A deep treatment method for pharmaceutical wastewater based on peroxide removal of residual drugs mediated by interfacial electron migration of immobilized materials.

Abstract

This invention discloses a method for deep treatment of pharmaceutical wastewater based on peroxide removal mediated by interfacial electron migration of immobilized materials. Using porous, highly stable, and mechanically strong SiC foam as a carrier, highly active components such as CuBi₂O₄, CuCo₂O₄, Cu / MnO₂, and Fe / C₃N₄ are loaded in situ and with high dispersion at the interface. This effectively solves the problems of easy agglomeration, difficulty in separation, and low recovery efficiency of powdered active ingredients. By adding hydroxylamine hydrochloride and ascorbic acid to enhance interfacial electron transfer of active ingredients, the method addresses the issues of slow reduction rates of high-valence metal ions and difficulty in regenerating free electrons. This achieves efficient activation of hydrogen peroxide, monopersulfate, persulfate, and ozone, mediating the generation of highly oxidizing hydroxyl radicals, sulfate radicals, superoxide anion radicals, and singlet oxygen, thus realizing the efficient oxidation of recalcitrant organic matter in drinking water and wastewater.

Description

Technical Field

[0001] This invention relates to a method for advanced treatment of pharmaceutical wastewater based on electron migration-mediated removal of residual drugs by peroxides at the interface of immobilized materials, belonging to the field of water pollution control engineering. Background Technology

[0002] In recent years, with the rapid development of the pharmaceutical industry, environmental problems caused by pharmaceutical wastewater have become increasingly prominent. Pharmaceutical wastewater is characterized by complex and highly toxic pollutants, and the residual drugs within it are persistent and have long half-lives, making them difficult to effectively degrade. This presents new challenges to the development of wastewater treatment technologies. Currently, treatment technologies for removing residual drugs mainly include physical, biological, and chemical methods, but these traditional methods are unlikely to achieve the desired degradation effects. Advanced oxidation technologies utilize highly reactive species generated by strong oxidants to oxidize and decompose recalcitrant organic matter in wastewater into low-molecular-weight substances or even completely mineralize it into carbon dioxide and water.

[0003] Transition metals and their oxides effectively enhance the activation of peroxides and the removal of organic matter through mechanisms such as providing active sites, adsorbing organic molecules, and participating in electron transfer. However, the leakage of metal ions during the reaction process inevitably causes secondary pollution.

[0004] Immobilizing metal ions on a support can effectively suppress metal ion leakage. Patent CN116603527A prepared a biochar-supported iron-cobalt bimetallic oxide catalyst through co-precipitation-high-temperature pyrolysis. The abundant functional groups on the biochar surface can effectively adsorb iron and cobalt ions, preventing metal ion aggregation during calcination and promoting metal ion loading on the biochar surface. The resulting material has a high specific surface area, abundant active sites, and excellent persulfate activation performance. Patent CN110961159B used ZIF-67 as a template to co-precipitate iron and cobalt onto ZIF-67, obtaining a magnetic Fe-Co / ZIF-6 bimetallic catalyst through calcination. This catalyst exhibits good catalytic performance and high reusability in the process of activating persulfate to degrade dyes. However, most current metal immobilization materials are nanoparticles, which have drawbacks such as small size, easy aggregation, limited exposure of metal active sites, difficulty in separation, and poor support mechanical stability.

[0005] Foamed silicon carbide (SiC) is a novel inorganic non-metallic porous bulk material with advantages such as a unique three-dimensional network framework, high porosity, high temperature resistance, corrosion resistance, high mechanical strength, and stable chemical structure. Using it as a support for metal ions holds promise for synthesizing structurally stable, pore-rich, and widely adaptable bulk catalysts. Patent CN 111729678 A describes the preparation of mesoporous silicon carbide material using mesoporous silica as a hard template. This material is then mixed with a precursor solution of palladium and copper, and after drying, calcination, and reduction, a palladium-copper-supported mesoporous silicon carbide-based catalyst is obtained, which is applied to the electrocatalytic denitrification reaction of nitrates. Mesoporous silicon carbide can stably disperse palladium and copper in the mesoporous channels, preventing the aggregation of the palladium-copper active components and providing more active sites, thereby improving the catalytic denitrification activity of palladium-copper. Furthermore, mesoporous silicon carbide has a high electronic band gap, enabling autocatalytic water electrolysis to produce hydrogen, which can promote the denitrification reaction. This results in the superior catalytic effect of the palladium-copper supported mesoporous silicon carbide-based catalyst prepared in this invention compared to other palladium-copper supported catalysts. Patent CN 115106106B utilizes an electrophoretic pulse method to process graphene-supported silicon carbide photocatalysts. Silicon carbide itself possesses a suitable bandgap and sensitive photosensitivity, making it an excellent photocatalytic support. When combined with graphene to form a heterojunction, the interface effect of the heterojunction can suppress carrier migration and recombination, further improving its photocatalytic hydrogen production efficiency. Patent 112892569A obtains cerium oxide-supported silicon carbide catalysts with varying contents through wet impregnation and dry calcination, and applies these catalysts to the selective oxidation of hydrogen sulfide to sulfur under medium- and high-temperature conditions. The nano-silicon carbide support has a large specific surface area and excellent thermal conductivity, avoiding the formation of local hot spots on the catalyst surface and improving the high-temperature stability of the material. Cerium oxide is a good oxygen storage and release material and also exhibits high catalytic activity for the selective oxidation of hydrogen sulfide at high temperatures. Loading cerium oxide onto the nano-silicon carbide support further improves the catalytic stability of the material. Currently, silicon carbide supported catalysts are mainly used in electrocatalysis, photocatalysis and high-temperature synthesis, but there are no reports on their use as catalyst supports for activating persulfate treatment technology.

[0006] A key reason for the slowed degradation of organic matter in peroxide-activated metal oxide catalyst systems is the inability to effectively reduce high-valence metal ions to low-valence metal ions during the reaction. Studies have shown that adding reducing agents to the system enhances the efficiency of iron-activated peroxide degradation of organic matter. Therefore, selecting an effective reducing agent can reduce the high-valence metals involved in the reaction to low-valence metals, thereby improving the performance of metal-activated persulfate in degrading pollutants.

[0007] Therefore, this patent constructs a water purification method based on enhanced interfacial electron migration mediated by peroxides to remove recalcitrant organic matter by loading a catalyst onto the surface of foamed SiC and introducing a green and safe reducing agent. This is an environmentally friendly water treatment technology. Summary of the Invention

[0008] This invention proposes a method for deep treatment of pharmaceutical wastewater based on electron migration at the interface of immobilized materials to remove residual drugs using peroxides. Using porous, highly stable, and mechanically strong SiC foam as a carrier, highly active components such as CuBi₂O₄, CuCo₂O₄, Cu / MnO₂, and Fe / C₃N₄ are loaded in situ and with high dispersion at the interface. This effectively solves the problems of easy agglomeration, difficulty in separation, and low recovery efficiency of powdered active ingredients. By adding hydroxylamine hydrochloride and ascorbic acid to enhance the electron transfer at the interface of active ingredients, the method addresses the problems of slow reduction rates of high-valence metal ions and difficulty in regenerating free electrons. This achieves efficient activation of hydrogen peroxide, monopersulfate, persulfate, and ozone, mediating the generation of oxidizing hydroxyl radicals, sulfate radicals, superoxide anion radicals, and singlet oxygen, thus realizing the efficient oxidation of recalcitrant organic matter in drinking water and wastewater.

[0009] This invention provides a method for advanced treatment of pharmaceutical wastewater based on electron migration-mediated peroxide removal of residual drugs at the interface of immobilized materials. The method is characterized by: (i) obtaining the SiC foam-supported catalyst material through the following steps: (1) ultrasonically cleaning the SiC foam support in anhydrous ethanol for 10 min, then ultrasonically cleaning it again in deionized water for 10 min, and drying it at 70°C for later use; (2) adding 9 mmol Cu(NO3)2·3H2O and 18 mmol Bi(NO3)3·5H2O to 60 mL of 10%... In HNO3, stir until dissolved at room temperature, put in the cleaned SiC foam carrier, add 150 mL of 2.0 mol / L NaOH solution dropwise, and stir magnetically while adding. Put in a microwave reactor and react at room temperature for 0.5 h under 150 W power. Wash repeatedly with deionized water to obtain the product. When the washing water is stable to neutral conditions, dry in an environment of 70 °C for 8 hours to obtain SiC foam loaded CuBi2O4; (3) Dissolve a certain amount of hexadecyltrimethylammonium bromide (CTAB) in 70.0 mL of deionized water. Dissolve 1.0 mmol Cu(NO3)2·3H2O and 2.0 mmol Co(NO3)2·6H2O in the above solution, then add 5.0 mmol urea, put in the cleaned SiC foam support, stir the mixed solution for 1 h, then transfer it to a 100 mL polytetrafluoroethylene-lined autoclave, and carry out a hydrothermal reaction in an oven at 120 °C for 12 h. After cooling to room temperature, collect the SiC foam support, wash with deionized water and anhydrous ethanol, dry at 60 °C for 8 h, and calcine the SiC foam support loaded with the precursor at 500 °C for 3 h with a heating rate of 2 °C / min to obtain SiC foam loaded with CuCo2O4; (4) Add 30.0 mmol potassium permanganate and 7.5 mmol CuSO4·5H2O was dissolved in 50mL of deionized water. A 200mmol / L maleic acid solution was prepared using deionized water. The cleaned SiC foam support was placed in a mixed solution of potassium permanganate and copper sulfate. Maleic acid solution was added dropwise and stirred for 1h. The mixture was aged at room temperature for 24h to complete the redox reaction. The loaded SiC foam support was washed with deionized water until the conductivity of the supernatant was constant. After drying at 70℃ overnight, it was calcined in air at 300℃ for 1h to obtain SiC foam loaded with Cu / MnO2. (5) 10g of urea was placed in an agate mortar and ground thoroughly. The ground powder was transferred to a 50mL ceramic crucible and calcined in a muffle furnace at 550℃ for 4h with a heating rate of 2℃ / min. After calcination, the mixture was cooled to room temperature and ground thoroughly to obtain a light yellow g-C3N4 powder for later use.0.674 g FeCl3·6H2O, 0.453 g 2-aminoterephthalic acid, and 56.0 mL N,N-dimethylformamide (DMF) were stirred at room temperature until the solution became transparent. The solution was then placed in a cleaned SiC foam support, followed by the addition of a certain amount of g-C3N4 and ultrasonic dispersion for 30 min. The dispersed mixture was transferred to a 100 mL polytetrafluoroethylene reaction vessel liner. The container was sealed in a stainless steel shell, placed in an oven, heated to 170 °C, and maintained at this temperature for 24 h. Finally, it was allowed to cool naturally to obtain SiC foam-supported crystals. The crystals were washed three times with DMF solution and anhydrous ethanol, centrifuged, and then dried at 100 °C in a vacuum environment to obtain the precursor (NH2-MIL-53(Fe) / g-C3N4). The dried precursor was transferred to a quartz boat and pyrolyzed in a tube furnace under a nitrogen atmosphere at 650 °C. The heating rate was 5 °C / min, and the temperature was maintained for 3 h. The nitrogen flow rate was 300 ± 5 mL / min. After pyrolysis, the mixture was cooled to room temperature to obtain SiC foam-supported Fe / C3N4.

[0010] The method for removing recalcitrant organic matter by peroxides based on enhanced interfacial electron migration-mediated water purification is characterized by the following steps for wastewater treatment: (1) The concentration of hydroxylamine hydrochloride is 0.65–5.0 mmol / L; (2) The concentrations of hydrogen peroxide, persulfate monosulfate, persulfate disulfate, and ozone are 0.325–1.3 mmol / L; (3) The residence time is 30–120 min; (4) The salinity of the wastewater is 0–12000 mg / L; (5) The total dissolved solids in the wastewater are 0–40.0 g / L; (6) The concentration of organic pollutants in the water to be treated is 2.0–20.0 mg / L.

[0011] The superior effects of this invention are as follows: This invention provides a deep treatment method for pharmaceutical wastewater based on electron migration at the interface of immobilized materials to remove residual drugs using peroxides. It utilizes porous, highly stable, and mechanically strong SiC foam as a carrier, and in situ, highly dispersed loading of highly active components such as CuBi₂O₄, CuCo₂O₄, Cu / MnO₂, and Fe / C₃N₄ at the interface. This effectively solves the problems of easy agglomeration, difficulty in separation, and low recovery efficiency of powdered active ingredients. By adding hydroxylamine hydrochloride and ascorbic acid to enhance the electron transfer at the interface of active ingredients, it solves the problems of slow reduction rate of high-valence metal ions and difficulty in regenerating free electrons. This achieves efficient activation of hydrogen peroxide, monopersulfate, persulfate, and ozone, mediating the generation of highly oxidizing hydroxyl radicals, sulfate radicals, superoxide anion radicals, and singlet oxygen, thus realizing efficient oxidation of recalcitrant organic matter in drinking water and wastewater. Attached Figure Description

[0012] Figure 1The image shows the XRD pattern of the CuBi2O4 / SiC material prepared in this invention.

[0013] Figure 2 The graph shows the degradation effect of CuBi2O4 / SiC material prepared in this invention on activated persulfate and the recalcitrant pollutant benzophenone-4 (BP-4).

[0014] Figure 3 The graph shows the degradation effect of CuBi2O4 / SiC material prepared in this invention on the recalcitrant pollutant benzophenone-4 (BP-4) after different number of uses of activated persulfate.

[0015] Figure 4 The graph shows the degradation effect of the CuBi2O4 catalyst prepared in this invention on the recalcitrant pesticide chlorpyrifos in the presence of the reducing agents ascorbic acid (AA) and hydroxylamine hydrochloride (HA). Detailed Implementation

[0016] The present invention will be described in further detail with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0017] Example 1: Preparation method of SiC foam supported catalyst material

[0018] The material can be obtained through the following steps: (1) Soak the SiC foam carrier in anhydrous ethanol for 10 min, then soak it in deionized water for another 10 min, and dry it at 70°C for later use; (2) Add 9 mmol Cu(NO3)2·3H2O and 18 mmol Bi(NO3)3·5H2O to 60 mL of 10% HNO3, stir at room temperature until dissolved, put the cleaned SiC foam carrier in, add 150 mL of 2.0 mol / L NaOH solution dropwise while stirring magnetically, put it in a microwave reactor and react at room temperature for 0.5 h under 150 W power, wash repeatedly with deionized water to obtain the product, until the washing water is stable under neutral conditions, and dry it at 70°C for 8 hours to obtain SiC foam-loaded CuBi2O4; (3) Dissolve a certain amount of hexadecyltrimethylammonium bromide (CTAB) in 70.0 mL of deionized water. Dissolve 1.0 mmol Cu(NO3)2·3H2O and 2.0 mmol Co(NO3)2·6H2O in the above solution, then add 5.0 mmol urea, put in the cleaned SiC foam support, stir the mixed solution for 1 h, then transfer it to a 100 mL polytetrafluoroethylene-lined autoclave, and carry out a hydrothermal reaction in an oven at 120 °C for 12 h. After cooling to room temperature, collect the SiC foam support, wash with deionized water and anhydrous ethanol, dry at 60 °C for 8 h, and calcine the SiC foam support loaded with the precursor at 500 °C for 3 h with a heating rate of 2 °C / min to obtain SiC foam loaded with CuCo2O4; (4) Add 30.0 mmol potassium permanganate and 7.5 mmol CuSO4·5H2O was dissolved in 50mL of deionized water. A 200mmol / L maleic acid solution was prepared using deionized water. The cleaned SiC foam support was placed in a mixed solution of potassium permanganate and copper sulfate. Maleic acid solution was added dropwise and stirred for 1h. The mixture was aged at room temperature for 24h to complete the redox reaction. The loaded SiC foam support was washed with deionized water until the conductivity of the supernatant was constant. After drying at 70℃ overnight, it was calcined in air at 300℃ for 1h to obtain SiC foam loaded with Cu / MnO2. (5) 10g of urea was placed in an agate mortar and ground thoroughly. The ground powder was transferred to a 50mL ceramic crucible and calcined in a muffle furnace at 550℃ for 4h with a heating rate of 2℃ / min. After calcination, the mixture was cooled to room temperature and ground thoroughly to obtain a light yellow g-C3N4 powder for later use.0.674 g FeCl3·6H2O, 0.453 g 2-aminoterephthalic acid, and 56.0 mL N,N-dimethylformamide (DMF) were stirred at room temperature until the solution became transparent. The solution was then placed into a cleaned SiC foam support. A certain amount of g-C3N4 was added and ultrasonically dispersed for 30 min. The dispersed mixture was transferred to a 100 mL polytetrafluoroethylene reaction vessel liner. The container was sealed in a stainless steel shell, placed in an oven, heated to 170 °C, and kept at this temperature for 24 h. Finally, it was naturally cooled to obtain SiC foam-supported crystals. The crystals were washed three times with DMF solution and anhydrous ethanol, centrifuged, and then dried at 100 °C in a vacuum environment to obtain the precursor (NH2-MIL-53(Fe) / g-C3N4). The dried precursor was transferred to a quartz boat and pyrolyzed in a tube furnace under a nitrogen atmosphere at 650 °C. The heating rate was 5 °C / min, and the temperature was maintained for 3 h. The nitrogen flow rate was 300 ± 5 mL / min. After pyrolysis, the mixture was cooled to room temperature to obtain SiC foam-supported Fe / C3N4.

[0019] Depend on Figure 1 It can be seen that this method successfully prepared SiC foam-supported CuBi2O4 (CuBi2O4 / SiC), which is beneficial for catalyst recovery and reuse. Figure 2 It can be seen that the metal salt solution has the best performance in degrading pollutant BP-4 when the concentration is 12.5 mmol / L.

[0020] Example 2: SiC foam-supported catalyst material for treating high-salinity wastewater

[0021] The process is achieved through the following steps: (1) The concentration of hydroxylamine hydrochloride is 1.0 mmol / L; (2) The concentrations of hydrogen peroxide, persulfate monosulfate and persulfate disulfate are 0.65 mmol / L; (3) The residence time is 60 min; (4) The salinity of the high-salt wastewater is 7100 mg / L; (5) The total dissolved solids of the high-salt wastewater is 7.1 g / L; (6) The concentration of organic pollutants in the water to be treated is 10.0 mg / L; (7) The pH range of the reaction system is 5.

[0022] Depend on Figure 4 It can be seen that when the strong reducing agent hydroxylamine hydrochloride is added to the reaction solution, the degradation rate of pymetrozine increases from 15.92% to 90.23%, and hydroxylamine hydrochloride enhances the Cu(Ⅰ) / Cu(Ⅱ) cycle on the surface of CuBi2O4 catalyst.

[0023] Example 3: Application of SiC foam-supported catalyst material-activated peroxide water treatment technology in integrated drinking water purification and disinfection.

[0024] This invention can be applied to the integrated purification and disinfection of rural drinking water. It employs a "coagulation + sedimentation filtration + chemical oxidation + disinfection" process for deep treatment of drinking water. Flocculants are added to the water source, and after thorough mixing, the water enters a flocculation tank for flocculation. The effluent from the reaction enters an inclined tube sedimentation tank, and then flows into a filter tank, where it is filtered through quartz sand media to further remove suspended solids. After turbidity treatment, a portion of the water from the filter tank is pumped into a multi-media filter filled with natural quartz sand to further remove suspended solids. This water then enters a nanofiltration water purifier to reduce dissolved solids in the raw water. The water is then pumped to a chemical oxidation tank, where the SiC foam-supported catalyst material of this invention is used. The structure is divided into 6-12 micro-units connected in series horizontally. The material replacement cycle is 24-46 hours. Hydroxylamine hydrochloride and peroxide are added during the reaction to achieve efficient deep treatment of micro-pollutants. After disinfection, the water enters a clear water tank, ultimately meeting national drinking water standards.

[0025] The specific embodiments described above are merely preferred embodiments of the present invention. However, other aspects and embodiments will be obvious to those skilled in the art. Without departing from the principle of the present invention, several modifications and improvements can be made, all of which fall within the protection scope of this application.

Claims

1. A method of preparing a SiC foam supported catalyst material, characterized by, (1) The SiC foam carrier was ultrasonically cleaned in anhydrous ethanol for 10 min, then ultrasonically cleaned in deionized water for 10 min, and dried at 70°C; (2) 9 mmol of Cu(NO3)2·3H2O and 18 mmol of Bi(NO3)3·5H2O were added to 60 mL of 10% HNO3, stirred to dissolve at room temperature, and then the cleaned SiC foam carrier was added. Then 150 mL of 2.0 mol / L NaOH solution was added dropwise while stirring, and the mixture was placed in a microwave reactor and reacted at 150 W for 0.5 h. The product was repeatedly washed with deionized water until the washing water was stable and neutral, and then dried at 70°C for 8 h to obtain the SiC foam loaded with CuBi2O4.

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