CN104388087B - Utilize the method that waste phosphor powder prepares rare-earth fluorescent up-conversion - Google Patents

Abstract

The invention relates to a method for preparing a rare earth fluorescent up-conversion material by using waste fluorescent powder, which comprises the following steps: weighing the waste fluorescent powder in the process, leaching the fluorescent powder through a sulfuric acid solution to obtain a solution; separating solid and liquid, adjusting pH with ammonia water, and performing a precipitation. Secondary precipitation, third precipitation, fourth precipitation, aging, filtration, to obtain filter residue; high temperature burning, cooling to room temperature, adding MOH solution, and then suction filtration to obtain white powder; adding hydrochloric acid solution, evaporated to dryness, obtained Mixture of yttrium chloride hydrochloride and europium chloride anhydrous, MOH solid and MHF ₂ fine powder and RmF ₃ or RmCl ₃ solid, uniform; add high boiling point solvent, heat up, stir; centrifuge, the obtained solid powder is mixed with n-hexane or acetone Centrifugal washing and drying, and then washing with boiling water for several times, drying, that is. The advantages and characteristics of the present invention are: the green high-value resource comprehensive utilization of rare earth elements in the rare earth three-primary-color fluorescent powder waste can be realized.

Description

Method for preparing rare earth fluorescent up-conversion material by using waste fluorescent powder

technical field

The invention relates to a new technology for resource utilization of solid waste, especially suitable for the green high-value resource utilization of rare earth three-primary-color fluorescent powder waste, and specifically relates to a method for synthesizing rare earth fluorescent up-conversion materials from secondary rare earth resources.

Background technique

Rare-earth fluorescent up-conversion fluorescent materials refer to materials that can absorb long-wave radiation with low photon energy and emit short-wave radiation with high photon energy based on a two-photon or multi-photon mechanism when the material is excited by light. It is essentially an anti-Stokes glow. In recent years, up-conversion luminescent materials have broad application prospects in solid-state laser, three-dimensional display, infrared imaging, solar cells, especially as a new type of fluorescent marker in biomacromolecule analysis and biomedical clinical fields, and have received extensive attention. . Compared with traditional fluorescent markers, upconversion luminescent nanomaterials have the advantages of low toxicity, high luminescence intensity, resistance to photobleaching and photodegradation, etc., which can realize ultrasensitive biological detection. At the same time, because the excitation light of upconversion luminescent nanomaterials is infrared light, it can avoid the interference of autofluorescence of biological samples and the phenomenon of scattered light, thereby reducing the detection background and improving the signal-to-noise ratio, and the damage of infrared light to biological tissues during the detection process is also reduced. smaller.

With the gradual recognition of rare earth fluorescent up-conversion materials in the market, the demand for them in related industries is increasing. At present, the most commonly used rare earth fluorescent up-conversion materials are based on yttrium fluoride as the matrix material. In view of the technical limitations of the preparation method, the crystal hydration of yttrium oxide or yttrium chloride with a purity of more than 99% is required in the preparation process. yttrium nitrate crystal hydrate to ensure the fluorescence effect, and the above-mentioned raw materials with a purity of more than 99% basically come from rare earth ores. Mining rare earth ores consumes a lot of energy and resources and brings a series of environmental problems, and my country's rare earth strategic reserves are increasing. The government began to gradually restrict the mining of rare earths, so the price of the above-mentioned raw materials became increasingly expensive, which eventually led to the high cost of the prepared rare earth fluorescent up-conversion materials, which is a fatal flaw for the industrialization and marketing of rare earth fluorescent up-conversion materials.

Rare earth is an important non-renewable strategic resource. Because of its excellent optical, electrical, magnetic and other characteristics, it has been widely used in many fields such as electronic information, metallurgical machinery, petrochemical industry, energy environment, national defense and military industry. my country is the country with the most abundant rare earth resources, but with the increase of domestic rare earth consumption demand, a large number of cheap exports and long-term predatory mining and other factors, my country's rare earth reserves have dropped sharply. In recent years, the amount of scrapped rare earth products and materials in my country has been increasing. For example, in 2014 alone, the amount of rare earth three-color phosphor waste generated in my country reached 8,000 tons, but it has not been properly recycled. Therefore, the environmentally friendly recycling of rare earth tricolor phosphor waste can protect the environment and greatly improve the utilization efficiency of rare earth resources. Waste CRT TVs, waste PDP TVs, tricolor fluorescent lamps, mobile phone and other electronic product displays contain a large amount of rare earth elements. On average, each waste CRT TV contains about 8 grams of phosphor powder, and each waste PDP TV contains about 30 grams of phosphor powder. Only three primary color fluorescent lamps contain about 3 grams of phosphor. Waste phosphors mainly contain rare earth elements yttrium and europium, in addition to rare earth elements such as cerium, terbium, and dysprosium. From the perspective of protecting rare earth resources, recycling rare earth resources, and environmental protection, it is imperative to recycle rare earth resources in phosphors.

At present, in the field of rare earth resource recovery of waste phosphor powder, fluorescent grade yttrium oxide and europium oxide mixture have been successfully extracted from phosphor powder, because there are too many impurities such as aluminum, calcium, barium, manganese, magnesium, silicon and other elements. Oxide has not been applied to rare-earth fluorescent up-conversion materials in the current field of fluorescent material preparation, but because it comes from waste phosphor powder, its yield and cost advantages are much higher than that of yttrium oxide with higher purity currently on the market.

Contents of the invention

The purpose of the present invention is to provide a method for preparing rare-earth fluorescent up-conversion materials by using waste fluorescent powder, thereby greatly reducing the raw material cost of rare-earth fluorescent up-conversion materials and reducing environmental pollution caused by waste fluorescent powder.

The technical scheme adopted by the present invention to solve the above-mentioned technical problems is: a method for preparing rare earth fluorescent up-conversion materials by using waste fluorescent powder, comprising the following steps:

1) Weighing the waste phosphor powder from the process, leaching the phosphor powder through a 1.5mol/L-2.5mol/L sulfuric acid solution, and using hydrogen peroxide as a co-solvent to obtain a solution;

2) Put the solution in step 1) into a centrifuge for solid-liquid separation, adjust the pH of the obtained leachate to 3.5-4 with ammonia water, perform a precipitation, filter, and obtain the filtrate;

3) adding ammonia water to the filtrate in step 2), performing secondary precipitation, adjusting the pH to 7-8, filtering to obtain filter residue A and retaining the filtrate;

4) Add ammonia water to the filtrate in step 3), carry out three precipitations, adjust the pH to 8-9, and filter to obtain the filter residue B;

5) Dissolving the filter residue A in step 3) and the filter residue B in step 4) with sulfuric acid solution to obtain an enriched solution, adding boiling water, stirring, slowly adding oxalic acid solution, performing four precipitations, aging, and filtering to obtain filter residue C ;

6) Burn the filter residue C in step 5) at high temperature, after cooling to room temperature, add MOH solution and keep it at 80°C for 10h, then perform suction filtration to obtain a white powder of a mixture mainly containing yttrium oxide and europium oxide; then add Hydrochloric acid solution to dissolve it completely, and after the solution is transparent and clear, heat and evaporate the solution to dryness to obtain a mixture of anhydrous yttrium chloride and anhydrous europium chloride;

7) Weigh the mixture of anhydrous yttrium chloride and anhydrous europium chloride obtained in step 6), MOH solid and MHF ₂ fine powder and RmF ₃ or RmCl ₃ solid, and mix them uniformly to obtain a solid mixture;

8) Add a high-boiling point solvent to the solid mixture obtained in step 7), and then rapidly raise the temperature under the protection of an inert gas atmosphere, keep the reaction temperature at 200°C-350°C, and react with magnetic stirring for 30min-3h;

9) The liquid obtained after the reaction in step 8) is subjected to high-speed centrifugation, and the obtained solid powder is directly washed with n-hexane or acetone and ultrasonically washed several times and dried, then washed with boiling water for several times, and dried to obtain the rare earth fluorescence upconversion Material.

The present invention first washes several times with normal hexane or acetone centrifugally, and dries, and the purpose is to remove the oleic acid ligand attached to the surface of the reaction product; Potassium, sodium chloride, europium chloride, europium fluoride and other by-products.

According to the above scheme, step 6) and step 7) in MOH, MHF M in M is Na, any one and _two kinds of K, _RmF or _RmCl Rm in Rm is Er, Tm, any one in Ho species and mixtures of species.

According to the above scheme, the mass ratio of the mixture of anhydrous yttrium chloride and anhydrous europium chloride, MOH solid, MHF fine powder, _RmF or _RmCl solid in step ₇ ) is 1: (0.1-0.5): (0.2- 2): (0.01-0.3).

According to the above scheme, step 8) medium and high boiling point solvent is one of oleic acid, oleylamine, octadecene or two or more mixed solvents; if mixed solvent is selected, the dosage ratio of each component solvent can be adjusted as needed Determine; after selecting the corresponding solvent, the reaction temperature in the corresponding step (8) is required to be lower than the minimum boiling point of the selected solvent component, such as octadecene 314°C oleylamine 340°C oleic acid 360°C;

Advantages and characteristics of the present invention:

1. Part of the raw materials used in the present invention are waste materials, which are low in cost and easy to obtain. This process is simple, the preparation conditions are mild, and there is no secondary pollution to the environment. It can realize the green high-value resources of rare earth elements in the waste materials of rare earth three primary color phosphors Comprehensive utilization;

2. The present invention uses oleic acid as a wet chemical method as a solvent, uses MHF ₂ (wherein M is any one or both of Na and K) as a fluorine source, and under the interference condition of a certain amount of europium ions, it is first used in KYF ₄ Only Er ions were doped in the matrix material, and KYF ₄ : Er ³⁺ nanocrystals with excellent luminous efficiency were successfully prepared; the sensitizing ions Yb ³⁺ and Er ³⁺ ions were also successfully mixed into the NaYF4 matrix material, and Hexagonal phase NaYF4:Yb ³⁺ , Er ³⁺ microcrystals with excellent luminous efficiency are obtained.

3. The rare earth fluorescent up-conversion material prepared by the present invention has better luminous efficiency, wide source of raw materials, low cost, and simple process flow. By appropriately changing the reaction conditions, the particle size can be effectively controlled to the nanometer level, so that the rare earth fluorescent up-conversion material prepared by this method can The conversion materials can be effectively applied in the field of biomarkers, which is of great significance to the further marketization of rare earth fluorescent up-conversion materials.

Description of drawings

Fig. 1 is the XRD diffraction peak pattern of the nanoscale KYF ₄ : Er ³⁺ rare earth fluorescent up-conversion material prepared in Example 1;

Fig. 2 is the field emission scanning electron micrograph of the nanoscale KYF ₄ : Er ³⁺ rare earth fluorescence up-conversion material prepared in Example 1;

Fig. 3 is the fluorescence spectrum of the nanoscale KYF ₄ : Er ³⁺ rare earth fluorescent upconversion luminescent material prepared in Example 1 pumped by a 980nm laser in the 400nm-800nm band;

Fig. 4 is the XRD diffraction peak pattern of the hexagonal phase NaYF ₄ : Yb ³⁺ , Er ³⁺ rare earth fluorescent up-conversion material prepared in Example 2;

Fig. 5 is a scanning electron micrograph of the hexagonal phase NaYF ₄ : Yb ³⁺ , Er ³⁺ rare earth fluorescence up-conversion material prepared in Example 2;

Fig. 6 is the fluorescence spectrum of the hexagonal NaYF ₄ : Yb ³⁺ , Er ³⁺ rare earth fluorescent upconversion material prepared in Example 2 pumped by a 980nm laser in the 400nm-800nm band.

detailed description

In order to better understand the present invention, the content of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the following examples.

Example 1

The specific steps of preparing rare earth fluorescent up-conversion materials with waste phosphor powder are as follows:

(1) Weigh a certain amount of process waste phosphor powder, leach the phosphor powder through a 2mol/L sulfuric acid solution, and add an appropriate amount of hydrogen peroxide as a cosolvent, at a temperature of 70°C, and leach for 4 hours to obtain a solution;

(2) Put the solution in step (1) into a centrifuge for solid-liquid separation, adjust the pH value of the obtained leachate to 3.5-4 with ammonia water, perform a precipitation, filter, and obtain the filtrate;

(3) Add ammonia water to the filtrate in step (2), carry out secondary precipitation, adjust the pH value to 7-8, filter to obtain filter residue A and retain the filtrate;

(4) adding ammonia water to the filtrate in step (3), carrying out three precipitations, adjusting the pH value to 8-9, filtering to obtain filter residue B;

(5) Dissolve filter residue A in step (3) and filter residue B in step (4) with sulfuric acid solution to obtain enriched solution, add boiling water, stir, and slowly add oxalic acid solution at a temperature of 80°C for four steps. Precipitate for the second time, age for 4h, filter to obtain filter residue C;

(6) Burn the filter residue C in step (5) at a high temperature of 1000°C for 2h, after cooling to room temperature, add a certain concentration of KOH solution and keep it at a temperature of 80°C for 10h, then perform suction filtration to obtain a white powder, and obtain It mainly contains a mixture of yttrium oxide and europium oxide; then add hydrochloric acid solution to dissolve it completely, heat and evaporate the solution after the solution is transparent and clear, and obtain a white mixture of anhydrous yttrium chloride and anhydrous europium chloride (wherein anhydrous chloride The mass ratio of yttrium to anhydrous europium chloride is about 13:1).

(7) Weigh 0.2g of the white mixture of anhydrous yttrium chloride and anhydrous europium chloride obtained in step (6), respectively weigh _KOH solid and KHF fine powder 0.05g, 0.2g, and then weigh fluoride Erbium 0.008g, mix the weighed four parts of solids and add them into a 100ml three-necked flask, then add 25ml oleic acid and a stirring magnetic seed to the 100ml three-necked flask, the reaction is carried out in a closed system and the stirring magnetic seed is in a stirring state from beginning to end (The stirring rate is 3000-5000rpm/min, which can be adjusted according to the situation). After vacuuming at room temperature, close the vacuum valve, and then pass argon or nitrogen into the reactor, and quickly heat up to 330 at a heating rate of 10-20°C/min. ℃, the temperature was maintained at about 330 ℃ for 70 minutes, and the heating was stopped, and the reactant was cooled to room temperature.

(8) Pour the reaction solution obtained in step (7) into a centrifuge tube and carry out centrifugation to obtain a white solid, add 10ml of acetone, ultrasonically vibrate for 5-10min, add acetone and wash centrifugally for 3 times, then wash with boiling water several times, Drying, the purpose is to remove by-products such as potassium chloride, potassium fluoride, europium chloride, europium fluoride and other by-products in the reactant, to obtain the micron-scale rare earth fluorescent up-conversion material KYF ₄ :Er ³⁺ of the present invention ; Dry at 60°C and store in vacuum.

The phase, morphology and fluorescence properties of the final product were characterized by XRD, TEM and fluorescence spectrometer. See Figure 1 for the XRD diffraction pattern, and the result analysis shows that the synthesized nanoparticles are KYF ₄ :Er ³⁺ , without impurity peaks; see Figure 2 for the transmission electron microscope photo and high-resolution image of KYF ₄ :Er ³⁺ , and Figure 2 shows the crystal grains Irregular granular shape with fuzzy grain edges, the average grain size is about 150nm; use 980nm laser to excite KYF ₄ : Er ³⁺ up-conversion rare earth nano-fluorescence material to measure fluorescence spectrum, at 500-550nm and 650-675nm There are green and red spectral peaks appearing in the area, as shown in Figure 3.

Example 2

The specific steps of preparing rare earth fluorescent up-conversion materials with waste phosphor powder are as follows:

(1) Weigh a certain amount of process waste phosphor powder, leach the phosphor powder through a 2mol/L sulfuric acid solution, and add an appropriate amount of hydrogen peroxide as a cosolvent, at a temperature of 70°C, and leach for 4 hours to obtain a solution;

(2) Put the solution in step (1) into a centrifuge for solid-liquid separation, adjust the pH value of the obtained leachate to 3.5-4 with ammonia water, perform a precipitation, filter, and obtain the filtrate;

(3) Add ammonia water to the filtrate in step (2), carry out secondary precipitation, adjust the pH value to 7-8, filter to obtain filter residue A and retain the filtrate;

(4) adding ammonia water to the filtrate in step (3), carrying out three precipitations, adjusting the pH value to 8-9, filtering to obtain filter residue B;

(5) Dissolve the filter residue A in step 3) and the filter residue B in step (4) with sulfuric acid solution to obtain the enrichment solution, add boiling water, stir, and slowly add the oxalic acid solution at a temperature of 80°C for four times Precipitate, age for 4h, filter to obtain filter residue C;

(6) Burn the filter residue C in step (5) at a high temperature of 1000°C for 2h, after cooling to room temperature, add a certain concentration of NaOH solution and keep it at a temperature of 80°C for 10h, then perform suction filtration to obtain a white powder, and obtain It mainly contains a mixture of yttrium oxide and europium oxide; then add hydrochloric acid solution to dissolve it completely, heat and evaporate the solution after the solution is transparent and clear, and obtain a white mixture of anhydrous yttrium chloride and anhydrous europium chloride (wherein anhydrous chloride The mass ratio of yttrium to anhydrous europium chloride is about 13:1).

(7) Take by weighing 0.2g of the white mixture of anhydrous yttrium chloride and anhydrous europium chloride obtained in step (6), respectively weigh sodium hydroxide solid and _NaHF fine powder 0.04g, 0.16g, and then weigh Erbium fluoride 0.01g, ytterbium fluoride (ytterbium ions are doped into the NaYF4 matrix as a sensitizer, which can enhance the fluorescence effect of the material) 0.08g, and four parts of solids weighed are mixed and added to a 100ml three-necked flask, and then Add 25ml of oleic acid and a stirring magnetic seed into a 100ml three-necked flask. The reaction is carried out in a closed system and the stirring magnetic seed is in a stirring state from the beginning to the end (the stirring rate is 3000-5000rpm/min, which can be adjusted according to the situation). After vacuuming at room temperature, close the Vacuum valve, then pass argon or nitrogen into the reactor, rapidly raise the temperature to 330°C at a rate of 10-20°C/min, maintain the temperature at about 330°C for 80 minutes, stop heating, and wait for the reactants to cool to room temperature.

(8) Pour the reaction solution obtained in step (7) into a centrifuge tube and carry out centrifugation to obtain a white solid, add 10ml of acetone, ultrasonically vibrate for 5-10min, add acetone and wash centrifugally for 3 times, then wash with boiling water several times, Drying, the purpose is to remove by-products such as sodium fluoride, sodium chloride, europium chloride, europium fluoride and other by-products in the reactants; to obtain the micron-scale rare earth fluorescent up-conversion material NaYF ₄ : Yb ³⁺ described in the present invention , Er ³⁺ .

The phase, morphology and fluorescence properties of the final product were characterized by XRD, TEM and fluorescence spectrometer. See Figure 4 for the XRD diffraction pattern, and the result analysis shows that the synthesized micron particles are NaYF ₄ : Yb ³⁺ , Er ³⁺ , without impurity peaks; NaYF ₄ : Yb ³⁺ , Er ³⁺ , see Figure 5, Figure 5 shows that the grains are regular hexagonal phase, the grain edges are clear, the grain distribution is relatively uniform, and the average grain size is about 1 μm; use 980nm laser to excite NaYF ₄ : Yb ³⁺ , Er ³⁺ upconversion rare earth microns The fluorescence spectrum of the fluorescent material is measured, and there are green and red spectral peaks in the 500-550nm and 650-675nm regions, as shown in Figure 6.

Example 3

The specific steps of preparing rare earth fluorescent up-conversion materials with waste phosphor powder are as follows:

(1) Weigh a certain amount of process waste phosphor powder, leach the phosphor powder through a 2mol/L sulfuric acid solution, and add an appropriate amount of hydrogen peroxide as a cosolvent, at a temperature of 70°C, and leach for 4 hours to obtain a solution;

(2) Put the solution in step (1) into a centrifuge for solid-liquid separation, adjust the pH value of the obtained leachate to 3.5-4 with ammonia water, perform a precipitation, filter, and obtain the filtrate;

(3) Add ammonia water to the filtrate in step (2), carry out secondary precipitation, adjust the pH value to 7-8, filter to obtain filter residue A and retain the filtrate;

(4) adding ammonia water to the filtrate in step (3), carrying out three precipitations, adjusting the pH value to 8-9, filtering to obtain filter residue B;

(5) Dissolve the filter residue A in step 3) and the filter residue B in step (4) with sulfuric acid solution to obtain the enrichment solution, add boiling water, stir, and slowly add the oxalic acid solution at a temperature of 80°C for four times Precipitate, age for 4h, filter to obtain filter residue C;

(6) Burn the filter residue C in step (5) at a high temperature of 1000°C for 2h, after cooling to room temperature, add a certain concentration of KOH solution and keep it at a temperature of 80°C for 10h, then perform suction filtration to obtain a white powder, and obtain It mainly contains a mixture of yttrium oxide and europium oxide; then add hydrochloric acid solution to dissolve it completely, heat and evaporate the solution after the solution is transparent and clear, and obtain a white mixture of anhydrous yttrium chloride and anhydrous europium chloride (wherein anhydrous chloride The mass ratio of yttrium to anhydrous europium chloride is about 13:1).

(7) Weigh 0.2g of the white mixture of anhydrous yttrium chloride and anhydrous europium chloride obtained in step (6), respectively weigh _NaOH solid and KHF fine powder 0.1g, 0.2g, and then weigh fluoride Erbium 0.008g, mix the weighed four parts of solids and add them into a 100ml three-necked flask, then add 25ml oleic acid and a stirring magnetic seed to the 100ml three-necked flask, the reaction is carried out in a closed system and the stirring magnetic seed is in a stirring state from beginning to end (The stirring rate is 3000-5000rpm/min, which can be adjusted according to the situation). After vacuuming at room temperature, close the vacuum valve, and then pass argon or nitrogen into the reactor, and quickly heat up to 330 at a heating rate of 10-20°C/min. ℃, the temperature was maintained at about 330 ℃ for 70 minutes, and the heating was stopped, and the reactant was cooled to room temperature.

(8) Pour the reaction solution obtained in step (7) into a centrifuge tube and carry out centrifugation to obtain a white solid, add 10ml of acetone, ultrasonically vibrate for 5-10min, add acetone and wash centrifugally for 3 times, then wash with boiling water several times, Drying, the purpose is to remove by-products such as potassium chloride, potassium fluoride, sodium fluoride, sodium chloride, europium chloride, europium fluoride and other by-products in the reactant; Conversion material K ₂ NaYF ₆ : Er ³⁺ .

Example 4

The specific steps of preparing rare earth fluorescent up-conversion materials with waste phosphor powder are as follows:

(1) Weigh a certain amount of process waste phosphor powder, leach the phosphor powder through a 2mol/L sulfuric acid solution, and add an appropriate amount of hydrogen peroxide as a cosolvent, at a temperature of 70°C, and leach for 4 hours to obtain a solution;

(2) Put the solution in step (1) into a centrifuge for solid-liquid separation, adjust the pH value of the obtained leachate to 3.5-4 with ammonia water, perform a precipitation, filter, and obtain the filtrate;

(3) Add ammonia water to the filtrate in step (2), carry out secondary precipitation, adjust the pH value to 7-8, filter to obtain filter residue A and retain the filtrate;

(4) adding ammonia water to the filtrate in step (3), carrying out three precipitations, adjusting the pH value to 8-9, filtering to obtain filter residue B;

(5) Dissolve the filter residue A in step 3) and the filter residue B in step (4) with sulfuric acid solution to obtain the enrichment solution, add boiling water, stir, and slowly add the oxalic acid solution at a temperature of 80°C for four times Precipitate, age for 4h, filter to obtain filter residue C;

(6) Burn the filter residue C in step (5) at a high temperature of 1000°C for 2h, after cooling to room temperature, add a certain concentration of NaOH solution and keep it at a temperature of 80°C for 10h, then perform suction filtration to obtain a white powder, and obtain It mainly contains a mixture of yttrium oxide and europium oxide; then add hydrochloric acid solution to dissolve it completely, heat and evaporate the solution after the solution is transparent and clear, and obtain a white mixture of anhydrous yttrium chloride and anhydrous europium chloride (wherein anhydrous chloride The mass ratio of yttrium to anhydrous europium chloride is about 13:1).

(7) Weigh 0.2g of the white mixture of anhydrous yttrium chloride and anhydrous europium chloride obtained in step (6), respectively weigh NaOH solid and _NaHF fine powder 0.04g, 0.16g, and then weigh fluoride Thulium 0.01g, ytterbium fluoride (ytterbium ions are doped into the NaYF4 matrix as a sensitizer, which can enhance the fluorescence effect of the material) 0.08g, the four parts of solids weighed are mixed and added to a 100ml three-necked flask, and then added to a 100ml Add 25ml of oleic acid, 5ml of oleylamine and a stirring magnetic seed into the three-necked flask. The reaction is carried out in a closed system and the stirring magnetic seed is in a stirring state from the beginning to the end (the stirring rate is 3000-5000rpm/min, which can be adjusted according to the situation). , close the vacuum valve, then pass argon or nitrogen into the reactor, rapidly raise the temperature to 320°C at a heating rate of 10-20°C/min, maintain the temperature at about 320°C for 80 minutes, stop heating, and wait for the reactants to cool to room temperature .

(8) Pour the reaction solution obtained in step (7) into a centrifuge tube and carry out centrifugation to obtain a white solid, add 10ml of acetone, ultrasonically vibrate for 5-10min, add acetone and wash centrifugally for 3 times, then wash with boiling water several times, Drying, the purpose is to remove by-products such as sodium fluoride, sodium chloride, europium chloride, europium fluoride and other by-products in the reactants; to obtain the rare earth fluorescent up-conversion material NaYF ₄ : Yb ³⁺ , Tm ³⁺ .

Example 5

The specific steps of preparing rare earth fluorescent up-conversion materials with waste phosphor powder are as follows:

(1) Weigh a certain amount of process waste phosphor powder, leach the phosphor powder through a 2mol/L sulfuric acid solution, and add an appropriate amount of hydrogen peroxide as a cosolvent, at a temperature of 70°C, and leach for 4 hours to obtain a solution;

(2) Put the solution in step (1) into a centrifuge for solid-liquid separation, adjust the pH value of the obtained leachate to 3.5-4 with ammonia water, perform a precipitation, filter, and obtain the filtrate;

(3) Add ammonia water to the filtrate in step (2), carry out secondary precipitation, adjust the pH value to 7-8, filter to obtain filter residue A and retain the filtrate;

(4) adding ammonia water to the filtrate in step (3), carrying out three precipitations, adjusting the pH value to 8-9, filtering to obtain filter residue B;

(5) Dissolve the filter residue A in step 3) and the filter residue B in step (4) with sulfuric acid solution to obtain the enrichment solution, add boiling water, stir, and slowly add the oxalic acid solution at a temperature of 80°C for four times Precipitate, age for 4h, filter to obtain filter residue C;

(6) Burn the filter residue C in step (5) at a high temperature of 1000°C for 2h, after cooling to room temperature, add a certain concentration of KOH solution and keep it at a temperature of 80°C for 10h, then perform suction filtration to obtain a white powder, and obtain It mainly contains a mixture of yttrium oxide and europium oxide; then add hydrochloric acid solution to dissolve it completely, heat and evaporate the solution after the solution is transparent and clear, and obtain a white mixture of anhydrous yttrium chloride and anhydrous europium chloride (wherein anhydrous chloride The mass ratio of yttrium to anhydrous europium chloride is about 13:1).

(7) Weigh 0.2g of the white mixture of anhydrous yttrium chloride and anhydrous europium chloride obtained in step (6), respectively weigh _KOH solid and KHF fine powder 0.05g, 0.2g, and then weigh fluoride Holmium 0.01g, mix the weighed four solids and add them into a 100ml three-necked flask, then add 25ml oleic acid, 5ml octadecene and a stirring magnetic seed to the 100ml three-necked flask, the reaction is carried out under a closed system and stirred from beginning to end The magnetic seed is in a stirring state (the stirring rate is 3000-5000rpm/min, which can be adjusted according to the situation). After vacuuming at room temperature, close the vacuum valve, and then pass argon or nitrogen into the reactor to increase the temperature at a rate of 10-20°C/min. The temperature was raised rapidly to 310°C, and the temperature was maintained at about 310°C for 70 minutes, then the heating was stopped, and the reactant was cooled to room temperature.

(8) Pour the reaction solution obtained in step (7) into a centrifuge tube and carry out centrifugation to obtain a white solid, add 10ml of acetone, ultrasonically vibrate for 5-10min, add acetone and wash centrifugally for 3 times, then wash with boiling water several times, The purpose of drying is to remove by-products such as potassium chloride, potassium fluoride, europium chloride, europium fluoride and other by-products in the reactants; to obtain the rare earth fluorescent upconversion material KYF ₄ :Ho ³⁺ described in the present invention.

Claims (3)

1. A method for preparing a rare earth fluorescent up-conversion material by using waste fluorescent powder, comprising the following steps: 1) Weighing the waste phosphor powder from the process, leaching the phosphor powder through a 1.5mol/L-2.5mol/L sulfuric acid solution, and using hydrogen peroxide as a co-solvent to obtain a solution; 2) Put the solution in step 1) into a centrifuge for solid-liquid separation, adjust the pH of the obtained leachate to 3.5-4 with ammonia water, perform a precipitation, filter, and obtain the filtrate; 3) adding ammonia water to the filtrate in step 2), performing secondary precipitation, adjusting the pH to 7-8, filtering to obtain filter residue A and retaining the filtrate; 4) Add ammonia water to the filtrate in step 3), carry out three precipitations, adjust the pH to 8-9, and filter to obtain the filter residue B; 5) Dissolving the filter residue A in step 3) and the filter residue B in step 4) with sulfuric acid solution to obtain an enriched solution, adding boiling water, stirring, slowly adding oxalic acid solution, performing four precipitations, aging, and filtering to obtain filter residue C ; 6) Burn the filter residue C in step 5) at high temperature, after cooling to room temperature, add MOH solution and keep it at 80°C for 10h, then perform suction filtration to obtain a white powder of a mixture mainly containing yttrium oxide and europium oxide; then add Hydrochloric acid solution to dissolve it completely, and after the solution is transparent and clear, heat and evaporate the solution to dryness to obtain a mixture of anhydrous yttrium chloride and anhydrous europium chloride; 7) Weigh the mixture of anhydrous yttrium chloride and anhydrous europium chloride, MOH solid and MHF fine powder and _RmF or _RmCl solid obtained in step ₆ ), and mix them uniformly to obtain a solid mixture; wherein, M in MOH and MHF ₂ is any one or two of Na and K, Rm in RmF ₃ or RmCl ₃ is any one or a mixture of Er, Tm, Ho; 8) Add a high-boiling point solvent to the solid mixture obtained in step 7), and then rapidly raise the temperature under the protection of an inert gas atmosphere, keep the reaction temperature at 200°C-350°C, and react with magnetic stirring for 30min-3h; 9) The liquid obtained after the reaction in step 8) is subjected to high-speed centrifugation, and the obtained solid powder is directly washed with n-hexane or acetone and ultrasonically washed several times and dried, then washed with boiling water for several times, and dried to obtain the rare earth fluorescence upconversion Material. 2. the method for utilizing waste fluorescent powder to prepare rare earth fluorescent up-conversion material according to claim 1, is characterized in that, in step 7), the mixture of anhydrous yttrium chloride and anhydrous europium _chloride , MOH solid, MHF Fine The mass ratio of powder, _RmF3 or _RmCl3 solid is 1: (0.25-0.5): (1-2): (0.01-0.1). 3. the method for utilizing waste fluorescent powder to prepare rare earth fluorescent up-conversion materials according to claim 1, is characterized in that, step 8) medium high boiling point solvent is wherein one or more of oleic acid, oleylamine, octadecene mix.