Ion covalent organic framework material, synthetic method thereof and application of ion covalent organic framework material in field of gold adsorption

Abstract

The invention discloses an ionic covalent organic framework material, a synthesis method thereof and application of the ionic covalent organic framework material in the field of gold adsorption, and belongs to the technical field of environmental protection. The preparation method comprises the following steps: taking trihydroxy phloroglucinol as a three-connection building block, and reacting the trihydroxy phloroglucinol with a two-connection building block of 5, 5 '-diamino-2, 2'-dipyridyl to obtain an imine covalent organic framework TPBPY-COF; the covalent organic framework is subjected to post modification, and an ion covalent organic framework im-TPBPY-COF is obtained; a gold adsorption capacity experiment shows that the ion covalent organic framework has a removal effect on AuCl4 <->; the ionic covalent organic framework disclosed by the invention is simple in synthesis method, low in cost and environment-friendly, realizes efficient recovery of AuCl4 <-> in a water body, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular relates to an ionic covalent organic framework material and a synthesis method thereof and an application in the field of gold adsorption. Background Art

[0002] With the rapid development of the electronics industry and the jewelry industry, the demand for gold is increasing. However, the reserves of gold ore are limited, the resources are increasingly depleted, and the mining cost is high. Therefore, recovering gold from gold-containing waste liquid has important economic and environmental significance. At the same time, a large number of discarded electronic products are released into the environment every year, and these electronic products contain a large amount of metals. Recovering gold from discarded electronic products is one of the feasible strategies to solve environmental pollution problems and alleviate the contradiction between gold supply and demand. In the process of processing discarded electronic products, gold is dissolved by strong acid to form AuCl4 - Anions exist. Traditional gold recovery methods such as chemical precipitation and ion exchange have problems such as complex operation, high cost and low efficiency. Ionic covalent organic framework refers to a covalent organic framework with ionic groups, which has the characteristics of pre-designability, high specific surface area, adjustable pore size, stable structure and other advantages. It uses electrostatic adsorption to break through the bottleneck of low adsorption efficiency. At present, there is relatively little research on the application of ionic covalent organic framework in the field of gold adsorption. Summary of the invention

[0003] The purpose of the present invention is to synthesize an ionic covalent organic framework through post-modification, and the material has good application prospects in the field of gold adsorption.

[0004] The technical solution of the present invention is as follows: an ionic covalent organic framework material, the preparation method of which specifically comprises the following steps:

[0005] 1) Solvothermal synthesis of covalent organic framework: trialdehyde ligand, ammonia ligand, solvent and catalyst are mixed, degassed by freeze-thaw cycle, vacuumed, and then reacted at 120°C for 3 days. The obtained reactant is centrifuged, the solid is collected, washed, and vacuum dried to obtain the covalent organic framework TPBPY-COF;

[0006] 2) Post-modification synthesis of ionic covalent organic framework: The covalent organic framework TPBPY-COF obtained in step 1), paraformaldehyde, solvent and catalyst are mixed, degassed by freeze-thaw cycle, vacuumized, and then reacted at 120°C.

[0007] After 12 hours, the obtained reaction product was centrifuged, the solid was collected, washed, and vacuum dried to obtain the ionic covalent organic framework im-TPBPY-COF.

[0008] In the above-mentioned method for preparing an ionic covalent organic framework, in step 1), the trialdehyde ligand is trihydroxyphloroglucinol, the ammonia ligand is 5,5'-diamino-2,2'-bipyridine, and the solvent is o-dichlorobenzene and N,N-dimethylacetamide.

[0009] In the above-mentioned method for preparing an ionic covalent organic framework, in step 1), the trialdehyde ligand: ammonia ligand: o-dichlorobenzene: N,N-dimethylacetamide = 0.2 mmol: 0.3 mmol: 1 ml: 3 ml.

[0010] In the above-mentioned method for preparing an ionic covalent organic framework, in step 1), the catalyst is 6M acetic acid, and the volume ratio of the catalyst 6M acetic acid to the mixed solvent is 1:10.

[0011] In the above method for preparing an ionic covalent organic framework, in step 2), the solvent is mesitylene and N,N-dimethylacetamide.

[0012] In the above method for preparing an ionic covalent organic framework, in step 2), the paraformaldehyde:TPBPY-COF:mesitylene:N,N-dimethylacetamide=7.2mg:20mg:0.5ml:0.5ml.

[0013] In the above method for preparing an ionic covalent organic framework, in step 2), the catalyst is trifluoroacetic acid.

[0014] In the above-mentioned method for preparing an ionic covalent organic framework, in step 2), the washing method is: after the reaction is completed, cooling to room temperature, centrifuging to obtain a solid product, centrifuging and washing three times with acetone, and vacuum drying the solid product at 60°C for 12 hours to obtain an ionic covalent organic framework im-TPBPY-COF.

[0015] The ionic covalent organic framework material prepared by the above method is used as an adsorbent in the adsorption of gold.

[0016] The above application method is as follows: weigh a certain mass of the adsorbent into 4 ml of a chloroauric acid solution of a given concentration, keep the mixture under magnetic stirring for 4 hours, filter the adsorbent, collect the supernatant, and determine the Au concentration using ICP-MS.

[0017] The beneficial effects of the present invention are:

[0018] The present invention utilizes simple post-modification to obtain the ionic covalent organic framework, which has the characteristics of simple synthesis method, stable structure, low cost and environmental friendliness.

[0019] The ionic covalent organic framework prepared by the method of the invention has good crystallinity.

[0020] The ionic covalent organic framework prepared by the method of the present invention can be used in an electrostatic adsorption mode to achieve the adsorption of AuCl4 - effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 a is the XRD spectrum of TPBPY-COF, and b is the post-modified ionized TPBPY-COF (im-TPBPY-COF), which proves that the crystallinity of the ionic covalent organic framework is maintained after post-modification.

[0022] Figure 2 It is the infrared spectra of TPBPY-COF and im-TPBPY-COF.

[0023] Figure 3 This is a comparison chart of the concentration data before and after ICP-MS measurement of im-TPBPY-COF adsorption.

[0024] Example 1

[0025] (I) Preparation of TPBPY-COF crystals:

[0026] 0.2mmol of trihydroxyphloroglucinol was mixed with 0.3mmol of 5,5'-diamino-2,2'-bipyridine, and 1ml of o-dichlorobenzene, 3ml of N,N-dimethylacetamide, and 0.4ml of 6M acetic acid were added. The mixture was degassed by freeze-thaw cycles, and then vacuum-dried, and then reacted in an oven at 120°C for 3 days. The product was separated by centrifugation, repeatedly washed with acetone, and finally dried in vacuum at 60°C for 12h to obtain TPBPY-COF crystals.

[0027] (II) Preparation of im-TPBPY-COF crystals:

[0028] Mix 20 mg of TPBPY-COF with 7.2 mg of paraformaldehyde. Then, add 0.5 ml of mesitylene, 0.5 ml of N,N-dimethylacetamide, and 0.1 ml of trifluoroacetic acid. Degas by freeze-thaw cycle, evacuate, and then react in an oven at 120°C for 12 hours. The product is separated by centrifugation, repeatedly washed with acetone, and finally dried in vacuum at 60°C for 12 hours to obtain im-TPBPY-COF crystals.

[0029] (III) Test results

[0030] Figure 1 a is the XRD spectrum of TPBPY-COF, and b is the XRD spectrum of im-TPBPY-COF, which proves that the crystallinity of the ionic covalent organic framework is maintained after post-modification.

[0031] Figure 2These are the infrared spectra of TPBPY-COF and im-TPBPY-COF. The infrared spectrum of im-TPBPY-COF produces a peak for the C=N bond, indicating that the COF skeleton is retained after ionization. At the same time, the intensity of the C=N peak is greater than that of TPBPY-COF, which is attributed to the formation of a new C=N bond in the imidazole unit, proving the successful synthesis of the post-modification.

[0032] Example 2 Im-TPBPY-COF reacts with AuCl4 in a chloroauric acid solution of a given concentration - Adsorption

[0033] The method is as follows: 2.5 mg of the adsorbent im-TPBPY-COF was weighed into 4 ml of 1000 ppm chloroauric acid solution, and the mixture was kept in dark conditions under magnetic stirring for 4 hours. The adsorbent was filtered, the supernatant was collected, and the Au concentration was determined using ICP-MS.

[0034] Figure 3 This is a comparison of the concentration data before and after ICP-MS measurement. Before adsorption, the initial chloroauric acid solution was measured by ICP-MS to obtain Au 3+ The concentration was 1000ppm. 2.5mg of TPBPY-COF and im-TPBPY-COF were weighed as adsorbents. After 4 hours of adsorption, the remaining Au in the solution 3+ The concentrations were measured by ICP-MS to be 397.5 ppm and 320.2 ppm respectively. The synthesis method of the ionic covalent organic framework of the present invention is simple, low-cost, and environmentally friendly, and realizes the AuCl4 - Highly efficient recycling, with good application prospects.

Claims

1. An ionic covalent organic framework material, characterized in that: The preparation method specifically comprises the following steps: 1) Solvothermal synthesis of covalent organic framework: trialdehyde ligand, ammonia ligand, solvent and catalyst are mixed, degassed by freeze-thaw cycle, vacuumed, and then reacted at 120°C for 3 days. The obtained reactant is centrifuged, the solid is collected, washed, and vacuum dried to obtain the covalent organic framework TPBPY-COF; 2) Post-modification synthesis of an ionic covalent organic framework: The covalent organic framework TPBPY-COF obtained in step 1), paraformaldehyde, a solvent and a catalyst are mixed, degassed by a freeze-thaw cycle, and then vacuumed, followed by reaction at 120° C. for 12 hours. The resulting reactant is centrifuged, the solid is collected, washed, and vacuum dried to obtain an ionic covalent organic framework im-TPBPY-COF.

2. The method for preparing an ionic covalent organic framework according to claim 1, characterized in that: In step 1), the trialdehyde ligand is trihydroxyphloroglucinol, the ammonia ligand is 5,5'-diamino-2,2'-bipyridine, and the solvent is o-dichlorobenzene and N,N-dimethylacetamide.

3. The method for preparing an ionic covalent organic framework according to claim 2, characterized in that: In step 1), the trialdehyde ligand: ammonia ligand: o-dichlorobenzene: N,N-dimethylacetamide = 0.2 mmol: 0.3 mmol: 1 ml: 3 ml.

4. The method for preparing an ionic covalent organic framework according to claim 1, characterized in that: In step 1), the catalyst is 6M acetic acid, and the volume ratio of the catalyst 6M acetic acid to the mixed solvent is 1:

10.

5. The method for preparing an ionic covalent organic framework according to claim 1, characterized in that: In step 2), the solvent is mesitylene and N,N-dimethylacetamide.

6. The method for preparing an ionic covalent organic framework according to claim 1, characterized in that: In step 2), the paraformaldehyde:TPBPY-COF:mesitylene:N,N-dimethylacetamide=7.2mg:20mg:0.5ml:0.5ml.

7. The method for preparing an ionic covalent organic framework according to claim 1, characterized in that: In step 2), the catalyst is trifluoroacetic acid.

8. The method for preparing an ionic covalent organic framework according to claim 1, characterized in that: In step 2), the washing method is as follows: after the reaction is completed, the mixture is cooled to room temperature, centrifuged to obtain a solid product, and centrifuged and washed three times with acetone to obtain a solid product, and then vacuum dried at 60° C. for 12 hours to obtain an ionic covalent organic framework im-TPBPY-COF.

9. Use of the ionic covalent organic framework material prepared according to the method of claim 1 as an adsorbent in the adsorption of gold.

10. The use according to claim 9, characterized in that: The adsorbent was placed in a chloroauric acid solution, the mixture was kept under magnetic stirring for 4 h, the adsorbent was filtered, the supernatant was collected, and the Au concentration was determined using ICP-MS.

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