Gallium ion selective adsorbent and preparation method thereof

Abstract

The invention relates to a gallium ion selective adsorbent and a preparation method thereof. The invention creatively synthesizes the hydroxyl functionalized zirconium-based organic metal framework material with a novel structure. According to the gallium ion selective adsorbent provided by the invention, the electrical property of the surface of the adsorbent is changed from positive to negative through introduction of more hydroxyl groups, so that the adsorbent obtains electrostatic attraction to gallium ions, and the adsorption capacity and selectivity of the gallium ions are remarkably improved through imprinting modification; the problem that a traditional adsorption material is low in gallium ion selective adsorption performance is practically solved. The preparation method disclosed by the invention is simple and convenient, relatively low in cost and convenient to realize industrial production, realizes simple synthesis and recycling of the adsorption material, further reduces the production cost, does not generate harmful byproducts in the synthesis process, is environment-friendly and conforms to the green development concept.

Description

Technical Field

[0001] The invention relates to the technical field of adsorption separation, and in particular to a gallium ion selective adsorbent and a preparation method thereof. Background Art

[0002] Since gallium is present in a relatively low content in the earth's crust and mostly exists in the form of associated minerals, its extraction process is relatively complex. At present, gallium is mainly extracted from gallium-containing minerals (such as bauxite, zinc ore, etc.) or gallium-containing waste liquid. The extraction process involves multiple steps such as leaching, separation, and purification, and requires the use of advanced chemical treatment and physical separation technologies to ensure efficient and environmentally friendly extraction of high-purity gallium.

[0003] In the prior art, the separation of gallium ions mainly relies on solvent extraction, ion exchange and adsorption. However, these methods have the following problems: (1) The organic solvents used in the solvent extraction method are harmful to the environment and the operation is complicated; (2) The selectivity of the ion exchange method is poor, and it is difficult to efficiently separate gallium ions from complex solutions; (3) The adsorption capacity of traditional adsorbent materials (such as activated carbon, silica gel, etc.) for gallium ions is limited. Summary of the invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide an adsorbent for selectively adsorbing gallium and a preparation method thereof, so as to solve the problems of poor selectivity, high cost, inability to recycle the adsorbent, complex synthesis steps, and unsuitability for acidic conditions of existing adsorbents used for adsorption and separation of gallium.

[0005] The present invention provides a method for preparing a gallium ion selective adsorbent for selectively adsorbing gallium from an aqueous solution, comprising the following steps:

[0006] S1. Add MOF-808-GA to a flask containing a water-methanol mixed solution of different volume ratios, then add gallium chloride solution, and stir at room temperature for a certain period of time;

[0007] S2, slowly adding glutaraldehyde and potassium persulfate into the above mixture, and continuously stirring the reaction;

[0008] S3. After the reaction is completed, the suspension is filtered and dried. Finally, the gallium template ions in the dried product are repeatedly eluted with a hydrochloric acid solution until no Ga is detected in the filtrate. 3+ ;

[0009] S4, the product after acid washing is further washed with deionized water until neutral, and vacuum dried under certain temperature conditions to obtain the target ion-imprinted metal-organic framework material MGI;

[0010] The preparation steps of MOF-808-GA are as follows:

[0011] (1) 1,3,5-Trimethylolpropane (H 3 BTC) zirconium oxychloride octahydrate (ZrOCl 2 8H 2 O) uniformly dispersed in a mixed solution of water and glacial acetic acid, and reacted under reflux at a certain temperature;

[0012] (2) After the reaction is completed, the generated white product is collected and washed several times with a large amount of ethanol and water to remove the residual raw materials;

[0013] (3) drying the product to obtain finished product MOF-808;

[0014] (4) Dispersing the MOF-808 powder sample in the gluconic acid solution and stirring it thoroughly at a certain temperature;

[0015] (5) After stirring, the mixture was filtered, and the solid product was solvent exchanged with water and acetone in sequence, and then dried in a vacuum oven overnight to obtain MOF-808-GA.

[0016] Furthermore, in the step (1), 1,3,5-trimethylbenzene carboxylic acid (H 3 BTC) and zirconium oxychloride octahydrate (ZrOCl 2 8H 2 O) the molar mass ratio is 3:1-5:1, the stirring reflux temperature is 85°C-100°C, and the reflux time can be 7h-10h.

[0017] Furthermore, in step (3), the drying temperature is 80°C-100°C, and the drying time is 24h-36h.

[0018] Furthermore, in step (4), the concentration of the gluconic acid solution is 400 mmol / L-800 mmol / L per gram of MOF-808; the stirring temperature is 70° C.-90° C., and the stirring time is 12 h-36 h.

[0019] Furthermore, in step S1, the ratio of water to methanol is 9:1-5:5, the concentration of the gallium chloride solution is 300 mg / L-500 mg / L, and the stirring time is 15 min-60 min.

[0020] Furthermore, in the step S2, the reaction temperature is 60°C-80°C, the amount of glutaraldehyde is 2mL-3mL, the mass ratio of potassium persulfate:MOF-808-GA is 1:1-1:3, and the reaction time is 4h-8h.

[0021] Furthermore, in step S3, the concentration of elution hydrochloric acid is 0.5 mol / L-1.5 mol / L.

[0022] Furthermore, in step S4, the drying temperature is 60°C-80°C.

[0023] The present invention also provides a gallium ion selective adsorbent, which is an ion-imprinted zirconium-based metal organic framework material for selectively separating gallium obtained according to the above method.

[0024] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0025] 1. The present invention creatively synthesizes a novel hydroxyl-functionalized zirconium-based organic metal framework material.

[0026] 2. The gallium ion selective adsorbent provided by the present invention introduces more hydroxyl groups, so that the surface electrical properties of the adsorbent change from positive to negative, so that the adsorbent obtains electrostatic attraction to gallium ions.

[0027] 3. The adsorption capacity and selectivity of gallium ions are significantly improved through imprinting, which effectively solves the problem of low selective adsorption performance of traditional adsorption materials for gallium ions.

[0028] 4. The preparation method is simple, the cost is low, and it is easy to realize industrial production.

[0029] 5. The simple synthesis and recycling of adsorption materials are realized, which further reduces the production cost. No harmful by-products are produced during the synthesis process, which is environmentally friendly and in line with the concept of green development.

[0030] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0032] Figure 1 The following is a flow chart of the preparation of the adsorbent synthesized by the present invention;

[0033] Figure 2 is an X-ray diffraction analysis diagram of the adsorbent of the present invention;

[0034] Figure 3 A scanning electron microscope image of the adsorbent of the present invention is an adsorbent of the present invention;

[0035] Figure 4The infrared spectrum of the adsorbent of the present invention is a gallium adsorption performance diagram;

[0036] Figure 5 The adsorption-desorption curve and pore size curve of nitrogen of the adsorbent of the present invention at 77K;

[0037] Figure 6 The Zeta potential diagram of the adsorbent of the present invention at different pH values;

[0038] Figure 7 This is a diagram showing the selective adsorption results of the adsorbent of the present invention;

[0039] Figure 8 Schematic diagram of the adsorbent of the present invention capturing gallium ions.

[0040] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0042] In order to make the contents of the present invention easier to understand, the adsorbent of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited in any way.

[0043] The present invention provides a method for preparing a gallium ion selective adsorbent for selectively adsorbing gallium from an aqueous solution, comprising the following steps. The synthesis flow chart is shown in Figure 1 :

[0044] S1. Add hydroxylated MOF-808 (hereinafter referred to as MOF-808-GA) into a flask containing a water-methanol mixed solution in different volume ratios, then add gallium chloride solution, and stir at room temperature for a certain period of time;

[0045] S2, slowly adding glutaraldehyde and potassium persulfate into the above mixture, and continuously stirring the reaction;

[0046] S3. After the reaction is completed, the suspension is filtered and dried. Finally, the gallium template ions in the dried product are repeatedly eluted with a hydrochloric acid solution until no Ga is detected in the filtrate. 3+ ;

[0047] S4. The acid-washed product is then further washed with deionized water until neutral, and vacuum dried under certain temperature conditions to obtain the target ion-imprinted metal-organic framework material MGI.

[0048] The preparation steps of MOF-808-GA are as follows:

[0049] Step (1) 1,3,5-trimethylbenzene carboxylic acid (H 3 BTC) zirconium oxychloride octahydrate (ZrOCl 2 8H 2 O) uniformly dispersed in a mixed solution of water and glacial acetic acid, and reacted under reflux at a certain temperature;

[0050] After the reaction in step (2) is completed, the generated white product is collected and washed several times with a large amount of ethanol and water to remove the residual raw materials;

[0051] Step (3) drying the product to obtain finished product MOF-808;

[0052] Step (4) dispersing the MOF-808 powder sample in the gluconic acid solution and stirring it fully at a certain temperature;

[0053] After the stirring in step (5) is completed, the mixture is filtered, and the solid product is subjected to solvent exchange with water and acetone in sequence, and then dried overnight in a vacuum oven to obtain MOF-808-GA;

[0054] In the step (1), 1,3,5-trimethylbenzene carboxylic acid (H 3 BTC) and zirconium oxychloride octahydrate (ZrOCl 2 8H 2 O) the molar mass ratio may be 3:1-5:1, preferably 3:1;

[0055] In the step (1), the stirring reflux temperature may be 85°C-100°C, preferably 95°C;

[0056] In the step (1), the reflux time may be 7h-10h;

[0057] In the step (3), the drying temperature may be 80°C-100°C, and the drying time may be 24h-36h;

[0058] In the step (4), the concentration of the gluconic acid solution may be 400 mmol / L-800 mmol / L per gram of MOF-808, preferably 600 mmol / L;

[0059] In the step (4), the stirring temperature may be 70°C-90°C, preferably 75°C;

[0060] In the step (4), the stirring time may be 12 h to 36 h, preferably 24 h;

[0061] In step S1, the ratio of water to methanol may be 9:1-5:5, preferably 8:2;

[0062] In step S1, the concentration of the gallium chloride solution may be 300 mg / L-500 mg / L;

[0063] In step S1, the stirring time may be 15 min-60 min, preferably 30 min;

[0064] In the step S2, the reaction temperature may be 60°C-80°C;

[0065] In step S2, the amount of glutaraldehyde used may be 2 mL-3 mL, preferably 2.75 mL;

[0066] In step S2, the mass ratio of potassium persulfate to MOF-808-GA may be 1:1-1:3, preferably 1:1;

[0067] In step S2, the reaction time may be 4h-8h, preferably 5h;

[0068] In step S3, the concentration of elution hydrochloric acid may be 0.5 mol / L-1.5 mol / L;

[0069] In step S4, the drying temperature may be 60°C-80°C;

[0070] The present invention also provides a gallium ion selective adsorbent, which is an ion-imprinted zirconium-based metal organic framework material for selectively separating gallium obtained according to the above method.

[0071] Example 1

[0072] Synthesis method of hydroxyl functionalized MOF-808:

[0073] 1. In a 250 mL round-bottom flask, add 2.8 g of 1,3,5-trimethylbenzene 3 BTC) and 12.88 g of zirconium oxychloride octahydrate (ZrOCl 2 8H 2 O) was uniformly dispersed in a mixed solution of 100 mL of water and 100 mL of glacial acetic acid (AA). Subsequently, the mixed solution was refluxed at 90° C. for 8 hours.

[0074] 2. After the reaction is completed, the generated white product is collected and washed several times with a large amount of ethanol and water to remove the residual raw materials.

[0075] 3. After that, the product was dried at 100°C for 24 hours to obtain the finished product.

[0076] 4. Disperse 0.4665 g of MOF-808 powder sample in 300 mmol / L gluconic acid solution and stir thoroughly at 75 °C for 24 h.

[0077] 5. After stirring, the mixture was filtered, and the solid product was solvent exchanged with water (3 times × 50 mL) and acetone (3 times × 50 mL) in sequence, and then dried in a vacuum oven at 90° C. overnight.

[0078] Example 2

[0079] Synthesis method of ion-imprinted MOF-808-GA:

[0080] 1. Add 1g MOF-808-GA to a 250mL flask containing 100mL of a water-methanol 8:2 mixed solution in different volume ratios, then add 1mL of a 300mg / L gallium chloride solution, and stir at room temperature for 30min.

[0081] 2. Slowly add different doses of 2.75 mL of glutaraldehyde and 0.2 g of potassium persulfate into the above mixture at 70°C and continue stirring for 5 hours.

[0082] 3. After the reaction is completed, the suspension is filtered and dried. Finally, the gallium template ions in the dried product are repeatedly eluted with 1 mol / L hydrochloric acid solution until no Ga is detected in the filtrate. 3+ ,

[0083] 4. The acid-washed product was then further washed with deionized water until neutral, and vacuum dried at 60°C for 24 h to obtain the target ion-imprinted metal-organic framework material MGI.

[0084] Example 3

[0085] Characterization test of MGI:

[0086] 1. XRD patterns of MGI, hydroxylated MOF-808 and pristine MOF-808 Figure 2 As shown, the three have the same peak shape, and the positions and intensities of their diffraction peaks are highly consistent, indicating that the modification has not caused obvious damage to the structure of the crystal.

[0087] 2. SEM images of MGI Figure 3 As shown in Figure 2, many uniform pores and some irregular pores appeared on the surface of the MGI adsorbent. The appearance of uniform pores is due to the removal of template ions, while the generation of irregular pores is due to the H 2 O binds to Ga in the form of bound water3+ Participate in the synthesis process together, during the drying process H 2 The evaporation of O makes the imprinted pore size larger. On the other hand, some components of the polymer are not completely polymerized and cross-linked, and they are in contact with Ga during the acid washing process. 3+ In addition, the surface of MGI is less smooth than that of MGN, which is because Ga 3+ After reacting with MOF-808-GA, it occupied certain hydroxyl binding sites, making the sites where glutaraldehyde could act no longer uniform. Overall, SEM showed that the surface of MGI had a rich porous structure, and the imprinted layer covered the substrate relatively evenly.

[0088] 3. IR spectra of MGI, hydroxylated MOF-808 and pristine MOF-808 Figure 4 As shown, the infrared spectrum of MGI is at 1161 cm -1 and 1670cm -1 New absorption peaks related to the C=O and CO stretching vibrations of glutaraldehyde appeared at 100 nm, indicating that glutaraldehyde was successfully loaded onto the surface of the raw material. In comparison, the spectra of MGI and MOF-808-GA showed the same main peaks at similar positions, indicating that the imprinting process had little effect on the main structure of the imprinted material. 3+ After printing, 1080cm -1 The -OH peak at 1285 cm -1 A new peak appears at , which indicates that during the synthesis of the imprinting layer, the hydroxyl group of gluconic acid and the aldehyde group of glutaraldehyde undergo an aldol condensation reaction on the MGI surface.

[0089] 4. Nitrogen adsorption-desorption curves and pore size curves of MGI, hydroxylated MOF-808 and pristine MOF-808 at 77K Figure 5 As shown in Figure 2, according to the adsorption isotherm classification, the adsorption curve of MGI is consistent with the type I isotherm, showing microporous characteristics. 2 The adsorption amount further decreased, and the pore size distribution peaks were observed at 0.6 nm and 0.7 nm, which also indicated that there were mainly micropores in the sample. The specific surface area of ​​MGI was calculated by the BET method to be 479.12 m 2 / g.

[0090] 5. Zeta potential of MGI, hydroxylated MOF-808 and pristine MOF-808 at different pH values Figure 6 As shown in the figure, its value is related to the pH value of the solution. The negative value of Zeta potential indicates the presence of vacant hydroxyl groups. At the same time, the surface of MGI remains negatively charged in all solution environments, which also reveals that MGI and Ga 3+The interactions between them will also include electrostatic effects.

[0091] Example 4

[0092] A method for selectively separating gallium from a mixed ion solution, such as Figure 8 As shown, the specific steps include:

[0093] 1. Take a 100mL volumetric flask and prepare Al(NO 3 ) 3 9H 2 O、Zn(NO 3 ) 2 6H 2 O.Ga(NO 3 ) 3 9H 2 O concentration ranges from 30 mg / L to 90 mg / L of mixed solution;

[0094] 2. Use an electronic balance to accurately weigh 100 mg of the adsorbent and place it in a beaker. Next, use hydrochloric acid and sodium hydroxide to adjust the pH value of the solution. After adjusting the pH value, rinse the measuring cylinder twice with the gallium solution, then use the measuring cylinder to accurately measure 50 mL of the mixed solution and pour it into another new beaker;

[0095] 3. Place the conical flask containing the mixed solution of adsorbent and adsorbate on a constant temperature stirring table, start timing, set the adsorption time to 8h, and maintain the adsorption temperature at 25℃.

[0096] The results are as follows Figure 7 As shown in the figure, when the total concentration of Al / Ga / Zn system is gradually increased from 30 mg / L to 90 mg / L, Ga 3+ The adsorption rate of Al 3+ Although the adsorption rate on MGI has an upward trend, the increase is always controlled within 12%.

[0097] The following beneficial effects can be achieved through the present invention: 1. The present invention creatively synthesizes a novel hydroxyl-functionalized zirconium-based organic metal framework material. 2. The gallium ion selective adsorbent provided by the present invention changes the surface electrical properties of the adsorbent from positive to negative by introducing more hydroxyl groups, so that the adsorbent obtains electrostatic attraction to gallium ions. 3. The adsorption capacity and selectivity of gallium ions are significantly improved, and the problem of low selective adsorption performance of gallium ions by traditional adsorbent materials is effectively solved. 4. The preparation method is simple and the cost is low, which is convenient for industrial production. 5. The simple synthesis and recycling of adsorbent materials are realized, which further reduces the production cost, and no harmful by-products are produced during the synthesis process, which is environmentally friendly and in line with the concept of green development.

[0098] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The above-mentioned embodiments only express the implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A method for preparing a gallium ion selective adsorbent, wherein the adsorbent is used for selectively adsorbing gallium in an aqueous solution, characterized in that: The following steps are involved: S1. Add MOF-808-GA to a flask containing a water-methanol mixed solution in different volume ratios, then add gallium chloride solution, and stir at room temperature for a certain period of time; S2, slowly adding glutaraldehyde and potassium persulfate into the above mixture, and continuously stirring the reaction; S3. After the reaction is completed, the suspension is filtered and dried. Finally, the gallium template ions in the dried product are repeatedly eluted with a hydrochloric acid solution until no Ga is detected in the filtrate. 3+ ; S4, the product after acid washing is further washed with deionized water until neutral, and vacuum dried under certain temperature conditions to obtain the target ion-imprinted metal-organic framework material MGI; The preparation steps of MOF-808-GA are as follows: (1) octahydrate zirconium oxychloride (ZrOCl2·8H2O) of 1,3,5-trimethylbenzene trimesic acid (H3BTC) is uniformly dispersed in a mixed solution of water and glacial acetic acid, and the mixture is reacted and refluxed at a certain temperature; (2) After the reaction is completed, the generated white product is collected and washed several times with a large amount of ethanol and water to remove the residual raw materials; (3) drying the product to obtain finished product MOF-808; (4) Dispersing the MOF-808 powder sample in the gluconic acid solution and stirring it thoroughly at a certain temperature; (5) After stirring, the mixture was filtered, and the solid product was solvent exchanged with water and acetone in sequence, and then dried in a vacuum oven overnight to obtain MOF-808-GA.

2. The method according to claim 1, characterized in that: In the step (1), the molar mass ratio of 1,3,5-tricarboxylic acid (H3BTC) to zirconium oxychloride octahydrate (ZrOCl2·8H2O) is 3:1-5:1, the stirring reflux temperature is 85°C-100°C, and the reflux time can be 7h-10h.

3. The method according to claim 2, characterized in that: In the step (3), the drying temperature is 80°C-100°C, and the drying time is 24h-36h.

4. The method according to claim 1, characterized in that: In the step (4), the concentration of the gluconic acid solution is 400 mmol / L-800 mmol / L per gram of MOF-808; the stirring temperature is 70° C.-90° C., and the stirring time is 12 h-36 h.

5. The method according to claim 1, characterized in that: In the step S1, the ratio of water to methanol is 9:1-5:5, the concentration of the gallium chloride solution is 300 mg / L-500 mg / L, and the stirring time is 15 min-60 min.

6. The method according to claim 1, characterized in that: In the step S2, the reaction temperature is 60°C-80°C, the amount of glutaraldehyde is 2mL-3mL, the mass ratio of potassium persulfate:MOF-808-GA is 1:1-1:3, and the reaction time is 4h-8h.

7. The method according to claim 1, characterized in that: In step S3, the concentration of eluting hydrochloric acid is 0.5 mol / L-1.5 mol / L.

8. The method according to claim 1, characterized in that: In step S4, the drying temperature is 60°C-80°C.

9. A gallium ion selective adsorbent, characterized in that: The adsorbent is an ion-imprinted zirconium-based metal organic framework material for selective separation of gallium obtained according to the method of any one of claims 1 to 8.

Images