Preparation method of palladium ion selective separation imprinted nanofibers based on electrospinning

Abstract

The present invention discloses a method for preparing palladium ion selective separation imprinted nanofibers based on electrospinning, which comprises the following steps: (1) mixing an imprinted functional monomer, sodium chloropalladate, a solvent, an electrospinning polymer monomer and an initiator, and then performing a polymerization reaction; the imprinted functional monomer comprises allylthiourea; (2) using the product obtained in step (1) to perform electrospinning to obtain nanofibers; (3) washing the nanofibers obtained in step (2) to remove palladium ions, thereby obtaining palladium ion selective separation imprinted nanofibers. The present invention also discloses palladium ion selective separation imprinted nanofibers obtained using the above method and their application in palladium ion selective separation. The present invention applies electrospinning technology to the preparation of palladium ion selective separation imprinted nanofibers, thereby achieving efficient and specific separation of palladium ions.

Description

Technical Field

[0001] The present invention belongs to the field of materials, and in particular relates to a method for preparing palladium ion selective separation imprinted nanofibers based on electrospinning. Background Art

[0002] Due to its excellent plasticity, stability, and catalytic activity, palladium is widely used in the petroleum, chemical, pharmaceutical, electronics, and chemical catalyst industries. For example, it serves as a primary catalyst in catalysis. It also forms alloys with gold, silver, copper, ruthenium, and iridium to enhance their strength, hardness, and resistivity, enabling its use in the manufacture of precision components. Palladium is expensive, costing up to 420,000 yuan per kilogram. Therefore, recovering palladium from palladium-containing waste is essential. Currently, the primary sources for palladium recovery include spent catalysts and electronic component scraps.

[0003] In the existing technology, the main methods for recovering palladium from waste include pyrolysis and wet methods. Pyrolysis is usually used to recover palladium from waste materials with low palladium content, and includes smelting, metal capture, chlorine volatilization, etc. Pyrolysis has a high recovery rate, but usually requires high-temperature operating conditions, high energy consumption, special equipment, and may produce toxic waste residue or exhaust gas. The wet recovery process includes two stages: dissolution and refining. It usually requires pre-enrichment before leaching. After leaching, the palladium needs to be separated. Separation methods include solvent extraction, precipitation, metal replacement, ion exchange, etc. Extraction methods have good selectivity, but require the use of organic solvents, which pollute the environment, and have high operating costs and complex processes. Precipitation methods require the use of chemical reagents, a long process cycle, and high costs. Metal replacement methods have a faster reaction and a higher recovery rate, but the reduced precipitate is easily contaminated by the replacement agent. Ion exchange methods have poor selectivity and are not suitable for the specific separation of palladium. Therefore, the development of palladium recovery and separation methods that take into account recovery rate, selectivity, cost, and environmental benefits is an important issue.

[0004] Molecular Imprinting Technology (MIT) is a technology that uses molecularly imprinted polymers to simulate the interactions between enzymes and substrates or antibodies and antigens to specifically recognize template molecules. Through the interaction between the template and the functional groups on the monomers, monomers self-assemble around the template molecule to form a molecularly imprinted polymer (MIP). The template is then partially or completely removed, leaving behind a cavity that is complementary to the template in size and shape. The resulting cavity can serve as a selective binding site for the template molecule. The application of molecular imprinting technology is expected to solve the problem of efficient and selective separation of palladium ions; however, existing molecularly imprinted materials are basically in the form of particles or even powders, which have large flow resistance during flow and are not conducive to practical industrial applications. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing palladium ion selective separation imprinted nanofibers based on electrospinning, which solves the problem of specific separation in palladium ion recovery.

[0006] The specific technical solutions are as follows:

[0007] One of the objects of the present invention is to provide a method for preparing palladium ion selective separation imprinted nanofibers based on electrospinning, which comprises the following steps:

[0008] (1) mixing an imprinting functional monomer, chloropalladium salt, a solvent, an electrospinning polymer monomer, and an initiator, and then performing a polymerization reaction; the imprinting functional monomer comprises allylthiourea;

[0009] (2) using the product obtained in step (1) to perform electrospinning to obtain nanofibers;

[0010] (3) Washing the nanofibers obtained in step (2) to remove the palladium ions and obtain palladium ion selective separation imprinted nanofibers.

[0011] Wherein, the palladium ion refers to the divalent palladium ion Pd 2+ ; Chloropaldalate refers to tetrachloropalladate.

[0012] In the present invention, the imprinted functional monomer and PdCl4 2- Forming a functional monomer-template complex; under the action of the initiator, the imprinted functional monomer and the electrospinning polymer monomer undergo polymerization to generate a polymer soluble in the solvent, which is then prepared into nanofibers by electrospinning. 2- It has been embedded into the surface of nanofibers. Then wash the embedded PdCl4 2- Remove it to leave an adsorption space.

[0013] Traditional imprinted materials typically exist in granular or even powder form, which presents significant flow resistance and is not conducive to practical industrial applications. The present invention overcomes this problem by applying electrospinning technology to the preparation of imprinted materials, resulting in fibrous imprinted materials. Furthermore, the majority of adsorption pores in the imprinted materials prepared by the present invention are located on the fiber surface, resulting in a faster adsorption rate.

[0014] Furthermore, in step (1): the chloropalladate is sodium chloropalladate.

[0015] Furthermore, in step (1), the molar ratio of allylthiourea to chloropalladate is preferably (2-4):1.

[0016] Furthermore, in step (1), the ratio of the imprinting functional monomer to the electrospinning polymer monomer is (0.2-0.6) g:1 mL.

[0017] Furthermore, in step (1): the electrospinning polymer monomer is at least one of acrylonitrile, vinylidene fluoride, and para-chloromethylstyrene.

[0018] Furthermore, in step (1): the solvent is at least one of N,N-dimethylformamide and dimethyl sulfoxide.

[0019] Furthermore, in step (1): the initiator is at least one of azobisisobutyronitrile and azobisisoheptanenitrile.

[0020] Furthermore, in step (1), the volume ratio of the solvent to the electrospinning polymer monomer is preferably (5-20):1.

[0021] Furthermore, in step (1), the polymerization reaction is preferably carried out at 50-90° C. for 4-48 hours, more preferably at 60-80° C. for 8-15 hours.

[0022] Furthermore, in step (1): after mixing the components, ultrasonic treatment is preferably performed, preferably for 10 to 30 minutes.

[0023] Furthermore, in step (2): the electrospinning conditions are preferably room temperature, a voltage of 15 to 18 kV, a flow rate of 0.10 to 0.30 mL / min, and a receiving distance of 15 to 18 cm.

[0024] Furthermore, in step (3), the nanofibers are washed with a mixed solution of thiourea and hydrochloric acid. In the washing solution, the thiourea concentration is preferably 4-7 mol / L, and the hydrochloric acid concentration is preferably 4-8 mol / L.

[0025] After washing to remove the palladium ions, the nanofibers are dried, preferably in a vacuum drying oven at 30-70° C. for 4-24 hours.

[0026] The second object of the present invention is to provide a palladium ion selective separation imprinted nanofiber obtained using the above preparation method.

[0027] The third object of the present invention is to provide the application of the above-mentioned palladium ion selective separation imprinted nanofiber in palladium ion selective separation. The nanofiber material of the present invention leaves behind a specific PdCl4 2- Adsorption vacancies realizes the PdCl4 2- Highly efficient and specific separation.

[0028] The beneficial effects of the present invention are as follows:

[0029] The present invention applies electrospinning technology to the preparation of palladium ion selective separation imprinted nanofibers, achieving efficient and specific separation of palladium ions. The present invention applies electrospinning technology to the preparation of imprinted materials to obtain fibrous imprinted materials, overcoming the problem of high flow resistance of traditional granular or powdered imprinted materials, and is more suitable for industrial applications. The imprinted materials prepared by this method have a high affinity for PdCl4 2- The maximum adsorption capacity can reach 537mg / g, and the adsorption equilibrium time is within 25min. 2- The palladium ion selective separation imprinted nanofiber of the present invention can be used to specifically recover PdCl4 from waste catalysts, electronic device scraps and other wastes. 2- . BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a SEM image of the palladium ion selective separation imprinted nanofibers prepared in Example 1;

[0031] Figure 2 This is the infrared spectrum of the palladium ion selective separation imprinted nanofibers prepared in Example 1;

[0032] Figure 3 This is the SEM image of the palladium ion selective separation imprinted nanofiber after adsorption of palladium ions in Example 1;

[0033] Figure 4 This is the infrared spectrum of the palladium ion selective separation imprinted nanofiber after adsorbing palladium ions in Example 1. DETAILED DESCRIPTION

[0034] The principles and features of the present invention are described below with reference to examples. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0035] Example 1

[0036] 1. Preparation of chromium ion selective separation imprinted nanofibers, the steps are as follows:

[0037] (1) Using allylthiourea and sodium chloropalladate as raw materials, 0.35 g of allylthiourea and 0.294 g of sodium chloropalladate were weighed (controlling the molar ratio of allylthiourea to chloropalladate to be 3:1), and then a mixed solution of 10 mL of N,N-dimethylformamide, 1.0 mL of acrylonitrile, and 0.1 g of azobisisobutyronitrile was added, ultrasonicated at room temperature for 10 min, and then reacted at 80°C for 12 h to allow polymerization to occur;

[0038] (2) using the product obtained in step (1) to perform electrospinning, the operating conditions are: at room temperature, voltage of 16 kV, flow rate of 0.15 mL / min, receiving distance of 15 cm, to obtain nanofibers;

[0039] (3) The nanofibers obtained in step (2) were thoroughly washed with a mixed solution of 6 mol / L thiourea and 6 mol / L HCl to remove the palladium ions, and then placed in a vacuum drying oven at 50° C. and dried for 8 h to obtain ion-imprinted nanofibers with specific selectivity for palladium ions.

[0040] The SEM images of the obtained ion-imprinted nanofibers are shown in Figure 2. Figure 1 As shown, the infrared spectrum is Figure 2 shown.

[0041] The adsorption of PdCl4 by the prepared imprinted nanofibers was systematically investigated through static adsorption experiments, including adsorption kinetics and isotherm experiments. 2- The adsorption performance of PdCl4 2- The maximum adsorption capacity is 537 mg / g, and the adsorption equilibrium time is 25 min.

[0042] 2. The ion-imprinted nanofibers obtained by the above method were used to selectively recover palladium ions from the waste catalyst leachate, and the composition is shown in Table 1.

[0043] Table 1

[0044] Element <![CDATA[Pd 2+ ]]> <![CDATA[Al 3+ ]]> <![CDATA[K + ]]> <![CDATA[Na + ]]> <![CDATA[Ca 2+ ]]> <![CDATA[Mg 2+ ]]> Content (mg / L) 36.3 258503 243.4 4353 784.3 642.8

[0045] The experimental method is as follows: 2.0 g of ion-imprinted nanofibers prepared by the above method were weighed and placed in an adsorption column with a diameter of 10 mm and a height of 100 mm. The flow rate was controlled at 0.5 mL / min by a peristaltic pump, and the sample volume was 1000 mL. After the water sample was treated, the composition of the effluent was shown in Table 2. The SEM image of the ion-imprinted nanofibers after adsorption is shown in Table 2. Figure 3 As shown, the infrared spectrum is Figure 4 shown.

[0046] Table 2

[0047] Element <![CDATA[Pd 2+ ]]> <![CDATA[Al 3+ ]]> <![CDATA[K + ]]> <![CDATA[Na + ]]> <![CDATA[Ca 2+ ]]> <![CDATA[Mg 2+ <!-- 3 -->]]> Content (mg / L) 0 258487 238.5 4333 779.4 634.4

[0048] Then, 5 mL of a mixed solution of 6 mol / L thiourea and 6 mol / L HCl was used as the desorption solution to determine the Pd 2+ The concentration is 7.1g / L, of which Pd 2+ The content exceeds 98.9%.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing palladium ion selective separation imprinted nanofibers based on electrospinning, characterized in that: The steps include: (1) mixing an imprinting functional monomer, chloropalladium salt, a solvent, an electrospinning polymer monomer, and an initiator, and then performing a polymerization reaction; the imprinting functional monomer comprises allylthiourea; and the electrospinning polymer monomer is at least one of acrylonitrile, vinylidene fluoride, and p-chloromethylstyrene; (2) using the product obtained in step (1) to perform electrospinning to obtain nanofibers; (3) Washing the nanofibers obtained in step (2) to remove the palladium ions and obtain palladium ion selective separation imprinted nanofibers.

2. The preparation method according to claim 1, characterized in that In step (1): the chloropalladate is sodium chloropalladate.

3. The preparation method according to claim 1, characterized in that In step (1), the molar ratio of allylthiourea to chloropalladate is (2-4):

1.

4. The preparation method according to claim 1, characterized in that In step (1), the ratio of the imprinting functional monomer to the electrospinning polymer monomer is (0.2-0.6) g:1 mL.

5. The preparation method according to claim 1, characterized in that In step (1): The solvent is at least one of N,N-dimethylformamide and dimethyl sulfoxide; The initiator is at least one of azobisisobutyronitrile and azobisisoheptanenitrile.

6. The preparation method according to claim 1, characterized in that In step (1), the volume ratio of the solvent to the electrospinning polymer monomer is (5-20):

1.

7. The preparation method according to claim 1, characterized in that In step (1), the polymerization reaction is carried out at 50-90° C. for 4-48 hours.

8. The preparation method according to claim 1, characterized in that In step (3): the nanofibers are washed with a mixed solution of thiourea and hydrochloric acid.

9. A palladium ion selective separation imprinted nanofiber based on electrospinning, obtained using the preparation method according to any one of claims 1 to 8.

10. Use of the electrospinning-based palladium ion selective separation imprinted nanofiber according to claim 9 in palladium ion selective separation.

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