Preparation Method of Hydroxyphosphate Sulfate Iron Confined Material

Abstract

The present invention belongs to the technical field of composite material preparation, and specifically relates to a method for preparing a hydroxyferric phosphate confined material, comprising the following steps: (1) mixing a ferrous salt solution with a phosphate compound, adding sulfuric acid to adjust the pH value, then adding an oxidant for oxidation, and then heat-insulating and aging to obtain a precursor solution; (2) impregnating a carrier in the precursor solution, preliminarily washing the impregnated carrier, then adding the impregnated carrier to an alkaline solution for precipitation, and again washing and drying to obtain the hydroxyferric phosphate confined material. The present invention obtains fresh trivalent iron ions by oxidizing ferrous ions, thereby enhancing the performance stability of the hydroxyferric phosphate confined material and improving the environmental purification ability of the hydroxyferric phosphate confined material.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material preparation, and particularly relates to a method for preparing a hydroxyferric phosphate confined material. Background Art

[0002] Hydrated iron oxide is a compound containing water of crystallization. Its iron-based oxides can catalyze oxidants to produce active substances that decompose organic ligands. Hydrated iron oxide also has a high specific surface area, porosity, and abundant hydroxyl functional groups, making it easy to adsorb heavy metal ions after oxidative decomposition. However, hydrated iron oxide is prone to agglomeration and inactivation during preparation and application, and is difficult to handle and reuse, making it difficult to use in actual industrial wastewater treatment. By utilizing the nanoconfined structure of the framework carrier to encapsulate functional nanoparticles, the material can maintain its nanoscale size and functionality during preparation and application, enhancing its environmental purification performance.

[0003] The existing preparation process of hydrated iron oxide confined materials mostly adopts the impregnation-precipitation method, and the impregnation solution is an iron ion solution. The document Enhanced removal of tris(2-chloroethyl) phosphate using a resin-basednanocomposite hydrated iron oxide through a Fenton-like process: Capacityevaluation and pathways. Water Research. 2020. 175(5): 115655. describes this process in detail. The precursor is a disordered hydrolysis-polymerized iron aggregate, and the charge on the surface of the iron aggregate particle size is difficult to control, which affects the performance stability of this material and makes it difficult to promote and apply.

[0004] Chinese patent CN108579682A discloses a hydroxy-iron modified cationic resin composite material and its preparation method and application. The method comprises the following steps: (1) treating a cationic resin with an acid to obtain a pretreated resin; the cationic resin is a strongly acidic cationic resin; (2) dissolving ferric citrate FeC6H5O7 in an ethanol aqueous solution to obtain a FeC6H5O7 mixed solution; mixing the pretreated resin with the FeC6H5O7 mixed solution, adjusting the pH, stirring the reaction, aging, and subsequently treating the mixture to obtain a hydroxy-iron modified cationic resin composite material. This patent does not optimize the iron polymer in the ferric citrate ethanol aqueous solution as a hydroxy-iron precursor. As can be seen from the SEM image, the surface pores of the macroporous cationic resin as a carrier are all blocked, which significantly reduces the specific surface area of the product and affects the environmental purification ability of the product. Summary of the Invention

[0005] In view of the above deficiencies in the prior art, the technical problem to be solved by the present invention is: to provide a method for preparing a hydroxyferric phosphate sulfate confined material, to solve the problem that the precursor is difficult to control and affects the performance stability of the sample, and to improve the performance stability and environmental purification ability of the prepared hydroxyferric phosphate sulfate confined material.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] The method for preparing the hydroxyferric phosphate confined material of the present invention is characterized by comprising the following steps:

[0008] (1) Mixing a ferrous salt solution with a phosphoric acid compound, adding sulfuric acid to adjust the pH value, then adding an oxidant to oxidize and heat-curing to obtain a precursor solution;

[0009] (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.

[0010] in:

[0011] 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.

[0012] The pH value in the step (1) 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.

[0013] In the 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.

[0014] In the 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.

[0015] In step (2), the carrier is D001 cation exchange resin, the impregnation time is 6-24 hours, and oscillation stirring is performed during the impregnation process at a stirring speed of 100-300 rpm;

[0016] The preparation method of D001 cation exchange resin is:

[0017] Measure 30 mL of wet D001 microspheres and load them into the exchanger. Wash the resin with clean water until the water is clear. First, pass twice the volume of 1 mol / L NaOH into the exchanger and soak for 1-2 hours, then wash with clean water to a pH of 9-10. Then soak with twice the volume of 1 mol / L HCl for 1-2 hours, wash with clean water to a pH of 3-5, transfer the pretreated ion exchange resin to a vacuum drying oven, and dry it under vacuum for 5 hours to obtain D001 cation exchange resin.

[0018] 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.

[0019] In the 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 impregnated carrier to the alkali solution is 1:28-32, and the precipitation time is 10-24 hours.

[0020] The second washing in step (2) is washing with deionized water until it becomes neutral.

[0021] The drying temperature in step (2) is 50-80°C and the drying time is 5-10 hours.

[0022] The present invention combines ferrous salt with phosphate ions and introduces sulfate under acidic conditions to prevent ferrous ions from forming a colloidal solution during the conversion to ferric ions, thereby reducing the activity of ferric ions. During oxidation by an oxidant, phosphate ions and sulfate ions first combine with ferric ions, thereby making ferric ions free in the solution. The free ferric ions continuously polymerize to form aggregates, thereby obtaining a precursor solution with high ion activity. Adding a cation exchange resin as a carrier to the precursor solution can better adsorb the ferric ions on the surface of the cation exchange resin. Adding an alkali solution during the adsorption process can introduce OH - The process of combining trivalent iron ions with cation exchange resin is made more stable, thereby obtaining hydroxy phosphoferric sulfate confined material.

[0023] The beneficial effects of the present invention are:

[0024] The present invention obtains fresh trivalent iron ions by oxidizing ferrous ions, and then controls polymerization conditions such as temperature and pH value, and introduces a - Competition for Fe 3+ PO4 3- and SO4 2- , PO4 3- 、SO4 2- and OH - Both contain oxygen atoms and Fe 3+Coordination occurs, however PO4 3- and SO4 2- Volume is larger than OH - , and they carry more negative charge than OH - The spatial structures of the two are more suitable for combining multiple Fe 3+ PO4 3- with Fe 3+ The binding strength is slightly weaker than OH - Stronger than SO4 2- , using SO4 alone 2- With OH - The competitiveness is not enough, and using PO4 alone 3- With OH - The competitiveness of Fe 3+ There is a risk of becoming iron phosphate precipitate, so PO4 is required 3- and SO4 2- The synergy continuously forms polymers, thereby realizing the regulation of the particle size and surface charge of the polymer as a precursor in the precursor solution, so that the polymer can maintain a small particle size and rich surface active sites, enhancing the performance stability of the hydroxyferric phosphate sulfate confined material. When purifying water bodies, the active sites on the surface of the hydroxyferric phosphate sulfate confined material play a role, which can improve the environmental purification ability of the hydroxyferric phosphate sulfate confined material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The particle size of the precursor and PO4 3- / Fe 2+ Schematic diagram of the relationship between the change of 3- / Fe 2+ Schematic diagram of the relationship between the change of 0-0.05, B is the particle size of the precursor and PO4 3- / Fe 2+ Schematic diagram of the changing relationship when the value is 0.075-0.125;

[0026] Figure 2 The Zeta potential of the precursor changes with PO4 3- / Fe 2+ Schematic diagram of change relationship;

[0027] Figure 3 This is the SEM test result of the hydroxyferric phosphate confinement material prepared in Example 2 at 10 μm;

[0028] Figure 4 This is the SEM test result of the hydroxyferric phosphate confinement material prepared in Example 2 at 2 μm;

[0029] Figure 5This is the EDS test result of O in the hydroxyferric phosphate confinement material prepared in Example 2 at 2 μm;

[0030] Figure 6 This is the EDS test result of P in the hydroxyferric phosphate confinement material prepared in Example 2 at 2 μm;

[0031] Figure 7 This is the EDS test result of Fe in the hydroxyferric phosphate confinement material prepared in Example 2 at 2 μm;

[0032] Figure 8 This is the SEM test result of the hydroxyferric phosphate confined material after being treated with methylene blue in Example 2 at 2 μm;

[0033] Figure 9 This is the EDS test result of the hydroxyferric phosphate confined material at 2 μm after being treated with methylene blue in Example 2;

[0034] Figure 10 This is the SEM test result of the hydroxyferric phosphate confinement material at 2 μm after adsorbing copper ions in Example 2;

[0035] Figure 11 This is the EDS test result of the hydroxyferric phosphate confinement material at 2 μm after adsorbing copper ions in Example 2. DETAILED DESCRIPTION

[0036] The present invention is further illustrated by the following examples.

[0037] Configuring PO4 3- / Fe 2+ Solutions with different ratio gradients:

[0038] Dissolve 0.05 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add 0.0075 mol of sulfuric acid, and prepare six groups of identical solutions. Add trisodium phosphate to each of the six groups of solutions at a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0, 0.025, 0.05, 0.075, 0.1, and 0.125. After stirring evenly, slowly add 0.0375 mol of hydrogen peroxide dropwise at 30°C for oxidation. Then, age at 50°C for 4 hours to obtain a precursor solution. The precursor particle size and zeta potential were then measured using a nanoparticle size analyzer. The measurement results are shown in [1]. Figure 1-2 ,The results show that by regulating the molar ratio of phosphate to ferrous ion, the particle size and zeta potential of the precursor can be controlled, thereby affecting the performance of the final sample.

[0039] Example 1

[0040] The preparation method of D001 cation exchange resin is:

[0041] 30 mL of wet D001 microspheres were measured and loaded into the exchanger. The resin was washed with clean water until the water was clear. First, 1 mol / L NaOH twice the volume of the resin was passed into the exchanger to soak for 1 hour, and then washed with clean water to a pH of 9; then 1 mol / L HCl twice the volume of the resin was soaked for 1 hour, and washed with clean water to a pH of 3. The pretreated ion exchange resin was transferred to a vacuum drying oven and dried under vacuum for 5 hours to obtain D001 cation exchange resin. This D001 cation exchange resin was used in Examples 2-10.

[0042] The preparation method of hydroxyferric phosphate confined material comprises the following steps:

[0043] (1) Dissolve 0.05 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.125, then add 0.015 mol of sulfuric acid, pH value is 1.8, slowly add 6 ml of hydrogen peroxide dropwise at 30 ° C for 30 min, and then mature at 50 ° C for 4 h to obtain a precursor solution;

[0044] (2) 1.67 g of D001 cation exchange resin was immersed in 46.76 g of the precursor solution, shaken on a shaker at 200 rpm for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 1 mol / L NaOH solution and continued to shake and precipitate for 24 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 50 °C under a nitrogen atmosphere for 5 h to obtain a hydroxyphosphoferric sulfate confined material.

[0045] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0046] Take 0.2g of hydroxyphosphoferric sulfate confinement material and place it in 50ml, 50mg / L methylene blue solution, adjust the pH value of the methylene blue solution to 3, then add 0.4mol hydrogen peroxide, control the temperature at 35℃, and shake on a shaker at 200rpm for 1h to remove methylene blue. The methylene blue removal rate was tested to be 97.88%.

[0047] Take 0.1g of hydroxyphosphoferric sulfate confined material and place it in 50ml, 50mg / L copper nitrate solution, adjust the pH value of the copper nitrate solution to 5, control the temperature at 35℃, and shake on a shaker at 200rpm for 90min to remove copper ions. The copper ion removal rate was tested to be 99.1%.

[0048] Example 2

[0049] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0050] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, and then add 0.02 mol of sulfuric acid. At this time, the pH value is 1.1. Slowly add 6 ml of hydrogen peroxide at 30 ° C for oxidation for 30 minutes, and then mature at 50 ° C for 4 hours to obtain a precursor solution;

[0051] (2) 1.67 g of D001 cation exchange resin was immersed in 46.76 g of the precursor solution, shaken on a shaker at 200 rpm for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 1 mol / L NaOH solution and continued to shake and precipitate for 10 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 50 °C under a nitrogen atmosphere for 5 h to obtain a hydroxyphosphoferric sulfate confined material.

[0052] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0053] Take 0.2g of hydroxyphosphoferric sulfate confinement material and place it in 50ml, 50mg / L methylene blue solution, adjust the pH value of the methylene blue solution to 3, then add 0.4mol hydrogen peroxide, control the temperature at 35℃, and shake on a shaker at 200rpm for 1h to remove methylene blue. The methylene blue removal rate was tested to be 99.22%.

[0054] Take 0.1g of hydroxyphosphoferric sulfate confined material and place it in 50ml, 50mg / L copper nitrate solution, adjust the pH value of the copper nitrate solution to 5, control the temperature at 35℃, and shake on a shaker at 200rpm for 90min to remove copper ions. The copper ion removal rate was tested to be 99.51%.

[0055] The test results of the prepared hydroxyphosphoferric sulfate confined material and the test results after treating different solutions are shown in the figure. Figure 3-11 shown.

[0056] Example 3

[0057] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0058] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.075, and 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 minutes, and then mature at 50 ° C for 4 hours to obtain a precursor solution;

[0059] (2) 1.67 g of D001 cation exchange resin was immersed in 50.1 g of precursor solution, shaken on a shaker at 200 rpm for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 0.75 mol / L NaOH solution and continued to shake and precipitate for 12 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 60 °C under a nitrogen atmosphere for 8 h to obtain hydroxyphosphoferric sulfate confined material.

[0060] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0061] Take 0.2g of hydroxyphosphoferric sulfate confinement material and place it in 50ml, 50mg / L methylene blue solution, adjust the pH value of the methylene blue solution to 3, then add 0.4mol hydrogen peroxide, control the temperature at 35℃, and shake in a water bath oscillator at 200rpm for 1h to remove methylene blue. The methylene blue removal rate was tested to be 99.76%.

[0062] Example 4

[0063] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0064] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate at 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 minutes, and then mature at 50 ° C for 4 hours to obtain a precursor solution;

[0065] (2) 1.67 g of D001 cation exchange resin was immersed in 50.1 g of precursor solution, shaken on a shaker at 200 rpm for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 0.375 mol / L NaOH solution and continued to shake and precipitate for 24 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 80 °C under a nitrogen atmosphere for 10 h to obtain hydroxyphosphoferric sulfate confined material.

[0066] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0067] Take 0.1g of hydroxyphosphoferric sulfate confined material and place it in 50ml, 50mg / L copper nitrate solution, adjust the pH value of the copper nitrate solution to 5, control the temperature at 35℃, and shake it in a water bath oscillator at 200rpm for 1.5h to remove copper ions. The copper ion removal rate was tested to be 99.9%.

[0068] Example 5

[0069] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0070] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.015 mol of sulfuric acid, pH value is 1.8, slowly add 6 ml of hydrogen peroxide dropwise at 30 ° C for 30 min, and then mature at 50 ° C for 4 h to obtain a precursor solution;

[0071] (2) 1.67 g of D001 cation exchange resin was immersed in 53.44 g of the precursor solution, shaken on a shaker at 200 rpm for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 0.1 mol / L NaOH solution and continued to shake and precipitate for 24 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 70 ° C for 6 h under a nitrogen atmosphere to obtain a hydroxyphosphoferric sulfate confined material.

[0072] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0073] Take 0.2g of hydroxyphosphoferric sulfate confinement material and place it in 50ml, 50mg / L methylene blue solution, adjust the pH value of the methylene blue solution to 3, then add 0.4mol hydrogen peroxide, control the temperature at 35℃, and shake in a water bath oscillator at 200rpm for 1h to remove methylene blue. The methylene blue removal rate was tested to reach 99.76%.

[0074] Example 6

[0075] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0076] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.15, then add 0.01 mol of sulfuric acid, pH value is 2.8, slowly add 6 ml of hydrogen peroxide dropwise at 30 ° C for 30 min, and then mature at 50 ° C for 4 h to obtain a precursor solution;

[0077] (2) 1.67 g of D001 cation exchange resin was immersed in 53.44 g of precursor solution, shaken on a shaker at 200 rpm for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 0.25 mol / L NaOH solution and continued to shake and precipitate for 24 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 50 °C under a nitrogen atmosphere for 5 h to obtain hydroxyphosphoferric sulfate confined material.

[0078] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0079] Take 0.1g of hydroxyphosphoferric sulfate confined material and place it in 50ml, 50mg / L copper nitrate solution, adjust the pH value of the copper nitrate solution to 5, control the temperature at 35℃, and shake it in a water bath oscillator at 200rpm for 1.5h to remove copper ions. The copper ion removal rate was tested to be 99.9%.

[0080] Example 7

[0081] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0082] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.0125 mol of sulfuric acid, pH value is 2.3, slowly add 6 ml of hydrogen peroxide dropwise at 35 ° C for 30 min, and then mature at 50 ° C for 4 h to obtain a precursor solution;

[0083] (2) 1.67 g of D001 cation exchange resin was immersed in 50.1 g of the precursor solution, shaken on a shaker at 200 rpm for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 0.25 mol / L NaOH solution and continued to shake and precipitate for 24 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 50 °C under a nitrogen atmosphere for 5 h to obtain a hydroxyphosphoferric sulfate confined material.

[0084] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0085] Take 0.1g of hydroxyphosphoferric sulfate confined material and place it in 50ml, 50mg / L copper nitrate solution, adjust the pH value of the copper nitrate solution to 5, control the temperature at 35℃, and shake it in a water bath oscillator at 200rpm for 24h to remove copper ions. The copper ion removal rate was tested to be 99.99%.

[0086] Example 8

[0087] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0088] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.0125 mol of sulfuric acid, pH value is 2.3, slowly add 6 ml of hydrogen peroxide dropwise at 30 ° C for 30 min, and then mature at 50 ° C for 4 h to obtain a precursor solution;

[0089] (2) 1.67 g of D001 cation exchange resin was immersed in 46.76 g of precursor solution, shaken in a water bath constant temperature oscillator at 35 ° C for 24 h, and then washed with deionized water until the water was colorless. Then, the impregnated D001 cation exchange resin was added to 50 mL of 0.25 mol / L NaOH solution and continued to shake and precipitate for 24 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 50 ° C for 8 h under a nitrogen atmosphere to obtain hydroxyphosphoferric sulfate confined material.

[0090] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0091] Take 0.1g of hydroxyphosphoferric sulfate confined material and place it in 50ml, 50mg / L NiCl2 solution, adjust the pH value of the NiCl2 solution to 3, control the temperature at 32℃, and shake it in a water bath shaker at 200rpm for 1.5h to remove nickel ions. Shake it in a 32℃ water bath constant temperature shaker at a constant speed of 200rpm for 1.5h. The nickel ion removal rate was tested to be 99.9%.

[0092] Take 0.2g of hydroxyphosphoferric sulfate confinement material and place it in 50ml, 50mg / L methylene blue solution, adjust the pH value of the methylene blue solution to 3, then add 0.4mol hydrogen peroxide, control the temperature at 35℃, and shake in a water bath oscillator at 200rpm for 30min to remove methylene blue. The methylene blue removal rate was tested to be 99.82%.

[0093] Example 9

[0094] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0095] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.0125 mol of sulfuric acid, pH value is 2.3, slowly add 6 ml of hydrogen peroxide dropwise at 30 ° C for 30 min, and then mature at 50 ° C for 4 h to obtain a precursor solution;

[0096] (2) 3 g of D001 cation exchange resin was immersed in 53.44 g of precursor solution, shaken in a water bath constant temperature oscillator at 35 °C for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 0.25 mol / L NaOH solution and continued to shake and precipitate for 24 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 50 °C under a nitrogen atmosphere for 5 h to obtain hydroxyphosphoferric sulfate confined material.

[0097] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0098] Take 0.1g of hydroxyphosphoferric sulfate confined material and place it in 50ml, 50mg / L copper nitrate solution, adjust the pH value of the copper nitrate solution to 5, control the temperature at 35℃, and shake in a water bath oscillator at 200rpm for 24h to remove copper ions. The copper ion removal rate was tested to be 98.52%.

[0099] Take 0.2g of hydroxyphosphoferric sulfate confinement material and place it in 50ml, 50mg / L methylene blue solution, adjust the pH value of the methylene blue solution to 3, then add 0.8mol hydrogen peroxide, control the temperature at 35℃, and shake in a water bath oscillator at 200rpm for 30min to remove methylene blue. The methylene blue removal rate was tested to be 98.82%.

[0100] Example 10

[0101] The preparation method of hydroxyferric phosphate confinement material comprises the following steps:

[0102] (1) Dissolve 0.1 mol of ferrous sulfate heptahydrate in 50 ml of deionized water, add trisodium phosphate in a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.1, then add 0.0125 mol of sulfuric acid, pH value is 2.3, slowly add 6 ml of hydrogen peroxide dropwise at 30 ° C for 30 min, and then mature at 50 ° C for 4 h to obtain a precursor solution;

[0103] (2) 6 g of D001 cation exchange resin was immersed in 50.1 g of precursor solution, shaken in a water bath constant temperature oscillator at 35 °C for 24 h, and then washed with deionized water until the water was colorless. The impregnated D001 cation exchange resin was then added to 50 mL of 0.25 mol / L NaOH solution and continued to shake and precipitate for 24 h. Finally, it was washed with deionized water until neutral, and then transferred to a vacuum drying oven and dried at 50 °C under a nitrogen atmosphere for 5 h to obtain hydroxyphosphoferric sulfate confined material.

[0104] Application of the prepared hydroxyphosphoferric sulfate confined material:

[0105] Take 0.1g of hydroxyphosphoferric sulfate confined material and place it in 50ml, 50mg / L copper nitrate solution, adjust the pH value of the copper nitrate solution to 5, control the temperature at 35℃, and shake it in a water bath oscillator at 200rpm for 24h to remove copper ions. The copper ion removal rate was tested to be 99.99%.

[0106] Take 0.2g of hydroxyphosphoferric sulfate confinement material and place it in 50ml, 50mg / L methylene blue solution, adjust the pH value of the methylene blue solution to 3, then add 0.8mol hydrogen peroxide, control the temperature at 35℃, and shake in a water bath oscillator at 200rpm for 30min to remove methylene blue. The methylene blue removal rate was tested to be 99.89%.

[0107] Comparative Example 1

[0108] In step (1), trisodium phosphate was not added, and the remaining steps were the same as in Example 1 to obtain a composite material.

[0109] The prepared composite material was used in the same manner as in Example 1, and the removal rates of methylene blue and copper ions were 75.36% and 60.98%, respectively.

[0110] From Comparative Example 1 and Example 1, it can be seen that the lack of PO4 3- With OH - Competition for Fe 3+ The opportunity for the free trivalent iron to aggregate into uncharged precipitates is strengthened, and the control of the particle size and surface charge of the obtained aggregates is correspondingly reduced. Therefore, the purification ability of the prepared composite material on water bodies is greatly weakened.

[0111] Comparative Example 2

[0112] 0.05 mol of sulfuric acid was added in step (1), and the remaining steps were the same as those in Example 1 to obtain a composite material.

[0113] The prepared composite material was used in the same manner as in Example 1, and the removal rates of methylene blue and copper ions were 89.56% and 87.9%, respectively.

[0114] From Comparative Example 2 and Example 1, it can be seen that the acidic environment has a great influence on Fe 3+ The environment not only regulates the Fe 3+ The adsorption behavior on the carrier also has a significant impact on its loading efficiency. In Comparative Example 2, the acidity is too strong, which not only affects the Fe 3+ The stability of the carrier also has a negative impact 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 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.

[0115] Since hydrated iron oxide is an amphoteric hydroxide, it can exist in both acidic and alkaline environments. By adjusting the pH of the solution to control its surface potential, it can have amphoteric adsorption capacity and can adsorb cationic pollutants such as heavy metal ions in wastewater by forming coordination bonds and electrostatic attraction. 3+ How it enters the carrier and its load on the carrier will affect the adsorption capacity of the sample; if the acid is too strong, it will affect the subsequent sample precipitation process, making Cu 2+ The removal rate decreased.

[0116] Comparative Example 3

[0117] In step (1), trisodium phosphate is added at a molar ratio of trisodium phosphate to ferrous sulfate heptahydrate of 0.5, and the remaining steps are the same as in Example 1.

[0118] The prepared composite material was used in the same manner as in Example 1, and the removal rates of methylene blue and copper ions were 89.26% and 90.1%, respectively.

[0119] As shown in Comparative Example 3 and Example 1, when the phosphate radical and iron ion molar ratio is 0.125, the sample adsorption oxidation performance is better, but after the trisodium phosphate and ferrous sulfate heptahydrate molar ratio increases, the removal rate becomes smaller instead. This is because hydrated iron oxide is carried out by complexation to phosphate radical adsorption, which belongs to the inner layer adsorption not affected by inorganic anions; In contrast, the cationic groups fixed on the resin can utilize electrostatic action to adsorb phosphate radical, which is outer layer adsorption. There is competition between phosphate and other inorganic anions. The excessively high positive charge of phosphate radical can cause the iron polymer solution itself to be too little, making it impossible to be loaded on the carrier, so that the sample adsorption methylene blue effect is deteriorated.

[0120] The 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 worse, and SO4 2- Limited quantity, extra PO4 3- With OH - The competitiveness is greater but lacks SO4 2- , which will make Fe 3+ There is a risk of becoming iron phosphate precipitate, the molar ratio of phosphate to iron ion increases, that is, the added PO4 3- Increase, making PO4 3- with Fe 3+ The combination with each other results in insufficient positive charge on the surface of the precursor solution itself, making it unable to be loaded on the carrier and causing the adsorption effect of the sample to deteriorate.

[0121] Comparative Example 4

[0122] The concentration of NaOH added in step (2) is 3 mol / L, and the remaining steps are the same as in Example 1.

[0123] The prepared composite material was used in the same manner as in Example 1, and the removal rates of methylene blue and copper ions were 77.24% and 93.9%, respectively.

[0124] Comparative Example 5

[0125] The concentration of NaOH added in step (2) is 0.01 mol / L, and the remaining steps are the same as in Example 1.

[0126] The prepared composite material was used in the same manner as in Example 1, and the removal rates of methylene blue and copper ions were 80.11% and 91.7%, respectively.

[0127] 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, the appropriate OH - concentration, which can make Fe 3+ -H2O-OH - The complex reaches a suitable volume and enters the D001 cation exchange resin, where it is fixed. - When there are too few ions, the OH - will become less and eventually lead to Fe 3+ -H2O-OH - The volume becomes larger, blocking the pores of D001 cation exchange resin, which leads to a decrease in its adsorption effect of heavy metal ions. - When there are too many ions, PO4 3- Unable to replace some OH - , forming a large amount of iron phosphate precipitate. Compared with the low-concentration iron phosphate precipitate, Comparative Example 4 cannot provide a larger volume and more action sites that can be used as bridges, and cannot make the iron polymers in the precursor solution have a smaller particle size and more surface active sites.

Claims

1. A method for preparing a hydroxyferric phosphate 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, then adding an oxidant to oxidize and heat-curing to obtain a precursor solution; (2) impregnating the support in the precursor solution, preliminarily washing the impregnated support, then adding the impregnated support into an alkaline solution for precipitation, washing and drying again to obtain a hydroxyferric phosphate confined material; In step (1), the pH value is 1.1-2.8, 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; 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 impregnated carrier to the alkali solution is 1:28-32, and the precipitation time is 10-24 hours.

2. The method for preparing the hydroxyferric phosphate confined material according to claim 1, wherein: 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, wherein: In step (1), 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 phosphate confined material according to claim 1, wherein: 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.

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

6. The method for preparing the hydroxyferric phosphate 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.

7. The method for preparing the hydroxyferric phosphate confined material according to claim 1, characterized in that: The second washing in step (2) is to use deionized water to wash until neutral.

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

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