Abstract
Rational design of nano-heterojunction catalyst is one of the ideal ways to solve dye pollution effectively. In this study, two nano-heterojunction catalysts ZnO/Ag4SiW12O40 (ZnO/AgSiW) and ZnO/Cs3PW12O40 (ZnO/CsPW), were synthesized by the simple dissolution and precipitation method. The samples were characterized by XRD, TEM, FT-IR, Raman, DRS, XPS and N2 adsorption and desorption isotherms. The photocatalytic experiments show that the degradation rates of Rhodamine B (RhB) by ZnO/AgSiW and ZnO/CsPW within 60 min are 92.3 and 72.7%, respectively, which are 5.3 and 4.2 times higher than that by pure zinc oxide. The two catalysts still maintain excellent performance after repeated use for three times. Based on the free radical capture experiment, the active substances that play a major role in the photocatalytic process were determined. In addition, the electrochemical tests show that the construction of a nano-heterojunction system significantly increases the separation efficiency of photogenerated carriers in the heterojunction system. The possible photocatalytic degradation pathways and final products of ZnO/AgSiW and ZnO/CsPW heterojunction nanocomposite catalysts were analyzed by the liquid chromatography/mass spectrometry (LC/MS) technique. This paper provides a theoretical and experimental basis for treating organic dyes by ZnO/AgSiW and ZnO/CsPW nano-heterojunction catalysts.
Highlights
IntroductionDue to the rapid development of industry, the environmental problems are becoming more and more serious
The phase structure of ZnO before and after compounding with AgSiW and CsPW was studied by X-ray diffraction (XRD)
The results show that the catalytic performance of the prepared ZnO/AgSiW and ZnO/CsPW composite catalysts is greatly improved compared with pure ZnO
Summary
Due to the rapid development of industry, the environmental problems are becoming more and more serious. Water pollution is a difficult problem among many pollution problems, and the dye wastewater produced by the textile industry is an important source of water pollution. Dyes have high molecular weight, complex structure and low biodegradability, while some dyes have carcinogenicity and mutagenicity[1, 2]. It is important to find a method to deal with dye pollution. Photocatalytic technology is considered to be a clean, efficient and promising method to deal with dye pollution. It only needs photocatalyst and ubiquitous light to deal with pollutants. It will not cause secondary pollution and is cheap[3, 4]
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