5 by addition of an effective amount of an pH adjusting agent to form a pH-adjusted composition and adding thereto an effective amount of a precipitating agent for said heavy metal.

2. A process according to claim 1 wherein said process comprises at least one of the following additional steps:
(ii) adding to the pH-adjusted composition an effective amount of coagulating agent and an effective amount of a flocculating agent to form a precipitate containing at least one heavy metal; and (iii) passing the pH-adjusted composition through a first filtration means to remove heavy metal-containing precipitate from said pH-adjusted composition.

3. A process according to claim 2 wherein said process comprises at least one of the following additional steps of:
(iv) passing said pH-adjusted composition of step (iii) through a second filtration means having an effective physical separation of greater than about 40 microns;
(v) passing the pH-adjusted composition from step (iv) through an organic separation means effective in removing organic compounds other than said polyhydric alcohol from said pH-adjusted composition;
(vi) passing said pH-adjusted composition through a third filtration means having an effective physical separation of greater than about 0.2 microns; and (vii) passing said pH-adjusted composition of step (vi) through an ion exchange effective in the removal of at least one solubilized heavy metal present in said pH-adjusted composition.

4. A process according to claim 3 wherein said process comprises at least one of the following additional steps:
(viii) passing said pH-adjusted composition of step (vii) through water removal means whereby between about 10 weight percent and about 100 weight percent of said water is removed from said pH-adjusted composition; and (ix) skimming a portion of said precipitate from said final pH adjusted composition of step (i).

5. A process according to claim 4 wherein said water removal means are distillation means.

6. A process according to claim 1 or claim 2 or claim 3 or claim 4 wherein said aqueous composition is a heavy metal-containing polyhydric alcohol-containing antifreeze/coolant taken from the cooling system of an internal combustion engine.

7. A process according to claim 6 wherein said polyhydric alcohol is ethylene glycol.

8. A process according to claim 7 wherein said ethylene glycol is present in an amount of between 5 and 95 volume percent.

9. A process according to claim 6 wherein said cooling system is an automotive cooling system and said heavy metal is at least one heavy metal selected from the group consisting of lead, molybdenum, iron, potassium, magnesium, zinc, copper and aluminum.

10. A process according to claim 1 or claim 2 or claim 3 or claim 4 wherein said polyhydric alcohol is selected from the group consisting of methanol, ethanol, propanol butanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, butene glycol, the monoacetate of propylene glycol, the monoethylether of glycerol, the dimethyl ether of glycerol, alkoxy alkanols and mixture thereof; with the preferred alcohols being selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol and mixtures thereof.

11. A process according to claim 10 wherein said polyhydric alcohol is selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol and mixtures thereof.

12. A process according to claim 4 wherein the pH
in step (i) is adjusted to between about 4.5 and about 7Ø

13. A process according to claims 1 or claim 2 or claim 3 or claim 4 wherein the pH-adjusting agent is at least one pH-adjusted agent selected from the group consisting of organic acids, inorganic acid acidic organic salts, acidic inorganic salts and mixtures thereof.

14. A process according to claim 13 wherein the pH-adjusting agent is selected from the group consisting of nitric acid phosphoric acid, sulfuric acid, hydrochloric acid, carboxylic acids and mixtures thereof.

15. A process according to claim 14 wherein said pH-adjusting agent is nitric acid.

16. A process according to to claim 1 or claim 2 or claim 3 or claim 4 wherein said precipitating agent is selected from the group consisting of chlorides, sulfates, phosphates, aluminum nitrates and mixtures thereof.

17. A process according to claim 2 or claim 3 or claim 4 wherein the flocculating agent is selected from the group consisting of Calgon 7736, Cyanimid 1820A and mixtures thereof.

18. A process according to claim 2 or claim 3 or claim 4 wherein the coagulating agent is selected from the group consisting of Calgon 2466, Cyanamid 572C and mixtures thereof.

19. A process according to claim 2 or claim 3 or claim 4 wherein flocculating agent is Calgon 7736 and the coagulating agent is Calgon 2466.

20. A process according to claim 2 or claim 3 or claim 4 wherein said coagulant has an effective amount between about 75 ppm and about 300 ppm and said flocculant has an effective amount between about 25 ppm and about 300 ppm.

21. A process according to claim 1 or claim 2 or claim 3 or claim 4 wherein said aqueous composition is obtained from a cooling system of an internal combustion engine contains 5 volume percent to 95 volume percent ethylene glycol, contains up to about 150 ppm lead, said pH-adjusting agent is nitric acid, said precipitating agent is A1(N03)3.9H20 said coagulant is present in an effective amount between about 75 ppm and about 300 ppm, said flocculant is present in an effective amount between about 25 ppm and about 300 ppm.

22. A process according to claim 1 or claim 2 or claim 3 or claim 4 wherein the treated pH-adjusted composition contains less soluble lead as compared to the untreated pH-adjusted composition.

23. A process according to claim 2 wherein said first filtration means is characterized as having effective separation for species greater than about 100 microns.

24. A process according to claim 2 or claim 3 or claim 4 wherein:
(a) said first filtration means is characterized by separation of species greater than 100 microns;
(b) said second filtration means is characterized by separation of species greater than 40 microns;
(c) said organic separation means is characterized as an activated carbon filter, (d) said third filtration means is characterized by separation of species greater than 5 microns; and (e) said ion-exchange means is a cation exchange means effective in selective removal of at least one heavy metal.

25. A process according to claim 1 or claim 2 or claim 3 or claim 4 wherein said process is carried out at an effective temperature between about 18°C and about 45°C and at an effective pressure.

26. A process for the treatment of an aqueous spent antifreeze/coolant composition obtained from the cooling system of internal combustion engines containing between about 5 weight percent and about 95 weight percent of a polyhydric alcohol selected from the group consisting of ethylene glycol, diethylene glycol and propylene glycol and containing at least one solubilized heavy metal species selected from the group consisting of lead, molybdenum, potassium, iron, zinc, copper and aluminum, wherein said process comprises the following steps:
(i) adjusting the pH of said aqueous composition to between about 4.0 and about 7.5 by addition of an effective amount of an pH adjusting agent to form a pH-adjusted composition and an effective amount of a precipitating agent effective in forming a precipitate of said heavy metal at an effective temperature and pressure;
(ii) adding to the said pH-adjusted composition an effective amount of at least one of a coagulating agent and a flocculating agent to form a heavy metal containing precipitate;
(iii) passing said pH-adjusted composition of step (ii) and said heavy metal containing precipitate through a first filtration means effective in removal of said heavy metal-containing precipitate having a size greater than about 100 microns;
(iv) passing said pH-adjusted composition of step (iii) through a second filtration means having an effective physical separation of greater than about 40.0 microns;
(v) passing the pH-adjusted composition from step (iv) through an organic separation means effective in removing organic compounds from said polyhydric alcohol of said pH-adjusted composition.
(vi) passing said pH-adjusted composition through a third filtration means having effective physical separation greater than about 5 microns; and (vii) passing said pH-adjusted composition of step (vi) through a cation exchnage means effective in the removal of at least one solubilized heavy metal species present in said pH-adjusted composition from step (vi).

27. A process according to claim 25 wherein said process comprises the additional step of:
(viii) passing said pH-adjusted composition of step (vii) through water removal means.

whereby between about 10 weight percent and about 100 weight percent of said water is removed from said pH-adjusted composition.

28. A process according to claim 27 wherein said water removal is distillation means.

29. A process according to claim 26 wherein said heavy metal is lead and said spent antifreeze/coolant taken from the cooling system of an internal combustion engine.

30. A process according to claim 26 or claim 29 wherein said polyhydric alcohol comprises a mixture of ethylene glycol and diethylene glycol.

31. A process according to claim 30 wherein said ethylene glycol is present in an amount of between 5 and 95 volume percent.

32. A process according to claim 26 wherein said cooling system is an automotive cooling system and said heavy metal is at least one heavy metal selected from the group consisting of lead, molybdenum, potassium, iron, zinc, magnesium, copper and aluminum.

33. A process according to claim 26 wherein said polyhydric alcohol is propylene glycol.

34. A process according to claim 26 wherein the pH in step (i) is between about 4.0 and about 7.5.

35. A process according to claim 26 wherein the pH-adjusting agent is at least one pH-adjusting agent selected from the group consisting of organic acids, inorganic acids, acidic organic salts, acidic inorganic salts and mixtures thereof.

36. A process according to claim 35 wherein the pH-adjusting agent is selected from the group consisting of nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid, carboxylic acids and mixtures thereof.

37. A process according to claim 36 wherein said pH-adjusting agent nitric acid.

38. A process according to claim 26 wherein said precipitating agent is selected from the group consisting of chlorides, sulfates, phosphates, aluminum nitrates, and mixtures thereof.

39. A process according to claim 26 wherein the flocculating agent is selected from the group consisting of Calgon 7736, Cyanamid 1820A and mixtures thereof.

40. A process according to claim 26 wherein the coagulating agent is selected from the group consisting of Calgon 2466, Cyanamid 572C and mixtures thereof.

41. A process according to claim 26 wherein flocculating agent is Calgon 7736 and the coagulating agent is Calgon 2466.

42. A process according to claim 26 wherein said coagulant has an effective amount between about 75 ppm and about 300 ppm and said flocculant has an effective amount between about 25 ppm and about 100 ppm.

43. A process according to claim 26 wherein said spent antifreeze/coolant composition contains 5 volume percent to 95 volume percent ethylene glycol, contains up to 250 ppm lead, said pH-adjusting agent is nitric acid, said precipitating agent is Al(NO3)3.9H2O
said coagulant is present in an effective amount between about 75 ppm and about 300 ppm and said flocculant is present in an effective amount between about 25 ppm and about 300 ppm.

44. A process according to claim 26 or claim 43 wherein the treated spent antifreeze/coolant composition contains less solubilized lead as compared to the untreated spent antifreeze/coolant composition.

45. a process according to claim 1 wherein said first filtration means is characterized by separation of species greater than 40 microns.

46. A process according to claim 26 wherein:
(a) said first filtration means is characterized by separation of species greater than 100 microns;
(b) said second filtration means is characterized by separation of species greater than 40 microns;
(c) said organic separation means is characterized as an activated carbon filter;
(d) said third filtration means is characterized by separation of species greater than 5 microns; and (e) said ion-exchange means is a cation exchange means effective in selective removal of at least one heavy metal.

47. A process according to claim 26 wherein said process is carried out at an effective temperature between about 18°C and about 45°C and at an effective pressure.

48. In a process for the removal of an antifreeze/coolant containing between about 5 wt % and about 95 wt % of a polyhydric alcohol and at least one heavy metal from the cooling system of an internal combustion engine and replacement of said antifreeze/coolant after treatment wherein said treatment comprises:
(a) adjusting the pH of said aqueous composition to between about 4.0 and about 7.5 by addition of an effective amount of an pH
adjusting agent to form a pH-adjusted composition and adding thereto an effective amount of a precipitating agent for said heavy metal;
(b) adding to the pH-adjusted composition an effective amount of coagulating agent and an effective amount of a flocculating agent to form a precipitate containing at least one heavy metal;
(c) passing the pH-adjusted composition through a first filtration means to remove heavy metal-containing precipitate from said pH-adjusted composition; and (d) adding to the filtered composition of step (c) an effective amount of an inhibitor package for said cooling system.

49. A process according to claim 48 wherein prior to step (d) at least one of the following steps is employed:

(1) passing said pH-adjusting composition through a second filtration means having an effective physical separation of greater than about 40 microns;

(2) passing the pH-adjusted composition through an organic separation means effective in removing organic compounds other than said polyhydric alcohol from said pH-adjusted composition;

( (3) passing said pH-adjusted composition through one or more additional filtration means having an effective mechanical separation of greater than about 0.2 microns; and (4) passing said pH-adjusted composition through an ion exchange effective in the removal of at least one solubilized heavy metal present in said pH-adjusted composition.

50. A process according to claim 48 or claim 49 wherein said aqueous composition is a heavy metal-containing ethylene glycol-containing antifreeze/coolant taken from the cooling system of an internal combustion engine.

51. A recycle apparatus comprising:
(i) holding means for holding an aqueous composition containing between about 5 weight percent and about 95 weight percent of a polyhydric alcohol containing at least one heavy metal;
(ii) pH adjusting means for adjusting the pH of said aqueous composition with a pH adjusting agent; and (iii) addition means for adding a precipitating agent to said aqueous composition.

52. A recycle apparatus comprises:
(i) holding means into which an aqueous composition containing between about 5 weight percent and about 95 weight percent of a polyhydric alcohol containing at least one heavy metal may be placed;
(ii) pH adjusting means for adjusting the pH of the aqueous composition in said holding means;
(iii) addition means for introducing into said holding means at least one of a precipitating agent, a coagulant and a flocculant;
(iv) pumping means for removing the aqueous composition from said holding means;
(v) mechanical separation means for removing solids from said aqueous ] composition based upon the size of * said solids;

(vi) organic separation means for removing one or more components of said aqueous composition on the basis of chemical reaction, chemical adsorption or chemical absorption; and (vii) ion exchange means effective in the removal by ion exchange at least one solubilized metal species in said aqueous composition.

53. A recycle apparatus comprises:
(i) holding means into which an aqueous composition containing between about 5 weight percent and about 95 weight percent of a polyhydric alcohol containing at least one heavy metal may be placed;
(ii) recirculating means for circulating aqueous composition in said holding means from a point below the surface of said aqueous composition to a point above the surface of said aqueous composition, whereby the recirculated aqueous composition contacts ambient air prior to its recirculation into said aqueous composition;
(iii) pH adjusting means for adjusting the pH of the aqueous composition in said holding means;
(vi) addition means for introducing into said holding means at least one of a precipitating agent, a coagulant and a flocculant; and (v) skimming means removing solids from the surface of said aqueous composition in said holding means

54. A recycle apparatus according to claim 53 wherein said apparatus additionally comprises at least one of:
(1) mechanical separation means for removing solids from said aqueous composition based upon the size of said solids;
(2) organic separation means for removing one or more components of said aqueous composition on the basis of chemical reaction, chemical adsorption or chemical adsorption; and (3) ion exchange means effective of at least removal by ion exchange of at least solubilized metal species in said aqueous composition.

55. A recycle apparatus according to claim 52 or claim 54 wherein said mechanical separation means comprises a:
(a) a first filtration means is characterized by separation of species greater than 100 microns;
(b) a second filtration means is characterized by separation of species greater than 40 microns; and (c) a third filtration means characterized by separation of species greater than 5 . microns.

56. A recycle apparatus according to claim 52 or claim 54 wherein said organic separation means is an activated carbon filter.