Regenerated anion resin for water purification and its preparation method

Abstract

The present invention discloses a regenerated anion resin for water purification and its preparation method, belonging to the technical field of resin regeneration. The specific steps of the method include: water washing, calcium hypochlorite oxidation, caustic soda washing, pH adjustment, cleaning and packaging. Calcium hypochlorite is used to oxidize macromolecular organic impurities, sodium hydroxide is used to remove small molecule organic substances, and hydrochloric acid is used to adjust the pH value. Compared with the prior art, the regenerated anion resin of the present invention shows excellent performance in terms of average pore diameter, specific surface area and organic matter adsorption rate, and is applicable to the field of water treatment, especially application scenarios that require highly efficient regeneration of anion resin to improve water quality.

Description

Technical Field

[0001] The present invention relates to the technical field of resin regeneration, and particularly to a regenerated anion 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 ions (Cl - ), etc., to improve water quality. However, with the increase in the number of uses, the anion exchange resin will gradually adsorb a large amount of organic impurities, such as humic acid, fulvic acid, low-molecular-weight organic carboxylic acid, polybasic organic carboxylic acid, and other soluble organic matters. These organic matters are adsorbed on the strongly basic anion resin through van der Waals forces and chemical affinity, with a low elution rate, ultimately affecting the working exchange capacity and effluent quality of the resin. In addition, some heavy metal ions may also be adsorbed in the waste anion resin, further reducing the treatment effect of the resin.

[0003] The 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, with high energy consumption and may cause damage to the resin structure; although acid-base regeneration can remove some organic matters, the removal effect on macromolecular organic impurities is not good, and the wastewater treatment cost generated is high. Therefore, developing an efficient and environmentally friendly preparation method for regenerated anion resin is of great significance for improving the resin regeneration efficiency and reducing the treatment cost.

[0004] Chinese Patent CN110975851A discloses a method for desorbing and regenerating an organic matter-adsorbing resin, including the step of desorbing and regenerating the organic matter-adsorbing resin with a premixed gas mixture of nitrogen and water vapor; the water vapor in the gas mixture forms an azeotrope with the organic matter adsorbed on the resin, so that the organic matter is discharged from the resin tower along with the gas mixture. Further, the desorbed nitrogen and the gas containing organic matter jointly pass through a molecular sieve for dehydration, where water is absorbed by the molecular sieve, and nitrogen and organic matter are respectively discharged and then the organic matter is recovered by condensation, and nitrogen can be recovered for continued use. Using the method of desorbing and regenerating the resin with the gas mixture of nitrogen and water vapor in this invention, compared with the desorption with pure water vapor at the same pressure, a relatively small amount of vapor can be used in this invention to achieve a level equivalent to the desorption effect of pure water vapor, and it can effectively reduce the amount of wastewater generated after desorption and reduce the wastewater treatment cost. However, there is still room for improvement in the average pore diameter, specific surface area, and organic matter adsorption rate of the resin desorption and regeneration method of this invention. Summary of the Invention

[0005] To address the deficiencies in the prior art, the present invention aims to provide a regenerated anion resin for water purification and its preparation method. Through a series of optimized chemical treatment steps, it effectively removes the macromolecular and small-molecular organic impurities adsorbed inside the waste anion resin, while optimizing the pore structure of the waste anion resin, increasing the specific surface area, and improving the adsorption capacity for organic substances, thereby achieving the efficient regeneration of the waste anion resin and enhancing its application performance in the field of water purification.

[0006] To achieve the above-mentioned invention objectives, the present invention adopts the following technical solutions:

[0007] The preparation method of a regenerated anion resin for water purification is as follows:

[0008] Step 1, water washing: Vacuum pump the waste anion resin with qualified quality inspection into the regeneration kettle pre-equipped with a filter screen, and conduct countercurrent washing with water.

[0009] Step 2, calcium hypochlorite oxidation: After the waste anion resin is completed with water washing, in order to effectively remove a small amount of macromolecular organic impurities adsorbed inside it, pump a 0.1 - 0.3 wt% calcium hypochlorite aqueous solution into the regeneration kettle. Subsequently, open the steam jacket, control the temperature at 35 - 45 °C, and conduct soaking treatment under normal pressure conditions. The soaking duration is 5 - 6 hours. During the soaking process, the stirring device needs to be started continuously for 10 - 15 minutes per hour to ensure that the materials can fully react.

[0010] Step 3, caustic soda washing: After the calcium hypochlorite oxidation treatment, in order to further remove small-molecular organic substances and exchange some sulfate ions and chloride ions adsorbed inside the waste anion resin, pump the pre-prepared 4 - 6 wt% sodium hydroxide aqueous solution and water into the regeneration kettle together; under normal temperature and pressure conditions, conduct stirring treatment, and the stirring duration is 1 - 3 hours to ensure that the materials can be fully washed.

[0011] Step 4, pH adjustment: After the caustic soda washing is completed, in order to adjust the pH value of the solution to an appropriate range, pump the pre-prepared 4 - 6 wt% hydrochloric acid and water into the regeneration kettle together, and conduct stirring treatment under normal temperature and pressure conditions. The stirring duration is 0.5 - 2 hours until the pH value of the solution drops to 4 - 5 and the neutralization reaction ends. During the feeding process of 4 - 6 wt% hydrochloric acid, no hydrochloric acid mist will be generated.

[0012] Step 5, washing: After the pH adjustment is completed, in order to remove a small amount of broken resin that may be generated during the oxidation process, conduct countercurrent washing with water again, and the entire water washing process lasts for 0.3 - 0.8 hours.

[0013] Step 6, packaging: After the above washing steps, vacuum pump the regenerated anion resin into the packaging tank, then conduct discharging and packaging, and finally send the finished product to the finished product warehouse for sale to complete 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: Vacuum pump the waste anion resin with qualified quality inspection into a regeneration kettle pre-equipped with a filter screen, and perform countercurrent washing with water;

[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, pump the functional agent into the regeneration kettle, and perform stirring and soaking treatment under normal pressure conditions. The stirring and soaking time is 3 - 5 hours, then remove the functional agent, pump a 0.1 - 0.3wt% calcium hypochlorite aqueous solution into the regeneration kettle. Subsequently, open the steam jacket, control the temperature at 35 - 45°C, and perform soaking treatment under normal pressure conditions. The soaking time is 5 - 6 hours. During the soaking process, the stirring device needs to be started every hour and stirred continuously for 10 - 15 minutes to ensure that the materials can react fully;

[0017] Step 3, liquid alkali washing: After the calcium hypochlorite oxidation treatment, in order to further remove small molecule organic substances and exchange some sulfate ions and chloride ions adsorbed inside the waste anion resin, pump the pre-prepared 4 - 6wt% sodium hydroxide aqueous solution and water into the regeneration kettle together; under normal temperature and pressure conditions, perform stirring treatment, and the stirring time is 1 - 3 hours to ensure that the materials can be washed fully;

[0018] Step 4, pH adjustment: After the liquid alkali washing is completed, in order to adjust the pH value of the solution to an appropriate range, pump the pre-prepared 4 - 6wt% hydrochloric acid and water into the regeneration kettle together, and perform stirring treatment under normal temperature and pressure conditions. The stirring time is 0.5 - 2 hours until the pH value of the solution drops to 4 - 5 and the neutralization reaction ends. During the feeding process of 4 - 6wt% hydrochloric acid, no hydrochloric acid mist will be generated;

[0019] Step 5, washing: After the pH is adjusted, in order to remove a small amount of broken resin that may be generated during the oxidation process, perform countercurrent washing with water again, and the entire water washing process lasts for 0.3 - 0.8 hours;

[0020] Step 6, packaging: After the above washing steps, vacuum pump the regenerated anion resin into a packaging tank, then perform discharging and packaging, and finally send the finished product to the finished product warehouse for sale to complete the entire preparation process of the regenerated anion resin.

[0021] The countercurrent washing in Step 1 is two - time water washing. After the water after the first water washing removes broken resin impurities through precipitation, it is reused for the second water washing, and the entire water washing process lasts for 0.5 - 2 hours.

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

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

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

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

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

[0027] S1. Add sodium pyrophosphate and N-acetylcysteine to water and stir evenly to obtain a pretreatment product;

[0028] S2. Add carboxylesterase and sorbitol to the pretreatment product, stir and mix, and then let it stand under low temperature, normal pressure and light avoidance conditions to obtain a post-treatment liquid;

[0029] S3. Add the post-treatment liquid, calcium hypochlorite and trans-1,2-cyclohexanediaminetetraacetic acid to water, stir and mix, and then let it stand under normal temperature, normal pressure and light avoidance conditions to obtain the functional agent.

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

[0031] S1. Add 500-700 parts of sodium pyrophosphate and 0.05-0.2 parts of N-acetylcysteine to 1800-2200 parts of water, and stir well to mix evenly to obtain a pretreatment product;

[0032] S2. Add 40-60 parts of carboxylesterase and 400-600 parts of sorbitol to the pretreatment product prepared in step S1, stir and mix again, and then place it at a temperature of 2-8 °C, and let it stand for 4-8 days under normal pressure and avoiding light to obtain a post-treatment liquid;

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

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

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

[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-weight organic carboxylic acids, polycarboxylic acids, and other soluble organic matters. Calcium hypochlorite can destroy the structures of these organic matters, decompose them into small-molecule substances, making it easier to elute from the resin surface and improving the regeneration effect of the resin.

[0037] An aqueous sodium hydroxide solution is used as an alkaline detergent in the caustic soda washing step to further remove the small-molecule organic matters adsorbed inside the waste anion resin and exchange some of the sulfate ions and chloride ions adsorbed inside the resin, improving the purity and performance of the resin.

[0038] Hydrochloric acid is used to adjust the pH value, adjusting the pH value of the solution to an appropriate range (4 - 5), neutralizing the alkaline environment after caustic soda washing, ensuring that the resin undergoes subsequent treatment under neutral or weakly acidic conditions, and improving the stability and adsorption performance of the resin.

[0039] Sodium pyrophosphate is used as a pretreatment agent in the preparation of the functional agent, providing a stable chemical environment, promoting the mixing and reaction of other components, and enhancing the performance of the functional agent.

[0040] N-acetylcysteine is used as a reducing agent and stabilizer, providing reducing power, protecting other components from oxidation, and at the same time increasing the stability and water solubility of the functional agent in aqueous solution.

[0041] Carboxylesterase is used as an enzyme catalyst, which can effectively hydrolyze ester-bond-containing compounds such as organophosphorus pesticides, and decompose the ester bonds in humic acid, fulvic acid, low-molecular-weight organic carboxylic acids, polycarboxylic acids, and other soluble organic matters adsorbed inside the waste anion resin, thereby removing these organic impurities and improving the regeneration effect of the resin.

[0042] Sorbitol is used as a protective agent and stabilizer, providing a mild chemical environment, protecting the activity of the enzyme, preventing the enzyme from inactivating during the treatment process, and at the same time increasing the stability and water solubility of the functional agent.

[0043] Trans-1,2-cyclohexanediaminetetraacetic acid is used as a chelating agent, which can form highly stable water-soluble complexes with metal ions, reducing the negative impact of metal ions on the resin performance, and improving the regeneration effect of the resin and the organic matter adsorption rate.

[0044] These substances act synergistically in the present invention. Through a series of optimized chemical treatment steps, they can effectively remove the organic impurities adsorbed inside the waste anion resin, optimize the pore structure of the resin, increase the specific surface area, improve the adsorption capacity for organic matters, thereby realizing the efficient regeneration of the waste anion resin and enhancing its application performance in the water purification field.

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

[0046] 1) Through optimized chemical treatment steps, including calcium hypochlorite oxidation, caustic soda washing, and pH adjustment, the present invention effectively removes the macromolecular and small-molecular organic impurities adsorbed inside the waste anion resin, significantly improving the purity and performance of the regenerated anion resin. The use of a specific functional agent further enhances the decomposition and removal ability of organic impurities, optimizes the pore structure of the waste anion resin, increases the specific surface area, and thus improves the adsorption ability for organic matter.

[0047] 2) The present invention uses calcium hypochlorite oxidation treatment to break the structure of the organic matter adsorbed inside the waste anion resin, decomposing it into small-molecular substances, which are more easily eluted 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, reducing energy consumption and equipment requirements, lowering the treatment cost. Through optimized treatment steps, the generation of wastewater and waste residues is reduced, the negative impact on the environment is decreased, and at the same time, the safety and sustainability of the treatment process are improved. Specific Embodiments

[0049] Main source of substances:

[0050] The waste anion resin is sourced from the resin used for water purification in the thermal power plants and industrial enterprises that are the service objects of the enterprise (waste resin that has been regenerated more than 50 times for the above enterprises), and does not involve the waste ion exchange resins generated in the processes of hydrometallurgy, surface treatment, and pharmaceutical industry for heavy metal and antibiotic extraction and separation, nor the waste ion exchange resins generated in the industrial wastewater treatment process.

[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 concept 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, caustic soda washing, pH adjustment, cleaning, and packaging, combined with a specific functional agent preparation method. At the same time, the pore structure of the waste anion resin is optimized, the specific surface area is increased, and the adsorption ability for organic matter is improved, thereby achieving the efficient regeneration of the waste anion resin and enhancing its application performance in the water purification field.

[0055] Example 1

[0056] The preparation method of a regenerated anion resin for water purification is as follows:

[0057] Step 1, water washing: Vacuum pump the waste anion resin with qualified quality inspection into a regeneration kettle pre-installed with a filter screen, and carry out countercurrent washing with water. Specifically, it is 2 times of water washing. After the water after the first water washing removes the crushed resin impurities through precipitation, it is 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 completed with water washing, in order to effectively remove a small amount of macromolecular organic impurities adsorbed inside it, pump a 0.2wt% calcium hypochlorite aqueous solution into the regeneration kettle. The mass ratio of the waste anion resin to the calcium hypochlorite aqueous solution is 1:5. Subsequently, open the steam jacket, control the temperature at 40°C, and carry out soaking treatment under normal pressure. The soaking time is 5 hours. During the soaking process, the stirring device needs to be started every hour and stirred continuously for 12 minutes to ensure that the materials can react fully;

[0059] Step 3, caustic soda washing: After the calcium hypochlorite oxidation treatment, in order to further remove small molecule organic substances and exchange part of the sulfate ions (SO4 2- ), chloride ions (Cl - ) adsorbed inside the waste anion resin, pump the pre-prepared 5wt% sodium hydroxide aqueous solution and water into the regeneration kettle together; The mass ratio of the waste anion resin, the 5wt% sodium hydroxide aqueous solution to water is 1:3:3. Under the conditions of normal temperature and pressure, carry out stirring treatment, and the stirring time is 2 hours to ensure that the materials can be washed fully;

[0060] Step 4, pH adjustment: After the caustic soda washing is completed, in order to adjust the pH value of the solution to an appropriate range, pump the pre-prepared 5wt% hydrochloric acid and water into the regeneration kettle together. The mass ratio of the waste anion resin, the 5wt% hydrochloric acid to water is 1:3:3. Under the conditions of normal temperature and pressure, carry out stirring treatment, and the stirring time is 1 hour until the pH value of the solution drops to 4.5 and the neutralization reaction ends. During the feeding process of the 5wt% hydrochloric acid, no hydrochloric acid mist will be generated;

[0061] Step 5, washing: After the pH adjustment is completed, in order to remove a small amount of crushed resin that may be generated during the oxidation process, use water for countercurrent washing again. The whole water washing process lasts for 0.5 hour;

[0062] Step 6, packaging: After the above washing steps, vacuum pump the regenerated anion resin into a packaging tank, then carry out discharging and packaging, and finally send the finished product to the finished product warehouse for sale to complete the preparation process of the whole regenerated anion resin.

[0063] Example 2

[0064] The preparation method of a regenerated anion resin for water purification is as follows:

[0065] Step 1, water washing: The qualified waste anion resin after quality inspection is vacuum pumped into a regeneration kettle pre-installed with a filter screen, and countercurrent washing is carried out with water. Specifically, it is washed twice with water. After the water after the first water wash is precipitated to remove broken resin impurities, it is reused for the second water wash. The entire water wash process lasts for 1 hour;

[0066] Step 2, calcium hypochlorite oxidation: After the waste anion resin is completed with water washing, in order to effectively remove a small amount of macromolecular organic impurities adsorbed inside it, the functional agent is pumped into the regeneration kettle. The mass ratio of the waste anion resin to the functional agent is 1:5. Stirring and soaking treatment is carried out under normal pressure conditions, and the stirring and soaking time is 48 hours. 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. Subsequently, the steam jacket is opened, the temperature is controlled at 40°C, and soaking treatment is carried out under normal pressure conditions. The soaking time is 5 hours. During the soaking process, the stirring device needs to be started every hour and stirred continuously for 12 minutes to ensure that the materials can react fully;

[0067] Step 3, caustic soda washing: After the calcium hypochlorite oxidation treatment, in order to further remove small molecule organic substances and exchange some sulfate ions (SO4 2- ), chloride ions (Cl - ) adsorbed inside the waste anion resin, the pre-prepared 5wt% sodium hydroxide aqueous solution and water are pumped into the regeneration kettle together; the mass ratio of the waste anion resin, the 5wt% sodium hydroxide aqueous solution to water is 1:3:3. Under normal temperature and pressure conditions, stirring treatment is carried out, and the stirring time is 2 hours to ensure that the materials can be washed fully;

[0068] Step 4, pH adjustment: After the caustic soda 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, the 5wt% hydrochloric acid to water is 1:3:3. Under normal temperature and pressure conditions, stirring treatment is carried out, and the stirring time is 1 hour until the pH value of the solution drops to 4.5 and the neutralization reaction ends. During the feeding process of the 5wt% hydrochloric acid, no hydrochloric acid mist will be generated;

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

[0070] Step 6, packaging: After the above washing steps, the regenerated anion resin is vacuum pumped into a packaging tank, and then discharging and packaging are carried out. The final product is sent to the finished product warehouse for sale, and the entire preparation process of the regenerated anion resin is completed.

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

[0072] S1. Add 600 g of sodium pyrophosphate and 100 mg of N-acetylcysteine to 2000 g of water, and stir well to mix evenly to obtain a pretreatment product;

[0073] S2. Add 50 g of carboxylesterase and 500 g of sorbitol to the pretreatment product prepared in step S1, stir and mix again, then place it at a temperature of 3 °C, and let it stand still for 6 days under normal pressure in the dark to obtain a post-treatment liquid;

[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 to 10 kg of water, stir to mix well, and let the mixed solution stand still for 2 days at normal temperature and pressure in the dark to obtain a functional agent.

[0075] Example 3

[0076] A preparation method of a regenerated anion resin for water purification is basically the same as that of Example 2, and the only difference is the preparation method of the functional agent.

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

[0078] S1. Add 600 g of sodium pyrophosphate and 100 mg of reduced glutathione to 2000 g of water, and stir well to mix evenly to obtain a pretreatment product;

[0079] S2. Add 50 g of carboxylesterase and 500 g of sorbitol to the pretreatment product prepared in step S1, stir and mix again, then place it at a temperature of 3 °C, and let it stand still for 6 days under normal pressure in the dark to obtain a post-treatment liquid;

[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 to 10 kg of water, stir to mix well, and let the mixed solution stand still for 2 days at normal temperature and pressure in the dark to obtain a functional agent.

[0081] Example 4

[0082] A preparation method of a regenerated anion resin for water purification is basically the same as that of Example 2, and the only difference is the preparation method of the functional agent.

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

[0084] S1. Add 600 g of sodium pyrophosphate and 100 mg of N-acetylcysteine to 2000 g of water, and stir well to mix evenly to obtain a pretreatment product;

[0085] S2. Add 50 g of proteinase K and 500 g of sorbitol to the pre-treatment product prepared in step S1, stir and mix again, then place it at a temperature of 3°C, and let it stand still for 6 days under normal pressure in the dark to obtain a post-treatment liquid;

[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 to 10 kg of water, stir to mix them thoroughly, and let the mixed solution stand still for 2 days under normal temperature and pressure in the dark to obtain a functional agent.

[0087] Example 5

[0088] A preparation method of a regenerated anion resin for water purification is basically the same as that of Example 2, and the only difference is the preparation method of the functional agent.

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

[0090] S1. Add 600 g of sodium pyrophosphate and 100 mg of N-acetylcysteine to 2000 g of water, stir thoroughly to mix them evenly to obtain a pre-treatment product;

[0091] S2. Add 50 g of carboxylesterase and 500 g of sorbitol to the pre-treatment product prepared in step S1, stir and mix again, then place it at a temperature of 3°C, and let it stand still for 6 days under normal pressure in the dark to obtain a post-treatment liquid;

[0092] S3. Add 400 g of the post-treatment liquid prepared in step S2, 10 g of calcium hypochlorite, and 20 g of triethylenetetraminehexaacetic acid to 10 kg of water, stir to mix them thoroughly, and let the mixed solution stand still for 2 days under normal temperature and pressure in the dark to obtain a functional agent.

[0093] Comparative Example 1

[0094] A preparation method of a regenerated anion resin for water purification is basically the same as that of Example 2, and the only difference is the preparation method of the functional agent.

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

[0096] S1. Add 600 g of sodium pyrophosphate and 100 mg of N-acetylcysteine to 2000 g of water, stir thoroughly to mix them evenly to obtain a pre-treatment product;

[0097] S2. Add 50 g of carboxylesterase and 500 g of sorbitol to the pre-treatment product prepared in step S1, stir and mix again, then place it at a temperature of 3°C, and let it stand still for 6 days under normal pressure in the dark to obtain a post-treatment liquid;

[0098] S3. Add 400 g of the post-treatment liquid prepared in step S2, 10 g of sodium persulfate, and 20 g of trans-1,2-cyclohexanediaminetetraacetic acid to 10 kg of water, stir to mix them thoroughly, and let the mixed solution stand for 2 days at normal temperature and pressure in the dark to obtain the functional agent.

[0099] Comparative Example 2

[0100] A method for preparing regenerated anion resin for water purification is basically the same as that in Example 2, except that the preparation method of the functional agent is different.

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

[0102] S1. Add 600 g of sodium pyrophosphate and 100 mg of N-acetylcysteine to 2000 g of water, stir thoroughly to mix them evenly to obtain the pretreatment product;

[0103] S2. Add 50 g of carboxylesterase and 500 g of sorbitol to the pretreatment product prepared in step S1, stir and mix again, then place it at a temperature of 3 °C and let it stand for 6 days at normal pressure in the dark to obtain the post-treatment liquid;

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

[0105] Test Example 1

[0106] Average pore size and specific surface area

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

[0108] Table 1

[0109] Experimental Scheme 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

[0110] Test Example 2

[0111] Organic matter adsorption rate test

[0112] The molecular weight distribution of organic matter in water is determined by ultrafiltration method. Install the regenerated anion resin prepared in the present invention in the adsorption column, pass the tap water in Shanghai through it, measure the molecular weight distribution of organic matter in the effluent of the adsorption column and the influent tap water, and conduct comparative analysis to test the organic matter adsorption rate. The test results are shown in Table 2.

[0113] Table 2

[0114] Experimental Scheme 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

[0115] From the data of Test Examples 1 to 2, it can be seen that the average pore size and specific surface area of the regenerated anion resin prepared in Example 2 are the best, and the adsorption rate of organic matter is the best.

[0116] The main components of the organic impurities adsorbed inside the waste anion resin include humic acid, fulvic acid, low-molecular-weight organic carboxylic acids, polycarboxylic acids, and other soluble organic matters. These organic matters are adsorbed on the waste anion resin through van der Waals forces and chemical affinity, with a low elution rate, ultimately affecting the working exchange capacity and effluent quality of the resin. In addition, some heavy metal ions may also be adsorbed in the waste anion resin, further reducing the treatment effect of the resin.

[0117] In the present invention, the functional agent prepared using N-acetylcysteine in Example 2 exhibits better performance than the functional agent prepared using reduced glutathione in Example 3 in the preparation of the regenerated anion resin. The acetyl group of N-acetylcysteine not only increases its stability and water solubility in aqueous solution, but also can interact with the active sites on 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 the resin for organic matter. In addition, the sulfhydryl group of N-acetylcysteine provides reducing power during the preparation of the functional agent to protect other components from oxidation, further enhancing the adsorption performance of the resin. In contrast, although reduced glutathione also has reducibility, its molecular weight is relatively large, and its adsorption and penetration ability on the resin surface may be inferior to that of N-acetylcysteine, resulting in a less significant pore structure formation and surface modification effect than N-acetylcysteine, thus affecting the adsorption rate of organic matter.

[0118] In the present invention, the functional agent prepared using carboxylesterase in Example 2 exhibits better performance than the functional agent prepared using Proteinase K in Example 4 in the preparation of the regenerated anion resin. Carboxylesterase can effectively hydrolyze ester bond-containing compounds such as organophosphorus pesticides and has good thermal stability and tolerance to the reaction environment. When this enzyme is used to treat the organic impurities adsorbed inside the waste anion resin, it can effectively break the ester bonds in humic acid, fulvic acid, low-molecular-weight organic carboxylic acids, polycarboxylic acids, and other soluble organic matters, thereby removing these organic impurities. In contrast, Proteinase K mainly targets proteinaceous organic matters and is less effective than carboxylesterase for other types of organic impurities. Therefore, the functional agent using carboxylesterase in Example 2 shows better performance in terms of average pore size, specific surface area, and adsorption rate of organic matter.

[0119] In the present invention, in Example 2, trans-1,2-cyclohexanediaminetetraacetic acid is used as a component of the functional agent, which shows better performance in the preparation of regenerated anion resin compared with diethylenetriaminepentaacetic 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 highly stable water-soluble complexes with metal ions, reducing the negative impact of metal ions on the resin performance and improving the resin regeneration effect and organic matter adsorption rate. In contrast, although diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid can also chelate metal ions, their effects are relatively small.

[0120] In the present invention, in Example 2, calcium hypochlorite is used as the oxidant, which shows better performance in the preparation of regenerated anion resin compared with sodium persulfate used in Comparative Example 1. Calcium hypochlorite is a strong oxidant that can rapidly and effectively oxidize the macromolecular organic impurities adsorbed inside the waste anion resin, such as humic acid, fulvic acid, low-molecular-weight organic carboxylic acids, polybasic organic carboxylic acids, and other soluble organic matters, under mild conditions. These organic matters are adsorbed on the strongly basic anion resin through van der Waals forces and chemical affinity, with low elution rate, ultimately affecting the working exchange capacity and effluent quality of the resin. The oxidation of calcium hypochlorite can destroy the structures of these organic matters, decomposing them into small-molecule substances, which are thus more easily eluted from the resin surface. In addition, the hypochlorite ions (OCl - −) generated during the oxidation process of calcium hypochlorite can further form complexes with the metal ions (such as iron ions Fe 3+ 3+, copper ions Cu 2+ 2+) on the resin surface, reducing the negative impact of metal ions on the resin performance, thereby improving the resin regeneration effect and organic matter adsorption rate. 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 that of 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, 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, adding 300-500 parts of the post-treatment solution prepared in step S2, 8-12 parts of calcium hypochlorite and 18-22 parts of trans-1,2-cyclohexanediaminetetraacetic acid to 8000-12000 parts of water, stirring to fully mix, and leaving the mixed solution at room temperature and pressure to avoid light for 1-3 days to obtain a functional agent; The waste anion resins are derived from resins used for water purification in thermal power plants and industrial enterprises, and are ordinary waste resins that have been regenerated more than 50 times. They 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.

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. A regenerated anion resin for water purification, characterized in that: The method is described in any one of claims 1 to 6.