Efficient polyferric sulfate production method

Abstract

The invention relates to the technical field of polyferric sulfate, in particular to an efficient polyferric sulfate production method. The high-efficiency polyferric sulfate production method comprises the following steps: (1) preparing microbial particles; (2) preparing a synergist; and (3) oxidizing the microbial particles by taking ferrous sulfate heptahydrate as a raw material, and after the conversion rate of ferrous ions is greater than or equal to 99.5%, magnetically separating and recycling the microbial particles, and uniformly mixing with a synergist to obtain the high-efficiency polyferric sulfate.

Description

Technical Field

[0001] This invention relates to the field of polyferric sulfate technology, and specifically to a high-efficiency method for producing polyferric sulfate. Background Technology

[0002] Polyferric sulfate (PFLS) is a novel, high-quality, and highly efficient inorganic polymeric flocculant based on iron salts. It possesses strong adsorption capacity and outperforms traditional inorganic water purifiers in water purification. PFLS exhibits excellent coagulation properties, stable chemical properties, rapid sedimentation, and a wide applicable pH range, making it widely used in the purification of drinking water, various industrial waters, industrial wastewater, and municipal sewage. Currently, PFLS is primarily available in two forms: liquid (total iron ≥11%) and solid (total iron ≥19%). The solid form is produced by converting the liquid product into a solid state through drying processes. Its advantage lies in its cost-effectiveness for long-distance transportation. However, before use, the solid product must be diluted and reconstituted with water in a specific ratio to return it to a liquid state. Furthermore, due to process limitations, it is generally difficult to convert 100% of the effective components into a solid during the liquid-to-solid conversion process. Additionally, the degree of polymerization is damaged during high-temperature drying. Therefore, the viscosity of the liquid product is higher than that of the diluted liquid product after high-temperature drying. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a highly efficient method for producing polyferric sulfate.

[0004] This invention is achieved through the following technical solution: A method for producing high-efficiency polyferric sulfate includes the following steps: (1) Preparation of microbial particles: (11) Under stirring conditions, FeCl3·6H2O and sodium citrate were added to ethylene glycol in sequence and mixed thoroughly. Sodium acetate was added and stirred to react. The mixture was then transferred to a high-pressure reactor and reacted at 200℃ for 8-10 h. After natural cooling, magnetic separation was performed, magnetic components were collected, washed with deionized water and ethanol, and dried under vacuum to obtain Fe3O4 magnetic microspheres. (12) Mix deionized water and anhydrous ethanol, add Fe3O4 magnetic microspheres obtained in step (11), disperse ultrasonically for 15-20 min, add 25wt% ammonia water dropwise while stirring, continue stirring for 30 min, add tetraethyl orthosilicate (TEOS) dropwise, stir and react for 24 h, collect the magnetic part by magnetic separation, wash with ethanol and deionized water, and dry under vacuum to obtain Fe3O4@SiO2; (13) Take the Fe3O4@SiO2 obtained in step (12) and 3-aminopropyltrimethoxysilane (APTMS) and ultrasonically disperse them in ethanol. Heat at 80°C for 6-8 h. The magnetically separated product is washed with anhydrous ethanol and deionized water and dried under vacuum to obtain Fe3O4@SiO2-NH2. (14) Under a nitrogen atmosphere, protocatechuic acid (PCA) was dissolved in ethanol to obtain a PCA solution. EDC·HCl was dissolved in MES buffer solution with pH=5.5. The PCA solution was added and the reaction was stirred. NHS was then added and stirred in an ice-water bath in the dark for 1 h. Fe3O4@SiO2-NH2 obtained in step (13) was added and stirred in the dark at room temperature for 24 h. The mixture was magnetically separated, washed with deionized water and ethanol, and dried under vacuum to obtain Fe3O4@SiO2-PCA. (15) Dissolve the carboxyl group of mercaptopolyethylene glycol in 10 mM pH 8.5 tris-HCl buffer solution, add Fe3O4@SiO2-PCA obtained in step (14) under stirring at 1200 rpm, stir for 1 h, purify by magnetic separation, wash with deionized water, and dry under vacuum to obtain Fe3O4@SiO2-SH-PEG-COOH; (16) Take the logarithmic growth phase of *Acidithiobacillus ferrooxidans*, wash with 0.01 M sulfate buffer at pH 2.5, and resuspend in PBS buffer at pH 5 to obtain a concentration of 5 × 10⁻⁶. 8 CFU / mL bacterial suspension, Fe3O4@SiO2-SH-PEG-COOH obtained in step (15) was dispersed in PBS buffer at pH 5, EDC·HCl was added, stirred for 10 min, NHS was added and stirred for 30 min, added to bacterial suspension, reacted at 30℃ for 4-6 h, magnetic separation was performed, washed, and microbial particles were obtained; (2) Preparation of synergists: (21) Gallic acid (GA) was added to deionized water, nitrogen gas was introduced, and the mixture was stirred and dissolved at 50°C. The pH of the solution was adjusted to 12 with 20 wt% NaOH solution. The solution was heated to 80°C, and 65 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride solution was added dropwise to maintain the pH of the solution at 12. The reaction was carried out for 4 h, cooled to room temperature, neutralized with HCl solution, added to acetone, and the precipitate was added to ethanol and mixed well. The mixture was filtered, recrystallized, and dried under vacuum to obtain GA-CHMAC. (22) Dissolve EDC·HCl in MES buffer at pH 5.5, add GA-CHMAC obtained in step (21), stir for 10 min, add NHS, stir for 1 h, add polylysine, stir for 12 h, dialyze in deionized water for 24 h, freeze dry to obtain synergist. (3) FeSO4·7H2O was prepared according to 9 g / L Fe2+ The concentration of [amount] was added to 9K medium and mixed thoroughly to obtain a mixed nutrient solution. Microbial particles were then inoculated into the mixed nutrient solution at a cell density of 2 × 10⁻⁶. 8 cfu / mL, adjust pH to 1.5-2, stir at 25-30℃ and 120 r / min, when Fe 2+ When the conversion rate reaches 85%, the solution is inoculated into freshly prepared mixed nutrient solution at an inoculum volume of 10%. 2+ The concentration is gradually increased, and the process is continuously acclimatized until the reaction cycle stabilizes, resulting in seed liquid. (4) FeSO4·7H2O was prepared according to 40 g / L Fe 2+ The concentration of ferrous sulfate was added to 9K medium and mixed well. The seed liquid obtained in step (3) was inoculated at an inoculation amount of 10%. The pH was adjusted to 1.5-2. The reaction was carried out at 25-30℃ and 120 r / min. The content of ferrous ions was measured. When the ferrous ion conversion rate was ≥99.5%, the microbial particles were magnetically separated and recovered. The microbial particles were mixed with 5 mg / mL of synergist aqueous solution at a volume ratio of 100:1 to obtain high-efficiency polyferric sulfate.

[0005] Further, in step (11), the mass concentration of FeCl3·6H2O in ethylene glycol is 25-30 mg / mL.

[0006] Further, in step (11), the mass ratio of FeCl3·6H2O, sodium citrate and sodium acetate is 4:1:6.

[0007] Further, in step (12), the ratio of Fe3O4 magnetic microspheres, deionized water, anhydrous ethanol and 25wt% ammonia is 1 g:20 mL:60 mL:1 mL.

[0008] Furthermore, in step (12), the ratio of TEOS to Fe3O4 magnetic microspheres is 1 mL:1 g.

[0009] Furthermore, in step (13), the mass ratio of Fe3O4@SiO2 to APTMS is 1:1.

[0010] Further, in step (13), the mass concentration of Fe3O4@SiO2 in ethanol is 50 mg / mL.

[0011] Further, in step (14), the mass ratio of protocatechuic acid to Fe3O4@SiO2-NH2 is 1:1-1.5.

[0012] Further, in step (14), the mass concentration of EDC·HCl in the MES buffer solution is 20 mg / mL.

[0013] Further, in step (14), the mass concentration of protocatechuic acid in ethanol is 0.1 g / mL.

[0014] Further, in step (14), the mass ratio of protocatechuic acid, EDC·HCl and NHS is 0.4:0.5:0.3.

[0015] Further, in step (15), the mass concentration of the mercaptopolyethylene glycol carboxyl group in the tris-HCl buffer solution is 40 mg / L.

[0016] Further, in step (15), the mass ratio of the mercapto polyethylene glycol carboxyl group to Fe3O4@SiO2-PCA is 6:1.

[0017] Further, in step (16), the mass concentration of Fe3O4@SiO2-SH-PEG-COOH in PBS buffer is 1 mg / mL.

[0018] Further, in step (16), the mass ratio of Fe3O4@SiO2-SH-PEG-COOH, EDC·HCl and NHS is 1:10:6.

[0019] Further, in step (16), the ratio of Fe3O4@SiO2-SH-PEG-COOH to bacterial suspension is 2 mg:1 mL.

[0020] Further, in step (21), the mass concentration of gallic acid in deionized water is 10 mg / mL.

[0021] Further, in step (21), the mass ratio of gallic acid to 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1:4.

[0022] Further, in step (22), the mass ratio of GA-CHMAC to polylysine is 1:2.

[0023] Further, in step (22), the mass ratio of GA-CHMAC, EDC·HCl and NHS is 1:0.5:0.3.

[0024] Further, in step (22), the mass concentration of GA-CHMAC in the MES buffer is 10 mg / mL.

[0025] Furthermore, the 9K culture medium consists of the following components: 3 g / L ammonium sulfate, 0.5 g / L dipotassium hydrogen phosphate, 0.1 g / L potassium chloride, 0.5 g / L magnesium sulfate heptahydrate, 0.01 g / L calcium nitrate, with the remainder being water.

[0026] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a highly efficient method for producing polyferric sulfate. By using magnetic microbial particles with a specific structure and introducing a synergist, it achieves efficient immobilization and magnetic separation of microorganisms, resulting in efficient oxidative conversion of ferrous ions and a significant improvement in the flocculation and antibacterial properties of the final product. This invention constructs core-shell structured magnetic microbial particles (Fe3O4@SiO2-SH-PEG-COOH immobilized *Thiobacillus ferrooxidans*). The magnetic core (Fe3O4) imparts magnetism to the particles, allowing for magnetic separation and recovery of the microbial particles after the reaction. The Fe3O4 surface is coated with SiO2. The SiO2 layer improves the chemical stability and biocompatibility of the particles, protecting the magnetic core from corrosion in acidic environments. The SiO2 coating on the Fe3O4 surface effectively enhances the chemical stability of the particles, protects the magnetic core from corrosion in acidic reaction environments, and provides a suitable carrier surface for microbial immobilization due to its good biocompatibility. This invention utilizes APTMS to modify amino groups on the surface of Fe3O4@SiO2, which then react with the carboxyl groups of protocatechuic acid. The protocatechuic acid groups provide catechol groups, enhancing the affinity with microbial cell walls. Subsequently, through the reaction of the thiol groups of thiol-based polyethylene glycol carboxyl groups with the catechol groups, polyethylene glycol chains are grafted onto the Fe3O4@SiO2-NH2 surface, forming a hydrophilic protective layer. This reduces microbial aggregation, improves dispersibility and activity retention. The long polyethylene glycol chains form a hydrophilic protective layer, effectively reducing the aggregation of microbial particles in the reaction system, improving their dispersion stability, and creating a more suitable microenvironment for immobilized microorganisms, which is beneficial for maintaining their high biological activity and catalytic efficiency. The resulting microbial particles immobilize *Thiobacillus ferrooxidans* on the surface of a functionalized magnetic carrier. When the immobilized microorganisms catalyze the oxidation of ferrous ions, the active sites are fully exposed, the conversion rate is stable, and the particles can be reused. The introduction of the synergist in this invention significantly enhances flocculation performance and antibacterial properties. The synergist introduces multiple quaternary ammonium salt groups by grafting the phenolic hydroxyl groups of gallic acid with 3-chloro-2-hydroxypropyltrimethylammonium chloride, thereby improving the flocculation effect. Then, it undergoes an amide reaction with polylysine, with GA-CHMAC grafted onto the polylysine backbone. As a long-chain polymer, polylysine can provide adsorption bridging ability, thereby improving the flocculation effect. Furthermore, both the quaternary ammonium salt groups and polylysine chains in the synergist molecule have antibacterial effects, effectively inhibiting bacteria such as Escherichia coli and Staphylococcus aureus. The synergist is combined with polyferric sulfate to form a synergistic effect, significantly improving the flocculation effect and antibacterial properties, and increasing the removal efficiency of pollutants. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This demonstrates the flocculation effect of the high-efficiency polyferric sulfate described in Examples 1-3 and Comparative Examples 3-4 of the present invention. Figure 2 This demonstrates the antibacterial effect of the highly efficient polyferric sulfate described in Examples 1-3 and Comparative Examples 3-4 of the present invention. Figure 3 This refers to the efficiency of the methods described in Embodiments 1-3 and Comparative Examples 1-2 of the present invention; Figure 4 This is a transmission electron microscope (TEM) image of Fe3O4@SiO2-NH2 described in Example 1 of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. However, this invention is not limited to the following embodiments. It should be noted that, unless otherwise specified, all chemical reagents involved in this invention are purchased through commercial channels.

[0030] Example 1: A method for producing high-efficiency polyferric sulfate, comprising the following steps: (1) Preparation of microbial particles: (11) Under stirring conditions, 3 g of FeCl3·6H2O and 0.75 g of sodium citrate were added to 100 mL of ethylene glycol and mixed thoroughly. 4.5 g of sodium acetate was added and stirred to react. The mixture was then transferred to a high-pressure reactor and reacted at 200 °C for 10 h. After natural cooling, magnetic separation was performed, and the magnetic components were collected. The mixture was washed with deionized water and ethanol and dried under vacuum to obtain Fe3O4 magnetic microspheres. (12) Mix 20 mL of deionized water and 60 mL of anhydrous ethanol, add 1 g of Fe3O4 magnetic microspheres obtained in step (11), disperse by ultrasonication for 20 min, add 1 mL of 25 wt% ammonia water dropwise while stirring, continue stirring for 30 min, add 1 mL of tetraethyl orthosilicate (TEOS) dropwise, stir and react for 24 h, collect the magnetic part by magnetic separation, wash with ethanol and deionized water, and dry under vacuum to obtain Fe3O4@SiO2; (13) Take 1 g of Fe3O4@SiO2 obtained in step (12) and 1 g of 3-aminopropyltrimethoxysilane (APTMS) and ultrasonically disperse them in 20 mL of ethanol. Heat at 80 °C for 8 h. The magnetically separated product is washed with anhydrous ethanol and deionized water and dried under vacuum to obtain Fe3O4@SiO2-NH2. The transmission electron microscope image is shown below. Figure 4 As shown, the Fe3O4@SiO2-NH2 particles are uniformly dispersed, and the surface of Fe3O4 is uniformly coated with SiO2. (14) Under a nitrogen atmosphere, 1 g of protocatechuic acid (PCA) was dissolved in 10 mL of ethanol to obtain a PCA solution. 1.25 g of EDC·HCl was dissolved in 62.5 mL of MES buffer solution with pH=5.5. The PCA solution was added and the reaction was stirred. Then 0.75 g of NHS was added and stirred in an ice-water bath in the dark for 1 h. 1.5 g of Fe3O4@SiO2-NH2 obtained in step (13) was added and stirred in the dark at room temperature for 24 h. The mixture was magnetically separated, washed with deionized water and ethanol, and dried under vacuum to obtain Fe3O4@SiO2-PCA. (15) Dissolve 6 g of mercaptopolyethylene glycol carboxyl group in 150 mL of 10 mM pH 8.5 tris-HCl buffer solution, add 1 g of Fe3O4@SiO2-PCA obtained in step (14) under stirring at 1200 rpm, stir for 1 h, purify by magnetic separation, wash with deionized water, and dry under vacuum to obtain Fe3O4@SiO2-SH-PEG-COOH; (16) Take the logarithmic growth phase of *Acidithiobacillus ferrooxidans*, wash with 0.01 M sulfate buffer at pH 2.5, and resuspend in PBS buffer at pH 5 to obtain a concentration of 5 × 10⁻⁶. 8 CFU / mL bacterial suspension, Fe3O4@SiO2-SH-PEG-COOH 0.5 g obtained in step (15) was dispersed in 500 mL of PBS buffer at pH 5, EDC·HCl 5 g was added, stirred for 10 min, NHS 3 g was added and stirred for 30 min, 250 mL of bacterial suspension was added, reacted at 30℃ for 6 h, magnetic separation was performed, washed, and microbial particles were obtained; (2) Preparation of synergists: (21) Take 1 g of gallic acid (GA) and add it to 100 mL of deionized water. Purge with nitrogen gas and stir at 50 °C to dissolve. Adjust the pH of the solution to 12 with 20 wt% NaOH solution. Heat to 80 °C and add 65 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride solution dropwise. The mass ratio of gallic acid to 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1:4. Maintain the pH of the solution at 12 and react for 4 h. Cool to room temperature, neutralize with HCl solution, add to acetone, recrystallize the precipitate in ethanol, and dry under vacuum to obtain GA-CHMAC. (22) Dissolve 0.5 g of EDC·HCl in 100 mL of MES buffer at pH 5.5, add 1 g of GA-CHMAC obtained in step (21), stir for 10 min, add 0.3 g of NHS, stir for 1 h, add 2 g of polylysine, stir for 12 h, dialyze in deionized water for 24 h, freeze dry to obtain the synergist; (3) FeSO4·7H2O was prepared according to 9 g / L Fe 2+ The concentration of [amount] was added to 9K medium and mixed thoroughly to obtain a mixed nutrient solution. Microbial particles were then inoculated into the mixed nutrient solution at a cell density of 2 × 10⁻⁶. 8 cfu / mL, adjust pH to 2, stir at 30℃ and 120 rpm, when Fe 2+ When the conversion rate reaches 85%, the solution is inoculated into freshly prepared mixed nutrient solution at an inoculum volume of 10%. 2+ The concentration is gradually increased, and the process is continuously acclimatized until the reaction cycle stabilizes, resulting in seed liquid. (4) FeSO4·7H2O was prepared according to 40 g / L Fe 2+ The concentration of the solution was added to the 9K medium and mixed well. The seed solution obtained in step (3) was inoculated at an inoculation rate of 10%. The pH was adjusted to 2. The reaction was stirred at 30℃ and 120 r / min. The content of ferrous ions was measured. When the ferrous ion conversion rate was ≥99.5%, the microbial particles were magnetically separated and recovered. The solution was mixed with 5 mg / mL of synergist aqueous solution at a volume ratio of 100:1 to obtain high-efficiency polyferric sulfate. The 9K medium consisted of the following components: 3 g / L ammonium sulfate, 0.5 g / L dipotassium hydrogen phosphate, 0.1 g / L potassium chloride, 0.5 g / L magnesium sulfate heptahydrate, 0.01 g / L calcium nitrate, and the remainder was water.

[0031] Example 2: A method for producing high-efficiency polyferric sulfate, comprising the following steps: (1) Preparation of microbial particles: (11) Under stirring conditions, 2.5 g of FeCl3·6H2O and 0.625 g of sodium citrate were added to 100 mL of ethylene glycol and mixed thoroughly. 3.75 g of sodium acetate was added and stirred to react. The mixture was then transferred to a high-pressure reactor and reacted at 200 °C for 8 h. After natural cooling, magnetic separation was performed, and the magnetic components were collected. The mixture was washed with deionized water and ethanol and dried under vacuum to obtain Fe3O4 magnetic microspheres. (12) Mix 20 mL of deionized water and 60 mL of anhydrous ethanol, add 1 g of Fe3O4 magnetic microspheres obtained in step (11), disperse by ultrasonication for 15 min, add 1 mL of 25 wt% ammonia water dropwise while stirring, continue stirring for 30 min, add 1 mL of tetraethyl orthosilicate (TEOS) dropwise, stir and react for 24 h, collect the magnetic part by magnetic separation, wash with ethanol and deionized water, and dry under vacuum to obtain Fe3O4@SiO2; (13) Take 1 g of Fe3O4@SiO2 obtained in step (12) and 1 g of 3-aminopropyltrimethoxysilane (APTMS) and disperse them in 20 mL of ethanol by ultrasonication. Heat at 80 °C for 6 h. The magnetically separated product is washed with anhydrous ethanol and deionized water and dried under vacuum to obtain Fe3O4@SiO2-NH2. (14) Under a nitrogen atmosphere, 1 g of protocatechuic acid (PCA) was dissolved in 10 mL of ethanol to obtain a PCA solution. 1.25 g of EDC·HCl was dissolved in 62.5 mL of MES buffer solution with pH=5.5. The PCA solution was added and the reaction was stirred. Then 0.75 g of NHS was added and stirred in an ice-water bath in the dark for 1 h. 1 g of Fe3O4@SiO2-NH2 obtained in step (13) was added and stirred in the dark at room temperature for 24 h. The mixture was magnetically separated, washed with deionized water and ethanol, and dried under vacuum to obtain Fe3O4@SiO2-PCA. (15) Dissolve 6 g of mercaptopolyethylene glycol carboxyl group in 150 mL of 10 mM pH 8.5 tris-HCl buffer solution, add 1 g of Fe3O4@SiO2-PCA obtained in step (14) under stirring at 1200 rpm, stir for 1 h, purify by magnetic separation, wash with deionized water, and dry under vacuum to obtain Fe3O4@SiO2-SH-PEG-COOH; (16) Take the logarithmic growth phase of *Acidithiobacillus ferrooxidans*, wash with 0.01 M sulfate buffer at pH 2.5, and resuspend in PBS buffer at pH 5 to obtain a concentration of 5 × 10⁻⁶. 8CFU / mL bacterial suspension, Fe3O4@SiO2-SH-PEG-COOH 0.5 g obtained in step (15) was dispersed in 500 mL of PBS buffer at pH 5, EDC·HCl 5 g was added, stirred for 10 min, NHS 3 g was added and stirred for 30 min, added to 250 mL of bacterial suspension, reacted at 30℃ for 4-6 h, magnetically separated, washed, and microbial particles were obtained; (2) Preparation of synergists: (21) Take 1 g of gallic acid (GA) and add it to 100 mL of deionized water. Purge with nitrogen gas and stir at 50 °C to dissolve. Adjust the pH of the solution to 12 with 20 wt% NaOH solution. Heat to 80 °C and add 65 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride solution dropwise. The mass ratio of gallic acid to 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1:4. Maintain the pH of the solution at 12 and react for 4 h. Cool to room temperature, neutralize with HCl solution, add to acetone, recrystallize the precipitate in ethanol, and dry under vacuum to obtain GA-CHMAC. (22) Dissolve 0.5 g of EDC·HCl in 100 mL of MES buffer at pH 5.5, add 1 g of GA-CHMAC obtained in step (21), stir for 10 min, add 0.3 g of NHS, stir for 1 h, add 2 g of polylysine, stir for 12 h, dialyze in deionized water for 24 h, freeze dry to obtain the synergist; (3) FeSO4·7H2O was prepared according to 9 g / L Fe 2+ The concentration of [amount] was added to 9K medium and mixed thoroughly to obtain a mixed nutrient solution. Microbial particles were then inoculated into the mixed nutrient solution at a cell density of 2 × 10⁻⁶. 8 cfu / mL, adjust pH to 1.5, stir at 25℃ and 120 rpm, when Fe 2+ When the conversion rate reaches 85%, the solution is inoculated into freshly prepared mixed nutrient solution at an inoculum volume of 10%. 2+ The concentration is gradually increased, and the process is continuously acclimatized until the reaction cycle stabilizes, resulting in seed liquid. (4) FeSO4·7H2O was prepared according to 40 g / L Fe 2+The concentration of the solution was added to the 9K medium and mixed well. The seed solution obtained in step (3) was inoculated at an inoculation rate of 10%. The pH was adjusted to 1.5. The reaction was stirred at 25℃ and 120 r / min. The ferrous ion content was measured. When the ferrous ion conversion rate was ≥99.5%, the microbial particles were magnetically separated and recovered. The microbial particles were mixed with a synergist aqueous solution at a volume ratio of 100:1 to obtain high-efficiency polyferric sulfate. The 9K medium consisted of the following components: ammonium sulfate 3 g / L, dipotassium hydrogen phosphate 0.5 g / L, potassium chloride 0.1 g / L, magnesium sulfate heptahydrate 0.5 g / L, calcium nitrate 0.01 g / L, and the remainder was water.

[0032] Example 3: A method for producing high-efficiency polyferric sulfate, comprising the following steps: (1) Preparation of microbial particles: (11) Under stirring conditions, 2.8 g of FeCl3·6H2O and 0.7 g of sodium citrate were added to 100 mL of ethylene glycol and mixed thoroughly. 4.2 g of sodium acetate was added and stirred to react. The mixture was then transferred to a high-pressure reactor and reacted at 200 °C for 9 h. After natural cooling, magnetic separation was performed, and the magnetic components were collected. The mixture was washed with deionized water and ethanol and dried under vacuum to obtain Fe3O4 magnetic microspheres. (12) Mix 20 mL of deionized water and 60 mL of anhydrous ethanol, add 1 g of Fe3O4 magnetic microspheres obtained in step (11), disperse by ultrasonication for 18 min, add 1 mL of 25 wt% ammonia water dropwise while stirring, continue stirring for 30 min, add 1 mL of tetraethyl orthosilicate (TEOS) dropwise, stir and react for 24 h, collect the magnetic part by magnetic separation, wash with ethanol and deionized water, and dry under vacuum to obtain Fe3O4@SiO2; (13) Take 1 g of Fe3O4@SiO2 obtained in step (12) and 1 g of 3-aminopropyltrimethoxysilane (APTMS) and disperse them in 20 mL of ethanol by ultrasonication. Heat at 80 °C for 7 h. The magnetically separated product is washed with anhydrous ethanol and deionized water and dried under vacuum to obtain Fe3O4@SiO2-NH2. (14) Under a nitrogen atmosphere, 1 g of protocatechuic acid (PCA) was dissolved in 10 mL of ethanol to obtain a PCA solution. 1.25 g of EDC·HCl was dissolved in 62.5 mL of MES buffer solution with pH=5.5. The PCA solution was added and the reaction was stirred. Then 0.75 g of NHS was added and stirred in an ice-water bath in the dark for 1 h. 1.2 g of Fe3O4@SiO2-NH2 obtained in step (13) was added and stirred in the dark at room temperature for 24 h. The mixture was magnetically separated, washed with deionized water and ethanol, and dried under vacuum to obtain Fe3O4@SiO2-PCA. (15) Dissolve 6 g of mercaptopolyethylene glycol carboxyl group in 150 mL of 10 mM pH 8.5 tris-HCl buffer solution, add 1 g of Fe3O4@SiO2-PCA obtained in step (14) under stirring at 1200 rpm, stir for 1 h, purify by magnetic separation, wash with deionized water, and dry under vacuum to obtain Fe3O4@SiO2-SH-PEG-COOH; (16) Take the logarithmic growth phase of *Acidithiobacillus ferrooxidans*, wash with 0.01 M sulfate buffer at pH 2.5, and resuspend in PBS buffer at pH 5 to obtain a concentration of 5 × 10⁻⁶. 8 CFU / mL bacterial suspension, Fe3O4@SiO2-SH-PEG-COOH 0.5 g obtained in step (15) was dispersed in 500 mL of PBS buffer at pH 5, EDC·HCl 5 g was added, stirred for 10 min, NHS 3 g was added and stirred for 30 min, added to 250 mL of bacterial suspension, reacted at 30℃ for 4-6 h, magnetically separated, washed, and microbial particles were obtained; (2) Preparation of synergists: (21) Take 1 g of gallic acid (GA) and add it to 100 mL of deionized water. Purge with nitrogen gas and stir at 50 °C to dissolve. Adjust the pH of the solution to 12 with 20 wt% NaOH solution. Heat to 80 °C and add 65 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride solution dropwise. The mass ratio of gallic acid to 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1:4. Maintain the pH of the solution at 12 and react for 4 h. Cool to room temperature, neutralize with HCl solution, add to acetone, recrystallize the precipitate in ethanol, and dry under vacuum to obtain GA-CHMAC. (22) Dissolve 0.5 g of EDC·HCl in 100 mL of MES buffer at pH 5.5, add 1 g of GA-CHMAC obtained in step (21), stir for 10 min, add 0.3 g of NHS, stir for 1 h, add 2 g of polylysine, stir for 12 h, dialyze in deionized water for 24 h, freeze dry to obtain the synergist; (3) FeSO4·7H2O was prepared according to 9 g / L Fe 2+ The concentration of [amount] was added to 9K medium and mixed thoroughly to obtain a mixed nutrient solution. Microbial particles were then inoculated into the mixed nutrient solution at a cell density of 2 × 10⁻⁶. 8 cfu / mL, adjust pH to 1.8, stir at 28℃ and 120 rpm, when Fe 2+ When the conversion rate reaches 85%, the solution is inoculated into freshly prepared mixed nutrient solution at an inoculum volume of 10%. 2+ The concentration is gradually increased, and the process is continuously acclimatized until the reaction cycle stabilizes, resulting in seed liquid. (4) FeSO4·7H2O was prepared according to 40 g / L Fe 2+ The concentration of the solution was added to the 9K medium and mixed well. The seed solution obtained in step (3) was inoculated at an inoculation rate of 10%. The pH was adjusted to 1.8. The reaction was stirred at 28℃ and 120 r / min. The content of ferrous ions was measured. When the ferrous ion conversion rate was ≥99.5%, the microbial particles were magnetically separated and recovered. The microbial particles were mixed with a synergist aqueous solution at a volume ratio of 100:1 to obtain high-efficiency polyferric sulfate. The 9K medium consisted of the following components: ammonium sulfate 3 g / L, dipotassium hydrogen phosphate 0.5 g / L, potassium chloride 0.1 g / L, magnesium sulfate heptahydrate 0.5 g / L, calcium nitrate 0.01 g / L, and the remainder was water.

[0033] The only difference between Comparative Example 1 and Example 1 is that 1.5 g of Fe3O4@SiO2-NH2 was dispersed in DMF, 2 g of succinic anhydride was added, oxygen was purged with argon, 0.4 mL of triethylamine was added, the mixture was ultrasonically mixed, mechanically stirred at 110°C for 12 h, magnetically separated, washed with DMF and anhydrous ethanol, and vacuum dried to obtain Fe3O4@SiO2-COOH. The obtained product was used to replace Fe3O4@SiO2-SH-PEG-COOH.

[0034] The only difference between Comparative Example 2 and Example 1 is that the logarithmic growth phase of *Thiobacillus ferrooxidans* was used instead of the microbial particles.

[0035] The only difference between Comparative Example 3 and Example 1 is that polylysine is used instead of the synergist.

[0036] The only difference between Comparative Example 4 and Example 1 is that no synergist was added.

[0037] Experimental Example 1: A sample of urban wastewater with high chemical oxygen demand (COD) (360 mg / L) was taken. High-efficiency polyferric sulfate prepared in Examples 1-3 and Comparative Examples 3-4 was added to the wastewater at a dosage of 2‰. The pH was adjusted to 7, and the mixture was stirred at 50 r / min for 10 min, allowed to stand for 30 min, and the COD of the supernatant was measured. The wastewater COD removal rate results are as follows: Figure 1 As shown.

[0038] Figure 1 The results showed that the COD removal rate of wastewater in Examples 1-3 was significantly better than that in Comparative Examples 3-4. In Comparative Example 3, the flocculation effect decreased when polylysine was used to replace the synergist, and in Comparative Example 2, no synergist was added, resulting in a decrease in flocculation effect and a reduction in the removal rate of organic matter in wastewater.

[0039] Experimental Example 2: Following the method of Experimental Example 1, the high-efficiency polyferric sulfate obtained in Examples 1-3 and Comparative Examples 3-4 was added to wastewater, and the antibacterial rates against Escherichia coli and Staphylococcus aureus were tested. The results are as follows: Figure 2 As shown.

[0040] Figure 2 The results showed that both the Examples 1-3 and the Comparative Examples 3-4 had high antibacterial rates. The antibacterial rate of Examples 1-3 was higher than that of Comparative Examples 3-4. The antibacterial effect of Comparative Example 3 decreased when polylysine was used to replace the synergist, and the antibacterial rate of Comparative Example 4 decreased when no synergist was added.

[0041] Experimental Example 3: Following the methods of Example 1 and Comparative Examples 1-2, high-efficiency polyferric sulfate was prepared, and the Fe content at different times was measured and recorded. 2+ Conversion rate, results as follows Figure 3 As shown.

[0042] Figure 3 The results showed that Fe in Example 1 group 2+ The conversion rate was significantly better than that of Comparative Examples 1-2, and the oxidation rate was faster. In Comparative Example 1, replacing Fe3O4@SiO2-SH-PEG-COOH with Fe3O4@SiO2-COOH slowed down the oxidation rate. In Comparative Example 2, replacing the microbial particles with logarithmic growth-phase *Acidithiobacillus ferrooxidans*, Fe... 2+ The conversion rate slows down, and the oxidation rate decreases.

[0043] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for producing high-efficiency polyferric sulfate, characterized in that, Includes the following steps: (1) Preparation of microbial particles: (11) Add FeCl3·6H2O and sodium citrate to ethylene glycol, add sodium acetate, react, collect the magnetic components, wash, dry, and obtain Fe3O4 magnetic microspheres; (12) Mix water and ethanol, add Fe3O4 magnetic microspheres, add ammonia dropwise, stir, add TEOS, stir to react, magnetically separate, wash, dry, and obtain Fe3O4@SiO2; (13) Fe3O4@SiO2 and APTMS were dispersed in ethanol, heated, magnetically separated, washed and dried to obtain Fe3O4@SiO2-NH2; (14) Dissolve EDC·HCl in MES buffer solution, add protocatechuic acid solution, stir to react, add NHS, stir, add Fe3O4@SiO2-NH2, stir, magnetically separate, wash, dry, and obtain Fe3O4@SiO2-PCA; (15) Dissolve the carboxyl group of mercapto polyethylene glycol in tris-HCl buffer solution, stir, add Fe3O4@SiO2-PCA obtained in step (14), stir to react, magnetically separate, wash, dry, and obtain Fe3O4@SiO2-SH-PEG-COOH; (16) Take the logarithmic growth phase of Acidithiobacillus ferrooxidans, wash it with sulfuric acid buffer, resuspend it with PBS buffer to obtain a bacterial suspension, disperse Fe3O4@SiO2-SH-PEG-COOH in PBS buffer, add EDC·HCl, stir, add NHS, add to the bacterial suspension, react, magnetically separate, wash, and obtain microbial particles; (2) Preparation of synergists: (21) Add gallic acid to deionized water, purge with nitrogen, stir to dissolve, adjust pH, heat, add 3-chloro-2-hydroxypropyltrimethylammonium chloride solution dropwise, react to obtain GA-CHMAC; (22) Dissolve EDC·HCl in MES buffer, add GA-CHMAC, stir, add NHS, stir, add polylysine, stir to react, dialyze, freeze dry to obtain synergist; (3) Add FeSO4·7H2O to 9K medium and mix well to obtain a mixed nutrient solution. Inoculate microbial particles into the mixed nutrient solution and determine the Fe content. 2+ Conversion rate: The solution is inoculated into a mixed nutrient solution and continuously acclimatized to obtain seed solution; (4) Add FeSO4·7H2O to 9K medium and mix well. Inoculate the seed liquid obtained in step (3), measure the ferrous ion conversion rate, mix with the synergist, and obtain high-efficiency polyferric sulfate.

2. The method for producing high-efficiency polyferric sulfate according to claim 1, characterized in that, In step (11), the mass ratio of FeCl3·6H2O, sodium citrate and sodium acetate is 4:1:

6.

3. The method for producing high-efficiency polyferric sulfate according to claim 2, characterized in that, In step (12), the ratio of TEOS to Fe3O4 magnetic microspheres is 1 mL:1 g.

4. The method for producing high-efficiency polyferric sulfate according to claim 3, characterized in that, In step (13), the mass ratio of Fe3O4@SiO2 to APTMS is 1:

1.

5. The efficient method for producing polyferric sulfate according to claim 4, characterized in that, In step (14), the mass ratio of protocatechuic acid to Fe3O4@SiO2-NH2 is 1:1-1.5; the mass ratio of protocatechuic acid, EDC·HCl and NHS is 0.4:0.5:0.

3.

6. The method for producing high-efficiency polyferric sulfate according to claim 5, characterized in that, In step (15), the mass ratio of the mercapto polyethylene glycol carboxyl group to Fe3O4@SiO2-PCA is 6:

1.

7. The method for producing high-efficiency polyferric sulfate according to claim 6, characterized in that, In step (21), the mass ratio of gallic acid to 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1:

4.

8. The method for producing high-efficiency polyferric sulfate according to claim 7, characterized in that, In step (22), the mass ratio of GA-CHMAC to polylysine is 1:2.

Images