La2O2CO3 hollow microspheres capable of efficiently adsorbing fluorine and phosphorus in water and preparation method of La2O2CO3 hollow microspheres

Abstract

The invention discloses La2O2CO3 hollow microspheres capable of efficiently adsorbing fluorine and phosphorus in a water body and a preparation method of the La2O2CO3 hollow microspheres, and belongs to the field of environmental protection. According to the preparation method, industrial-grade lanthanum compound precipitation powder is taken as a precursor, La2O2CO3 hollow microspheres are obtained through grinding, spray granulation and firing, proper dispersing agent types are selected in the spray granulation slurry preparation process, the pH of the slurry and the adding amount of the dispersing agents are controlled, and it is ensured that the slurry has good dispersity; in the spray drying process, particles and a binder in the slurry migrate to the surfaces of liquid drops due to the action of capillary force, and rigid shells are formed on the surfaces of the liquid drops, so that hollow particles are formed. The specific surface area of the obtained La2O2CO3 hollow microspheres is 50 m < 2 > / g or above, the saturated adsorption amount of fluorine adsorbed from a water body is 30 mg / g or above, and the saturated adsorption amount of phosphorus adsorbed from the water body is 300 mg / g or above.

Description

Technical Field

[0001] The present invention relates to La for efficiently absorbing fluorine and phosphorus in water 2 O 2 CO 3 The invention relates to hollow microspheres and a preparation method thereof, belonging to the field of environmental protection. Background Art

[0002] At present, the technologies for removing fluoride and phosphorus from water bodies mainly adopt chemical precipitation, biological method, adsorption method, etc. The adsorption method is simple to operate, low cost, high efficiency, especially lanthanum compounds have a miraculous effect on deep removal of fluoride and phosphorus from water bodies, and the adsorbed fluoride and phosphorus can be reused as resources.

[0003] Lanthanum compounds have a strong adsorption affinity for fluoride ions and phosphates in water, generating stable and insoluble lanthanum fluoride and lanthanum phosphate, respectively, and can quickly remove fluorine and phosphorus from water. The ability of lanthanum compounds to adsorb fluorine and phosphorus in water is closely related to their specific surface area. A large specific surface area means a high active site for adsorbing fluorine and phosphorus, and a large saturated adsorption capacity. The lanthanum chloride solution produced by the rare earth extraction and separation process uses ammonium bicarbonate solution, a mixed solution of ammonium bicarbonate and ammonia water, and an oxalic acid solution as precipitants. The La prepared by precipitation method 2 (CO 3 ) 3 、La(OH)CO 3 and La 2 (C 2 O 4 ) 3 Powders are conventional products. They are not easily soluble in water, have stable chemical properties, and are non-toxic. These three types of precipitated powders can be used to prepare La after being burned at 400℃-700℃. 2 O 2 CO 3 However, since there are no strict requirements on the specific surface areas of the three precipitated powders in industrial production, the prepared La 2 O 2 CO 3 The specific surface area of ​​powder products is relatively low, and the saturated adsorption capacity of fluorine and phosphorus from water is relatively low, while the high specific surface area La 2 O 2 CO 3 It has certain physical and chemical properties, as well as high biological activity, bioabsorbability and good biocompatibility, and has good application prospects in the fields of water purification, drug sustained-release and controlled-release, catalyst carriers, etc.

[0004] Patent CN110694583 B invented a preparation method and application of a magnetic recyclable lanthanum carbonate dephosphorus adsorbent. The invention has a strong adsorption and removal effect on high-concentration and low-concentration phosphorus in water bodies. The removal rate of phosphorus in water bodies reaches 99.9%, and the maximum saturated adsorption capacity of the adsorbent reaches 134.82 mg / g. The patent uses trimesic acid as a precipitant to obtain co-precipitated trimesic acid rare earth and iron, but the trimesic acid rare earth and iron need to be burned twice to obtain a magnetic lanthanum carbonate dephosphorus adsorbent, which increases the process steps and energy consumption. Patent CN117443338 A invented a porous mesh lanthanum carbonate dephosphorus adsorbent and its preparation method and application. A lanthanum-based compound, an organic polymer compound and a solvent are mixed, and a solid mixture is obtained after freezing. The solid mixture is vacuum freeze-dried and pyrolyzed in turn to obtain a porous mesh lanthanum carbonate dephosphorus adsorbent with a maximum saturated adsorption capacity of 93.1-100 mg / g. The method uses a freezing method and has high production costs. Patent CN105749892B invented a method for preparing a sea urchin-shaped microsphere lanthanum carbonate adsorbent for water phosphorus removal. Lanthanum nitrate and trimesic acid were reacted in a constant temperature shaker to obtain a microsphere adsorbent precursor, which was then calcined to obtain a sea urchin-shaped microsphere lanthanum carbonate adsorbent. The adsorbent has a good water phosphorus removal effect and can remove phosphorus from water to below 5μg / L. The phosphorus removal rate is more than 99%, and the maximum saturated adsorption capacity is as high as 255.72mg / g. However, the amount of organic reagent trimesic acid used is large, the concentration of the reaction reagent is relatively dilute, and the preparation cost is high. Patent CN103037870B invented lanthanum carbonate alkali, lanthanum carbonate alkali, and its manufacturing method and use. The invented lanthanum carbonate alkali has 20m 2 / g to 40m 2 / g BET surface area. The phosphate binding capacity of lanthanum oxycarbonate is significantly higher than that of common lanthanum carbonate. The invention is used to treat patients with hyperphosphatemia.

[0005] Zhang Tao et al. reported the performance of lanthanum carbonate granules in removing fluoride from water. It has a good defluorination effect in water with a pH value of 3-10, with a fluoride ion removal rate of 94.5% to 98.0%, and a saturated adsorption capacity of 22.47 mg / g. 2 O 3 Place in air with humidity greater than 60% and CO 2 After full contact and aging for 30 days, La 2 O 2 CO 3 However, this method has a long reaction time and is not easy to realize industrial production.

[0006] La 2 O 2 CO 3Powder has been used in the field of water purification as a special agent for adsorbing fluorine and phosphorus in water, and has achieved certain water purification effects. In order to further improve La 2 O 2 CO 3 The saturated adsorption capacity of fluorine and phosphorus by the powder, the above patents and literature use various methods to increase the La 2 O 2 CO 3 The specific surface area of ​​the powder is increased, and the active sites are increased. However, the method used has the disadvantages of high preparation cost and long cycle, which limits the industrial production application. The applicant found that the hollow microsphere compound prepared by combining spray granulation and calcination technology has high specific surface area and active sites, and has the characteristics of low production cost, continuous production, and controllable hollow microsphere particle size. The technology is used to prepare La 2 O 2 CO 3 The key technology for hollow microspheres to control the dispersion stability of lanthanum compound slurry is that only highly dispersed slurry can be used to prepare hollow structure materials with high sphericity through spray granulation method. Summary of the invention

[0007] In order to solve the problems in the prior art, the present invention proposes a La 2 O 2 CO 3 Hollow microspheres and preparation methods thereof.

[0008] The purpose of the present invention is achieved through the following technical solutions.

[0009] La that efficiently adsorbs fluorine and phosphorus in water 2 O 2 CO 3 A method for preparing hollow microspheres, characterized in that the method comprises the following steps:

[0010] 1) gradually adding lanthanum compound precipitate powder to deionized water and dispersant and grinding, maintaining the pH of the suspension within a set range during the grinding process, adding a binder to the suspension after grinding, and obtaining a slurry required for spray granulation after high-speed dispersion;

[0011] 2) Preparation of hollow microspheres: starting a spray granulator, conveying the slurry into the spray granulator at a uniform speed, collecting the powder in a collector, and obtaining hollow microspheres of lanthanum compound;

[0012] 3) The hollow microspheres of lanthanum compound are burned to obtain La 2 O 2 CO 3 Hollow microspheres.

[0013] According to some embodiments of the present invention, in step 1), the dispersant is a composite of an anionic dispersant and a non-ionic dispersant, and the dispersant is a mixture of ammonium polyacrylate and polyethylene glycol (PEG4000) in a mass ratio of 1:1 or a mixture of ammonium polymethacrylate and polyethylene glycol (PEG4000) in a mass ratio of 1:1, and the pH of the suspension is maintained at 8.5-9.5 during the grinding process.

[0014] According to some embodiments of the present invention, the grinding in step 1) means grinding until the particle size of the powder in the suspension is less than 200 nm.

[0015] According to some embodiments of the present invention, the precipitated powder of the lanthanum compound in step 1) is La(OH)CO 3 ,La 2 (CO 3 ) 3 or La 2 (C 2 O 4 ) 3 One of them.

[0016] According to some embodiments of the present invention, in step 1), the mass ratio of deionized water to dispersant is 0.5-1:0.001; the mass ratio of the precipitated lanthanum compound powder to the dispersant is 1:0.001 after deducting free water and crystal water; and the mass ratio of the dispersant to the binder is 1:20.

[0017] According to some embodiments of the present invention, in step 1), the binder is polyvinyl alcohol (PVA).

[0018] According to some embodiments of the present invention, in step 2), the inlet temperature of the spray granulator is controlled at 150°C-180°C.

[0019] According to some embodiments of the present invention, in step 3), the burning temperature is 470° C.-550° C., and the burning time is 3 h-5 h.

[0020] The present invention also provides a La prepared by the method 2 O 2 CO 3 Hollow microspheres, the La 2 O 2 CO 3 Hollow microsphere diameter D 50 The shell thickness is 20 μm-35 μm, the shell thickness is 100 nm-200 nm, and the specific surface area is 50 m 2 / g or above.

[0021] The present invention also provides the La 2 O 2 CO 3Application of hollow microspheres in adsorbing fluoride or phosphorus in water.

[0022] The core of the preparation method of the present invention is: 1) in order to improve the dispersion stability of industrial-grade lanthanum compound precipitate powder in suspension, the dispersant added in the grinding process is selected to be a composite of anionic dispersant and nonionic dispersant; the nonionic dispersant PEG4000 has the function of increasing steric hindrance, which blocks the collision and agglomeration degree between the lanthanum compound precipitate powder particles; the anionic dispersant ammonium polyacrylate or ammonium polymethacrylate COO - The groups are completely dissociated, which increases the ζ potential of the suspension, increases the negative charge on the surface of the powder particles, and improves the dispersion stability of the powder in the suspension. Therefore, the pH of the suspension is maintained at 8.5-9.5 during the grinding process. 2) Since the maximum saturation capacity of the powder adsorbing the dispersant decreases with the increase of pH, when the pH value of the suspension is greater than 8.5, the surface charge of the particles is negative, and COO - The groups are completely dissociated, so the adsorption of dispersants on the particle surface only occurs on a few positive sites, and the saturated capacity of particles to adsorb dispersants is low. When excessive dispersants are added, the excessive dispersants cause an increase in the ionic strength of the suspension, destroying the stability of the suspension. Therefore, controlling the amount of dispersant added is critical to obtaining a slurry with stable dispersion; 3) During the spray drying process of a slurry with good dispersion, due to the action of capillary forces, the particles and binder migrate to the surface of the droplets and form a rigid shell on the surface of the droplets, resulting in the formation of hollow particles; 4) Due to the porosity and large specific surface area of ​​hollow microspheres, they have a good effect in adsorbing fluorine and phosphorus in water. The larger the specific surface area, the higher the saturated adsorption capacity of fluorine and phosphorus. Therefore, choosing an appropriate calcination temperature for lanthanum compound hollow microspheres is critical, both to ensure that the lanthanum compound is completely converted into La 2 O 2 CO 3 , and have a high-strength shell and high porosity, and ensure that the dispersant and binder are completely decomposed, as well as La 2 O 2 CO 3 The hollow microspheres do not collapse or break in water, because the high burning temperature will increase the La 2 O 2 CO 3 The particles agglomerate and the specific surface area of ​​the hollow microspheres decreases; when the calcination temperature is greater than 727℃, La 2 O 2 CO 3 Can be decomposed into La 2 O 3 and CO 2 5) La 2 O 2 CO 3Hollow microspheres can provide more active sites and improve the ability to adsorb fluorine and phosphorus. The fluoride ions and phosphates adsorbed on the surface of hollow microspheres exchange ions with the elements in the microspheres through chemical reactions, or the fluoride ions and phosphates enter the inner surface of the porous material, thereby achieving the purpose of removing fluorine and phosphorus. 2 O 2 CO 3 The hollow microspheres adsorb fluoride and phosphorus in water bodies in the pH range of 3-8. When the pH value of the water body is 3, the surface of the hollow microspheres is positively charged. At this time, the hollow microspheres are easy to combine with fluoride ions and phosphates in the water body. 3+ It has a strong affinity with fluoride ions and phosphates in water, thus achieving the purpose of adsorbing and removing fluoride and phosphorus in water.

[0023] The advantages and effects of the present invention are:

[0024] (1) La prepared by the present invention 2 O 2 CO 3 Hollow microspheres have a high specific surface area and will provide an industrial production technology for applications in sewage purification, drug sustained-release and controlled-release bodies, catalyst carriers, and other fields;

[0025] (2)La 2 O 2 CO 3 Hollow microspheres have a high saturation capacity for adsorbing fluoride ions and phosphates in water, and can deeply remove fluoride and phosphorus in water. They also have a certain ability to remove arsenic, selenium, antimony, chromium and other metal ions in water.

[0026] (3) Hollow microspheres are easily dispersed in water, increasing the La 2 O 2 CO 3 The hollow microspheres have a higher probability of contacting fluorine and phosphorus in water, thus shortening the reaction time of removing fluorine and phosphorus from water.

[0027] (4) Using La 2 O 2 CO 3 The hollow microspheres adsorb fluorine or phosphorus in water, and after saturation, they can be further reacted with hydrofluoric acid or phosphoric acid to prepare applicable lanthanum fluoride or lanthanum phosphate;

[0028] (5) The present invention adopts spray granulation technology to prepare La 2 O 2 CO 3 The production process of hollow microspheres is simple, green and environmentally friendly, with low production costs, making it easy to achieve industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1Example 1La(OH)CO 3 SEM images of hollow microspheres;

[0030] Figure 2 Example 1La(OH)CO 3 XRD pattern of hollow microspheres;

[0031] Figure 3 Example 1La of the present invention 2 O 2 CO 3 SEM images of hollow microspheres;

[0032] Figure 4 Example 1La of the present invention 2 O 2 CO 3 XRD pattern of hollow microspheres. DETAILED DESCRIPTION

[0033] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0034] Example 1

[0035] (1)La(OH)CO 3 Slurry preparation: Add 100L deionized water, 0.05kg ammonium polyacrylate and 0.05kg PEG4000 into the sand mill dispersion tank, stir and disperse evenly, then start the sand mill and gradually add 100kg La(OH)CO 3 The pH value of the suspension was controlled at 9 during the grinding process. When the particle size of the powder in the suspension was less than 200 nm, the grinding was stopped and the suspension was input into the spray granulation dispersion tank. 2 kg of PVA was added and after high-speed dispersion, a granulated powder containing 49.48% La(OH)CO 3 Spray granulation slurry.

[0036] (2)La(OH)CO 3 Preparation of hollow microspheres: Turn on the spray granulator, control the inlet temperature at 150 °C, transport the slurry to the spray granulator at a uniform speed, collect the powder in the collector, and obtain La(OH)CO 3 Hollow microspheres. Figure 1 The obtained La(OH)CO 3 SEM image of hollow microspheres. Figure 2 The obtained La(OH)CO 3 XRD diagram of hollow microspheres; it can be seen from the figure that the La(OH)CO 3The microspheres consist of particles smaller than 200 nm and nanopores forming a shell. The spherical particles are monodispersed and no collapse or breakage is observed. The obtained La(OH)CO 3 XRD patterns of hollow microspheres and orthorhombic La(OH)CO 3 It complies with the standard card (JCPDS#49-0981).

[0037] (3)La 2 O 2 CO 3 Preparation of hollow microspheres: La(OH)CO 3 The hollow microspheres were calcined at 500 °C for 4 h to obtain La 2 O 2 CO 3 Hollow microspheres. Figure 3 For the income La 2 O 2 CO 3 SEM image of hollow microspheres. Figure 4 For the income La 2 O 2 CO 3 XRD pattern of hollow microspheres shows that the obtained La 2 O 2 CO 3 The hollow microspheres consist of particles smaller than 200 nm and nanopores forming a shell. The spherical particles are monodispersed and no collapse or breakage is observed. 2 O 2 CO 3 XRD patterns of hollow microspheres and La 2 O 2 CO 3 The standard card (PDF#48-1113) is consistent.

[0038] For the income 2 O 2 CO 3 The hollow microspheres were characterized by using BT-9300ST laser particle size analyzer to measure the particle size, focusing ion beam scanning electron microscope to measure the wall thickness, BET method to measure the specific surface area, fluoride ion electrode to measure the saturated adsorption of fluoride in water, and ammonium molybdate spectrophotometry (GB 11893-89) to measure the saturated adsorption of phosphorus in water.

[0039] Characterization and test results are as follows: Example 1 obtained La 2 O 2 CO 3 Hollow microsphere diameter D 50 The shell thickness is 185 nm and the specific surface area is 58.9 m 2 / g, the saturated adsorption capacity of fluorine from water is 31.6mg / g, and the saturated adsorption capacity of phosphorus from water is 310mg / g.

[0040] Example 2

[0041] (1)La 2 (CO 3 ) 3 Slurry preparation: Add 100L deionized water, 0.075kg ammonium polymethacrylate and 0.075kg PEG4000 into the sand mill dispersion tank, stir and disperse evenly, then turn on the sand mill and gradually add 150kg La 2 (CO 3 ) 3 The pH value of the suspension was controlled at 9.5 during the grinding process. When the particle size of the powder in the suspension was less than 200 nm, the grinding was stopped and the suspension was input into the spray granulation dispersion tank. 3 kg of PVA was added and after high-speed dispersion, a granulated powder containing 59.25% La was obtained. 2 (CO 3 ) 3 Spray granulation slurry;

[0042] (2)La 2 (CO 3 ) 3 Preparation of hollow microspheres: Turn on the spray granulator, control the inlet temperature at 170°C, transport the slurry to the spray granulator at a uniform speed, collect the powder in the collector, and obtain La 2 (CO 3 ) 3 Hollow microspheres.

[0043] (3)La 2 O 2 CO 3 Preparation of hollow microspheres: La 2 (CO 3 ) 3 The hollow microspheres were calcined at 470 °C for 3 h to obtain La 2 O 2 CO 3 Hollow microspheres.

[0044] The same characterization and testing methods as in Example 1 were used. 2 O 2 CO 3 Hollow microsphere indicators are as follows: La 2 O 2 CO 3 Hollow microsphere diameter D 50 The shell thickness is 125 nm and the specific surface area is 56 m 2 / g, the saturated adsorption capacity of fluorine from water is 30.5mg / g, and the saturated adsorption capacity of phosphorus from water is 306mg / g.

[0045] Example 3

[0046] (1)La 2 (C 2 O 4 ) 3 Slurry preparation: Add 100L deionized water, 0.1kg ammonium polyacrylate and 0.1kg PEG4000 into the sand mill dispersion tank, stir and disperse evenly, then turn on the sand mill and gradually add 200kg La 2 (C 2 O 4 ) 3 The pH value of the suspension was controlled at 9 during the grinding process. When the particle size of the powder in the suspension was less than 200 nm, the grinding was stopped and the suspension was input into the spray granulation dispersion tank. 4 kg of PVA was added and after high-speed dispersion, a granulated powder containing 65.75% La was obtained. 2 (C 2 O 4 ) 3 Spray granulation slurry;

[0047] (2)La 2 (C 2 O 4 ) 3 Preparation of hollow microspheres: Turn on the spray granulator, control the inlet temperature at 180°C, transport the slurry to the spray granulator at a uniform speed, collect the powder in the collector, and obtain La 2 (C 2 O 4 ) 3 Hollow microspheres.

[0048] (3)La 2 O 2 CO 3 Preparation of hollow microspheres: La 2 (C 2 O 4 ) 3 The hollow microspheres were calcined at 550℃ for 5h to obtain La 2 O 2 CO 3 Hollow microspheres.

[0049] The same characterization and testing methods as in Example 1 were used to obtain La 2 O 2 CO 3 Hollow microsphere indicators are as follows: La 2 O 2 CO 3Hollow microsphere diameter D 50 The shell thickness is 28.2 μm, the shell thickness is 145 nm, and the specific surface area is 51.2 m 2 / g, the saturated adsorption capacity of fluorine from water is 30.2mg / g, and the saturated adsorption capacity of phosphorus from water is 302mg / g.

[0050] Comparative Example 1

[0051] 0.05 kg of ammonium polyacrylate was used to replace 0.05 kg of ammonium polyacrylate and 0.05 kg of PEG4000, and the other steps were the same as those in Example 1. During the grinding process, the powder particle size in the suspension of Comparative Example 1 did not reach the powder particle size control index in the suspension of Example 1, and the minimum powder particle size in the suspension of Comparative Example 1 could only reach 600 nm. The suspension obtained in Comparative Example 1 was prepared according to the steps of Example 1 to prepare La 2 O 2 CO 3 Hollow microspheres.

[0052] Comparative Example 1 obtained La 2 O 2 CO 3 Hollow microspheres were used as adsorbents for fluorine and phosphorus adsorption from water. The same characterization and testing methods as in Example 1 were used. The La 2 O 2 CO 3 Hollow microspheres D 50 The surface area is 31.2 μm and the specific surface area is 40.56 m 2 / g, the saturated adsorption capacity of fluorine from water is 23.62mg / g, and the saturated adsorption capacity of phosphorus from water is 213.46mg / g.

[0053] Example 1 obtained La 2 O 2 CO 3 The specific surface area of ​​hollow microspheres is significantly higher than that of La obtained in Comparative Example 1. 2 O 2 CO 3 Hollow microspheres, Example 1La 2 O 2 CO 3 The saturated adsorption amount of fluorine or phosphorus from water by the hollow microspheres is higher than that in Comparative Example 1.

[0054] Comparative Example 2

[0055] 0.05 kg PEG4000 was used to replace 0.05 kg ammonium polyacrylate and 0.05 kg PEG4000, and the other steps were the same as in Example 1. During the grinding process, the minimum particle size of the powder in the suspension of Comparative Example 2 could only reach 1000 nm. The suspension obtained in Comparative Example 2 was prepared according to the steps of Example 1 to prepare La2 O 2 CO 3 Hollow microspheres.

[0056] Comparative Example 2 obtained La 2 O 2 CO 3 Hollow microspheres were used as adsorbents for fluorine and phosphorus adsorption from water. The same characterization and testing methods as in Example 1 were used. The La 2 O 2 CO 3 Hollow microspheres D 50 The surface area is 30.38 μm and the specific surface area is 20.65 m 2 / g, the saturated adsorption capacity of fluorine from water is 15.67mg / g, and the saturated adsorption capacity of phosphorus from water is 118.86mg / g.

[0057] Example 1 obtained La 2 O 2 CO 3 The specific surface area of ​​hollow microspheres is significantly higher than that of La obtained in Comparative Example 2. 2 O 2 CO 3 Hollow microspheres, Example 1La 2 O 2 CO 3 The saturated adsorption amount of fluorine or phosphorus from water by the hollow microspheres is higher than that of Comparative Example 2.

[0058] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing La2O2CO3 hollow microspheres for efficiently absorbing fluorine and phosphorus in water, characterized in that the method comprises the following steps: 1) gradually adding lanthanum compound precipitate powder to deionized water and dispersant and grinding, maintaining the pH of the suspension within a set range during the grinding process, adding a binder to the suspension after grinding, and obtaining a slurry required for spray granulation after high-speed dispersion; 2) Preparation of hollow microspheres: starting a spray granulator, conveying the slurry into the spray granulator at a uniform speed, collecting the powder in a collector, and obtaining hollow microspheres of lanthanum compound; 3) The lanthanum compound hollow microspheres are calcined to obtain La2O2CO3 hollow microspheres.

2. The method for preparing La2O2CO3 hollow microspheres according to claim 1, characterized in that: In step 1), the dispersant is a composite of an anionic dispersant and a nonionic dispersant, and the dispersant is a mixture of ammonium polyacrylate and polyethylene glycol (PEG400) in a mass ratio of 1:1 or a mixture of ammonium polymethacrylate and polyethylene glycol (PEG4000) in a mass ratio of 1:

1. The pH of the suspension is maintained at 8.5-9.5 during the grinding process.

3. The method for preparing La2O2CO3 hollow microspheres according to claim 1, characterized in that: The grinding in step 1) means grinding until the particle size of the powder in the suspension is less than 200 nm.

4. The method for preparing La2O2CO3 hollow microspheres according to claim 1, characterized in that: In step 1), the precipitated lanthanum compound powder is one of La(OH)CO3, La2(CO3)3 or La2(C2O4)3.

5. The method for preparing La2O2CO3 hollow microspheres according to claim 1, characterized in that: In step 1), the mass ratio of deionized water to dispersant is 0.5-1:0.001; the mass ratio of lanthanum compound precipitate powder to dispersant is 1:0.001 after deducting free water and crystal water; and the mass ratio of dispersant to binder is 1:

20.

6. The method for preparing La2O2CO3 hollow microspheres according to claim 1, characterized in that: In step 1), the binder is polyvinyl alcohol (PVA).

7. The method for preparing La2O2CO3 hollow microspheres according to claim 1, characterized in that: In step 2), the inlet temperature of the spray granulator is controlled at 150°C-180°C.

8. The method for preparing La2O2CO3 hollow microspheres according to claim 1, characterized in that: In step 3), the calcination temperature is 470° C.-550° C., and the calcination time is 3 h-5 h.

9. La2O2CO3 hollow microspheres prepared by the method according to any one of claims 1 to 8, wherein the particle size D of the La2O2CO3 hollow microspheres is 50 The shell thickness is 20 μm-35 μm, the shell thickness is 100 nm-200 nm, and the specific surface area is 50 m 2 / g or above.

10. Use of the La2O2CO3 hollow microspheres according to claim 9 for adsorbing fluorine or phosphorus in water.

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