Catalytic ozonation of thymol in reverse osmosis concentratewith core/shell Fe3O4@SiO2@Yb2O3 catalyst: Parameter optimization and degradation pathway

In this work, a novel catalyst of Fe3O4@SiO2@Yb2O3 was prepared and the degradation of thymol in reverse osmosis concentrate using ozonation was explored. The operational parameters, such as ozone dosage (8-48 mg.min(-1)), initial thymol concentration (20-100 mg.L-1), initial pH value (3-11), and catalyst Fe3O4@SiO2@Yb2O3 dosage (0.2-1.0 g), were studied focusing on the thymol degradation and COD removal. The results indicated that the increase in ozone dosage, initial pH value, and Fe3O4@SiO2@Yb2O3 dosage accelerated the thymol degradation and COD removal, while the increase in initial thymol concentration hampered the effect of ozonation. A pathway of thymol degradation by catalytic ozonation was proposed based on the intermediates detected by gas chromatography-mass spectrometer and ion chromatography. This paper can provide basic data and technical alternative for pollutant removal from reverse osmosis concentrate by ozonation. (C) 2016 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.