Regenerated anion resin for purifying water and preparation method thereof

Abstract

The invention discloses regenerated anion resin for water purification and a preparation method thereof, and belongs to the technical field of resin regeneration, and the method specifically comprises the steps of water washing, calcium hypochlorite oxidation, liquid caustic soda washing, pH adjustment, cleaning and packaging. Calcium hypochlorite is used for oxidizing macromolecular organic impurities, sodium hydroxide is used for removing micromolecular organic matters, and hydrochloric acid is used for adjusting the pH value. Compared with the prior art, the regenerated anion resin provided by the invention has excellent performance in the aspects of average pore size, specific surface area and organic matter adsorption rate, and is suitable for the field of water treatment, especially for application scenarios requiring efficient regenerated anion resin to improve water quality.

Description

Technical Field

[0001] The invention relates to the technical field of resin regeneration, in particular to a regenerated anionic resin for water purification and a preparation method thereof. Background Art

[0002] In the field of water treatment, anion exchange resins are widely used to remove anionic impurities in water, such as sulfate ions (SO4 2- ), chloride ion (Cl - ) to improve water quality. However, as the number of uses increases, anion exchange resins will gradually adsorb a large amount of organic impurities, such as humic acid, fulvic acid, low molecular weight organic carboxylic acids, polybasic organic carboxylic acids and other soluble organic matter. These organics are adsorbed on strong base anion resins through van der Waals forces and chemical affinity, with low elution rates, which ultimately affect the working exchange capacity of the resin and the quality of the effluent. In addition, some heavy metal ions may also be adsorbed in the waste anion resin, further reducing the treatment effect of the resin.

[0003] Existing resin regeneration technologies mainly rely on physical and chemical methods, such as thermal regeneration, acid-base regeneration, etc. However, these methods have some limitations. For example, thermal regeneration requires high temperature treatment, high energy consumption, and may cause damage to the resin structure; although acid-base regeneration can remove some organic matter, it is not effective in removing large molecular organic impurities, and the cost of wastewater treatment is high. Therefore, the development of an efficient and environmentally friendly method for preparing regenerated anionic resin is of great significance for improving the regeneration efficiency of the resin and reducing the treatment cost.

[0004] Chinese invention patent CN110975851A discloses a method for desorption and regeneration of resin adsorbed with organic matter, including the step of desorption and regeneration of resin adsorbed with organic matter by using a premixed nitrogen and water vapor mixed gas; the water vapor in the mixed gas forms an azeotrope with the organic matter adsorbed on the resin, so that the organic matter is discharged from the resin tower with the mixed gas. Furthermore, the desorbed nitrogen and the gas containing organic matter are dehydrated by molecular sieves together, wherein water is absorbed by the molecular sieve, and the nitrogen and organic matter are discharged separately and then condensed to recover the organic matter, and the nitrogen can be recovered for continued use. Compared with the desorption of full water vapor at the same pressure, the method of desorption and regeneration of resin by using a mixed gas of nitrogen and water vapor of the invention can achieve a level of desorption effect equivalent to that of full water vapor by using a smaller amount of steam in the invention, and can effectively reduce the amount of wastewater generated after desorption, and reduce the cost of wastewater treatment. However, the resin desorption and regeneration method of the invention still has room for improvement in terms of average pore size, specific surface area and adsorption rate of organic matter. Summary of the invention

[0005] In order to address the deficiencies in the prior art, the present invention aims to provide a regenerated anion resin for water purification and a preparation method thereof. Through a series of optimized chemical treatment steps, the macromolecular and small molecular organic impurities adsorbed inside the waste anion resin are effectively removed, while the pore structure of the waste anion resin is optimized, the specific surface area is increased, and the adsorption capacity for organic matter is improved, thereby achieving efficient regeneration of the waste anion resin and improving its application performance in the field of water purification.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] A method for preparing a regenerated anionic resin for water purification is as follows:

[0008] Step 1, water washing: the waste anion resin that has passed the quality inspection is vacuum pumped into a regeneration kettle pre-installed with a filter screen, and washed with water in reverse flow;

[0009] Step 2, calcium hypochlorite oxidation: After the waste anion resin is washed, in order to effectively remove a small amount of macromolecular organic impurities adsorbed inside it, a 0.1-0.3wt% calcium hypochlorite aqueous solution is pumped into the regeneration kettle, and then the steam jacket is opened, the temperature is controlled at 35-45°C, and the immersion treatment is carried out under normal pressure. The immersion time is 5-6 hours. During the immersion process, the stirring device needs to be turned on every hour for continuous stirring for 10-15 minutes to ensure that the material can fully react;

[0010] Step 3, liquid alkali washing: After the calcium hypochlorite oxidation treatment is completed, in order to further remove small molecular organic matter and exchange part of the sulfate ions and chloride ions adsorbed inside the waste anion resin, a pre-prepared 4-6wt% sodium hydroxide aqueous solution is pumped into the regeneration kettle together with water; stirring treatment is carried out under normal temperature and pressure conditions, and the stirring time is 1-3 hours to ensure that the material can be fully washed;

[0011] Step 4, adjusting pH: After the liquid alkali washing is completed, in order to adjust the pH value of the solution to an appropriate range, the pre-prepared 4-6wt% hydrochloric acid is pumped into the regeneration kettle together with water, and stirred at normal temperature and pressure for 0.5-2 hours until the pH value of the solution drops to 4-5, and the neutralization reaction is completed. During the feeding process of 4-6wt% hydrochloric acid, no hydrochloric acid mist is generated;

[0012] Step 5, washing: After the pH adjustment is completed, water is used for countercurrent washing again to remove a small amount of broken resin that may be produced during the oxidation process. The entire water washing process lasts for 0.3 to 0.8 hours;

[0013] Step 6, packaging: After the above cleaning steps, the regenerated anion resin is vacuum pumped into the packaging tank, and then the material is discharged and packaged. The final finished product is sent to the finished product warehouse for sale, completing the entire preparation process of the regenerated anion resin.

[0014] Preferably, the preparation method of the regenerated anion resin for water purification is as follows:

[0015] Step 1, water washing: the waste anion resin that has passed the quality inspection is vacuum pumped into a regeneration kettle pre-installed with a filter screen, and washed with water in reverse flow;

[0016] Step 2, calcium hypochlorite oxidation: After the waste anion resin is washed with water, in order to effectively remove a small amount of macromolecular organic impurities adsorbed inside it, a functional agent is pumped into the regeneration kettle, and a stirring and soaking treatment is carried out under normal pressure conditions. The stirring and soaking time is 3 to 5 hours, and then the functional agent is removed, and a 0.1 to 0.3 wt% calcium hypochlorite aqueous solution is pumped into the regeneration kettle. Subsequently, the steam jacket is opened, the temperature is controlled at 35 to 45° C., and the soaking treatment is carried out under normal pressure conditions. The soaking time is 5 to 6 hours. During the soaking process, the stirring device needs to be turned on every hour to continuously stir for 10 to 15 minutes to ensure that the material can fully react;

[0017] Step 3, liquid alkali washing: After the calcium hypochlorite oxidation treatment is completed, in order to further remove small molecular organic matter and exchange part of the sulfate ions and chloride ions adsorbed inside the waste anion resin, a pre-prepared 4-6wt% sodium hydroxide aqueous solution is pumped into the regeneration kettle together with water; stirring treatment is carried out under normal temperature and pressure conditions, and the stirring time is 1-3 hours to ensure that the material can be fully washed;

[0018] Step 4, adjusting pH: After the liquid alkali washing is completed, in order to adjust the pH value of the solution to an appropriate range, the pre-prepared 4-6wt% hydrochloric acid is pumped into the regeneration kettle together with water, and stirred at normal temperature and pressure for 0.5-2 hours until the pH value of the solution drops to 4-5, and the neutralization reaction is completed. During the feeding process of 4-6wt% hydrochloric acid, no hydrochloric acid mist is generated;

[0019] Step 5, washing: After the pH adjustment is completed, water is used for countercurrent washing again to remove a small amount of broken resin that may be produced during the oxidation process. The entire water washing process lasts for 0.3 to 0.8 hours;

[0020] Step 6, packaging: After the above cleaning steps, the regenerated anion resin is vacuum pumped into the packaging tank, and then the material is discharged and packaged. The final finished product is sent to the finished product warehouse for sale, completing the entire preparation process of the regenerated anion resin.

[0021] The countercurrent washing in step 1 is performed twice. The water from the first washing is used for the second washing after precipitation to remove broken resin impurities. The whole washing process lasts for 0.5 to 2 hours.

[0022] The mass ratio of the waste anionic resin to the functional agent is 1:4-6.

[0023] The mass ratio of the waste anionic resin to the calcium hypochlorite aqueous solution is 1:4-6.

[0024] The mass ratio of the waste anion resin, 4-6wt% sodium hydroxide aqueous solution and water is 1:2-4:2-4.

[0025] The mass ratio of the waste anion resin, 4-6wt% hydrochloric acid and water is 1:2-4:2-4.

[0026] The preparation method of the functional agent is as follows:

[0027] S1, adding sodium pyrophosphate and N-acetylcysteine ​​into water, stirring evenly, to obtain a pretreated product;

[0028] S2, adding carboxylesterase and sorbitol to the pre-treated material, stirring and mixing, and standing at low temperature, normal pressure, and light-proof conditions to obtain a post-treatment solution;

[0029] S3. Add post-treatment liquid, calcium hypochlorite and trans-1,2-cyclohexanediaminetetraacetic acid into water, stir and mix, and then let stand at room temperature, pressure and light-proof conditions to obtain a functional agent.

[0030] Further preferably, the preparation method of the functional agent is as follows, in parts by weight:

[0031] S1, adding 500-700 parts of sodium pyrophosphate and 0.05-0.2 parts of N-acetylcysteine ​​to 1800-2200 parts of water, stirring them thoroughly to mix them evenly, to obtain a pretreated product;

[0032] S2, add 40-60 parts of carboxylesterase and 400-600 parts of sorbitol to the pretreated material prepared in step S1, stir and mix again, then place at a temperature of 2-8° C., avoid light at normal pressure and stand for 4-8 days to obtain a post-treatment solution;

[0033] S3. Add 300 to 500 parts of the post-treatment liquid prepared in step S2, 8 to 12 parts of calcium hypochlorite and 18 to 22 parts of trans-1,2-cyclohexanediaminetetraacetic acid into 8000 to 12000 parts of water, stir to fully mix, and let the mixed solution stand for 1 to 3 days at room temperature and pressure to avoid light to obtain a functional agent.

[0034] In the present invention, the functions of each substance are as follows:

[0035] The spent anion resin is the main treatment object and is regenerated through a series of chemical treatment steps to restore its adsorption performance for water purification.

[0036] Calcium hypochlorite is used as an oxidant to oxidize the macromolecular organic impurities adsorbed inside the waste anion resin, such as humic acid, fulvic acid, low molecular organic carboxylic acid, polybasic organic carboxylic acid and other soluble organic matter. Calcium hypochlorite can destroy the structure of these organic matter and decompose them into small molecular substances, which are easier to elute from the resin surface and improve the regeneration effect of the resin.

[0037] The sodium hydroxide aqueous solution is used as an alkaline detergent in the liquid alkali washing step to further remove the small molecular organic matter adsorbed inside the waste anionic resin and exchange some sulfate ions and chloride ions adsorbed inside the resin to improve the purity and performance of the resin.

[0038] Hydrochloric acid is used to adjust the pH value of the solution to an appropriate range (4~5), neutralize the alkaline environment after liquid alkali washing, ensure that the resin is subsequently treated under neutral or weakly acidic conditions, and improve the stability and adsorption performance of the resin.

[0039] Sodium pyrophosphate is used as a pretreatment agent in the preparation of functional agents to provide a stable chemical environment, promote the mixing and reaction of other ingredients, and enhance the performance of the functional agent.

[0040] N-acetylcysteine ​​acts as a reducing agent and stabilizer, providing reducing power, protecting other ingredients from oxidation, and increasing the stability and water solubility of the functional agent in aqueous solution.

[0041] As an enzyme catalyst, carboxylesterase can effectively hydrolyze ester-containing compounds such as organophosphorus pesticides, and decompose the ester bonds in humic acid, fulvic acid, low-molecular organic carboxylic acids, polybasic organic carboxylic acids and other soluble organic matter adsorbed inside the waste anion resin, thereby removing these organic impurities and improving the regeneration effect of the resin.

[0042] Sorbitol acts as a protective agent and stabilizer, providing a mild chemical environment to protect the activity of the enzyme and prevent the enzyme from being inactivated during the treatment process, while increasing the stability and water solubility of the functional agent.

[0043] As a chelating agent, trans-1,2-cyclohexanediaminetetraacetic acid can form a highly stable water-soluble complex with metal ions, reduce the negative impact of metal ions on resin performance, and improve the regeneration effect of the resin and the adsorption rate of organic matter.

[0044] These substances work synergistically in the present invention, through a series of optimized chemical treatment steps, to effectively remove organic impurities adsorbed inside the waste anion resin, optimize the pore structure of the resin, increase the specific surface area, and improve the adsorption capacity for organic matter, thereby achieving efficient regeneration of the waste anion resin and improving its application performance in the water purification field.

[0045] Compared with the prior art, it has the following beneficial effects:

[0046] 1) The present invention effectively removes macromolecular and small molecular organic impurities adsorbed inside the waste anion resin through optimized chemical treatment steps, including calcium hypochlorite oxidation, liquid alkali washing and pH adjustment, and significantly improves the purity and performance of the regenerated anion resin. The use of specific functional agents further enhances the ability to decompose and remove organic impurities, optimizes the pore structure of the waste anion resin, increases the specific surface area, and thus improves the adsorption capacity of organic matter.

[0047] 2) The present invention adopts calcium hypochlorite oxidation treatment to destroy the structure of organic matter adsorbed inside the waste anionic resin, decomposing it into small molecules, which are easier to elute from the resin surface, thereby reducing the accumulation of organic matter inside the resin.

[0048] 3) The present invention adopts mild chemical treatment conditions, such as stirring and soaking at normal temperature and pressure, which reduces energy consumption and equipment requirements, and reduces treatment costs. Through optimized treatment steps, the generation of wastewater and waste residue is reduced, the negative impact on the environment is reduced, and the safety and sustainability of the treatment process are improved. DETAILED DESCRIPTION

[0049] Main sources of substances:

[0050] Waste anionic resins come from water purification resins used in thermal power plants and industrial enterprises that the company serves (waste resins that have been regenerated more than 50 times by the above-mentioned enterprises), and do not involve waste ion exchange resins generated by hydrometallurgy, surface treatment, and heavy metal, antibiotic extraction and separation processes in the pharmaceutical industry, and waste ion exchange resins generated by industrial wastewater treatment processes.

[0051] Carboxylesterase, specific activity ≥150 units / mg protein (biuret), molecular weight: 168 kDa, storage temperature: 2-8°C, purchased from Merck.

[0052] Proteinase K, specific activity ≥ 2 units / mg protein, storage temperature: 2-8°C, purchased from Merck.

[0053] The remaining raw materials in the examples and comparative examples of the present invention are all commercially available products.

[0054] The design idea of ​​the present invention is to effectively remove the macromolecular and small molecular organic impurities adsorbed inside the waste anion resin through a series of optimized chemical treatment steps, including water washing, calcium hypochlorite oxidation, liquid alkali washing, pH adjustment, cleaning and packaging, combined with a specific functional agent preparation method, while optimizing the pore structure of the waste anion resin, increasing the specific surface area, and improving the adsorption capacity of organic matter, thereby achieving efficient regeneration of the waste anion resin and improving its application performance in the field of water purification.

[0055] Example 1

[0056] A method for preparing a regenerated anionic resin for water purification is as follows:

[0057] Step 1, water washing: the waste anion resin that has passed the quality inspection is vacuum pumped into a regeneration kettle pre-installed with a filter, and is washed in countercurrent with water, specifically twice. The water from the first water washing is precipitated to remove broken resin impurities and then reused for the second water washing. The whole water washing process lasts for 1 hour;

[0058] Step 2, calcium hypochlorite oxidation: After the waste anion resin is washed with water, in order to effectively remove a small amount of macromolecular organic impurities adsorbed inside it, a 0.2wt% calcium hypochlorite aqueous solution is pumped into the regeneration kettle, the mass ratio of the waste anion resin to the calcium hypochlorite aqueous solution is 1:5, then the steam jacket is opened, the temperature is controlled at 40°C, and the immersion treatment is carried out under normal pressure for 5 hours. During the immersion process, the stirring device needs to be turned on for 12 minutes every hour to ensure that the material can react fully;

[0059] Step 3, liquid alkali washing: After the calcium hypochlorite oxidation treatment is completed, in order to further remove small molecular organic matter and exchange part of the sulfate ions (SO4 2- ), chloride ion (Cl - ), pumping the pre-prepared 5wt% sodium hydroxide aqueous solution and water into the regeneration kettle; the mass ratio of the waste anion resin, 5wt% sodium hydroxide aqueous solution and water is 1:3:3, and stirring is carried out under normal temperature and pressure conditions for 2 hours to ensure that the material can be fully washed;

[0060] Step 4, adjusting pH: After the liquid alkali washing is completed, in order to adjust the pH value of the solution to an appropriate range, the pre-prepared 5wt% hydrochloric acid and water are pumped into the regeneration kettle together, the mass ratio of the waste anion resin, 5wt% hydrochloric acid and water is 1:3:3, and the stirring treatment is carried out at normal temperature and pressure. The stirring time is 1 hour until the pH value of the solution drops to 4.5 and the neutralization reaction is completed. During the feeding process of 5wt% hydrochloric acid, no hydrochloric acid mist is generated;

[0061] Step 5, washing: After the pH adjustment is completed, water is used for countercurrent washing again to remove a small amount of broken resin that may be generated during the oxidation process. The entire water washing process lasts for 0.5 hours;

[0062] Step 6, packaging: After the above cleaning steps, the regenerated anion resin is vacuum pumped into the packaging tank, and then the material is discharged and packaged. The final finished product is sent to the finished product warehouse for sale, completing the entire preparation process of the regenerated anion resin.

[0063] Example 2

[0064] A method for preparing a regenerated anionic resin for water purification is as follows:

[0065] Step 1, water washing: the waste anion resin that has passed the quality inspection is vacuum pumped into a regeneration kettle pre-installed with a filter, and is washed in countercurrent with water, specifically twice. The water from the first water washing is precipitated to remove broken resin impurities and then reused for the second water washing. The whole water washing process lasts for 1 hour;

[0066] Step 2, calcium hypochlorite oxidation: after the waste anion resin is washed with water, in order to effectively remove a small amount of macromolecular organic impurities adsorbed inside it, a functional agent is pumped into the regeneration kettle, the mass ratio of the waste anion resin to the functional agent is 1:5, and stirring and soaking treatment is carried out under normal pressure conditions for 48 hours, and then the functional agent is removed, and a 0.2wt% calcium hypochlorite aqueous solution is pumped into the regeneration kettle, the mass ratio of the waste anion resin to the calcium hypochlorite aqueous solution is 1:5, then, the steam jacket is opened, the temperature is controlled at 40°C, and the soaking treatment is carried out under normal pressure conditions for 5 hours. During the soaking process, the stirring device needs to be turned on for 12 minutes every hour to ensure that the material can react fully;

[0067] Step 3, liquid alkali washing: After the calcium hypochlorite oxidation treatment is completed, in order to further remove small molecular organic matter and exchange part of the sulfate ions (SO4 2- ), chloride ion (Cl - ), pumping the pre-prepared 5wt% sodium hydroxide aqueous solution and water into the regeneration kettle; the mass ratio of the waste anion resin, 5wt% sodium hydroxide aqueous solution and water is 1:3:3, and stirring is carried out under normal temperature and pressure conditions for 2 hours to ensure that the material can be fully washed;

[0068] Step 4, adjusting pH: After the liquid alkali washing is completed, in order to adjust the pH value of the solution to an appropriate range, the pre-prepared 5wt% hydrochloric acid and water are pumped into the regeneration kettle together, the mass ratio of the waste anion resin, 5wt% hydrochloric acid and water is 1:3:3, and the stirring treatment is carried out at normal temperature and pressure. The stirring time is 1 hour until the pH value of the solution drops to 4.5 and the neutralization reaction is completed. During the feeding process of 5wt% hydrochloric acid, no hydrochloric acid mist is generated;

[0069] Step 5, washing: After the pH adjustment is completed, water is used for countercurrent washing again to remove a small amount of broken resin that may be generated during the oxidation process. The entire water washing process lasts for 0.5 hours;

[0070] Step 6, packaging: After the above cleaning steps, the regenerated anion resin is vacuum pumped into the packaging tank, and then the material is discharged and packaged. The final finished product is sent to the finished product warehouse for sale, completing the entire preparation process of the regenerated anion resin.

[0071] The preparation method of the functional agent is as follows:

[0072] S1, adding 600g of sodium pyrophosphate and 100mg of N-acetylcysteine ​​to 2000g of water, stirring them thoroughly to mix them evenly, to obtain a pretreated product;

[0073] S2, adding 50g of carboxylesterase and 500g of sorbitol to the pretreated material prepared in step S1, stirring and mixing again, and then placing at a temperature of 3°C, avoiding light at normal pressure and standing for 6 days to obtain a post-treatment solution;

[0074] S3. Add 400 g of the post-treatment liquid prepared in step S2, 10 g of calcium hypochlorite and 20 g of trans-1,2-cyclohexanediaminetetraacetic acid into 10 kg of water, stir to mix them thoroughly, and let the mixed solution stand for 2 days at room temperature and pressure, avoiding light, to obtain a functional agent.

[0075] Example 3

[0076] The method for preparing a regenerated anionic resin for water purification is substantially the same as that of Example 2, the only difference being the method for preparing the functional agent.

[0077] The preparation method of the functional agent is as follows:

[0078] S1, adding 600g of sodium pyrophosphate and 100mg of reduced glutathione to 2000g of water, stirring them thoroughly to mix them evenly, to obtain a pretreated product;

[0079] S2, adding 50g of carboxylesterase and 500g of sorbitol to the pretreated material prepared in step S1, stirring and mixing again, and then placing at a temperature of 3°C, avoiding light at normal pressure and standing for 6 days to obtain a post-treatment solution;

[0080] S3. Add 400 g of the post-treatment liquid prepared in step S2, 10 g of calcium hypochlorite and 20 g of trans-1,2-cyclohexanediaminetetraacetic acid into 10 kg of water, stir to mix them thoroughly, and let the mixed solution stand for 2 days at room temperature and pressure, avoiding light, to obtain a functional agent.

[0081] Example 4

[0082] The method for preparing a regenerated anionic resin for water purification is substantially the same as that of Example 2, the only difference being the method for preparing the functional agent.

[0083] The preparation method of the functional agent is as follows:

[0084] S1, adding 600g of sodium pyrophosphate and 100mg of N-acetylcysteine ​​to 2000g of water, stirring them thoroughly to mix them evenly, to obtain a pretreated product;

[0085] S2. Add 50 g of proteinase K and 500 g of sorbitol to the pretreated product prepared in step S1, stir and mix again, and then place at 3° C. and avoid light at normal pressure for 6 days to obtain a post-treated solution;

[0086] S3. Add 400 g of the post-treatment liquid prepared in step S2, 10 g of calcium hypochlorite and 20 g of trans-1,2-cyclohexanediaminetetraacetic acid into 10 kg of water, stir to mix them thoroughly, and let the mixed solution stand for 2 days at room temperature and pressure, avoiding light, to obtain a functional agent.

[0087] Example 5

[0088] The method for preparing a regenerated anionic resin for water purification is substantially the same as that of Example 2, the only difference being the method for preparing the functional agent.

[0089] The preparation method of the functional agent is as follows:

[0090] S1, adding 600g of sodium pyrophosphate and 100mg of N-acetylcysteine ​​to 2000g of water, stirring them thoroughly to mix them evenly, to obtain a pretreated product;

[0091] S2, adding 50g of carboxylesterase and 500g of sorbitol to the pretreated material prepared in step S1, stirring and mixing again, and then placing at a temperature of 3°C, avoiding light at normal pressure and standing for 6 days to obtain a post-treatment solution;

[0092] S3. Add 400 g of the post-treatment solution prepared in step S2, 10 g of calcium hypochlorite and 20 g of triethylenetetraaminehexaacetic acid into 10 kg of water, stir to mix them thoroughly, and let the mixed solution stand for 2 days at room temperature and pressure, avoiding light, to obtain a functional agent.

[0093] Comparative Example 1

[0094] The method for preparing a regenerated anionic resin for water purification is substantially the same as that of Example 2, the only difference being the method for preparing the functional agent.

[0095] The preparation method of the functional agent is as follows:

[0096] S1, adding 600g of sodium pyrophosphate and 100mg of N-acetylcysteine ​​to 2000g of water, stirring them thoroughly to mix them evenly, to obtain a pretreated product;

[0097] S2, adding 50g of carboxylesterase and 500g of sorbitol to the pretreated material prepared in step S1, stirring and mixing again, and then placing at a temperature of 3°C, avoiding light at normal pressure and standing for 6 days to obtain a post-treatment solution;

[0098] S3, adding 400g of the post-treatment liquid prepared in step S2, 10g of sodium persulfate and 20g of trans-1,2-cyclohexanediaminetetraacetic acid into 10kg of water, stirring to fully mix, and leaving the mixed solution at room temperature and pressure to stand for 2 days without exposure to light to obtain a functional agent.

[0099] Comparative Example 2

[0100] The method for preparing a regenerated anionic resin for water purification is substantially the same as that of Example 2, the only difference being the method for preparing the functional agent.

[0101] The preparation method of the functional agent is as follows:

[0102] S1, adding 600g of sodium pyrophosphate and 100mg of N-acetylcysteine ​​to 2000g of water, stirring them thoroughly to mix them evenly, to obtain a pretreated product;

[0103] S2, adding 50g of carboxylesterase and 500g of sorbitol to the pretreated material prepared in step S1, stirring and mixing again, and then placing at a temperature of 3°C, avoiding light at normal pressure and standing for 6 days to obtain a post-treatment solution;

[0104] S3, add 400g of the post-treatment liquid prepared in step S2, 10g of calcium hypochlorite and 20g of ethylenediaminetetraacetic acid into 10kg of water, stir to mix them thoroughly, and let the mixed solution stand for 2 days at room temperature and pressure, avoiding light, to obtain a functional agent.

[0105] Test Example 1

[0106] Average pore size and specific surface area

[0107] The regenerated anionic resin prepared by the present invention is measured using a BET pore size specific surface area analyzer, and specific test data are shown in Table 1.

[0108] Table 1 Experimental protocol Average pore size (nm) <![CDATA[Specific surface area (m 2 / g)]]> Example 1 20.4 1264 Example 2 26.4 1462 Example 3 24.8 1396 Example 4 24.9 1399 Example 5 23.7 1368 Comparative Example 1 22.6 1337 Comparative Example 2 22.5 1329

[0109] Test Example 2

[0110] Organic matter adsorption rate test

[0111] The molecular weight distribution of organic matter in water is determined by ultrafiltration. The regenerated anion resin prepared by the present invention is installed in an adsorption column, and Shanghai tap water is passed through. The molecular weight distribution of organic matter in the effluent of the adsorption column and the influent of tap water is measured, and a comparative analysis is performed to test the adsorption rate of organic matter. The test results are shown in Table 2.

[0112] Table 2 Experimental protocol Organic matter adsorption rate / % Example 1 27.85 Example 2 33.52 Example 3 31.28 Example 4 32.10 Example 5 31.73 Comparative Example 1 31.75 Comparative Example 2 30.86

[0113] From the data of test examples 1 and 2, it can be seen that the average pore size and specific surface area of ​​the regenerated anionic resin prepared in Example 2 are optimal, and the adsorption rate for organic matter is the best.

[0114] The main components of organic impurities adsorbed inside the waste anion resin include humic acid, fulvic acid, low molecular weight organic carboxylic acid, polybasic organic carboxylic acid and other soluble organic matter. These organics are adsorbed on the waste anion resin through van der Waals force and chemical affinity, with low elution rate, which ultimately affects the working exchange capacity of the resin and the quality of the effluent. In addition, some heavy metal ions may also be adsorbed in the waste anion resin, further reducing the treatment effect of the resin.

[0115] In the present invention, the functional agent prepared by using N-acetylcysteine ​​in embodiment 2 is compared with the functional agent prepared by using reduced glutathione in embodiment 3, and shows better performance in the preparation of regenerated anionic resin. The acetyl group of N-acetylcysteine ​​not only increases its stability and water solubility in aqueous solution, but also can act on the active sites of the resin surface to form more micropores and mesopores, thereby significantly increasing the specific surface area and average pore size of the resin. This helps to improve the adsorption capacity of resin to organic matter. In addition, the sulfhydryl group of N-acetylcysteine ​​provides reducing power in the preparation process of the functional agent, protects other components from oxidation, and further enhances the adsorption performance of the resin. In contrast, although reduced glutathione also has reducibility, its molecular weight is larger, and it may not be as good as N-acetylcysteine ​​in the adsorption and permeability of the resin surface, resulting in the formation of pore structure and surface modification effect not as significant as N-acetylcysteine, thereby affecting the organic adsorption rate.

[0116] In the present invention, the functional agent prepared by using carboxylesterase in Example 2 shows better performance in the preparation of regenerated anion resin than the functional agent prepared by using proteinase K in Example 4. Carboxylesterase can effectively hydrolyze compounds containing ester bonds such as organophosphorus pesticides, and has good thermal stability and tolerance to the reaction environment. When treating organic impurities adsorbed inside the waste anion resin, this enzyme can effectively decompose the ester bonds in humic acid, fulvic acid, low-molecular organic carboxylic acids, polybasic organic carboxylic acids and other soluble organic matter, thereby removing these organic impurities. In contrast, proteinase K is mainly targeted at protein organic matter, and is not as effective as carboxylesterase on other types of organic impurities. Therefore, the functional agent using carboxylesterase in Example 2 performs better in terms of average pore size, specific surface area and organic adsorption rate.

[0117] In the present invention, Example 2 uses trans-1,2-cyclohexanediaminetetraacetic acid as a component of the functional agent, and shows better performance in the preparation of regenerated anionic resin than triethylenetetraaminehexaacetic acid used in Example 5 and ethylenediaminetetraacetic acid used in Comparative Example 2. Trans-1,2-cyclohexanediaminetetraacetic acid is a multidentate ligand that can form a highly stable water-soluble complex with metal ions, reduce the negative impact of metal ions on resin performance, and improve the regeneration effect of the resin and the organic matter adsorption rate. In contrast, although triethylenetetraaminehexaacetic acid and ethylenediaminetetraacetic acid can also chelate metal ions, their effects are relatively small.

[0118] In the present invention, Example 2 uses calcium hypochlorite as an oxidant, which shows better performance in the preparation of regenerated anion resin than the sodium persulfate used in Comparative Example 1. Calcium hypochlorite is a strong oxidant that can quickly and effectively oxidize macromolecular organic impurities adsorbed inside the waste anion resin under mild conditions, such as humic acid, fulvic acid, low-molecular organic carboxylic acids, polybasic organic carboxylic acids and other soluble organic matter. These organic substances are adsorbed on the strong base anion resin through van der Waals forces and chemical affinity, and the elution rate is low, which ultimately affects the working exchange capacity of the resin and the effluent quality. The oxidizing effect of calcium hypochlorite can destroy the structure of these organic substances, decomposing them into small molecular substances, which are easier to elute from the resin surface. In addition, the hypochlorite ions (OCl) produced by calcium hypochlorite during the oxidation process - ) can further bind to metal ions on the resin surface (such as iron ions Fe 3+ 、Copper ion Gu 2+ ) to form complexes, reducing the negative impact of metal ions on resin performance, thereby improving the regeneration effect of the resin and the adsorption rate of organic matter. In contrast, although sodium persulfate also has oxidation ability, it may affect the activity of related enzymes, and its effect on improving the pore structure and specific surface area of ​​the resin is not as significant as calcium hypochlorite.

Claims

1. A method for preparing a regenerated anionic resin for water purification, characterized in that: The steps include: Step 1, water washing: the waste anion resin is washed with water in countercurrent; Step 2, calcium hypochlorite oxidation: after the waste anion resin is washed with water, the functional agent is pumped into the regeneration kettle, stirred and soaked, and then the functional agent is removed, and the calcium hypochlorite aqueous solution is pumped into the regeneration kettle for soaking treatment; Step 3, liquid alkali washing: pump 4-6 wt% sodium hydroxide aqueous solution and water into the regeneration kettle for stirring and washing; Step 4, adjusting pH: adjusting the pH value to 4-5 with 4-6wt% hydrochloric acid and water; Step 5, wash with water; The preparation method of the functional agent is as follows: S1, adding sodium pyrophosphate and N-acetylcysteine ​​into water, stirring evenly, to obtain a pretreated product; S2, adding carboxylesterase and sorbitol to the pre-treated material, stirring and mixing, and standing at low temperature, normal pressure, and light-proof conditions to obtain a post-treatment solution; S3, adding post-treatment liquid, calcium hypochlorite and trans-1,2-cyclohexanediaminetetraacetic acid into water, stirring and mixing, and then standing at room temperature, normal pressure and light-proof conditions to obtain the functional agent.

2. The method for preparing a regenerated anionic resin for water purification according to claim 1, characterized in that: The countercurrent washing in step 1 is performed twice. The water from the first washing is used for the second washing after precipitation to remove broken resin impurities. The whole washing process lasts for 0.5 to 2 hours.

3. The method for preparing a regenerated anionic resin for water purification according to claim 1, characterized in that: The mass ratio of the waste anionic resin to the functional agent is 1:4-6.

4. The method for preparing a regenerated anionic resin for water purification according to claim 1, characterized in that: The mass ratio of the waste anionic resin to the calcium hypochlorite aqueous solution is 1:4-6.

5. The method for preparing a regenerated anion resin for water purification according to claim 1, characterized in that: The mass ratio of the waste anion resin, 4-6wt% sodium hydroxide aqueous solution and water is 1:2-4:2-4.

6. The method for preparing a regenerated anionic resin for water purification according to claim 1, characterized in that: The mass ratio of the waste anion resin, 4-6wt% hydrochloric acid and water is 1:2-4:2-4.

7. The method for preparing a regenerated anionic resin for water purification according to claim 1, characterized in that: The preparation method of the functional agent is as follows, in parts by weight: S1, adding 500-700 parts of sodium pyrophosphate and 0.05-0.2 parts of N-acetylcysteine ​​to 1800-2200 parts of water, stirring them thoroughly to mix them evenly, to obtain a pretreated product; S2, add 40-60 parts of carboxylesterase and 400-600 parts of sorbitol to the pretreated material prepared in step S1, stir and mix again, then place at a temperature of 2-8° C., avoid light at normal pressure and stand for 4-8 days to obtain a post-treatment solution; S3. Add 300 to 500 parts of the post-treatment liquid prepared in step S2, 8 to 12 parts of calcium hypochlorite and 18 to 22 parts of trans-1,2-cyclohexanediaminetetraacetic acid into 8000 to 12000 parts of water, stir to fully mix, and let the mixed solution stand for 1 to 3 days at room temperature and pressure to avoid light to obtain a functional agent.

8. A regenerated anion resin for water purification, characterized in that: The method is described in any one of claims 1 to 7.