The potential of graphene-based materials, including graphene oxide (GO), over-oxidized graphene oxide (oGO), and non-oxidized graphene (nOG), for catalytic ozonation was investigated, along with the mechanism of ozone catalysis. Increasing the extent of oxidation of graphene led to the formation of hydroxyl and carboxyl groups on the graphene surface, which then partially converted into epoxy groups. The catalytic efficiency of oGO was much higher than that of both GO and nOG. Graphene's extent of oxidation might be a significant factor in catalytic ozonation. The hydroxyl radical exposure to ozone exposure ratio (Rct) of 25 mg L-1 ozone/oGO was 75-fold higher than that of an ozone alone process. The ozone decomposition rate and para-chlorobenzoic acid removal efficiency were higher at pH 9 than at any other pH. The Rct of ozone/oGO at pH 9 was 2.35 × 10-5. Temperature affected ozone adsorption on the nOG surface. Ozone/graphene experiment with an excess of tert-butyl alcohol was proposed that hydroxyl radicals generated by GO and oGO existed mainly in the solution phase, while those generated by nOG existed in both solution and surface phases.
Bibliographical noteFunding Information:
This work is supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (2016R1A2B4015598), and Korea Ministry of Environment (MOE) as A real scale project on algae monitoring and removal-utilization technology (2015001800001), and the Ministry of Trade, Industry and Energy through Technology Innovation Program (Grant No. 10067449).
All Science Journal Classification (ASJC) codes
- Chemical Engineering (miscellaneous)
- Waste Management and Disposal
- Process Chemistry and Technology