Macroporous cation exchange resin and method of making and using same

Abstract

A macroporous cation exchange resin and its preparation and application method are disclosed. The method involves dispersing polystyrene-divinylbenzene microspheres in dichloroethane to obtain a microsphere suspension. A sulfonating agent, a mixture of fuming sulfuric acid and chlorosulfonic acid, is then slowly added dropwise under cooling and stirring conditions. After the addition is complete, heating is initiated to trigger a polysulfonation reaction. Once the reaction is complete, the reaction mixture is slowly poured into ice water and continuously stirred and diluted until the solution pH reaches 2.5. The solution is then filtered, washed, and dried to obtain a solid resin. This invention simultaneously introduces a matched number of sulfonic acid groups and sulfone groups onto the polystyrene-divinylbenzene backbone. Utilizing the electron-withdrawing effect of the sulfone groups and the rigid framework they form, the stability of the C-H and C-S bonds in the resin is enhanced. This solves the problems of resin structure damage, rapid decline in separation performance, and significantly shortened service life associated with existing cation exchange resins used in treating chromium plating aging solutions.

Description

Technical Field

[0001] This invention relates to a technology in the field of environmental protection, specifically a macroporous cation exchange resin and its preparation and application methods. Background Technology

[0002] Chromium plating aging solutions are hazardous waste, and their disposal has become a major challenge for the electroplating industry. Existing disposal technologies mainly employ reduction-precipitation methods, but these consume large amounts of reagents, generate significant amounts of chromium precipitate, and have low resource recovery efficiency. Although ion exchange resin methods, such as sulfonated styrene-divinylbenzene cation exchange resins (e.g., D001), can purify impurity cations in wastewater, the purification and separation of Fe from the chromium plating solution remains challenging. 3+ Cr 3+ When impurities are present, the resin faces significant challenges due to high acidity and strong oxidizing properties. The CH bonds in the polymer backbone are easily oxidized and broken, and the CS bonds of the sulfonic acid groups in the backbone are easily degraded and detached, leading to damage to the resin structure, rapid decline in adsorption performance, and a significant reduction in service life, making it difficult to meet the requirements of continuous industrial operation. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention proposes a macroporous cation exchange resin and its preparation and application method. By simultaneously introducing a matching number of sulfonic acid groups and sulfone groups onto the polystyrene-divinylbenzene backbone, the electron-withdrawing effect of the sulfone groups and the rigid backbone formed enhance the stability of the CH and CS bonds in the resin. This solves the problems of resin structure damage, rapid decline in separation performance, and significantly shortened service life that exist in existing cation exchange resins used to treat chromium plating aging solutions.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a method for preparing a macroporous cation exchange resin. The method involves dispersing polystyrene-divinylbenzene microspheres in dichloroethane to obtain a microsphere suspension. Then, a sulfonating agent, a mixture of fuming sulfuric acid and chlorosulfonic acid, is slowly added dropwise under cooling and stirring conditions. After the addition is complete, the mixture is heated to trigger a polysulfonation reaction. Once the reaction is complete, the reaction mixture is slowly poured into ice water and continuously stirred and diluted until the solution pH reaches 2.5. After filtration, washing, and drying, a solid resin is obtained.

[0006] The cooling and stirring process is preferably carried out by placing the mixture in an ice bath and cooling it to 5°C before continuous stirring.

[0007] The polysulfonation reaction refers to: first heating to 60-90℃ and reacting at a constant temperature for 10-16 hours, then heating to 100-130℃ and continuing the reaction at a constant temperature for 24-48 hours to complete the polysulfonation reaction.

[0008] The washing process involves repeatedly washing with deionized water until the filtrate is neutral.

[0009] The drying process is preferably carried out in a constant temperature drying oven at 60°C.

[0010] The polystyrene-divinylbenzene microspheres have a crosslinking degree of 12%, a particle size range of 0.3~1.2 mm, and a weight of 10 g.

[0011] The dichloroethane in question has a volume of 40 mL.

[0012] The fuming sulfuric acid / chlorosulfonic acid mixed sulfonating reagent has a mass ratio of 2:1 to 4:1.

[0013] Technical effect

[0014] This invention utilizes the dissociation of HSO3Cl in an aprotic polar solvent to release an electrophilic sulfonyl ion (SO3H). + SO3H + The attack on the meta position (where steric hindrance is minimal) of the chloromethyl group on the benzene ring in the resin forms a σ-complex of "benzene ring -SO3H". The σ-complex loses one proton, restoring the aromaticity of the benzene ring, ultimately introducing -SO3H onto the benzene ring. Subsequently, a portion of the -SO3H generated after benzene ring sulfonation reacts with excess HSO3Cl to form sulfonyl chloride (-SO2Cl) (benzene ring -SO3H + HSO3Cl → -SO2Cl + H2SO4). The sulfone group (-SO2-) of -SO2Cl is electrophilic and can undergo an electrophilic substitution reaction with another benzene ring in the resin, forming a rigid "benzene ring -SO2-benzene ring" sulfone skeleton scale. A fuming sulfuric acid / chlorosulfonic acid mixed system is used instead of the traditional single concentrated sulfuric acid sulfonating agent to achieve a multi-sulfonation reaction of the polystyrene-divinylbenzene skeleton, simultaneously introducing sulfonic acid groups (-SO3H) required for ion exchange and sulfone groups (-SO2-) for modification onto the resin.

[0015] Compared with existing technologies, this invention uses a fuming sulfuric acid / chlorosulfonic acid mixed sulfonation system to achieve polysulfonation of the polystyrene-divinylbenzene backbone. It simultaneously introduces a matching number of sulfonic acid groups and sulfone groups onto the resin. Through the π-π conjugation effect induced by the sulfone groups, the electron density of the polymer backbone is reduced, and the oxidative breakage of CH and CS bonds is inhibited. At the same time, the rigid aryl-SO2-aryl backbone enhances the structural stability of the resin, thereby fundamentally improving the antioxidant stability of the resin. This solves the technical problem of easy degradation of traditional resins in strong acid and high oxidizing Cr(VI) systems, enabling it to maintain excellent ion exchange performance and recycling performance in strong acid and high oxidizing systems. Attached Figure Description

[0016] Figure 1 This is a schematic diagram and structural diagram of the preparation route of the macroporous cation exchange resin of the present invention and the commercial D001 resin;

[0017] Figure 2 The images show the FTIR spectra of the macroporous cation exchange resin of this invention and the commercial D001 resin.

[0018] Figure 3 This is a comparison of the chemical stability of the macroporous cation exchange resin of the present invention and the commercial D001 resin in different oxidizing media systems.

[0019] Figure 4 This is a comparison chart of the adsorption-regeneration cycle stability of the macroporous cation exchange resin of the present invention and the commercial D001 resin. Detailed Implementation Example 1

[0020] like Figure 1 As shown, this embodiment includes the following steps: 10g of polystyrene-divinylbenzene microspheres with a crosslinking degree of 12% and a particle size range of 0.3~1.2mm were taken and 40mL of dichloroethane was added. The mixture was stirred at room temperature for 24h to swell, resulting in a swollen microsphere suspension. The suspension was cooled to 5°C in an ice bath, and 75g of a sulfonating reagent with a mass ratio of 3:1 (fuming sulfuric acid / chlorosulfonic acid) was slowly added dropwise while continuously stirring. After the addition was complete, the temperature was first raised to 80°C for 14h, and then raised to 120°C for 36h to complete the polysulfonation reaction, resulting in a reaction mixture. The reaction mixture was slowly poured into ice water and continuously stirred to dilute the solution to a pH of 2.5. The solid resin was separated by vacuum filtration and repeatedly washed with deionized water until the filtrate was neutral. Finally, the resin was dried in a 60°C constant temperature drying oven to obtain a sulfone-based macroporous cation exchange resin, which was used to separate and purify Fe from chromium plating solution. 3+ Cr 3+ Impurities.

[0021] Performance tests were performed on the resin: the FTIR spectrum was at 1125 cm⁻¹. -1 1359cm -1 Symmetric and asymmetric stretching vibration peaks of the sulfone group appear at 1237 cm⁻¹. -1 The presence of a S=O stretching vibration peak at the sulfonic acid group indicates the successful introduction of sulfonic acid and sulfone groups; BET testing shows that the resin has a specific surface area of ​​24.25 m²·g. -1 pore volume 0.25 cm³·g -1 The average pore size is 32.32 nm; the resin was placed in a 150 g·L⁻¹ container. -1 In CrO3 solution, after treatment at 70℃ for 96 h, the adsorption capacity loss was only 9.4%, far lower than the 36.7% of traditional D001 resin; after 10 adsorption-regeneration cycles, the resin's adsorption capacity for Fe³⁺ was significantly reduced. + The removal efficiency remained at 84.90%, with a loss of only 8.6%.

[0022] like Figure 2As shown, the macroporous cation exchange resin prepared in this embodiment is at a density of 1237 cm⁻¹. -1 A characteristic S=O stretching vibration peak appeared at 1125 cm⁻¹, indicating the presence of sulfonic acid groups on the surface. -1 and 1359cm -1 The presence of characteristic absorption peaks of the sulfone group confirms the successful introduction of the sulfone group.

[0023] like Figure 3 As shown, the macroporous cation exchange resin prepared in this embodiment has a much lower adsorption capacity loss than the D001 resin in different oxidizing media systems, and its antioxidant properties are significantly improved.

[0024] like Figure 4 As shown, the macroporous cation exchange resin prepared in this embodiment still maintains high impurity removal efficiency after 10 cycles, and its cycle stability is better than that of D001 resin. Compare with Example 1

[0025] Performance tests were conducted using commercially available D001 resin, including: placing the resin in a 150 g·L⁻¹ solution. -1 After treatment in a CrO3 system at 70℃ for 96 hours, the adsorption capacity loss reached 36.7%; after 10 adsorption-regeneration cycles, Fe... 3+ The removal efficiency dropped to 70.76%, with a loss of 22.18%, which is far lower than the resin prepared in Example 1. Compare with Example 2

[0026] This embodiment includes the following steps: 10g of polystyrene-divinylbenzene microspheres with a crosslinking degree of 12% and a particle size range of 0.3~1.2mm were taken and 40mL of dichloroethane was added. The mixture was stirred at room temperature for 24h to swell, resulting in a swollen microsphere suspension. The suspension was cooled to 5°C in an ice bath, and 75g of a 1:1 mass ratio fuming sulfuric acid / chlorosulfonic acid mixed sulfonating reagent was slowly added dropwise while continuously stirring. After the addition was complete, the temperature was first raised to 80°C and reacted for 14h, then raised to 120°C and reacted for 36h to complete the polysulfonation reaction, resulting in a reaction mixture. The reaction mixture was slowly poured into ice water and continuously stirred to dilute the solution to a pH of 2.5. The solid resin was separated by vacuum filtration and repeatedly washed with deionized water until the filtrate was neutral. Finally, the resin was dried in a 60°C constant temperature drying oven to obtain a sulfone-based macroporous cation exchange resin, which was used to separate and purify Fe from chromium plating solution. 3+ Cr 3+ Impurities.

[0027] Performance test results of the obtained resin: at 150g L -1 After treatment in a CrO3, 70℃ system for 96 h, the adsorption capacity loss was 42.1%. After 10 adsorption-regeneration cycles, Fe... 3+ The removal efficiency was 63.2%. Compare with Example 3

[0028] This embodiment includes the following steps: 10g of polystyrene-divinylbenzene microspheres with a crosslinking degree of 12% and a particle size range of 0.3~1.2mm were taken and 40mL of dichloroethane was added. The mixture was stirred at room temperature for 24h to swell, resulting in a swollen microsphere suspension. The suspension was cooled to 5°C in an ice bath, and 75g of a sulfonating reagent with a mass ratio of 6:1 (fuming sulfuric acid / chlorosulfonic acid) was slowly added dropwise while continuously stirring. After the addition was complete, the temperature was first raised to 80°C and reacted for 14h, then raised to 120°C and reacted for 36h to complete the polysulfonation reaction, resulting in a reaction mixture. The reaction mixture was slowly poured into ice water and continuously stirred to dilute the solution to a pH of 2.5. The solid resin was separated by vacuum filtration and repeatedly washed with deionized water until the filtrate was neutral. Finally, the resin was dried in a 60°C constant temperature drying oven to obtain a sulfone-based macroporous cation exchange resin, which was used to separate and purify Fe from chromium plating solution. 3+ Cr 3+ Impurities.

[0029] Performance test results of the obtained resin: at 150g L -1 After treatment in a CrO3, 70℃ system for 96 h, the adsorption capacity loss was 39.21%. After 10 adsorption-regeneration cycles, Fe... 3+ The removal efficiency was 53.1%. Example 2

[0030] This embodiment includes the following steps: 10g of polystyrene-divinylbenzene microspheres with a crosslinking degree of 12% and a particle size range of 0.3~1.2mm were taken and 40mL of dichloroethane was added. The mixture was stirred at room temperature for 24h to swell, resulting in a swollen microsphere suspension. The suspension was cooled to 5°C in an ice bath, and 60g of a 2:1 mass ratio fuming sulfuric acid / chlorosulfonic acid mixed sulfonating reagent was slowly added dropwise while continuously stirring. After the addition was complete, the temperature was first raised to 60°C and reacted for 10h, then raised to 100°C and reacted for 24h to complete the polysulfonation reaction, resulting in a reaction mixture. The reaction mixture was slowly poured into ice water and continuously stirred to dilute the solution to a pH of 2.5. The solid resin was separated by vacuum filtration and repeatedly washed with deionized water until the filtrate was neutral. Finally, the resin was dried in a 60°C constant temperature drying oven to obtain a sulfone-based macroporous cation exchange resin, which was used to separate and purify Fe from chromium plating solution. 3+ Cr 3+ Impurities.

[0031] Performance test results of the obtained resin: at 150 g·L -1 After treatment in a CrO3, 70℃ system for 96 h, the adsorption capacity loss was 10.2%. After 10 adsorption-regeneration cycles, Fe... 3+ The removal efficiency is 83.5%. Example 3

[0032] This embodiment includes the following steps:

[0033] 10 g of polystyrene-divinylbenzene microspheres with a crosslinking degree of 12% and a particle size range of 0.3~1.2 mm were added to 40 mL of dichloroethane and stirred at room temperature for 24 h to swell, resulting in a swollen microsphere suspension. The suspension was cooled to 5 °C in an ice bath, and 80 g of a sulfonating reagent (4:1 mass ratio of fuming sulfuric acid / chlorosulfonic acid) was slowly added dropwise with continuous stirring. After the addition was complete, the temperature was first raised to 90 °C and reacted for 16 h, then raised to 130 °C and reacted for 48 h to complete the polysulfonation reaction, yielding a reaction mixture. The reaction mixture was slowly poured into ice water and diluted with continuous stirring until the solution pH reached 2.5. The solid resin was separated by vacuum filtration, and repeatedly washed with deionized water until the filtrate was neutral. Finally, the resin was dried in a 60 °C constant temperature drying oven to obtain a sulfone-based macroporous cation exchange resin, which was used to separate and purify Fe from chromium plating solution. 3+ Cr 3+ Impurities.

[0034] Performance test results of the obtained resin: at 150 g·L -1 After treatment in a CrO3, 70℃ system for 96 h, the adsorption capacity loss was 8.6%. After 10 adsorption-regeneration cycles, Fe... 3+ The removal efficiency was 85.2%.

[0035] In summary, the preparation process of this invention is simple, the reaction conditions are controllable, and the raw materials are readily available, making it suitable for industrial-scale production. The prepared resin possesses both excellent antioxidant stability and ion exchange selectivity, enabling the deposition of Fe in chromium plating solutions. 3+ Cr 3+ The efficient purification of impurities reduces the cost and energy consumption of waste liquid treatment in the electroplating industry, and promotes the development of clean production and circular economy in the electroplating industry.

[0036] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A method for preparing a macroporous cation exchange resin, characterized in that, After preparing a microsphere suspension by dispersing polystyrene-divinylbenzene microspheres in dichloroethane, a sulfonating agent of fuming sulfuric acid / chlorosulfonic acid was slowly added dropwise under cooling and stirring conditions. After the addition was completed, the mixture was heated to trigger a polysulfonation reaction. After the reaction was complete, the reaction mixture was slowly poured into ice water and stirred continuously to dilute the solution to a pH of 2.

5. After filtration, washing and drying, a solid resin was obtained.

2. The method for preparing the macroporous cation exchange resin according to claim 1, characterized in that, The cooling and stirring process involves placing the container in an ice bath and cooling it to 5°C before continuous stirring.

3. The method for preparing the macroporous cation exchange resin according to claim 1, characterized in that, The polysulfonation reaction refers to: first heating to 60-90℃ and reacting at a constant temperature for 10-16 hours, then heating to 100-130℃ and continuing the reaction at a constant temperature for 24-48 hours to complete the polysulfonation reaction.

4. The method for preparing the macroporous cation exchange resin according to claim 1, characterized in that, The polystyrene-divinylbenzene microspheres have a crosslinking degree of 12%, a particle size range of 0.3~1.2 mm, and a weight of 10 g.

5. The method for preparing the macroporous cation exchange resin according to claim 1, characterized in that, The dichloroethane in question has a volume of 40 mL.

6. The method for preparing the macroporous cation exchange resin according to claim 1, characterized in that, The fuming sulfuric acid / chlorosulfonic acid mixed sulfonating reagent has a mass ratio of 2:1 to 4:

1.

7. An application of a macroporous cation exchange resin prepared by any one of claims 1-6, characterized in that, Used for purifying and separating Fe from chromium plating aging solution 3+ Cr 3+ .

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