Preparation method and application of Ca / Mg mineral gel

Abstract

The present invention provides a preparation method and application of a Ca / Mg mineral gel. Under normal temperature and pressure conditions, a MgCl2 solution is first prepared using a vapor diffusion method to obtain a dilute Mg gel solution. CaO powder is then added to the dilute Mg gel solution, and the vapor diffusion method is continued to obtain the Ca / Mg mineral gel. The preparation method of the present invention, which carries out the reaction under normal temperature and pressure conditions, achieves low-cost, large-scale production, overcoming the shortcomings of traditional adsorbents, such as high preparation costs, high energy consumption, complex preparation processes, and difficult handling of adsorbed products. The Ca / Mg mineral gel demonstrates significant advantages in the synergistic removal of N / P organic pollutants and heavy metal pollutants in water, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the field of adsorbent preparation, and in particular to a preparation method and application of a Ca / Mg mineral gel. Background Art

[0002] With the rapid development of the economy and society, water pollution is becoming increasingly serious. Eutrophication and heavy metal pollution caused by elements such as nitrogen (N) and phosphorus (P) in water bodies are particularly concerning. Common water pollution treatment technologies include chemical precipitation, membrane permeation, biological remediation, adsorption, advanced oxidation, and electrolysis. Adsorption uses adsorbents to absorb harmful substances in wastewater (such as organic pollutants such as N, P, and N / P, as well as heavy metal pollutants) to purify the wastewater. Adsorption is widely used due to its low energy consumption, low cost, and ease of recycling.

[0003] Adsorption methods employ a wide variety of adsorbents, including hydrogels, clays, metal-organic frameworks, carbon-based materials, and biomass. These adsorbents typically possess high specific surface area, abundant pore volume, and surface functional groups. However, existing adsorbents are limited by low adsorption capacity, complex synthesis processes, and high costs, hindering their widespread application. Compared to traditional adsorbents, mineral adsorbents offer advantages such as high treatment efficiency and speed. Currently, a variety of mineral adsorbents have been developed for water treatment, including iron-based nanoadsorbents, hollow manganese dioxide structures, multi-walled carbon nanotubes attached to carboxymethyl cellulose, hollow magnesium silicate nanostructures, and mesoporous Fe-Ti hollow microspheres. These adsorbents can adsorb toxic and harmful pollutants in a short period of time and exhibit high adsorption capacity. However, the preparation process for these mineral adsorbents is relatively complex, resulting in high costs, and the products formed after adsorption are difficult to handle, which, to a certain extent, limits their widespread application. Furthermore, most existing mineral adsorbents are crystalline materials, resulting in relatively slow adsorption kinetics. Summary of the Invention

[0004] The present invention aims to provide a preparation method and application of Ca / Mg mineral gel, which makes up for the shortcomings of traditional adsorbents used for water pollution control, such as high preparation cost, high energy consumption, complex preparation process and difficult treatment of adsorbed products.

[0005] To achieve the above objectives, the present invention proposes the following technical solutions:

[0006] A method for preparing a Ca / Mg mineral gel comprises the following steps: firstly, under normal temperature and pressure conditions, using a vapor diffusion method to prepare a dilute Mg gel solution from a MgCl2 solution; then, adding CaO powder to the dilute Mg gel solution, and using a vapor diffusion method to prepare the Ca / Mg mineral gel.

[0007] As a preferred technical solution of the present invention, the following steps are specifically included:

[0008] Step 1: Under normal temperature and pressure conditions, MgCl2 is added to a solvent and ultrasonically mixed to prepare a MgCl2 solution with a concentration of 0.8g / L-10g / L, and then the MgCl2 solution is reacted by a vapor diffusion method for 12h-36h to prepare the Mg dilute gel solution with a concentration of 1.6g / L-1.9g / L; the gas phase used in the vapor diffusion reaction in step 1 is a mixed gas of NH3 and CO2;

[0009] Step 2: At room temperature and pressure, CaO powder is added to the dilute Mg gel solution at a mass ratio of 1:320-1600. Ultrasonic mixing is then performed, followed by a vapor diffusion reaction for 12-36 hours to produce an amorphous Ca / Mg mineral gel with a concentration of 1.9-2.3 g / L. It can be seen that no organic additives or surfactants are required in step 2.

[0010] In the embodiment of the present invention, the order of step 1 and step 2 cannot be changed, that is, the order of adding MgCl2 and CaO powder to the solution cannot be changed, and MgCl2 and CaO powder cannot be added to the solution at the same time, otherwise the mineral gel cannot be synthesized.

[0011] As a preferred technical solution of the present invention, the solvent in step 1 is pure ethanol solution.

[0012] As a preferred technical solution of the present invention, the gas phase in the gas phase diffusion method in step 2 is CO2 gas, or a mixed gas of NH3 and CO2, and the molar ratio of NH3 to CO2 is 1:2-5.

[0013] As a preferred technical solution of the present invention, the water content of the Ca / Mg mineral gel is 90-95%.

[0014] As a preferred technical solution of the present invention, the molar ratio of Ca to Mg in the Ca / Mg mineral gel is Ca:Mg=1:1-3.

[0015] When dry gel is required, the prepared Ca / Mg mineral gel is centrifuged at 5000-7000 rpm for 1-3 min, then washed 2-3 times with anhydrous ethanol solvent, and finally freeze-dried at -50°C to obtain Ca / Mg mineral dry gel. The water content of the Ca / Mg mineral dry gel is 35%.

[0016] The present invention also provides an application of the Ca / Mg mineral gel prepared by the above preparation method, wherein the Ca / Mg mineral gel is used as an adsorbent to adsorb P, N / P, and heavy metal pollutants in water.

[0017] As a preferred technical solution of the present invention, the product generated after the catalyst adsorbs P and N / P pollutants in water can be directly used as fertilizer for crop growth.

[0018] The preparation method of the Ca / Mg mineral gel provided by the technical solution of the present invention has the following advantages over the prior art:

[0019] (1) Except for the ethanol solvent, no organic additives or surfactants are added. The preparation process is carried out at room temperature and pressure, and no high-temperature and high-pressure equipment is required. Therefore, large-scale and low-cost production of the product can be achieved in a relatively short time, thus solving the problems of difficult preparation, high energy consumption, and high cost of traditional adsorbents used for water pollution control.

[0020] (2) The Ca / Mg mineral gel prepared by this method has a three-dimensional cross-linked network amorphous structure at the microscopic level, which allows pollutants in the water to diffuse rapidly and react with it after contact with it. The Ca / Mg mineral gel does not need to be further separated and dried when used, and can be directly used for the efficient removal of various water pollutants such as P, N / P and heavy metals. It has a very broad application prospect in the field of sewage adsorption treatment.

[0021] (3) The Ca / Mg mineral gel prepared by this method has a higher adsorption rate and efficiency than the amorphous magnesium carbonate mineral gel. The reason is that the addition of Ca changes the pH value of the solution, keeping the pH value of the solution at around 6.2, which promotes the formation of struvite.

[0022] (4) When the Ca / Mg mineral gel prepared by this method is used to remove N / P pollutants in water bodies, the products generated are calcium hydrogen phosphate and struvite, which can be directly used as fertilizer for crop growth without causing secondary pollution. Therefore, the adsorption products do not need further treatment.

[0023] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, to the extent such concepts are not mutually inconsistent, can be considered to be part of the inventive subject matter of this disclosure.

[0024] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of the exemplary embodiments, will become apparent from the following description or through practice of specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are not drawn to scale. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0026] Figure 1 This is a transmission electron micrograph of the Ca / Mg mineral gel according to an embodiment of the present invention;

[0027] Figure 2 The specific surface area and pore size analysis of the Ca / Mg mineral gel in the embodiment of the present invention;

[0028] Figure 3 The pseudo first-order kinetic curve and isothermal curve of the Ca / Mg mineral dry glue for removing P in the embodiment of the present invention;

[0029] Figure 4 The pseudo first-order kinetic curve and isothermal curve of the Ca / Mg mineral dry glue for removing N / P in the embodiment of the present invention;

[0030] Figure 5 The pseudo first-order kinetic curve and isotherm curve of the Ca / Mg mineral wet glue for removing N / P in the embodiment of the present invention are shown;

[0031] Figure 6 The Ca / Mg mineral dry glue in the embodiment of the present invention removes heavy metal Cu 2+ 、Co 2+ and Ni 2+ Schematic diagram of . DETAILED DESCRIPTION

[0032] To further clarify the objectives, technical solutions, and advantages of the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments derived by persons of ordinary skill in the art without requiring creative effort are within the scope of protection of the present invention. Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meanings understood by persons of ordinary skill in the field to which the present invention pertains.

[0033] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and similar words do not indicate a quantitative limitation, but rather indicate the presence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" include the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up" and "down" are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0034] An embodiment of the present invention provides a method for preparing a Ca / Mg mineral gel. Under normal temperature and pressure conditions, a MgCl2 solution is first prepared by a vapor diffusion method to obtain a Mg dilute gel solution; then CaO powder is added to the Mg dilute gel solution and a vapor diffusion method is used to prepare the desired Ca / Mg mineral gel.

[0035] The specific steps include:

[0036] Step 1: Under normal temperature and pressure conditions, 0.08g-0.5g MgCl2 crystals are added to 50mL-100mL of solvent and ultrasonically mixed to obtain a MgCl2 solution after the MgCl2 is completely dissolved. The MgCl2 solution is then reacted by vapor diffusion for 12h-24h to prepare a dilute Mg gel solution. The formation of the dilute Mg gel solution is the key to the successful preparation of the Ca / Mg mineral gel. In this embodiment, during the vapor diffusion reaction, a clean, dry, open container is filled with a certain amount of the MgCl solution prepared above. This open container, along with a weighing bottle containing solid ammonium bicarbonate, is then placed in a sealed desiccant. The mouth of the weighing bottle is sealed with a layer of Parafilm film perforated with three small holes (the number of holes can be selected as needed). These holes allow the NH3 and CO2 mixed gas continuously released by the ammonium bicarbonate solid to escape and enter the desiccant. The mixed gas diffuses and contacts and reacts with the MgCl solution in the desiccant. After 12-24 hours of reaction, a dilute Mg gel solution is produced. Simultaneously, a certain amount of a desiccant, such as color-changing silica gel, is placed in another open container within the desiccant to absorb moisture from the air inside the desiccant, reduce humidity, eliminate interference from moisture in the air, and prevent the formation of the dilute Mg gel solution.

[0037] Step 2: Under normal temperature and pressure conditions, 0.05g-0.1g CaO powder is added to 50mL-100mL of the Mg dilute gel solution prepared in step 1, and the mixture is ultrasonically mixed. Then, the above-mentioned Mg dilute gel solution mixed with CaO powder is reacted by vapor diffusion method for 12h-24h to prepare an amorphous Ca / Mg mineral gel. In this embodiment, during the vapor diffusion reaction, a clean, dry, open container was filled with a certain amount of the dilute Mg-CaO-mixed gel solution prepared above. This open container, along with a weighing bottle containing solid ammonium bicarbonate, was then placed in a sealed desiccator. The mouth of the weighing bottle was sealed with a layer of Parafilm film punctured with three small holes (the number of holes can be selected based on actual needs). The holes allowed the NH3 and CO2 mixed gas released by the ammonium bicarbonate solid to escape and enter the desiccator. The ammonium bicarbonate solid continuously released NH3 and CO2 gases, which diffused and reacted with the dilute Mg-CaO-mixed gel solution in the desiccator. After 12-24 hours of reaction, the Ca / Mg mineral gel was produced. Simultaneously, a certain amount of concentrated sulfuric acid was placed in another open container inside the desiccator to absorb moisture from the air inside the desiccator, reducing humidity and eliminating moisture interference. Furthermore, the sulfuric acid also absorbed excess NH3 gas to prevent it from interfering with the formation of the Ca / Mg mineral gel.

[0038] Step 3: Centrifuge the Ca / Mg mineral gel at 5000-7000 rpm for 1-3 minutes, then wash three times with ethanol and freeze-dry at -50°C to produce a Ca / Mg mineral gel with a water content of 35%. The resulting Ca / Mg mineral gel can be stored for extended periods and can be directly added to the water to be purified. If the Ca / Mg mineral gel is to be used immediately or shortly after production, step 3 is not necessary and the gel can be used directly as a wet gel without separation or drying, making it convenient to use.

[0039] In this embodiment, the solvent in step 1 is pure ethanol solution, and the relative density of pure ethanol solution is 0.7893 g / cm 3 .

[0040] In this embodiment, the gas phase in the gas phase diffusion method in step 1 is a mixed gas of NH3 and CO2, and the mixed gas of NH3 and CO2 is released by ammonium bicarbonate solid, or by other substances, devices or equipment that can release NH3 and CO2 gases.

[0041] In this embodiment, the gas phase in the gas diffusion method in step 2 is pure CO2 gas, and the CO2 gas is released by a substance, device or equipment that can release CO2 gas; or the gas phase is a mixed gas of NH3 and CO2, and the mixed gas of NH3 and CO2 is released by ammonium bicarbonate solid, or by other substances, devices or equipment that can release NH3 and CO2 gases. The preferred ratio of the NH3 and CO2 mixed gas is 1:2-5.

[0042] In this embodiment, the water content of the Ca / Mg mineral gel is 90%-95%, and has excellent adsorption capacity.

[0043] In this embodiment, the molar ratio of Ca to Mg in the Ca / Mg mineral gel is Ca:Mg = 1:1-3. By adjusting the amount of Ca and Mg added, Ca / Mg mineral gel systems with different Ca / Mg molar ratios can be prepared. The preferred concentration of MgCl2 dissolved in pure ethanol solvent is 0.8g / L-10g / L. The preferred mass ratio of CaO powder to the dilute Mg gel solution is 1 / 1600-1 / 320.

[0044] An embodiment of the present invention further provides an application of the Ca / Mg mineral gel prepared by the above preparation method, wherein the Ca / Mg mineral gel is used as an adsorbent to adsorb P, N / P, and heavy metal pollutants in water.

[0045] Mineral adsorbents (such as phosphates, carbonates, and silicates) are abundant in natural resources, inexpensive, and easily mass-produced, making them highly suitable for practical application. Amorphous mineral gels, in particular, possess three-dimensional nanoporous network structures, low density, high specific surface area, and large porosity. Compared to crystalline materials, they exhibit superior adsorption performance and adsorption kinetics. In summary, amorphous mineral adsorbents offer advantages over other adsorbents in terms of cost, adsorption efficiency, and product processing, and possess broad development potential.

[0046] The Ca / Mg mineral gel prepared in the embodiment of the present invention has a higher adsorption speed and efficiency than pure amorphous calcium carbonate or magnesium carbonate mineral gel. The reason is that the addition of the Ca component has an advantage in increasing the pH of the solution, which can make the pH of the solution greater than 6.2, reaching a pH range that is conducive to the formation of struvite, so that the adsorption reaction has a tendency to proceed in the direction of generating struvite products, thereby improving the adsorption effect; when the Ca / Mg mineral gel prepared by this method is used to adsorb and remove N / P pollutants in water bodies, the adsorption products are calcium hydrogen phosphate and struvite, which can be directly used as fertilizer for crop growth without generating secondary pollution. Therefore, the adsorption product does not require further treatment and is very suitable for promotion and application.

[0047] Example 1

[0048] Step 1: Under normal temperature and pressure conditions, 0.095g of MgCl2 crystals are dissolved in 50mL-100mL of pure ethanol solution, ultrasonically mixed, and MgCl2 is completely dissolved to obtain a MgCl2 solution, which is then reacted by a vapor diffusion method to prepare a dilute Mg gel solution. In this embodiment, an open container is used to store a certain amount of the MgCl2 solution prepared above. Then, the open container and a weighing bottle containing ammonium bicarbonate solid (which can release NH3 and CO2 gas) are placed in a sealed desiccator. The bottle mouth of the weighing bottle is sealed and covered with a layer of Parafilm film, and three small holes are pierced in the film to allow the NH3 and CO2 mixed gas released by the ammonium bicarbonate solid to escape and enter the desiccator. The ammonium bicarbonate solid continuously releases NH3 and CO2 gas, wherein the ratio of NH3 to CO2 gas is (<1:1). The mixed gas diffuses and contacts the MgCl2 solution in the desiccator to react. After 12 hours of reaction, the dilute Mg gel solution is obtained. In addition, a certain amount of desiccant such as color-changing silica gel is placed in another open container inside the dryer to reduce the air humidity inside the dryer.

[0049] Step 2: Under normal temperature and pressure conditions, 0.056g of CaO powder is added to the above-mentioned Mg dilute gel solution, ultrasonically mixed, and then the Mg dilute gel solution mixed with CaO powder is reacted by vapor diffusion to prepare a Ca / Mg mineral gel. In this embodiment, during the vapor diffusion reaction, an open container is used to store a certain amount of the above-prepared Mg dilute gel solution mixed with CaO. Then, the open container and a weighing bottle containing ammonium bicarbonate solid are placed in a sealed desiccant, wherein the bottle mouth of the weighing bottle is sealed with a layer of Parafilm film, and three small holes are pierced in the film to allow the NH3 and CO2 mixed gas released by the ammonium bicarbonate solid to escape and enter the desiccant. The ammonium bicarbonate solid continuously releases NH3 and CO2 gas, wherein the ratio of NH3 to CO2 gas is (1:2-5). The mixed gas diffuses and contacts and reacts with the Mg dilute gel solution mixed with CaO in the desiccant; after reacting for 12 hours, the Ca / Mg mineral gel is obtained. In addition, a certain amount of desiccant such as color-changing silica gel is placed in another open container inside the dryer to reduce the air humidity inside the dryer.

[0050] Step 3: centrifuge the Ca / Mg mineral gel at 6000 rpm for 2 minutes, wash it with anhydrous ethanol solvent for 3 times, and finally freeze-dry it at -50°C to obtain Ca / Mg mineral dry gel. The water content of the Ca / Mg mineral dry gel is 35%.

[0051] In the embodiment of the present invention, by adjusting the ratio of CaO and MgCl2, Ca / Mg mineral gels with Ca / Mg molar ratios of 0.7:1, 0.4:1, and 0.34:1 can be prepared. When step 2 is omitted, pure Mg mineral gel can be obtained.

[0052] Furthermore, when the molar ratio of the raw materials CaO and MgCl2 is 1:2, the molar ratio of Ca / Mg in the mineral dry glue is 0.4:1=1:2.5. At this time, the adsorption capacity of Ca / Mg mineral dry glue on N / P is the highest; when the molar ratio of the raw materials CaO and MgCl2 is 0:1, it means that the mineral dry glue does not contain Ca and is pure Mg mineral dry glue, and the adsorption capacity of pure Mg mineral dry glue is relatively small.

[0053] Table 1 Specific surface area, average pore size and maximum adsorption capacity of Ca / Mg mineral dry colloids with different molar ratios

[0054]

[0055] like Figure 2 The figure shows the specific surface area and pore size analysis of the Ca / Mg mineral gel. It can be seen that the N2 isotherm of the Ca / Mg mineral gel shows moderate adsorption. According to the latest IUPAC classification, the mesopores can be classified as type III. The isotherm in the relative high pressure range of 0.4–1.0 shows a typical H3 type hysteresis loop isotherm. The Ca / Mg mineral gel exhibits typical mesopores with a diameter of about 11.07 nm and a BET specific surface area of ​​about 47.62 m 2 g -1 The high BET surface area, rich pores and network structure of the mineral gel are beneficial to the adsorption, diffusion and exchange of ions.

[0056] Experimental Example 1

[0057] Prepare a standard pollutant sample by dissolving 0.007 mol potassium dihydrogen phosphate in 200 mL of water. Add 0.5 g of dry Ca / Mg mineral glue (Ca / Mg = 0.4:1) and measure the PO4 content of the solution at different times using a total phosphorus detector. 3- content, draw the adsorption kinetics curve ( Figure 3 The Langmuir and Freundlich isotherm models were used to fit the process of potassium dihydrogen phosphate adsorption on Ca / Mg mineral gel samples ( Figure 3 ), the results show that the fitting results are more consistent with the Langmuir isotherm adsorption model, indicating that the pollutants are first adsorbed on the adsorbent surface and then react with the adsorbent. After calculation, the maximum adsorption capacity of the adsorbent for P is q max (P) = 100 mg / g.

[0058] The specific reaction process is as follows:

[0059] KH2PO4+(Ca / Mg)CO3·nH2O→CaHPO4↓+Mg3(PO4)2↓

[0060] Experimental Example 2

[0061] Prepare a standard pollutant sample by dissolving 0.007 mol of ammonium dihydrogen phosphate in 200 mL of water. Add 0.5 g of dry Ca / Mg mineral glue (Ca / Mg = 0.4:1) and measure the PO4 content of the solution at different times using a total phosphorus detector. 3- content, draw the adsorption kinetics curve ( Figure 4 ), and found that the adsorption amount of N / P in this adsorption experiment was higher than that of P alone. The Langmuir and Freundlich isotherm models were used to fit the process of sample adsorption of ammonium dihydrogen phosphate ( Figure 4 ), the fitting results are more consistent with the Langmuir isotherm adsorption model, indicating that the adsorbate adsorbed on the adsorbent surface is evenly distributed, there is no interaction between the adsorbates and it is a single-layer positioning adsorption, and the adsorption reaction only occurs on the outer surface of the adsorbent. After calculation, the maximum adsorption capacity of the adsorbent for P is q max (P) = 196 mg / g, the maximum adsorption capacity for N is q max (N) = 80.7 mg / g.

[0062] The specific reaction process is as follows:

[0063] NH4H2PO4+(Ca / Mg)CO3·nH2O→CaHPO4↓+MgNH4PO4↓

[0064] Experimental Example 3

[0065] Prepare a standard pollutant sample by dissolving 0.007 mol of ammonium dihydrogen phosphate in 200 mL of water. Add 7.73 g of Ca / Mg mineral wet gel (Ca / Mg = 0.4:1) and measure the PO4 content of the solution at different times using a total phosphorus detector. 3- content, draw the adsorption kinetics curve ( Figure 5 ), and found that the adsorption amount of N / P in this adsorption experiment was higher than that of P alone. The Langmuir and Freundlich isotherm models were used to fit the process of sample adsorption of ammonium dihydrogen phosphate ( Figure 5 ), the fitting results are more consistent with the Langmuir isotherm adsorption model, indicating that the adsorbate is evenly distributed on the adsorbent surface, there is no interaction between the adsorbates and it is a single-layer positioning adsorption, and the adsorption reaction only occurs on the outer surface of the adsorbent. After calculation, the maximum adsorption capacity of the adsorbent for P is q max(P) = 244 mg / g, the maximum adsorption capacity for N is q max (N) = 112 mg / g.

[0066] From Experimental Examples 1 and 2, it can be seen that compared with the adsorption removal of P(q max (P) = 100 mg / g), the Ca / Mg mineral dry glue is more efficient in removing N / P (q max (P) = 196 mg / g, q max (N) = 80.7 mg / g). It can be seen from Experimental Examples 2 and 3 that the adsorption rate is higher when wet glue is used to remove N / P than when dry glue is used (q max (P)=244mg / g,q max (N) = 112 mg / g).

[0067] Experimental Example 4

[0068] like Figure 6 As shown, 9600mM copper chloride, 10600mM cobalt chloride, and 5800mM nickel chloride solutions were respectively prepared as simulated heavy metal pollutants, and Ca / Mg mineral gel adsorbents with a Ca / Mg molar ratio of 0.4:1 were added thereto. After 2 minutes of sufficient adsorption and reaction, the non-ferrous metals were rapidly precipitated, and the ion concentrations in the remaining liquid were measured to be 0.122mM, 0.042mM, and 0.217mM, respectively. The above shows that the Ca / Mg mineral gel prepared in the embodiment of the present invention has a significant effect on the adsorption of heavy metals in water, and has great advantages over other adsorbents.

[0069] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A method for preparing a Ca / Mg mineral gel, characterized in that: Under normal temperature and pressure conditions, the MgCl2 solution is first placed in a mixed gas atmosphere containing NH3 and CO2 gases, and a Mg dilute gel solution is prepared by a gas phase diffusion method; then CaO powder is added to the Mg dilute gel solution, and the solution is placed in an atmosphere containing CO2 gas, or a mixed gas atmosphere of NH3 and CO2 gases, and a Ca / Mg mineral gel is prepared by a gas phase diffusion method.

2. The method for preparing the Ca / Mg mineral gel according to claim 1, wherein The steps include: Step 1: Under normal temperature and pressure conditions, MgCl2 is added to a solvent and ultrasonically mixed to prepare a MgCl2 solution with a concentration of 0.8 g / L-10 g / L, and then the MgCl2 solution is reacted by a vapor diffusion method for 12 h-24 h to prepare the Mg dilute gel solution with a concentration of 1.6 g / L-1.9 g / L; Step 2: Under normal temperature and pressure conditions, CaO powder is added to the Mg dilute gel solution, the mass ratio of the CaO powder to the Mg dilute gel solution is 1:320-1600, ultrasonic mixing is carried out, and then the reaction is carried out for 12h-24h by vapor diffusion method to obtain an amorphous Ca / Mg mineral gel with a concentration of 1.9g / L-2.3g / L.

3. The method for preparing the Ca / Mg mineral gel according to claim 2, wherein: The solvent in the step 1 is pure ethanol solution.

4. The method for preparing the Ca / Mg mineral gel according to claim 2, wherein: The gas phase in the gas phase diffusion method in step 2 is CO2 gas, or a mixed gas of NH3 and CO2, and the molar ratio of NH3 to CO2 is 1:2-5.

5. The method for preparing the Ca / Mg mineral gel according to any one of claims 1 to 4, characterized in that: The water content of the Ca / Mg mineral gel is 90%-95%.

6. The method for preparing the Ca / Mg mineral gel according to any one of claim 5, characterized in that: The molar ratio of Ca to Mg in the Ca / Mg mineral gel is Ca:Mg=1:1-3.

7. An application of the Ca / Mg mineral gel prepared by the method for preparing the Ca / Mg mineral gel according to any one of claims 1 to 6, characterized in that: The Ca / Mg mineral gel is used as an adsorbent to adsorb P, N / P and heavy metal pollutants in water.

8. Use of the Ca / Mg mineral gel prepared by the method for preparing the Ca / Mg mineral gel according to claim 7, characterized in that: The product generated by the Ca / Mg mineral gel after adsorbing P and N / P pollutants in water can be directly used as fertilizer for crop growth.

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