Preparation and application method of photocatalytic material for selective rhenium separation

Abstract

The invention discloses a preparation and application method of a photocatalytic material for selective rhenium separation, which comprises the following steps: dropwise adding titanium trichloride into an ethylene glycol solution under vigorous stirring, and then continuously stirring for 30-60 minutes to obtain an intermediate solution; transferring the intermediate solution into a high-pressure reaction kettle containing a polytetrafluoroethylene lining to complete a hydrothermal reaction, naturally cooling to room temperature, and filtering to obtain a solid product; and alternately washing the solid product with ethanol and water for 2-3 times, and then carrying out forced air drying to obtain the photocatalytic material for selective rhenium separation, which is a layered bronze-phase titanium dioxide material. The photocatalytic material for selective rhenium separation prepared by the method disclosed by the invention can realize separation of Re (VII) in a scattered system within about 30-60 minutes by utilizing simulated sunlight and adjusting the pH value of a solution. Meanwhile, the catalyst has excellent carrier migration rate, relatively low carrier recombination rate and excellent chemical stability, and a hole sacrifice agent does not need to be added in the photocatalytic reaction process.

Description

Technical Field

[0001] The present invention relates to the fields of photocatalysis and enrichment of key strategic metal elements, and specifically relates to a preparation and application method of a photocatalytic material for selective rhenium separation. Background Art

[0002] Rhenium (Re) is one of the most refractory elements in nature (with a melting point as high as 3180 °C), and has physical and chemical conditions such as corrosion resistance and good plasticity, which are irreplaceable in some application fields. It can be made into superalloys with sufficient mechanical strength at high temperatures, and has now been widely used in new energy, electronic information, aerospace and other fields. However, rhenium is an extremely rare metal element on the earth, with a very low abundance in the earth's crust. It does not form or rarely forms independent minerals during the evolution of the earth, but exists in other minerals (such as molybdenum, copper, and uranium ores) in the form of isomorphism, belonging to typical scattered elements.

[0003] To extract rhenium from molybdenum concentrate roasting dust, the separation methods mainly include chemical precipitation method, ion exchange method, solvent extraction method, etc. Chemical precipitation method: In the molybdenum-rhenium acid leaching solution, calcium molybdate and potassium perrhenate precipitation methods are commonly used. Utilizing the solubility differences of calcium salts and potassium salts of molybdic acid and perrhenic acid at room temperature (the solubility of calcium molybdate is less than that of calcium perrhenate, and the solubility of potassium perrhenate is small), calcium salts and potassium salts are added to the leaching solution step by step to achieve molybdenum-rhenium separation. This method is suitable for treating high-concentration molybdenum-rhenium leaching solutions, but has poor selective separation effect for low-concentration leaching solutions, and requires repeated evaporation and concentration, with a long process flow and low efficiency. Ion exchange method: It is a method for separating molybdenum and rhenium based on the selective action differences of resins on molybdenum and rhenium ions. However, the ion exchange method has a long process flow, expensive ion exchange resins, is prone to poisoning, and is sensitive to pH and temperature. Solvent extraction method: It is a method for separation using the different distribution characteristics of ions in two immiscible phases (organic solvent and water). The extraction agents commonly used for rhenium extraction include amine, ketone, phosphine, and quaternary ammonium salt extraction agents. Although the solvent extraction method has the advantages of simple operation, strong selectivity, good separation effect, and continuous operation, the extraction agents are expensive, there is a large loss of solvent during the extraction process, and a third phase is easily formed.

[0004] Compared with traditional separation methods, photocatalysis is a green method with important application prospects in the fields of energy and environment, and has the advantages of being able to be carried out at normal temperature and pressure, simple operation, low energy consumption, green and sustainable, etc. (CN 117839666 B). However, the photo-generated electron reduction ability of existing photocatalytic materials is poor, and it strongly depends on the mediating effect of photo-generated hole sacrificial agents (such as formate), which does not meet the green and sustainable separation strategy. Therefore, it is certain that by optimizing the energy band structure of the photocatalytic material, regulating its valence band potential or surface reaction active sites, green and sustainable photocatalytic reduction separation of Re(VII) can be achieved, promoting the upgrading of the metallurgical industry and ensuring the security of the key metal supply chain. Summary of the Invention

[0005] Photocatalysis is a green method with important application prospects in the fields of energy and environment, and has the advantages of being able to be carried out at normal temperature and pressure, simple operation, low energy consumption, green and sustainable, etc. At present, the research on the reduction, separation or removal of metal ions by heterogeneous photocatalysis based on semiconductors has been successively reported. For example: Cu 2+ 、Hg 2+ 、Ag + 、Cr(VI) and U(VI), which are considered to be one of the revolutionary breakthroughs in the field of environmental remediation and pollutant purification in the 21st century. Aiming at the existing photocatalytic separation of rhenium requires the mediation of a hole sacrificial agent to achieve the green sustainability of the rhenium separation method, the present invention proposes a preparation and application method of a photocatalytic material for selective rhenium separation. The prepared photocatalytic material has excellent energy band structure and surface active sites, and has the advantages of not requiring the mediation of a hole sacrificial agent, etc. Under simulated sunlight, the selective separation of Re(VII) can be rapidly achieved under certain conditions.

[0006] The present invention first discloses a preparation method of a photocatalytic material for selective rhenium separation, including the following steps:

[0007] (1) Take ethylene glycol and water, mix and stir for 5 min to obtain an ethylene glycol solution;

[0008] (2) Under vigorous stirring, dropwise add titanium trichloride to the ethylene glycol solution, and then continue to stir for 30 - 60 min to obtain an intermediate solution;

[0009] (3) Transfer the intermediate solution to a high-pressure reaction kettle with a polytetrafluoroethylene lining to complete the hydrothermal reaction, wait for it to cool naturally to room temperature, filter to obtain a solid product;

[0010] (4) Wash the solid product alternately with ethanol and water 2 - 3 times and then dry it by blowing air to obtain the photocatalytic material for selective rhenium separation, and this photocatalytic material is a layered bronze-phase titanium dioxide material.

[0011] Further, the volume ratio of the ethylene glycol to the water in step (1) is 60:10 - 1.

[0012] Further, the dropping amount of the titanium trichloride in step (2) is 5 / 30 - 5 / 300 of the volume of the ethylene glycol; the titanium trichloride includes a 30% hydrochloric acid solution matrix by mass fraction.

[0013] Further, the hydrothermal reaction temperature in step (3) is 120 - 180 °C, and the reaction time is 8 - 12 h.

[0014] Further, the air-blowing drying temperature in step (4) is 60 °C, and the air-blowing drying time is 24 h.

[0015] The titanium dioxide powder material obtained through the above steps has a crystal phase mainly of the bronze phase (as Figure 1 shown), a band gap of approximately ~3.4 eV, and an optical absorption threshold of ~365 nm (as Figure 2 shown), presenting a layered morphological structure, with an average particle size of approximately 300 - 500 nanometers (as Figure 3 and 4 shown).

[0016] The present invention also discloses a photocatalytic material for selective rhenium separation prepared by the preparation method according to any one of the above.

[0017] The present invention also discloses an application of the above photocatalytic material for selective rhenium separation in photocatalytically selectively separating Re(VII) in a rare earth system.

[0018] Furthermore, this application includes:

[0019] Placing the photocatalytic material for selective rhenium separation in an aqueous solution of a rare earth system containing Re(VII), adjusting the solution pH < 0, and irradiating with simulated sunlight for 30 - 60 min to extract Re(VII) (as Figure 5 shown), then filtering to recover the mixture of the photocatalytic material and the rhenium product, and finally oxidizing with a certain amount of hydrogen peroxide to extract rhenium and regenerating the photocatalytic material for repeated use.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The present invention provides a simple, easy, and efficient method for selectively separating Re(VII). Benefiting from the excellent photocatalytic performance of bronze-phase titanium dioxide, it has an excellent carrier migration rate, a low carrier recombination rate, and no need to add sacrificial agents during the photocatalytic reaction process.

[0022] 2. The preparation method of the present invention has the advantages of simple material acquisition source, high photocatalytic efficiency, excellent chemical stability, etc., and has a green and sustainable development prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the X-ray diffraction pattern of the product of the present invention.

[0024] Figure 2 It is the ultraviolet-visible spectrum diagram of the product of the present invention.

[0025] Figure 3 It is the scanning electron microscope image of the product of the present invention.

[0026] Figure 4 It is the transmission electron microscope image of the product of the present invention.

[0027] Figure 5 Performance of the present invention in selectively separating Re(VII) from simulated uranium mine wastewater. Detailed implementation manners

[0028] The following implementation cases are intended to further illustrate the present invention, but should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention still fall within the protection scope of the present invention.

[0029] Example 1:

[0030] (1) Measure ethylene glycol and water in a volume ratio of 60:4 respectively, mix them and stir for 5 min to obtain an ethanol solution;

[0031] (2) Under vigorous stirring, dropwise add a titanium trichloride solution (matrix of 30% hydrochloric acid solution by mass) with a volume of 1 / 30 of the volume of ethylene glycol to the ethanol solution, and then continue to stir for 30 min to obtain an intermediate solution;

[0032] (3) Transfer the intermediate solution to a high-pressure reaction kettle with a polytetrafluoroethylene lining, carry out hydrothermal reaction at 150 °C for 10 h, filter to obtain a solid product after the reaction, and wash it alternately with ethanol and water 2 - 3 times;

[0033] (4) Dry it in a blast dryer at 60 °C for 24 h to obtain a photocatalytic material for selective rhenium separation.

[0034] Example 2:

[0035] (1) Measure ethylene glycol and water in a volume ratio of 60:2 respectively, mix them and stir for 5 min to obtain an ethanol solution;

[0036] (2) Under vigorous stirring, dropwise add a titanium trichloride solution (matrix of 30% hydrochloric acid solution by mass) with a volume of 1 / 100 of the volume of ethylene glycol to the ethanol solution, and then continue to stir for 30 min to obtain an intermediate solution;

[0037] (3) Transfer the intermediate solution to a high-pressure reaction kettle with a polytetrafluoroethylene lining, carry out hydrothermal reaction at 160 °C for 10 h, filter to obtain a solid product after the reaction, and wash it alternately with ethanol and water 2 - 3 times;

[0038] (4) Dry it in a blast dryer at 60 °C for 24 h to obtain a photocatalytic material for selective rhenium separation.

[0039] Example 3:

[0040] (1) Measure ethylene glycol and water in a volume ratio of 60:6 respectively, mix them and stir for 5 min to obtain an ethanol solution;

[0041] (2) Under vigorous stirring, dropwise add titanium trichloride solution (matrix of 30% hydrochloric acid solution by mass) with a volume of 1 / 200 of the volume of ethylene glycol to the ethanol solution, and then continue stirring for 30 min to obtain an intermediate solution;

[0042] (3) Transfer the intermediate solution to a high-pressure reactor with a polytetrafluoroethylene liner, carry out hydrothermal reaction at 170 °C for 10 h, filter to obtain a solid product after the reaction, and wash it alternately with ethanol and water 2 - 3 times;

[0043] (4) Dry it in a blast dryer at 60 °C for 24 h to obtain the photocatalytic material for selective rhenium separation.

[0044] Application Example 1:

[0045] Photocatalytic separation of rhenium from uranium ore mining waste liquid by bronze-phase TiO2

[0046] Experimental procedure for photocatalytic reduction and separation of Re(VII):

[0047] 1. Place the photocatalytic material in an aqueous solution containing Re(VII), first adjust the solution pH to 0, irradiate with simulated sunlight for 30 minutes to separate Re(VII), and then filter to recover the photocatalytic material and rhenium.

[0048] 2. Take an equal amount of the photocatalyst again and place it in the filtrate of Step 1, adjust the solution pH to 4, irradiate with simulated sunlight for 30 minutes to completely separate U(VI) in the solution, and then filter to recover the photocatalytic material and uranium synchronously. Use inductively coupled plasma optical emission spectrometry (ICP-OES) to detect the remaining amounts A of soluble rhenium and uranium, A = C t / C0×100%, where C t and C0 represent the concentrations of rhenium and uranium at a certain moment and the initial moment, respectively. The results are as Figure 5 shown. The efficiencies of photocatalytic reduction and separation of Re(VII) and U(VI) reach over 99.5% respectively, the reaction is rapid, and the effect is excellent.

[0049] The purity of the substances involved in the present invention is chemical pure or analytical pure if not specifically indicated.

[0050] The technical content not specifically described in the present invention and the above embodiments is the same as the prior art. The present invention is not limited to the above embodiments, and all the contents described in the present invention can be implemented and have the above good effects.

Claims

1. A preparation method of a photocatalytic material for selective rhenium separation, comprising: (1) Take ethylene glycol and water, mix them and stir for 5 min to obtain an ethylene glycol solution; (2) Under vigorous stirring, gradually add titanium trichloride dropwise to the ethylene glycol solution, and then continue to stir for 30 - 60 min to obtain an intermediate solution; (3) Transfer the intermediate solution to a high-pressure reaction kettle with a polytetrafluoroethylene liner to complete the hydrothermal reaction, wait for it to cool naturally to room temperature, and filter to obtain a solid product; (4) Wash the solid product 2 - 3 times alternately with ethanol and water, and then dry it by blowing air to obtain the photocatalytic material for selective rhenium separation, which is a layered bronze-phase titanium dioxide material.

2. According to the preparation method described in claim 1, wherein: The volume ratio of ethylene glycol to water in step (1) is 60:10 - 1.

3. According to the preparation method described in claim 1, wherein: The dropping amount of titanium trichloride in step (2) is 5 / 30 - 5 / 300 of the volume of ethylene glycol; The titanium trichloride includes a 30% hydrochloric acid solution matrix by mass fraction.

4. According to the preparation method described in claim 1, wherein: The hydrothermal reaction temperature in step (3) is 120 - 180 °C, and the reaction time is 8 - 12 h.

5. According to the preparation method described in claim 1, wherein: The air-blowing drying temperature in step (4) is 60 °C, and the air-blowing drying time is 24 h.

6. A photocatalytic material for selective rhenium separation prepared by the preparation method according to any one of claims 1 - 5.

7. An application of the photocatalytic material for selective rhenium separation according to claim 6 in separating Re(VII).

8. According to the application described in claim 7, including: Adding the photocatalytic material for selective rhenium separation to a dilute dispersion system with pH < 0 to selectively separate Re(VII), the illumination time is 30 - 60 min, and no hole sacrificial agent needs to be added again.

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