CN114345295B - Impurity removal process for chemical auxiliary agent - Google Patents
Impurity removal process for chemical auxiliary agent Download PDFInfo
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- CN114345295B CN114345295B CN202111556548.0A CN202111556548A CN114345295B CN 114345295 B CN114345295 B CN 114345295B CN 202111556548 A CN202111556548 A CN 202111556548A CN 114345295 B CN114345295 B CN 114345295B
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- 239000000126 substance Substances 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 47
- 239000012752 auxiliary agent Substances 0.000 title claims abstract description 39
- 239000012535 impurity Substances 0.000 title claims abstract description 33
- 239000002245 particle Substances 0.000 claims abstract description 149
- -1 cation modified carbon Chemical class 0.000 claims abstract description 62
- 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 37
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000011259 mixed solution Substances 0.000 claims abstract description 24
- 239000000243 solution Substances 0.000 claims abstract description 23
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- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 10
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- 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
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- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 8
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- 235000010493 xanthan gum Nutrition 0.000 claims description 8
- 239000004114 Ammonium polyphosphate Substances 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 7
- 235000019826 ammonium polyphosphate Nutrition 0.000 claims description 7
- 229920001276 ammonium polyphosphate Polymers 0.000 claims description 7
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- 102000004190 Enzymes Human genes 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 3
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- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 239000012266 salt solution Substances 0.000 claims description 2
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- 208000002430 Multiple chemical sensitivity Diseases 0.000 abstract 1
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- 235000019333 sodium laurylsulphate Nutrition 0.000 description 9
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 8
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- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 4
- 238000003763 carbonization Methods 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
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 description 4
- 208000005156 Dehydration Diseases 0.000 description 3
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- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 3
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- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 2
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- Water Treatment By Sorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The application relates to the technical field of processing of chemical aids, and particularly discloses an impurity removal process of a chemical aid. The impurity removal process of the chemical auxiliary agent comprises the following steps: (1) Soaking the cation modified carbon particles by using nitric acid, and then drying the cation modified carbon particles for standby; (2) Uniformly mixing the crude chemical auxiliary agent and the cationic modified carbon particles to obtain a mixed solution, and standing the mixed solution at room temperature; the crude chemical auxiliary agent is dilute solution of acidic nitrocotton wastewater or concentrated nitric acid prepared by sulfuric acid; (3) And after standing, concentrating and crystallizing the mixed solution, and filtering to remove filter residues to obtain the low-impurity chemical auxiliary agent. 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 processing of chemical additives, in particular to an impurity removal process of a chemical additive.
Background
Nitric acid is one of the most commonly used inorganic acids and is also an important chemical auxiliary agent, and etching solutions used for etching silicon wafers in the electronic industry generally contain nitric acid. Because the processing precision of the silicon wafer is high, the silicon wafer is highly sensitive to impurities. In preparing etching solutions using nitric acid, chemical plants need to use concentrated nitric acid products of high purity as much as possible.
The preparation method of the concentrated nitric acid is divided into two methods, namely a direct-nitrate method for synthesizing the concentrated nitric acid by taking ammonia and air as raw materials and a indirect-nitrate method for obtaining the concentrated nitric acid by taking dilute nitric acid as raw materials through dehydration treatment. At present, the m-nitro method is a main production mode of domestic factories. Depending on the dehydrating agent used, the meta-nitro method can be classified into a sulfuric acid method using concentrated sulfuric acid for dehydration and a magnesium nitrate adsorption method using a magnesium nitrate solution for dehydration. When concentrated nitric acid is produced by a sulfuric acid process, a portion of sulfate ions typically remain in the resulting concentrated nitric acid.
In view of the above-mentioned related art, the inventors believe that in the concentrated nitric acid prepared by the sulfuric acid method, sulfate ions are difficult to remove, and when a silicon wafer is processed using an etching solution prepared by the sulfuric acid method, the sulfate ions introduced by the concentrated nitric acid may cause deviation of actual components of the etching solution from theoretical components, affecting the accuracy of etching the processed silicon wafer.
Disclosure of Invention
In the related art, when a silicon wafer is processed using an etching solution prepared from concentrated nitric acid by sulfuric acid method, sulfate ions in the concentrated nitric acid affect the accuracy of processing the silicon wafer. To ameliorate this disadvantage, the present application provides an impurity removal process for a chemical adjuvant.
The impurity removing process of the chemical auxiliary agent adopts the following technical scheme:
an impurity removal process of a chemical auxiliary agent comprises the following steps:
(1) Soaking the cation modified carbon particles by using nitric acid, and then drying the cation modified carbon particles for standby; the cation modified carbon particles are carbon particles adsorbed with divalent metal cations;
(2) Uniformly mixing the crude chemical auxiliary agent and the cationic modified carbon particles to obtain a mixed solution, and standing the mixed solution at room temperature; the crude chemical auxiliary agent is dilute solution of acidic 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-impurity chemical auxiliary agent.
By adopting the technical scheme, the method of the application uses nitric acid to acidify the cation modified carbon particles, the cation modified carbon particles firstly adsorb the nitric acid, and then the nitric acid and the crude chemical auxiliary agent are mixed into mixed liquid. In the mixed solution, the cation modified carbon particles adsorb sulfate ions and release nitrate ions into the mixed solution. The sulfate ions adsorbed in the cation modified carbon particles can be electrostatically adsorbed with divalent metal cations, thereby realizing the fixation of the sulfate ions. Through the treatment of the cation modified carbon particles, sulfate ions in the crude chemical auxiliary agent are transferred into the cation modified carbon particles, so that the sulfate ion content in the crude chemical auxiliary agent is reduced, and the purification of the crude chemical auxiliary agent is realized. The purity of the concentrated nitric acid is improved after impurity removal, so that the precision of etching the processed silicon wafer can be better improved.
The impurity removal process can purify the dilute liquid of the acidic nitrocotton wastewater besides the concentrated nitric acid. The acidic nitrocotton wastewater is an acidic waste liquid generated in the nitrocotton production process, and comprises the main components of 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 adsorb sulfate ions and part of organic residues, so that a purified liquid containing a small amount of organic impurities is obtained. The dilute nitric acid with higher purity can be obtained after the purification liquid is subjected to oxidation treatment or extraction, so that the recycling of chemical waste is realized.
Preferably, the cationically modified carbon particles are prepared as follows:
(1) Drying rice hulls, then cutting to obtain rice hull particles, mixing the rice hull particles with a cation modified liquid, and uniformly stirring to obtain rice hull particle dispersion liquid, wherein the cation modified liquid 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, and mixing, heating and uniformly stirring 60-80 parts by weight of cation modified rice hull particles, 30-50 parts by weight of mixing liquid, 8-12 parts by weight of organic binder, 6-8 parts by weight of flame retardant and 4-8 parts by weight of stabilizer to obtain rice hull particle mixture; the liquid component with the highest content in the mixing liquid is water;
(3) Calcining the rice hull particle mixture to constant weight at a temperature higher than the ignition point of the rice hull, washing and drying the calcined product, and crushing to obtain the cation modified carbon particles.
Through adopting above-mentioned technical scheme, the mode that uses the calcination produces cation modified charcoal granule in this application, and in the early stage of calcination, the moisture in the rice husk granule mixture takes place to vaporize to produce the pore structure in the rice husk granule mixture, the stabilizer then has 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 the organic matters in the organic binder and the cation modified rice husk particles are dehydrated, the dehydrated product is combined with silicon dioxide in the rice husk, and a porous carbonization structure is formed on the basis of a pore structure, thereby obtaining the cation modified carbon particles.
Preferably, in the step (1) of preparing the cation modified carbon particles, after the rice hull particle dispersion liquid is obtained, cellulase is further added into the rice hull particle dispersion liquid, and the weight ratio of the cellulase to the rice hull particles is 1 according to the enzyme activity of the cellulase of 100000U/g: (100-120).
By adopting the technical scheme, one of the main components in the rice hull particles is cellulose, and the cellulose can catalyze the decomposition of the cellulose, 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, the porous carbon structure generated by calcining the rice hull particle mixture forms coordination bonds with zinc ions, thereby obtaining 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 divalent metal cations in the cation modifying liquid comprise calcium ions and zinc ions at the same time, the calcium ions can reduce the adsorption of lignin in rice hull particles to cellulase, improve the effect of the cellulase on reducing the density of the rice hull particles, promote the absorption of the rice hull particles to the zinc ions, and help to improve the adsorption performance of the cation modified carbon particles.
Preferably, the organic binder is xanthan gum or gelatin.
By adopting the technical scheme, the xanthan gum or the gelatin can be used as the organic binder, wherein the cohesiveness of the xanthan gum is better than that of the gelatin, but the xanthan gum is easy to block the air holes formed by the rice husk granule mixture at the initial stage of calcination, so that the adsorption performance of the cation modified carbon granules is reduced, and the adsorption effect of the cation modified carbon granules is better when the gelatin is used as the binder.
Preferably, the mixing liquid is glycerol water solution or ethanol water solution.
By adopting the technical scheme, the glycerol aqueous solution and the ethanol aqueous solution can be used as the mixing solution, and when the mixing solution is the ethanol aqueous solution, ethanol is easy to volatilize and remove, but 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 gaseous 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 glycerin water solution, because the boiling point of glycerin is far higher than that of water, vapor firstly leaves the rice husk particle mixture until the temperature reaches the boiling point of glycerin, and then the glycerin is converted into a gaseous state, so that the time for keeping the rice husk particle mixture in a wet state is prolonged, the possibility of hardening the rice husk 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, phosphoric acid or hydrofluoric acid is selected to wash the calcined product.
By adopting the technical scheme, the number of polar functional groups on the surfaces of the cation modified carbon particles can be increased by phosphoric acid or hydrofluoric acid, so that the cation modified carbon particles are activated. The hydrofluoric acid can also corrode the 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.
By adopting the technical scheme, the ammonium polyphosphate and the red phosphorus can generate phosphoric acid under the calcination condition, and the phosphoric acid can block the diffusion of oxygen, so that the flame retardant effect is achieved, the loss of cation modified carbon particles is reduced, meanwhile, the phosphoric acid can also promote the rice husk particle mixture to be dehydrated, and the generation rate of the cation modified carbon particles is accelerated. Compared with red phosphorus, ammonium polyphosphate can be decomposed to generate ammonia, the ammonia is nonflammable gas, oxygen can be diluted, and air holes can be formed in rice husk particle mixture in the diffusion process of ammonia, so that the adsorption performance of the cation modified carbon particles can be improved.
Preferably, the stabilizer is at least one of sodium silicate and sodium dodecyl sulfate.
Through adopting above-mentioned technical scheme, at the initial stage of calcining rice husk granule mixture, form the bubble in the rice husk granule mixture when the moisture evaporates, the hydrophobic section of sodium dodecyl sulfate stretches into the vapor phase in the bubble this moment, and hydrophilic end stretches into the aqueous phase that does not take place the vaporization, has increased the viscosity of liquid film, has improved the stability of bubble. When sodium silicate and sodium lauryl sulfate are used as stabilizers at the same time, sodium lauryl sulfate has been carbonized and decomposed at the later stage of calcining 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 carbonization structure, so that the porous carbonization structure is supported, the possibility of collapse of the porous carbonization structure during calcination is reduced, and the adsorption performance of the cation modified carbon particles is improved.
Preferably, the crude chemical auxiliary agent is a diluent of acidic nitrocotton wastewater, the mass fraction of nitric acid in the diluent of the acidic nitrocotton wastewater is 5-10%, in the step (2) of the impurity removal process of the chemical auxiliary agent, after the mixed solution is obtained, iron powder and hydrogen peroxide are further added into the mixed solution, and the molar ratio of the hydrogen peroxide to the iron powder is (2.2-2.4): 1.
through the adoption of the technical scheme, after the acidic nitrocotton wastewater is diluted, nitric acid in the acidic nitrocotton wastewater is diluted into dilute nitric acid with relatively weak oxidizing property, iron simple substance and the dilute nitric acid react to generate ferrous nitrate, the ferrous nitrate and hydrogen peroxide can generate Fenton reaction, and hydroxyl radicals generated by the Fenton reaction can directly oxidize organic residues in the acidic nitrocotton wastewater diluent into inorganic matters, so that the cleaning of the organic residues is realized, and the purity of crude chemical additives is improved.
1. According to the method, the cationic modified carbon particles are used for carrying out adsorption treatment on the crude chemical auxiliary agent, and when the crude chemical auxiliary agent is concentrated nitric acid prepared by a sulfuric acid method, the cationic modified carbon particles can adsorb sulfate ions remained in the concentrated nitric acid to obtain concentrated nitric acid with higher purity; when the crude chemical auxiliary agent is the diluent of the acidic nitrocotton wastewater, the cationic modified carbon particles can adsorb sulfate ions and part of organic residues, and finally dilute nitric acid with higher purity is obtained, so that the recycling of chemical waste is realized.
2. According to the method, the glycerol aqueous solution and the ethanol aqueous solution are preferably used as the mixing solution 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 moist state, so that the possibility of hardening of the rice hull particle mixture is reduced, and the adsorption performance of the cation modified carbon particles is improved.
3. According to the method, when the crude chemical auxiliary agent is the diluent of the acidic nitrocotton wastewater, iron powder and hydrogen peroxide are added into the mixed solution after the mixed solution is obtained, and organic residues in the mixed solution are cleaned by utilizing Fenton reaction, so that the purity of the crude chemical auxiliary agent is improved.
Detailed Description
The present application is described in further detail below with reference to examples.
The raw materials used in the preparation examples of the application can be obtained through the market, wherein rice hulls are provided by Yutai Jia agricultural products Co., ltd, and cellulase is provided by Shandong Xin Jiu Cheng Chemie Co., ltd.
Preparation example of cation-modified carbon particles
The following is an example of preparation 1.
Preparation example 1
In this application, the cationically modified carbon particles are prepared according to the following method:
(1) Zinc nitrate is dissolved in deionized water to obtain cation modified liquid with zinc ion concentration of 2mol/L for standby; drying rice hulls, and then cutting the dried rice hulls to an average particle size of 600 mu m to obtain rice hull particles for later use; mixing rice hull particles and cationic modified liquid according to a 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 rice hull particle mixture; in the step, the mixing liquid is ethanol water solution with the mass fraction of 30% of ethanol, 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 to 600 ℃ from room temperature at a heating rate of 5 ℃/min, calcining the rice hull particle mixture to constant weight at 600 ℃, washing the calcined product by using deionized water, drying, and crushing the calcined product to an average particle size of 800 mu m to obtain the cation modified carbon particles.
As shown in Table 1, preparation examples 1-5 differ in the amount of raw materials used to blend the rice hull particle blend.
TABLE 1
Preparation example 6
The difference between this preparation example and preparation example 3 is that in the step (1) of preparing the cation modified carbon particles, after the rice hull particle dispersion liquid is obtained, cellulase with the enzyme activity of 100000U/g is further added into the rice hull particle dispersion liquid, and the weight ratio of cellulase to rice hull particle is 1:100.
as shown in Table 2, preparation examples 6-10 differ in the weight ratio of cellulase to rice hull particles.
TABLE 2
PREPARATION EXAMPLE 11
The difference between this preparation example and preparation example 8 is that only calcium nitrate was dissolved in deionized water when preparing the cation-modified liquid, to obtain a cation-modified liquid having a calcium ion concentration of 2 mol/L.
Preparation example 12
The difference between this preparation example and preparation example 11 is that zinc nitrate and calcium nitrate are dissolved together in deionized water when preparing the cation modified liquid, so as to obtain a cation modified liquid with zinc ion concentration and calcium ion concentration of 1 mol/L.
Preparation example 13
This preparation differs from preparation 12 in that the xanthan gum is replaced by the same weight of gelatin.
PREPARATION EXAMPLE 14
The difference between this preparation example and preparation example 13 is that the mixture was an aqueous glycerol solution having a glycerol mass fraction of 30%.
Preparation example 15
This preparation differs from preparation 14 in that in step (3) of preparing the cation-modified carbon particles, phosphoric acid having a concentration of 0.1mol/L is selected for washing the calcined product.
PREPARATION EXAMPLE 16
The difference between this preparation example and preparation example 15 is that in the step (3) of preparing the cation-modified carbon particles, the calcined product is washed with hydrofluoric acid having a concentration of 0.1mol/L
Preparation example 17
This preparation differs from preparation 16 in that ammonium polyphosphate was used in place of red phosphorus in a molar ratio of phosphorus of 1:1, the average degree of polymerization of the ammonium polyphosphate being 45.
PREPARATION EXAMPLE 18
This preparation differs from preparation 17 in that the same weight of sodium silicate was used instead of sodium dodecyl sulfate.
Preparation example 19
This preparation differs from preparation 17 in that the stabilizer comprises 3kg sodium lauryl sulfate and 3kg sodium silicate.
Examples
The raw materials used in the examples of this application are all commercially available, with nitrocotton wastewater being supplied by Hemiq water and cellulose-rich limited.
Examples 1 to 5
The following description will take example 1 as an example.
Example 1
In example 1, the impurity removal process of the chemical auxiliary agent comprises the following steps:
(1) Soaking the cation modified carbon particles in preparation example 1 for 2 hours by using 1mol/L nitric acid according to a solid-to-liquid ratio of 1:5, then fishing out the cation modified carbon particles, and drying the cation modified carbon particles at 70 ℃ for later use;
(2) Uniformly mixing the cationic 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 for 24 hours at room temperature; 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-impurity chemical auxiliary agent.
As shown in Table 3, examples 1-19 differ primarily in the preparation of cationically modified carbon particles.
TABLE 3 Table 3
Example 20
Zxfoom 19 are different in that, 19, respectively is characterized in that, the mass fraction of sulfate ions in the diluent is 2.6%, the mass fraction of nitrate ions was 8%.
Example 21
The difference between this example and example 20 is that in step (2) of the impurity removal process, iron powder and hydrogen peroxide are added to the mixed solution after the mixed solution is obtained, the average particle diameter 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 were different in terms of the molar ratio of hydrogen peroxide to iron powder.
TABLE 4 Table 4
Comparative example
Comparative example 1
This comparative example differs from example 3 in that the same weight of activated carbon was used instead of the cationically modified carbon particles.
Comparative example 2
This comparative example differs from example 3 in that the cationically modified carbon particles are immersed in deionized water in step (1) of the impurity removal process.
Performance detection test method
For examples 1-20 and comparative examples 1-3, the initial sulfate ion mass fraction (w 0 ) And the mass fraction (w) of sulfate ions in the low-impurity chemical auxiliary agent obtained after impurity removal 1 ) The sulfate ion removal rate was then calculated according to the following formula.
The results of the calculation of sulfate ion removal rate are shown in Table 5.
TABLE 5
For examples 20-25, the COD value (m) of the crude chemical auxiliary was measured using a WWH-CODcr industrial analytical COD detector provided by WWW-Wash instruments, inc 0 ) And low-hybrid auxiliary agent (m) 1 ) The cod removal rate is then calculated as follows.
The calculation result of the cod removal rate is shown in Table 6.
TABLE 6
| Sample of | 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 |
As can be seen from the combination of examples 1 to 5 and comparative example 1 and table 5, the sulfate ion removal rates measured in examples 1 to 5 are higher than those in comparative example 1, which means 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 sulfate ion removal rates measured in examples 1-5 are all above 70%, which shows that most of sulfate ions in the crude chemical auxiliary agent are transferred into the cation modified carbon particles after the cation modified carbon particles are treated, so that the sulfate ion content 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 in the sulfuric acid method on the market.
Zxfoom 3 2 zxfoom 5 , and combine Table 5 it can be seen that the light source is, description of the use of nitric acid for acidizing cationically modified carbon particles the adsorption effect of the cation modified carbon particles on sulfate ions is improved.
As can be seen from the combination of the example 3 and the examples 6-10 and the table 5, the sulfate ion removal rates measured in the examples 6-10 are higher than that in the example 3, which indicates that the cellulase can catalyze the decomposition of cellulose, thereby reducing the density of rice hull particles, making the prepared cation modified carbon particles more porous and more porous, and being beneficial to improving the adsorption effect of the cation modified carbon particles on sulfate ions.
As can be seen from the combination of examples 8, 11-12 and Table 5, example 11 shows a lower sulfate ion removal rate than example 8, indicating that zinc ions have better adsorption performance than calcium ions. In example 12, when the calcium ions and the zinc ions are used for treating the rice hull particles together, the calcium ions can reduce the adsorption of lignin in the rice hull particles to the cellulase, so that the effect of the cellulase on reducing the density of the rice hull particles is improved, the absorption of the zinc ions by the rice hull particles is promoted, and the adsorption performance of the cation modified carbon particles is improved.
Zxfoom 13, example 12 in combination with table 5 it can be seen that, example 12 incorporation as can be seen in table 5 of the drawings, the gelatin is not easy to block the air holes formed by the rice hull particle mixture at the initial stage of calcination, the replacement of xanthan gum with gelatin thus helps to enhance the adsorption effect of the cationically modified carbon particles.
Zxfoom 13, example 14 in combination with table 5 it can be seen that, example 14 and incorporation as can be seen in table 5 of the drawings, the glycerol aqueous solution is described as extending the time for which the rice hull particle mixture remains wet, the possibility of hardening of rice hull particle mixture is reduced, and the adsorption performance of the cation modified carbon particles is improved.
As can be seen from the combination of examples 14, 15-16 and Table 5, the sulfate ion removal rates measured in example 15 and example 16 are higher than those in example 14, indicating that both phosphoric acid and hydrofluoric acid can increase the number of polar functional groups on the surface of the cationically modified carbon particles, thereby activating the cationically modified carbon particles and improving the adsorption performance of the cationically modified carbon particles. The sulfate ion removal rate measured in example 16 was higher than that in example 15, indicating that hydrofluoric acid increased the porosity of the cationically modified carbon particles by etching the silica, further improving the adsorption performance of the cationically modified carbon particles.
As can be seen from the combination of example 16 and example 17 and the combination of table 5, the sulfate ion removal rate measured in example 17 is higher than that in example 16, which demonstrates that ammonia gas generated by decomposition of ammonium polyphosphate can form air holes in the rice hull particle mixture during diffusion, thus contributing to the improvement of the adsorption performance of the cation-modified carbon particles.
As can be seen from a combination of examples 17 and examples 18-19 and Table 5, the sulfate ion removal rates measured in examples 17 and 18 are close, indicating that sodium silicate and sodium dodecyl sulfate have close stabilizing effects when the weights are the same. The sulfate ion removal rate measured in example 19 was higher than that measured in examples 17 and 18, indicating that the effect of sodium silicate and sodium dodecyl sulfate when used together was superior to that when used alone.
As can be seen by combining example 20 and example 3 with table 5, the sulfate ion removal rate 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 a combination of examples 20, examples 21-25 and Table 6, the cationic modified carbon particles in example 20 adsorb organic residues, thus reducing the cod value of the acidic nitrocotton wastewater dilution. In examples 21 to 25, ferrous nitrate and hydrogen peroxide which can be generated by the reaction of the elemental iron and the dilute nitric acid can undergo a Fenton reaction, and hydroxyl radicals generated by the Fenton reaction oxidize organic residues, so that the organic residues are cleaned, the cod value is reduced, and the purity of the acidic nitrocotton wastewater diluent is improved.
The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.
Claims (8)
1. The impurity removal process of the chemical auxiliary agent is characterized by comprising the following steps of:
(1) Soaking the cation modified carbon particles by using nitric acid, and then drying the cation modified carbon particles for standby; 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 prepared in the step (1) to obtain a mixed solution, and standing the mixed solution at room temperature; the crude chemical auxiliary agent is dilute solution of acidic 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%; in the step, after the mixed solution is obtained, iron powder and hydrogen peroxide are also added into the mixed solution, wherein the molar ratio of the hydrogen peroxide to the iron powder is (2.2-2.4): 1, a step of;
(3) Concentrating and crystallizing the mixed solution after standing, and filtering to remove filter residues to obtain the low-impurity chemical auxiliary agent;
the cation modified carbon particles are prepared according to the following method:
(I) Drying rice hulls, then cutting to obtain rice hull particles, mixing the rice hull particles with a cation modified liquid, and uniformly stirring to obtain rice hull particle dispersion liquid, wherein the cation modified liquid is a salt solution containing divalent metal cations; in the step, after rice hull particle dispersion liquid is obtained, cellulase is further added into the rice hull particle dispersion liquid, and the weight ratio of the cellulase to the rice hull particles is 1 according to the enzyme activity of the cellulase of 100000U/g: (100-120);
(II) removing water in the rice hull particle dispersion liquid to obtain cation modified rice hull particles, and mixing, heating and uniformly stirring 60-80 parts of cation modified rice hull particles, 30-50 parts of a mixing liquid, 8-12 parts of an organic binder, 6-8 parts of a flame retardant and 4-8 parts of a stabilizer according to parts by weight to obtain a rice hull particle mixture; the liquid component with the highest content in the mixing liquid is water;
(III) calcining the rice hull particle mixture to constant weight at a temperature higher than the ignition point of the rice hulls, and then washing and drying the calcined product and crushing to obtain the cation modified carbon particles.
2. The process for removing impurities from a chemical auxiliary according to claim 1, wherein the divalent metal cation is at least one of zinc ion and calcium ion.
3. The process for removing impurities from a chemical auxiliary according to claim 1, wherein the organic binder is xanthan gum or gelatin.
4. The process for removing impurities from a chemical auxiliary according to claim 1, wherein the mixing solution is an aqueous glycerol solution or an aqueous ethanol solution.
5. The process for removing impurities from a chemical auxiliary according to claim 1, wherein in the step (III) of preparing the cation-modified carbon particles, phosphoric acid or hydrofluoric acid is selected to wash the calcined product.
6. The process for removing impurities from a chemical auxiliary according to claim 1, wherein the flame retardant is ammonium polyphosphate or red phosphorus.
7. The process for removing impurities from a chemical auxiliary according to claim 1, wherein the stabilizer is at least one selected from sodium silicate and sodium dodecyl sulfate.
8. The process for removing impurities from chemical auxiliary according to claim 1, wherein the crude chemical auxiliary is a diluted solution of acidic nitrocotton wastewater, and the mass fraction of nitric acid in the diluted solution of acidic nitrocotton wastewater is 5-10%.
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