A porous cof adsorbent with high efficiency for enriching palladium and a preparation method and application thereof

Abstract

The present application relates to a kind of high-efficiency enrichment porous COF adsorbent of palladium and its preparation method and application, belong to composite material technical field.The high-efficiency enrichment porous COF adsorbent of palladium of the present application is recorded as COF-BcTd, and is generated by 1,3,5-benzene triformyl chloride and 1,3,4-thiadiazole-2,5 diamine acylation reaction, its structural formula is:the high-efficiency enrichment porous COF adsorbent of palladium can be used to efficiently and selectively adsorb enrichment palladium ion from solution, and has strong cyclic regeneration capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of porous COF adsorbent of high-efficiency enrichment palladium and its preparation method and application, belong to composite material technical field. BACKGROUND

[0002] Palladium belongs to platinum group metals, and has similar chemical properties with platinum, rhodium and other metals, and is widely used. For example, in the electronics industry, palladium is widely used to manufacture multilayer ceramic capacitors and other electronic components; in the automotive industry, palladium is a key component in the automobile exhaust catalytic converter. With the continuous development of science and technology industry, the demand for palladium in various industries is increasing. If excessive reliance on primary palladium ore supply, the palladium supply chain will be severely impacted. Recycling of palladium-containing secondary resources can not only effectively alleviate the pressure of primary ore mining, but also ensure the continuous access to palladium resources in various industries. Therefore, it is of great economic benefit and strategic significance to recover palladium from palladium-containing waste materials / waste liquids and other secondary resources.

[0003] Currently, high-concentration palladium-containing solutions are usually treated by direct reduction method, but this method is not suitable for low-concentration palladium-containing solutions. Adsorption method is applied to the separation and enrichment of low-concentration noble metals due to its high efficiency. The common resin, silica gel, biomass and other adsorption materials have the disadvantages of low adsorption capacity, poor selectivity, high cost and complex process.

[0004] The existing covalent organic framework (COFs) has a large number of active groups distributed on the surface, and has excellent adsorption performance and is easy to modify. However, the existing COFs materials for adsorbing metal palladium still have a series of technical problems, such as high synthesis cost due to the high price of some monomers used for synthesizing COFs; insufficient structural stability due to the change of COFs structure in strong acid or strong base solution; poor adsorption selectivity due to competitive adsorption in actual solution. SUMMARY

[0005] In view of the poor adsorption performance of the existing covalent organic framework COFs adsorption material for low-concentration palladium ions, the present application provides a kind of porous COF adsorbent of high-efficiency enrichment palladium and its preparation method and application. The porous COF adsorbent of high-efficiency enrichment palladium is generated by acylation reaction of 1,3,5-benzene tricarboxylic chloride and 1,3,4-thiadiazole-2,5 diamine, and can be used for high-efficiency selective adsorption of low-content palladium ions from solution, and has strong recycling ability.

[0006] A kind of porous COF adsorbent of high-efficiency enrichment palladium, the adsorbent is generated by acylation reaction of 1,3,5-benzene tricarboxylic chloride and 1,3,4-thiadiazole-2,5 diamine, and is recorded as adsorbent COF-BcTd, and its structural formula is:

[0007]

[0008] The preparation method of the high-efficiency porous COF adsorbent for enriching palladium, and the specific steps are as follows:

[0009] (1) 1,3,5-benzene tricarboxylic acid chloride and 1,3,4-thiadiazole-2,5 diamine are respectively stirred and dissolved in N,N-dimethylformamide solvent to obtain 1,3,5-benzene tricarboxylic acid chloride solution and 1,3,4-thiadiazole-2,5 diamine solution, and an equal volume of 1,3,5-benzene tricarboxylic acid chloride solution and 1,3,4-thiadiazole-2,5 diamine solution are mixed to obtain a mixed solution;

[0010] (2) The mixed solution is placed in a reaction kettle and stirred at a temperature of 60-80℃ for 12-36h, and after cooling to room temperature, solid-liquid separation is performed, the solid is sequentially washed with N,N-dimethylformamide and ethanol, and vacuum drying is performed to obtain the high-efficiency porous COF adsorbent for enriching palladium.

[0011] Preferably, in step (1), the solid-liquid ratio g:mL of 1,3,5-benzene tricarboxylic acid chloride to N,N-dimethylformamide in the 1,3,5-benzene tricarboxylic acid chloride solution is 1:60-70.

[0012] Preferably, in step (1), the solid-liquid ratio g:mL of 1,3,4-thiadiazole-2,5 diamine to N,N-dimethylformamide in the 1,3,4-thiadiazole-2,5 diamine solution is 1:90-110.

[0013] Preferably, in step (2), the reaction temperature is 60-80℃.

[0014] Preferably, in step (2), the reaction time is 12-36h.

[0015] The application of the high-efficiency porous COF adsorbent for enriching palladium in selectively adsorbing palladium ions in a solution.

[0016] Preferably, the content of palladium ions in the solution is 30-60mg / L.

[0017] The recycling and regeneration method of the high-efficiency porous COF adsorbent for enriching palladium: after adsorbing palladium, COF-BcTd is eluted with a desorption solution (40mL) composed of 1% concentrated hydrochloric acid and 10% thiourea for 20h, and then washed with deionized water for 3-4 times before drying.

[0018] The principle of the porous COF adsorbent for efficiently enriching palladium selectively adsorbing low-concentration palladium ions is that Pd(II) in the solution is chelated with the amide groups of the adsorbent COF-BcTd, and meanwhile, Pd(II) produces strong electrostatic adsorption and weak electrostatic adsorption with the C=S groups and C-N bonds of COF-BcTd, so that the adsorbent COF-BcTd realizes adsorption and enrichment of 50 mg / L palladium solution under the dual action of chelation and electrostatic adsorption.

[0019] The beneficial effects of the present application are:

[0020] (1) The porous COF adsorbent for efficiently enriching palladium has amide groups, C=S groups, C-N bonds and other functional groups, so that it has rich adsorption sites, can efficiently and selectively adsorb low-concentration palladium ions in the solution, and has strong recycling and regeneration capacity;

[0021] (2) The porous COF adsorbent for efficiently enriching palladium is a covalent organic framework adsorbent material prepared from an organic material with rich adsorption sites, and has larger pore volume and specific surface area and adsorbent stability;

[0022] (3) The adsorption rate of the porous COF adsorbent for efficiently enriching palladium to 50 mg / L palladium solution can reach 93.13%, and after four repetitions, the adsorption rate of palladium can also reach 88.70%. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 SEM image of the porous COF adsorbent for efficiently enriching palladium of Example 1;

[0024] Fig. 2 EDS image of the porous COF adsorbent for efficiently enriching palladium of Example 1;

[0025] Fig. 3 FT-IR image of the porous COF adsorbent for efficiently enriching palladium of Example 1;

[0026] Fig. 4 XPS image of the porous COF adsorbent for efficiently enriching palladium of Example 1 before and after adsorbing palladium ions;

[0027] Fig. 5 SEM image of the porous COF adsorbent for efficiently enriching palladium of Example 1 after adsorbing palladium ions;

[0028] Fig. 6 EDS image of the porous COF adsorbent for efficiently enriching palladium of Example 1 after adsorbing palladium ions. DETAILED DESCRIPTION

[0029] The present application will be further described in conjunction with the specific embodiments, but the scope of protection of the present application is not limited to the described content.

[0030] Embodiment 1: a method for preparing a porous COF adsorbent with high efficiency for enriching palladium, the specific steps are as follows:

[0031] (1) 1,3,5-benzene tricarboxylic acid chloride and 1,3,4-thiadiazole-2,5 diamine were respectively stirred and dissolved in N,N-dimethylformamide solvent to obtain 1,3,5-benzene tricarboxylic acid chloride solution and 1,3,4-thiadiazole-2,5 diamine solution, and an equal volume of 1,3,5-benzene tricarboxylic acid chloride solution and 1,3,4-thiadiazole-2,5 diamine solution were mixed to obtain a mixed solution; the solid-liquid ratio g:mL of 1,3,5-benzene tricarboxylic acid chloride to N,N-dimethylformamide in the 1,3,5-benzene tricarboxylic acid chloride solution was 1:65, and the solid-liquid ratio g:mL of 1,3,4-thiadiazole-2,5 diamine to N,N-dimethylformamide in the 1,3,4-thiadiazole-2,5 diamine solution was 1:100;

[0032] (2) The mixed solution was placed in a reaction kettle and stirred at a temperature of 70°C for 24h, and then cooled to room temperature for solid-liquid separation, and the solid was sequentially washed with N,N-dimethylformamide and ethanol, and vacuum dried to obtain a porous COF adsorbent with high efficiency for enriching palladium, which is recorded as adsorbent COF-BcTd; the reaction formula is:

[0033]

[0034] The SEM, EDS, FT-IR and XPS diagrams of the adsorbent COF-BcTd of this embodiment are shown in Figs. 1-4 , which is mainly composed of elements C, N, O and S, and the weight percentages of C, N, O and S are 59.66%, 20.22%, 10.71% and 9.41% respectively; in the FT-IR diagram, the energy band at 1098cm -1 corresponds to C-S-stretching vibration, the energy band at 1382cm -1 corresponds to C-N-stretching vibration, the spectrum band at 1662cm -1 is related to the stretching vibration of C=O of amide group CONH-, and the spectrum band at 1577cm -1 is related to the deformation vibration of amine group, indicating that the acylation reaction between 1,3,5-benzene tricarboxylic acid chloride and 1,3,4-thiadiazole-2,5 diamine is successful; through XPS analysis, the peak values in the spectrum diagram of COF-BcTd mainly come from C1s, N 1s, O 1s and S2p;

[0035] The selective adsorption performance of the porous COF adsorbent COF-BcTd with high efficiency for enriching palladium in this embodiment to palladium ions was determined:

[0036] The adsorbent COF-BcTd (40 mg) and the solution to be adsorbed (pH = 2.5, 10 mL) containing Pd (II) 50.57 mg / L, Li (I) 47.34 mg / L, Mg (II) 1.26 g / L, K (I) 2.48 mg / L, Na (I) 7.08 g / L, Al (III) 1.41 g / L, Ga (III) 41.96 mg / L were added into a 15 mL centrifuge tube at room temperature, and oscillated at a speed of 200 rpm for 20 h in a shaker. The adsorbent was centrifuged and the supernatant was obtained, and the residual concentration of the remaining metal ions in the supernatant was determined by ICP-OES;

[0037] It was calculated that the removal rate of Pd (II) was 71.19%, the removal rate of Li (I) was 0.02%, the removal rate of Mg (II) was 0%, the removal rate of K (I) was 0.02%, the removal rate of Na (I) was 0.01%, the removal rate of Al (III) was 0.01%, and the removal rate of Ga (III) was 0.06%;

[0038] It can be seen that the porous COF adsorbent COF-BcTd of the product of the embodiment has a strong selectivity for palladium ions for efficiently enriching palladium;

[0039] Performance determination of the adsorbent COF-BcTd for adsorbing palladium ions in the embodiment:

[0040] The adsorbent COF-BcTd (40 mg) and the Pd (II) solution (pH = 2.5, 10 mL, 50 mg / L) were added into a 15 mL centrifuge tube at room temperature, and oscillated at a speed of 200 rpm for 20 h in a shaker. The adsorbent was centrifuged and the supernatant was obtained;

[0041] The adsorbent COF-BcTd after adsorbing palladium ions was subjected to SEM, EDS and XPS analysis, and the results are shown in Figs. 4-6 , Fig. 4 The characteristic peak of Pd was found in (XPS), and the content of Pd was calculated to be 33.43% from Fig. 5 It can be seen that the distribution state of Pd on the adsorbent is uniform distribution; Fig. 6

[0042] ​The concentration of residual palladium ions in the supernatant was determined by ICP-OES to be 3.09 mg / L, the adsorption capacity of the adsorbent COF-BcTd for Pd(II) was 41.95 mg / g, and the adsorption efficiency was 93.13%; after adsorbing palladium ions, the COF-BcTd was eluted with a desorption solution (40 mL) composed of 1% concentrated hydrochloric acid and 10% thiourea for 20 h; after centrifugation, the adsorbent was washed with distilled water until the solution was neutral, thereby completing the regeneration of the adsorbent COF-BcTd; after four repeated experiments, the adsorption rate of Pd(II) in the fourth adsorption was 88.70%.

[0043] Example 2: A preparation method of a porous COF adsorbent for efficient enrichment of palladium, the specific steps are as follows:

[0044] (1) 1,3,5-benzene tricarbonyl chloride and 1,3,4-thiadiazole-2,5 diamine were respectively stirred and dissolved in N,N-dimethylformamide solvent to obtain 1,3,5-benzene tricarbonyl chloride solution and 1,3,4-thiadiazole-2,5 diamine solution, and an equal volume of 1,3,5-benzene tricarbonyl chloride solution and 1,3,4-thiadiazole-2,5 diamine solution were mixed to obtain a mixed solution; the solid-liquid ratio g:mL of 1,3,5-benzene tricarbonyl chloride to N,N-dimethylformamide in the 1,3,5-benzene tricarbonyl chloride solution was 1:60, and the solid-liquid ratio g:mL of 1,3,4-thiadiazole-2,5 diamine to N,N-dimethylformamide in the 1,3,4-thiadiazole-2,5 diamine solution was 1:90;

[0045] (2) The mixed solution was placed in a reaction kettle and stirred at a temperature of 60°C for 12 h, and then cooled to room temperature for solid-liquid separation. The solid was sequentially washed with N,N-dimethylformamide and ethanol, and vacuum dried to obtain a porous COF adsorbent for efficient enrichment of palladium, which was recorded as adsorbent COF-BcTd; the reaction formula is as follows:

[0046] In this embodiment, the selective adsorption performance of the porous COF adsorbent COF-BcTd for palladium ions was determined as follows:

[0047] At room temperature, the adsorbent COF-BcTd (40 mg) and the adsorption solution (pH = 2.5, 10 mL) containing Pd(II) 50.57 mg / L, Li(I) 47.34 mg / L, Mg(II) 1.26 g / L, K(I) 2.48 mg / L, Na(I) 7.08 g / L, Al(III) 1.41 g / L, and Ga(III) 41.96 mg / L were added to a 15 mL centrifuge tube, and the mixture was oscillated at a speed of 200 rpm for 20 h in an oscillation machine; the adsorbent was centrifuged and the supernatant was obtained, and the residual concentration of residual metal ions in the supernatant was determined by ICP-OES;

[0048] The removal rate of Pd(II) is 71.05%, the removal rate of Li(I) is 0.02%, the removal rate of Mg(II) is 0%, the removal rate of K(I) is 0.02%, the removal rate of Na(I) is 0.01%, the removal rate of Al(III) is 0.02%, and the removal rate of Ga(III) is 0.07%;

[0049] It can be seen that the porous COF adsorbent COF-BcTd of the product of the embodiment has strong selectivity for palladium ions, and efficiently enriches palladium.

[0050] Performance determination of the adsorbent COF-BcTd for adsorbing palladium ions:

[0051] The adsorbent COF-BcTd (40 mg) and the Pd(II) solution (pH = 2.5, 10 mL, 50 mg / L) were added to a 15 mL centrifuge tube at room temperature, and oscillated at a speed of 200 rpm in a shaking machine for 20 h; the adsorbent was centrifuged and the supernatant was obtained;

[0052] The remaining palladium ion concentration in the supernatant was determined by ICP-OES to be 4.29 mg / L, the adsorption capacity of the adsorbent COF-BcTd for Pd(II) was 45.75 mg / g, and the adsorption efficiency was 90.47%; the COF-BcTd after adsorbing palladium ions was eluted with a desorption solution (40 mL) composed of 1% concentrated hydrochloric acid and 10% thiourea for 20 h; after centrifugation, the adsorbent was washed with distilled water until the solution was neutral, and the regeneration of the adsorbent COF-BcTd was completed; after four repeated experiments, the adsorption rate of Pd(II) in the fourth adsorption was 87.13%.

[0053] Embodiment 3: A preparation method of a porous COF adsorbent for efficiently enriching palladium, the specific steps are as follows:

[0054] (1) 1,3,5-benzene tricarbonyl chloride and 1,3,4-thiadiazole-2,5 diamine were respectively stirred and dissolved in N,N-dimethylformamide solvent to obtain 1,3,5-benzene tricarbonyl chloride solution and 1,3,4-thiadiazole-2,5 diamine solution, and an equal volume of 1,3,5-benzene tricarbonyl chloride solution and 1,3,4-thiadiazole-2,5 diamine solution were mixed to obtain a mixed solution; the solid-liquid ratio g:mL of 1,3,5-benzene tricarbonyl chloride to N,N-dimethylformamide in the 1,3,5-benzene tricarbonyl chloride solution is 1:70, and the solid-liquid ratio g:mL of 1,3,4-thiadiazole-2,5 diamine to N,N-dimethylformamide in the 1,3,4-thiadiazole-2,5 diamine solution is 1:110;

[0055] (2) The mixed solution was placed in a reaction kettle and stirred at a temperature of 80°C for 36h. After cooling to room temperature, the solid-liquid separation was performed, and the solid was washed with N,N-dimethylformamide and ethanol in sequence, and vacuum dried to obtain the porous COF adsorbent with high efficient enrichment of palladium, recorded as adsorbent COF-BcTd; the reaction formula is as follows:

[0056] The selective adsorption performance of the porous COF adsorbent COF-BcTd with high efficient enrichment of palladium to palladium ions was determined in this example.

[0057] The adsorbent COF-BcTd (40mg) and the solution to be adsorbed (pH=2.5, 10mL) containing Pd(II) 50.57mg / L, Li(I) 47.34mg / L, Mg(II) 1.26g / L, K(I) 2.48mg / L, Na(I) 7.08g / L, Al(III) 1.41g / L, Ga(III) 41.96mg / L were added into a 15mL centrifuge tube at room temperature, and oscillated at a speed of 200rpm for 20h in a shaking machine. The adsorbent was centrifuged and the supernatant was obtained, and the residual concentration of the remaining metal ions in the supernatant was determined by ICP-OES.

[0058] It was calculated that the removal rate of Pd(II) was 71.01%, the removal rate of Li(I) was 0.03%, the removal rate of Mg(II) was 0.01%, the removal rate of K(I) was 0.02%, the removal rate of Na(I) was 0.01%, the removal rate of Al(III) was 0.01%, and the removal rate of Ga(III) was 0.08%;

[0059] It can be seen that the porous COF adsorbent BPD-POP with high efficient enrichment of palladium in the product of this example has a strong selectivity to palladium ions;

[0060] The performance of the adsorbent COF-BcTd in adsorbing palladium ions was determined in this example.

[0061] The adsorbent COF-BcTd (40mg) and the Pd(II) solution (pH=2.5, 10mL, 50mg / L) were added into a 15mL centrifuge tube at room temperature, and oscillated at a speed of 200rpm for 20h in a shaking machine. The adsorbent was centrifuged and the supernatant was obtained.

[0062] The concentration of the residual palladium ions in the supernatant was 3.23 mg / L, the adsorption capacity of the adsorbent COF-BcTd for Pd(II) was 41.81 mg / g, and the adsorption efficiency was 92.83%; the COF-BcTd after adsorbing palladium ions was eluted with a desorption solution (40 mL) composed of 1% concentrated hydrochloric acid and 10% thiourea for 20 h; after centrifugation, the adsorbent was washed with distilled water until the solution was neutral, thereby completing the regeneration of the adsorbent COF-BcTd; after four repeated experiments, the adsorption rate of Pd(II) in the fourth adsorption was 85.23%.

[0063] The specific embodiments of the present application are described in detail above, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A porous COF adsorbent highly enriched in palladium, characterized by: The adsorbent is acylated by 1,3,5-benzene tricarboxylic chloride and 1,3,4-thiadiazole-2,5 diamine to generate an adsorbent COF-BcTd, and the structural formula is as follows: 。 2. The method of claim 1, wherein the method of making the porous COF adsorbent for efficient palladium enrichment is characterized by, The specific steps are as follows: (1) 1,3,5-benzene tricarboxylic chloride and 1,3,4-thiadiazole-2,5 diamine are respectively stirred and dissolved in N,N-dimethylformamide solvent to obtain 1,3,5-benzene tricarboxylic chloride solution and 1,3,4-thiadiazole-2,5 diamine solution, and equal volumes of the 1,3,5-benzene tricarboxylic chloride solution and the 1,3,4-thiadiazole-2,5 diamine solution are mixed to obtain a mixed solution; (2) The mixed solution is placed in a reaction kettle, stirred at a temperature of 60-80°C for 12-36h, cooled to room temperature, and then solid-liquid separation is performed, the solid is sequentially washed with N,N-dimethylformamide and ethanol, and vacuum drying is performed to obtain the high-efficiency porous COF adsorbent rich in palladium.

3. The method of claim 2, wherein the method comprises: In step (1), the solid-liquid ratio g:mL of 1,3,5-benzene tricarboxylic chloride to N,N-dimethylformamide in the 1,3,5-benzene tricarboxylic chloride solution is 1:60-70.

4. The method of claim 2, wherein the method comprises: In step (1), the solid-liquid ratio g:mL of 1,3,4-thiadiazole-2,5 diamine to N,N-dimethylformamide in the 1,3,4-thiadiazole-2,5 diamine solution is 1:90-110.

5. The high-efficiency porous COF adsorbent rich in palladium of claim 1 is applied to selectively adsorb palladium ions in a solution.

6. The application according to claim 5, wherein the content of palladium ions in the solution is 30-60mg / L.

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