CHEMICAL SCIENCE

A novel photocatalytic and advanced oxidation coupling organic sewage treatment technology


The cover image was produced by the Science Visualization Center of China Science Newspaper

Recently, Sun Chenglin, researcher sun Chenglin and wei Huangcao, researchers of the Department of Energy Conservation and Environment Research of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, cooperated with Li Rengui, researcher of the State Key Laboratory of Catalysis Foundations, etc., to develop a new type of photocatalytic water oxidation and traditional catalytic hydrogen peroxide wet oxidation (CWPO) coupling technology, to achieve efficient removal of organic pollutants, and apply it to industrial organic wastewater treatment.

On August 22, 2022, the study was published in Applied under the title “Coupling Photocatalytic Water Oxidation on Decahedron BiVO4 Crystals with Catalytic Wet Peroxide Oxidation for Removing Organic Pollutions in Wastewater.” Catalysis B: Environmental journal. The first authors of the work are Zhao Yue, a postdoctoral fellow at the Dalian Institute of Chemicals, and Wang Yijing, a master’s student.

Discharging organic compounds directly into the water without treatment can cause harm to the environment. CWPO is an advanced oxidation technique that uses hydrogen peroxide as an oxidant to catalyze the decomposition of hydrogen peroxide into more oxidizing hydroxyl radicals (· OH), which in turn oxidizes organic pollutants into small molecule organic matter, or even directly mineralizes organic matter. CWPO technology can react at room temperature and pressure, and has the characteristics of simple operation, economy and environmental protection, and has received wide attention in the field of refractory biodegradable organic wastewater treatment at low and medium concentrations. However, the technology has problems such as low utilization rate of oxidant H2O2 and difficult circulation of iron ions, which makes the system cost and indirect energy consumption higher, limiting its further large-scale application.

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This work was influenced by the “hydrogen farm” strategy proposed by the team of academician Li Can in the early stage (Angew. Chem. Int. Ed.,2020;Angew. Chem. Int. Ed., 2022) and intercrystalline surface photogenerated charge separation characteristics (Nature Commun., 2013; Energy Environ. Sci., 2014) work, proposed photocatalytic water oxidation and CWPO coupling technology (Photo-CWPO), the use of photogenerated electrons to achieve the reduction of Fe3+ to Fe2+, so as to achieve efficient cycling of iron ions in CWPO; At the same time, the oxidative degradation of organic pollutants is achieved by using photogenerated holes, which greatly reduces the use of the coupling system H2O2. It was found that the decahedral BiVO4 photocatalyst was introduced and coupled with CWPO, benefiting from the efficient charge separation efficiency of the scapahedral BiVO4 photocatalyst and the efficient irreversibility of Fe3+ to Fe2+, the Photo-CWPO system showed much higher molecular degradation efficiency of organic pollutants than the CWPO system alone, effectively reducing the use of Fe2+ and the emission of iron sludge. In addition, this study also found that H2O2 can be generated in situ by the two-electron water oxidation process on the surface of BiVO4, and then reacted with Fe2+ in the system. OH, used in the molecular degradation of organic pollutants, further reduces the use of H2O2 in the entire system, thereby reducing the cost of treatment. The Photo-CWPO strategy has been verified in the degradation of more than ten organic pollutant molecules, showing good universality and stability. The proposed and verification of this strategy provides a new efficient and low-cost technical route for the deep mineralization of organic wastewater.

Based on this research work, Photo-CWPO technology has been amplified and applied in the actual industrial wastewater treatment, and has been applied to the treatment of coal chemical wastewater, methanol to olefin wastewater, meta-metformine wastewater, etc., showing good treatment effect. At present, the technology is in the pilot phase.

The above work has been funded by the Innovation Fund of Dalian Institute of Chemicals, the National Key Research and Development Program, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and the National Natural Science Foundation of China. (Source: Science Network)

Related paper information:https://doi.org/10.1016/j.apcatb.2022.121858



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