Evaluation of the O3/graphene-based materials catalytic process: pH effect and iopromide removal

Graphene-based materials, including graphene oxide (GO), reduced-graphene oxide (rGO), and non-oxidative graphene (nOG) were evaluated for catalytic ozonation in water solutions. Among the graphene-based materials evaluated for catalytic ozonation, it was confirmed that rGO was unsuitable to apply to the ozone (O3)/graphene-based materials catalytic process because the high electron mobility of rGO prevented the transformation of O3 into hydroxyl radicals (OH). On the other hand, GO, which had sufficient oxygenated functional groups on the surface, decomposed and generated the most amount of O3 and OH, respectively. Although O3/nOG process produced a lower amount of OH than O3/GO process, nOG was more effective than GO for the transformation yields of O3 into OH. Furthermore, nOG could generate OH not only in the bulk phase, but also on the surface of nOG during catalytic ozonation. However, iopromide (IPM) was effectively removed during O3/GO process due to the more OH generated in the bulk phase than O3/nOG process.