Mineralization of phenol by ozone combined with activated carbon:Performance and mechanism under different pH levels

The degradation of phenol using ozone with activated carbon(O_(3)/AC system)was investigated in this study.The O_(3)/AC system was also compared with the single O_(3) and AC systems.The total organic carbon(TOC)removal efficiency in the O_(3)/AC system was roughly 26%and 30%higher than the single AC and O_(3) systems,respectively.It was demonstrated that the phenol degradation rate and TOC removal efficiency were significantly affected by the ozone concentration,AC dosage,and solution pH.The pseudo-first-order and pseudo-second-order kinetic models were fitted to identify the mechanisms of the phenol removal process.The results of Scanning Electron Microscopy,Brunauer-Emmett-Teller,and Fourier-transform infrared spectroscopy of raw and used AC indicated that the surface morphology,microstructure,and functional group properties had been changed during the reaction process.The possible O_(3)/AC system mineralization mechanism for phenol removal was tentatively proposed using scavenging active species such as·OH,O_(2)^(·-),and H_(2)O_(2).The transformation byproducts generated during the application of the O_(3)/AC system were identified by High Performance Liquid Chromatography and Gas Chromatography-Mass Spectrometry analyses.Therefore,the mineralization pathway of phenol in detail was proposed in acidic(pH 3.0)and alkaline(pH 11.0)conditions.This study provided a more systematic explanation of the mineralization mechanism for phenol in the O_(3)/AC system.