A magnetic titanium phosphate material and its preparation method and its application in rare earth tail water

Abstract

The present invention discloses a magnetic titanium phosphate material, a preparation method, and its application in rare earth tailwater. These materials belong to the field of resource utilization and environmental protection technology. The material comprises a magnetic core composed of magnetic Fe3O4 nanoparticles and an adsorption-functional outer layer, a TiP layer. The TiP layer is prepared by first loading a TiO2 layer onto the core and reacting the TiO2 layer with phosphate, with the structural formula being Fe3O4@TiP. Adsorption of the rare earth tailwater is performed using a static batch method: the magnetic titanium phosphate material is added to ionic rare earth mine tailwater in a stoppered volumetric flask and subjected to oscillation adsorption at room temperature. This magnetic titanium phosphate material, its preparation method, and its application in rare earth tailwater address the difficulty of combining titanium phosphate and magnetic nanoparticles. When applied to ionic rare earth tailwater, the magnetic titanium phosphate material exhibits rapid solid-liquid separation capabilities, high adsorption capacity, high acid resistance, high selectivity, and excellent desorption and regeneration properties for rare earth ions.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization and environmental protection, and in particular to a magnetic titanium phosphate material, a preparation method thereof, and application thereof in rare earth tail water. Background Art

[0002] The mining of ionic rare earths in the south can be divided into three methods according to different process technologies: pool leaching, heap leaching and in-situ leaching. In order to protect the ecological environment, in-situ leaching is currently the main method. However, when the concentration of rare earth mother liquor is less than 0.1g·L -1 When the mine is closed and the collection of mother liquor is stopped due to economic considerations, a large amount of low-concentration rare earth tail water will be produced for a long time after the mine is closed due to the influence of rainwater leaching. If this rare earth tail water cannot be effectively treated, it will lead to environmental pollution and waste of resources.

[0003] Among various treatment methods, adsorption method is most suitable for treating low-concentration rare earth tail water, but it needs to have the advantages of high adsorption capacity, strong selectivity and rapid solid-liquid separation. 3- and HPO4 2- Titanium phosphate can be developed into an inorganic adsorption material with excellent rare earth ion adsorption. However, titanium phosphate is a nanomaterial, and there are problems such as difficulty in solid-liquid separation in practical applications. Therefore, titanium phosphate and magnetic nano-ions are compounded to prepare a magnetic titanium phosphate composite material with superparamagnetism, which can achieve rapid adsorbent solid-liquid separation under a magnetic field, and facilitate the enrichment and recovery of rare earth resources in rare earth tail water. However, when the magnetic titanium phosphate material is prepared by the direct reaction between a titanium source (such as butyl titanate, titanium tetrachloride) and a phosphorus source (such as phosphoric acid, phosphate), due to the rapid reaction between tetravalent titanium ions and phosphate radicals, it is difficult to directly load them on the magnetic core to form a titanium phosphate layer with adsorption function.

[0004] To avoid the above shortcomings, the present invention first prepares magnetic Fe3O4 nanoparticles, then loads a TiO2 layer, and finally prepares a magnetic titanium phosphate material through the reaction of the TiO2 layer and phosphate, thereby solving the problem that titanium phosphate and magnetic nano-ions are difficult to compound; when the material is applied to ionic rare earth tail water, the material has the ability of rapid solid-liquid separation, and has high adsorption capacity, high acid resistance, high selectivity and excellent desorption regeneration for rare earth ions. Summary of the Invention

[0005] The object of the present invention is to provide a magnetic titanium phosphate material, a preparation method and its application in rare earth tail water, so as to solve the problem proposed in the above background art that when preparing magnetic titanium phosphate materials by direct reaction between traditional titanium sources (such as butyl titanate, titanium tetrachloride) and phosphorus sources (such as phosphoric acid, phosphates), it is difficult to directly load them on the magnetic core to form a titanium phosphate layer with adsorption function due to the rapid reaction between tetravalent titanium ions and phosphate radicals.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution, including a magnetic core and an adsorption functional outer layer, wherein the core is a magnetic Fe3O4 nanoparticle, and the adsorption functional outer layer is a TiP layer. The TiP layer is prepared by first loading a TiO2 layer on the core and then reacting the TiO2 layer with phosphate; the structural formula is Fe3O4@TiP.

[0007] Step 1: Preparation of Fe3O4: Weigh a certain amount of ferric chloride hexahydrate, acetate, sodium citrate, and ethylene glycol, mix and stir them evenly, and react them at high temperature in a polytetrafluoroethylene-lined reactor; the reactor is naturally cooled to room temperature, and the product is washed three times with deionized water with the aid of a magnet, and vacuum-dried at 60°C for 12 hours to prepare Fe3O4;

[0008] Step 2: Weigh a certain amount of Fe3O4 and add it to a mixed solvent of ethanol and acetonitrile. Ultrasonic dispersion is performed for 10 minutes. A certain amount of ammonia water is added under mechanical stirring, and then butyl titanate is added dropwise. The reaction is continued for a period of time. The product is washed three times alternately with ethanol and acetonitrile under the assistance of a magnet and vacuum dried at 60°C for 12 hours to obtain Fe3O4@TiO2.

[0009] Step 3: Preparation of Fe3O4@TiP; weigh a certain amount of Fe3O4@TiO2, add it to the phosphate solution, and ultrasonically disperse it for 10 minutes; react in a water bath for a period of time, and after natural cooling, wash the product with deionized water to neutrality with the assistance of a magnet, and vacuum dry it at 60°C for 12 hours to obtain the magnetic titanium phosphate material Fe3O4@TiP.

[0010] Preferably, the acetate is one of ammonium acetate and sodium acetate, the mass ratio of ferric chloride hexahydrate: acetate: sodium citrate: ethylene glycol is 1:1-3:0.2-0.6:20-50, the reaction temperature is 180-200°C, the reaction time is 8-12h, and the particle size of the obtained Fe3O4 is 100-300nm.

[0011] Preferably, the amount of Fe3O4 is 0.3-0.7g×L -1 The volume ratio of acetonitrile to ethanol is 1:2-5, the volume fraction of ammonia water is 0.5-1%, the volume fraction of butyl titanate is 0.5-1%, and the reaction time is 1-5h.

[0012] Preferably, the dosage of the Fe3O4@TiO2 is 5-10 g×L-1, the phosphate is one of disodium hydrogen phosphate, sodium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium dihydrogen phosphate, and the phosphate concentration is 0.2-0.8 mol×L -1 , water bath temperature is 50-70℃, and reaction time is 8-12h.

[0013] Preferably, the adsorption of rare earth tail water adopts a static batch method, in which the magnetic titanium phosphate material is added to the ionic rare earth mine tail water in a stoppered volumetric flask, and adsorbed by shaking at room temperature; the amount of magnetic titanium phosphate material used is 0.5-2g×L -1 The rare earth concentration in the ionic rare earth tail water is 10-100 mg×L -1 , the oscillation rate is 100-200 rpm; the oscillation time is 0.5-1.5h.

[0014] Preferably, after the oscillation adsorption of the rare earth tail water is completed, the magnetic titanium phosphate material is separated into solid and liquid by a magnet; the rare earth ions in the magnetic titanium phosphate material are desorbed by an acid solution; after desorption, the magnetic titanium phosphate material is regenerated by a phosphate solution; the acid solution for desorption is one of sulfuric acid, hydrochloric acid, and nitric acid, and the acid concentration is 0.1-0.5 mol×L -1 , the desorption time is 1-2h; the phosphate solution for regeneration is one of disodium hydrogen phosphate, sodium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium dihydrogen phosphate, and the phosphate concentration is 0.2-0.6mol×L -1 , the regeneration treatment temperature is 50-70℃, and the regeneration treatment time is 1-2h.

[0015] Compared with the existing technology, the beneficial effects of the present invention are that the magnetic titanium phosphate material, the preparation method and the application in rare earth tail water comprehensively utilize the superparamagnetism of Fe3O4 nanoparticles and the strong adsorption of titanium phosphate materials to rare earth ions to prepare the magnetic titanium phosphate material Fe3O4@TiP, which is used to enrich and recover valuable rare earth resources in ionic rare earth tail water, while also reducing the pollution of rare earth ions to the environment; the magnetic titanium phosphate material has a large adsorption capacity for rare earth ions in a weak acid environment, is less interfered by ammonium ions, alkali metals and alkaline earth metal ions, has a stable material structure, can be desorbed and recycled multiple times, and can quickly separate solids and liquids under an external magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the SEM image of the magnetic titanium phosphate material Fe3O4@TiP;

[0017] Figure 2 This is the hysteresis loop diagram of the magnetic titanium phosphate material Fe3O4@TiP;

[0018] Figure 3is the initial concentration of Fe3O4@TiP adsorbing rare earth La 3+ Influence diagram of

[0019] Figure 4 Effect of solution pH on the adsorption of rare earth La on Fe3O4@TiP 3+ Influence diagram of

[0020] Figure 5 The impurity ions on Fe3O4@TiP adsorbed rare earth La 3+ Influence diagram of

[0021] Figure 6 This is the desorption regeneration diagram of magnetic titanium phosphate material Fe3O4@TiP. DETAILED DESCRIPTION

[0022] The following will provide a clear and complete description of 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] See also Figures 1-6 , the present invention provides a technical solution: the present invention provides the following technical solution;

[0024] Example 1: Step 1: Weigh 2 g of ferric chloride hexahydrate, 3.6 g of sodium acetate, 0.6 g of sodium citrate and 60 mL of ethylene glycol into a beaker and stir evenly with a glass rod until completely dissolved; transfer the mixed solution to a 100 mL polytetrafluoroethylene reactor and react at 200°C for 8 hours; wait for the reactor to cool naturally to room temperature, wash the product with deionized water three times with the assistance of a magnet, and vacuum dry at 60°C for 12 hours to obtain Fe3O4 nanoparticles.

[0025] Step 2: Weigh 50 mg of the Fe3O4 nanoparticles prepared in step 1 and disperse them in a mixed solvent of 80 mL of ethanol and 30 mL of acetonitrile, and ultrasonically disperse them for 10 minutes; add 1 mL of ammonia water under mechanical stirring, and then add 1 mL of tetrabutyl titanate dropwise, and react for 3 hours; the product is washed alternately with ethanol and acetonitrile three times with the assistance of a magnet, and vacuum-dried at 60°C for 12 hours for later use to obtain Fe3O4@TiO2.

[0026] Step 3: Weigh 100 mg of Fe3O4@TiO2 particles obtained in step 2 and add 10 mL of 0.5 mol·L -1The product was ultrasonically dispersed in a Na2HPO4 solution for 10 min and reacted in a water bath at 60°C for 10 h. The product was washed with deionized water to neutrality with the assistance of a magnet and vacuum dried at 60°C for 12 h to obtain the magnetic titanium phosphate material Fe3O4@TiP.

[0027] The structural formula of Fe3O4@TiP is:

[0028]

[0029] Magnetic titanium phosphate adsorbent is a rod-shaped adsorbent composed of a magnetic core (Fe3O4 nanoparticles) and a functional shell (titanium phosphate TiP); its scanning electron microscopy is as follows Figure 1 As shown, it can be seen that the short axis diameter of the magnetic titanium phosphate adsorption material is about 1mm and the long axis diameter is about 6mm. It is composed of magnetic Fe3O4 nanoparticles wrapped by titanium phosphate and has a large number of adsorption sites on the surface. The magnetic response test of the magnetic titanium phosphate adsorbent is carried out, as shown in FIG. Figure 2 As shown, its saturation magnetization is 12.75emu·g -1 It can be seen that the magnetic titanium phosphate adsorption material has paramagnetism and strong magnetism. When no external magnetic field is applied, the material has no magnetism and is in a dispersed state in the solution. When an external magnetic field is applied after the adsorption is completed, the material quickly agglomerates under the action of magnetic attraction to achieve solid-liquid separation.

[0030] Example 2: Using a static batch method, 8 stoppered volumetric flasks were added with 10 mL of 30, 50, 100, 150, 200, 300, 400, and 500 mg·L -1 Rare earth La 3+ solution, and then add 10 mg of magnetic titanium phosphate material Fe3O4@TiP, and use 0.1 mol·L -1 The pH value was adjusted to 5 by adding HNO3 and NaOH, and the temperature was set at 150 r·min at room temperature. -1 The adsorption was carried out at a constant speed for 60 minutes. After the adsorption, the magnetic titanium phosphate material was separated into solid and liquid by a magnet. The La in the supernatant was determined by arsenazo III spectrophotometry. 3+ concentration, calculate the Fe3O4@TiP to La 3+ The adsorption amount, such as Figure 3 As shown, it can be seen that the magnetic titanium phosphate material has a strong affinity to the rare earth La 3+ The adsorption capacity is large, and the saturated adsorption capacity can reach 164 mg g -1 .

[0031] Example 3: Using the static batch method, 8 stoppered volumetric flasks were added with 10 mL of 200 mg·L -1 Rare earth La 3+solution, and then add 10 mg of magnetic titanium phosphate material Fe3O4@TiP, and use 0.1 mol·L -1 The pH value was adjusted to 2, 3, 4, 5, 6, 7 and 8 by adding HNO3 and NaOH; the temperature was set at 150 r·min at room temperature. -1 The adsorption was carried out at a constant speed for 60 minutes. After the adsorption, the magnetic titanium phosphate material was separated into solid and liquid by a magnet. The La in the supernatant was determined by arsenazo III spectrophotometry. 3+ concentration, calculate the Fe3O4@TiP to La 3+ The adsorption amount of Figure 4 As shown in the figure, it can be seen that the adsorption capacity of Fe3O4@TiP is greater than 130 mg·g in the pH range of 3-5. -1 , has good acid resistance and strong adsorption, and is suitable for weakly acidic rare earth tail water.

[0032] Example 4: Using the static batch method, take 5 stoppered volumetric flasks and add 10 mL of rare earth La 3+ The concentration is 200 mg·L -1 , La 3+ / M n+ The mixed solutions containing impurity ions are 1:0.2, 1:0.4, 1:0.6, 1:0.8 and 1:1 respectively; the impurity ion M n+ Al 3+ , Ca 2+ Mg 2+ , K + 、Na + and NH4 + ; Then add 10mg of magnetic titanium phosphate material Fe3O4@TiP; use 0.1mol·L -1 The pH value was adjusted to 5 by HNO3 and NaOH; 150 r·min at room temperature -1 The adsorption was carried out at a constant speed for 60 minutes. After the adsorption, the magnetic titanium phosphate material was separated into solid and liquid by a magnet. The La in the supernatant was determined by arsenazo III spectrophotometry. 3+ concentration, calculate the Fe3O4@TiP to La 3+ The adsorption amount of Figure 5 As shown, you can see the one-price K + and NH4 + The effect on Fe3O4@TiP is relatively low, and the average adsorption capacity can be maintained at 150 mg·g -1 About; divalent Ca 2+ and Mg 2+ The effect on Fe3O4@TiP is slightly greater, and the average adsorption capacity can still be maintained at 80 mg·g -1 About, except Al 3+Other impurity ions other than Fe3O4@TiP adsorption of La 3+ The impact is relatively small.

[0033] Example 5: Desorption and regeneration of magnetic titanium phosphate material: 10 mg of magnetic titanium phosphate material after adsorption equilibrium was weighed into a beaker, and 10 mL of 0.1 mol·L -1 The HCl desorption solution was desorbed in a constant temperature oscillator for 1.5 h, and then solid-liquid separation was performed using a magnet to determine the rare earth La 3+ Desorption amount; after desorption, use 10mL0.5mol×L -1 Fe3O4@TiP was regenerated by NaH2PO4 solution at 50℃ for 1.5h. After regeneration, the magnetic titanium phosphate material was added with 10mL200mg×L -1 La 3+ The solution was subjected to adsorption treatment, and the adsorption operation was similar to that in Example 2; the desorption / regeneration / adsorption cycle was repeated 5 times, and the desorption and adsorption amounts of rare earth ions by Fe3O4@TiP were measured in each cycle. Figure 6 As shown in the figure, during the 5 cycles, the desorption amount increased from 163 mg·g -1 Reduced to 136 mg·g -1 , the adsorption capacity is from 182 mg·g -1 Reduced to 144 mg·g -1 , only decreased by 16% and 21% respectively, with excellent desorption and regeneration performance.

[0034] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetic titanium phosphate material comprising a magnetic core and an outer layer with an adsorption function, characterized in that: The core is a magnetic Fe3O4 nanoparticle, and the outer layer with adsorption function is a TiP layer. The TiP layer is prepared by first loading a TiO2 layer on the core and then reacting the TiO2 layer with phosphate. The structural formula is Fe3O4@TiP. The preparation of the magnetic titanium phosphate material comprises the following steps: Step 1: Preparation of Fe3O4; weighing a certain amount of ferric chloride hexahydrate, acetate, sodium citrate and ethylene glycol, mixing and stirring them uniformly, and reacting them at high temperature in a reactor with a polytetrafluoroethylene liner; the reactor is naturally cooled to room temperature, the product is washed three times with deionized water with the assistance of a magnet, and vacuum dried at 60°C for 12 hours to prepare Fe3O4; Step 2: Weigh a certain amount of Fe3O4 and add it to a mixed solvent of ethanol and acetonitrile. Ultrasonic dispersion is performed for 10 minutes. A certain amount of ammonia water is added under mechanical stirring, and then butyl titanate is added dropwise. The reaction is continued for a period of time. The product is washed three times alternately with ethanol and acetonitrile under the assistance of a magnet and vacuum dried at 60°C for 12 hours to obtain Fe3O4@TiO2. Step 3: Preparation of Fe3O4@TiP: Weigh a certain amount of Fe3O4@TiO2, add it to the phosphate solution, and ultrasonically disperse it for 10 minutes; react in a water bath for a period of time, and after natural cooling, wash the product with deionized water with the assistance of a magnet until it is neutral, and vacuum dry it at 60°C for 12 hours to obtain the magnetic titanium phosphate material Fe3O4@TiP; The phosphate is one of disodium hydrogen phosphate, sodium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium dihydrogen phosphate, and the phosphate concentration is 0.2-0.8 mol×L -1 , water bath temperature is 50-70℃, and reaction time is 8-12h.

2. The method for preparing a magnetic titanium phosphate material according to claim 1, wherein: The acetate is one of ammonium acetate and sodium acetate, the mass ratio of ferric chloride hexahydrate: acetate: sodium citrate: ethylene glycol is 1:1-3:0.2-0.6:20-50, the reaction temperature is 180-200°C, the reaction time is 8-12h, and the particle size of the prepared Fe3O4 is 100-300nm.

3. The method for preparing a magnetic titanium phosphate material according to claim 1, wherein: The amount of Fe3O4 is 0.3-0.7g×L -1 The volume ratio of acetonitrile to ethanol is 1:2-5, the volume fraction of ammonia water is 0.5-1%, the volume fraction of butyl titanate is 0.5-1%, and the reaction time is 1-5h.

4. The method for preparing a magnetic titanium phosphate material according to claim 1, wherein: The amount of Fe3O4@TiO2 is 5-10g×L -1 .

5. The use of a magnetic titanium phosphate material in rare earth tail water according to claim 1, characterized in that: The adsorption of rare earth tail water adopts static batch method, in which magnetic titanium phosphate material is added to ionic rare earth mine tail water in a stoppered volumetric flask and adsorbed under oscillation at room temperature; The amount of magnetic titanium phosphate material is 0.5-2g×L -1 The rare earth concentration in the ionic rare earth tail water is 10-100 mg×L -1 , the oscillation rate is 100-200 rpm; the oscillation time is 0.5-1.5h.

6. The use of a magnetic titanium phosphate material in rare earth tail water according to claim 5, characterized in that: After the rare earth tail water is vibrated and adsorbed, the magnetic titanium phosphate material is separated into solid and liquid by a magnet; the rare earth ions in the magnetic titanium phosphate material are desorbed by an acid solution; and after desorption, the magnetic titanium phosphate material is regenerated by a phosphate solution; The acid solution for desorption is one of sulfuric acid, hydrochloric acid, and nitric acid, with an acid concentration of 0.1-0.5 mol×L -1 , the desorption time is 1-2h; the phosphate solution for regeneration is one of disodium hydrogen phosphate, sodium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium dihydrogen phosphate, and the phosphate concentration is 0.2-0.6mol×L -1 , the regeneration treatment temperature is 50-70℃, and the regeneration treatment time is 1-2h.

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