Method for preparing up-conversion luminescent material by using fluorine-chlorine-containing waste acid recycling product

Abstract

The invention discloses a method for preparing an up-conversion luminescent material by using a fluorine-chlorine-containing waste acid recycling product, which comprises the following steps of: mixing calcium carbonate and fluorine-chlorine-containing waste acid to react, and separating to obtain a fluorine-containing calcium chloride liquid phase and a chlorine-containing calcium fluoride solid phase; mixing mayenite into a fluorine-containing calcium chloride liquid phase, reacting, and separating to obtain a calcium chloride liquid phase and a calcium-aluminum fluorine removal product; and mixing the chlorine-containing calcium fluoride solid phase, the calcium-aluminum defluorination product and a rare earth oxide, and calcining to obtain the up-conversion luminescent material. The mayenite is adopted to remove fluorine from the fluorine-containing calcium chloride liquid phase, and the obtained calcium-aluminum fluorine-removed product can be prepared into the up-conversion luminescent material with the chlorine-containing calcium fluoride solid phase and the rare earth oxide, so that harmless treatment of the fluorine-chlorine-containing waste acid and resource utilization of the product are realized; meanwhile, the obtained up-conversion luminescent material is low in fluorine ion leaching rate, free of leaching toxicity and high in luminescent intensity value.

Description

Technical Field

[0001] The invention relates to a method for preparing an up-conversion luminescent material by utilizing the resource recovery product of fluorine-containing chlorine waste acid, and belongs to the technical field of resource recovery of fluorine-containing chlorine waste acid. Background Art

[0002] At present, the methods for treating fluorine-containing chlorine waste acid mainly include adsorption method, precipitation method, membrane method, electrochemical method and ion exchange method. Among them, adsorption method and precipitation method are the most widely used. Precipitation method includes chemical precipitation method, crystal precipitation method and coagulation precipitation method. Chemical precipitation method is the earliest method used to treat fluorine-containing chlorine waste acid, which is widely used because of its simple process flow, convenient operation, low investment and low cost. At present, calcium salt precipitation method is mainly used in industry to treat fluorine-containing chlorine waste acid, that is, calcium salts such as lime or calcium chloride are added to fluorine-containing chlorine waste acid, so that fluorine ions and calcium ions generate insoluble calcium fluoride (CaF2) precipitation, thereby removing fluorine ions.

[0003] Calcium fluoride is a colorless crystal or white powder, which is insoluble in water, slightly soluble in inorganic acids, and reacts with hot concentrated sulfuric acid to produce hydrofluoric acid. Calcium fluoride is widely used in metallurgy, chemical industry, building materials, optics and other industries. However, the direct utilization of low-purity calcium fluoride slag is difficult, and it is usually treated by landfill or cement making. This treatment method is not only inefficient and costly, but also prone to fluorine pollution, because calcium fluoride sludge has fluoride ion leaching toxicity. This phenomenon is particularly evident in the fluoride-containing sludge generated during the production of solar panels. If these sludges are not properly handled, the leaching of fluoride ions may cause serious harm to the environment. Therefore, there is an urgent need to develop more economical and environmentally friendly fluorine-containing chlorine waste acid and calcium fluoride sludge treatment technology.

[0004] Currently available upconversion luminescent materials are usually prepared by the synthesis of calcium fluoride and rare earth oxides (ytterbium oxide, erbium oxide, etc.). Calcium fluoride is a commonly used matrix of upconversion luminescent materials, and upconversion luminescence is achieved by doping rare earth elements (erbium, ytterbium, thulium, etc.). These materials can convert low-energy light (near-infrared light) into high-energy light (visible light) under excitation light emission, and exhibit upconversion luminescence. However, the upconversion luminescence conversion materials obtained by these traditional preparation methods often have the problem of low luminescence intensity. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing an up-conversion luminescent material by utilizing the resource-based products of fluorine-containing chlorine-containing waste acid. The method comprises the following steps: a fluorine-containing calcium chloride liquid phase and a chlorine-containing calcium fluoride solid phase are obtained by mixing and reacting calcium carbonate and fluorine-containing chlorine-containing waste acid and separating them; the fluorine-containing calcium chloride liquid phase is defluorinated by using calcium aluminum; and the obtained calcium aluminum defluorination product is further used to prepare an up-conversion luminescent material together with the chlorine-containing calcium fluoride solid phase and a rare earth oxide, thereby achieving harmless treatment of fluorine-containing chlorine-containing waste acid and resource utilization of the product, reducing the disposal cost of solid waste residue, and having extensive economic and social benefits; meanwhile, the obtained up-conversion luminescent material has a low fluorine ion leaching rate, does not have leaching toxicity, and has a high luminescence intensity value.

[0006] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0007] A method for preparing an up-conversion luminescent material using a resource product of fluorine-containing chlorine waste acid, specifically comprising:

[0008] First, calcium carbonate is mixed with fluorine-containing chlorine-containing waste acid for reaction and then separated to obtain a fluorine-containing calcium chloride liquid phase and a chlorine-containing calcium fluoride solid phase;

[0009] Then the mayenite is mixed into the fluorine-containing calcium chloride liquid phase for reaction and then separated to obtain the calcium chloride liquid phase and the calcium aluminum defluorination product;

[0010] Then, the chlorine-containing calcium fluoride solid phase and the calcium aluminum defluorination product are mixed with rare earth oxides and calcined to obtain an upconversion luminescent material. Preferably, the fluorine ion concentration in the fluorine-containing chlorine waste acid is 10000-50000 mg / L, and the chloride ion concentration is 10000-15000 mg / L;

[0011] The mass ratio of calcium carbonate to fluorine-containing chlorine-containing waste acid is (1-5):10.

[0012] Preferably, the conditions for the mixed reaction of calcium carbonate and fluorine-containing chlorine waste acid are: stirring for 2-5 hours at room temperature.

[0013] Preferably, the fluoride ion concentration in the fluoride-containing calcium chloride liquid phase is 30-80 mg / L;

[0014] The mass ratio of calcium aluminum oxide to the fluorine-containing calcium chloride liquid phase is (0.01-0.1):1.

[0015] Preferably, the preparation method of mayenite is: mixing an aluminum source and a calcium source in a molar ratio of aluminum to calcium of 1:(0.8-1.5) and drying the mixture at 70-100°C.

[0016] Preferably, the aluminum source is one or more of aluminum oxide, aluminum hydroxide, aluminum nitrate and aluminum sulfate;

[0017] The calcium source is one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium nitrate, calcium bicarbonate and calcium sulfate.

[0018] Preferably, the conditions for the liquid phase reaction of mayenite and fluorine-containing calcium chloride are: stirring for 1-3 hours at room temperature.

[0019] Preferably, the mass ratio of the chlorine-containing calcium fluoride solid phase, the calcium aluminum defluorination product and the rare earth oxide is 1:(0.1-0.3):(0.01-0.05);

[0020] The rare earth oxide is obtained by mixing ytterbium oxide and erbium oxide in a mass ratio of 1:(0.01-0.05).

[0021] Preferably, the calcination conditions are: 500-700° C., 1-5 h.

[0022] Preferably, the fluorine ion leaching rate of the obtained up-conversion luminescent material is 0.001-0.01%.

[0023] The beneficial effects of the present invention are:

[0024] Calcium aluminum has a large specific surface area and porous structure, which can effectively adsorb fluoride ions in water. At the same time, there is an electrostatic effect on the surface of calcium aluminum, and fluoride ions can be attracted and attached to its surface; and fluoride ions can react chemically with the active sites on the surface of calcium aluminum to form stable calcium fluoride products, which are fixed on the surface. Therefore, fluoride ions can be effectively captured and fixed, and fluoride ions can be removed from the fluoride-containing calcium chloride liquid phase.

[0025] The residual chloride ions in the solid phase of chloride-containing calcium fluoride can promote the doping of rare earth oxides erbium oxide and ytterbium oxide into the crystal lattice of calcium fluoride. The crystal structure of calcium fluoride belongs to the cubic system. In this structure, calcium ions (Ca 2+ ) is located at the face center of the crystal, while the fluoride ion (F-) occupies the body center of the lattice. This arrangement gives calcium fluoride crystals good stability and structural compactness, and can produce fluorescent materials with excellent luminescence properties. In addition, rare earth erbium ions and ytterbium ions can form rare earth fluoride salts with a small amount of fluoride ions that have seeped out of calcium fluoride. These rare earth fluoride salts have lower solubility, which not only gives upconversion luminescence properties, but also further improves the stability and safety of the chlorine-containing calcium fluoride solid phase.

[0026] The invention utilizes calcium carbonate and fluorine-containing chlorine-containing waste acid to react in a mixed manner to obtain a fluorine-containing calcium chloride liquid phase and a chlorine-containing calcium fluoride solid phase, and then utilizes calcium aluminum to remove fluoride ions in the fluorine-containing calcium chloride liquid phase. The process is simple and the operation is convenient, and a high-purity calcium chloride supernatant and a calcium aluminum defluoridation product can be obtained. The calcium aluminum defluoridation product can be mixed with a chlorine-containing calcium fluoride solid phase and rare earth oxides (ytterbium oxide and erbium oxide) to prepare a non-toxic up-conversion luminescent material with high luminescence performance, thereby realizing the resource utilization of fluorine-containing chlorine-containing waste acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the XRD pattern of calcium fluoride containing chloride ions obtained in step 1 of Example 5;

[0028] Figure 2 This is a SEM image of the calcium fluoride containing chloride ions obtained in step 1 of Example 5;

[0029] Figure 3 is the up-conversion emission spectrum of the up-conversion luminescent material prepared in Examples 1-5;

[0030] Figure 4 1 and 2 are the up-conversion emission spectra of the up-conversion luminescent materials prepared in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0031] In the following embodiments, the fluorine ion concentration in the fluorine-containing chlorine waste acid (the waste acid is HF and HCl) is 50000 mg / L, and the chloride ion concentration is 10000 mg / L; the calcium aluminum oxide is prepared by the following preparation method, specifically: aluminum sulfate and calcium oxide are mixed in a molar ratio of aluminum to calcium of 1:1 and then dried at 80°C.

[0032] Example 1

[0033] Calcium carbonate and fluorine-containing chlorine waste acid are mixed in a solid-liquid mass ratio of 0.3:1, stirred and reacted at room temperature for 3 hours, and then the solid and liquid are separated to obtain a calcium chloride supernatant containing fluoride ions and a calcium fluoride precipitate containing chloride ions; the fluoride ion concentration in the obtained calcium chloride supernatant containing fluoride ions is 80 mg / L, and the fluoride removal rate reaches 99.84%.

[0034] Calcium aluminum sulfate and calcium chloride supernatant containing fluoride ions are mixed at a solid-liquid mass ratio of 0.01:1, and the mixture is stirred for reaction at room temperature for 1 hour, followed by solid-liquid separation to obtain calcium chloride supernatant and calcium aluminum defluoridation product; the fluoride ion concentration in the obtained calcium chloride supernatant is 0.8 mg / L, and the fluoride removal rate reaches 99.99%.

[0035] The calcium fluoride precipitate containing chloride ions, the calcium aluminum defluorination product, and the rare earth oxide (obtained by mixing ytterbium oxide and erbium oxide in a mass ratio of 1:0.01) were mixed in a mass ratio of 1:0.1:0.01, stirred by dry method for 1.5 hours, and then calcined at 500°C to obtain an upconversion luminescent material. The fluoride ion leaching rate of the obtained upconversion luminescent material was 0.01%, and it emitted red light with a wavelength of 650nm under a 980nm laser ( Figure 3 ).

[0036] Example 2

[0037] Calcium carbonate and fluorine-containing chlorine waste acid are mixed in a solid-liquid mass ratio of 0.3:1, stirred and reacted at room temperature for 5 hours, and then the solid and liquid are separated to obtain a calcium chloride supernatant containing fluoride ions and a calcium fluoride precipitate containing chloride ions; the fluoride ion concentration in the obtained calcium chloride supernatant containing fluoride ions is 63 mg / L, and the fluoride removal rate reaches 99.87%.

[0038] Calcium aluminum sulfate and calcium chloride supernatant containing fluoride ions are mixed at a solid-liquid mass ratio of 0.03:1, and the mixture is stirred for reaction at room temperature for 1 hour, followed by solid-liquid separation to obtain calcium chloride supernatant and calcium aluminum defluoridation product; the fluoride ion concentration in the obtained calcium chloride supernatant is 0.6 mg / L, and the fluoride removal rate reaches 99.99%.

[0039] The calcium fluoride precipitate containing chloride ions, the calcium aluminum defluorination product, and the rare earth oxide (obtained by mixing ytterbium oxide and erbium oxide in a mass ratio of 1:0.03) were mixed in a mass ratio of 1:0.1:0.03, stirred by dry method for 2 hours, and then calcined at 550°C to obtain an upconversion luminescent material. The fluoride ion leaching rate of the obtained upconversion luminescent material was 0.008%, and it emitted green light with a wavelength of 520nm under a 980nm laser ( Figure 3 ).

[0040] Example 3

[0041] Calcium carbonate and fluorine-containing chlorine waste acid are mixed in a solid-liquid mass ratio of 0.4:1, and the mixture is stirred for reaction at room temperature for 4 hours, followed by solid-liquid separation to obtain a calcium chloride supernatant containing fluoride ions and a calcium fluoride precipitate containing chloride ions; the fluoride ion concentration in the obtained calcium chloride supernatant containing fluoride ions is 51 mg / L, and the fluoride removal rate reaches 99.90%.

[0042] Calcium aluminum sulfate and calcium chloride supernatant containing fluoride ions are mixed at a solid-liquid mass ratio of 0.05:1, and the mixture is stirred for reaction at room temperature for 2 hours, followed by solid-liquid separation to obtain calcium chloride supernatant and calcium aluminum defluoridation product; the fluoride ion concentration in the obtained calcium chloride supernatant is 0.4 mg / L, and the fluoride removal rate reaches 99.99%.

[0043] The calcium fluoride precipitate containing chloride ions, the calcium aluminum defluorination product, and the rare earth oxide (obtained by mixing ytterbium oxide and erbium oxide in a mass ratio of 1:0.03) were mixed in a mass ratio of 1:0.2:0.04, stirred by dry method for 2.5 hours, and then calcined at 600°C to obtain an upconversion luminescent material. The fluoride ion leaching rate of the obtained upconversion luminescent material was 0.005%, and it emitted green light with a wavelength of 520nm and ultraviolet light with a wavelength of 380nm under a 980nm laser ( Figure 3 ).

[0044] Example 4

[0045] Calcium carbonate and fluorine-containing chlorine waste acid are mixed in a solid-liquid mass ratio of 0.5:1, stirred and reacted at room temperature for 3 hours, and then the solid and liquid are separated to obtain a calcium chloride supernatant containing fluoride ions and a calcium fluoride precipitate containing chloride ions; the fluoride ion concentration in the obtained calcium chloride supernatant containing fluoride ions is 39 mg / L, and the fluoride removal rate reaches 99.92%.

[0046] Calcium aluminum sulfate and calcium chloride supernatant containing fluoride ions are mixed at a solid-liquid mass ratio of 0.1:1, and the mixture is stirred for reaction at room temperature for 2 hours, followed by solid-liquid separation to obtain calcium chloride supernatant and calcium aluminum defluoridation product; the fluoride ion concentration in the obtained calcium chloride supernatant is 0.2 mg / L, and the fluoride removal rate reaches 99.99%.

[0047] The calcium fluoride precipitate containing chloride ions, the calcium aluminum defluorination product, and the rare earth oxide (obtained by mixing ytterbium oxide and erbium oxide in a mass ratio of 1:0.05) were mixed in a mass ratio of 1:0.3:0.04, stirred by dry method for 3 hours, and then calcined at 650°C to obtain an upconversion luminescent material. The fluoride ion leaching rate of the obtained upconversion luminescent material was 0.005%, and it emitted red light with a wavelength of 650nm and green light with a wavelength of 520nm under a 980nm laser ( Figure 3 ).

[0048] Example 5

[0049] Calcium carbonate and fluorine-containing chlorine waste acid are mixed in a solid-liquid mass ratio of 0.5:1, stirred and reacted at room temperature for 5 hours, and then the solid and liquid are separated to obtain a calcium chloride supernatant containing fluoride ions and a calcium fluoride precipitate containing chloride ions; the fluoride ion concentration in the obtained calcium chloride supernatant containing fluoride ions is 30 mg / L, and the fluoride removal rate reaches 99.94%.

[0050] Calcium aluminum sulfate and calcium chloride supernatant containing fluoride ions are mixed at a solid-liquid mass ratio of 0.1:1, and the mixture is stirred for reaction at room temperature for 3 hours, followed by solid-liquid separation to obtain calcium chloride supernatant and calcium aluminum defluoridation product; the fluoride ion concentration in the obtained calcium chloride supernatant is 0.1 mg / L, and the fluoride removal rate reaches 99.99%.

[0051] The calcium fluoride precipitate containing chloride ions, the calcium aluminum defluorination product, and the rare earth oxide (obtained by mixing ytterbium oxide and erbium oxide in a mass ratio of 1:0.05) were mixed in a mass ratio of 1:0.3:0.05, stirred in a dry method for 1 hour, and then calcined at 700°C to obtain an upconversion luminescent material. The fluoride ion leaching rate of the obtained upconversion luminescent material was 0.001%, and it emitted red light with a wavelength of 650nm, green light with a wavelength of 520nm, and ultraviolet light with a wavelength of 380nm under a 980nm laser ( Figure 3 ).

[0052] Figure 1 The XRD pattern of calcium fluoride containing chloride ions obtained in step 1 of Example 5. The obtained CaF2 was tested by X-ray diffraction spectrometer (XRD), and it can be seen that there are obvious characteristic peaks of CaF2 when 2θ is 28.26°, 46.99°, 55.75°, 68.65°, and 75.83°, and the characteristic peak crystal planes are (111), (220), (311), (400), and (331), which are consistent with the standard card JCPDS19-0629 of CaF2.

[0053] Figure 2 This is a SEM image of calcium fluoride containing chloride ions obtained in step 1 of Example 5. The calcium fluoride particles begin to agglomerate, making their radial dimensions larger and showing obvious crystalline features on the surface, with more grain boundaries and granular morphologies.

[0054] Comparative Example 1

[0055] Calcium fluoride without chloride ions was directly used, and the calcium aluminum defluorination product obtained in Example 5 and rare earth oxide (ytterbium oxide and erbium oxide were mixed in a mass ratio of 1:0.05) were mixed in a mass ratio of 1:0.3:0.05, and dry stirred for 1 hour and calcined at 700° C. to obtain an up-conversion luminescent material. The leaching rate of fluoride ions in the obtained up-conversion luminescent material was 0.002%, and red light with a wavelength of 650 nm, green light with a wavelength of 520 nm, and ultraviolet light with a wavelength of 380 nm were emitted under the same 980 nm laser.

[0056] The luminescent properties of the upconversion luminescent materials obtained in Comparative Example 1 and Example 5 were further tested, and it was found that the upconversion emission spectra mainly included red light, green light and ultraviolet light, and the intensity values ​​of each light were: Example 5> Comparative Example 1 ( Figure 4). This shows that the presence of chlorine in the up-conversion luminescent material component can improve its luminescence performance. The reason is that during the calcination process, the residual chloride ions in the calcium fluoride solid phase can react with rare earth oxides to form rare earth chlorides, thereby enhancing the activity of rare earth ions, increasing the diffusion rate and doping depth of rare earth ions in calcium fluoride crystals, and helping to disperse rare earth doping elements and prevent agglomeration. In addition, the chloride ions themselves are highly corrosive, which helps to create more defects or vacancies in the calcium fluoride lattice as channels for rare earth ion doping, which is beneficial for rare earth elements to better enter the crystal structure of calcium fluoride; and the presence of chloride ions in the calcium fluoride solid phase will change the local charge balance and ion spacing of the calcium fluoride lattice, which is beneficial to the doping of rare earth ions. The combined influence of these factors enables the calcium fluoride solid phase containing chloride ions to obtain an up-conversion luminescent material with stronger luminescence intensity after calcining with calcium aluminum defluorination products and rare earth oxides.

[0057] The above is only a preferred implementation of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the patent of the present invention. These improvements and modifications should also be regarded as the scope of protection of the patent of the present invention.

Claims

1. A method for preparing up-conversion luminescent materials using the resource products of fluorine-containing chlorine waste acid, characterized in that: Specifically: First, calcium carbonate is mixed with fluorine-containing chlorine-containing waste acid for reaction and then separated to obtain a fluorine-containing calcium chloride liquid phase and a chlorine-containing calcium fluoride solid phase; Then the mayenite is mixed into the fluorine-containing calcium chloride liquid phase for reaction and then separated to obtain the calcium chloride liquid phase and the calcium aluminum defluorination product; Then, the chlorine-containing calcium fluoride solid phase and the calcium aluminum defluorination product are mixed with the rare earth oxide and calcined to obtain an up-conversion luminescent material.

2. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to claim 1, characterized in that: In fluorine-containing chlorine waste acid, the fluoride ion concentration is 10000-50000 mg / L, and the chloride ion concentration is 10000-15000 mg / L; The mass ratio of calcium carbonate to fluorine-containing chlorine-containing waste acid is (1-5):

10.

3. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to claim 1, characterized in that: The conditions for the mixed reaction of calcium carbonate and fluorine-containing chlorine waste acid are: stirring for 2-5 hours at room temperature.

4. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to claim 1, characterized in that: In the fluoride-containing calcium chloride liquid phase, the fluoride ion concentration is 30-80 mg / L; The mass ratio of calcium aluminum oxide to the fluorine-containing calcium chloride liquid phase is (0.01-0.1):

1.

5. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to any one of claims 1 or 4, characterized in that: The preparation method of mayenite is as follows: an aluminum source and a calcium source are mixed according to a molar ratio of aluminum to calcium of 1:(0.8-1.5), and then the mixture is dried at 70-100°C to obtain the mayenite.

6. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to claim 5, characterized in that: The aluminum source is one or more of aluminum oxide, aluminum hydroxide, aluminum nitrate and aluminum sulfate; The calcium source is one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium nitrate, calcium bicarbonate and calcium sulfate.

7. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to claim 1, characterized in that: The conditions for the liquid phase reaction of calcium aluminum sulfate and fluoride-containing calcium chloride are: stirring for 1-3 hours at room temperature.

8. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to claim 1, characterized in that: The mass ratio of the chlorine-containing calcium fluoride solid phase, the calcium aluminum defluorination product and the rare earth oxide is 1:(0.1-0.3):(0.01-0.05); The rare earth oxide is obtained by mixing ytterbium oxide and erbium oxide in a mass ratio of 1:(0.01-0.05).

9. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to claim 1, characterized in that: The calcination conditions are: 500-700°C, 1-5h.

10. The method for preparing up-conversion luminescent materials by utilizing the resource recovery products of fluorine-containing chlorine waste acid according to claim 1, characterized in that: The fluorine ion leaching rate of the obtained up-conversion luminescent material is 0.001-0.01%.

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