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 (O-3)/graphene-based materials catalytic process because the high electron mobility of rGO prevented the transformation of O-3 into hydroxyl radicals ((OH)-O-center dot). On the other hand, GO, which had sufficient oxygenated functional groups on the surface, decomposed and generated the most amount of O-3 and (OH)-O-center dot, respectively. Although O-3/nOG process produced a lower amount of (OH)-O-center dot than O-3/GO process, nOG was more effective than GO for the transformation yields of O-3 into (OH)-O-center dot. Furthermore, nOG could generate (OH)-O-center dot not only in the bulk phase, but also on the surface of nOG during catalytic ozonation. However, iopromide (IPM) was effectively removed during O-3/GO process due to the more (OH)-O-center dot generated in the bulk phase than O-3/nOG process. (C) 2016 Elsevier B.V. All rights reserved.