JPH0199679A - Method for fixing heavy metals in soil or solid waste - Google Patents

Abstract

PURPOSE:To make heavy metals or heavy metal compds. insoluble and to prevent pollution by the metals by adding an aq. soln. of a specified metal capturing agent to soil or solid waste contg. the heavy metals or heavy metal compds. CONSTITUTION:An aq. soln. of a metal capturing agent having -RX [where X is COOH and R is (CH2)n (n is an integer of 1-4), CH2CH(CH3) or CH2CH (CH2COOH)] or a salt thereof, a hydroxyalkyl group, at least one dithiocarboxy group, etc., as substituents for active hydrogen atoms. in polyamines per 1mol. of the polyamines is prepd. and added to soil or waste solid contg. heavy metals or heavy metal compds. The heavy metals or heavy metal compds. are fixed and made insoluble.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for immobilizing heavy metals in solid waste such as soil, EP ash, and heavy metal sludge.

[Conventional technology and Problems that the invention attempts to solve]

In recent years, as the pollution of rivers, oceans, etc. by wastewater from factories has become a problem, regulations to prevent pollution by wastewater have been strengthened, and it is now mandatory to keep metals contained in wastewater below a specified concentration. Particularly strict regulations are in place for heavy metals that are harmful to the human body, such as mercury, cadmium, zinc, lead, copper, and chromium. For this reason, various methods have been proposed to remove metals from wastewater. For example, after adding alkali to wastewater to convert metals into hydroxides, the metals are coagulated and precipitated using a polymer flocculant. A neutralization coagulation-sedimentation method for removal is known, but there is a problem that the generated heavy metal hydroxide sludge may re-dissolve depending on how it is disposed of, causing secondary pollution.

In addition, factories that produce heavy metals and their compounds have been disposing of waste containing heavy metals and their compounds for a long time by filling them in concrete and dumping them in landfills. A problem has arisen in which small amounts of soil and its compounds have been leached out over many years and contaminated the soil.

[Means for solving problems]

The present invention was made in view of the above points, and is a soil that can prevent heavy metal pollution by immobilizing heavy metals contained in solid waste such as soil, sludge, and EP ash and making them water-insoluble. Another object of the present invention is to provide a method for immobilizing heavy metals in solid waste.

That is, the present invention provides -RX(
However, X is C0OH, R is (CH2), (however, n
is an integer from 1 to 4), CH2Cll(CH3), or C
1(2-CH(C112-COoH) ) or a salt thereof, or at least one hydroxyalkyl group, and at least one dithiocarboxy group or a salt thereof as a substituent. Heavy metals in soil or solid waste, characterized by adding an aqueous solution of the above to soil or solid waste containing heavy metals or their compounds to insolubilize the heavy metals or their compounds in the soil or solid waste. The gist of this article is the immobilization method of the following types.

The metal scavenger used in the present invention includes polyamines and a monohalogenated carboxylic acid whose halogen-substituted alkyl group has 1 to 4 carbon atoms or an unsaturated carboxylic acid whose unsaturated alkyl group has 2 to 4 carbon atoms. Let it react (CII
2), C00II group, CH2Cl (CH3)-C0
0I+ group, or CHzCIl (CHzCOOtl
) After introducing a carboxylic acid derivative group such as a C0OH group,
Either react with carbon disulfide to introduce a dithiocarboxy group, or react with carbon disulfide to form a dithiocarboxy group, and then react with a monohalogenated carboxylic acid or an unsaturated carboxylic acid (C11□ ) n C
0OH group, CHzCH(CH3)C0OH group, CHzC
! Compounds obtained by introducing carboxylic acid derivative groups such as I(CHz-COOH)COoH groups; ring-opening addition of epoxyalkanes to polyamines to introduce hydroxyalkyl groups such as β-hydroxyalkyl groups as N-substituents Compounds obtained by reacting carbon disulfide and introducing a dithiocarboxy group, or reacting polyamines with carbon disulfide, and then ring-opening and adding an epoxyalkane to introduce a hydroxyalkyl group; In the same way as (C
H2)-C0OH group, CH, Cl-(CH3)C00H
group, or CH2Cl! (CIl□C00H)COO
A compound obtained by introducing at least one carboxylic acid derivative group such as 11 groups, at least one hydroxyalkyl group, and at least one dithiocarboxy group; or the above (CI+2) -C0011 group, Cll2CH(
C1+3)-C00H group, CHzCH(CHzCOOl
l) Compounds having a salt of a carboxylic acid derivative group such as a COoH group, or a salt of a dithiocarboxy group as a substituent.

The above polyamines refer to an imino group or an amino group formed by bonding one or two active hydrogen atoms to a nitrogen atom.
For example, ethylenediamine,
Propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, diethylenetriamine, triethylenetetramine, tripropylenetetramine, tributylenetetramine, tetraethylenepentamine, tetraethylenepentamine, tetrabutylenepentamine, pentaethylenehexamine, etc. polyalkylene polyamine; phenylene diamine, xylene diamine, metaxylene diamine, iminobispropylamine, monomethylaminopropylamine, methyliminobispropylamine, 1,3-bis(
(aminomethyl) cyclohexane, 3,5-diaminochlorobenzene, melamine, 1-aminoethylpiperazine,
Examples include piperazine, diaminophenyl ether, 3,3'-dichlorobenzidine, tolidine base, m-1-lylene diamine, and polyethylene polyimine (preferably having an average molecular weight of 300 or more). In addition to the polyamines mentioned above, N which can be obtained by reacting these polyamines with alkyl halides or fatty acids
-Alkyl polyamines, N-acyl polyamines, etc. can also be used. N-alkylpolyamines include N-alkylethylenediamine, N-alkylpropylenediamine, N-alkylhexamethylenediamine,
N-alkylphenylenediamine, N-alkylxylenediamine, N-alkyldiethylenetriamine, N-
Alkyltriethylenetetramine, N-alkyltetraethylenepentamine, N-alkylpentaethylenehexamine, etc. can be used. The number of carbon atoms in the N-substituted alkyl group is preferably 2 to 18. The acyl group of the N-acylpolyamine preferably has 2 to 24 carbon atoms, and examples of the acyl group include an acetyl group, a propionyl group, a butyryl group, a caproyl group, a lauroyl group, an oleoyl group,
Examples include myristyroyl group, stearoyl group, beheroyl group, and the like.

Furthermore, polycondensed polyamines obtained by polycondensing these polyamines with epihalohydrins such as epichlorohydrin, epibromohydrin, epiiodohydrin, and bromomethyloxirane can also be used. These polyamines can be used alone or in combination of two or more. In addition, polycondensation with epihalohydrin is (C1h)nC0
011 group, C11zCIl(CH:+)COOH group, C
HzCH (CHzCOOll) After introducing a substituent such as a carboxylic acid derivative group such as a C0OH group or a hydroxyalkyl group or a salt thereof, at least one of these substituents
It can be carried out in any reaction process after introducing a species and a dithiocarboxy group or a salt thereof, or after introducing only a dithiocarboxy group or a salt thereof as a substituent.

(CH2), CO Kanoki, C11ZCII (CI(:+
) COOH Kyo, or CH2CII (CH2COOH
) Examples of monohalogenated carboxylic acids and unsaturated carboxylic acids used to introduce carboxylic acid derivative groups such as CO groups include monochloroacetic acid, monochloropropionic acid, monochlorobutyric acid, acrylic acid, methacrylic acid, itaconic acid, etc. can be mentioned. Preferred epoxyalkanes used for introducing hydroxyalkyl groups are ethylene oxide, propylene oxide,
Examples of the hydroxyalkyl group introduced in butylene oxide and α-olefin oxide having 6 to 28 carbon atoms include hydroxyethyl group, hydroxypropyl group, hydroxybutyl group, β-hydroxydodecyl group, β-hydroxytetradecyl group, Examples include β-hydroxyhexadecyl group, β-hydroxyoctadecyl group, β-hydroxydioctacyl group, and the like.

The above (CH2)IICOOtl group, CH□Cll (C
H3) CO base, or C11□CH (CIIzC
OOtl) Salts of carboxylic acid derivative groups such as COOII groups and dithiocarboxy groups include alkali metal salts such as potassium salts, sodium salts, and lithium salts; alkaline earth metal salts such as calcium salts, magnesium salts, and barium salts; ammonium salts; Examples include salt. Methods for introducing these salt-type substituents include the above-mentioned halogenated carboxylic acid,
A method in which a salt of an unsaturated carboxylic acid is reacted with polyamines, after introducing an acid type substituent such as (C11□)n C0OH group, alkali metal hydroxide, alkaline earth metal hydroxide, ammonia, etc. A method of treating with an alkali, or a method of reacting a halogenated carboxylic acid, an unsaturated carboxylic acid, and a polyamine in the presence of an alkali, or a method of treating with an alkali in place of the halogenated carboxylic acid, unsaturated carboxylic acid, or a salt thereof. Examples include a method in which a lower alcohol ester such as methyl acid is used to form the acid type substituent or its salt by saponification, acid decomposition, or the like. In addition, methods for introducing a salt of a dithiocarboxy group as a substituent include reacting carbon disulfide to introduce a dithiocarboxy group, and then treating it with an alkali similar to the above, or adding carbon disulfide in the presence of an alkali. One example is a method of causing a reaction.

Above, (C112)fiCOOH group, C11□CH(C
I-13) COOII group, CHzCIl (CHzCOO
H) Carboxylic acid derivative groups such as COOtl groups or their salts, dithiocarboxy groups or their salts, and hydroxyalkyl groups are usually N-substituents bonded to the nitrogen atom of polyamines, but they can be polycondensed with epihalohydrin as polyamines. When a polycondensed polyamine is used, the dithiocarboxy group or its salt does not only bond to the nitrogen atom, but also replaces the hydrogen atom of the hydroxyl group that occurs in the epihalohydrin skeleton and bonds to the oxygen atom. It's okay.

In the method of the present invention, the aqueous solution of the metal scavenger is applied to soil or EP.
It is added to solid waste such as ash and heavy metal sludge to immobilize heavy metals or their compounds in soil or solid waste, but if the water content in soil or solid waste is too low, metals The reaction between the scavenger and heavy metals becomes incomplete,
On the other hand, if the water content is too high, the workability of waste treatment after immobilization will deteriorate, so the total amount of water originally contained and water due to the addition of the metal scavenger aqueous solution will be 10 to 90%. It is preferable to adjust the concentration and amount of the metal scavenger aqueous solution so as to maintain the concentration within a certain range.

The metal scavenger aqueous solution may be simply sprinkled on the surface of the soil or solid waste, but it is preferable to knead it after being sprayed or simply added.

The metal scavenger used in the present invention has particularly excellent scavenging properties for heavy metals such as mercury, cadmium, zinc, copper, chromium, arsenic, gold, silver, platinum, vanadium, and thallium, and particularly contains the above heavy metals or their compounds. It is effective for treating soil or solid waste.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples 1 to 7 Aqueous solutions of metal scavengers obtained by reacting polyamines shown in the same table with carboxylic acids and carbon disulfide at the molar ratios shown in Table 1 (the metal scavenger concentrations are shown in Table 1). Also shown.

) was added in an amount of 10 mj2 per 100 g of treatment sludge (6% water content) and stirred and kneaded for 15 minutes using a universal stirring mixer (Kodaira Seisakusho type). The treatment sludge was subjected to an elution test using water with a pH of 5.8 according to the method specified in the Environment Agency Notification No. 13, and the eluate was analyzed using the JIS KO102 method. As a result, the metal ion concentration in the eluate was found to be the same as that of water. SJ? 0.50ppm, cadmium 0.25ppm
, chromium 2. OI) pm.

A similar elution test was conducted on the treated sludge, and the eluted heavy metals were analyzed using the same method. The results are shown in Table 3.

Examples 8 to 14 Aqueous solutions of metal scavengers obtained by reacting hydroxyalkyl polyamines shown in Table 2 with carbon disulfide at the molar ratios shown in Table 2 (concentrations of metal scavengers are shown in Table 2) .) The same treatment sludge as in Examples 1 to 7 was treated in the same manner. The sludge after treatment was subjected to an elution test and an analysis of eluted heavy metals in the same manner as in Examples 1 to 7. The results are also shown in Table 3.

Comparative Example 1 Aqueous solution of metal scavenger obtained by reacting 1 mole of ethylenediamine with 2 moles of carbon disulfide (metal scavenger concentration 1 wt%)
The sludge was treated under the same conditions as in the example. The treated sludge was subjected to an elution test and analysis in the same manner as in the examples, and the results are also shown in Table 3.

Table 2 Table 3 *I Polycondensed polyamine obtained by polycondensing N-(β-hydroxyoctyl)triethylenetetramine and 1 mole of epichlorohydrin.

In addition, Example 1.2.4.5.6.7.9.10.11.
For the metal scavenger in Example 12.13, both the carboxylic acid derivative group and the dithiocarboxy group were used as sodium salts, and in Example 3.8.14, they were used as they were in the acid form.

〔Effect of the invention〕

As explained above, according to the method of the present invention, soil, EP,
It is possible to reliably immobilize hazardous heavy metals in solid waste such as heavy metal sludge and prevent their elution, and prevent heavy metals from entering the soil and seawater from solid waste disposed of underground, II6, etc. It is possible to reliably prevent the transfer of heavy metals present in Furukawa and soil into living organisms. In addition, in the method of the present invention, in addition to the dithiocarboxy group, di(Ctlz),
IC0011 group, CllCl+-(C113)COOH
By using a carboxylic acid derivative group such as a CHZCII (CIl□C00II) Co group, or a salt thereof, or a hydroxyalkyl group as a substituent, heavy metals in water-containing sludge or their It also has the effect of exhibiting excellent fixation properties against salt.

Claims (3)

[Claims] (1) Per polyamine molecule, the substituent substituted with the active hydrogen atom of the polyamine is -RX (where X is COOH and R is (CH_2)_n [
However, n is an integer from 1 to 4], CH_2CH (CH_3)
, or CH_2CH-(CH_2COOH)) or a salt thereof, or an aqueous solution of a metal scavenger having at least one hydroxyalkyl group and at least one dithiocarboxy group or a salt thereof as a substituent. , fixation of heavy metals in soil or solid waste, characterized by adding to soil or solid waste containing heavy metals or their compounds to insolubilize the heavy metals or their compounds in the soil or solid waste. method. (2) The method for immobilizing heavy metals according to claim 1, wherein the solid waste is EP ash or heavy metal sludge. (3) The metal scavenger has at least one alkyl group or acyl group as the N-substituent bonded to the nitrogen atom of the polyamine.
A method for immobilizing heavy metals according to claim 1 or 2, which comprises a species.