Preparation method of hydroxyl phosphorus ferric sulfate confinement material

Abstract

The invention belongs to the technical field of composite material preparation, and particularly relates to a preparation method of a hydroxyl phosphorus ferric sulfate confinement material, which comprises the following steps: (1) mixing a ferrite solution with a phosphoric acid compound, adding sulfuric acid to adjust the pH value, adding an oxidizing agent to oxidize, preserving heat and curing to obtain a precursor solution; and (2) impregnating the carrier in the precursor solution, primarily washing the impregnated carrier, adding the impregnated carrier into alkali liquor, precipitating, washing again, and drying to obtain the hydroxyl phosphorus ferric sulfate confinement material. Fresh ferric ions are obtained through ferrous oxide ions, the performance stability of the hydroxyl phosphorus ferric sulfate confinement material is enhanced, and the environment purification capacity of the hydroxyl phosphorus ferric sulfate confinement material is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material preparation, and particularly relates to a preparation method of a hydroxyapatite sulfate iron confined material. Background Art

[0002] Hydrated iron oxide is a compound containing crystal water. Its iron-based oxide can catalyze oxidants to produce active substances to decompose organic ligands. Moreover, hydrated iron oxide has a high specific surface area, porosity, and abundant hydroxyl functional groups, which are convenient for adsorbing heavy metal ions after oxidation decomposition. However, hydrated iron oxide is prone to agglomeration and inactivation during the preparation and application processes, and the operation and reuse are difficult, resulting in the difficulty of applying hydrated iron oxide to the treatment of actual industrial wastewater. By using the nano-confined structure in the framework carrier to encapsulate functional nanoparticles, the material can maintain its nano-size and functionality during the preparation and application processes, enhancing the environmental purification performance of the material.

[0003] Most of the existing preparation processes of hydrated iron oxide confined materials adopt the impregnation-precipitation method, and the impregnation solution is an iron ion solution. The process is described in detail in the literature "Enhanced removal of tris(2-chloroethyl) phosphate using a resin-based nanocomposite hydrated iron oxide through a Fenton-like process: Capacity evaluation and pathways. Water Research. 2020. 175(5): 115655.". The precursor is an iron poly-mer that undergoes disordered hydrolysis and polymerization, and it is difficult to control the charge on the surface of the iron poly-mer particles, which affects the performance stability of this kind of material and makes it difficult to be popularized and applied.

[0004] Chinese Patent CN108579682A discloses a hydroxyiron-modified cationic resin composite material and its preparation method and application. The method is as follows: (1) Treat the cationic resin with an acid to obtain a pretreated resin; the cationic resin is a strongly acidic cationic resin; (2) Dissolve iron citrate FeC 6 H 5 O 7 in an ethanol aqueous solution to obtain an FeC 6 H 5 O 7 mixed solution; mix the pretreated resin with FeC 6 H 5 O 7Mix the mixed solution, adjust the pH, stir and react, age, and perform subsequent treatment to obtain a hydroxyl iron-modified cationic resin composite material. This patent does not optimize the regulation of the iron aggregates as the hydroxyl iron precursor in the iron citrate ethanol aqueous solution. It can be seen from the SEM images that the surface pores of the macroporous cationic resin as the carrier have been blocked, which will significantly reduce the specific surface area of the product and affect the environmental purification ability of the product. Summary of the Invention

[0005] Based on the deficiencies in the above prior art, the technical problem to be solved by the present invention is: to provide a preparation method of a hydroxyl phosphosulfate iron confinement material, to solve the problem that the precursor is difficult to control and affects the performance stability of the sample, and the performance stability and environmental purification ability of the prepared hydroxyl phosphosulfate iron confinement material are improved.

[0006] The technical solution adopted by the present invention to solve its technical problems is: The preparation method of the hydroxyl phosphosulfate iron confinement material according to the present invention is characterized by including the following steps: (1) Mix the ferrous salt solution with the phosphoric acid compound, add sulfuric acid to adjust the pH value, then add an oxidant for oxidation and keep warm for ripening to obtain a precursor solution; (2) Immerse the carrier in the precursor solution, perform preliminary washing on the impregnated carrier, then add the impregnated carrier to an alkali solution for precipitation, wash and dry again to obtain a hydroxyl phosphosulfate iron confinement material.

[0007] Wherein: In the step (1), the oxidant is hydrogen peroxide or sodium hypochlorite, the concentration of the ferrous salt solution is 1-2 mol / L, and the ferrous salt in the ferrous salt solution is ferrous sulfate heptahydrate.

[0008] In the step (1), the pH value is 1.1-2.8, and the molar ratio of the oxidant to the ferrous salt in the ferrous salt solution is 0.04-0.06.

[0009] In the step (1), the phosphoric acid compound is one of Na 3 PO 4 、NaH 2 PO 4 or H 3 PO 4 , and the molar ratio of the phosphoric acid compound to the ferrous salt in the ferrous salt solution is 0.075-0.15.

[0010] In the step (1), the oxidation temperature is 30-35 °C, the oxidation time is 0.5-1 h, the heat preservation temperature is 50-80 °C, and the heat preservation time is 1-8 h.

[0011] In the step (2), the carrier is D001 cation exchange resin, the impregnation time is 6 - 24 h, and during the impregnation process, oscillation stirring is carried out, and the stirring speed is 100 - 300 rpm; The preparation method of D001 cation exchange resin is as follows: Measure 30 mL of wet D001 microspheres, load them into the exchanger, and wash the resin with clear water until the effluent is clear; first, introduce 1 mol / L NaOH with a volume twice that of the resin into the exchanger and soak for 1 - 2 h, then wash with clear water until the pH is 9 - 10; then soak with 1 mol / L HCl with a volume twice that of the resin for 1 - 2 h, and wash with clear water until the pH is 3 - 5, and then transfer the pretreated ion exchange resin to a vacuum drying oven and dry it for 5 h under vacuum to obtain D001 cation exchange resin.

[0012] In the step (2), the mass ratio of the carrier to the precursor solution is 1:28 - 32, and the preliminary washing is to wash with deionized water until the water is colorless.

[0013] In the step (2), the lye is NaOH solution, the concentration of the lye is 0.1 - 1 mol / L, the mass ratio of the impregnated carrier to the lye is 1:28 - 32, and the precipitation time is 10 - 24 h.

[0014] In the step (2), the re - washing is to wash with deionized water until neutral.

[0015] In the step (2), the drying temperature is 50 - 80 °C, and the drying time is 5 - 10 h.

[0016] In the present invention, by combining ferrous salt with phosphate ions and introducing sulfate ions under acidic conditions, it is possible to prevent the formation of colloidal solutions during the conversion of ferrous ions into ferric ions and reduce the activity of ferric ions. When oxidized by an oxidant, phosphate ions and sulfate ions first combine with ferric ions, enabling ferric ions to be in a free state in the solution. The free - state iron ions continuously polymerize to form aggregates, obtaining a precursor solution with high ionic activity. Adding cation exchange resin as a carrier to the precursor solution can better adsorb ferric ions on the surface of the cation exchange resin. Adding lye during the adsorption process can introduce OH - to make the combination process of ferric ions and cation exchange resin more stable, and obtain a hydroxyphosphosulfate - iron confined material.

[0017] The beneficial effects of the present invention are: The present invention obtains fresh ferric ions by oxidizing ferrous ions, and then by controlling polymerization conditions such as temperature and pH value, and introducing PO that can compete with OH - for the bridging effect between Fe 3+ and having an inter - bridging effect 43- and SO 4 2- ,PO 4 3- 、SO 4 2- and OH - all contain oxygen atoms that can coordinate with Fe 3+ However, PO 4 3- and SO 4 2- are larger in volume than OH - and they carry more negative charges than OH - , and their spatial structures are more suitable for binding multiple Fe 3+ ; PO 4 3- binds to Fe 3+ with a slightly weaker strength than OH - but stronger than SO 4 2- When SO 4 2- is used alone, its competitiveness with OH - is insufficient, while when PO 4 3- is used alone, its competitiveness with OH - is too strong, which will also cause the risk of Fe 3+ to become ferric phosphate precipitate. Therefore, it is necessary for PO 4 3- and SO 4 2- to form aggregates synergistically continuously, thereby realizing the regulation of the particle size and surface charge of the aggregates as precursors in the precursor solution, enabling the aggregates to maintain a small particle size and abundant surface active sites, enhancing the performance stability of the hydroxyphosphate sulfate iron confined material. When purifying water, the active sites on the surface of the hydroxyphosphate sulfate iron confined material play a role, which can improve the environmental purification ability of the hydroxyphosphate sulfate iron confined material. Description of the Drawings

[0018] Figure 1 is a schematic diagram of the variation relationship between the particle size of the precursor and PO 4 3- / Fe 2+ ; among them, A is the schematic diagram of the variation relationship between the particle size of the precursor and PO 4 3- / Fe 2+ when it is 0 - 0.05, and B is the schematic diagram of the variation relationship between the particle size of the precursor and PO 4 3- / Fe 2+ when it is 0.075 - 0.125; Figure 2 The Zeta potential of the precursor varies with PO 4 3- / Fe 2+ Schematic diagram of the variation relationship; Figure 3 SEM test result diagram of the hydroxyapatite ferric sulfate confined material prepared in Example 2 at 10 μm; Figure 4 SEM test result diagram of the hydroxyapatite ferric sulfate confined material prepared in Example 2 at 2 μm; Figure 5 EDS test result diagram of O in the hydroxyapatite ferric sulfate confined material prepared in Example 2 at 2 μm; Figure 6 EDS test result diagram of P in the hydroxyapatite ferric sulfate confined material prepared in Example 2 at 2 μm; Figure 7 EDS test result diagram of Fe in the hydroxyapatite ferric sulfate confined material prepared in Example 2 at 2 μm; Figure 8 SEM test result diagram of the hydroxyapatite ferric sulfate confined material after treating methylene blue in Example 2 at 2 μm; Figure 9 EDS test result diagram of the hydroxyapatite ferric sulfate confined material after treating methylene blue in Example 2 at 2 μm; Figure 10 SEM test result diagram of the hydroxyapatite ferric sulfate confined material after adsorbing copper ions in Example 2 at 2 μm; Figure 11 EDS test result diagram of the hydroxyapatite ferric sulfate confined material after adsorbing copper ions in Example 2 at 2 μm. Detailed implementation manners

[0019] The present invention will be further illustrated by the following examples.

[0020] Prepare PO 4 3- / Fe 2+ Solutions with different proportion gradients: Dissolve 0.05 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add 0.0075 mol of sulfuric acid, prepare six groups of the same solution, and add trisodium phosphate to the six groups of solutions according to the molar ratios of trisodium phosphate to ferrous sulfate heptahydrate of 0, 0.025, 0.05, 0.075, 0.1, and 0.125 respectively. After stirring evenly, slowly add 0.0375 mol of hydrogen peroxide for oxidation at 30 °C, and then cure at 50 °C for 4 h to obtain the precursor solution. Subsequently, use a nanoparticle size analyzer to measure the particle size and zeta potential of the precursor. The measurement results are shown in Figure 1-2, The results show that by regulating the molar ratio of phosphate to ferrous ions, the particle size and zeta potential of the precursor can be controlled, thereby affecting the performance of the final sample.

[0021] Example 1 The preparation method of D001 cation exchange resin is as follows: Measure 30 mL of wet D001 microspheres, load them into the exchanger, and wash the resin with clear water until the effluent is clear; first, pass twice the resin volume of 1 mol / L NaOH into the exchanger and soak for 1 h, then wash with clear water until the pH is 9; then soak with twice the resin volume of 1 mol / L HCl for 1 h, and wash with clear water until the pH is 3. Transfer the pretreated ion exchange resin to a vacuum drying oven and dry it under vacuum for 5 h to obtain D001 cation exchange resin; this D001 cation exchange resin is used in Examples 2-10.

[0022] The preparation method of the hydroxyphosphate sulfate iron confined material includes the following steps: (1) Dissolve 0.05 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to the molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.125, then add 0.015 mol of sulfuric acid, with a pH value of 1.8. Slowly add 6 ml of hydrogen peroxide at 30 °C and oxidize for 30 min, then ripen at 50 °C for 4 h to obtain a precursor solution; (2) Immerse 1.67 g of D001 cation exchange resin in 46.76 g of the precursor solution, shake on a shaker at 200 rpm for 24 h, then wash with deionized water until the water is colorless. Subsequently, add the impregnated D001 cation exchange resin to 50 mL of a 1 mol / L NaOH solution and continue to shake and precipitate for 24 h. Finally, wash with deionized water until neutral, then transfer to a vacuum drying oven and dry at 50 °C under a nitrogen atmosphere for 5 h to obtain the hydroxyphosphate sulfate iron confined material.

[0023] Application of the prepared hydroxyphosphate sulfate iron confined material: Take 0.2 g of the hydroxyphosphate sulfate iron confined material and place it in 50 ml of a 50 mg / L methylene blue solution. Adjust the pH value of the methylene blue solution to 3, then add 0.4 mol of hydrogen peroxide, control the temperature at 35 °C, and shake on a shaker at 200 rpm for 1 h to remove methylene blue. After detection, the methylene blue removal rate is 97.88%.

[0024] Take 0.1 g of the hydroxyphosphate sulfate iron confined material and place it in 50 ml of a 50 mg / L copper nitrate solution. Adjust the pH value of the copper nitrate solution to 5, control the temperature at 35 °C, and shake on a shaker at 200 rpm for 90 min to remove copper ions. After detection, the copper ion removal rate is 99.1%.

[0025] Example 2 Preparation method of hydroxyphosphate iron sulfate confined material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.02 mol of sulfuric acid. At this time, the pH value is 1.1. Slowly add 6 ml of hydrogen peroxide dropwise at 30 °C for oxidation for 30 min, and then cure at 50 °C for 4 h to obtain a precursor solution; (2) Immerse 1.67 g of D001 cation exchange resin in 46.76 g of the precursor solution, shake on a shaker at a speed of 200 rpm for 24 h, wash with deionized water until the water is colorless, then add the impregnated D001 cation exchange resin to 50 mL of a NaOH solution with a concentration of 1 mol / L and continue to shake and precipitate for 10 h. Finally, wash with deionized water until neutral, and then transfer to a vacuum drying oven and dry at 50 °C for 5 h in a nitrogen atmosphere to obtain the hydroxyphosphate iron sulfate confined material.

[0026] Application of the prepared hydroxyphosphate iron sulfate confined material: Take 0.2 g of the hydroxyphosphate iron sulfate confined material and place it in 50 ml of a 50 mg / L methylene blue solution. Adjust the pH value of the methylene blue solution to 3, then add 0.4 mol of hydrogen peroxide, control the temperature at 35 °C, and shake on a shaker at 200 rpm for 1 h to remove methylene blue. After detection, the removal rate of methylene blue is 99.22%.

[0027] Take 0.1 g of the hydroxyphosphate iron sulfate confined material and place it in 50 ml of a 50 mg / L copper nitrate solution. Adjust the pH value of the copper nitrate solution to 5, control the temperature at 35 °C, and shake on a shaker at 200 rpm for 90 min to remove copper ions. After detection, the removal rate of copper ions is 99.51%.

[0028] The test result diagram of the prepared hydroxyphosphate iron sulfate confined material and the test result diagrams after treating different solutions are as Figure 3-11 shown.

[0029] Example 3 Preparation method of hydroxyphosphate iron sulfate confined material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.075, then add 0.015 mol of sulfuric acid. At this time, the pH value is 1.8. Slowly add 6 ml of hydrogen peroxide dropwise at 30 °C for oxidation for 30 min, and then cure at 50 °C for 4 h to obtain a precursor solution; (2) Immerse 1.67 g of D001 cation exchange resin in 50.1 g of the precursor solution, shake it on a shaker at 200 rpm for 24 h, then wash it with deionized water until the water is colorless. Subsequently, add the impregnated D001 cation exchange resin to 50 mL of a NaOH solution with a concentration of 0.75 mol / L and continue to shake and precipitate for 12 h. Finally, wash it with deionized water until it is neutral, and then transfer it to a vacuum drying oven and dry it at 60 °C for 8 h under a nitrogen atmosphere to obtain the hydroxyphosphate sulfate iron confined material.

[0030] Application of the prepared hydroxyphosphate sulfate iron confined material: Take 0.2 g of the hydroxyphosphate sulfate iron confined material and place it in 50 ml of a 50 mg / L methylene blue solution. Adjust the pH value of the methylene blue solution to 3, then add 0.4 mol of hydrogen peroxide, control the temperature at 35 °C, and shake it in a water bath oscillator at 200 rpm for 1 h to remove methylene blue. After detection, the removal rate of methylene blue is 99.76%.

[0031] Example 4 Preparation method of the hydroxyphosphate sulfate iron confined material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.15, and then add 0.01 mol of sulfuric acid. At this time, the pH value is 2.8. Slowly add 6 ml of hydrogen peroxide dropwise at 30 °C for oxidation for 30 min, and then cure it at 50 °C for 4 h to obtain the precursor solution; (2) Immerse 1.67 g of D001 cation exchange resin in 50.1 g of the precursor solution, shake it on a shaker at 200 rpm for 24 h, then wash it with deionized water until the water is colorless. Subsequently, add the impregnated D001 cation exchange resin to 50 mL of a NaOH solution with a concentration of 0.375 mol / L and continue to shake and precipitate for 24 h. Finally, wash it with deionized water until it is neutral, and then transfer it to a vacuum drying oven and dry it at 80 °C for 10 h under a nitrogen atmosphere to obtain the hydroxyphosphate sulfate iron confined material.

[0032] Application of the prepared hydroxyphosphate sulfate iron confined material: Take 0.1 g of the hydroxyphosphate sulfate iron confined material and place it in 50 ml of a 50 mg / L copper nitrate solution. Adjust the pH value of the copper nitrate solution to 5, control the temperature at 35 °C, and shake it in a water bath oscillator at 200 rpm for 1.5 h to remove copper ions. After detection, the removal rate of copper ions is 99.9%.

[0033] Example 5 Preparation method of the hydroxyphosphate sulfate iron confined material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.015 mol of sulfuric acid, with a pH value of 1.8. Slowly add 6 ml of hydrogen peroxide dropwise at 30 °C for oxidation for 30 min, and then cure at 50 °C for 4 h to obtain a precursor solution; (2) Immerse 1.67 g of D001 cation exchange resin in 53.44 g of the precursor solution, shake it on a shaker at a speed of 200 rpm for 24 h, then wash it with deionized water until the water is colorless. Subsequently, add the impregnated D001 cation exchange resin to 50 mL of a NaOH solution with a concentration of 0.1 mol / L and continue to shake and precipitate for 24 h. Finally, wash it with deionized water until it is neutral, and then transfer it to a vacuum drying oven and dry it at 70 °C for 6 h under a nitrogen atmosphere to obtain a hydroxyphosphate sulfate iron confinement material.

[0034] Application of the prepared hydroxyphosphate sulfate iron confinement material: Take 0.2 g of the hydroxyphosphate sulfate iron confinement material and place it in 50 ml of a 50 mg / L methylene blue solution. Adjust the pH value of the methylene blue solution to 3, then add 0.4 mol of hydrogen peroxide, control the temperature at 35 °C, and shake it in a water bath oscillator at 200 rpm for 1 h to remove methylene blue. After detection, the methylene blue removal rate reaches 99.76%.

[0035] Example 6 Preparation method of the hydroxyphosphate sulfate iron confinement material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.15, then add 0.01 mol of sulfuric acid, with a pH value of 2.8. Slowly add 6 ml of hydrogen peroxide dropwise at 30 °C for oxidation for 30 min, and then cure at 50 °C for 4 h to obtain a precursor solution; (2) Immerse 1.67 g of D001 cation exchange resin in 53.44 g of the precursor solution, shake it on a shaker at a speed of 200 rpm for 24 h, then wash it with deionized water until the water is colorless. Subsequently, add the impregnated D001 cation exchange resin to 50 mL of a NaOH solution with a concentration of 0.25 mol / L and continue to shake and precipitate for 24 h. Finally, wash it with deionized water until it is neutral, and then transfer it to a vacuum drying oven and dry it at 50 °C for 5 h under a nitrogen atmosphere to obtain a hydroxyphosphate sulfate iron confinement material.

[0036] Application of the prepared hydroxyphosphate sulfate iron confinement material: Take 0.1 g of the hydroxyapatite-sulfate iron-confined material and place it in 50 ml of a 50 mg / L copper nitrate solution. Adjust the pH value of the copper nitrate solution to 5, control the temperature at 35°C, and shake it in a water bath oscillator at 200 rpm for 1.5 h to remove copper ions. After detection, the copper ion removal rate is 99.9%.

[0037] Example 7 A preparation method of the hydroxyapatite-sulfate iron-confined material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.0125 mol of sulfuric acid, with a pH value of 2.3. Slowly add 6 ml of hydrogen peroxide dropwise at 35°C for oxidation for 30 min, and then ripen at 50°C for 4 h to obtain a precursor solution; (2) Immerse 1.67 g of D001 cation exchange resin in 50.1 g of the precursor solution, shake it on a shaker at a speed of 200 rpm for 24 h, wash it with deionized water until the water is colorless, then add the impregnated D001 cation exchange resin to 50 mL of a 0.25 mol / L NaOH solution and continue to shake and precipitate for 24 h. Finally, wash it with deionized water until neutral, and then transfer it to a vacuum drying oven and dry it at 50°C for 5 h under a nitrogen atmosphere to obtain the hydroxyapatite-sulfate iron-confined material.

[0038] Application of the prepared hydroxyapatite-sulfate iron-confined material: Take 0.1 g of the hydroxyapatite-sulfate iron-confined material and place it in 50 ml of a 50 mg / L copper nitrate solution. Adjust the pH value of the copper nitrate solution to 5, control the temperature at 35°C, and shake it in a water bath oscillator at 200 rpm for 24 h to remove copper ions. After detection, the copper ion removal rate is 99.99%.

[0039] Example 8 A preparation method of the hydroxyapatite-sulfate iron-confined material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.0125 mol of sulfuric acid, with a pH value of 2.3. Slowly add 6 ml of hydrogen peroxide dropwise at 30°C for oxidation for 30 min, and then ripen at 50°C for 4 h to obtain a precursor solution; (2) Immerse 1.67 g of D001 cation exchange resin in 46.76 g of precursor solution, shake it in a water bath constant temperature oscillator at 35 °C for 24 h, then wash it with deionized water until the water is colorless. Subsequently, add the impregnated D001 cation exchange resin to 50 mL of NaOH solution with a concentration of 0.25 mol / L and continue to shake and precipitate for 24 h. Finally, wash it with deionized water until it is neutral, and then transfer it to a vacuum drying oven and dry it at 50 °C for 8 h in a nitrogen atmosphere to obtain the hydroxyphosphate sulfate iron confinement material.

[0040] Application of the prepared hydroxyphosphate sulfate iron confinement material: Take 0.1 g of the hydroxyphosphate sulfate iron confinement material and place it in 50 ml of 50 mg / L NiCl 2 solution, adjust the pH value of the NiCl 2 solution to 3, control the temperature at 32 °C, shake it in a water bath oscillator at 200 rpm for 1.5 h to remove nickel ions, and shake it at a constant speed of 200 rpm in a water bath constant temperature oscillator at 32 °C for 1.5 h. After detection, the nickel ion removal rate is 99.9%. Take 0.2 g of the hydroxyphosphate sulfate iron confinement material and place it in 50 ml of 50 mg / L methylene blue solution, adjust the pH value of the methylene blue solution to 3, then add 0.4 mol of hydrogen peroxide, control the temperature at 35 °C, shake it in a water bath oscillator at 200 rpm for 30 min to remove methylene blue. After detection, the methylene blue removal rate is 99.82%.

[0041] Example 9 Preparation method of the hydroxyphosphate sulfate iron confinement material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.0125 mol of sulfuric acid, adjust the pH value to 2.3, slowly dropwise add 6 ml of hydrogen peroxide at 30 °C for oxidation for 30 min, and then cure it at 50 °C for 4 h to obtain a precursor solution; (2) Immerse 3 g of D001 cation exchange resin in 53.44 g of precursor solution, shake it in a water bath constant temperature oscillator at 35 °C for 24 h, then wash it with deionized water until the water is colorless. Subsequently, add the impregnated D001 cation exchange resin to 50 mL of NaOH solution with a concentration of 0.25 mol / L and continue to shake and precipitate for 24 h. Finally, wash it with deionized water until it is neutral, and then transfer it to a vacuum drying oven and dry it at 50 °C for 5 h in a nitrogen atmosphere to obtain the hydroxyphosphate sulfate iron confinement material.

[0042] Application of the prepared hydroxyphosphate sulfate iron confinement material: Take 0.1 g of the hydroxyphosphate-sulfate iron-confined material and place it in 50 ml of a 50 mg / L copper nitrate solution. Adjust the pH value of the copper nitrate solution to 5, control the temperature at 35 °C, and shake it in a water bath oscillator at 200 rpm for 24 h to remove copper ions. After detection, the copper ion removal rate is 98.52%.

[0043] Take 0.2 g of the hydroxyphosphate-sulfate iron-confined material and place it in 50 ml of a 50 mg / L methylene blue solution. Adjust the pH value of the methylene blue solution to 3, then add 0.8 mol of hydrogen peroxide, control the temperature at 35 °C, and shake it in a water bath oscillator at 200 rpm for 30 min to remove methylene blue. After detection, the methylene blue removal rate is 98.82%.

[0044] Example 10 Preparation method of the hydroxyphosphate-sulfate iron-confined material, comprising the following steps: (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate according to a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.0125 mol of sulfuric acid, with a pH value of 2.3. Slowly drop 6 ml of hydrogen peroxide at 30 °C for oxidation for 30 min, and then cure at 50 °C for 4 h to obtain a precursor solution; (2) Immerse 6 g of D001 cation exchange resin in 50.1 g of the precursor solution, shake it in a water bath constant temperature oscillator at 35 °C for 24 h, wash it with deionized water until the water is colorless, then add the impregnated D001 cation exchange resin to 50 mL of a 0.25 mol / L NaOH solution and continue to shake and precipitate for 24 h. Finally, wash it with deionized water until neutral, and then transfer it to a vacuum drying oven and dry it at 50 °C for 5 h in a nitrogen atmosphere to obtain the hydroxyphosphate-sulfate iron-confined material.

[0045] Application of the prepared hydroxyphosphate-sulfate iron-confined material: Take 0.1 g of the hydroxyphosphate-sulfate iron-confined material and place it in 50 ml of a 50 mg / L copper nitrate solution. Adjust the pH value of the copper nitrate solution to 5, control the temperature at 35 °C, and shake it in a water bath oscillator at 200 rpm for 24 h to remove copper ions. After detection, the copper ion removal rate is 99.99%.

[0046] Take 0.2 g of the hydroxyphosphate-sulfate iron-confined material and place it in 50 ml of a 50 mg / L methylene blue solution. Adjust the pH value of the methylene blue solution to 3, then add 0.8 mol of hydrogen peroxide, control the temperature at 35 °C, and shake it in a water bath oscillator at 200 rpm for 30 min to remove methylene blue. After detection, the methylene blue removal rate is 99.89%.

[0047] Comparative Example 1 In step (1), sodium phosphate is not added, and the remaining steps are the same as in Example 1 to obtain a composite material.

[0048] The application of the prepared composite material is the same as in Example 1, and the removal rate of methylene blue is 75.36%, and the removal rate of copper ions is 60.98%.

[0049] From Comparative Example 1 and Example 1, it can be seen that the lack of PO 4 3- Competing with OH - for the chance of Fe 3+ results in an enhanced tendency for free ferric iron to polymerize into uncharged precipitates, and the regulation of the particle size and surface charge of the obtained polymer is correspondingly reduced. Therefore, the water purification ability of the prepared composite material is greatly weakened.

[0050] Comparative Example 2 In step (1), 0.05 mol of sulfuric acid is added, and the remaining steps are the same as in Example 1 to obtain a composite material.

[0051] The application of the prepared composite material is the same as in Example 1, and the removal rate of methylene blue is 89.56%, and the removal rate of copper ions is 87.9%.

[0052] From Comparative Example 2 and Example 1, it can be seen that the acidic environment has an impact on the entry of Fe 3+ into the carrier and its loading behavior. This environment not only regulates the adsorption behavior of Fe 3+ on the carrier, but also has a significant impact on its loading efficiency. In Comparative Example 2, too strong acidity not only affects the stability of Fe 3+ on the carrier, but also has a negative effect on its subsequent precipitation process in the sample. Excessive loading on the carrier will cause the hydrated iron oxide to lose its activity, resulting in a decrease in the overall adsorption performance and a decrease in the decolorization rate of methylene blue. Excessive hydrogen ions will affect the loading of iron ions on the carrier.

[0053] Since hydrated iron oxide is an amphoteric hydroxide and can exist in both acidic and alkaline environments, adjusting the solution pH to control its surface potential can endow it with amphoteric adsorption ability, and it can adsorb cationic pollutants such as heavy metal ions in wastewater through the formation of coordination bonds and electrostatic attraction. The acidic environment can regulate how Fe 3+ enters the carrier and its loading on the carrier, thereby affecting the adsorption ability of the sample; while too strong acidity affects its subsequent precipitation process in the sample, causing a decrease in the Cu 2+ removal rate.

[0054] Comparative Example 3 In step (1), sodium phosphate is added according to a molar ratio of sodium phosphate to ferrous sulfate heptahydrate of 0.5, and the remaining steps are the same as in Example 1.

[0055] The application of the prepared composite material was the same as that in Example 1, and the removal rate of methylene blue was 89.26%, and the removal rate of copper ions was 90.1%.

[0056] It can be seen from Comparative Example 3 and Example 1 that when the molar ratio of phosphate to iron ion is 0.125, the adsorption and oxidation performance of the sample is better. However, when the molar ratio of trisodium phosphate to ferrous sulfate heptahydrate increases, the removal rate decreases instead. This is because the adsorption of phosphate by hydrated iron oxide occurs through complexation, which is an inner-layer adsorption that is not affected by inorganic anions. On the contrary, the cationic groups fixed on the resin can adsorb phosphate through electrostatic interaction, which is an outer-layer adsorption. Phosphate competes with other inorganic anions. Excessive phosphate will cause the positively charged amount of the iron polymer solution itself to be too small, making it unable to be loaded on the carrier, resulting in a poor adsorption effect of the sample on methylene blue.

[0057] The change effect of removing copper ions is similar to that of methylene blue. When the molar ratio of trisodium phosphate to ferrous sulfate heptahydrate increases, the adsorption effect of the sample on copper ions becomes poor, and the amount of SO 4 2- is limited. Excessive PO 4 3- has a large competitiveness with OH - but lacks SO 4 2- , which will cause a risk that Fe 3+ becomes ferric phosphate precipitate. As the molar ratio of phosphate to iron ion increases, that is, the added amount of PO 4 3- increases, which makes PO 4 3- combine with Fe 3+ each other, resulting in insufficient positive charge on the surface of the precursor solution itself, making it unable to be loaded on the carrier and resulting in a poor adsorption effect of the sample.

[0058] Comparative Example 4 The concentration of NaOH added in step (2) was 3 mol / L, and the other steps were the same as those in Example 1.

[0059] The application of the prepared composite material was the same as that in Example 1, and the removal rate of methylene blue was 77.24%, and the removal rate of copper ions was 93.9%.

[0060] Comparative Example 5 The concentration of NaOH added in step (2) was 0.01 mol / L, and the other steps were the same as those in Example 1.

[0061] The application of the prepared composite material was the same as that in Example 1, and the removal rate of methylene blue was 80.11%, and the removal rate of copper ions was 91.7%.

[0062] From Comparative Example 4, Comparative Example 5 and Example 1, it can be seen that in the sample preparation step, the precipitation process is an optimization process for the volume of the crystalline product. In Example 1, by selecting an appropriate OH - concentration, it is possible to make the Fe 3+ -H 2 O-OH - complex reach an appropriate volume and enter the D001 cation exchange resin and fix it therein. When the OH - ions are too few in Comparative Example 5, the OH - ions bound by the complex will become less, and ultimately the volume of Fe 3+ -H 2 O-OH - will increase, clogging the pores of the D001 cation exchange resin, thereby resulting in a poorer effect of adsorbing heavy metal ions. When the OH - ions are too many in Comparative Example 4, PO 4 3- cannot replace some of the OH - to form a large amount of iron phosphate precipitate. Compared with the iron phosphate precipitate at a low concentration, Comparative Example 4 cannot provide a larger volume and more available bridging sites, and thus cannot make the iron aggregates in the precursor solution have smaller particle sizes and more surface active sites.

Claims

1. A method for preparing a hydroxyphosphoferric sulfate confined material, characterized in that: The following steps are involved: (1) mixing a ferrous salt solution with a phosphoric acid compound, adding sulfuric acid to adjust the pH value, adding an oxidant to oxidize, and then heat-keeping and aging to obtain a precursor solution; (2) The carrier is impregnated in a precursor solution, the impregnated carrier is preliminarily washed, and then the impregnated carrier is added to an alkaline solution for precipitation, and then washed and dried again to obtain a hydroxyferric phosphate confined material.

2. The method for preparing the hydroxyferric phosphosulfate confined material according to claim 1, characterized in that: In step (1), the oxidant is hydrogen peroxide or sodium hypochlorite, the concentration of the ferrous salt solution is 1-2 mol / L, and the ferrous salt in the ferrous salt solution is ferrous sulfate heptahydrate.

3. The method for preparing the hydroxyferric phosphate confined material according to claim 1, characterized in that: In step (1), the pH value is 1.1-2.8, and the molar ratio of the oxidant to the ferrous salt in the ferrous salt solution is 0.04-0.

06.

4. The method for preparing the hydroxyferric phosphosulfate confined material according to claim 1, characterized in that: In step (1), the phosphate compound is one of Na3PO4, NaH2PO4 or H3PO4, and the molar ratio of the phosphate compound to the ferrous salt in the ferrous salt solution is 0.075-0.

15.

5. The method for preparing the hydroxyferric phosphosulfate confined material according to claim 1, characterized in that: In step (1), the oxidation temperature is 30-35°C, the oxidation time is 0.5-1h, the insulation temperature is 50-80°C, and the insulation time is 1-8h.

6. The method for preparing the hydroxyferric phosphosulfate confined material according to claim 1, characterized in that: In step (2), the carrier is D001 cation exchange resin, and the impregnation time is 6-24 hours.

7. The method for preparing the hydroxyferric phosphosulfate confined material according to claim 1, characterized in that: In step (2), the mass ratio of the carrier to the precursor solution is 1:28-32, and the initial washing is performed using deionized water until the water becomes colorless.

8. The method for preparing the hydroxyferric phosphosulfate confined material according to claim 1, characterized in that: In step (2), the alkali solution is a NaOH solution, the concentration of the alkali solution is 0.1-1 mol / L, the mass ratio of the carrier after impregnation to the alkali solution is 1:28-32, and the precipitation time is 10-24h.

9. The method for preparing the hydroxyferric phosphosulfate confined material according to claim 1, characterized in that: The second washing in step (2) is washing with deionized water until it becomes neutral.

10. The method for preparing the hydroxyferric phosphosulfate confined material according to claim 1, characterized in that: The drying temperature in step (2) is 50-80°C and the drying time is 5-10h.

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