A polymer resin for removing metal impurities in a cyanide-free electroplating cadmium solution and a preparation method and use method thereof

Abstract

The application discloses a polymer resin for removing metal impurities in cyanide-free electroplating cadmium solution and a preparation method and use method thereof, and relates to the technical field of functional materials. The polymer resin for removing metal impurities in cyanide-free electroplating cadmium solution comprises a polymer matrix, cyclodextrin covalently cross-linked to the polymer matrix, and a functional functional group for functionalizing and modifying the polymer matrix; the functional functional group comprises imino diacetic acid group, mercapto group and amine group. The cyclodextrin is covalently cross-linked into the polymer matrix, and then modified by three functional groups with high metal affinity; through the encapsulation of the cyclodextrin and the targeted synergistic design of the three functional functional groups, the ability of the polymer resin to selectively capture metal impurities is enhanced; even in the environment competing with strong chelating agents such as EDTA and NTA, the competition barrier can be broken, and the metal impurities can be effectively combined and removed.

Description

TECHNICAL FIELD

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

[0002] Electroplated cadmium is widely used in aerospace, shipbuilding and precision instrument fields due to its super high corrosion resistance of the plating layer. However, the presence of metal impurities such as Cu 2+ , Fe 3+ , Ni 2+ , Pb 2+ and Cr 3+ in the electroplating solution will cause defects such as porosity, nodulation and adhesion reduction of the plating layer, which seriously reduces the durability of the product. In order to remove these metal impurities, the conventional means is to use small current electrolysis, add masking agents or use adsorption resins for adsorption. However, the small current electrolysis has the problem that it cannot remove all metals, and it can only remove part of the easily reduced metals (such as Cu 2+ ), and the removal rate of Fe 3+ , Cr 3+ is less than 50%; the addition of masking agents can only complex metal impurity ions to inhibit codeposition, but does not remove metal impurity ions, and long-term accumulation will cause the electroplating solution to fail; although the use of adsorption resins can remove metal impurities without polluting the electroplating solution, the adsorption efficiency is not high, and the cyanide-free process is environmentally friendly, but it relies on strong chelating agents such as ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) to stabilize cadmium ions, and these chelating agents also form stable complexes with metal impurities (such as EDTA-Fe stable constant up to 10 25 ), which makes it difficult for traditional adsorption resins to competitively bind impurity metals. Based on this, the present application provides a polymer resin for selectively removing metal impurities in cyanide-free electroplating cadmium solution. SUMMARY

[0003] The main purpose of the present application is to provide a polymer resin for removing metal impurities in cyanide-free electroplating cadmium solution and a preparation method and use method thereof, which aims to solve the technical problem that the existing method cannot effectively remove metal impurities in cyanide-free electroplating cadmium solution.

[0004] To achieve the above purpose, the present application provides a polymer resin for removing metal impurities in cyanide-free electroplating cadmium solution, which comprises:

[0005] a polymer matrix, cyclodextrin covalently cross-linked to the polymer matrix, and a functional functional group functionally modified to the polymer matrix;

[0006] The functional functional group comprises imino diacetic acid group, mercapto and amine group.

[0007] Optionally, the polymer matrix is one of polyacrylamide, polyethylene glycol diacrylate and polyvinyl alcohol; the cyclodextrin is β-cyclodextrin, and the cyclodextrin is covalently crosslinked to the polymer matrix by epichlorohydrin.

[0008] Optionally, the molar ratio of the iminodiacetic acid group, the mercapto 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).

[0009] The application also provides a preparation method of a polymer resin for removing metal impurities in a cyanide-free electroplating cadmium solution, comprising the following steps:

[0010] synthesizing a polymer matrix through a free radical polymerization reaction;

[0011] introducing iminodiacetic acid groups, mercapto groups and amine groups into the polymer matrix to perform functional modification, so as to obtain a functional polymer;

[0012] covalently crosslinking cyclodextrin to the functional polymer to form a three-dimensional network structure, so as to obtain a resin mixture;

[0013] after the resin mixture is subjected to precipitation, washing and drying, a polymer resin is obtained.

[0014] Optionally, the step of synthesizing a polymer matrix through a free radical polymerization reaction comprises:

[0015] dissolving a polymer monomer in a solvent, adding an initiator and a catalyst under a nitrogen protection atmosphere, stirring at room temperature for 0.5 h to 4 h, then increasing the temperature to 55°C to 65°C and stirring for 1 h to 5 h, so as to complete the free radical polymerization reaction;

[0016] wherein the polymer monomer is one of acrylamide, polyethylene glycol diacrylate monomer and polyvinyl alcohol monomer;

[0017] the initiator is ammonium persulfate or azobisisobutyronitrile;

[0018] the catalyst is N,N,N',N'-tetramethyl ethylenediamine.

[0019] Optionally, the step of introducing iminodiacetic acid groups, mercapto groups and amine groups into the polymer matrix to perform functional modification, so as to obtain a functional polymer comprises:

[0020] adding a functional monomer during or after the free radical polymerization reaction of the polymer matrix, and reacting at 55°C to 65°C for 1 h to 5 h, so as to graft the functional groups into the polymer matrix, thereby obtaining a functional polymer;

[0021] wherein the functional monomer comprises imido diacetic acid functionalized acrylamide, thiol modified acrylamide and amine functionalized acrylamide.

[0022] Optionally, the step of covalently crosslinking the cyclodextrin to the functionalized polymer to form a three-dimensional network structure to obtain a resin mixture, comprises:

[0023] dissolving the cyclodextrin in a solvent to obtain a cyclodextrin solution;

[0024] adding epichlorohydrin to the cyclodextrin solution, and stirring at room temperature for 25-35 min to obtain a mixture;

[0025] adding the mixture to the functionalized polymer, and stirring at 50-60°C for 2-3 h to covalently crosslink the cyclodextrin to the functionalized polymer to obtain a resin mixture.

[0026] Optionally, the step of obtaining the polymer resin after precipitating, washing and drying the resin mixture, comprises:

[0027] cooling the resin mixture, precipitating in acetone, filtering to obtain a polymer solid, washing the polymer solid with ethanol for 3-4 times, and vacuum drying at 40-50°C for 24-48 h to obtain the polymer resin.

[0028] The application also provides a use method of the polymer resin for removing metal impurities in a cyanide-free electroplating cadmium solution, comprising the following steps:

[0029] activating the polymer resin by a weak acid solution, and then washing with water to neutral to obtain an activated polymer resin;

[0030] contacting the activated polymer resin with the electroplating cadmium solution to adsorb metal impurities, and periodically sampling the electroplating cadmium solution to monitor the concentration of metal impurities;

[0031] after adsorption, washing, desorption and neutralizing the activated polymer resin to regenerate the activated polymer resin into a saturated resin.

[0032] Optionally, the step of contacting the activated polymer resin with the electroplating cadmium solution to adsorb metal impurities, comprises:

[0033] loading the activated polymer resin into an adsorption column, and circulating the electroplating cadmium solution through the adsorption column at a flow rate of 1-5 BV / h to adsorb metal impurities.

[0034] Optionally, the step of contacting the activated polymer resin with the electroplating cadmium solution to adsorb metal impurities, comprises:

[0035] adding the activated polymer resin into the electroplating tank, stirring for 1-2h, and allowing the activated polymer resin to contact with the electroplating cadmium solution to adsorb metal impurities.

[0036] Optionally, the steps of rinsing, desorbing and neutralizing the activated polymer resin comprise:

[0037] After rinsing the activated polymer resin with deionized water, desorbing with 0.5M-1M hydrochloric acid solution for 1-2h, rinsing with deionized water, and neutralizing with 0.5M-1M alkaline solution, and then rinsing with deionized water until neutral.

[0038] The present application at least includes the following beneficial effects:

[0039] The present application designs three functional groups with high metal affinity, including imino diacetic acid group, thiol group and amine group. The imino diacetic acid group can preferentially capture transition metals through bidentate chelation, and its binding constant for Fe 3+ , Ni 2+ , etc. is greater than that of EDTA and NTA, while the thiol group can form a covalent bond with Cu 2+ , Pb 2+ , etc., thereby specifically adsorbing heavy metals. The amine group has a broad spectrum of ion exchange properties and can adsorb anionic impurities by protonation (-NH3 + ), thereby covering multiple types of metal impurities. Through the targeted and synergistic design of the three functional groups, the polymer resin can provide stronger metal impurity binding capacity. Even in a competitive environment with strong chelating agents such as EDTA and NTA, it can still break through the competitive barrier 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 necessary cadmium ions remain in the solution.

[0040] The present application introduces cyclodextrin into the polymer matrix through covalent cross-linking. Cyclodextrin has a hydrophobic cavity that can include metal-EDTA, metal-NTA and other complexes to form inclusion compounds. Under the action of inclusion, the coordination bond of EDTA and NTA can be broken, exposing free metal ions to 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.

[0041] The polymer resin of the present application has reversible regenerability. Acid desorption can break the coordination bond between metal and functional groups without damaging the covalent cross-linked skeleton, and alkaline neutralization can restore the protonation ability of the amine group. After multiple regenerations, the polymer resin still has excellent adsorption rate, thereby reducing the frequency of replacing the polymer resin and reducing the operating cost.

[0042] The polymer resin of the present application can form a three-dimensional stable network after being cross-linked by cyclodextrin, thereby improving its stability and being adaptable to the operating conditions of various cadmium electroplating solutions. Even under different pH and temperature conditions, the polymer resin can effectively remove metal impurities, ensuring the purity of the cadmium electroplating solution and the quality of the plated layer. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0044] Figure 1 The preparation method flow chart of the polymer resin described in the embodiments of the present application is shown in the following figure.

[0045] Figure 2 The use method flow chart of the polymer resin described in the embodiments of the present application is shown in the following figure.

[0046] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0048] In view of the technical problems existing in the prior art, the embodiments of the present application provide a polymer resin for removing metal impurities in a cyanide-free cadmium electroplating solution, which comprises:

[0049] a polymer matrix, cyclodextrin covalently cross-linked to the polymer matrix, and a functional functional group functionally modified to the polymer matrix.

[0050] The functional functional group comprises imino diacetic acid group, mercapto group and amine group.

[0051] The application introduces cyclodextrin into the polymer matrix by covalent crosslinking, and then modifies it by 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 action of inclusion, the coordination bond of EDTA and NTA can be destroyed, and free metal ions are exposed. At the same time, the imino diacetic acid group can preferentially capture transition metals through bidentate chelation. Its binding constant for Fe 3+ , Ni 2+ , etc. is greater than that of EDTA and NTA, while the thiol group can form a covalent bond with Cu 2+ , Pb 2+ , etc. to specifically adsorb heavy metals. The amine group has a broad spectrum of ion exchange properties and can adsorb anionic impurities by protonation (-NH3 + ), covering multiple types of metal impurities. Through the inclusion action of cyclodextrin and the targeted synergistic design of three functional groups, not only the ability of the polymer resin to selectively capture metal impurities is enhanced, but also the metal impurity binding capacity of the polymer resin is improved. Even in the presence of strong chelating agents such as EDTA and NTA, the competitive barrier can still be broken, effectively binding and removing metal impurities. This selective removal ensures that only unwanted metal ions are captured, while 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.

[0052] As an implementable manner of the application, the polymer matrix is one of polyacrylamide, polyethylene glycol diacrylate and polyvinyl alcohol; the cyclodextrin is β-cyclodextrin, and the cyclodextrin is covalently crosslinked to the polymer matrix by epichlorohydrin.

[0053] The application uses polyacrylamide, polyethylene glycol diacrylate and polyvinyl alcohol as the polymer matrix, which can provide abundant grafting sites as a polar backbone, has high functional capacity, and can provide the polymer resin with the structural integrity of the polymer and high surface area functionalization.

[0054] Specifically, the cavity size of β-cyclodextrin is 0.65nm-0.78nm, and single-6-deoxy-6-amino-β-cyclodextrin is preferably used. It can wrap the hydrophobic group (-CH2-) of EDTA through hydrophobic interaction, and the inclusion action can make the conformation of EDTA distorted, which leads to the deviation of the M + -O / N coordination bond angle and the decrease of bond energy, and the weakened coordination bond is broken under thermal motion, so that the free metal ion (M + ) is exposed to the action range of the 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.

[0055] 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).

[0056] The present application optimizes the ratio of the iminodiacetic acid group, the thiol group and the amine group, and the ratio of the cyclodextrin to the polymer matrix, to ensure that the polymer resin has sufficient crosslinking density, and the three functionalized functional groups are uniformly grafted, avoiding local saturation, so that the polymer resin can stably bind Fe 3+ , Ni 2+ , Cu 2+ , Pb 2+ and many other metal impurity ions.

[0057] The embodiment of the present application also provides a preparation method of a polymer resin for removing metal impurities in a cyanide-free electroplating cadmium solution, as shown in the following formula: Figure 1 The preparation method comprises the following steps:

[0058] S10, synthesizing a polymer matrix through a free radical polymerization reaction.

[0059] In the specific implementation process, the polymer monomer is dissolved in a solvent, the solvent is water or ethanol, an initiator and a catalyst are added under a nitrogen protective atmosphere, stirring is performed at room temperature for 0.5h-4h, then the temperature is increased to 55℃-65℃, and stirring is performed for 1h-5h, and the free radical polymerization reaction is completed;

[0060] The polymer monomer is one of acrylamide, polyethylene glycol diacrylate monomer and polyvinyl alcohol monomer;

[0061] The initiator is ammonium persulfate or azobisisobutyronitrile;

[0062] The catalyst is N,N,N',N'-tetramethyl ethylenediamine.

[0063] The present application uses ammonium persulfate or azobisisobutyronitrile as an initiator, and uses N,N,N',N'-tetramethyl ethylenediamine as a catalyst, to initiate a free radical polymerization reaction of the polymer monomer to synthesize a polymer matrix, and to provide sufficient chain length and crosslinking points for subsequent covalent crosslinking of cyclodextrin.

[0064] S11, introducing iminodiacetic acid groups, thiol groups and amine groups into the polymer matrix to perform functional modification, to obtain a functional polymer.

[0065] In the specific implementation process, the functional monomer is added during the free radical polymerization of the polymer matrix or after the reaction, and the functional group is grafted to the polymer matrix by reacting at 55-65℃ for 1-5h to obtain a functional polymer;

[0066] The functional monomer includes iminodiacetic acid functional acrylamide, thiol-modified acrylamide, and amine functional acrylamide.

[0067] The iminodiacetic acid functional acrylamide can use N-(2-carboxyethyl) iminodiacetic acid, which has an iminodiacetic acid group and can preferentially capture transition metals mainly through bidentate chelation, which can compete with EDTA and NTA to provide stronger metal impurity binding capacity; the thiol-modified acrylamide can use 2-mercaptoethyl acrylate, which has a thiol group and can specifically adsorb main heavy metals Cu 2+ , Pb 2+ , etc. in the electroplating cadmium solution, and the amine functional acrylamide uses acrylamide with a primary amine group, which can provide a broad spectrum of ion exchange capacity to capture various metal impurities. By incorporating the functional monomer during or after polymerization to modify the polymer matrix, the polymer matrix is functionalized to have a high density of active sites to ensure maximum interaction with metal impurities.

[0068] S12, covalently cross-linking cyclodextrin to the functional polymer to form a three-dimensional network structure to obtain a resin mixture.

[0069] In the specific implementation process, the cyclodextrin is dissolved in a solvent to obtain a cyclodextrin solution;

[0070] Epichlorohydrin is added to the cyclodextrin solution, and the mixture is stirred at room temperature for 25-35min to obtain a mixture;

[0071] The mixture is added to the functional polymer, and the mixture is stirred and reacted at 50-60℃ for 2-3h to covalently cross-link the cyclodextrin to the functional polymer to obtain a resin mixture.

[0072] Specifically, the cyclodextrin is covalently bonded to the polymer through epichlorohydrin, rather than physically doped, which can form a rigid network of the polymer resin to improve the stability of the polymer resin. Even under various electroplating conditions, the electroplating solution has different pH values and temperatures, and the polymer resin can stably remove metal impurities. The inclusion effect of cyclodextrin can create a microenvironment in the polymer matrix that is conducive to capturing specific ions, forming a three-dimensional network structure of the polymer resin with metal ion capture active sites, thereby enhancing the ability of the polymer resin to selectively capture metal impurities.

[0073] S13, obtaining the polymer resin after precipitating, washing and drying the resin mixture.

[0074] In the specific implementation, the resin mixture is cooled, precipitated in acetone, filtered to obtain polymer solids, washed with ethanol for 3-4 times, and vacuum dried at 40-50°C for 24-48h to obtain the polymer resin.

[0075] The embodiments of the present application also provide a use method of the polymer resin for removing metal impurities in a cyanide-free electroplating cadmium solution, as shown in the formula (I), comprising the following steps: Figure 2

[0076] S20, activating the polymer resin by a weak acid solution, and then washing the activated polymer resin with water until neutral to obtain an activated polymer resin.

[0077] Specifically, the polymer resin needs to be activated before use, which can be washed by 0.1M hydrochloric acid to ensure that the functional groups are in ionic form, and then the polymer resin is thoroughly washed with deionized water to remove residual acid.

[0078] S21, contacting the activated polymer resin with the electroplating cadmium solution to adsorb metal impurities, and periodically sampling the electroplating cadmium solution to monitor the concentration of metal impurities.

[0079] In the specific implementation, 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 of the solution allowed to fully contact with the resin, the activated polymer resin is loaded into the adsorption column, and the adsorption column is connected to a circulation system to control the electroplating cadmium solution to circulate through the adsorption column at a flow rate of 1-5BV / h to ensure that the metal impurities have enough time to be adsorbed by the polymer resin.

[0080] In the specific implementation, the activated polymer resin can be directly added to the electroplating tank, continuously stirred for 1-2h to make the activated polymer resin fully contact with the electroplating cadmium solution to adsorb metal impurities.

[0081] Specifically, the concentration of metal impurities can be monitored by atomic absorption spectrometry (AAS) or inductively coupled plasma mass spectrometry (ICP-MS) during the adsorption process until the impurity concentration is reduced to the required level.

[0082] S22, washing, desorbing and neutralizing the activated polymer resin to regenerate the activated polymer resin into a saturated resin.

[0083] ​In the implementation process, first, the activated polymer resin is washed with deionized water to remove residual plating solution, which helps to prevent the formation of precipitates and prepares for effective desorption process, then 0.5M-1M hydrochloric acid solution is used for desorption for 1h-2h, ensuring that the hydrochloric acid solution is in full contact with the polymer resin, and the metal ion concentration of the desorbed solution is tested to confirm that most of the impurities on the polymer resin have been removed, then deionized water is used for washing to remove the residual acid, and then 0.5M-1M sodium hydroxide or sodium bicarbonate solution is used for neutralization, and then deionized water is used for washing to neutralization, so as to regenerate into saturated resin.

[0084] To ensure that the functional groups on the polymer resin are in the best ionic state, the polymer resin can also be soaked in dilute acid (such as 0.1M acetic acid) and then washed with deionized water, which helps to restore the functional groups (such as iminodiacetic acid) of the polymer resin to an active state, ensuring that they can effectively adsorb metal ions in the next cycle.

[0085] The above technical solutions of the present application will be described in detail below in conjunction with specific examples.

[0086] Example 1 Preparation and application of polyacrylamide-based resin

[0087] Preparation steps:

[0088] Step 1, preparation of materials and reagents

[0089] Acrylamide (main chain polymerization monomer): 500g;

[0090] Iminodiacetic acid functionalized acrylamide (using N-(2-carboxyethyl) iminodiacetic acid): 125g;

[0091] Thiol-modified acrylamide (using 2-mercaptoethyl acrylate): 75g;

[0092] Amine-functionalized acrylamide (acrylamide with primary amine group): 125g;

[0093] Cyclodextrin (mono-6-deoxy-6-amino-β-cyclodextrin): 250g;

[0094] Crosslinking agent (epichlorohydrin): 125g;

[0095] Solvent: water, dimethyl sulfoxide (DMSO), acetone, ethanol;

[0096] Initiator (ammonium persulfate): 10g;

[0097] Catalyst (N,N,N',N'-tetramethyl ethylenediamine, TEMED): 10g.

[0098] Step 2, Polymerization reaction

[0099] A 3L-5L reactor was prepared with a mechanical stirrer and purged with nitrogen to maintain an inert atmosphere. 2L of deionized water was added to the reactor, and acrylamide was dissolved in the deionized water. Iminodiacetic acid-functionalized acrylamide, thiol-modified acrylamide, and amine-functionalized acrylamide were then added. The mixture was stirred at room temperature for 1 hour to ensure complete dissolution of all monomers, resulting in a monomer solution. If complete dissolution did not occur, 100 mL of DMSO could be added to improve solubility.

[0100] Under a nitrogen atmosphere, ammonium persulfate and TEMED were added to the monomer solution to initiate the free radical polymerization reaction. The mixture was stirred at room temperature for 3 hours, and then the temperature was gradually increased to 60°C for another hour to complete the polymerization, resulting in a functionalized polymer.

[0101] During the polymerization reaction, the progress of the polymerization was monitored by observing the viscosity of the solution. As the polymer chains formed, the solution should gradually thicken.

[0102] Step 3, Crosslinking with cyclodextrin

[0103] Mon-6-deoxy-6-amino-β-cyclodextrin was dissolved in 500 mL of water, and epichlorohydrin was added. The mixture was stirred at room temperature for 30 minutes to obtain a mixed solution.

[0104] The mixed solution was added to the functionalized polymer under continuous stirring, and the temperature was increased to 50°C. The mixture was stirred for 2 hours. During this time, epichlorohydrin acted as a crosslinking agent, binding cyclodextrin to the polymer backbone, resulting in a resin mixture.

[0105] During the crosslinking process, the viscosity of the solution and the gelation process were monitored to confirm the progress of the crosslinking.

[0106] Step 4, Precipitation and purification

[0107] After the completion of the crosslinking reaction, the resin mixture was cooled to room temperature.

[0108] The resin mixture was added to 10 L of acetone under vigorous stirring. The polymer precipitated as a solid, which was filtered using a Buchner funnel to obtain a polymer solid.

[0109] The polymer solid was washed three times with ethanol to remove unreacted monomers, cyclodextrin, and crosslinking agent residues. The polymer was then vacuum-dried at 40°C for 36 hours until a constant weight was achieved, resulting in a crosslinked polyacrylamide resin containing iminodiacetic acid, thiol, and amine functional groups.

[0110] Applications:

[0111] 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;

[0112] 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.

[0113] Table 1

[0114]

[0115] 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%.

[0116] Regeneration:

[0117] 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.

[0118] Example 2 Preparation and Application of Polyethylene Glycol Diacrylate-Based Resin

[0119] Preparation steps:

[0120] Step 1. Prepare materials and reagents

[0121] Polyethylene glycol diacrylate (molecular weight about 4000g / mol-6000g / mol, as the main chain): 1000g;

[0122] Iminodiacetic acid functionalized acrylamide (using N-(2-carboxyethyl)iminodiacetic acid): 200g;

[0123] Mercapto-modified acrylamide (using 2-mercaptoethyl acrylate): 120g;

[0124] Amine-functionalized acrylamide (acrylamide with primary amine groups): 150g;

[0125] Cyclodextrin (Mono-6-deoxy-6-amino-β-cyclodextrin): 300 g;

[0126] Crosslinker (epichlorohydrin): 150 g;

[0127] Solvents: water, acetone, ethanol;

[0128] Initiator (Azobisisobutyronitrile, AIBN): 20 g.

[0129] Step 2, Polymerization Reaction

[0130] Prepare a 3L-5L reaction vessel equipped with a mechanical stirrer and purged with nitrogen to maintain an inert atmosphere. Add 1.5L of ethanol to the reaction vessel. Under continuous stirring, dissolve the polyethylene glycol diacrylate in ethanol, ensuring complete dissolution and formation of a homogeneous solution. Slowly add the imino diacetic acid-functionalized acrylamide, thiol-modified acrylamide, and amine-functionalized acrylamide. Stir at room temperature for 0.5h to ensure uniform mixing of all monomers, resulting in a monomer solution.

[0131] Under a nitrogen atmosphere, add azobisisobutyronitrile to the monomer solution and stir. Increase the temperature to 60°C and maintain the stirring for 4h to initiate the free radical polymerization reaction, resulting in a functionalized polymer.

[0132] During the polymerization reaction, monitor the progress of the polymerization reaction by monitoring the viscosity of the solution. As the polymer chains form, a viscous solution gradually forms.

[0133] Step 3, Crosslinking with Cyclodextrin

[0134] Dissolve the mono-6-deoxy-6-amino-β-cyclodextrin in 1L of water. After complete dissolution, add epichlorohydrin and stir at room temperature for 30min to obtain a mixture.

[0135] Slowly add the mixture to the functionalized polymer under continuous stirring. Heat to 50°C and maintain stirring for 3h. During this period, epichlorohydrin promotes the formation of covalent bonds between cyclodextrin and the polymer backbone, forming a crosslinked network, resulting in a resin mixture.

[0136] During the crosslinking process, monitor the viscosity and gelation process of the solution to confirm the progress of crosslinking.

[0137] Step 4, Precipitation and Purification

[0138] After the completion of the crosslinking reaction, cool the resin mixture to room temperature.

[0139] Under vigorous stirring, add the resin mixture to 10L of acetone. The polymer will precipitate as a solid. Filter using a Buchner funnel to obtain the polymer solid.

[0140] The polymer solid was washed 4 times with ethanol to remove unreacted monomers, cyclodextrin and crosslinker residues, and then vacuum dried at 40°C for 48h until constant weight was achieved to obtain a crosslinked polyethylene glycol diacrylate resin containing imino diacetic acid, thiol and amine functional groups.

[0141] Applications:

[0142] The crosslinked polyethylene glycol diacrylate resin was washed with 0.1M hydrochloric acid and then rinsed with deionized water until neutral to remove residual acid to obtain an activated polymer resin;

[0143] The activated polymer resin was directly added to the electroplating tank at an amount of 3g / L, and directly contacted with an electroplating cadmium solution (pH 3) containing 10ppm Ni 2+ , 5g / L EDTA, and continuously stirred for 1.5h to allow the activated polymer resin to fully adsorb metal impurities in the electroplating cadmium solution, while periodically sampling the electroplating cadmium solution to detect the concentration of metal impurities by inductively coupled plasma mass spectrometry. The metal impurity ion concentration after 2h is shown in Table 2.

[0144] Table 2

[0145]

[0146] As can be seen from Table 2, the polymer resin of the present embodiment can also effectively adsorb Ni 2+ in an acidic environment, and the removal rate of Ni 2+ can reach 98.8%.

[0147] Regeneration:

[0148] After adsorption, the polymer resin was rinsed with deionized water to remove residual electroplating cadmium solution, and then desorbed with 0.5M hydrochloric acid solution for 1h and tested for metal ion concentration 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, neutralized with 0.5M sodium hydroxide, and then rinsed with deionized water until neutral to regenerate into a saturated resin.

[0149] Example 3 Preparation and application of polyvinyl alcohol-based resin

[0150] Preparation steps:

[0151] Step 1, preparation of materials and reagents

[0152] Polyvinyl alcohol (molecular weight about 70000g / mol-100000g / mol as main chain): 1000g;

[0153] Iminodiacetic acid functionalized acrylamide (using N-(2-carboxyethyl)iminodiacetic acid salt): 150 g;

[0154] Mercapto-modified acrylamide (using 2-mercaptoethyl acrylate): 100 g;

[0155] Amino-functionalized acrylamide (acrylamide with primary amine group): 100 g;

[0156] Cyclodextrin (mono-6-deoxy-6-amino-β-cyclodextrin): 300 g;

[0157] Crosslinking agent (epichlorohydrin): 200 g;

[0158] Solvent: water, acetone, ethanol;

[0159] Initiator (ammonium persulfate): 20 g;

[0160] Catalyst (N,N,N',N'-tetramethyl ethylenediamine, TEMED): 10 g.

[0161] Step 2, polymerization reaction

[0162] Prepare a 3L-5L reaction kettle equipped with a mechanical stirrer and purged with nitrogen to maintain an inert atmosphere, add 3L deionized water to the reaction kettle, dissolve polyvinyl alcohol in deionized water, heat to 80°C, and stir for 1 h until the polyvinyl alcohol is completely dissolved;

[0163] Dissolve the iminodiacetic acid functionalized acrylamide, mercapto-modified acrylamide and amino-functionalized acrylamide in 300 mL water to obtain a functionalized monomer mixture;

[0164] Slowly add the functionalized monomer mixture to the polyvinyl alcohol aqueous solution under stirring, continue stirring at 60°C for 1 h to ensure uniform mixing, then add ammonium persulfate and TEMED to initiate the radical polymerization reaction, and stir at 60°C for 3 h to obtain a functionalized polymer;

[0165] During the polymerization reaction, the progress of the polymerization reaction is checked by monitoring the viscosity of the solution. As the polymer chains form, the solution should gradually thicken.

[0166] Step 3, crosslinking with cyclodextrin

[0167] Dissolve mono-6-deoxy-6-amino-β-cyclodextrin in 500 mL water, then add epichlorohydrin, stir at room temperature for 30 min to obtain a mixture;

[0168] The mixture was added to the functionalized polymer under constant stirring, heated to 60°C and kept stirring for 2h, during which the epichlorohydrin, as a crosslinking agent, bound the cyclodextrin to the polymer backbone, obtaining a resin mixture;

[0169] During the crosslinking process, the viscosity of the solution and the gelation process were monitored to confirm the progress of the crosslinking.

[0170] Step 4, precipitation and purification

[0171] After the completion of the crosslinking reaction, the resin mixture was cooled to room temperature;

[0172] The resin mixture was added to 10L of acetone under vigorous stirring, the polymer will precipitate in the form of a solid, filtered using a Buchner funnel, obtaining the polymer solid;

[0173] The polymer solid was washed 3 times with ethanol to remove unreacted monomers, cyclodextrin and crosslinking agent residues, and vacuum dried at 40°C for 24h until reaching constant weight, obtaining the crosslinked polyvinyl alcohol resin containing imino diacetic acid, thiol and amine functional groups.

[0174] Applications:

[0175] The crosslinked polyvinyl alcohol resin described above was washed with 0.1M hydrochloric acid and then rinsed with deionized water until neutral to remove residual acid, obtaining the activated polymer resin;

[0176] The activated polymer resin was loaded into an adsorption column, which was then connected to a circulation system to control the circulation of a plating cadmium solution (pH 8.0) containing 8ppm Pb 2+ at a flow rate of 2BV / h through the activated polymer resin to ensure that the metal impurities have enough time to be adsorbed, while periodically sampling the plating cadmium solution and detecting the concentration of metal impurities by atomic absorption spectrometry, recording the concentrations of metal impurity ions after 10min, 30min and 60min of treatment, respectively, as shown in Table 3 below.

[0177] Table 3

[0178]

[0179] As can be seen from Table 3, the polymer resin of the present embodiment can quickly adsorb Pb 2+ in the plating cadmium solution, and the concentration of Pb 2+ is significantly reduced after 60min.

[0180] Regenerability:

[0181] After the adsorption is completed, the polymer resin is washed with deionized water to remove the residual electroplating cadmium solution, then desorbed with 1M hydrochloric acid solution for 1h, and the metal ion concentration is tested to confirm that most of the impurities on the polymer resin have been removed, then the polymer resin is washed with deionized water to remove the residual acid, then neutralized with 1M sodium hydroxide, and then washed with deionized water to neutralization, thereby regenerated into saturated resin.

[0182] The above is only an optional embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or the like made under the inventive concept of the present application, using the contents of the present application specification and drawings, are all 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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