Summary of the invention
The objective of the invention is to overcome the deficiency that exists on the existing nano titanic oxide sol technology of preparing, a kind of preparation method of sol of high active Nano titanium dioxide is provided, utilizes nano titanic oxide sol crystallization degree height, transmittance height, the anti-microbial activity of this method preparation good.
A kind of preparation method of sol of high active Nano titanium dioxide comprises the steps:
(1) take by weighing titanyl sulfate or titanium sulfate, be dissolved in water, dripping alkali liquid is regulated pH greater than 8, fully stirs;
(2) filter, washing precipitation till the sulfate radical-free ion, and then with the distilled water repetitive scrubbing to neutrality;
(3) precipitation is added water mixing, making beating, then slurry is transferred to the thermostatically heating reactor, add the water mixing, drip acid solution, making pH is 0.5~2.0, and normal temperature fully stirs down;
(4) slurry was stirred 3~60 hours down in 40~95 ℃, promptly get nano titanic oxide sol with certain crystallization degree;
(5) nano titanic oxide sol that will have certain crystallization degree is transferred in the airtight withstand voltage reactor, and pressure-controlling is 1 * 10
5~5 * 10
6Pa, temperature is controlled between 50~300 ℃, and be 0.5~20 hour heat-up time, promptly gets sol of high active Nano titanium dioxide.
In above-mentioned preparation method, the described pressure-controlling of step (5) preferred 10
5~10
6Pa.
In above-mentioned preparation method, antibiotic and the mildew-resistant ability for the sterilization that improves nano titanic oxide sol, can carry out noble metal loading to nano titanium oxide handles, its concrete grammar is: add precious metal salt solution in the gained nano titanic oxide sol, placed under the UV-light radiation then 0.5~10 hour, constantly stir simultaneously, wherein deposition should be between 0.1~5%.The salts solution of the preferred gold and silver of described precious metal salt solution, platinum, palladium or rhodium.
In above-mentioned preparation method, in order to reduce the content of nano titanic oxide sol impurity, improve transmittance, reduce electron-hole recombination, can carry out dialysis or nanofiltration processing to nano titanic oxide sol, molecular weight is dammed in dialysis should be between 5000~20000, and dialyzate is selected the pure water of pH between 6~8 for use, and finally regulate the pH value less than 7, to guarantee the stability of colloidal sol.
In above-mentioned preparation method, the preferred sodium hydroxide of the described alkali lye of step (1), potassium hydroxide or ammoniacal liquor.
In above-mentioned preparation method, the preferred hydrochloric acid of the described acid solution of step (3), nitric acid, acetic acid or phosphoric acid; The best is nitric acid or hydrochloric acid.
Compared with prior art, the present invention has following beneficial effect:
1. the TiO 2 sol of the present invention's preparation is light blue, and odorlessness does not contain organism.
2. the TiO 2 sol good stability of the present invention's preparation can not flocculate or precipitate after placement for a long time or the dilution.
3. the TiO 2 sol of the present invention's preparation improves through high pressure water thermal treatment post crystallization degree, the active raising.
4. the TiO 2 sol of the present invention's preparation significantly reduces through dialysis processing rear impurity content, and transmittance improves, and easily causes the surface deposition impurity minimizing of electron-hole recombination or disappears active raising.
5. the TiO 2 sol of the present invention preparation is handled the antibiotic and mildew-proof function of back sterilization through noble metal loading and is significantly improved, and the especially dark attitude or the low light level improve more obvious down.
6. the TiO 2 sol of the present invention's preparation is neutral, can not cause any corrosion to base material, and is applied widely.
7. preparation process technology of the present invention is simple, is convenient to operation, and can require to produce the product of different qualities according to difference, thereby is easy to carry out scale operation.
Embodiment
Below by embodiment the present invention is further specified.
Embodiment 1. is with titanyl sulfate high pressure water hot preparation TiO 2 sol
Take by weighing titanyl sulfate, add water and be stirred to transparently, dropping sodium is regulated more than the pH to 9, continues to stir more than 2 hours, filtration washing (detects with the titration of 0.5M barium chloride solution) till the sulfate radical-free ion repeatedly then, and then with the distilled water repetitive scrubbing to neutrality.At last filter cake is added water mixing, making beating, then slurry is transferred to the thermostatically heating reactor with double-jacket, add the water mixing, drip acid solution then, making pH is 1.2, and normal temperature stirs more than 2 hours down.Carry out dispergation then, slurry in 75 ℃ of following heated and stirred, is promptly obtained having the nano titanic oxide sol of certain crystallization degree after 24 hours; It is transferred in the airtight withstand voltage reactor then, pressure-controlling is 5 * 10
5Pa, temperature is controlled at 140 ℃, and be can obtain nano titanic oxide sol in 2,4,6 or 8 hours heat-up time.Its transmittance changing conditions as shown in Figure 1, the result shows that transmittance slightly descends along with prolong airtight heat-up time, therefore, therefore, will improve the crystallization degree of sol particle on the one hand by the high pressure hydro-thermal; Can not superheated become muddy even precipitation on the other hand to prevent colloidal sol.
The purification and impurity removal and the pH regulator of the TiO 2 sol of embodiment 2. high pressure Hydrothermal Preparation take by weighing titanyl sulfate, adding water is stirred to transparent, dropping ammonia is regulated more than the pH to 9, continue to stir more than 2 hours, filtration washing (detects with the titration of 0.5M barium chloride solution) till the sulfate radical-free ion repeatedly then, and then with the distilled water repetitive scrubbing to neutrality.At last filter cake is added water mixing, making beating, then slurry is transferred to the thermostatically heating reactor with double-jacket, add the water mixing, drip acid solution then, making pH is 1.0, and normal temperature stirs more than 2 hours down.Carry out dispergation then, slurry in 65 ℃ of following heated and stirred, is promptly obtained having the nano titanic oxide sol of certain crystallization degree after 20 hours; It is transferred in the airtight withstand voltage reactor then, pressure-controlling is 10
6Pa, temperature is controlled at 160 ℃, and be 1 hour heat-up time, can obtain nano titanic oxide sol.Adopt dialysis mode (its dam molecular weight should between 8000~12000), remove foreign ion (as nitrate ion, sulfate ion, ammonia radical ion etc.) wherein, it is 6 pure water that dialyzate is selected pH for use, and finally regulates the pH value and should be 5 to guarantee the stability of colloidal sol.
The spectroscopic analysis and the structural analysis of the TiO 2 sol before and after embodiment 3. purification and impurity removals
In order to show the performance variation of handling front and back among the embodiment 2 by dialysis, we have carried out XRD to it, the test of ultraviolet-visible light transmittance spectrum and infrared (FTIR).Fig. 2 is the XRD spectra before and after the TiO 2 sol dialysis, and the result shows before the dialysis except the diffraction peak of anatase octahedrite, to also have several very sharp-pointed diffraction peaks (shown in S among the figure), the reference standard collection of illustrative plates, and it is by NaNO as can be known
3, Na
2SO
4Crystallization Deng sodium salt (NaX) causes, and this is that dispergator (nitric acid) and raw material residual impurity in the preparation process causes.And after the dialysis (shown in After among the figure), these impurity diffraction peaks all weaken greatly even disappear, and the diffraction peak of anatase octahedrite is very clear.
Fig. 3 is the transmittance spectrogram before and after the TiO 2 sol dialysis.The result shows that the transmittance in the zone of colloidal sol more than 350nm obviously improves after the dialysis, and this shows that the dialysis processing also can reduce the particle diameter of colloidal particle simultaneously and then improve transmittance in removal of impurities, and this more helps colloidal sol and in use improves quality of forming film.
Fig. 4 is the infrared spectrum (FTIR) before and after the TiO 2 sol dialysis.The result shows that colloidal sol is at 1385cm after the dialysis
-1The peak area that (the coupled vibration peak that produces for nitrate radical) located reduces greatly, this show dialysis handle removed most of because of adding the nitrate ion that dispergator is introduced; In addition, 835cm
-1, 1789cm
-1, 2423cm
-1The several little vibration peak at place also weakens after dialysis is handled or disappears, this shows that the dialysis processing has significantly reduced the deposition of surface impurity species, help reducing the compound of the electron hole of causing because of impurity in the light-catalyzed reaction process, and then improve reactive behavior.
The specific activity that the TiO 2 sol of embodiment 4. high pressure Hydrothermal Preparation and normal pressure prepare colloidal sol
The photochemical catalysis gas reactor that volume is 33.4L is adopted in this experiment, and built-in three ultraviolet lamps (Philips, 8W, 365nm).Catalyzer is apart from fluorescent tube 1.5cm.Gas to be measured is not thiomethyl alcohol, adopts thiomethyl alcohol transmitter (the Detcon DM-100-CH of Teco Corp.
3SH) test concentrations.Appropriateness is controlled at 52 ± 2% in the experimentation, and temperature is controlled at 25 ± 1 ℃, and catalyst levels 0.5g, area are 18cm * 26cm, and this catalyzer was in 70 ℃ of dryings 24 hours before the test.The active comparative result that the TiO 2 sol and the normal pressure of high pressure Hydrothermal Preparation prepared colloidal sol as shown in Figure 5, clearly, colloidal sol after the high pressure water thermal treatment is active obviously to be improved, degradation rate constant improves above 30%, this mainly is because high pressure water thermal treatment can improve the crystallization degree of nanoparticle, and then improves that it is active.
The TiO 2 sol of embodiment 5. precious metal deposition of silver high pressure Hydrothermal Preparation
Take by weighing titanyl sulfate, add water and be stirred to transparently, dripping alkali liquid is regulated more than the pH to 9, continues to stir more than 2 hours, filtration washing (detects with the titration of 0.5M barium chloride solution) till the sulfate radical-free ion repeatedly then, and then with the distilled water repetitive scrubbing to neutrality.At last filter cake is added water mixing, making beating, then slurry is transferred to the thermostatically heating reactor with double-jacket, add the water mixing, drip acid solution then, making pH is 1.0, and normal temperature stirs more than 2 hours down.Carry out dispergation then, slurry in 65 ℃ of following heated and stirred, is promptly obtained having the nano titanic oxide sol of certain crystallization degree after 20 hours; It is transferred in the airtight withstand voltage reactor then, pressure-controlling is 10
6Pa, temperature is controlled at 160 ℃, and be can obtain nano titanic oxide sol in 1 hour heat-up time.Add silver nitrate solution then in the pure colloidal sol that has prepared, placed under the UV-light radiation then 4 hours, constantly stir simultaneously, wherein deposition is 0.8%.
If will improve the pH value and the removal foreign ion (as nitrate ion, sulfate ion, sodium ion or ammonia radical ion etc.) wherein of colloidal sol, need to adopt modes such as dialysis or nanofiltration (it is minimum dam molecular weight should less than 5000), and finally regulate pH value should be less than 7 stability with assurance colloidal sol.
The corrosion test of front and back to canned bottle handled in embodiment 6. diasolysises
Test method:
Canned bottle is an aluminum alloy material, and whole bottle does not have the slit of welding and pressing, and test material is the colloidal sol that acidic sol (handling without dialysis) and purifying treatment are crossed.
Process of the test is as follows: the colloidal sol that a certain amount of acidic sol and purifying treatment are crossed is poured into respectively in A, the B jar, seal with preservative film, be placed on homo(io)thermism in 60 ℃ water-bath, observed corrosion situation and the colloidal sol outward appearance and the transmittance changing conditions of canned bottle every 24 hours.
Through about 60 days viewing tests, obtain test-results:
(1) since the 7th day, corrosion phenomenon at first appearred in the A bottle, and the colloidal sol transmittance descends in the bottle, and muddy sign is arranged; By the 10th day, colloidal sol was relatively more muddy, and deposited phenomenon occurs;
(2) arrive the 8th day, corrosion phenomenon does not take place in B bottle inside, and colloidal sol outward appearance and transmittance all do not have considerable change in the bottle;
When (3) arriving 15 days, in the A bottle corrosion comparatively serious, colloidal sol is precipitation substantially fully, has therefore ended the test of A bottle, still do not have considerable change in the B, and the colloidal sol outward appearance still keeps good;
(4) arrive the 45th day, all do not see obvious corrosion in the B bottle, colloidal sol still keeps stable and does not precipitate, and colloidal sol does not still have considerable change in the B bottle;
(5) arrive the 60th day, all do not see obvious corrosion in the B bottle, colloidal sol still keeps stable and does not precipitate, and colloidal sol does not still have considerable change in the B bottle.
The sterilization effect evaluation of embodiment 7. precious metal deposition of silver TiO 2 sols
Test foundation and analytical procedure: antibacterial and bactericidal property and stability test method with reference to appendix C product among the GB 15979-2002, the gene test method among the QB/T2591-2003.
Test microbes: colon bacillus, streptococcus aureus, Pseudomonas aeruginosa and e coil k 1 pneumonia germ.
Test condition:
25 ℃ of a, culture temperature.
UV-light activation colloidal sol and substratum mixed system are 1 hour before b, the inoculation.Inoculate bacterial classification to be measured then, cultivate in the incubator.Do the blank experiment simultaneously
Be calculated as follows the antibacterium rate:
Pure TiO
2Colloidal sol and deposition of silver TiO
2The anti-microbial activity result such as the following table of colloidal sol:
Table 1 anti-microbial property detected result
By data in the table 1 as seen, deposition of silver TiO
2Colloidal sol all is higher than pure TiO to the anti-microbial activity of colon bacillus, streptococcus aureus, Pseudomonas aeruginosa and these four kinds of bacterium of e coil k 1 pneumonia germ
2Colloidal sol can reach complete germ-resistant effect substantially in 24 hours.
Embodiment 8. deposition of silver TiO
2The mildew-resistant level estimate of colloidal sol
Test bacterial classification: mix the mould bacterial classification, comprise aspergillus niger (Aspergillus niger) ATCC16404, flavus (Asp.flavus) GIM3.17, Sai Shi aspergillus (Asp.sydowii) GIM1.01, terreus (Asp.terreus) GIM3.34, Aspergillus ustus (Asp.ustus) GIM3.40, bud branch mould (Chaetomium herbarum) GIM3.57, paecilomyces varioti (Paecilomycesvarioti) GIM3.385, Chaetomium globosum (Chaetomium globasum) GIM3.52, Penicillium citrinum (penicillium citrinum) GIM3.100, viride (Trichoderma viride) GIM3.139.
Incubation time: 14 days, ultraviolet activated 1 hour (control experiment does not activate) before the process of the test, and conventional incubator is cultivated.
Assessment by mould proof ability has constituted the mildew-resistant grade, judges by following index:
0---no mildew
1---the mildew spot is in 1 millimeter, and it is sparse to distribute;
2---the mildew spot is in 2 millimeter or spread and be grown in 2 millimeters scopes, mildew maximum 1/4th of the whole surface that is no more than that distributes;
3---the mildew spot accounts for 1/4th of whole surface in 2 millimeter or distribution;
4---the mildew spot is covered with mycelia on more than 5 millimeters or whole surface.
The second stage of pilot scale TiO of table 2
2Colloidal sol mildew-resistant level estimate
Table 2 result shows that if activate through ultraviolet before the catalyst experiment, the mildew-resistant grade of two kinds of colloidal sols has all reached 0 grade, promptly sprayed colloidal sol after, its surface in contact is mildew no longer all, this shows that this colloidal sol product has good mildew-resistant effect under certain photoirradiation.If activate through ultraviolet before the catalyst experiment, pure colloidal sol is owing to reduced activity under the low light level, so the growth of mould fungus inhibition fully, its mildew-resistant grade is 1 grade; And Ag depositing Ti O
2Colloidal sol but still has good anti-mold effect, and its mildew-resistant grade is 0 grade, i.e. mildew not, and this mainly is because surface deposition silver itself has very high bacteriostatic activity, this explanation Ag deposition has improved TiO
2The antimold activity of colloidal sol not only has good anti-mold effect, even also can well play a role under no optical condition under high light, can be widely used in the place of each different illumination intensity.