Abstract
In this study, the high-gravity technique is used to intensify the heterogeneous catalytic ozonation with activated carbon (AC) as the catalyst for removal of phenol from wastewater in a rotating packed bed (RPB), and the effects of high-gravity factor, inlet O3 concentration, liquid-gas ratio and initial pH on the degradation and mineralization of phenol at room temperature are investigated. It is revealed that the degradation rate of phenol reaches 100% at 10 min and the removal rate of total organic carbon (TOC) reaches 91% at 40 min under the conditions of high-gravity factor β=40, inlet O3 concentration =90 mg·L-1, liquid flow rate =80 L·h-1 and initial pH=11. Compared with the bubbling reactor (BR)/O3/AC and RPB/O3 systems, the mineralization rate of phenol by the RPB/O3/AC system is increased by 24.78% and 34.77%, respectively. Free radical quenching experiments are performed using tertiary butanol (TBA) and benzoquinone(BQ) as scavengers of ·OH and O2·−, respectively. It is shown that the degradation and mineralization of phenol are respectively attributed to the direct ozonation and the indirect oxidation by ·OH generated from the decomposition of O3 adsorbed on AC surface. •OH and O2•− are also detected by electron paramagnetic resonance (EPR). Thus, it is concluded that AC-catalyzed ozonation and high gravity technique had a synergistic effect on •OH initiation, which in turn can significantly improve the degradation and mineralization of organic wastewater.
Combined photolysis and catalytic ozonation of dimethyl phthalate in a high-gravity rotating packed bed
