Method for preparing UTSA-280 material from ardealite

Abstract

The invention belongs to the field of recycling of waste ardealite and green low-cost synthesis of metal-organic framework (MOF) materials, and discloses a method for preparing a UTSA-280 material from ardealite, which comprises the following steps: (1) carrying out dry reaction on squaric acid and a solid strong alkali compound under the mechanochemical action to obtain squarate; and (2) carrying out dry reaction on ardealite and the squarate obtained in the step (1) under the mechanochemical action again, and centrifuging, washing and drying the product after the reaction to obtain the UTSA-280 material. According to the invention, phosphogypsum is used as a raw material, and the classical important MOF material with high added value, namely UTSA-280, can be prepared through simple and convenient process treatment, such as a two-step mechanochemical reaction (such as a two-step ball milling method), and particularly, the MOF material can be prepared in a green and low-cost manner under the conditions of normal temperature and normal pressure. The invention provides a new way for upgraded chemical recycling of phosphogypsum.

Description

Technical Field

[0001] The present invention belongs to the field of recycling of waste phosphogypsum and green low-cost synthesis of metal-organic framework (MOF) materials. More specifically, it relates to a method for preparing UTSA-280 material from phosphogypsum, and realizes the recycling of waste phosphogypsum by means of mechanochemical reaction (such as ball milling). Background Art

[0002] Phosphogypsum is the main solid waste generated in the production process of wet-process phosphoric acid. Its main component is calcium sulfate dihydrate (CaSO4·2H2O), containing impurities such as phosphorus, fluorine and organic matters. Some phosphogypsum impurities also include heavy metals and radioactive impurities. Phosphogypsum is the solid waste generated by phosphochemical enterprises in the production of products such as phosphoric acid and phosphate fertilizers. It mainly comes from the wet reaction of sulfuric acid and phosphate rock. Usually, 4-5 tons of phosphogypsum are generated for every 1 ton of phosphoric acid produced. The comprehensive utilization of phosphogypsum mainly includes the following aspects. In the cement industry, phosphogypsum can be used as a cement retarder and for producing sulfuric acid and co-producing cement, which is also the largest application way of phosphogypsum. In terms of building materials, the resource utilization of phosphogypsum building materials mainly focuses on the production of gypsum products such as gypsum powder, gypsum board, gypsum block and gypsum brick. In terms of construction engineering basic materials: it is used as road base materials and filling aggregates in construction engineering basic materials. In the agricultural aspect, the utilization of phosphogypsum in agriculture is as a saline-alkali soil conditioner, sulfur, calcium and silicon fertilizers. In the fertilizer industry, the application of phosphogypsum in the fertilizer industry is for producing ammonium sulfate and potassium sulfate.

[0003] Due to the low comprehensive utilization rate of phosphogypsum, most phosphogypsum is stacked in open-air yards. Long-term stacking not only occupies a large amount of land resources, but also poses environmental pollution risks, such as groundwater pollution, soil acidification and air pollution, etc. In addition, the heavy metals and radioactive elements in phosphogypsum may enter the human body through the food chain, resulting in damage to organs such as the nervous system, bones and kidneys. The efficient resource treatment of phosphogypsum has become the focus of global attention. At present, the main treatment methods of phosphogypsum are divided into physical method, chemical method and heat treatment method. The physical method has complex process, high treatment cost and is easy to cause secondary pollution. The chemical method usually needs to add additives or modifiers (such as acids, alkalis and salts), and is not easy to be used on a large scale. The heat treatment method requires high-temperature calcination, with large energy consumption, complex process and high cost. Therefore, developing a green, environmentally friendly and low-energy-consuming method to degrade phosphogypsum and realizing the high-value utilization of phosphogypsum is a necessary way to reduce environmental pollution and achieve sustainable development.

[0004] Metal-organic framework (MOF) materials are a class of crystalline porous materials with a periodic network structure formed by the self-assembly of inorganic metal centers (i.e., metal ions or metal clusters) and bridging organic ligands. MOF materials have characteristics such as abundant active sites, adjustable pore structures, high specific surface areas and porosities, and adjustable chemical compositions and functions, and are widely used in fields such as gas storage and separation, catalysis, drug delivery, and chemical / biological sensing. For example, UTSA-280, as a supermicroporous MOF material with a unique all-rigid framework, shows great application prospects in the adsorption selectivity of ethylene / ethane. Currently, the main synthesis methods of UTSA-280 are hydrothermal method and ball milling method. Liangying Li et al. used the hydrothermal method, with calcium carbonate and squaric acid as raw materials, and reacted at 120 °C for 24 hours to prepare UTSA-280 material (Liangying Li, Lidong Guo, Siyu Pu, Jiawei Wang, Qiwei Yang, Zhiguo Zhang, Yiwen Yang, Qilong Ren, Sufian Alnemrat, Zongbi Bao, A calcium-based microporous metal-organic framework for efficient adsorption separation of light hydrocarbons, Chemical Engineering Journal 2019, 358, 446-455). This method has harsh reaction conditions (e.g., high temperature (120 °C) and high pressure (usually above 40 atmospheres)), time-consuming (usually more than 12 hours), and thus it is difficult to achieve the large-scale production of UTSA-280. Rui-Biao Lin et al. used the aqueous solution stirring method, with sodium squarate and calcium nitrate as raw materials, and stirred in the aqueous solution to prepare UTSA-280 material (Rui-Biao Lin, Libo Li, Hao-Long Zhou, Hui Wu, Chaohui He, Shun Li, Rajamani Krishna, Jinping Li, Wei Zhou, Banglin Chen, Nature Materials, 2018, 17, 1128-1133). The disadvantages of this method are the use of expensive disodium squarate as a precursor, the generation of a large amount of wastewater, and the low yield of UTSA-280 (74%).Yanshu Shi et al. used the wet ball milling method to prepare UTSA-280 with squaric acid and calcium oxide as raw materials and water as an auxiliary agent. The disadvantage of this method is that it is difficult for squaric acid and calcium oxide to directly undergo ball milling reaction and external water needs to be added. The solubility of squaric acid and calcium oxide in water is relatively low, and water is generated during the reaction of squaric acid and calcium oxide. The externally added water auxiliary agent is not conducive to the equilibrium reaction of forming UTSA-280. Therefore, there are significant challenges in synthesizing UTSA-280 efficiently and at low cost.

[0005] Phosphogypsum contains a large amount of calcium element, so it can be used as a calcium source to prepare calcium-based MOF materials, thus realizing the high-value utilization of phosphogypsum. At present, only one piece of literature has reported the synthesis of MOF materials using phosphogypsum as a precursor. Yimer et al. used phosphogypsum as a precursor to prepare three calcium-based MOF materials, including BMOF-2, Ca-BDC, and Ca-BTC (ZAli Mohammed Yimera, Ayalew H. Assena, Ikrame El Mghaimimia, Omar Lakbitaa, Karim Adila, b, Youssef Belmabkhout. Unlocking the potential of phosphogypsum waste: Unified synthesis of functional metal-organic frameworks and zeolite via a sustainable valorization route. Chemical Engineering Journal 2024, 479, 147902). However, this method requires a large amount of acid (such as hydrochloric acid), the reaction conditions are harsh (such as high temperature (120 °C) and high pressure (usually higher than 40 atmospheres)), consumes a large amount of organic solvents (such as ethanol), and is time-consuming (usually more than 12 hours), so it is difficult to achieve the large-scale use of phosphogypsum and the large-scale production of MOF. Therefore, if a green, efficient, mild reaction condition, non-consumptive organic solvent, and low-cost method can be developed to convert phosphogypsum into high-value-added MOF materials (such as UTSA-280), it will undoubtedly greatly promote the reuse of waste phosphogypsum. Summary of the Invention

[0006] In view of the above deficiencies or improvement requirements of the prior art, the purpose of the present invention is to provide a method for preparing UTSA-280 material from phosphogypsum. Using phosphogypsum as raw material, through a simple process treatment of two-step mechanochemical reaction (such as two-step ball milling method), specifically, squaric acid is first converted into squarate salt under strong alkaline environment through mechanochemical action (such as the mechanical force of ball milling), and then the squarate salt and phosphogypsum (especially waste phosphogypsum) can be used to prepare the classic and important high-value-added MOF material UTSA-280 through mechanochemical reaction, especially capable of preparing MOF materials greenly and at low cost under normal temperature and pressure conditions. The present invention provides a new way for the upgraded chemical recycling and reuse of phosphogypsum, and also provides a new method for the industrial preparation of high-value-added UTSA-280 material, which has important practical significance in environmental protection, efficient chemical recycling and sustainable development, and at the same time has the prospect of industrialization and resource utilization, in order to achieve a green economy chemistry.

[0007] To achieve the above object, according to one aspect of the present invention, there is provided a method for preparing UTSA-280 material from phosphogypsum, characterized by comprising the following steps:

[0008] (1) Performing a dry reaction on squaric acid and a solid strong base compound under mechanochemical action to obtain squarate salt;

[0009] (2) Performing a dry reaction on phosphogypsum and the squarate salt obtained in step (1) again under mechanochemical action, and centrifuging, washing and drying the product after the reaction to obtain UTSA-280 material.

[0010] As a further preference of the present invention, in step (1), the mechanochemical action is ball milling treatment;

[0011] In step (2), the mechanochemical action is ball milling treatment.

[0012] As a further preference of the present invention, in step (1), the molar ratio of the squaric acid to the solid strong base compound is 1 / 4 - 1 / 1.

[0013] As a further preference of the present invention, in step (1), the ball milling time of the ball milling treatment is 5 - 30 min, and the ball milling speed is 100 - 500 r / min.

[0014] As a further preference of the present invention, in step (1), the solid strong base compound is one or more of sodium hydroxide and potassium hydroxide;

[0015] Preferably sodium hydroxide.

[0016] As a further preference of the present invention, in step (2), the molar ratio of the squarate salt to the calcium sulfate dihydrate contained in the phosphogypsum is 1 / 2 - 2 / 1.

[0017] As a further preference of the present invention, in step (2), the ball milling time of the ball milling treatment is 5 to 30 min, and the ball milling speed is 100 to 500 r / min.

[0018] As a further preference of the present invention, in step (2), the phosphogypsum is waste phosphogypsum, and the mass percentage content of calcium sulfate dihydrate is preferably 95 wt% or more.

[0019] Through the above technical solution conceived by the present invention, compared with the prior art, the method of the present invention uses phosphogypsum to prepare UTSA-280 material through two-step dry force chemical reaction. Taking the mechanochemical action as an example of ball milling treatment, specifically, squaric acid and solid strong base compound are first put into a ball mill for dry ball milling, and squaric acid is converted into squarate; subsequently, the squarate is mixed with waste phosphogypsum and subjected to dry ball milling, and the squarate ion in the squarate reacts with the calcium ion in the phosphogypsum to generate UTSA-280. The method of the present invention has a high yield and can realize the efficient preparation of UTSA-280 material.

[0020] In the method of the present invention, squaric acid and solid strong base compound are first mixed for dry force chemical reaction, avoiding the use of organic solvents. The strong base compound reacts with squaric acid to form squarate; moreover, different from the limited access and purchase channels of squarate, the squaric acid and strong base compound adopted in the present invention are cheap and easily available and can be conveniently purchased through commercial channels. Subsequently, the squarate is mixed with phosphogypsum for mechanochemical reaction, and the squarate ion coordinates with the calcium ion to generate UTSA-280. The squarate ion in ionic form is easy to coordinate with the calcium ion in the phosphogypsum to form a complex. The present invention uses two-step mechanochemical reaction to convert phosphogypsum (especially waste phosphogypsum) into high-value-added UTSA-280, which has the advantages of being green and efficient, low cost, no generation of polluting gases, no use of organic solvents, high synthesis efficiency, high yield, easy large-scale production of UTSA-280, and the whole process can be carried out under normal temperature and pressure in an air atmosphere, etc., without the need for protective gases (such as nitrogen and hydrogen), providing a new solution for the upgraded chemical recycling of phosphogypsum to prepare UTSA-280 material.

[0021] Specifically, the present invention can achieve the following beneficial effects:

[0022] (1) Compared with traditional phosphogypsum recycling methods, such as the physical method which has complex processes, high treatment costs, and is prone to secondary pollution, and the heat treatment method which requires high-temperature calcination, high energy consumption, complex processes, and high costs, the present invention realizes the green and environmentally friendly recycling of phosphogypsum into UTSA-280 material. The steps are simple, the reaction is efficient, the cost is low, the energy consumption is low, and the product has unique advantages in the fields of gas storage and separation, catalysis, drug delivery, chemical / biological sensing, etc. Another example is that the chemical method usually requires adding additives or modifiers (such as acids, bases, and salts), etc., and is not easy to be used on a large scale. The present invention realizes the degradation of phosphogypsum to prepare UTSA-280 material without using additives, without the need for a large amount of acid / alkali treatment, is easy to scale up, and the added value of the product is high.

[0023] (2) Compared with traditional methods for preparing MOF from phosphogypsum, the present invention uses a two-step mechanochemical reaction to prepare MOF materials. Squaric acid hydrolyzes into squarate salts under mechanochemical action with strong base compounds. The squarate ions in ionic form are easy to coordinate with metal ions to form complexes, and form coordination bonds by reacting with calcium ions in phosphogypsum, thereby generating MOF. The present invention provides a new method for the low-cost preparation of MOF.

[0024] (3) Compared with traditional methods for preparing UTSA-280, such as the solution stirring method and the hydrothermal method, which use a large amount of solvents, require a high-temperature and high-pressure environment, have a long reaction time, a low reaction yield, and produce a large number of by-products, the present invention uses a two-step mechanochemical reaction to prepare UTSA-280 without using solvents. It can quickly and controllably complete the synthesis of UTSA-280 under normal temperature and pressure conditions. The reaction time is short, the yield is high, the operation method is simple, the external heat demand is reduced, the energy intake is reduced, and it has high social and economic benefits. The present invention provides a new strategy for the green preparation of UTSA-280.

[0025] In summary, the present invention uses a two-step mechanochemical reaction to green-upgrade and chemically recycle waste phosphogypsum to prepare UTSA-280 material, which is a new chemical recycling process for phosphogypsum, effectively improving the problem of harsh conditions for preparing UTSA-280 from phosphogypsum. The method for synthesizing UTSA-280F based on a two-step mechanochemical reaction under normal temperature and pressure is green and efficient, has simple equipment requirements, and low costs. It is expected to solve the problem of recycling and reusing a large amount of phosphogypsum while producing high-value-added UTSA-280 material, meeting the development goals of green, low-carbon, and sustainable. Description of the Drawings

[0026] Figure 1 For the X-ray powder diffraction pattern, infrared spectrum, and scanning electron microscope image of UTSA-280 in Example 1; among them, Figure 1 a in Figure 1wherein b in [description] is an infrared spectrogram, Figure 1 wherein c and d in [description] are scanning electron microscope images at different magnifications.

[0027] Figure 2 are the X-ray powder diffraction pattern, infrared spectrogram and scanning electron microscope images of UTSA-280 in Example 2; wherein, Figure 2 a in [description] is the X-ray powder diffraction pattern, Figure 2 b in [description] is the infrared spectrogram, Figure 2 wherein c and d in [description] are scanning electron microscope images at different magnifications.

[0028] Figure 3 are the X-ray powder diffraction pattern, infrared spectrogram and scanning electron microscope images of UTSA-280 in Example 3; wherein, Figure 3 a in [description] is the X-ray powder diffraction pattern, Figure 3 b in [description] is the infrared spectrogram, Figure 3 wherein c and d in [description] are scanning electron microscope images at different magnifications.

[0029] Figure 4 are the X-ray powder diffraction pattern and scanning electron microscope images of UTSA-280 in Example 4; wherein, Figure 4 a in [description] is the X-ray powder diffraction pattern, Figure 4 b in [description] is the scanning electron microscope image.

[0030] Figure 5 are the X-ray powder diffraction pattern and scanning electron microscope images of UTSA-280 in Example 5; wherein, Figure 5 a in [description] is the X-ray powder diffraction pattern, Figure 5 b in [description] is the scanning electron microscope image.

[0031] Figure 6 are the X-ray powder diffraction pattern, infrared spectrogram and scanning electron microscope images of UTSA-280 in Example 6; wherein, Figure 6 a in [description] is the X-ray powder diffraction pattern, Figure 6 b in [description] is the infrared spectrogram, Figure 6 wherein c and d in [description] are scanning electron microscope images at different magnifications.

[0032] Figure 7 are the X-ray powder diffraction pattern and infrared spectrogram of the product in Comparative Example 1; wherein, Figure 7 a in [description] is the X-ray powder diffraction pattern, Figure 7 b in [description] is the infrared spectrogram.

[0033] Figure 8 are the X-ray powder diffraction pattern and scanning electron microscope images of the product in Comparative Example 1; wherein,Figure 8 wherein a in Figure 8 is the X-ray powder diffraction pattern, and b in

[0034] Figure 9 are the X-ray powder diffraction pattern and scanning electron microscope image of the product in Comparative Example 2; wherein, Figure 9 a in Figure 9 is the X-ray powder diffraction pattern, and b in Detailed implementation mode

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] The phosphogypsum used in the following examples was purchased from Wuhan Aotelong Building Materials Co., Ltd., and the content of calcium sulfate dihydrate was 95 wt%.

[0037] [[ID=2,2]]All ball milling in the following examples was dry ball milling and was carried out in an air environment at normal temperature and pressure. The two-step ball milling process can be carried out successively in the same ball mill tank. Of course, the ball mill tank can also be replaced.

[0038] Example 1

[0039] ]](1) Add 11.4 g of squaric acid (0.1 mol) and 8.08 g of sodium hydroxide (0.2 mol) into a ball mill tank, ball mill for 10 min at a rotation speed of 300 r / min to obtain a light gray product.

[0040] (2) Weigh 18.123 g of phosphogypsum (the amount of substance of calcium sulfate dihydrate is 0.1 mol), stir and mix it with the above product, then ball mill for 10 min at a rotation speed of 300 r / min, centrifuge the product (specifically, add water to the ball mill tank after the reaction to dissolve and remove unreacted impurities, and then centrifuge to take the precipitate), wash and dry to obtain UTSA-280 material, and the yield is 99%.

[0041] Figure 1 wherein a in Figure 1 is the X-ray powder diffraction pattern of UTSA-280, and b in Figure 1 ​In it, c and d are the scanning electron microscope images of UTSA-280. From the X-ray powder diffraction pattern, it can be seen that UTSA-280 has significant characteristic diffraction peaks, indicating the successful synthesis of UTSA-280. The infrared spectrum shows that UTSA-280 has significant infrared characteristic absorption peaks, also indicating the successful synthesis of UTSA-280. The scanning electron microscope image shows that the morphology of UTSA-280 is a rod-like structure with a length of 10 - 20 μm.

[0042] Example 2

[0043] (1) Add 11.4 g of squaric acid (0.1 mol) and 4.04 g of sodium hydroxide (0.1 mol) into the ball milling tank, ball mill for 5 min at a rotation speed of 300 r / min to obtain a light gray product.

[0044] (2) Weigh 18.123 g of phosphogypsum (the amount of substance of calcium sulfate dihydrate is 0.1 mol), stir and mix it with the above product, then ball mill for 10 min at a rotation speed of 100 r / min, and centrifuge, wash, and dry the product to obtain the UTSA-280 material with a yield of 97%.

[0045] Figure 2 In it, a is the X-ray powder diffraction pattern of UTSA-280, Figure 2 In it, b is the infrared spectrum of UTSA-280, Figure 2 In it, c and d are the scanning electron microscope images of UTSA-280. From the X-ray powder diffraction pattern, it can be seen that UTSA-280 has significant characteristic diffraction peaks, indicating the successful synthesis of UTSA-280. The infrared spectrum shows that UTSA-280 has significant infrared characteristic absorption peaks, also indicating the successful synthesis of UTSA-280. The scanning electron microscope image shows that the morphology of UTSA-280 is an irregular rod-like structure with a length of 10 - 20 μm.

[0046] Example 3

[0047] (1) Add 11.4 g of squaric acid (0.1 mol) and 11.22 g of potassium hydroxide (0.2 mol) into the ball milling tank, ball mill for 10 min at a rotation speed of 100 r / min to obtain a light gray product.

[0048] (2) Weigh 36.246 g of phosphogypsum (the amount of substance of calcium sulfate dihydrate is 0.2 mol), stir and mix it with the above product, then ball mill for 10 min at a rotation speed of 300 r / min, and centrifuge, wash, and dry the product to obtain the UTSA-280 material with a yield of 99%.

[0049] Figure 3 In it, a is the X-ray powder diffraction pattern of UTSA-280, Figure 3where b is the infrared spectrum of UTSA-280, Figure 3 where c and d are the scanning electron microscope images of UTSA-280. From the X-ray powder diffraction pattern, it can be seen that UTSA-280 has significant characteristic diffraction peaks, indicating the successful synthesis of UTSA-280. The infrared spectrum shows that UTSA-280 has significant infrared characteristic absorption peaks, also indicating the successful synthesis of UTSA-280. The scanning electron microscope image shows that the morphology of UTSA-280 is an irregular rod-like structure with a length of 1 - 10 μm.

[0050] Example 4

[0051] (1) Add 11.4 g of squaric acid (0.1 mol) and 16.16 g of sodium hydroxide (0.4 mol) into a ball milling jar, ball mill for 10 min at a rotation speed of 500 r / min to obtain a light gray product.

[0052] (2) Weigh 18.123 g of phosphogypsum (the amount of substance of calcium sulfate dihydrate is 0.1 mol), stir and mix it with the above product, then ball mill for 5 min at a rotation speed of 500 r / min. Centrifuge, wash, and dry the product to obtain UTSA-280 material with a yield of 99%.

[0053] Figure 4 where a is the X-ray powder diffraction pattern of UTSA-280, Figure 4 where b is the scanning electron microscope image of UTSA-280. From the X-ray powder diffraction pattern, it can be seen that UTSA-280 has obvious characteristic diffraction peaks, indicating the successful synthesis of UTSA-280. From the scanning electron microscope image, it can be known that the morphology of UTSA-280 is a rod-like structure with a length of 1 - 20 μm.

[0054] Example 5

[0055] (1) Add 11.4 g of squaric acid (0.1 mol) and 8.08 g of sodium hydroxide (0.2 mol) into a ball milling jar, ball mill for 30 min at a rotation speed of 300 r / min to obtain a light gray product.

[0056] (2) Weigh 9.0615 g of phosphogypsum (the amount of substance of calcium sulfate dihydrate is 0.05 mol), stir and mix it with the above product, then ball mill for 10 min at a rotation speed of 100 r / min. Centrifuge, wash, and dry the product to obtain UTSA-280 material with a yield of 98%.

[0057] Figure 5 where a is the X-ray powder diffraction pattern of UTSA-280, Figure 5In it, b is the scanning electron microscope image of UTSA-280. From the X-ray powder diffraction pattern, it can be seen that UTSA-280 has obvious characteristic diffraction peaks, indicating the successful synthesis of UTSA-280. From the scanning electron microscope image, it can be known that the morphology of UTSA-280 is a rod-like structure with a length of about 10 μm.

[0058] Example 6

[0059] (1) Add 11.4 g of squaric acid (0.1 mol) and 8.08 g of sodium hydroxide (0.2 mol) into the ball milling tank, with a ball milling time of 20 min and a rotation speed of 300 r / min to obtain a light gray product.

[0060] (2) Weigh 18.123 g of phosphogypsum (the amount of substance of calcium sulfate dihydrate is 0.1 mol), stir and mix it with the above product, then ball mill for 20 min at a rotation speed of 300 r / min. Centrifuge, wash, and dry the product to obtain UTSA-280 material, with a yield of 97%.

[0061] Figure 6 In it, a is the X-ray powder diffraction pattern of UTSA-280, Figure 6 In it, b is the infrared spectrum of UTSA-280, Figure 6 In it, c and d are the scanning electron microscope images of UTSA-280. From the X-ray powder diffraction pattern, it can be seen that UTSA-280 has significant characteristic diffraction peaks, indicating the successful synthesis of UTSA-280. The infrared spectrum shows that UTSA-280 has significant infrared characteristic absorption peaks, also indicating the successful synthesis of UTSA-280. The scanning electron microscope image shows that the morphology of UTSA-280 is an irregular rod-like structure with a length of 10 - 40 μm.

[0062] Example 7

[0063] (1) Add 11.4 g of squaric acid (0.1 mol) and 8.08 g of sodium hydroxide (0.2 mol) into the ball milling tank, with a ball milling time of 30 min and a rotation speed of 300 r / min to obtain a light gray product.

[0064] (2) Weigh 18.123 g of phosphogypsum (the amount of substance of calcium sulfate dihydrate is 0.1 mol), stir and mix it with the above product, then ball mill for 30 min at a rotation speed of 100 r / min. Centrifuge, wash, and dry the product to obtain UTSA-280 material, with a yield of 99%.

[0065] Figure 7 In it, a is the X-ray powder diffraction pattern of UTSA-280, Figure 7In it, b is the infrared spectrum of UTSA-280. From the X-ray powder diffraction pattern, it can be seen that UTSA-280 has significant characteristic diffraction peaks, indicating the successful synthesis of UTSA-280. The infrared spectrum shows that UTSA-280 has significant infrared characteristic absorption peaks, which also indicates the successful synthesis of UTSA-280.

[0066] Comparative Example 1

[0067] 11.4 g of squaric acid (0.1 mol) and 18.123 g of phosphogypsum (the amount of substance of calcium sulfate dihydrate is 0.1 mol) were added to a ball mill jar, the rotation speed was 300 r / min, and the ball milling time was 10 min to obtain a pink-purple product.

[0068] Figure 8 In it, a is the X-ray powder diffraction pattern of the ball-milled product, Figure 8 In it, b is the scanning electron micrograph of the ball-milled product. From the X-ray powder diffraction pattern, it can be seen that the product is a mixture of squaric acid and phosphogypsum, and no UTSA-280 is generated. The scanning electron micrograph shows that the morphology of the product is irregularly stacked nanoparticles with a size of 10 - 900 nm.

[0069] Comparative Example 2

[0070] The phosphogypsum in Comparative Example 1 above was changed to anhydrous calcium sulfate (the amount of anhydrous calcium sulfate used was 0.1 mol), and the amounts of other raw materials and the settings of step parameters remained unchanged. The X-ray powder diffraction pattern and scanning electron micrograph of the product are as Figure 9 shown. From the X-ray powder diffraction pattern, it can be seen that the product is a mixture of squaric acid and anhydrous calcium sulfate, that is, no UTSA-280 is generated. The scanning electron micrograph shows that the morphology of the product is mainly irregularly stacked rod-like structures with a length of 0.1 - 3 μm.

[0071] The above embodiments are only examples. For example, in addition to ball milling, mechanochemical action can also be carried out by manual grinding.

[0072] It is easy for those skilled in the art to understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing UTSA-280 material from phosphogypsum, characterized in that, It includes the following steps: (1) Subject squaric acid and a solid strong base compound to a dry reaction under mechanochemical action to obtain a squarate; (2) Subject phosphogypsum and the squarate obtained in step (1) to a dry reaction again under mechanochemical action. After the reaction, centrifuge, wash, and dry the product to obtain the UTSA-280 material.

2. The method according to claim 1, characterized in that In step (1), the mechanochemical action is ball milling; In step (2), the mechanochemical action is ball milling.

3. The method according to claim 1, characterized in that In step (1), the molar ratio of the squaric acid to the solid strong base compound is 1 / 4 to 1 / 1.

4. The method according to claim 2, wherein In step (1), the ball milling time of the ball milling treatment is 5 to 30 min, and the ball milling speed is 100 to 500 r / min.

5. The method according to claim 1, wherein In step (1), the solid strong base compound is one or more of sodium hydroxide and potassium hydroxide; Preferably it is sodium hydroxide.

6. The method according to claim 1, wherein In step (2), the molar ratio of the squarate to calcium sulfate dihydrate contained in the phosphogypsum is 1 / 2 to 2 / 1.

7. The method according to claim 2, wherein In step (2), the ball milling time of the ball milling treatment is 5 to 30 min, and the ball milling speed is 100 to 500 r / min.

8. The method according to claim 1, wherein In step (2), the phosphogypsum is waste phosphogypsum, and the mass percentage content of calcium sulfate dihydrate is preferably above 95 wt%.

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