Catalytic ozonation of thymol in reverse osmosis concentrate with 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.