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 Fe 3 O 4 @SiO 2 @Yb 2 O 3 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 Fe 3 O 4 @SiO 2 @Yb 2 O 3 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 Fe 3 O 4 @SiO 2 @Yb 2 O 3 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.