Process for the preparation of a modified ion exchange resin and its use

Abstract

The application discloses a preparation method of modified ion exchange resin and application thereof, and relates to the technical field of water treatment materials. Resin, EDC.HCl and L-arginine are proportionally immersed into a solution system with pH being 5 (the solution system with pH being 5 is obtained by adjusting 1% dilute hydrochloric acid), to obtain solution A, the solution A is heated to 35-45 DEG C and placed in a magnetic stirring pot, the stirring speed is set to 280-300 rpm, and the reaction is continuously carried out for 5-6 hours, to obtain resin B and residual liquid B, the resin B is washed with deionized water and anhydrous ethanol alternately for 5-6 times, until the filtrate is neutral; the resin B is placed in a vacuum drying box, the temperature is set to 55-60 DEG C, the vacuum degree is set to -0.09 MPa, and the drying is continuously carried out until the weight is constant, to obtain the modified ion exchange resin. The grafting of L-arginine increases more active sites of the resin, the nickel ions can be effectively combined with the resin, and the adsorption capacity of the resin for the nickel ions is improved.

Description

Technical Field

[0001] This invention relates to the technical field of water treatment materials, specifically a method for preparing a modified ion exchange resin and its application. Background Technology

[0002] Electroless nickel plating is widely used in electronics, automotive, and aerospace industries due to its non-current-driven autocatalytic precipitation characteristics and excellent coating uniformity. However, the nickel plating wastewater generated by this process has a complex composition, and nickel ions can accumulate in organisms after entering the water, affecting their normal physiological functions. Current treatment methods for electroless nickel plating wastewater mainly include chemical precipitation, advanced oxidation, adsorption, electrochemical methods, and ion exchange. Traditional methods are difficult to achieve efficient removal and resource recovery of nickel; therefore, there is an urgent need to develop adsorption materials with both high adsorption capacity and strong adsorption properties. Summary of the Invention

[0003] To address the aforementioned problems, specifically those raised in the background section, this invention provides a method for preparing a modified ion exchange resin and its application. The specific technical solution is as follows: A method for preparing a modified ion exchange resin includes the following steps: (1) Dissolve D401 resin in anhydrous ethanol and soak for 6 hours. Then pretreat the resin with dilute hydrochloric acid to the hydrogen form, so that the resin skeleton can be fully expanded to prepare for subsequent group grafting. Then weigh D401 resin, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) and L-arginine in a solution system with pH 5±0.2 to obtain solution A. (2) Heat solution A to 35-45℃ and place it in a magnetic stirring pot. Set the stirring speed to 280-300 rpm and continue the reaction for 5-6 hours to obtain resin B and residual liquid B. Filter residual liquid B and wash resin B with deionized water and ethanol alternately 5-6 times until the filtrate is neutral. (3) Place resin B in a vacuum drying oven, set the temperature to 55-60℃ and the vacuum degree to -0.09MPa, and continue drying until constant weight to obtain modified ion exchange resin.

[0004] Specifically, the D401 resin is a chelated iminodiacetic acid macroporous styrene copolymer crosslinked polymer ion exchange resin.

[0005] Specifically, during the pretreatment of D401 resin, it is soaked in dilute hydrochloric acid with a concentration of 35g / L-55g / L for 2 hours.

[0006] Specifically, the mass-to-volume ratio of the D401 resin to EDC·HCl and L-arginine is (1-2):1.5:1.

[0007] Specifically, the solution system with a pH of 5 ± 0.2 is obtained by adjusting it with dilute hydrochloric acid solution.

[0008] Specifically, the drying conditions are as follows: at a temperature of 55-60℃, the vacuum degree is maintained at around -0.09MPa, and the drying time is not less than 6 hours, until the resin is dried to a stable state and uniform color.

[0009] Specifically, the ethanol used in the preparation method is anhydrous ethanol with a concentration of 99.5%.

[0010] Application of a modified ion exchange resin prepared according to the above method in the adsorption of nickel ions in nickel plating wastewater.

[0011] The beneficial technical effects of this invention are as follows: First, the D401 resin is fully swollen with ethanol and then pretreated to the hydrogen form with dilute hydrochloric acid. The resin swollen in the ethanol system reacts more thoroughly, allowing the resin skeleton to expand fully, preparing for subsequent group grafting. D401 resin, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and L-arginine are mixed in a dilute hydrochloric acid solution at pH 5 according to a specific ratio. During heating, the collision frequency of carboxyl and amino molecules increases significantly, thereby promoting the amino acid condensation reaction between them. This is beneficial for the directional formation of amide bonds (-NH-CO-). As amide bonds continue to form, more L-arginine is successfully grafted onto the resin. The grafting of L-arginine adds more active sites to the resin, enabling it to effectively bind with nickel ions, thus improving the resin's adsorption capacity for nickel ions. Detailed Implementation

[0012] Those skilled in the art should understand that these embodiments are merely for explaining the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0013] This patent discloses a method for preparing a modified ion exchange resin and its application. The specific method includes the following steps: D401 resin was selected as the raw material. Specifically, D401 resin is a chelated iminodiacetic acid macroporous styrene copolymer crosslinking polymer ion exchange resin. The resin was first dissolved in anhydrous ethanol and soaked for 6 hours to allow the resin to fully swell. Then, it was soaked in dilute hydrochloric acid with a concentration of 35g / L~55g / L for 2 hours to pretreat the resin to the hydrogen form, thus completing the resin pretreatment.

[0014] The resin swells in the ethanol system, allowing for a more complete reaction and full expansion of the resin skeleton. This prepares the resin for subsequent group grafting, facilitates better subsequent reactions, and allows for more accurate addition of target groups. It also enhances the subsequent adsorption of nickel ions.

[0015] The resin, EDC·HCl, and L-arginine were immersed in a solution system with a pH of 5 (the pH of the solution system was adjusted by 1% dilute hydrochloric acid) according to the specified ratio to obtain solution A. Solution A was heated to 35-45℃ and placed in a magnetic stirring pot. The stirring speed was set to 280-300 rpm, and the reaction was continued for 5-6 hours to obtain resin B and residual liquid B. Resin B was washed 5-6 times alternately with deionized water and anhydrous ethanol until the filtrate was neutral. Resin B was placed in a vacuum drying oven with a temperature of 55-60℃ and a vacuum degree of -0.09 MPa and dried until constant weight was obtained to obtain the modified ion exchange resin.

[0016] The carbodiimide in EDC·HCl used in this technology has strong electrophilic properties, which can activate the carboxyl groups at the ortho and para positions of the benzene ring in arginine to generate an oxyacylisourea intermediate. The amino group in L-arginine acts as a nucleophile, attacking the carbonyl carbon of the intermediate to form an amide bond. This exposes more coordinating active sites on the resin, which can then enhance the adsorption and selectivity of nickel ions through multiple coordination bonds. The nitrogen atom of the guanidino group has a lone pair of electrons that can form a strong coordination bond with nickel ions, and the amino group can help fix nickel ions through hydrogen bonding to enhance adsorption stability. This allows the original resin to obtain stronger adsorption and selectivity, and importantly, it improves both environmental friendliness and renewability.

[0017] In this technology, D401 resin, EDC·HCl, and L-arginine are mixed in a specific ratio and placed in a dilute hydrochloric acid solution at pH 5. During heating, the collision frequency of carboxyl and amino molecules increases significantly, thereby promoting the amino acid condensation reaction between them and facilitating the directional formation of amide bonds (-NH-CO-). As amide bonds continue to form, more L-arginine can be successfully grafted onto the resin. The grafting of L-arginine adds more active sites to the resin, enabling it to effectively bind with nickel ions, thus improving the resin's adsorption capacity for nickel ions.

[0018] The pH value of the system has a significant impact on the adsorption capacity of L-arginine-modified D401 resin for nickel ions. When the pH of the reaction system is <3, the adsorption capacity of L-arginine on the surface is significantly reduced. Due to protonation, it becomes The charged state of L-arginine, this protonated state, not only reduces the electron cloud density of the amino group, but also hinders the effective grafting of L-arginine to the carboxyl groups of the resin through electrostatic repulsion. This results in the modified resin's adsorption capacity not reaching the optimal state. As the pH gradually increases from 3 to 5, the deprotonation degree of the carboxyl groups on the resin surface increases, forming a group with stronger coordination ability. Anionic group. At the same time, the amino group remains in a moderately protonated state, which allows the amino and carboxyl groups to combine more stably to form an amide bond.

[0019] When the mass ratio of L-arginine to resin gradually increased from a relatively low 1:2 to 1:1, the adsorption capacity of the resin for nickel ions showed a significant increasing trend. With the increase in the amount of L-arginine added, the concentration of amino ligands in the reactants also increased. This increased concentration promoted a more effective grafting reaction between the amino groups and the carboxyl groups on the resin. Furthermore, this modification method may also improve the physicochemical properties of the resin, such as its specific surface area and porosity, thereby enhancing the resin's adsorption capacity.

[0020] When the mass ratio of L-arginine to resin exceeds 1:1, the adsorption capacity begins to decrease. The fundamental reason for this phenomenon is that excessive L-arginine leads to an overly high concentration of amino ligands in the reaction system. These excess amino ligands aggregate on the resin surface, creating a steric hindrance effect. This steric hindrance effect causes intermolecular or intramolecular spatial obstruction, limiting the effective contact and grafting reaction between the amino groups and the carboxyl groups in the resin. Furthermore, excessive L-arginine may also lead to over-occupancy of active sites on the resin surface, thereby reducing the resin's adsorption efficiency for nickel ions.

[0021] The modified resin showed significantly greater selectivity for nickel ions than the unmodified resin. Even in the presence of potassium, calcium, and magnesium ions, the modified resin maintained high selectivity for nickel ions (adsorption capacity >80%), attributed to the selectivity of the guanidine group for nickel ions. After five adsorption-desorption cycles, the adsorption capacity remained above 80% of the initial value, indicating good stability of the material. Dynamic adsorption-desorption experiments showed that the modified resin had better treatment capacity for actual electroless nickel plating wastewater compared to the unmodified resin.

[0022] When the pH of the solution reaches 5, the active sites on the resin surface can fully adsorb nickel ions. Under this pH condition, nickel exists stably in the solution mainly in ionic form. On the one hand, excessive acidity of the solution will not cause a large number of hydrogen ions to displace nickel ions, thus hindering the binding of nickel ions to the active sites of the resin; on the other hand, excessive alkalinity of the solution will not cause nickel ions to undergo hydrolysis and precipitation, thereby affecting the adsorption of nickel ions by the resin. Example 1

[0023] D401 resin was pretreated as described above. 10g of the pretreated resin, EDC·HCl, and L-arginine were weighed and mixed in a solution with a pH of 5. The mixture was placed in a reaction vessel, and the stirring speed was set to 280-300 rpm. The reaction was continued at 35-45℃ for 5-6 hours to obtain resin B and residual liquid. After filtration, resin B was washed 5-6 times alternately with deionized water and anhydrous ethanol until the filtrate was neutral. The obtained resin B was continuously dried at 55-60℃ and a vacuum of -0.09MPa until the resin morphology was stable and the color was uniform, thus obtaining the modified ion exchange resin.

[0024] The modified ion exchange resin obtained in Example 1 was added at a concentration of 1 g / L to simulated electroplating wastewater (initial nickel ion concentration of 100 ± 5 mg / L, pH of 5.0-6.0) for adsorption experiments. The adsorption experiment process is as follows: Simulated wastewater was placed in an Erlenmeyer flask and a constant-temperature magnetic stirring water bath was used. The temperature was set at 25℃ and the rotation speed at 150 rpm. The adsorption was carried out for 6 hours. After the adsorption experiment was completed, the adsorption degree of nickel ions by the modified ion exchange resin was tested. The nickel ion adsorption capacity was 81.93 mg / g.

[0025] The resin was regenerated by using a 5% hydrochloric acid solution as an eluent after adsorption. The modified ion exchange resin was subjected to multiple adsorption and regeneration cycles. After 5 cycles, the adsorption capacity of the regenerated resin was more than 80% of the initial value.

[0026] Comparative Example 1 Using unmodified D401 resin, i.e., the original D401 resin that has not undergone L-arginine grafting modification, its effect on [the following] was tested under the same reaction conditions as in Example 1. The adsorption performance and selectivity were tested, and the nickel ion adsorption capacity was 64.37 mg / g. Example 2

[0027] Based on Example 1, the reaction temperature was limited to 40°C, the ratio of the three raw materials was 2:3:2, the reaction time was 5.5 hours, and the stirring speed was 290 rpm to prepare the modified ion exchange resin described in Example 2.

[0028] The static adsorption test process is as follows: Three types of simulated wastewater were prepared respectively: ① pure Solution (initial concentration 100 mg / L, pH=5.0, 25℃); , , , Mixed solutions (initial mass ratio of ions 1:1:1:1, Initial concentration 100 mg / L, pH=5.0, 25℃); ③ Simulated nickel plating wastewater ( Concentration 98 mg / L, containing , , (pH=4.8, 25℃) Adsorption tests were conducted according to the test method of Example 1, and the test results are shown in the table below: Comparative Example 2 This experiment used unmodified D401 resin, i.e., the original D401 resin that has not undergone L-arginine grafting modification, and conducted adsorption experiments in the three simulated wastewaters described in Example 2 to test its adsorption capacity under the same reaction conditions as in Example 2. The adsorption performance and selectivity of the modified ion exchange resin were studied to verify its optimal adsorption capacity under optimal conditions. The high adsorption and selectivity of [the material / equipment]. The experimental results are shown in the table below: According to the table above, unmodified D401 resin has a significant effect on pure... The saturated adsorption capacity of the solution was only 64.37 mg / g, in the presence of , , In systems with coexisting ions, The adsorption capacity decreased significantly due to the presence of coexisting ions and Competing for active sites on the resin surface; simultaneously, unmodified D401 resin... , It has a high adsorption capacity and is effective against... The selectivity coefficients for all samples were below 10. The selectivity coefficient is even only around 4, indicating that it is only about 4. The selectivity is poor, making it impossible to achieve efficient selective adsorption and recovery of nickel ions.

[0029] In Example 2, the modified ion exchange resin... The adsorption capacity was significantly improved, and the modified resin showed improved adsorption capacity in pure... The adsorption capacity in solution reached 83.56 mg / g, an increase of 29.8% compared to unmodified D401 resin (64.37 mg / g), even in coexisting ion systems. The adsorption capacity remained above 78 mg / g, indicating that the modified resin... Its specific adsorption capacity has been greatly enhanced. The adsorption capacity is significantly reduced, and the selectivity is greatly improved: the resin in this embodiment has a significantly reduced adsorption capacity and a significantly improved selectivity. relatively The selectivity coefficient is above 14, relatively Reaching 18 or above, relatively The levels reached over 20%, more than twice that of unmodified resin. This is because the guanidinium and amide groups of L-arginine were successfully grafted onto the resin backbone, and the lone pair electrons of the nitrogen atom in the guanidinium group and... Strong coordination bonds are formed, and amino groups are fixed with the assistance of hydrogen bonds. This formed a consensus with The specific coordination site, and , , Unable to form stable coordination with guanidine groups, it can only adsorb in small amounts at non-specific sites on the resin surface, thus achieving... Efficient separation from coexisting ions. Example 3

[0030] The modified ion exchange resin prepared in Example 2 was used to prepare different... Static adsorption tests were conducted on simulated wastewater with initial concentrations (10~200 mg / L) to verify the adsorption performance of the resin at different nickel ion concentrations, further expanding the application range of the resin.

[0031] Test steps Simulated wastewater configurations: different Initial concentrations of pure solutions: 10, 50, 100, 150, 200 mg / L, pH=5.0, 25℃; Adsorption test: According to the static adsorption test method of the present invention, the resin dosage is 1 g / L, adsorption is carried out for 6 hours until adsorption equilibrium is reached, and the adsorption amount of each ion is measured.

[0032] The adsorption test results for different initial nickel ion concentrations are shown in the table below: Wide range of Ni 2+ Initial concentration: Modified resin to Solutions with initial concentrations of 10–200 mg / L all exhibited high adsorption performance. At low concentrations (10–50 mg / L), the adsorption rate reached over 98%, achieving near-complete removal of nickel ions. At high concentrations (150–200 mg / L), the adsorption capacity remained above 120 mg / g.

[0033] Based on the test results of the above embodiments and comparative examples, the modified ion exchange resin of the present invention has a wide range of applicability in the adsorption and recovery of nickel ions in industrial nickel plating wastewater. The specific applicable scenarios and the basis for demonstration are as follows. At the same time, the preparation method of this resin is simple, the raw materials are readily available, and the regeneration performance is excellent, which meets the technical and economic requirements for industrial-scale application.

[0034] Although the invention has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0035] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a modified ion exchange resin, characterized in that: The method includes the following steps: (1) Dissolve D401 resin in ethanol and soak for 6 hours. Then pretreat the resin with dilute hydrochloric acid to the hydrogen form to fully expand the resin skeleton and make more adequate preparation for subsequent group grafting. Then weigh D401 resin, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and L-arginine according to the proportion and soak them in a solution system with pH 5±0.2 to obtain solution A. (2) Heat the mixed solution A to 35-45℃ and stir at 280-300 rpm for 5-6 hours to obtain resin B and residual liquid B. Filter the residual liquid B and wash the resin B with deionized water and ethanol alternately 5-6 times until the filtrate is neutral. (3) Resin B was dried continuously at 55-60℃ and vacuum degree -0.09MPa until constant weight to obtain modified ion exchange resin.

2. The method for preparing a modified ion exchange resin according to claim 1, characterized in that: The D401 resin is specifically a chelated iminodiacetic acid macroporous styrene copolymer crosslinked polymer ion exchange resin.

3. The method for preparing a modified ion exchange resin according to claim 1, characterized in that: During the pretreatment of D401 resin, it is soaked in dilute hydrochloric acid with a concentration of 35g / L-55g / L for 2 hours.

4. The method for preparing a modified ion exchange resin according to claim 1, characterized in that: The mass-volume ratio of the D401 resin to EDC·HCl and L-arginine is (1-2):1.5:

1.

5. The method for preparing a modified ion exchange resin according to claim 1, characterized in that: The solution system with a pH of 5 ± 0.2 was obtained by adjusting the pH with dilute hydrochloric acid solution.

6. The method for preparing a modified ion exchange resin according to claim 1, characterized in that: The specific conditions for the drying process are: at a temperature of 55-60℃, the vacuum degree is maintained at around -0.09MPa, and the drying time is not less than 6 hours, until the resin is dried to a stable state and uniform color.

7. The method for preparing a modified ion exchange resin according to claim 1, characterized in that: The ethanol used in the preparation method is anhydrous ethanol.

8. Application of a modified ion exchange resin in adsorbing nickel ions in nickel plating wastewater.

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