Preparation method of metal carbonate

Abstract

The invention provides a preparation method of metal carbonate. The preparation method comprises a coprecipitation method and a conversion method. According to the coprecipitation method or the conversion method, the target product can be prepared in a relatively short time at normal temperature without participation of an auxiliary agent, and the drying process of the target product is simple. According to the two methods, the problems that high-temperature and high-pressure hydrothermal conditions are needed, freeze drying is needed in the drying process, polyethylene glycol and the like need to be used as auxiliaries in the preparation process, the reaction time is long, the preparation conditions are complex and the like in an existing method are remarkably solved.

Description

Technical Field

[0001] The invention relates to a preparation method of a type of metal carbonate, and relates to the technical field of functional material preparation. Background Art

[0002] Phosphorus plays an important role in regulating energy metabolism, influencing bone development, and promoting brain growth. Similarly, aquatic plants absorb phosphorus from water for growth and development. However, excessive phosphorus levels in water can cause a series of ecological and environmental problems, leading to water pollution. Phosphorus is present in human waste such as fertilizers, detergents, and pesticides, and subsequently enters rivers, lakes, and groundwater. When phosphorus concentrations in water exceed certain limits, eutrophication can easily occur. This occurs when the amount of phosphorus available to organisms in the water exceeds their demand, leading to the proliferation of eutrophic organisms such as algae, resulting in algal blooms. Excessive algal growth depletes oxygen in the water, turning oxygen-rich areas into oxygen-deficient areas, disrupting the balance of the aquatic ecosystem and threatening the survival of aquatic life. Furthermore, drinking or coming into contact with water containing high phosphorus concentrations can lead to various health problems. For example, long-term exposure to high-phosphorus water sources increases the incidence of kidney stones and urinary stones; phosphorus also reacts with organic matter in water bodies to form harmful chemicals, posing a potential carcinogenic risk to the human body.

[0003] Rare earth ions bind specifically to phosphorus due to their electron configuration, ionic radius matching, and coordination chemistry. Their interaction occurs through electron transfer or the formation of coordination bonds. Rare earth carbonates can reduce phosphorus concentrations in water to safe levels in a relatively short period of time. Their high adsorption capacity and rapid adsorption rate make them ideal phosphorus removal agents. Furthermore, rare earth carbonates demonstrate excellent removal efficiency for various forms of phosphorus (inorganic and organic), demonstrating their potential for widespread application.

[0004] Currently, there are few studies on bimetallic carbonate [AnLn(CO3)2·xH2O] (An represents an alkali metal element, and Ln represents a rare earth element) adsorbents. Among the several documents on the preparation of bimetallic carbonates disclosed in the prior art, patent document 201811525445.6 discloses a method for preparing a sodium lanthanum carbonate dephosphorus adsorbent. The method is prepared by a high-temperature hydrothermal method, which requires the use of high-temperature equipment such as a hydrothermal kettle and the reaction in the presence of an ethylene glycol auxiliary agent. The single preparation amount is small, and the product drying requires freeze-drying, which is a complicated operation. + =Li +,Na + ,K + ,Cs + ,NH 4+ ,and Ln 3+ =La 3+ ,Nd 3+ ,Eu 3+ ,Dy 3+ The preparation method disclosed in the disclosure uses a high carbonate / rare earth ratio, and the target product needs to be prepared under a high carbonate excess. At the same time, the preparation time is relatively long (more than 82 days). Summary of the Invention

[0005] In response to the above problems, the present invention provides a method for preparing a polymetallic carbonate dephosphorization adsorbent with a simple preparation method and low preparation requirements.

[0006] The preparation method of the polymetallic carbonate represented by formula (1) is a coprecipitation method or a conversion method;

[0007] An x Ln(CO3) 1.5+x / 2 ·nH2O(1)

[0008] Wherein, An represents an alkali metal element or ammonium ion, such as Li, Na, K, Rb, Cs, NH4 + ;

[0009] Ln represents a rare earth metal element, for example, one of La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium), Sc (scandium), and Y (yttrium), or a combination of two or more elements;

[0010] x is a number from 0.1 to 1; for example, a number from 0.2 to 0.8, such as a number from 0.3 to 0.7;

[0011] n is a number from 1 to 20; for example, a number from 3 to 18, such as a number from 5 to 15;

[0012] The coprecipitation method comprises the following steps:

[0013] Add the carbonate alkaline solution to the rare earth salt solution, stir at 0-60°C for more than 1 hour, let it stand for more than 1 hour, and rinse the sample with water until the pH is 6-8;

[0014] The transformation method comprises the following steps:

[0015] Rare earth carbonate Ln2(CO3)3·xH2O is added to a carbonate or bicarbonate solution of An, ultrasonicated, and then allowed to stand at 0-70°C for more than 1 hour.

[0016] According to an embodiment of the present invention, the polymetallic carbonate represented by formula (1) is NaLa(CO3)2·nH2O, wherein n is 5 to 9, KLa(CO3)2·6H2O, NaEu(CO3)2·5H2O or NaDy(CO3)2·5H2O.

[0017] According to an embodiment of the present invention, the co-precipitation method includes: preparing 0.1-5 mol / L rare earth salt solution and 0.1-5 mol / L carbonate alkaline solution, adding the carbonate alkaline solution to the rare earth salt solution according to the molar concentration ratio of rare earth salt solution to carbonate alkaline solution of 1: (0.1-3), stirring at 0-60°C for 1-72h, standing for 1-48h, filtering the precipitate, washing it to a pH of 6-8, and drying it at room temperature.

[0018] According to an embodiment of the present invention, in the co-precipitation method, the rare earth salt solution includes halides (such as chlorides), nitrates, sulfates or hydrates of these salts of La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium), Sc (scandium), and Y (yttrium).

[0019] According to an embodiment of the present invention, in the co-precipitation method, the rare earth salt solution used can be a mixed solution of two or more rare earth elements or different salts of the same rare earth element.

[0020] According to an embodiment of the present invention, in the coprecipitation method, the carbonate alkaline solution may include a carbonate solution, a mixed solution of carbonate and alkaline soluble matter, a mixed solution of carbonate and bicarbonate, a mixed solution of bicarbonate and alkaline soluble matter, etc. The carbonate alkaline solution refers to a solution containing carbonate ions (CO3 2- ) is an alkaline solution maintained at a certain concentration; the carbonate includes sodium carbonate, potassium carbonate, ammonium carbonate, lithium carbonate, cesium carbonate, and rubidium carbonate; the bicarbonate includes sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, lithium bicarbonate, cesium bicarbonate, and rubidium bicarbonate; the alkaline soluble substance includes lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, ammonia water, or sodium acetate.

[0021] According to an embodiment of the present invention, in the co-precipitation method, the concentration of the rare earth salt solution is 0.1 to 5 mol / L, for example, 0.5 to 4 mol / L, such as 1 to 3 mol / L.

[0022] According to an embodiment of the present invention, in the co-precipitation method, the concentration of carbonate in the carbonate alkaline solution is 0.1-5 mol / L, 0.5-4 mol / L, such as 1-3 mol / L, and its pH is ≥8.

[0023] According to an embodiment of the present invention, in the co-precipitation method, the molar ratio of Ln to carbonate in the reaction system is 1:(1-4), for example, 1:(2-3).

[0024] According to an embodiment of the present invention, in the co-precipitation method, the addition rate of the carbonate alkaline solution needs to be controlled so that the slurry can continue to maintain fluidity without coagulation.

[0025] According to an embodiment of the present invention, in the co-precipitation method, the temperature of the solution during mixing and stirring is maintained at 15-40°C.

[0026] According to an embodiment of the present invention, in the co-precipitation method, the stirring time is 6 to 72 hours.

[0027] According to an embodiment of the present invention, in the co-precipitation method, the standing time is 0.5 to 2 days.

[0028] According to an embodiment of the present invention, in the co-precipitation method, the pH of the filtrate after washing the final product is within the range of 6 to 8.

[0029] According to an embodiment of the present invention, the transformation method comprises the following steps:

[0030] Rare earth carbonate Ln2(CO3)3·xH2O is added to a carbonate or bicarbonate solution of An and ultrasonicated for 1 to 10 minutes, then allowed to stand at 0-60°C for 6 hours to 10 days, and the precipitated product is filtered, washed and dried.

[0031] According to an embodiment of the present invention, in the conversion method, the rare earth carbonate Ln2(CO3)3·xH2O includes carbonates of La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium), Sc (scandium), and Y (yttrium). The rare earth carbonate can be prepared by itself or purchased.

[0032] According to an embodiment of the present invention, in the conversion method, the carbonate includes sodium carbonate, potassium carbonate, ammonium carbonate, lithium carbonate, cesium carbonate, and rubidium carbonate; the bicarbonate includes sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, lithium bicarbonate, cesium bicarbonate, and rubidium bicarbonate.

[0033] According to an embodiment of the present invention, in the conversion method, the concentration of the carbonate or bicarbonate solution is 0.1 to 5 mol / L, such as 0.5 to 4 mol / L, such as 1 to 3 mol / L.

[0034] According to an embodiment of the present invention, in the conversion method, the amount of carbonate or bicarbonate solution used is 10 to 50 ml of carbonate or bicarbonate solution with a concentration of 0.1 to 5 mol / L for 1 g of rare earth carbonate, for example, 20 to 40 ml of carbonate or bicarbonate solution with a concentration of 0.25 to 3 mol / L.

[0035] According to an embodiment of the present invention, in the conversion method, the standing time is 0.5 to 10 days.

[0036] According to an embodiment of the present invention, in the conversion method, the standing temperature is 15 to 65°C, for example, 20 to 50°C.

[0037] The multi-metal rare earth carbonate prepared by the above preparation method is in the form of nanosheets, so that the prepared nanomaterial is less affected by pH, has a large specific surface area and a high adsorption capacity.

[0038] Beneficial effects

[0039] The present invention provides a multi-metal carbonate adsorbent An x Ln(CO3) 1.5+x / 2 The preparation method of nH2O only requires a simple co-precipitation method or conversion method, and the preparation of the multi-metal carbonate adsorbent can be achieved without an excessive amount of carbonate solution. The co-precipitation method or conversion method can prepare the target product in a shorter time at room temperature without the participation of an auxiliary agent, and the drying process of the target product is simple. These two methods significantly improve the existing methods, such as the need for high temperature and high pressure hydrothermal conditions, the need for freeze drying during the drying process, the need for polyethylene glycol as an auxiliary agent during the preparation, the long reaction time, and the complex preparation conditions. The prepared multi-metal carbonate adsorbent has a faster adsorption rate, is less affected by the pH of the ambient water, and has a strong ability to resist competitive ions. It is a type of phosphorus removal adsorbent with certain application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The X-ray diffraction spectra of the comparative example and example samples are shown in FIG.

[0041] Figure 2 This is a scanning electron microscope image of the sample in Example 1. DETAILED DESCRIPTION

[0042] In order to further understand the present invention, the scheme of the present invention is described in detail below in combination with comparative examples and embodiments, but the present invention is not limited to these embodiments. Any other changes, replacements or combined simplifications made under the core guiding idea of the patent of the present invention are included in the scope of protection of the patent of the present invention.

[0043] Comparative Example 1

[0044] Purchased lanthanum carbonate hydrate La2(CO3)3·8H2O.

[0045] Example 1

[0046] Prepare 50 ml of 0.5 mol / L LaCl3 solution, slowly add 50 ml of 1.5 mol / L Na2CO3 solution, stir at 25°C for 24 hours, let stand for 24 hours, rinse with deionized water until the pH is neutral, and dry at room temperature to obtain Example Sample 1, whose structural formula is NaLa(CO3)2·nH2O, where n is 5 to 9. The scanning electron microscope image of Example Sample 1 is as follows: Figure 2 As shown in FIG. 1 , the surface morphology of Example 1 is flaky. The yield is 9.526 g, with a yield of 95.7%.

[0047] Example 2

[0048] Prepare 50 ml of a 1 mol / L LaCl₃ solution, slowly add 50 ml of a 3 mol / L K₂CO₃ solution, stir at 50°C for 24 hours, let stand for 48 hours, rinse with deionized water until the pH is neutral, and dry at room temperature to obtain Example Sample 2, with the structural formula KLa(CO₃)₂·6H₂O. The yield is 20.356 g, for a yield of 97.4%.

[0049] Example 3

[0050] Prepare 50 ml of a 0.5 mol / L LaCl₃ solution, slowly add 250 ml of a 1.5 mol / L NaHCO₃ solution, stir at 30°C for 6 h, let stand for 12 h, rinse with deionized water until the pH is neutral, and dry at room temperature to obtain Example Sample 3, with the structural formula NaLa(CO₃)₂·nH₂O, where n is 5 to 9. The yield is 9.701 g, for a yield of 97.5%.

[0051] Example 4

[0052] Prepare 50 ml of a 0.5 mol / L EuCl₃ solution, slowly add 50 ml of a 1 mol / L Na₂CO₃ solution, stir at 30°C for 6 h, let stand for 12 h, rinse with deionized water until the pH is neutral, and dry to obtain Example Sample 4, with the structural formula NaEu(CO₃)₂·5H₂O. The yield is 9.957 g, for a yield of 98.8%.

[0053] Example 5

[0054] 0.5 g of purchased La2(CO3)3·8H2O was weighed and placed in 20 ml of 1 mol / L Na2CO3 solution. After sonication for 5 minutes, the solution was allowed to stand at room temperature for 48 hours. The precipitate was filtered, washed to a neutral pH, and dried at room temperature to obtain Example Sample 5, with the structural formula NaLa(CO3)2·nH2O, where n is 5 to 9. The yield was 0.581 g, for a yield of 89.7%.

[0055] Example 6

[0056] Weigh 0.5 g of commercially available Dy(CO)2·2H2O and dissolve it in 20 ml of 0.25 mol / L Na2CO3 solution. After sonication for 5 minutes, the mixture was allowed to stand in a 45°C water bath for 48 hours. The precipitate was filtered, washed to a neutral pH, and dried at room temperature to obtain Example Sample 6, with the structural formula NaDy(CO)2·5H2O. The yield was 0.653 g, for a yield of 85.5%.

[0057] The X-ray diffraction spectra of Examples 1-6 and Comparative Examples are shown in Figure 2. Figure 1 As shown. Figure 1 It can be seen that the composition of the obtained embodiment sample is An x Ln(CO3) 1.5+x / 2 nH2O (refer to reference).

[0058] Test Example 1

[0059] 100 ml of a phosphorus-containing solution (phosphorus concentration 60 mg P / L) was placed in a conical flask, the pH of the solution was adjusted, 50 mg of the adsorbent prepared in the comparative example and the example was added, and the solution was placed on a shaker at a speed of 180 rpm for adsorption. The solution was filtered through a 0.045 μm filter membrane, and the phosphorus content in the sample was determined according to the molybdenum blue method (GB11893-89).

[0060] Table 1 Adsorption test results of comparative examples and examples

[0061]

[0062] By testing the adsorption amount of the samples at different times to compare the adsorption rate and adsorption saturation amount, it can be clearly seen that compared with the comparative example, the example sample has a faster adsorption rate within 24 hours and has a higher saturation adsorption amount.

[0063] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for preparing a polymetallic carbonate represented by formula (1), characterized in that: It is a co-precipitation method or a conversion method; An x Ln(CO3) 1.5+x / 2 ·nH2O(1) Wherein, An represents an alkali metal element or an ammonium ion; Ln represents a rare earth metal element; x is a number from 0.1 to 1; n is a number from 1 to 20; The coprecipitation method comprises the following steps: Add the carbonate alkaline solution to the rare earth salt solution, stir at 0-60°C for more than 1 hour, let it stand for more than 1 hour, and rinse the sample with water until the pH is 6-8; The transformation method comprises the following steps: Rare earth carbonate Ln2(CO3)3·xH2O is added to a carbonate or bicarbonate solution of An, ultrasonicated, and then allowed to stand at 0-70°C for more than 1 hour.

2. The method according to claim 1, characterized in that The polymetallic carbonate represented by formula (1) is NaLa(CO3)2·nH2O, wherein n is 5 to 9, KLa(CO3)2·6H2O, NaEu(CO3)2·5H2O or NaDy(CO3)2·5H2O.

3. The method according to claim 1 or 2, characterized in that The co-precipitation method includes: preparing 0.1-5 mol / L rare earth salt solution and 0.1-5 mol / L carbonate alkaline solution, adding the carbonate alkaline solution to the rare earth salt solution according to the molar concentration ratio of rare earth salt solution to carbonate alkaline solution of 1:(0.1-3), stirring at 0-60°C for 1-72 hours, standing for 1-48 hours, filtering and washing the precipitate to a pH of 6-8, and drying at room temperature.

4. The method according to any one of claims 1 to 3, characterized in that In the co-precipitation method, the rare earth salt solution includes halides, nitrates, sulfates or hydrates of La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium), Sc (scandium), and Y (yttrium).

5. The method according to any one of claims 1 to 4, characterized in that In the co-precipitation method, the concentration of the rare earth salt solution is 0.5 to 4 mol / L; Preferably, in the coprecipitation method, the concentration of carbonate in the carbonate alkaline solution is 0.5 to 4 mol / L; Preferably, in the coprecipitation method, the molar ratio of Ln to carbonate in the reaction system is 1:(1-4).

6. The method according to any one of claims 1 to 5, characterized in that The temperature of the solution mixing and stirring is maintained at 15-40°C; Preferably, the stirring time is 6 to 72 hours; Preferably, in the co-precipitation method, the standing time is 0.5 to 2 days.

7. The method according to claim 1 or 2, characterized in that The transformation method comprises the following steps: Rare earth carbonate Ln2(CO3)3·xH2O is added to a carbonate or bicarbonate solution of An and ultrasonicated for 1 to 10 minutes, then allowed to stand at 0-60°C for 6 hours to 10 days, and the precipitated product is filtered, washed and dried.

8. The method according to claim 7, characterized in that In the conversion method, the rare earth carbonate Ln2(CO3)3·xH2O includes carbonates of La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium), Sc (scandium), and Y (yttrium); Preferably, the carbonate includes sodium carbonate, potassium carbonate, ammonium carbonate, lithium carbonate, cesium carbonate, and rubidium carbonate; the bicarbonate includes sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, lithium bicarbonate, cesium bicarbonate, and rubidium bicarbonate.

9. The method according to claim 7 or 8, characterized in that In the conversion method, the concentration of the carbonate or bicarbonate solution is 0.5 to 4 mol / L; Preferably, the amount of carbonate or bicarbonate solution used is 10 to 50 ml of carbonate or bicarbonate solution with a concentration of 0.1 to 5 mol / L for 1 gram of rare earth carbonate.

10. The method according to any one of claims 7 to 9, characterized in that: In the transformation method, the standing time is 0.5 to 10 days; Preferably, in the conversion method, the standing temperature is 15 to 65°C.

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