Polymer resin for removing metal impurities in cyanide-free electroplating cadmium solution as well as preparation method and use method of polymer resin

Abstract

The invention discloses polymer resin for removing metal impurities in a cyanide-free electroplating cadmium solution as well as a preparation method and a use method of the polymer resin, and relates to the technical field of functional materials. The invention relates to a polymer resin for removing metal impurities in a cyanide-free electroplating cadmium solution. The polymer resin comprises a polymer matrix, cyclodextrin covalently crosslinked to the polymer matrix and a functionalized functional group for functionally modifying the polymer matrix, the functionalized functional group comprises an iminodiacetic acid group, a sulfydryl group and an amido group. According to the invention, cyclodextrin is introduced into a polymer matrix through covalent cross-linking, then three functional groups with high metal affinity are used for modification, and through the inclusion effect of cyclodextrin and the targeted collaborative design of the three functional groups, the ability of polymer resin to selectively capture metal impurities is enhanced; even in the environment of competing with EDTA, NTA and other strong chelating agents, the metal impurities can still be effectively combined and removed by breaking the competition barrier.

Description

Technical Field

[0001] The present application relates to the technical field of functional materials, and in particular to a polymer resin for removing metal impurities in a cyanide-free cadmium electroplating solution, and a preparation method and a use method thereof. Background Art

[0002] Electroplating cadmium is widely used in aerospace, shipbuilding and precision instrument fields due to its high corrosion resistance. 2+ 、Fe 3+ 、Ni 2+ , Pb 2+ and Cr 3+ The presence of metal impurities such as ions will cause defects such as pores, nodules and decreased adhesion in the coating, which will seriously reduce the durability of the product. In order to remove these metal impurities, conventional methods are to use low-current electrolysis, add masking agents or use adsorption resins for adsorption. However, the problem with low-current electrolysis is that it cannot remove all metals. It can only remove some easily reducible metals (such as Cu 2+ ), for Fe 3+ Cr 3+ The removal rate of the like is less than 50%; the addition of masking agents can only complex metal impurity ions to inhibit co-deposition, but does not remove metal impurity ions. Long-term accumulation will lead to the failure of the plating solution; although the use of adsorption resin can remove metal impurities without polluting the plating solution, the adsorption efficiency is not high, and although the cyanide-free process is environmentally friendly, it relies on strong chelating agents such as ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) to stabilize cadmium ions. These chelating agents also form stable complexes with metal impurities (such as EDTA-Fe with a stability constant of 10 25 ), resulting in the inability of traditional adsorption resins to competitively bind impurity metals. Based on this, the present application proposes a polymer resin that can selectively remove metal impurities from cyanide-free cadmium plating solutions. Summary of the Invention

[0003] The main purpose of this application is to provide a polymer resin for removing metal impurities in cyanide-free cadmium plating solution, and its preparation method and use method, aiming to solve the technical problem that existing methods cannot effectively remove metal impurities in cyanide-free cadmium plating solution.

[0004] To achieve the above objectives, the present application proposes a polymer resin for removing metal impurities in a cyanide-free cadmium electroplating solution, the polymer resin comprising: A polymer matrix, a cyclodextrin covalently cross-linked to the polymer matrix, and a functional group for functionally modifying the polymer matrix; The functional groups include iminodiacetic acid groups, thiol groups and amine groups.

[0005] Optionally, the polymer matrix is one of polyacrylamide, polyethylene glycol diacrylate and polyvinyl alcohol; the cyclodextrin is β-cyclodextrin, and the cyclodextrin is covalently cross-linked to the polymer matrix through epichlorohydrin.

[0006] Optionally, the molar ratio of the iminodiacetic acid group, the thiol group and the amine group is (3-5): (1.5-2.5): (2.5-4); and the mass ratio of the cyclodextrin to the polymer matrix is 1: (1.5-3.0).

[0007] The present application also proposes a method for preparing a polymer resin for removing metal impurities in a cyanide-free cadmium electroplating solution, comprising the following steps: Synthesis of polymer matrix by free radical polymerization; Introducing iminodiacetic acid groups, thiol groups and amine groups into the polymer matrix for functional modification to obtain a functionalized polymer; covalently cross-linking cyclodextrin to the functionalized polymer to form a three-dimensional network structure to obtain a resin mixture; The resin mixture is precipitated, washed and dried to obtain a polymer resin.

[0008] Optionally, the step of synthesizing the polymer matrix by free radical polymerization comprises: Dissolve the polymerization monomer in a solvent, add the initiator and catalyst under a nitrogen atmosphere, stir at room temperature for 0.5h-4h, then heat to 55℃-65℃ and stir for 1h-5h to complete the free radical polymerization reaction; Wherein, the polymerizable monomer is one of acrylamide, polyethylene glycol diacrylate monomer and polyvinyl alcohol monomer; The initiator is ammonium persulfate or azobisisobutyronitrile; The catalyst is N,N,N',N'-tetramethylethylenediamine.

[0009] Optionally, the step of introducing iminodiacetic acid groups, thiol groups and amine groups into the polymer matrix for functional modification to obtain a functionalized polymer comprises: During or after the free radical polymerization reaction of the polymer matrix, adding a functional monomer and reacting at 55° C.-65° C. for 1 h-5 h to graft the functional groups into the polymer matrix to obtain a functionalized polymer; The functional monomers include iminodiacetic acid functionalized acrylamide, mercapto-modified acrylamide and amine-functionalized acrylamide.

[0010] Optionally, the step of covalently cross-linking cyclodextrin to the functionalized polymer to form a three-dimensional network structure to obtain a resin mixture comprises: dissolving cyclodextrin in a solvent to obtain a cyclodextrin solution; Add epichlorohydrin to the cyclodextrin solution, and stir at room temperature for 25 min to 35 min to obtain a mixed solution; The mixed solution is added to the functionalized polymer, and the mixture is stirred and reacted at 50° C.-60° C. for 2 h-3 h to covalently crosslink the cyclodextrin to the functionalized polymer, thereby obtaining a resin mixed solution.

[0011] Optionally, the step of obtaining a polymer resin by precipitating, washing and drying the resin mixture comprises: After the resin mixture is cooled, acetone is added for precipitation, and a polymer solid is obtained by filtration. The polymer solid is then washed 3-4 times with ethanol and then vacuum-dried at 40-50° C. for 24-48 hours to obtain a polymer resin.

[0012] The present application also proposes a method for using a polymer resin to remove metal impurities in a cyanide-free cadmium electroplating solution, comprising the following steps: activating the polymer resin with a weak acid solution, and then washing with water until neutral, to obtain an activated polymer resin; contacting the activated polymer resin with a cadmium electroplating solution to adsorb metal impurities, while periodically sampling the cadmium electroplating solution to monitor the concentration of the metal impurities; After the adsorption is completed, the activated polymer resin is washed, desorbed and neutralized to regenerate the activated polymer resin into a saturated resin.

[0013] Optionally, the step of contacting the activated polymer resin with a cadmium electroplating solution to adsorb metal impurities comprises: The activated polymer resin is loaded into an adsorption column, and the electroplating cadmium solution is controlled to circulate through the adsorption column at a flow rate of 1BV / h-5BV / h to adsorb metal impurities.

[0014] Optionally, the step of contacting the activated polymer resin with a cadmium electroplating solution to adsorb metal impurities comprises: The activated polymer resin is added to the electroplating tank and stirred for 1-2 hours to allow the activated polymer resin to contact the electroplating cadmium solution to adsorb metal impurities.

[0015] Optionally, the steps of flushing, desorbing and neutralizing the activated polymer resin include: After rinsing the activated polymer resin with deionized water, desorption is performed with a 0.5M-1M hydrochloric acid solution for 1 hour to 2 hours, and then rinsed with deionized water. Then, the resin is neutralized with a 0.5M-1M alkaline solution and then rinsed with deionized water until neutral.

[0016] This application has at least the following beneficial effects: This application designs three functional groups with high metal affinity, including iminodiacetic acid group, thiol group and amine group. The iminodiacetic acid group can preferentially capture transition metals through bidentate chelation. 3+ 、Ni 2+ The binding constant of metals such as EDTA and NTA is greater than that of EDTA and NTA, while the thiol group can bind to Cu 2+ , Pb 2+ etc. to form covalent bonds, thereby specifically adsorbing heavy metals. The amine group has a broad spectrum of ion exchange properties and can be protonated (-NH3 + ) adsorbs anionic impurities, thereby covering multiple types of metal impurities. Through the targeted collaborative design of three functional groups, the polymer resin can be provided with a stronger metal impurity binding ability. Even in an environment where it competes with strong chelating agents such as EDTA and NTA, it can still break through the competitive barriers and effectively bind and remove metal impurities such as copper, iron and nickel. This selective removal ensures that only unwanted metal ions are captured, while the necessary cadmium ions remain in the solution; The present application introduces cyclodextrin into a polymer matrix through covalent cross-linking. The cyclodextrin has a hydrophobic cavity that can enclose metal-EDTA, metal-NTA, and other complexes to form inclusion compounds. Under the inclusion action, the coordination bonds of EDTA and NTA are destroyed, exposing free metal ions to the range of action of the functional groups of the polymer resin, thereby enhancing the ability of the polymer resin to selectively capture metal impurities and improving its efficiency in removing metal impurities in the presence of strong chelating agents such as EDTA and NTA. The polymer resin of the present application is reversibly regenerable. Acid desorption can destroy the coordination bond between the metal and functionalized functional groups without damaging the covalent cross-linked skeleton, while alkali neutralization can restore the protonation ability of the amine group. After multiple regenerations, it still has an excellent adsorption rate, thereby reducing the replacement frequency of the polymer resin and lowering operating costs. The polymer resin of the present application can form a three-dimensional stable network after cross-linking with cyclodextrin, thereby improving its stability and being adaptable to the operating conditions of various cadmium electroplating solutions. Even under different pH values and temperature conditions, the polymer resin can effectively remove metal impurities and ensure the purity of the cadmium electroplating solution and the quality of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0018] Figure 1 This is a flow chart of the preparation method of the polymer resin described in the examples of this application; Figure 2 This is a flow chart of the method for using the polymer resin described in the embodiments of the present application.

[0019] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0021] In view of the technical problems existing in the prior art, an embodiment of the present application provides a polymer resin for removing metal impurities in a cyanide-free cadmium electroplating solution, wherein the polymer resin comprises: A polymer matrix, a cyclodextrin covalently cross-linked to the polymer matrix, and a functional group for functionally modifying the polymer matrix; The functional groups include iminodiacetic acid groups, thiol groups and amine groups.

[0022] In this application, cyclodextrin is introduced into a polymer matrix through covalent cross-linking, and then modified with three functional groups with high metal affinity. Cyclodextrin has a hydrophobic cavity, which can include metal-EDTA, metal-NTA and other complexes to form inclusion compounds. Under the inclusion action, the coordination bonds of EDTA and NTA can be destroyed, exposing free metal ions. At the same time, the iminodiacetic acid group preferentially captures transition metals through bidentate chelation. 3+ 、Ni 2+ The binding constant of metals such as EDTA and NTA is greater than that of EDTA and NTA, while the thiol group can bind to Cu 2+ , Pb 2+ etc. to form covalent bonds, thereby specifically adsorbing heavy metals. The amine group has a broad spectrum of ion exchange properties and can be protonated (-NH3 +) adsorbs anionic impurities and covers multiple types of metal impurities. Through the inclusion effect of cyclodextrin and the targeted collaborative design of three functional groups, it not only enhances the ability of polymer resin to selectively capture metal impurities, but also provides polymer resin with stronger metal impurity binding ability. Even in an environment competing with strong chelating agents such as EDTA and NTA, it can still break through the competitive barriers and effectively bind and remove metal impurities. This selective removal ensures that only unnecessary metal ions are captured, while the necessary cadmium ions remain in the solution. By eliminating metal impurities that may interfere with the electroplating process, it helps to produce more uniform, durable and corrosion-resistant cadmium coatings.

[0023] As an implementation method of the present application, the polymer matrix is one of polyacrylamide, polyethylene glycol diacrylate and polyvinyl alcohol; the cyclodextrin is β-cyclodextrin, and the cyclodextrin is covalently cross-linked to the polymer matrix through epichlorohydrin.

[0024] This application uses easily modified polyacrylamide, polyethylene glycol diacrylate and polyvinyl alcohol as polymer matrices. As polar main chains, they can provide abundant grafting sites, have high functionalization capacity, and can provide polymer structural integrity and high surface area functionalization for the polymer resin.

[0025] Specifically, the cavity size of β-cyclodextrin is 0.65nm-0.78nm, and β-cyclodextrin is preferably mono-6-deoxy-6-amino-β-cyclodextrin, which can encapsulate the hydrophobic group (-CH2-) of EDTA through hydrophobic interaction, and the inclusion complex can distort the conformation of EDTA, thereby causing M + -O / N coordination bond angle deviates, bond energy decreases, and the weakened coordination bond breaks under thermal motion, making the free metal ion (M + ) exposes the scope of functional groups of the polymer resin, thereby enhancing the ability of the polymer resin to selectively capture metal impurities and improving its effectiveness in the presence of strong chelating agents.

[0026] As an embodiment of the present application, the molar ratio of the iminodiacetic acid group, the thiol group and the amine group is (3-5): (1.5-2.5): (2.5-4); the mass ratio of the cyclodextrin to the polymer matrix is 1: (1.5-3.0).

[0027] This application optimizes the ratio of the three functional groups of iminodiacetic acid group, thiol group and amine group, as well as the ratio of cyclodextrin to polymer matrix, to ensure that the polymer resin has sufficient cross-linking density and the three functional groups are evenly grafted to avoid local saturation, so that the polymer resin can stably bind Fe 3+ 、Ni 2+ 、Cu 2+, Pb 2+ And many other metal impurity ions.

[0028] The embodiments of the present application also provide a method for preparing a polymer resin for removing metal impurities in a cyanide-free cadmium plating solution, such as Figure 1 As shown, the following steps are included: S10. Synthesizing a polymer matrix through free radical polymerization.

[0029] In a specific implementation process, the polymerization monomer is dissolved in a solvent, which is water or ethanol. An initiator and a catalyst are added under a nitrogen atmosphere. After stirring at room temperature for 0.5-4 hours, the temperature is raised to 55-65° C. and stirred for 1-5 hours to complete the free radical polymerization reaction. Wherein, the polymerizable monomer is one of acrylamide, polyethylene glycol diacrylate monomer and polyvinyl alcohol monomer; The initiator is ammonium persulfate or azobisisobutyronitrile; The catalyst is N,N,N',N'-tetramethylethylenediamine.

[0030] This application uses ammonium persulfate or azobisisobutyronitrile as an initiator and N,N,N',N'-tetramethylethylenediamine as a catalyst to initiate a free radical polymerization reaction of the polymerization monomer to synthesize a polymer matrix and provide sufficient chain length and cross-linking points for subsequent covalent cross-linking of cyclodextrin.

[0031] S11, introducing iminodiacetic acid groups, thiol groups and amine groups into the polymer matrix for functional modification to obtain a functionalized polymer.

[0032] In a specific implementation process, during or after the free radical polymerization reaction of the polymer matrix, a functional monomer is added and reacted at 55° C.-65° C. for 1 h-5 h to graft the functional group into the polymer matrix to obtain a functional polymer; The functional monomers include iminodiacetic acid functionalized acrylamide, mercapto-modified acrylamide and amine-functionalized acrylamide.

[0033] Iminodiacetic acid functionalized acrylamide can use N-(2-carboxyethyl)iminodiacetic acid, which has an iminodiacetic acid group and preferentially captures transition metals mainly through bidentate chelation. It can compete with EDTA and NTA and provide stronger metal impurity binding ability. Mercapto-modified acrylamide can use 2-mercaptoethyl acrylate, which has a mercapto group and can bind the main heavy metal Cu in the electroplating cadmium solution. 2+ , Pb 2+Amine-functionalized acrylamide uses acrylamide with primary amine groups. The amine groups provide broad-spectrum ion exchange capabilities, enabling the polymer resin to capture a variety of metal impurities. By incorporating functionalized monomers during or after polymerization, the polymer matrix is functionalized, resulting in a high density of active sites, ensuring maximum interaction with metal impurities. S12, covalently cross-linking the cyclodextrin to the functionalized polymer to form a three-dimensional network structure to obtain a resin mixture.

[0034] In a specific implementation process, cyclodextrin is dissolved in a solvent to obtain a cyclodextrin solution; Add epichlorohydrin to the cyclodextrin solution, and stir at room temperature for 25 min to 35 min to obtain a mixed solution; The mixed solution is added to the functionalized polymer, and the mixture is stirred and reacted at 50° C.-60° C. for 2 h-3 h to covalently crosslink the cyclodextrin to the functionalized polymer, thereby obtaining a resin mixed solution.

[0035] Specifically, cyclodextrin is covalently bonded to the polymer through epichlorohydrin rather than physical doping, which can enable the polymer resin to form a rigid network to improve the stability of the polymer resin. Even under various electroplating conditions, the plating solution has different pH values and temperatures, the polymer resin can stably remove metal impurities. The inclusion complexation of cyclodextrin can create a microenvironment in the polymer matrix that is conducive to the capture of specific ions, allowing the polymer resin to form a three-dimensional network structure with active sites for metal ion capture, thereby enhancing the ability of the polymer resin to selectively capture metal impurities.

[0036] S13, precipitating, washing and drying the resin mixture to obtain a polymer resin.

[0037] In a specific implementation process, the resin mixture is cooled, added into acetone for precipitation, filtered to obtain a polymer solid, then washed 3-4 times with ethanol, and then vacuum dried at 40-50° C. for 24-48 hours to obtain a polymer resin.

[0038] The embodiments of the present application also provide a method for using a polymer resin to remove metal impurities in a cyanide-free cadmium plating solution, such as Figure 2 As shown, the following steps are included: S20, activating the polymer resin with a weak acid solution, and then washing with water until neutral, to obtain an activated polymer resin.

[0039] Specifically, the polymer resin needs to be activated before use, and can be washed with 0.1 M hydrochloric acid to ensure that the functional groups are in ionic form, and then the polymer resin is thoroughly rinsed with deionized water to remove residual acid.

[0040] S21, contacting the activated polymer resin with a cadmium electroplating solution to adsorb metal impurities, and periodically sampling the cadmium electroplating solution to monitor the concentration of the metal impurities.

[0041] During the specific implementation process, the activated polymer resin can be integrated into the electroplating tank through an adsorption column. The size of the adsorption column can be selected according to the volume of the electroplating tank and the flow rate that allows the solution to fully contact the resin. The activated polymer resin is loaded into the adsorption column, and the adsorption column is connected to the circulation system. The electroplating cadmium solution is controlled to circulate through the adsorption column at a flow rate of 1BV / h-5BV / h to ensure that the metal impurities have enough time to be adsorbed by the polymer resin.

[0042] In a specific implementation process, the activated polymer resin can be directly added to the electroplating tank and continuously stirred for 1 hour to 2 hours to allow the activated polymer resin to fully contact with the electroplating cadmium solution to adsorb metal impurities.

[0043] Specifically, during the adsorption process, the concentration of metal impurities can be monitored by analytical techniques such as atomic absorption spectroscopy (AAS) or inductively coupled plasma mass spectrometry (ICP-MS) until the impurity concentration is reduced to the desired level.

[0044] S22, after the adsorption is completed, the activated polymer resin is rinsed, desorbed and neutralized to regenerate the activated polymer resin into a saturated resin.

[0045] In the specific implementation process, the activated polymer resin is first rinsed with deionized water to remove residual electroplating solution, which helps prevent the formation of precipitates and prepares for an effective desorption process. The activated polymer resin is then desorbed with a 0.5M-1M hydrochloric acid solution for 1h-2h to ensure that the hydrochloric acid solution is in full contact with the polymer resin. The desorbed solution is tested for metal ion concentration to confirm that most of the impurities on the polymer resin have been removed. The activated polymer resin is then rinsed with deionized water to remove residual acid, and then neutralized with a 0.5M-1M sodium hydroxide or sodium bicarbonate solution. The resin is then rinsed with deionized water until neutral, thereby regenerating it into a saturated resin.

[0046] To ensure that the functional groups on the polymer resin are in the optimal ionic state, the polymer resin can be further immersed in a dilute acid (such as 0.1 M acetic acid) and then rinsed with deionized water. This helps to restore the functional groups of the polymer resin (such as iminodiacetic acid) to an active state, ensuring that it can effectively adsorb metal ions in the next cycle.

[0047] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0048] Example 1 Preparation and Application of Polyacrylamide-Based Resin Preparation steps: Step 1. Prepare materials and reagents Acrylamide (main chain polymerization monomer): 500g; Iminodiacetic acid functionalized acrylamide (using N-(2-carboxyethyl)iminodiacetic acid): 125g; Mercapto-modified acrylamide (using 2-mercaptoethyl acrylate): 75g; Amine-functionalized acrylamide (acrylamide with primary amine groups): 125g; Cyclodextrin (mono-6-deoxy-6-amino-β-cyclodextrin): 250g; Cross-linking agent (epichlorohydrin): 125g; Solvents: water, dimethyl sulfoxide (DMSO), acetone, ethanol; Initiator (ammonium persulfate): 10g; Catalyst (N,N,N',N'-tetramethylethylenediamine, TEMED): 10 g.

[0049] Step 2: Polymerization Prepare a 3-5 L reactor equipped with a mechanical stirrer and purged with nitrogen to maintain an inert atmosphere. Add 2 L of deionized water to the reactor and dissolve acrylamide in the deionized water. Then add the iminodiacetic acid-functionalized acrylamide, thiol-modified acrylamide, and amine-functionalized acrylamide. Stir at room temperature for 1 h to ensure that all monomers are completely dissolved to obtain a monomer solution. If not completely dissolved, add 100 mL of DMSO to improve solubility. Under nitrogen atmosphere, ammonium persulfate and TEMED were added to the monomer solution to initiate a free radical polymerization reaction, and the mixture was stirred at room temperature for 3 h. The temperature was then gradually raised to 60°C and stirred for another 1 h to complete the polymerization, thereby obtaining a functionalized polymer. During the polymerization process, check the progress of the polymerization reaction by monitoring the viscosity of the solution; the solution should gradually thicken as the polymer chains are formed.

[0050] Step 3: Cross-linking with cyclodextrin Dissolve mono-6-deoxy-6-amino-β-cyclodextrin in 500 mL of water, add epichlorohydrin, and stir at room temperature for 30 minutes to obtain a mixed solution; The mixture was added to the functionalized polymer under continuous stirring, heated to 50°C, and kept stirring for 2 hours. During this period, epichlorohydrin acted as a cross-linking agent to bind cyclodextrin to the polymer backbone to obtain a resin mixture. During the cross-linking process, the viscosity and gelation process of the solution were monitored to confirm the progress of cross-linking.

[0051] Step 4: Precipitation and purification After the cross-linking reaction is completed, the resin mixture is cooled to room temperature; Under vigorous stirring, the resin mixture was added to 10 L of acetone. The polymer was precipitated as a solid and filtered using a Buchner funnel to obtain a polymer solid. The polymer solid was washed three times with ethanol to remove unreacted monomers, cyclodextrin and cross-linking agent residues, and then vacuum dried at 40°C for 36 hours until constant weight was reached to obtain a cross-linked polyacrylamide resin containing iminodiacetic acid, thiol and amine functional groups.

[0052] application: The cross-linked polyacrylamide resin was washed with 0.1M hydrochloric acid and then rinsed with deionized water until neutral to remove residual acid, thereby obtaining an activated polymer resin; The activated polymer resin is loaded into the adsorption column, and the adsorption column is connected to the circulation system to control the content of 5ppm Fe 3+ , 3ppm Cu 2+ The electroplating cadmium solution (pH 6.5) was circulated through the activated polymer resin at a flow rate of 3BV / h to ensure that the metal impurities had enough time to be adsorbed. At the same time, samples were taken from the electroplating cadmium solution regularly and the concentration of metal impurities was detected by atomic absorption spectrometry. The metal impurity ion concentration after 2 hours is shown in Table 1 below.

[0053] Table 1

[0054] As can be seen from Table 1, the polymer resin in this embodiment can achieve Fe 3+ and Cu 2+ The effective adsorption and removal rate are all above 98%.

[0055] Regeneration: After adsorption, the polymer resin was rinsed with deionized water to remove the residual electroplating cadmium solution, and then desorbed with 0.8M hydrochloric acid solution for 1 hour, and the metal ion concentration was tested to confirm that most of the impurities on the polymer resin had been removed. The polymer resin was then rinsed with deionized water to remove the residual acid, and then neutralized with 0.8M sodium hydroxide, and then rinsed with deionized water until neutral, thereby regenerating into a saturated resin.

[0056] Example 2 Preparation and Application of Polyethylene Glycol Diacrylate-Based Resin Preparation steps: Step 1. Prepare materials and reagents Polyethylene glycol diacrylate (molecular weight about 4000g / mol-6000g / mol, as the main chain): 1000g; Iminodiacetic acid functionalized acrylamide (using N-(2-carboxyethyl)iminodiacetic acid): 200g; Mercapto-modified acrylamide (using 2-mercaptoethyl acrylate): 120g; Amine-functionalized acrylamide (acrylamide with primary amine groups): 150g; Cyclodextrin (mono-6-deoxy-6-amino-β-cyclodextrin): 300g; Cross-linking agent (epichlorohydrin): 150g; Solvents: water, acetone, ethanol; Initiator (azobisisobutyronitrile, AIBN): 20g.

[0057] Step 2: Polymerization Prepare a 3L-5L reactor equipped with a mechanical stirrer and purged with nitrogen to maintain an inert atmosphere. Add 1.5L of ethanol to the reactor and dissolve polyethylene glycol diacrylate in the ethanol under continuous stirring to ensure that the polyethylene glycol diacrylate is completely dissolved and a homogeneous solution is formed. Slowly add iminodiacetic acid functionalized acrylamide, thiol-modified acrylamide, and amine-functionalized acrylamide. Stir at room temperature for 0.5h to ensure that all monomers are evenly mixed to obtain a monomer solution. Under a nitrogen atmosphere, azobisisobutyronitrile was added to the monomer solution and stirred, and then the temperature was raised to 60°C, kept warm and stirred for 4 hours to initiate a free radical polymerization reaction to obtain a functionalized polymer; During the polymerization process, the progress of the polymerization reaction was checked by monitoring the viscosity of the solution, which gradually formed a viscous solution as the polymer chains formed.

[0058] Step 3: Cross-linking with cyclodextrin Dissolve mono-6-deoxy-6-amino-β-cyclodextrin in 1 L of water. After complete dissolution, add epichlorohydrin and stir at room temperature for 30 minutes to obtain a mixed solution. Under continuous stirring, the mixed solution was slowly added to the functionalized polymer, heated to 50°C, and kept stirring for 3 hours. During this period, epichlorohydrin promoted the formation of covalent bonds between cyclodextrin and the polymer backbone, forming a cross-linked network to obtain a resin mixed solution; During the cross-linking process, the viscosity and gelation process of the solution were monitored to confirm the progress of cross-linking.

[0059] Step 4: Precipitation and purification After the cross-linking reaction is completed, the resin mixture is cooled to room temperature; Under vigorous stirring, the resin mixture was added to 10 L of acetone. The polymer was precipitated as a solid and filtered using a Buchner funnel to obtain a polymer solid. The polymer solid was washed four times with ethanol to remove unreacted monomers, cyclodextrin and cross-linking agent residues, and then dried in vacuum at 40°C for 48 h until constant weight was reached to obtain a cross-linked polyethylene glycol diacrylate resin containing iminodiacetic acid, thiol and amine functional groups.

[0060] application: The cross-linked polyethylene glycol diacrylate resin was washed with 0.1 M hydrochloric acid and then rinsed with deionized water until neutral to remove residual acid, thereby obtaining an activated polymer resin; The activated polymer resin was added directly to the plating tank at a dosage of 3 g / L and mixed with 10 ppm Ni 2+ , 5g / LEDTA electroplating cadmium solution (pH 3) and continued stirring for 1.5h to allow the activated polymer resin to fully adsorb the metal impurities in the electroplating cadmium solution. At the same time, samples were taken from the electroplating cadmium solution regularly, and the concentration of metal impurities was detected by inductively coupled plasma mass spectrometry. The metal impurity ion concentration after 2h is shown in Table 2 below.

[0061] Table 2

[0062] As can be seen from Table 2, the polymer resin of this embodiment can also effectively adsorb Ni in an acidic environment. 2+ , which is good for you 2+ The removal rate can reach 98.8%.

[0063] Regeneration: After adsorption, the polymer resin was rinsed with deionized water to remove the residual electroplating cadmium solution, and then desorbed with 0.5M hydrochloric acid solution for 1 hour, and the metal ion concentration was tested to confirm that most of the impurities on the polymer resin had been removed. The polymer resin was then rinsed with deionized water to remove the residual acid, and then neutralized with 0.5M sodium hydroxide, and then rinsed with deionized water until neutral, thereby regenerating into a saturated resin.

[0064] Example 3 Preparation and Application of Polyvinyl Alcohol-Based Resin Preparation steps: Step 1. Prepare materials and reagents Polyvinyl alcohol (molecular weight about 70,000 g / mol-100,000 g / mol, as main chain): 1000 g; Iminodiacetic acid functionalized acrylamide (using N-(2-carboxyethyl)iminodiacetate): 150g; Mercapto-modified acrylamide (using 2-mercaptoethyl acrylate): 100g; Amine-functionalized acrylamide (acrylamide with primary amine groups): 100g; Cyclodextrin (mono-6-deoxy-6-amino-β-cyclodextrin): 300g; Cross-linking agent (epichlorohydrin): 200g; Solvents: water, acetone, ethanol; Initiator (ammonium persulfate): 20g; Catalyst (N,N,N',N'-tetramethylethylenediamine, TEMED): 10 g.

[0065] Step 2: Polymerization Prepare a 3L-5L reactor equipped with a mechanical stirrer and purged with nitrogen to maintain an inert atmosphere. Add 3L of deionized water to the reactor, dissolve the polyvinyl alcohol in the deionized water, heat to 80°C, and stir for 1 hour until the polyvinyl alcohol is completely dissolved. Then, the iminodiacetic acid functionalized acrylamide, the thiol-modified acrylamide and the amine functionalized acrylamide were dissolved in 300 mL of water to obtain a functionalized monomer mixture; The functionalized monomer mixture was slowly added to the polyvinyl alcohol aqueous solution under stirring, and the stirring was continued at 60°C for 1 hour to ensure uniform mixing. Ammonium persulfate and TEMED were then added to initiate a free radical polymerization reaction, and the mixture was stirred at 60°C for 3 hours to obtain a functionalized polymer. During the polymerization process, check the progress of the polymerization reaction by monitoring the viscosity of the solution; the solution should gradually thicken as the polymer chains are formed.

[0066] Step 3: Cross-linking with cyclodextrin Dissolve mono-6-deoxy-6-amino-β-cyclodextrin in 500 mL of water, add epichlorohydrin, and stir at room temperature for 30 minutes to obtain a mixed solution; The mixture was added to the functionalized polymer under continuous stirring, heated to 60°C, and kept stirring for 2 hours. During this period, epichlorohydrin acted as a cross-linking agent to bind cyclodextrin to the polymer backbone to obtain a resin mixture. During the cross-linking process, the viscosity and gelation process of the solution were monitored to confirm the progress of cross-linking.

[0067] Step 4: Precipitation and purification After the cross-linking reaction is completed, the resin mixture is cooled to room temperature; Under vigorous stirring, the resin mixture was added to 10 L of acetone. The polymer was precipitated as a solid and filtered using a Buchner funnel to obtain a polymer solid. The polymer solid was washed three times with ethanol to remove unreacted monomers, cyclodextrin and cross-linking agent residues, and then vacuum dried at 40°C for 24 hours until constant weight was reached to obtain a cross-linked polyvinyl alcohol resin containing iminodiacetic acid, thiol and amine functional groups.

[0068] application: The cross-linked polyvinyl alcohol resin was washed with 0.1M hydrochloric acid and then rinsed with deionized water until neutral to remove residual acid, thereby obtaining an activated polymer resin; The activated polymer resin was loaded into the adsorption column, and the adsorption column was connected to the circulation system to control the concentration of 8ppm Pb 2+ The electroplating cadmium solution (pH 8.0) was circulated through the activated polymer resin at a flow rate of 2 BV / h to ensure that the metal impurities had enough time to be adsorbed. At the same time, samples were taken from the electroplating cadmium solution regularly, and the concentration of metal impurities was detected by atomic absorption spectrometry. The concentrations of metal impurity ions were recorded after 10 minutes, 30 minutes, and 60 minutes of treatment, as shown in Table 3 below.

[0069] Table 3

[0070] As can be seen from Table 3, the polymer resin of this embodiment can quickly absorb Pb in the cadmium electroplating solution. 2+ , and after 60min Pb 2+ The concentration decreased significantly.

[0071] Regeneration: After adsorption, the polymer resin was rinsed with deionized water to remove the residual electroplating cadmium solution, and then desorbed with a 1M hydrochloric acid solution for 1 hour, and a metal ion concentration test was performed to confirm that most of the impurities on the polymer resin had been removed. The polymer resin was then rinsed with deionized water to remove residual acid, and then neutralized with 1M sodium hydroxide, and then rinsed with deionized water until neutral, thereby regenerating into a saturated resin.

[0072] The above description is merely an optional embodiment of the present application and does not limit the patent scope of the present application. All equivalent structural transformations made using the contents of the present application specification and drawings under the inventive concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A polymer resin for removing metal impurities in a cyanide-free cadmium plating solution, characterized in that: The polymer resin comprises: A polymer matrix, a cyclodextrin covalently cross-linked to the polymer matrix, and a functionalized functional group for functionally modifying the polymer matrix; the polymer matrix is one of polyacrylamide, polyethylene glycol diacrylate, and polyvinyl alcohol; the cyclodextrin is β-cyclodextrin, and the cyclodextrin is covalently cross-linked to the polymer matrix via epichlorohydrin; The functionalized functional groups include iminodiacetic acid groups, sulfhydryl groups and amine groups; The molar ratio of the iminodiacetic acid group, the thiol group and the amine group is (3-5): (1.5-2.5): (2.5-4); the mass ratio of the cyclodextrin to the polymer matrix is 1: (1.5-3.0).

2. A method for preparing a polymer resin for removing metal impurities in a cyanide-free cadmium plating solution as claimed in claim 1, characterized in that: The following steps are involved: Synthesis of polymer matrix by free radical polymerization; Introducing iminodiacetic acid groups, thiol groups and amine groups into the polymer matrix for functional modification to obtain a functionalized polymer; covalently cross-linking cyclodextrin to the functionalized polymer to form a three-dimensional network structure to obtain a resin mixture; The resin mixture is precipitated, washed and dried to obtain a polymer resin.

3. The method for preparing a polymer resin for removing metal impurities in a cyanide-free cadmium plating solution according to claim 2, wherein: The step of synthesizing the polymer matrix by free radical polymerization comprises: Dissolve the polymerization monomer in a solvent, add the initiator and catalyst under a nitrogen atmosphere, stir at room temperature for 0.5h-4h, then heat to 55℃-65℃ and stir for 1h-5h to complete the free radical polymerization reaction; Wherein, the polymerizable monomer is one of acrylamide, polyethylene glycol diacrylate monomer and polyvinyl alcohol monomer; The initiator is ammonium persulfate or azobisisobutyronitrile; The catalyst is N,N,N',N'-tetramethylethylenediamine.

4. The method for preparing a polymer resin for removing metal impurities in a cyanide-free cadmium plating solution according to claim 2, wherein: The step of introducing iminodiacetic acid groups, thiol groups and amine groups into the polymer matrix for functional modification to obtain a functionalized polymer comprises: During or after the free radical polymerization reaction of the polymer matrix, adding a functional monomer and reacting at 55° C.-65° C. for 1 h-5 h to graft the functional groups into the polymer matrix to obtain a functionalized polymer; The functional monomers include iminodiacetic acid functionalized acrylamide, mercapto-modified acrylamide and amine-functionalized acrylamide.

5. The method for preparing a polymer resin for removing metal impurities in a cyanide-free cadmium plating solution according to claim 2, wherein: The step of covalently cross-linking cyclodextrin to the functionalized polymer to form a three-dimensional network structure to obtain a resin mixture comprises: dissolving cyclodextrin in a solvent to obtain a cyclodextrin solution; Add epichlorohydrin to the cyclodextrin solution, and stir at room temperature for 25 min to 35 min to obtain a mixed solution; The mixed solution is added to the functionalized polymer, and the mixture is stirred and reacted at 50° C.-60° C. for 2 h-3 h to covalently cross-link the cyclodextrin to the functionalized polymer, thereby obtaining a resin mixed solution.

6. The method for preparing a polymer resin for removing metal impurities in a cyanide-free cadmium plating solution according to claim 2, wherein: The step of obtaining a polymer resin by precipitating, washing and drying the resin mixture comprises: After the resin mixture is cooled, acetone is added for precipitation, and a polymer solid is obtained by filtration. The polymer solid is then washed 3-4 times with ethanol and then vacuum-dried at 40-50° C. for 24-48 hours to obtain a polymer resin.

7. A method for using the polymer resin for removing metal impurities in a cyanide-free cadmium plating solution as claimed in claim 1, characterized in that: The following steps are involved: activating the polymer resin with a weak acid solution, and then washing with water until neutral, to obtain an activated polymer resin; contacting the activated polymer resin with a cadmium electroplating solution to adsorb metal impurities, while periodically sampling the cadmium electroplating solution to monitor the concentration of the metal impurities; After the adsorption is completed, the activated polymer resin is washed, desorbed and neutralized to regenerate the activated polymer resin into a saturated resin.

8. The method for using the polymer resin for removing metal impurities in a cyanide-free cadmium plating solution according to claim 7, wherein: The step of contacting the activated polymer resin with a cadmium electroplating solution to adsorb metal impurities comprises: The activated polymer resin is loaded into an adsorption column, and the electroplating cadmium solution is controlled to circulate through the adsorption column at a flow rate of 1BV / h-5BV / h to adsorb metal impurities.

9. The method for using the polymer resin for removing metal impurities in a cyanide-free cadmium plating solution according to claim 7, wherein: The step of contacting the activated polymer resin with a cadmium electroplating solution to adsorb metal impurities comprises: The activated polymer resin is added to the electroplating tank and stirred for 1-2 hours to allow the activated polymer resin to contact the electroplating cadmium solution to adsorb metal impurities.

10. The method for using the polymer resin for removing metal impurities in a cyanide-free cadmium plating solution according to claim 7, wherein: The steps of flushing, desorbing and neutralizing the activated polymer resin include: After rinsing the activated polymer resin with deionized water, desorption is performed with a 0.5M-1M hydrochloric acid solution for 1 hour to 2 hours, and then rinsed with deionized water. Then, the resin is neutralized with a 0.5M-1M alkaline solution and then rinsed with deionized water until neutral.

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