CN114345295A - Impurity removal process for chemical auxiliary - Google Patents
Impurity removal process for chemical auxiliary Download PDFInfo
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- CN114345295A CN114345295A CN202111556548.0A CN202111556548A CN114345295A CN 114345295 A CN114345295 A CN 114345295A CN 202111556548 A CN202111556548 A CN 202111556548A CN 114345295 A CN114345295 A CN 114345295A
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- chemical auxiliary
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- 238000000034 method Methods 0.000 title claims abstract description 53
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- 239000002245 particle Substances 0.000 claims abstract description 154
- -1 cation modified carbon Chemical class 0.000 claims abstract description 65
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 42
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 40
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000012752 auxiliary agent Substances 0.000 claims abstract description 25
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- 229920001220 nitrocellulos Polymers 0.000 claims abstract description 21
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- 235000009566 rice Nutrition 0.000 claims description 78
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- 238000001354 calcination Methods 0.000 claims description 14
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- 239000007864 aqueous solution Substances 0.000 claims description 13
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- 239000006185 dispersion Substances 0.000 claims description 12
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 9
- 239000004115 Sodium Silicate Substances 0.000 claims description 9
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 9
- 239000011230 binding agent Substances 0.000 claims description 9
- 229910001424 calcium ion Inorganic materials 0.000 claims description 9
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 9
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 9
- 239000003381 stabilizer Substances 0.000 claims description 9
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 claims description 8
- 108010010803 Gelatin Proteins 0.000 claims description 8
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 8
- 239000003063 flame retardant Substances 0.000 claims description 8
- 229920000159 gelatin Polymers 0.000 claims description 8
- 239000008273 gelatin Substances 0.000 claims description 8
- 235000019322 gelatine Nutrition 0.000 claims description 8
- 235000011852 gelatine desserts Nutrition 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- 239000000230 xanthan gum Substances 0.000 claims description 8
- 229920001285 xanthan gum Polymers 0.000 claims description 8
- 229940082509 xanthan gum Drugs 0.000 claims description 8
- 235000010493 xanthan gum Nutrition 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- 239000000020 Nitrocellulose Substances 0.000 claims description 7
- 239000004114 Ammonium polyphosphate Substances 0.000 claims description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 6
- 235000019826 ammonium polyphosphate Nutrition 0.000 claims description 6
- 229920001276 ammonium polyphosphate Polymers 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 230000004048 modification Effects 0.000 claims description 6
- 238000012986 modification Methods 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 239000012266 salt solution Substances 0.000 claims description 2
- 238000002360 preparation method Methods 0.000 description 30
- 238000001179 sorption measurement Methods 0.000 description 24
- 230000000694 effects Effects 0.000 description 12
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- 235000011187 glycerol Nutrition 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 9
- 238000005530 etching Methods 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 8
- 229910052710 silicon Inorganic materials 0.000 description 8
- 239000010703 silicon Substances 0.000 description 8
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 8
- 235000012431 wafers Nutrition 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 239000010903 husk Substances 0.000 description 6
- 239000011148 porous material Substances 0.000 description 6
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- 229910021641 deionized water Inorganic materials 0.000 description 5
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- 239000008202 granule composition Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 229910021529 ammonia Inorganic materials 0.000 description 4
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 4
- 229920002678 cellulose Polymers 0.000 description 4
- 239000001913 cellulose Substances 0.000 description 4
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Chemical compound [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 235000012239 silicon dioxide Nutrition 0.000 description 4
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 description 4
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
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- 238000010521 absorption reaction Methods 0.000 description 2
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- 238000000354 decomposition reaction Methods 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
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- RCEAADKTGXTDOA-UHFFFAOYSA-N OS(O)(=O)=O.CCCCCCCCCCCC[Na] Chemical compound OS(O)(=O)=O.CCCCCCCCCCCC[Na] RCEAADKTGXTDOA-UHFFFAOYSA-N 0.000 description 1
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- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical group O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 1
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- TUJKJAMUKRIRHC-UHFFFAOYSA-N hydroxyl Chemical compound [OH] TUJKJAMUKRIRHC-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Water Treatment By Sorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The application relates to the technical field of chemical auxiliary processing, and particularly discloses an impurity removing process for a chemical auxiliary. The impurity removal process of the chemical auxiliary agent comprises the following steps: (1) soaking the cation modified carbon particles in nitric acid, and then drying the cation modified carbon particles for later use; (2) uniformly mixing the crude chemical auxiliary agent and the cation modified carbon particles to obtain a mixed solution, and standing the mixed solution at room temperature; the crude chemical auxiliary agent is a diluent of acid nitrocotton wastewater or concentrated nitric acid prepared by a sulfuric acid method; (3) and after standing, concentrating and crystallizing the mixed solution, and filtering to remove filter residues to obtain the low-hybrid chemical assistant. The cation modified carbon particles adsorb sulfate ions in the crude chemical auxiliary agent, so that the purity of the crude chemical auxiliary agent is improved.
Description
Technical Field
The application relates to the technical field of chemical auxiliary processing, in particular to an impurity removal process for chemical auxiliary.
Background
Nitric acid is one of the most commonly used inorganic acids and is also an important chemical auxiliary agent, and etching liquid used for etching silicon wafers in the electronic industry usually contains nitric acid. Because the processing precision requirement of the silicon wafer is high, the silicon wafer is highly sensitive to impurities. When using nitric acid to prepare etching solution, a chemical plant needs to use concentrated nitric acid products with high purity as much as possible.
The preparation method of the concentrated nitric acid is divided into two methods, namely a direct nitration method for synthesizing the concentrated nitric acid by taking ammonia and air as raw materials, and a meta-nitration method for obtaining the concentrated nitric acid by taking the dilute nitric acid as a raw material and performing dehydration treatment. At present, the Mirabilitum method is a main production mode of domestic manufacturers. The meta-nitro method can be classified into a sulfuric acid method of dehydrating with concentrated sulfuric acid and a magnesium nitrate adsorption method of dehydrating with a magnesium nitrate solution, depending on the dehydrating agent used. When concentrated nitric acid is produced by a sulfuric acid process, a part of sulfate ions usually remain in the obtained concentrated nitric acid.
In view of the above-mentioned related art, the inventors believe that sulfate ions are difficult to remove in concentrated nitric acid prepared by a sulfuric acid process, and when a silicon wafer is processed using an etching solution prepared from concentrated nitric acid prepared by a sulfuric acid process, the sulfate ions introduced by the concentrated nitric acid cause deviation of actual components and theoretical components of the etching solution, which affects the precision of etching the processed silicon wafer.
Disclosure of Invention
In the related art, when a silicon wafer is processed using an etching liquid prepared from concentrated nitric acid by a sulfuric acid method, sulfate ions in the concentrated nitric acid affect the precision of processing the silicon wafer. In order to improve the defect, the application provides an impurity removal process of the chemical auxiliary agent.
The application provides a process for removing impurities of chemical auxiliary agents, which adopts the following technical scheme:
an impurity removal process for a chemical auxiliary agent comprises the following steps:
(1) soaking the cation modified carbon particles in nitric acid, and then drying the cation modified carbon particles for later use; the cation modified carbon particles are carbon particles adsorbed with divalent metal cations;
(2) uniformly mixing the crude chemical auxiliary agent and the cation modified carbon particles to obtain a mixed solution, and standing the mixed solution at room temperature; the crude chemical auxiliary agent is a diluent of acid nitrocotton wastewater or concentrated nitric acid prepared by a sulfuric acid method, and the mass fraction of sulfate ions in the crude chemical auxiliary agent is 1-5%;
(3) and after standing, concentrating and crystallizing the mixed solution, and filtering to remove filter residues to obtain the low-hybrid chemical assistant.
By adopting the technical scheme, the method uses nitric acid to carry out acidification treatment on the cation modified carbon particles, and the cation modified carbon particles firstly adsorb the nitric acid and then are mixed with the crude chemical auxiliary agent to form mixed liquid. In the mixed solution, the cation modified carbon particles adsorb sulfate ions and release nitrate ions into the mixed solution. Sulfate ions adsorbed in the cation modified carbon particles can generate electrostatic adsorption with divalent metal cations, so that the sulfate ions are fixed. Through the treatment of the cation modified carbon particles, sulfate ions in the crude chemical auxiliary are transferred to the cation modified carbon particles, so that the content of the sulfate ions in the crude chemical auxiliary is reduced, and the purification of the crude chemical auxiliary is realized. The purity of the concentrated nitric acid is improved after impurity removal, so that the precision of etching the silicon wafer can be better improved.
The impurity removal process can purify the dilute solution of the acidic nitrocotton wastewater besides purifying the concentrated nitric acid. The acidic nitrocotton wastewater is acidic waste liquid generated in the nitrocotton production process, and mainly comprises nitric acid, sulfuric acid and organic residues. After the acidic nitrocotton wastewater is diluted, through the impurity removal process, the cation modified carbon particles can not only adsorb sulfate ions, but also adsorb partial organic residues, and a purification solution containing a small amount of organic impurities is obtained. The purified liquid is oxidized or extracted to obtain dilute nitric acid with high purity, so that the chemical waste is recycled.
Preferably, the cation modified carbon particles are prepared according to the following method:
(1) drying and then slitting rice hulls to obtain rice hull particles, mixing the rice hull particles with a cation modification solution, and uniformly stirring to obtain a rice hull particle dispersion solution, wherein the cation modification solution is a salt solution containing divalent metal cations;
(2) removing water in the rice hull particle dispersion liquid to obtain cation modified rice hull particles, mixing and heating 60-80 parts of cation modified rice hull particles, 30-50 parts of mixing liquid, 8-12 parts of organic binder, 6-8 parts of flame retardant and 4-8 parts of stabilizer according to parts by weight, and uniformly stirring to obtain rice hull particle mixture; the liquid component with the highest content in the mixing liquid is water;
(3) and calcining the rice hull particle mixture to constant weight at the temperature higher than the burning point of the rice hulls, washing and drying the calcined product, and crushing to obtain the cation modified carbon particles.
Through adopting above-mentioned technical scheme, this application uses the mode production cation modified carbon particle of calcination, in calcination earlier stage, the moisture in the rice husk granule mixture takes place the vaporization to produce the pore structure in the rice husk granule mixture, the stabilizer has then increased the degree of consistency of pore distribution in the pore structure. In the later stage of calcination, the flame retardant hinders the combustion of organic matters, so that organic matters in the organic binder and the cation modified rice hull particles are dehydrated, the dehydrated products are combined with silicon dioxide in the rice hulls, and a porous carbonized structure is formed on the basis of the pore structure, so that the cation modified carbon particles are obtained.
Preferably, in the step (1) of preparing the cation modified carbon particles, cellulase is further added into the rice hull particle dispersion liquid after the rice hull particle dispersion liquid is obtained, and the weight ratio of the cellulase to the rice hull particles is 1: (100-120).
By adopting the technical scheme, one of the main components in the rice hull particles is cellulose, and the cellulose can be catalyzed by cellulase to decompose, so that the density of the rice hull particles is reduced, the prepared cation modified carbon particles are more loose and porous, and the adsorption effect of the cation modified carbon particles on sulfate ions is improved.
Preferably, the divalent metal cation is at least one of zinc ion and calcium ion.
By adopting the technical scheme, in the step (1) of preparing the cation modified carbon particles, the rice hull particles absorb zinc ions. In the step (3) of preparing the cation modified carbon particles, a porous carbon structure generated by calcining the rice hull particle mixture and zinc ions form coordinate bonds to obtain the cation modified carbon particles. The zinc ions can increase the porosity of the cation modified carbon particles and improve the adsorption performance of the cation modified carbon particles.
When the divalent metal cations in the cation modified solution simultaneously comprise calcium ions and zinc ions, the calcium ions can reduce the adsorption of the cellulase by the lignin in the rice hull particles, improve the effect of reducing the density of the rice hull particles by the cellulase, promote the absorption of the rice hull particles on the zinc ions, and contribute to improving the adsorption performance of the cation modified carbon particles.
Preferably, the organic binder is xanthan gum or gelatin.
By adopting the technical scheme, xanthan gum or gelatin can be used as an organic binder, wherein the caking property of the xanthan gum is superior to that of the gelatin, but the xanthan gum easily blocks air holes formed in the rice hull particle mixture in the initial calcining stage, so that the adsorption performance of cation modified carbon particles is reduced, and the adsorption effect of the cation modified carbon particles is better when the gelatin is used as the binder.
Preferably, the mixture is glycerol aqueous solution or ethanol aqueous solution.
By adopting the technical scheme, the glycerol aqueous solution and the ethanol aqueous solution can be used as a mixing solution, when the mixing solution is the ethanol aqueous solution, although the ethanol is easy to volatilize and remove, the boiling point of the ethanol is lower than that of water, so that in the calcining process, before the water is completely evaporated, the ethanol is converted into a gas state, the rice hull particle mixture is dried too fast, hardening occurs, and the formation of air holes in the rice hull particle mixture is influenced. When the mixture is a glycerol aqueous solution, as the boiling point of glycerol is far higher than that of water, water vapor firstly leaves the rice hull particle mixture until the temperature reaches the boiling point of the glycerol and then the glycerol is converted into a gas state, so that the time for keeping the rice hull particle mixture in a wet state is prolonged, the possibility of hardening of the rice hull particle mixture is reduced, and the adsorption performance of the cation modified carbon particles is improved.
Preferably, in the step (3) of preparing the cation-modified carbon particles, the calcined product is washed with phosphoric acid or hydrofluoric acid.
By adopting the technical scheme, phosphoric acid or hydrofluoric acid can increase the number of polar functional groups on the surface of the cation modified carbon particles, so that the cation modified carbon particles are activated. The hydrofluoric acid can also corrode residual silicon dioxide in the rice hull particles, so that the porosity of the cation modified carbon particles is increased, and the adsorption performance of the cation modified carbon particles is improved.
Preferably, the flame retardant is ammonium polyphosphate or red phosphorus.
Through adopting above-mentioned technical scheme, ammonium polyphosphate and red phosphorus all can generate phosphoric acid under the calcination condition, and phosphoric acid can hinder the diffusion of oxygen to play flame retardant efficiency, reduced the loss of cation modified carbon particle, phosphoric acid can also promote the rice husk granule mixture to dewater simultaneously, has accelerated the generation rate of cation modified carbon particle. Compare in red phosphorus, ammonium polyphosphate can also decompose and produce the ammonia, and the ammonia is the incombustible gas, not only can dilute oxygen to the ammonia can also form the gas pocket in rice husk granule mixture in the diffusion process, consequently helps improving the adsorption efficiency of cation modified carbon particle.
Preferably, the stabilizer is at least one of sodium silicate and sodium dodecyl sulfate.
By adopting the technical scheme, at the initial stage of calcining the rice hull particle mixture, air bubbles are formed in the rice hull particle mixture during water evaporation, at the moment, the hydrophobic section of the lauryl sodium sulfate extends into the gas phase in the air bubbles, and the hydrophilic end extends into the water phase which is not vaporized, so that the viscosity of a liquid film is increased, and the stability of the air bubbles is improved. When sodium silicate and sodium lauryl sulfate are used together as stabilizers, charring decomposition of the sodium lauryl sulfate already occurs at the later stage of the calcination of the rice hull particle mixture, while sodium silicate remains in the rice hull particle mixture. The sodium silicate is solidified due to heating and is combined with the silicon dioxide in the porous carbonized structure, so that the porous carbonized structure is supported, the possibility of collapse of the porous carbonized structure during calcination is reduced, and the adsorption performance of the cation modified carbon particles is improved.
Preferably, the crude chemical auxiliary is a diluent of acidic nitrocellulose waste water, the mass fraction of nitric acid in the diluent of the acidic nitrocellulose waste water is 5-10%, in the step (2) of the impurity removal process of the chemical auxiliary, iron powder and hydrogen peroxide are added into the mixed solution after the mixed solution is obtained, and the molar ratio of the hydrogen peroxide to the iron powder is (2.2-2.4): 1.
by adopting the technical scheme, after the acidic nitrocotton wastewater is diluted, the nitric acid in the acidic nitrocotton wastewater is diluted into dilute nitric acid with relatively weaker oxidizability, the reaction of the iron simple substance and the dilute nitric acid can generate ferrous nitrate, the ferrous nitrate and the hydrogen peroxide can generate the Fenton reaction, and the hydroxyl radical generated by the Fenton reaction can directly oxidize the organic residues in the acidic nitrocotton wastewater diluent into inorganic substances, so that the organic residues are cleaned, and the purity of the crude chemical auxiliary agent is improved.
1. According to the method, the cation modified carbon particles are used for adsorbing the crude chemical auxiliary agent, and when the crude chemical auxiliary agent is concentrated nitric acid prepared by a sulfuric acid method, the cation modified carbon particles can adsorb sulfate ions remained in the concentrated nitric acid to obtain the concentrated nitric acid with higher purity; when the crude chemical auxiliary is a diluent of acidic nitrocotton wastewater, the cation modified carbon particles can adsorb sulfate ions and part of organic residues, and finally obtain dilute nitric acid with higher purity, so that the chemical waste is recycled.
2. According to the method, the glycerol aqueous solution and the ethanol aqueous solution are preferably used as the mixing liquid for preparing the cation modified carbon particles, and compared with the ethanol aqueous solution, the glycerol aqueous solution can keep the rice hull particle mixture in a longer wet state, so that the possibility of hardening of the rice hull particle mixture is reduced, and the method is favorable for improving the adsorption performance of the cation modified carbon particles.
3. According to the method, when the crude chemical auxiliary is the diluent of the acidic nitrocotton wastewater, the iron powder and the hydrogen peroxide are added into the mixed liquid after the mixed liquid is obtained, and the organic residues in the mixed liquid are cleaned by the Fenton reaction, so that the purity of the crude chemical auxiliary is improved.
Detailed Description
The present application will be described in further detail with reference to examples.
The raw materials used in the preparation examples of the present application are all commercially available, wherein the rice hulls are provided by Yutaijia agricultural products Co., Ltd, and the cellulase is provided by Shandongxin Jiuchui chemical technology Co., Ltd.
Preparation example of cation-modified carbon particles
The following will explain preparation example 1 as an example.
Preparation example 1
In the present application, the cation-modified carbon particles are prepared according to the following method:
(1) dissolving zinc nitrate in deionized water to obtain a cation modified solution with the zinc ion concentration of 2mol/L for later use; drying the rice hulls, and then cutting the rice hulls into particles with the average particle size of 600 mu m to obtain rice hull particles for later use; mixing the rice hull particles and the cationic modification liquid according to the weight ratio of 1:5, and uniformly stirring to obtain rice hull particle dispersion liquid;
(2) filtering the rice hull particle dispersion liquid, drying filter residues to obtain cation modified rice hull particles, mixing and heating 60kg of cation modified rice hull particles, 30kg of mixing liquid, 8kg of organic binder, 6kg of flame retardant and 4kg of stabilizer to 70 ℃, and uniformly stirring to obtain a rice hull particle mixture; in the step, the mixture is ethanol water solution with 30 percent of ethanol mass fraction, the organic binder is xanthan gum, the flame retardant is red phosphorus, and the stabilizer is sodium dodecyl sulfate;
(3) heating the rice hull particle mixture from room temperature to 600 ℃ at the heating rate of 5 ℃/min, calcining the rice hull particle mixture to constant weight at 600 ℃, washing a calcined product by using deionized water, drying, and crushing the calcined product until the average particle size is 800 mu m to obtain the cation modified carbon particles.
As shown in Table 1, the production examples 1 to 5 were different in the amount of the raw materials for kneading the rice husk granule mixture.
TABLE 1
Preparation example 6
The difference between the preparation example and the preparation example 3 is that, in the step (1) of preparing the cation modified carbon particles, cellulase with enzyme activity of 100000U/g is added into the rice hull particle dispersion liquid after the rice hull particle dispersion liquid is obtained, and the weight ratio of the cellulase to the rice hull particles is 1: 100.
as shown in Table 2, the preparations 6 to 10 were different in the weight ratio of cellulase to rice husk granules.
TABLE 2
Preparation example 11
The difference between this preparation example and preparation example 8 is that, when preparing the cation-modified solution, only calcium nitrate was dissolved in deionized water to obtain a cation-modified solution having a calcium ion concentration of 2 mol/L.
Preparation example 12
The difference between the preparation example and the preparation example 11 is that zinc nitrate and calcium nitrate are dissolved in deionized water together to obtain a cation modified solution with a zinc ion concentration and a calcium ion concentration of 1 mol/L.
Preparation example 13
This preparation example differs from preparation example 12 in that xanthan gum was replaced with gelatin of the same weight.
Preparation example 14
The difference between the present production example and production example 13 is that the mixture was an aqueous glycerol solution containing 30% by mass of glycerol.
Preparation example 15
This production example is different from production example 14 in that in step (3) of producing cation-modified carbon particles, phosphoric acid having a concentration of 0.1mol/L was selected and washed on the calcined product.
Preparation example 16
This production example is different from production example 15 in that in the step (3) of producing cation-modified carbon particles, hydrofluoric acid having a concentration of 0.1mol/L was selected and used to wash the calcined product
Preparation example 17
This production example is different from production example 16 in that ammonium polyphosphate having an average polymerization degree of 45 was used in place of red phosphorus in a phosphorus atom molar ratio of 1: 1.
Preparation example 18
This preparation example is different from preparation example 17 in that the same weight of sodium silicate was used instead of sodium lauryl sulfate.
Preparation example 19
This preparation example is different from preparation example 17 in that the stabilizer includes 3kg of sodium lauryl sulfate and 3kg of sodium silicate.
Examples
The raw materials used in the examples of the present application are all commercially available, wherein the nitrocellulose waste water is provided by water balance and cellulose.
Examples 1 to 5
The following description will be given by taking example 1 as an example.
Example 1
In example 1, the process for removing impurities from a chemical auxiliary comprises the following steps:
(1) soaking the cation modified carbon particles of the preparation example 1 in 1mol/L nitric acid according to a solid-to-liquid ratio of 1:5 for 2 hours, then fishing out the cation modified carbon particles, and drying the cation modified carbon particles at 70 ℃ for later use;
(2) uniformly mixing the cation modified carbon particles and the crude chemical auxiliary agent according to the weight ratio of 1:4 to obtain a mixed solution, and standing the mixed solution at room temperature for 24 hours; the crude chemical auxiliary agent is concentrated nitric acid prepared by a sulfuric acid method, and the mass fraction of sulfate ions in the crude chemical auxiliary agent is 1.6%.
(3) And after standing, concentrating and crystallizing the mixed solution, and filtering to remove filter residues to obtain the low-hybrid chemical assistant.
As shown in Table 3, examples 1 to 19 differ mainly in the preparation examples of the cation-modified carbon particles.
TABLE 3
Example 20
The difference between the example and the example 19 is that the crude chemical auxiliary agent is a diluent of the acid nitrocotton wastewater, the mass fraction of sulfate ions in the diluent is 2.6%, and the mass fraction of nitrate ions is 8%.
Example 21
This example is different from example 20 in that, in step (2) of the impurity removal process, after the mixed solution is obtained, iron powder and hydrogen peroxide are further added to the mixed solution, the average particle size of the iron powder is 500 μm, the total weight of the hydrogen peroxide and the iron powder is 7.5% of the original weight of the mixed solution, and the molar ratio of the hydrogen peroxide to the iron powder is 2.1: 1.
as shown in Table 4, examples 21 to 25 differ in the molar ratio of hydrogen peroxide to iron powder.
TABLE 4
Comparative example
Comparative example 1
This comparative example differs from example 3 in that the same weight of activated carbon was used in place of the cation-modified carbon particles.
Comparative example 2
This comparative example differs from example 3 in that the cation-modified carbon particles were soaked with deionized water in step (1) of the impurity removal process.
Performance detection test method
For examples 1-20 and comparative examples 1-3,respectively detecting the initial sulfate ion mass fraction (w) of the crude chemical auxiliary0) And the mass fraction (w) of sulfate ions in the low-hybridization chemical auxiliary agent obtained after impurity removal1) Then, the sulfate ion removal rate was calculated according to the following formula.
The results of the calculation of the sulfate ion removal rate are shown in Table 5.
TABLE 5
For examples 20 to 25, the cod value (m) of the crude chemical auxiliary was measured using a WWH-CODcr type Industrial analytical cod Detector supplied by Wuxi Vol instruments science and technology Ltd0) And cod value (m) of low hybrid chemical adjuvant1) Then, the cod removal rate was calculated according to the following formula.
The calculation results of cod removal rate are shown in Table 6.
TABLE 6
| Sample(s) | cod removal rate/%) |
| Example 20 | 36.8 |
| Example 21 | 85.4 |
| Example 22 | 88.3 |
| Example 23 | 91.4 |
| Example 24 | 91.7 |
| Example 25 | 91.9 |
Combining examples 1-5 and comparative example 1 and table 5, it can be seen that the removal rate of sulfate ions measured in examples 1-5 is higher than that in comparative example 1, which indicates that the cation modified carbon particles of the present application form a porous carbonized structure on the basis of the pore structure, and thus have better adsorption effect than the existing activated carbon. The removal rate of the sulfate ions measured in the examples 1 to 5 is more than 70%, which shows that most of the sulfate ions in the crude chemical auxiliary are transferred to the cation modified carbon particles after the treatment of the cation modified carbon particles, so that the content of the sulfate ions in the concentrated nitric acid is reduced, and therefore, the impurity removal process can effectively remove the sulfate ions remained in the concentrated nitric acid by the sulfuric acid method on the market.
Combining example 3 and comparative example 2 with table 5, it can be seen that the removal rate of sulfate ions measured in example 3 is higher than that in comparative example 2, which shows that the acidification treatment of the cation-modified carbon particles with nitric acid in the present application helps to improve the adsorption effect of the cation-modified carbon particles on sulfate ions.
It can be seen by combining example 3 and examples 6-10 with table 5 that the removal rates of sulfate ions measured in examples 6-10 are all higher than that in example 3, which indicates that cellulase can catalyze the decomposition of cellulose, thereby reducing the density of rice hull particles, making the prepared cation modified carbon particles more loose and porous, and contributing to improving the adsorption effect of the cation modified carbon particles on sulfate ions.
Combining example 8, examples 11-12 and table 5, it can be seen that example 11 measured a lower sulfate ion removal rate than example 8, indicating that zinc ions have a better effect on improving the adsorption performance of the cation-modified carbon particles than calcium ions. In example 12, when the calcium ions and the zinc ions jointly treat the rice hull particles, the calcium ions can reduce the adsorption of the cellulase by the lignin in the rice hull particles, so that the effect of reducing the density of the rice hull particles by the cellulase is improved, the absorption of the rice hull particles to the zinc ions is promoted, and the adsorption performance of the cation-modified carbon particles is improved.
Combining example 13, example 12 and table 5, it can be seen that the removal rate of sulfate ions measured in example 13 is higher than that in example 12, indicating that gelatin does not easily block the pores formed in the mixture of rice hull particles at the initial stage of calcination, and therefore replacing xanthan gum with gelatin contributes to improving the adsorption effect of the cation-modified carbon particles.
It can be seen from the combination of examples 13 and 14 and table 5 that the removal rate of sulfate ions measured in example 14 is higher than that in example 13, which shows that the glycerin aqueous solution prolongs the time for keeping the rice hull particle mixture in a wet state, reduces the possibility of hardening of the rice hull particle mixture, and is beneficial to improving the adsorption performance of the cation modified carbon particles.
Combining example 14, examples 15-16 and table 5, it can be seen that the removal rate of sulfate ions measured in examples 15 and 16 is higher than that in example 14, which indicates that phosphoric acid and hydrofluoric acid can increase the number of polar functional groups on the surface of the cation-modified carbon particles, so as to activate the cation-modified carbon particles and improve the adsorption performance of the cation-modified carbon particles. The measured sulfate ion removal rate of example 16 is higher than that of example 15, indicating that hydrofluoric acid increases the porosity of the cation-modified carbon particles by etching the silicon dioxide, further improving the adsorption performance of the cation-modified carbon particles.
It can be seen from the combination of example 16 and example 17 and table 5 that the removal rate of sulfate ions measured in example 17 is higher than that in example 16, which shows that ammonia gas generated by decomposing ammonium polyphosphate can form air holes in the mixture of rice hull particles during the diffusion process, thereby being helpful for improving the adsorption performance of cation modified carbon particles.
When example 17, examples 18 to 19 and table 5 are combined, it can be seen that the removal rates of sulfate ions measured in example 17 and example 18 are close to each other, indicating that the stabilizing effects of sodium silicate and sodium lauryl sulfate are close to each other when the weights are the same. The removal rate of sulfate ions measured in example 19 was higher than in examples 17 and 18, indicating that the effect of sodium silicate and sodium lauryl sulfate when used together was superior to that when used alone.
Combining example 20, example 3 and table 5, it can be seen that the removal rate of sulfate ions measured in example 20 is slightly higher than that in example 3, which indicates that the impurity removal process of the present application also has a better purification effect on the dilute solution of acidic nitrocotton wastewater.
As can be seen from the combination of example 20, examples 21 to 25 and Table 6, in example 20, the cation-modified carbon particles adsorbed organic residues, thereby lowering the cod value of the acidic nitrocellulose waste water dilution. In examples 21 to 25, ferrous nitrate and hydrogen peroxide, which can be generated by the reaction of the elemental iron with the dilute nitric acid, can undergo a fenton reaction, and hydroxyl radicals generated by the fenton reaction oxidize the organic residue, so that the organic residue is cleaned, the cod value is reduced, and the purity of the acidic nitrocellulose wastewater diluent is improved.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (10)
1. The impurity removal process of the chemical auxiliary is characterized by comprising the following steps of:
(1) soaking the cation modified carbon particles in nitric acid, and then drying the cation modified carbon particles for later use; the cation modified carbon particles are carbon particles adsorbed with divalent metal cations;
(2) uniformly mixing the crude chemical auxiliary agent and the cation modified carbon particles to obtain a mixed solution, and standing the mixed solution at room temperature; the crude chemical auxiliary agent is a diluent of acid nitrocotton wastewater or concentrated nitric acid prepared by a sulfuric acid method, and the mass fraction of sulfate ions in the crude chemical auxiliary agent is 1-5%;
(3) and after standing, concentrating and crystallizing the mixed solution, and filtering to remove filter residues to obtain the low-hybrid chemical assistant.
2. The process for impurity removal of chemical assistants of claim 1, wherein the cationic modified carbon particles are prepared according to the following method:
(1) drying and then slitting rice hulls to obtain rice hull particles, mixing the rice hull particles with a cation modification solution, and uniformly stirring to obtain a rice hull particle dispersion solution, wherein the cation modification solution is a salt solution containing divalent metal cations;
(2) removing water in the rice hull particle dispersion liquid to obtain cation modified rice hull particles, mixing and heating 60-80 parts of cation modified rice hull particles, 30-50 parts of mixing liquid, 8-12 parts of organic binder, 6-8 parts of flame retardant and 4-8 parts of stabilizer according to parts by weight, and uniformly stirring to obtain rice hull particle mixture; the liquid component with the highest content in the mixing liquid is water;
(3) and calcining the rice hull particle mixture to constant weight at the temperature higher than the burning point of the rice hulls, washing and drying the calcined product, and crushing to obtain the cation modified carbon particles.
3. The impurity removal process of a chemical auxiliary according to claim 2, wherein in the step (1) of preparing the cation-modified carbon particles, cellulase is further added to the rice hull particle dispersion liquid after the rice hull particle dispersion liquid is obtained, and the weight ratio of the cellulase to the rice hull particles is 1: (100-120).
4. The process of claim 2, wherein the divalent metal cation is at least one of zinc ion and calcium ion.
5. The process of claim 2, wherein the organic binder is selected from xanthan gum or gelatin.
6. The process for removing impurities from chemical auxiliary agents according to claim 2, wherein the mixing solution is glycerol aqueous solution or ethanol aqueous solution.
7. The process for removing impurities from chemical assistants according to claim 2, wherein in the step (3) of preparing the cation-modified carbon particles, the calcined product is washed with phosphoric acid or hydrofluoric acid.
8. The impurity removal process of a chemical auxiliary according to claim 2, wherein the flame retardant is ammonium polyphosphate or red phosphorus.
9. The process of claim 2, wherein the stabilizer is at least one of sodium silicate and sodium dodecyl sulfate.
10. The impurity removal process of a chemical auxiliary according to claim 1, wherein the crude chemical auxiliary is a dilute solution of acidic nitrocellulose waste water, the mass fraction of nitric acid in the dilute solution of acidic nitrocellulose waste water is 5 to 10%, in the step (2) of the impurity removal process of a chemical auxiliary, iron powder and hydrogen peroxide are further added to the mixed solution after the mixed solution is obtained, and the molar ratio of the hydrogen peroxide to the iron powder is (2.2 to 2.4): 1.
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