An ionic covalent organic framework material, a synthesis method thereof and application thereof in gold adsorption

Abstract

The application discloses an ion covalent organic framework material, a synthesis method thereof and application of the ion covalent organic framework material in gold adsorption, and belongs to the technical field of environmental protection; the ion covalent organic framework material is prepared by taking trihydroxyphloroglucinol as a three-link building block, reacting the three-link building block with a two-link building block of 5,5'-diamino-2,2'-bipyridine, and obtaining an imine covalent organic framework TPBPY-COF; the covalent organic framework is post-modified to obtain an ion covalent organic framework im-TPBPY-COF; and the adsorption capacity experiment on gold shows that the ion covalent organic framework has high adsorption capacity on AuCl4 ‑ , and has a removal effect; the synthesis method of the ion covalent organic framework is simple, low in cost, and friendly to the environment, high-efficiency recovery of AuCl4 ‑ in water bodies is realized, and the ion covalent organic framework has good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental protection, and particularly relates to an ion-covalent organic framework material, a synthesis method thereof and application thereof in the field of gold adsorption. BACKGROUND

[0002] With the rapid development of electronic industry and jewelry industry, the demand for gold is increasing. However, the reserves of gold ore are limited, resources are increasingly exhausted, and the mining cost is high. Therefore, it is of great economic and environmental significance to recover gold from gold-containing waste liquid. At the same time, a large amount of waste electronic products are discharged into the environment every year, and these electronic products contain a large amount of metals. Recovering gold from waste electronic products is one of the feasible strategies to solve the environmental pollution problem and alleviate the contradiction between supply and demand of gold. In the process of treating waste electronic products, gold is dissolved by strong acid to 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. Ion-covalent organic framework refers to a covalent organic framework with an ion group, has the characteristics of pre-designability, high specific surface area, adjustable pore size, stable structure and the like, and can break through the bottleneck of low adsorption efficiency by using electrostatic adsorption. At present, the application research of ion-covalent organic framework in the field of gold adsorption is still relatively few. SUMMARY

[0003] The purpose of the present application is to synthesize ion-covalent organic framework by post-modification, which has good application prospect in the field of gold adsorption.

[0004] The technical scheme of the present application is as follows: an ion-covalent organic framework material, the preparation method specifically comprises the following steps:

[0005] 1) Solvothermal synthesis of covalent organic framework: mixing triformaldehyde ligand, ammonia ligand, solvent and catalyst, vacuumizing by the method of freeze-thaw cycle degassing, then reacting at 120 DEG C for 3 days, centrifuging the obtained reaction product, collecting the solid, washing, vacuum drying, and obtaining covalent organic framework TPBPY-COF;

[0006] 2) Post-modification synthesis of ion-covalent organic framework: mixing the covalent organic framework TPBPY-COF obtained in step 1), paraformaldehyde, solvent and catalyst, vacuumizing by the method of freeze-thaw cycle degassing, then reacting at 120 DEG C for 12 hours, centrifuging the obtained reaction product, collecting the solid, washing, vacuum drying, and obtaining ion-covalent organic framework im-TPBPY-COF.

[0007] 12 hours, centrifuging the obtained reaction product, collecting the solid, washing, vacuum drying, and obtaining ion-covalent organic framework im-TPBPY-COF.

[0008] The preparation method of the ion-covalent organic framework, in step 1), the tri-aldehyde ligand is trihydroxyphloroglucinol, the ammonia ligand is 5,5'-diamino-2,2'-bipyridine, and the solvent is o-dichlorobenzene and N,N-dimethylacetamide.

[0009] The preparation method of the ion-covalent organic framework, in step 1), the tri-aldehyde ligand: ammonia ligand: o-dichlorobenzene: N,N-dimethylacetamide = 0.2 mmol: 0.3 mmol: 1 ml: 3 ml.

[0010] The preparation method of the ion-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] The preparation method of the ion-covalent organic framework, in step 2), the solvent is mesitylene and N,N-dimethylacetamide.

[0012] The preparation method of the ion-covalent organic framework, in step 2), the polyformaldehyde: TPBPY-COF: mesitylene: N,N-dimethylacetamide = 7.2 mg: 20 mg: 0.5 ml: 0.5 ml.

[0013] The preparation method of the ion-covalent organic framework, in step 2), the catalyst is trifluoroacetic acid.

[0014] The preparation method of the ion-covalent organic framework, in step 2), the washing method is as follows: after the reaction is completed, cooling to room temperature, centrifugation to obtain a solid product, washing the solid product with acetone three times by centrifugation, vacuum drying the solid product at 60 DEG C for 12 hours to obtain the ion-covalent organic framework im-TPBPY-COF.

[0015] The ion-covalent organic framework material prepared by the method is used as an adsorbent to adsorb gold.

[0016] The application is as follows: a certain mass of the adsorbent is weighed in 4 ml of a given concentration of chloroauric acid solution, and the mixture is kept under magnetic stirring for 4 hours. The adsorbent is filtered, the supernatant is collected, and the Au concentration is determined using ICP-MS.

[0017] The present application has the following advantages:

[0018] The ion-covalent organic framework is obtained by simple post-modification, and has the characteristics of simple synthesis method, stable structure, low cost and environmental friendliness.

[0019] The ion-covalent organic framework prepared by the method has good crystallinity.

[0020] The ion-covalent organic framework prepared by the method can adopt an electrostatic adsorption mode, thereby achieving the effect of adsorbing AuCl4 - . BRIEF DESCRIPTION OF DRAWINGS

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

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

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

[0024] Example 1

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

[0026] Mix 0.2 mmol of trihydroxyphloroglucinol with 0.3 mmol of 5,5'-diamino-2,2'-bipyridine, add 1 ml of o-dichlorobenzene, 3 ml of N,N-dimethylacetamide, and 0.4 ml of 6M acetic acid. Through the method of freeze-thaw cycle degassing, vacuumize, and then react in a 120°C oven for 3 days. The product is separated by centrifugation, repeatedly washed with acetone, and finally dried at 60°C under vacuum for 12 h 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. Through the method of freeze-thaw cycle degassing, vacuumize, and then react in a 120°C oven for 12 hours. The product is separated by centrifugation, repeatedly washed with acetone, and finally dried at 60°C under vacuum for 12 h to obtain im-TPBPY-COF crystals.

[0029] (III) Test results

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

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

[0032] Example 2 Adsorption of im-TPBPY-COF to AuCl4 - in a given concentration of chloroauric acid solution

[0033] The method is as follows: weigh 2.5 mg of adsorbent im-TPBPY-COF in 4 ml of chloroauric acid solution with a concentration of 1000 ppm, avoid light with tin paper, keep the mixture in the dark under magnetic stirring for 4 hours. Filter the adsorbent, collect the supernatant, and use ICP-MS to determine the Au concentration.

[0034] Figure 3 are the comparison diagrams of the concentration data before and after adsorption measured by ICP-MS. Before adsorption, the initial chloroauric acid solution measured by ICP-MS has an Au 3+ concentration of 1000 ppm, and 2.5 mg of TPBPY-COF and im-TPBPY-COF are weighed as adsorbents respectively, and after 4 hours of adsorption, the remaining Au 3+ concentration in the solution measured by ICP-MS is 397.5 ppm and 320.2 ppm respectively. The synthesis method of the ion-covalent organic framework of the application is simple, low in cost, and friendly to the environment, realizes the efficient recovery of AuCl4 - in water, and has good application prospect.

Claims

1. An ionic covalent organic framework material, characterized in that, The preparation method of the ion-covalent organic framework material specifically includes the following steps: 1) Synthesis of covalent organic framework by solvothermal method: Trialdehyde resorcinol, 5,5'-diamino-2,2'-bipyridine, o-dichlorobenzene, N,N-dimethylacetamide and catalyst were mixed and degassed by freeze-thaw cycle, vacuum was applied, and then the reaction was carried out at 120°C for 3 days. The resulting reactants were centrifuged, the solids were collected, washed, and vacuum dried to obtain the covalent organic framework TPBPY-COF; 2) Post-modification synthesis of ionic covalent organic frameworks: The covalent organic framework TPBPY-COF obtained in step 1), paraformaldehyde, solvent and catalyst were mixed and degassed by freezing-thawing cycle, vacuum was drawn, and then the reaction was carried out at 120°C for 12 hours. The resulting reactants were centrifuged, the solids were collected, washed and vacuum dried to obtain the ionic covalent organic framework im-TPBPY-COF.

2. The ionovalent organic framework material according to claim 1, characterized in that, In step 1), the ratio of trialdehyde phloroglucinol: 5,5'-diamino-2,2'-bipyridine: o-dichlorobenzene: N,N-dimethylacetamide = 0.2 mmol: 0.3 mmol: 1 ml: 3 ml.

3. The ionovalent organic framework material 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.

4. The ionovalent organic framework material according to claim 1, characterized in that, In step 2), the solvent is mesitylene and N,N-dimethylacetamide.

5. The ionovalent organic framework material according to claim 1, characterized in that, In step 2), the ratio of paraformaldehyde:TPBPY-COF:trimethylbenzene:N,N-dimethylacetamide is 7.2 mg:20 mg:0.5 ml:0.5 ml.

6. The ionovalent organic framework material according to claim 1, characterized in that, In step 2), the catalyst is trifluoroacetic acid.

7. The ionovalent organic framework material according to claim 1, characterized in that, In step 2), the washing method is as follows: after the reaction is completed, cool to room temperature, centrifuge to obtain solid product, wash three times with acetone, and dry the solid product under vacuum at 60°C for 12 hours to obtain ionic covalent organic framework im-TPBPY-COF.

8. The application of the ionic covalent organic framework material of claim 1 as an adsorbent for adsorbing gold in water.

9. The application according to claim 8, characterized in that, The adsorbent was placed in a chloroauric acid solution, and the mixture was kept under magnetic stirring for 4 hours. The adsorbent was filtered, the supernatant was collected, and the Au concentration was determined by ICP-MS.

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