CN112958041B

CN112958041B - Core-shell structure nano composite resin, preparation method and application in electroplating wastewater treatment

Info

Publication number: CN112958041B
Application number: CN202110184215.3A
Authority: CN
Inventors: 王小青; 张靖; 王永江; 韩小瑜; 徐子萌; 叶统; 姬澳琪; 熊春华
Original assignee: Zhejiang Lover Health Science and Technology Development Co Ltd
Current assignee: Zhejiang Lover Health Science and Technology Development Co Ltd
Priority date: 2021-02-08
Filing date: 2021-02-08
Publication date: 2022-08-02
Anticipated expiration: 2041-02-08
Also published as: CN112958041A

Abstract

The invention discloses a core-shell structure nano composite resin Co-MOF-D113-1, a preparation method and application thereof, wherein the nano composite resin is synthesized by taking D113 as a matrix and dimethyl imidazole and cobalt acetate as D113 precursors by adopting a layer-by-layer self-assembly method. The invention has the beneficial effects that: combining macro and micro size materials to form a nanocomposite material with excellent performance; the reaction process is simple and convenient, and is green; the Co-MOF-D113-1 material has a novel structure and high research value; the adsorption effect on heavy metal ions is better than that of the prior art; the core-shell structure nano composite resin material has good adsorption stability and reusability, and can be applied to adsorption and purification of heavy metal ions in water.

Description

Core-shell structure nano composite resin, preparation method and application in electroplating wastewater treatment

Technical Field

The invention relates to the technical field of composite material synthesis, in particular to core-shell structure nano composite resin combined by weak acid type ion exchange adsorption resin and a metal organic framework compound, a preparation method and application.

Background

Currently, MOFs have become an important research direction for many chemical branches of inorganic chemistry, organic chemistry, and the like. The MOF has large internal specific surface area and high permanent porosity, and the porosity and functional sites of the MOF can be accurately adjusted through reasonable selection of metal nodes and modification of organic ligands. The existence of open metal sites and appropriate pore size can provide binding sites for heavy metal ions, making MOF an ideal adsorbing material for various heavy metal ions.

However, D113 is a macroscopic opaque yellowish spherical particle, and the specific surface area of the particle is still greatly improved compared with MOF; the MOF is a nano-grade material, has small volume, and is easy to agglomerate and difficult to separate.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a core-shell structure nano composite resin Co-MOF-D113-1.

In order to achieve the purpose, the invention provides the following technical scheme: a core-shell structure nanocomposite resin Co-MOF-D113-1 is characterized in that D113 is used as a matrix, dimethylimidazole and cobalt acetate are used as precursors of D113, the nanocomposite resin is synthesized by a layer-by-layer self-assembly method, and the layer-by-layer self-assembly is 1-time wrapping.

A preparation method of core-shell structure nano composite resin Co-MOF-D113-1 comprises the following steps,

(1) pretreatment of raw materials: soaking and swelling the ion exchange adsorption resin D113 in distilled water for more than 24 hours, and washing and filtering the ion exchange adsorption resin with deionized water to obtain pretreated resin; (2) preparation of 2-MI/D113: adding the pretreated resin prepared in the step (1) into a 2-methylimidazole solution, carrying out staged reaction in a microwave reactor under an oxygen-isolated condition, repeatedly washing products with absolute ethyl alcohol and deionized water respectively after the reaction is finished, carrying out suction filtration and drying to obtain 2-MI/D113 resin; (3) preparation of Co-MOF-D113-1: and (3) adding the 2-MI/D113 resin prepared in the step (2) into a cobalt acetate solution, carrying out staged reaction in a microwave reactor under an oxygen-isolated condition, repeatedly washing products with absolute ethyl alcohol and deionized water respectively after the reaction is finished, carrying out suction filtration, and drying to obtain the Co-MOF-D113-1 resin.

Preferably, the feeding ratio of the distilled water to the ion exchange adsorption resin is 20-100 mL: 2g of the total weight.

Preferably, in the step (2), the solvent of the 2-methylimidazole solution is deionized water, and the feeding ratio of the deionized water to the 2-methylimidazole is 30 mL: 0.5-3 g; the oxygen isolation condition is that nitrogen or inert gas is introduced into the reaction system.

Preferably, in the step (3), the cobalt acetate solution solvent is deionized water, and the feed ratio of the deionized water to the cobalt acetate is 30 mL: 1.5-3 g.

Preferably, the staged reaction processes in the microwave reactor in the step (2) and the step (3) are respectively as follows: under the condition of constant temperature, setting the power to be 200W, the reaction temperature to be 60-80 ℃ and the reaction time to be 5-20 min; under the condition of constant temperature, the set power is 600-800W, the reaction temperature is 100-105 ℃, and the reaction time is 40-60 min.

Preferably, the nanocomposite resin is a metal ion Cu ²⁺ Has selective adsorption.

Preferably, the nanocomposite resin is applied to Cu in environment or food ²⁺ Adsorption of (3).

Preferably, adsorbed Cu ²⁺ 100% desorption is achieved in a 2mol/L hydrochloric acid solution system.

Preferably, after repeating the adsorption-desorption cycle 10 times, the nanocomposite resin is used for Cu ²⁺ The adsorption amount of (A) is still 87% or more of the first adsorption amount.

The invention has the beneficial effects that: combining macro and micro size materials to form a nanocomposite material with excellent performance; the reaction process is simple and convenient, and is green; the Co-MOF-D113-1 material has a novel structure and high research value; the adsorption effect on heavy metal ions is better than that of the prior art; and the Co-MOF-D113-1 material has good adsorption stability and reusability, and can be applied to adsorption and purification of heavy metal ions in water.

Drawings

FIG. 1 is a schematic structural diagram of a core-shell structure nanocomposite resin Co-MOF-D113-1 according to the present invention;

FIG. 2 is a schematic reaction principle diagram of the core-shell structure nanocomposite resin Co-MOF-D113-1 of the present invention;

FIG. 3 shows the Co-MOF-D113-1 and D113, 2 of the present invention-MI、CoAC ₂ An infrared spectrum of (1);

FIG. 4 is a schematic structural diagram of the core-shell structure nanocomposite resin Co-MOF-D113-1 of the invention after adsorption;

FIG. 5 shows the core-shell structure nanocomposite Co-MOF-D113-1 vs Cu under different pH conditions of the present invention ²⁺ A graph showing the adsorption amount (35 ℃ C., 24 hours) of (A);

FIG. 6 is a graph showing the effect of adsorption time on the amount of adsorption at different temperatures according to the present invention (pH 5.5);

FIG. 7 is a graph showing the adsorption rate and elution rate of the present invention at different cycle numbers.

Detailed Description

The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments. It should be noted that the experimental methods used in the following examples are all conventional methods unless otherwise specified; materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially. In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below.

Example 1

D113 is polyacrylic acid type weak acid type resin taking itaconic acid allyl ester as a main cross-linking agent and divinylbenzene as a secondary cross-linking agent. The D113 resin with good quality is in a regular spherical shape, uniform milky white, high in strength, not easy to break, free of abnormal particles, free of impurities and basically free of broken balls, and the sphere rate is 100%. D113 shows excellent separation and enrichment performance, and has the advantages of low cost, large adsorption capacity, good strength and repeated use. D113 has gaps among polymer chains in a swelling state and macropores (several to hundreds of nanometers) generated by a pore-foaming agent during synthesis; macropores can remain after water loss despite the disappearance of interchain voids. The D113 has the advantages of stable framework structure, rich surface functional groups, adjustable pore channel structure, large adsorption capacity and the like, and is suitable for selective adsorption and separation of various heavy metal ions. Wherein, D113 with N, O, S, P coordination groups on the surface can generate strong affinity to certain heavy metal ions or certain heavy metal ions, and can realize selective separation and removal through complexation.

The metal-organic framework Material (MOF) is a coordination polymer which develops rapidly in the last decade, has a three-dimensional porous structure, generally takes metal ions as connecting points, and supports an organic ligand to form a space 3D structure, is another important novel porous material besides zeolite and carbon nanotubes, and has wide application in catalysis, energy storage and separation.

This example suggests that MOF materials, if they can be bound to relatively macroscopic objects, achieve better adsorption and are easily separated by their synergistic effect. Specifically, in this example, D113 and MOF were combined to improve adsorption capacity by synergistic adsorption.

Based on a low-cost high-molecular material weak-acid resin with a large specific surface area as a support material, carboxyl groups in the weak-acid resin are modified, 2-methylimidazole and cobalt acetate are used as ligands, a microwave synthesis method is adopted to prepare a core-shell structure nano composite resin Co-MOF-D113-1, and the resin can be widely applied to Cu2 ⁺ In the separation adsorption recovery.

Therefore, this example provides a core-shell nanocomposite resin Co-MOF-D113-1 (or Co-MOF/D113-1) nanocomposite resin, which is synthesized by taking D113 as a matrix and dimethyl imidazole and cobalt acetate as D113 precursors by a layer-by-layer autonomous synthesis method, and has a structural formula shown in fig. 1, and a chemical formula [ Co (mi) ] ₂ ] _n @ D113 (the structure of the hybrid part is an organic framework compound ZIF-67, MI is 2-methylimidazole, n is a positive integer which is not zero, and the carrier D113 is hydrogen type acrylic acid copolymerization macroporous resin.

Example 2

The embodiment provides a method for preparing core-shell structure nano composite resin Co-MOF-D113-1, which comprises the following process steps:

(1) pretreatment of raw materials: soaking and swelling the ion exchange adsorption resin D113 in distilled water for more than 24 hours, and washing and filtering the ion exchange adsorption resin with deionized water to obtain the pretreatment resin.

The specific operation is as follows: 50ml of distilled water is weighed into a 100ml three-necked flask, 2g of weak acid type ion exchange adsorption resin (D113) is accurately weighed and added into the three-necked flask, and the three-necked flask is kept stand and swelled for 24 hours.

(2) Preparation of 2-MI/D113: and (2) adding the pretreated resin prepared in the step (1) into a 2-methylimidazole solution, carrying out staged reaction in a microwave reactor under an oxygen-isolated condition, repeatedly washing products with absolute ethyl alcohol and deionized water respectively after the reaction is finished, carrying out suction filtration, and drying to obtain the 2-MI/D113 resin.

The method specifically comprises the following steps: 15ml of distilled water was weighed into a 50ml three-necked flask, 2.28g of 2-methylimidazole (2-MI) was accurately weighed and added to the three-necked flask with distilled water to be dissolved sufficiently, and then added to D113, and the mixture was stirred at 35 ℃ for 1 hour, centrifuged, and washed with distilled water to obtain 2-MI/D113.

(3) Preparation of Co-MOF-D113-1: and (3) adding the 2-MI/D113 resin prepared in the step (2) into a cobalt acetate solution, carrying out staged reaction in a microwave reactor under an oxygen-isolated condition, repeatedly washing products with absolute ethyl alcohol and deionized water respectively after the reaction is finished, carrying out suction filtration, and drying to obtain the Co-MOF-D113-1 resin.

The method specifically comprises the following steps: 15ml of distilled water is weighed into a 50ml three-necked bottle, 4.92g of cobalt acetate is accurately weighed and added into the three-necked bottle with the distilled water for full dissolution, and 2-MI/D113 is added into the cobalt acetate solution. Stirring for 1h at 35 ℃, centrifuging, washing the product with distilled water, and drying the product at 40-60 ℃ under a vacuum condition until the weight is constant to obtain Co-MOF-D113-1.

Further, the reaction conditions in each step are preferably as follows: the feeding ratio of the distilled water to the ion exchange adsorption resin in the step (1) is 20-100 mL: 2g of the total weight. In the step (2), the solvent of the 2-methylimidazole solution is deionized water, and the feeding ratio of the deionized water to the 2-methylimidazole is 30 mL: 0.5-3 g; the oxygen isolation condition is that nitrogen or inert gas is introduced into the reaction system. In the step (3), the solvent of the cobalt acetate solution is deionized water, and the feed ratio of the deionized water to the cobalt acetate is 30 mL: 1.5-3 g.

The staged reaction process in the microwave reactor in the step (2) is as follows: under the condition of constant temperature, the set power is 200W, the reaction temperature is 60-80 ℃, and the reaction time is 5-20 min. The staged reaction process in the microwave reactor in the step (3) is as follows: under the condition of constant temperature, the set power is 600-800W, the reaction temperature is 100-105 ℃, and the reaction time is 40-60 min.

Further, the reaction mechanism for preparing the core-shell structure nanocomposite resin Co-MOF-D113-1 in the embodiment is as follows:

Co-MOF is used because of its Co-N moiety, high nitrogen content and large specific surface area. The Co-MOF is assembled on the surface through a layer-by-layer self-assembly process, D113, a cobalt acetate solution and 2-MI are mixed for multiple times to form a Co-MOF-D113-1 compound, and organic ligands of the Co-MOF interact with D113 through strong electrostatic attraction, so that the Co-MOF is immobilized on the D113. The carboxyl groups of D113 in water are negatively charged, while the 2-MI in water is positively charged, and when the 2-MI is deposited on the surface of D113, electrostatic attraction is generated. During the initial assembly of 2-MI, the adsorption rate was faster, a relatively constant adsorption value was observed at 15min, and during the subsequent cobalt acetate assembly, it took about 2h to reach the adsorption value, indicating that the organic ligands and metal ions of Co-MOF were assembled by covalent bonds. The Co-MOF-D113-1 nano composite resin is a layer-by-layer self-assembly of D113 as parent material, 2-methylimidazole and cobalt acetate, and the special functional group connected with the above-mentioned material and Cu ²⁺ And realizing adsorption. It is a novel high-performance adsorption material developed following ion exchange resin and ion exchange fiber.

The mechanism of the preparation process of the core-shell structure nano composite resin Co-MOF-D113-1 is as follows:

(1) referring to the schematic of FIG. 2, combining D113 with 2-MI yields 2-MI-D113:

(2)2-MI-D113 grafted on the surface of D113 and cobalt acetate form Co-MOF to coat on the surface of D113 when reacting with cobalt acetate solution to form Co-MOF-D113-1.

To further demonstrate the above reaction mechanism, this example performed IR spectroscopy on the resin before and after the reaction, and the results are shown in FIG. 3. D113 is 3000-3500 cm ^-1 Absorption in the range of 1714cm, caused by stretching vibration of OH ^-1 Is a characteristic absorption peak of C ═ O, 1544cm ^-1 And 1412cm ^-1 Absorption peaks due to antisymmetric and symmetric vibration of-COOH, respectively; 2-MI is 1113cm ^-1 The absorption peak of (a) is caused by the symmetric stretching of the imidazole ring; co (AC) ₂ The carboxyl group antisymmetry and symmetric absorption peak of (2) are shifted slightly to the higher wavenumber direction than that of D113, because Co ²⁺ The presence of-O coordination bonds causes an energy increase of 513cm ^-1 Is Co ² ⁺ An absorption peak of an O coordinate bond. The infrared spectrum of Co-MOF-D113-1 synthesized by taking D113 as a carrier in a layer-by-layer self-assembly mode shows that the hydroxyl absorption band of D113 still exists, and comes from D113 and Co (AC) ₂ The anti-symmetry and the symmetric absorption peak of carboxyl in (1) are also detected, and in addition, the vibration absorption of C ═ O in the tertiary amide bond formed by combining D113 and 2-MI is 1630cm ^-1 Of Co ²⁺ Since the O coordinate bond is in a more complicated electronic environment, the vibration energy of the O coordinate bond is slightly shifted to a high wave number direction. The FTIR confirmed the chemical structure of Co-MOF-D113-1.

Example 3

In the embodiment, the core-shell structure nanocomposite resin Co-MOF-D113-1 is used for Cu ²⁺ In the separation and adsorption experiment, the specific adsorption process is as follows:

adding 30mg of Co-MOF-D113-1 into a 250mL iodine measuring flask, adding 25mL of 0.2mol/LHAc-NaAc buffer solution with the pH of 2-7 for swelling for 12h, and then adding 5mL of 2000ppm Cu ²⁺ And (3) oscillating and adsorbing the standard stock solution for 0-24 hours at the temperature of 15-35 ℃ by using a constant-temperature oscillator. Then, the iodine vial was taken out and filtered, and the filtrate was measured by ICP-OES and the amount of adsorption was calculated. The adsorption result shows that the composite resin is applied to Cu ²⁺ Has excellent selectivity and large adsorption capacity, the adsorption capacity can reach 326mg/g under the optimal condition, and the structure after adsorption is shown in figure 4.

The material can be applied to Cu in environment or food ²⁺ Adsorption of various types containing Cu ²⁺ In wastewater, Cu of various kinds ²⁺ The existing state can be identified and adsorbed by the Co-MOF-D113-1 nano composite resin to form complex ions or complexes.Adsorbed Cu ²⁺ The desorption can be 100 percent in a 2mol/L hydrochloric acid solution system. After repeating 10 times adsorption-desorption experiments, the nano composite resin is used for treating Cu ²⁺ The adsorption amount of (A) is still 87% or more of the first adsorption amount.

The single-layer self-assembly nano composite resin is obtained by analysis, has the screening effect of the pore size of the organic metal framework material on an adsorption object and the coupling effect according with the interaction between the functional groups on the surface of the material and electrons of the adsorption object, and the experimental result shows that the single-layer self-assembly nano composite resin has good adsorption effect on copper ions, is superior to the technical indexes of the prior art such as adsorption capacity, stability and the like, and realizes the synergistic effect of the composite material.

Example 4

In order to prove that the practical effect of the core-shell structure nanocomposite resin Co-MOF-D113-1 is provided in the above examples, Cu is used in the examples ²⁺ And carrying out practical demonstration on three dimensions of adsorption, heavy metal ion desorption and comparison. The specific experimental procedures and results are as follows:

experiment 1: cu ²⁺ And (4) performing adsorption experiments.

Taking 30mg of Co-MOF-D113-1 nano composite resin, swelling in 25ml of HAc-NaAc buffer solution in advance, adjusting the pH of the buffer solution to 2-7, and adding 5ml of LCu into the reaction system after 12 hours ²⁺ And (3) oscillating and adsorbing the solution (with the concentration of 500ppm) for 0-24 h at the temperature of 35 ℃. And then taking the filtrate in the reaction system to test the solution concentration by adopting ICP-OES. Calculating the composite resin pair Cu by using the formula (1) ²⁺ The amount of adsorption of (3).

Wherein Q is saturated adsorption amount (mg/g) and C ₀ And C _e The concentrations of metal ions in the solution before adsorption and at equilibrium (mg/mL), m the weight of the resin (g) and V the total volume of the solution (mL) were measured.

Cu at various pH conditions ²⁺ The adsorption amount is shown in FIG. 5. Cu at various adsorption time conditions ²⁺ The adsorption amount is shown in FIG. 6.

From FIG. 5, the pH vs. Co-MOF-D1 can be seen13-1 adsorption of Cu ²⁺ Has a great influence on the adsorption amount of Cu ²⁺ As a common heavy metal ion, its stability is affected by the pH of the solution. And the composite material has adsorption sites in D113 and Co-MOF, and is influenced by the coupling adsorption of the two. The D113 resin is cation exchange resin with carboxylic acid group (-COOH) on the acrylic acid copolymer with macroporous structure, and the effective functional group is carboxyl. And the pKa of the carboxylic acid is between 2 and 5, when the pH is<5, D113 resin vs. Cu ²⁺ The amount of adsorption of (2) slowly increases because of H in the solution ⁺ The ion concentration is higher, the effective adsorption sites on the surface of the resin are protonated, and H in the solution is simultaneously ⁺ Ions with Cu ²⁺ Competitive adsorption, resulting in Cu at low pH ²⁺ The amount of adsorption of (3) is not high. And pH is>5 th case resin to Cu ²⁺ The adsorption amount of (A) is slowly increased, and Co-MOF and Cu are ²⁺ Better coordination bonding exists among the components, because the unique pore structure of Co-MOF is easier to adsorb Cu ²⁺ The coupling adsorption between the two is carried out until the pH value reaches about 5.5 and the maximum adsorption capacity is reached, the temperature is 35 ℃, the pH value is 6, and the adsorption time is 24h under the condition that the Cu is adsorbed ²⁺ The adsorption amount of (A) was 326 mg/g.

As can be seen from fig. 6, the adsorption amount varies with the adsorption time. The adsorption rate was faster at the beginning of adsorption, but gradually decreased to the adsorption equilibrium as adsorption proceeded. This is because Cu is adsorbed at the beginning ²⁺ The concentration in the solution is higher, the concentration on the Co-MOF-D113-1 is lower and is far away from the equilibrium state, so the mass transfer driving force is large, and moreover, the Co-MOF-D113-1 has enough adsorption sites, so the adsorption can be rapidly carried out along with the adsorption. Cu in liquid phase ²⁺ Decreased concentration of Cu on Co-MOF-D113-1 ²⁺ The adsorption driving force is reduced, and meanwhile, the adsorption sites on the Co-MOF-D113-1 are gradually reduced, so that the adsorption rate is gradually reduced until the equilibrium is reached.

Experiment 2: and (5) carrying out heavy metal ion desorption experiments.

And (3) collecting all the composite resins after the adsorption experiment, repeatedly washing the composite resins with deionized water, drying the composite resins, adding the dried composite resins into a 30mL iodine vial with 1-3 mol/L hydrochloric acid for imbibition, and performing oscillation desorption for 24 hours at the temperature of 35 ℃. And then taking the filtrate in the reaction system to test the solution concentration by adopting ICP-OES. The adsorption-desorption experiment was repeated for a total of 10 cycles, and the adsorption rate and desorption rate were calculated separately from the first time. The adsorption and desorption rates at each cycle number are shown in fig. 7.

In the formula, C _d : equilibrium concentration of metal ions in the desorption solution (mg/mL); v _d : volume of desorption solution (mL); c ₀ ，C _e And V is as above.

The composite resin adsorbing the copper ions is subjected to oscillation desorption in 1-3 mol/L hydrochloric acid solution, and the adsorbed copper ions can be 100% desorbed by 2mol/L hydrochloric acid. As can be seen from FIG. 4, the pair of Co-MOF-D113-1 to Cu ²⁺ After the adsorption-desorption experiment is repeatedly circulated for 10 times, the composite resin is used for treating Cu ²⁺ The adsorption amount of (A) is still more than 87% of the first adsorption amount, and the desorption rate is kept at 93%.

The core-shell structure nano composite resin Co-MOF-D113-1 prepared by the method is applied to copper-containing wastewater, and the composite resin is used for Cu ²⁺ The adsorption rate of (2) is 98%.

Experiment 3: and (6) preprocessing and comparing.

The microwave reaction is directly carried out without pretreatment to prepare the composite resin.

Adding the resin into a 2-methylimidazole solution, wherein the feeding ratio of deionized water to 2-methylimidazole is 30 mL: 0.5-3 g, carrying out staged reaction in a microwave reactor under the condition of oxygen isolation, and introducing nitrogen or inert gas into a reaction system:

under the condition of constant temperature, setting the power to be 200W, the reaction temperature to be 60-80 ℃, and the reaction time to be 5-20 min; under the condition of constant temperature, the set power is 600-800W, the reaction temperature is 100-105 ℃, and the reaction time is 40-60 min. And taking out the composite resin, repeatedly washing with absolute ethyl alcohol and deionized water, carrying out suction filtration, and drying to obtain the Co-MOF-D113-1 nano composite resin.

Experiment 1 was repeated with this composite resin to obtain an adsorbed amount of only 167 mg/g. This is because the pretreatment process can fully extend the internal structure of the resin, expose the functional groups on the external surface, increase the reaction probability, and increase the reaction rate.

As can be seen from the above examples, the present application has the following effects: combining macro and micro size materials to form nanometer composite material with excellent performance; secondly, the reaction process is simple and convenient, and is green; the Co-MOF-D113-1 material has a novel structure and high research value; the adsorption effect of heavy metal ions is superior to that of the prior art. The Co-MOF-D113-1 material has good adsorption stability and reusability, and can be applied to adsorption and purification of heavy metal ions in water.

Example 5

To demonstrate the selectivity of Co-MOF-D113-1 nanocomposite resin for copper ion adsorption, a mixed ion solution (containing Cu) of the same concentration was used ²⁺ 、Fe ²⁺ 、Zn ²⁺ 、Co ²⁺ 、Cd ²⁺ 、Mg ²⁺ ) Experiment 1 of example 4 was repeated instead of the copper ion solution, and measured for Cu ²⁺ The adsorption capacity is 315mg/g, and the adsorption capacity of other ions is less than 25 mg/g. This example demonstrates that the Co-MOF-D113-1 nanocomposite resin has good selective adsorption of copper ions. The mixed ions simultaneously existing in the conventional copper-containing electroplating wastewater are Fe ²⁺ 、Zn ²⁺ 、Co ²⁺ 、Cd ²⁺ 、Mg ²⁺ And the core-shell structure nano composite resin Co-MOF-D113-1 has good application prospect in copper-containing wastewater treatment.

It should be understood that the present invention is described by way of embodiments, and the embodiments are only provided for enabling technical solutions proposed by the claims of the present invention to achieve clear and complete descriptions, that is, explanations of the claims, so that when judging whether the technical solutions described in the present specification are sufficiently disclosed, the core meanings of the solutions defined by the claims should be fully considered, and other technical problems that are irrelevant to the solution of the core technical problems proposed by the embodiments are necessarily present in the description, and the corresponding technical features and technical solutions are not referred to in the present embodiment, but belong to unnecessary technical features, so that reference may be made to implicit disclosures, and those skilled in the art can fully combine the prior art with the common general knowledge to achieve the purposes, and therefore, no detailed description is necessary.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

Claims

1. A core-shell structure nano composite resin is characterized in that: the chemical formula of the core-shell structure nano composite resin is [ Co (MI) ] ₂ ] _n @ D113, the structure of the hybrid part is an organic framework compound ZIF-67, MI is 2-methylimidazole, n is a positive integer which is not zero, and the carrier D113 is hydrogen-type acrylic acid copolymerized macroporous resin and is marked as Co-MOF-D113-1;

and D113 is used as a matrix, dimethylimidazole and cobalt acetate are used as precursors of the D113, and the core-shell structure nano composite resin is synthesized by adopting an autonomous assembly method:

the preparation method of the core-shell structure nano composite resin Co-MOF-D113-1 comprises the following steps,

(1) pretreatment of raw materials: soaking and swelling the ion exchange adsorption resin D113 in distilled water for more than 24 hours, and washing and filtering the ion exchange adsorption resin with deionized water to obtain pretreated resin;

(2) preparation of 2-MI/D113: adding the pretreated resin prepared in the step (1) into a 2-methylimidazole solution, carrying out staged reaction in a microwave reactor under an oxygen-isolated condition, repeatedly washing products with absolute ethyl alcohol and deionized water respectively after the reaction is finished, carrying out suction filtration and drying to obtain 2-MI/D113 resin;

2. The core-shell structure nanocomposite resin according to claim 1, characterized in that: the feeding ratio of the distilled water to the ion exchange adsorption resin is 20-100 mL: 2g of the total weight.

3. The core-shell structure nanocomposite resin according to claim 1, characterized in that: in the step (2),

the solvent of the 2-methylimidazole solution is deionized water, and the feeding ratio of the deionized water to the 2-methylimidazole is 30 mL: 0.5-3 g;

the oxygen isolation condition is that nitrogen or inert gas is introduced into the reaction system.

4. The core-shell structure nanocomposite resin according to claim 1, characterized in that: in the step (3), the step (c),

the cobalt acetate solution solvent is deionized water, and the feed ratio of the deionized water to the cobalt acetate is 30 mL: 1.5-3 g.

5. The core-shell structure nanocomposite resin according to claim 1, characterized in that: the staged reaction processes in the microwave reactor in the step (2) and the step (3) are respectively as follows:

under the condition of constant temperature, setting the power to be 200W, the reaction temperature to be 60-80 ℃ and the reaction time to be 5-20 min;

under the condition of constant temperature, the set power is 600-800W, the reaction temperature is 100-105 ℃, and the reaction time is 40-60 min.

6. The application of the core-shell structure nano composite resin according to claim 1, which is characterized in that: the nano composite resin is used for treating metal ions Cu ²⁺ Has selective adsorption.

7. Use according to claim 6, characterized in that: the nano composite resin is applied to Cu in environment or food ² ⁺ Adsorption of (3).

8. Use according to claim 6, characterized in that: adsorbed Cu ²⁺ 100 percent of desorption is achieved in a 2mol/L hydrochloric acid solution system.

9. Use according to claim 6, characterized in that: after repeated circulation for 10 times of adsorption-desorption, the nano composite resin is used for treating Cu ²⁺ The adsorption amount of (A) is still 87% or more of the first adsorption amount.