Kinetic evaluation of graphene oxide based heterogenous catalytic ozonation for the removal of ibuprofen

Abstract

In this study, the performance of graphene oxide (GO) in ozonation process was kinetically evaluated using the modified Rct concept since GO may act as initiator, promoter and inhibitor in ozone radical chain reaction. The applicability of the modified Rct concept was demonstrated using different GO suspensions (GO alone, GO/TiO2, GO/Fe3O4, GO/TiO2/Fe3O4) in ozonation process. Results showed that ozone exposure and •OH exposure were found to be higher for GO/Fe3O4 and GO/TiO2/Fe3O4 compared to other GO suspensions, which was almost equivalent to O3/H2O2 process. The determined initiation and inhibition rate constants of GO alone, were 1 fold higher than GO/Fe3O4 and GO/TiO2/Fe3O4, since the GO alone suspension possesses higher O3 decomposition but lower organic degradation because that GO does not yield •OH. Moreover, GO/Fe3O4 suspension, along with natural organic matter (NOM), was proven to be helpful in degrading ibuprofen in ozonation process, but the effect was minimal when compared to O3/H2O2 process. These results exhibited that the surface modified GO suspensions could be utilized as future alternative AOPs.