Preparation and application of an amidoxime functionalized UiO-66-NH2 adsorbent

Abstract

The invention discloses a preparation method for an amidoxime-functionalized UiO-66-NH2 adsorbent, belonging to the technical field of adsorbent preparation. The method comprises the following steps: S1: preparing a mixed solution one; S2: preparing a crude product one; S3: preparing UiO-66-NH2; S4: preparing a mixed solution two; S5: preparing a crude product two; S6: preparing UiO-66-CN; S7: preparing a mixed solution three; S8: preparing a crude product three; S9: preparing UiO-66-AO, i.e., an amidoxime-functionalized UiO-66-NH2 adsorbent. The invention also discloses an application of the amidoxime-functionalized UiO-66-NH2 adsorbent. The invention can adsorb gallium ions under both acidic and alkaline conditions, has higher stability under alkaline conditions, has a good adsorption effect on gallium ions, and solves the problems of the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorbent preparation, and in particular relates to the preparation and application of an amidoxime functionalized UiO-66-NH2 adsorbent. Background Art

[0002] Gallium is a "high-tech element" of high-tech industries and is widely used in electronic communications, new energy, chips, low-melting-point alloys, and military industries.

[0003] Gallium has an abundance of only 17 mg / L in the earth's crust. It is a typical rare metal and most of it exists in the form of associated minerals, making the extraction of gallium ions more difficult.

[0004] Currently, the methods for extracting gallium generally include ion exchange, solvent extraction, chlorination separation, electrodeposition separation and adsorption. Among them, ion exchange, solvent extraction, chlorination separation and electrodeposition separation generally have problems such as the generation of harmful gases, high costs and unstable separation process during the extraction process. Therefore, adsorption extraction is more widely used.

[0005] Metal-organic frameworks (MOFs) are widely used in adsorption methods due to their high specific surface area, adjustable pore structure, and abundant active sites.

[0006] UiO-66-NH2 is a type of metal-organic framework material, but the current UiO-66-NH2 has a single active site and the amino group can only exist stably under alkaline conditions, resulting in UiO-66-NH2 only being able to adsorb gallium ions under alkaline conditions, and the adsorption effect is average.

[0007] In view of this, the preparation and application of an amidoxime functionalized UiO-66-NH2 adsorbent were designed, and an amidoxime functionalized UiO-66-NH2 adsorbent was prepared to solve the problem that the existing UiO-66-NH2 can only adsorb gallium ions under alkaline conditions and the adsorption effect is general. Summary of the Invention

[0008] In order to solve the problems raised in the above background technology, the present invention provides a preparation method and application of amidoxime functionalized UiO-66-NH2 adsorbent, which has the characteristics of solving the problem that the existing UiO-66-NH2 can only adsorb gallium ions under alkaline conditions and has a general adsorption effect.

[0009] Another object of the present invention is to provide an application of an amidoxime functionalized UiO-66-NH2 adsorbent.

[0010] To achieve the above object, the present invention provides the following technical solution: Preparation of an amidoxime functionalized UiO-66-NH2 adsorbent, comprising the following steps:

[0011] S1: 2-aminoterephthalic acid and zirconium tetrachloride are placed in a dimethylformamide solution, hydrochloric acid is added dropwise, and ultrasonic stirring is performed to completely dissolve them to obtain a mixed solution 1;

[0012] S2: placing the mixed solution 1 in a reaction kettle, placing the reaction kettle in an oven, drying and crystallizing to obtain a crude product 1;

[0013] S3: Cool the crude product to room temperature, place it in a centrifuge, centrifuge, remove the solution on the crude product, wash the crude product three times with dimethylformamide solution, place it in an oven, and vacuum dry it to obtain UiO-66-NH2;

[0014] S4: placing the above UiO-66-NH2 and p-cyanobenzaldehyde in ethanol and stirring to completely dissolve them to obtain a mixed solution II;

[0015] S5: placing the mixed solution II in a pressure-resistant bottle, placing the pressure-resistant bottle in a heater, heating the heater, and causing the steam to rise, pass through a condenser, cool, and reflux back to the pressure-resistant bottle to obtain a crude product II;

[0016] S6: The crude product was cooled to room temperature, washed three times with ethanol, placed in an oven, and vacuum dried to obtain UiO-66-CN;

[0017] S7: placing the above-mentioned UiO-66-CN, hydroxylamine hydrochloride and triethylamine in ethanol and stirring to completely dissolve them to obtain a mixed solution three;

[0018] S8: placing the mixed solution 3 in a pressure-resistant bottle, placing the pressure-resistant bottle in a heater, heating the heater, causing the steam to rise, pass through a condenser, cool, and reflux back to the pressure-resistant bottle, thereby obtaining a crude product 3;

[0019] S9: The crude product was cooled to room temperature, washed three times with ethanol, placed in an oven, and vacuum dried to obtain UiO-66-AO, i.e., amidoxime functionalized UiO-66-NH2 adsorbent.

[0020] Furthermore, in step S1, the amount of 2-aminoterephthalic acid added is 1.34 g, the amount of zirconium tetrachloride added is 1.25 g, the volume of dimethylformamide solution is 60 mL, the amount of hydrochloric acid added is 10 mL, and the ultrasonic stirring time is 0.5 h.

[0021] Furthermore, in step S2, the drying and crystallization temperature of the oven is 120° C., and the drying and crystallization time is 24 hours.

[0022] Furthermore, in step S4, the amount of UiO-66-NH2 added is 1 g, the amount of p-cyanobenzaldehyde added is 0.5 g, and the volume of ethanol is 100 mL.

[0023] Furthermore, in step S5, the heating temperature of the heater is 80° C. and the reflux time is 6 hours.

[0024] Furthermore, in step S7, the amount of UiO-66-CN added is 0.8 g, the amount of hydroxylamine hydrochloride added is 10 g, the amount of triethylamine added is 14.6 g, and the volume of ethanol is 100 mL.

[0025] Furthermore, in step S8, the heating temperature of the heater is 75° C., and the reflux time is 24 hours.

[0026] Furthermore, in steps S3, S6 and S9, the vacuum drying temperature of the oven is 60°C, and the vacuum drying time is 12 hours.

[0027] The prepared amidoxime functionalized UiO-66-NH2 adsorbent is used for adsorbing gallium ions.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention uses a Schiff base reaction to react the amino group on UiO-66-NH2 with the aldehyde group in p-cyanobenzaldehyde, so that the cyano group is grafted onto the metal-organic framework material. Then, through modification, the cyano group is converted into an amidoxime group with richer active sites. The amidoxime group has more active sites and can adsorb gallium ions under both acidic and alkaline conditions. At the same time, it has higher stability under alkaline conditions and has a good adsorption effect on gallium ions, thus solving the problems of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart for preparing the adsorbent of the present invention;

[0031] Figure 2 is a characterization diagram of the adsorbent of the present invention;

[0032] Figure 3 This is a single factor experimental diagram of the adsorption of gallium ions by the adsorbent of the present invention;

[0033] Figure 4 This is a diagram of the cyclic desorption experiment of the adsorbent of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] As attached Figure 1 As shown, a preparation method of amidoxime functionalized UiO-66-NH2 adsorbent is as follows: first, UiO-66-NH2 is synthesized; then, a cyano group is grafted onto UiO-66-NH2 using p-cyanobenzaldehyde; and finally, the cyano group is converted into an amidoxime group using hydroxylamine hydrochloride or the like. Specifically, the steps include:

[0036] S1: 2-aminoterephthalic acid and zirconium tetrachloride are placed in a dimethylformamide solution, hydrochloric acid is added dropwise, and ultrasonic stirring is performed to completely dissolve them to obtain a mixed solution 1;

[0037] S2: placing the mixed solution 1 in a reaction kettle, placing the reaction kettle in an oven, drying and crystallizing to obtain a crude product 1;

[0038] S3: Cool the crude product to room temperature, place it in a centrifuge, centrifuge, remove the solution on the crude product, wash the crude product three times with dimethylformamide solution, place it in an oven, and vacuum dry it to obtain UiO-66-NH2;

[0039] S4: placing the above UiO-66-NH2 and p-cyanobenzaldehyde in ethanol and stirring to completely dissolve them to obtain a mixed solution II;

[0040] S5: placing the mixed solution II in a pressure-resistant bottle, placing the pressure-resistant bottle in a heater, heating the heater, and causing the steam to rise, pass through a condenser, cool, and reflux back to the pressure-resistant bottle to obtain a crude product II;

[0041] S6: The crude product was cooled to room temperature, washed three times with ethanol, placed in an oven, and vacuum dried to obtain UiO-66-CN;

[0042] S7: placing the above-mentioned UiO-66-CN, hydroxylamine hydrochloride and triethylamine in ethanol and stirring to completely dissolve them to obtain a mixed solution three;

[0043] S8: placing the mixed solution 3 in a pressure-resistant bottle, placing the pressure-resistant bottle in a heater, heating the heater, causing the steam to rise, pass through a condenser, cool, and reflux back to the pressure-resistant bottle, thereby obtaining a crude product 3;

[0044] S9: The crude product was cooled to room temperature, washed three times with ethanol, placed in an oven, and vacuum dried to obtain UiO-66-AO, i.e., amidoxime functionalized UiO-66-NH2 adsorbent.

[0045] Specifically, in step S1, the amount of 2-aminoterephthalic acid added is 1.34 g, the amount of zirconium tetrachloride added is 1.25 g, the volume of dimethylformamide solution is 60 mL, the amount of hydrochloric acid added is 10 mL, and the ultrasonic stirring time is 0.5 h.

[0046] Specifically, in step S2, the drying and crystallization temperature of the oven is 120° C., and the drying and crystallization time is 24 hours.

[0047] Specifically, in step S4, the amount of UiO-66-NH2 added is 1 g, the amount of p-cyanobenzaldehyde added is 0.5 g, and the volume of ethanol is 100 mL.

[0048] Specifically, in step S5, the heating temperature of the heater is 80° C., and the reflux time is 6 hours.

[0049] Specifically, in step S7, the amount of UiO-66-CN added is 0.8 g, the amount of hydroxylamine hydrochloride added is 10 g, the amount of triethylamine added is 14.6 g, and the volume of ethanol is 100 mL.

[0050] Specifically, in step S8, the heating temperature of the heater is 75° C., and the reflux time is 24 hours.

[0051] Specifically, in steps S3, S6 and S9, the vacuum drying temperature of the oven is 60°C, and the vacuum drying time is 12 hours.

[0052] A prepared amidoxime functionalized UiO-66-NH2 adsorbent was used for the adsorption of gallium ions.

[0053] As attached Figure 2 As shown in the figure, the prepared amidoxime functionalized UiO-66-NH2 adsorbent was characterized by IR, XRD, N2 adsorption-desorption curve and SEM, and the results showed that the adsorbent was successfully prepared.

[0054] As attached Figure 3 As shown, in the adsorption test, the prepared amidoxime functionalized UiO-66-NH2 adsorbent was subjected to a single factor test: 50 mL of a 100 mg / g gallium solution was prepared, and a single factor test of pH, adsorbent dosage and time was performed on it;

[0055] The results showed that the modified UiO-66-AO adsorbent can adsorb gallium ions in both acidic and alkaline conditions;

[0056] The adsorption rate before modification is only about 76%, while the adsorption rate after modification can reach about 97%;

[0057] The adsorption capacity before modification is only about 80 mg / g, while the adsorption capacity after modification can reach about 122 mg / g. Moreover, with the change of initial gallium concentration and temperature, the adsorption capacity continues to increase and can reach about 280 mg / g.

[0058] As attached Figure 4 As shown, in the adsorption test, the prepared amidoxime functionalized UiO-66-NH2 adsorbent was subjected to cyclic adsorption;

[0059] The results show that the adsorption rate of the modified UiO-66-AO adsorbent is still as high as over 95% after 5 cycles, that is, the prepared UiO-66-AO adsorbent has good cycle performance.

[0060] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. Preparation of an amidoxime functionalized UiO-66-NH2 adsorbent, characterized in that: The following steps are involved: S1: 2-aminoterephthalic acid and zirconium tetrachloride are placed in a dimethylformamide solution, hydrochloric acid is added dropwise, and ultrasonic stirring is performed to completely dissolve them to obtain a mixed solution 1; S2: placing the mixed solution 1 in a reaction kettle, placing the reaction kettle in an oven, drying and crystallizing to obtain a crude product 1; S3: Cool the crude product to room temperature, place it in a centrifuge, centrifuge, remove the solution on the crude product, wash the crude product three times with dimethylformamide solution, place it in an oven, and vacuum dry it to obtain UiO-66-NH2; S4: placing the above-mentioned UiO-66-NH2 and p-cyanobenzaldehyde in ethanol and stirring to completely dissolve them to obtain a mixed solution II; S5: placing the mixed solution II in a pressure-resistant bottle, placing the pressure-resistant bottle in a heater, heating the heater, and causing the steam to rise, pass through a condenser, cool, and reflux back to the pressure-resistant bottle to obtain a crude product II; S6: The crude product was cooled to room temperature, washed three times with ethanol, placed in an oven, and vacuum dried to obtain UiO-66-CN; S7: placing the above-mentioned UiO-66-CN, hydroxylamine hydrochloride and triethylamine in ethanol and stirring to completely dissolve them to obtain a mixed solution three; S8: placing the mixed solution 3 in a pressure-resistant bottle, placing the pressure-resistant bottle in a heater, heating the heater, causing the steam to rise, pass through a condenser, cool, and reflux back to the pressure-resistant bottle, thereby obtaining a crude product 3; S9: The crude product was cooled to room temperature, washed three times with ethanol, placed in an oven, and vacuum dried to obtain UiO-66-AO, i.e., amidoxime functionalized UiO-66-NH2 adsorbent.

2. The preparation of an amidoxime functionalized UiO-66-NH2 adsorbent according to claim 1, characterized in that: In step S1, the amount of 2-aminoterephthalic acid added is 1.34 g, the amount of zirconium tetrachloride added is 1.25 g, the volume of dimethylformamide solution is 60 mL, the amount of hydrochloric acid added is 10 mL, and the ultrasonic stirring time is 0.5 h.

3. The preparation of an amidoxime functionalized UiO-66-NH2 adsorbent according to claim 1, characterized in that: In step S2, the drying and crystallization temperature of the oven is 120° C., and the drying and crystallization time is 24 hours.

4. The preparation of an amidoxime functionalized UiO-66-NH2 adsorbent according to claim 1, characterized in that: In step S4, the amount of UiO-66-NH2 added is 1 g, the amount of p-cyanobenzaldehyde added is 0.5 g, and the volume of ethanol is 100 mL.

5. The preparation of an amidoxime functionalized UiO-66-NH2 adsorbent according to claim 1, characterized in that: In step S5, the heating temperature of the heater is 80° C. and the reflux time is 6 hours.

6. The preparation of an amidoxime functionalized UiO-66-NH2 adsorbent according to claim 1, characterized in that: In step S7, the amount of UiO-66-CN added is 0.8 g, the amount of hydroxylamine hydrochloride added is 10 g, the amount of triethylamine added is 14.6 g, and the volume of ethanol is 100 mL.

7. The preparation of an amidoxime functionalized UiO-66-NH2 adsorbent according to claim 1, characterized in that: In step S8, the heating temperature of the heater is 75° C. and the reflux time is 24 hours.

8. The preparation of an amidoxime functionalized UiO-66-NH2 adsorbent according to claim 1, characterized in that: In steps S3, S6 and S9, the vacuum drying temperature of the oven is 60°C, and the vacuum drying time is 12 hours.

9. Use of an amidoxime functionalized UiO-66-NH2 adsorbent prepared according to claims 1-8 in adsorbing gallium ions.

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