A composite resin for removing metal ions, a preparation method thereof, and an application thereof

Abstract

The application discloses a kind of composite resin for removing metal ions and its preparation method and application, belong to resin material technical field.The application provides a kind of composite resin with weak acid cation functional group and nitrogen-containing chelating functional group for overcoming the problem that the removal rate of heavy metal in the solution with alkali metal and heavy metal simultaneously is poor in traditional cation exchange resin.The composite resin in the application contains nitrogen-containing oxygen chelating functional group and weak acid cation functional group, nitrogen-containing oxygen chelating functional group can selectively remove heavy metal ions such as chromium, and weak acid cation functional group can effectively remove alkali metal ions such as calcium, so that the composite resin in the application has the advantages of both cation exchange resin and chelating resin, which can effectively remove heavy metal ions and alkali metal ions in ethanolamine stock solution.The metal ion concentration in ethanolamine solution treated by the composite resin in the application is less than 30 ppb.

Description

Technical Field

[0001] The present invention belongs to the technical field of resin materials, and in particular relates to a composite resin for removing metal ions, a preparation method and an application thereof. Background Art

[0002] Ethanolamine and its downstream products are widely used in various industrial fields, such as cosmetics, detergents, and electroplating solutions. The presence of metal ions may affect the quality and performance of these products, such as stability, safety, pH, and cleaning and electroplating performance. Therefore, removing metal ions from ethanolamine is crucial to improving product quality. Ion exchange can efficiently remove metal ions from ethanolamine to very low concentrations. It is also simple to operate, can regenerate ion exchange resins, and is economical, making it a commonly used method for metal ion removal.

[0003] Ion exchange resins are polymer materials with ion exchange capabilities. They operate by exchanging ions on the resin with ions in the solution, thereby removing specific ions from the solution. Cation exchange resins contain functional groups, such as sulfonic acid and carboxyl groups, that attract and bind positively charged ions, such as metal ions and organic cations. These resins adsorb cations through electrostatic interactions and simultaneously release existing cations (such as hydrogen and sodium ions) on the resin, thereby achieving ion exchange. Weakly acidic cation exchange resins typically have a high exchange capacity, enabling them to adsorb and exchange more cations when processing large volumes of solution, improving treatment efficiency. Furthermore, their relatively low acid consumption reduces the cost and environmental impact of regeneration. Ion exchange resins are particularly advantageous for purification and desalination. However, the presence of large amounts of salt or alkaline (earth) metal salts in the solution directly competes with heavy metal ions for adsorption sites, significantly reducing the resin's exchange capacity for the target heavy metals and severely limiting its selective removal of heavy metal ions. Chelating resins are a class of cross-linked functional polymers capable of forming multi-coordination complexes with metal ions. They utilize their lone-pair electrons to form coordination bonds with the empty orbitals of metal ions. Chelating resins offer advantages not found in ion exchange resins, such as strong metal selectivity, rapid adsorption rates, and robust binding. Furthermore, chelating resins can rapidly capture metal ions and readily release captured metal ions under specific circumstances, making them an excellent material for adsorbing heavy metal ions. Utilizing the complexation between chelating resins and heavy metals for selective adsorption and separation can effectively mitigate the negative effects of coexisting inorganic salts. Summary of the Invention

[0004] In view of the above-mentioned prior art, the present invention provides a composite resin for removing metal ions, a preparation method and application thereof, so as to solve the technical problem that the existing resin materials are difficult to remove metal ions.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is to provide a method for preparing a composite resin for removing metal ions, comprising the following steps:

[0006] S1: adding chloromethylated polystyrene resin to N,N-dimethylformamide and allowing it to swell for 10-15 hours, then dissolving the swelled chloromethylated polystyrene resin, diethyl malonate, and anhydrous potassium carbonate in a first solvent, and reacting at 60-70°C for 6-10 hours; then filtering, washing, and drying to obtain a first intermediate product;

[0007] S2: adding the first intermediate product to N,N-dimethylformamide and allowing it to swell for 10-15 hours, then dissolving the swollen first intermediate product, diethyl iminodiacetate, and anhydrous potassium carbonate in a second solvent, and reacting at 75-85°C for 4-8 hours; then filtering, washing, and drying to obtain a second intermediate product;

[0008] S3: Add the second intermediate product to N,N-dimethylformamide and swell for 10 to 15 hours, then dissolve the swelled second intermediate product and sodium hydroxide in a mixed solvent and heat under reflux for 8 to 10 hours; then filter and wash, then add the washed product to a 1 M hydrochloric acid solution, stir for 8 hours, filter, wash, and dry to obtain; the mixed solvent is obtained by mixing N,N-dimethylformamide and water.

[0009] On the basis of the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, the swelling time in S1, S2, and S3 was all 12 h.

[0011] Furthermore, the mass ratio of diethyl malonate and anhydrous potassium carbonate to chloromethylated polystyrene resin in S1 is 4-5:7-8:10.

[0012] Furthermore, the first solvent in S1 is N,N-dimethylformamide; the reaction temperature is 65° C., and the reaction time is 8 h.

[0013] Furthermore, the mass ratio of diethyl iminodiacetate and anhydrous potassium carbonate to the first intermediate product in S2 is 41~42:7~8:11~12.

[0014] Furthermore, the second solvent in S2 is N,N-dimethylformamide; the reaction temperature is 80° C., and the reaction time is 6 h.

[0015] Furthermore, the ratio of sodium hydroxide to the second intermediate product in S3 is 17~18:13~14.

[0016] Furthermore, the mixed solvent in S3 is prepared by mixing equal volumes of N,N-dimethylformamide and water; and the heating reflux time is 9 h.

[0017] The invention also discloses a composite resin for removing metal ions, which is prepared by adopting the above preparation method.

[0018] The present invention also discloses an application of a composite resin for removing metal ions, specifically using the composite resin for removing metal ions to remove metal ions in ethanolamine.

[0019] The beneficial effects of the present invention are:

[0020] To overcome the poor heavy metal removal efficiency of conventional cation exchange resins in solutions containing both alkali metals and heavy metals, the present invention provides a composite resin having both weakly acidic cationic functional groups and nitrogen-containing chelating functional groups. The composite resin of the present invention contains nitrogen-containing oxygen chelating functional groups and weakly acidic cationic functional groups. The nitrogen-containing oxygen chelating functional groups selectively remove heavy metal ions such as chromium, while the weakly acidic cationic functional groups effectively remove alkali metal ions such as calcium. Thus, the composite resin of the present invention combines the advantages of both cation exchange resins and chelating resins, effectively removing heavy metal ions and alkali metal ions from ethanolamine stock solutions. The metal ion concentration in ethanolamine solutions treated with the composite resin of the present invention is less than 30 ppb. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A process roadmap for preparing composite resins for removing metal ions;

[0022] Figure 2 This is the infrared spectrum of the composite resin used to remove metal ions;

[0023] Figure 3 Thermogravimetric curves of different resins;

[0024] Figure 4 Schematic diagram of the device for treating ethanolamine solution using composite resin. DETAILED DESCRIPTION

[0025] The specific implementation methods of the present invention are described in detail below with reference to the embodiments.

[0026] Example 1

[0027] A composite resin (PCR) for removing metal ions, the preparation process of which is shown in the following diagram: Figure 1 As shown, the preparation process specifically includes the following steps:

[0028] (1) Chloromethylated polystyrene resin ( Figure 1Compound 1 (purchased from Adamas, CAS: 55844-94-5) was used as a raw material, 10.0 g of chloromethylated polystyrene resin was added to 20 mL of N,N-dimethylformamide and swelled at room temperature for 12 h; then the swollen chloromethylated polystyrene resin, 4.4 g of diethyl malonate and 7.6 g of anhydrous potassium carbonate were added to a round-bottom flask, and N,N-dimethylformamide was added as a solvent. After complete dissolution, the mixture was reacted at 65°C for 8 h; after the reaction was completed, the reaction solution was filtered, and the filter cake was collected and washed three times with deionized water and ethanol, respectively, and then placed in a vacuum drying oven and dried to obtain compound 2.

[0029] (2) 11.8 g of compound 2 was added to 20 mL of N,N-dimethylformamide and swelled at room temperature for 12 h. The swollen compound 2, 41.4 g of diethyl iminodiacetate and 7.6 g of anhydrous potassium carbonate were then added to a round-bottom flask. N,N-dimethylformamide was added as a solvent. After complete dissolution, the mixture was reacted at 80 °C for 6 h. After the reaction was completed, the reaction solution was filtered, and the filter cake was collected and washed three times with deionized water and ethanol respectively. It was then placed in a vacuum drying oven and dried to obtain compound 3.

[0030] (3) 13.6 g of compound 3 was added to 20 mL of N,N-dimethylformamide and swelled at room temperature for 12 h; then the swelled compound 3 and 17.5 g of sodium hydroxide were added to a round-bottom flask, and a mixed solution of N,N-dimethylformamide and water in a volume ratio of 1:1 was added as a solvent, and the mixture was heated under reflux for 9 h; after the reaction, the obtained reaction solution was filtered, and the filter cake was collected and washed with deionized water and ethanol three times respectively; then the washed product was added to a 1 M hydrochloric acid solution and stirred for 8 h, filtered, washed with deionized water and ethanol three times respectively, and then placed in a vacuum drying oven and dried to obtain a composite resin PCR for removing metal ions.

[0031] Example 2

[0032] A composite resin (PCR) for removing metal ions, the preparation process of which is shown in the following diagram: Figure 1 As shown, the preparation process specifically includes the following steps:

[0033] (1) Chloromethylated polystyrene resin ( Figure 1Compound 1 (purchased from Adamas, CAS: 55844-94-5) was used as a raw material, 10.0 g of chloromethylated polystyrene resin was added to 20 mL of N,N-dimethylformamide and swelled at room temperature for 10 h; then the swollen chloromethylated polystyrene resin, 4 g of diethyl malonate and 7 g of anhydrous potassium carbonate were added to a round-bottom flask, and N,N-dimethylformamide was added as a solvent. After complete dissolution, the mixture was reacted at 60°C for 10 h; after the reaction was completed, the reaction solution was filtered, and the filter cake was collected and washed three times with deionized water and ethanol, respectively, and then placed in a vacuum drying oven and dried to obtain compound 2.

[0034] (2) 11 g of compound 2 was added to 20 mL of N,N-dimethylformamide and swelled at room temperature for 10 h. The swollen compound 2, 41 g of diethyl iminodiacetate and 7 g of anhydrous potassium carbonate were then added to a round-bottom flask. N,N-dimethylformamide was added as a solvent. After complete dissolution, the mixture was reacted at 75 °C for 8 h. After the reaction was completed, the reaction solution was filtered, and the filter cake was collected and washed three times with deionized water and ethanol respectively. It was then placed in a vacuum drying oven and dried to obtain compound 3.

[0035] (3) 13 g of compound 3 was added to 20 mL of N,N-dimethylformamide and swelled at room temperature for 10 h; then the swelled compound 3 and 17 g of sodium hydroxide were added to a round-bottom flask, and a mixed solution of N,N-dimethylformamide and water in a volume ratio of 1:1 was added as a solvent, and the mixture was heated under reflux for 8 h; after the reaction, the obtained reaction solution was filtered, and the filter cake was collected and washed with deionized water and ethanol three times respectively; then the washed product was added to a 1 M hydrochloric acid solution and stirred for 8 h, filtered, washed with deionized water and ethanol three times respectively, and then placed in a vacuum drying oven and dried to obtain a composite resin PCR for removing metal ions.

[0036] Example 3

[0037] A composite resin (PCR) for removing metal ions, the preparation process of which is shown in the following diagram: Figure 1 As shown, the preparation process specifically includes the following steps:

[0038] (1) Chloromethylated polystyrene resin ( Figure 1Compound 1 (purchased from Adamas, CAS: 55844-94-5) was used as a raw material, 10.0 g of chloromethylated polystyrene resin was added to 20 mL of N,N-dimethylformamide and swelled at room temperature for 15 h; then the swollen chloromethylated polystyrene resin, 5 g of diethyl malonate and 8 g of anhydrous potassium carbonate were added to a round-bottom flask, and N,N-dimethylformamide was added as a solvent. After complete dissolution, the mixture was reacted at 70°C for 6 h; after the reaction was completed, the reaction solution was filtered, and the filter cake was collected and washed three times with deionized water and ethanol, respectively, and then placed in a vacuum drying oven and dried to obtain compound 2.

[0039] (2) Add 12 g of compound 2 to 20 mL of N,N-dimethylformamide and swell at room temperature for 15 h. Then, add the swollen compound 2, 42 g of diethyl iminodiacetate and 8 g of anhydrous potassium carbonate into a round-bottom flask, add N,N-dimethylformamide as solvent, and react at 85 °C for 4 h after complete dissolution. After the reaction is completed, filter the reaction solution, collect the filter cake and wash it with deionized water and ethanol three times respectively, then place it in a vacuum drying oven and dry it to obtain compound 3.

[0040] (3) 14 g of compound 3 was added to 20 mL of N,N-dimethylformamide and swelled at room temperature for 15 h; then the swelled compound 3 and 18 g of sodium hydroxide were added to a round-bottom flask, and a mixed solution of N,N-dimethylformamide and water in a volume ratio of 1:1 was added as a solvent, and the mixture was heated under reflux for 10 h; after the reaction, the obtained reaction solution was filtered, and the filter cake was collected and washed with deionized water and ethanol three times respectively; then the washed product was added to a 1 M hydrochloric acid solution and stirred for 8 h, filtered, washed with deionized water and ethanol three times respectively, and then placed in a vacuum drying oven and dried to obtain a composite resin PCR for removing metal ions.

[0041] Result Analysis

[0042] The composite resins for removing metal ions prepared in Examples 1 to 3 have similar performances. The composite resin for removing metal ions prepared in Example 1 is taken as an example to illustrate the performance of the composite resin for removing metal ions.

[0043] 1. Characterization of composite resins for metal ion removal

[0044] (1) Infrared spectrum test

[0045] The molecular structure of the composite resin was determined using a Spectrum Two Fourier infrared spectrometer. Potassium bromide tablets were used to prepare the sample. The composite resin PCR and potassium bromide were dried in a vacuum drying oven before testing. The test results are shown in the figure. Figure 2 As shown. Figure 2 It can be seen that 1729 cm -1 The C=O stretching vibration peak appeared at 2500~3600 cm -1 The -OH stretching vibration peak of the carboxyl group appears at 1020~1360 cm -1 The CN stretching vibration peak of tertiary amine appeared at , indicating that the chelating functional group containing nitrogen elements was successfully grafted.

[0046] (2) Elemental analysis test

[0047] The elemental content of the composite resin was determined using an Elementar Unicube elemental analyzer. The chelating functional group content of the composite resin can be inferred based on the nitrogen content of the composite resin. The elemental analysis results are shown in Table 1.

[0048] Table 1 Elemental analysis results

[0049]

[0050] The elemental analysis results also proved that the two functional groups were successfully grafted onto the chloromethylated polystyrene. By calculation, x=0.44 and y=0.56 in the composite resin were obtained, thus determining the molecular formula of the composite resin PCR as shown in Formula I.

[0051]

[0052] (3) Thermogravimetric analysis

[0053] The thermal stability of the composite resin was analyzed and tested using a NETZSCH TG209F1 thermogravimetric analyzer, using nitrogen as the protective atmosphere and a heating rate of 10 °C / min. The composite resin was compared with the corresponding cation exchange resin (compound represented by Formula II) and chelating resin (compound represented by Formula III). The thermogravimetric curves of the three are shown in Figure 2. Figure 3 As shown. Figure 3 As can be seen, the temperatures at which composite resin PCR, chelating resin, and cation exchange resin lose 5% weight are 223°C, 201°C, and 229°C, respectively, with little difference between the three. At 320°C, composite resin PCR loses only 21% of its weight, significantly better than the corresponding chelating resin (36%) and cation exchange resin (34%).

[0054]

[0055] Thermogravimetric analysis results show that the composite resin PCR prepared by the grafting reaction of the present invention has good thermal stability, and the introduction of two functional groups will not affect the heat resistance of the resin itself.

[0056] 2. Performance test of composite resin for removing metal ions

[0057] First, rinse the glass column with deionized water several times, fill the prepared composite resin PCR into the glass column (filling height is 20 cm), then add monoethanolamine and diethanolamine stock solutions from the top, use a pressure pump to pressurize at a constant pressure, and collect the treated monoethanolamine and diethanolamine solutions from the bottom of the glass column. The schematic diagram of the experimental device is shown in the figure. Figure 4 The metal ion concentrations of monoethanolamine and diethanolamine stock solutions are shown in Table 2.

[0058] Table 2 Metal ion concentrations in monoethanolamine and diethanolamine stock solutions

[0059]

[0060] As can be seen from Table 2, the ethanolamine stock solution mainly contained excessive levels of iron, calcium, and chromium. The treated solution after the composite resin column treatment was subjected to ICP-MS testing to determine the metal ion concentrations. The test results are shown in Table 3.

[0061] Table 3 Metal ion concentrations in monoethanolamine and diethanolamine after composite resin treatment

[0062]

[0063] As shown in Table 3, after treatment with the composite resin, the average chromium and iron contents in monoethanolamine and diethanolamine decreased from 0.1540 / 0.2574 ppm and 0.2549 / 0.2332 ppm to 0.0077 / 6.6076 ppb and 0.0058 / 5.0226 ppb, respectively. This indicates that the introduction of nitrogen- and oxygen-containing chelating functional groups enables the composite resin to selectively remove heavy metals such as chromium and iron. Furthermore, the average content of calcium, a relatively high alkali metal, decreased from 0.2604 / 0.6606 ppm to 25.7737 / 20.8245 ppb, effectively removed by the introduction of cationic functional groups.

[0064] The experimental results show that the composite resin PCR of the present invention has a good removal effect on alkali metal ions and heavy metal ions in the ethanolamine stock solution, and the concentrations of various metal ions are all within 30 ppb.

[0065] Although the specific embodiments of the present invention have been described in detail in conjunction with the embodiments, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for preparing a composite resin for removing metal ions, characterized in that: The following steps are involved: S1: adding chloromethylated polystyrene resin to N,N-dimethylformamide and allowing it to swell for 10-15 hours, then dissolving the swelled chloromethylated polystyrene resin, diethyl malonate, and anhydrous potassium carbonate in a first solvent, and reacting at 60-70° C. for 6-10 hours; then filtering, washing, and drying to obtain a first intermediate product; S2: adding the first intermediate product to N,N-dimethylformamide and allowing it to swell for 10-15 hours, then dissolving the swollen first intermediate product, diethyl iminodiacetate, and anhydrous potassium carbonate in a second solvent, and reacting at 75-85°C for 4-8 hours; then filtering, washing, and drying to obtain a second intermediate product; S3: The second intermediate product is added to N,N-dimethylformamide and swelled for 10 to 15 hours, and then the swelled second intermediate product and sodium hydroxide are co-dissolved in a mixed solvent and heated under reflux for 8 to 10 hours; then filtered and washed, and then the washed product is added to a 1 M hydrochloric acid solution, stirred for 8 hours, filtered, washed, and dried to obtain; the mixed solvent is obtained by mixing N,N-dimethylformamide and water.

2. The preparation method according to claim 1, wherein: The swelling time in S1, S2, and S3 was 12 h.

3. The preparation method according to claim 1, wherein: The mass ratio of diethyl malonate and anhydrous potassium carbonate to chloromethylated polystyrene resin in S1 is 4-5:7-8:

10.

4. The preparation method according to claim 3, wherein: The first solvent in S1 is N,N-dimethylformamide; the reaction temperature is 65°C, and the reaction time is 8 h.

5. The preparation method according to claim 1, wherein: The mass ratio of diethyl iminodiacetate and anhydrous potassium carbonate to the first intermediate product in S2 is 41~42:7~8:11~12.

6. The preparation method according to claim 5, characterized in that: The second solvent in S2 is N,N-dimethylformamide; the reaction temperature is 80°C, and the reaction time is 6 h.

7. The preparation method according to claim 1, wherein: The ratio of sodium hydroxide to the second intermediate product in S3 is 17~18:13~14.

8. The preparation method according to claim 7, characterized in that: The mixed solvent in S3 is a mixture of equal volumes of N,N-dimethylformamide and water; the heating reflux time is 9 h.

9. A composite resin for removing metal ions prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the composite resin for removing metal ions according to claim 9 in removing metal ions from ethanolamine.

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