Colloidal properties and stability of UV-transformed graphene oxide in aqueous solutions: The role of disorder degree

Abstract Motivated by the use of ultraviolet (UV) radiation in the disinfection processes of drinking and waste water treatment plants, this study explores the colloidal properties and stability of UV irradiated graphene oxide (GO) by using the batch technique and time-resolved dynamic light scattering over a wide range of salt types (NaCl, MgCl2, and CaCl2) and ionic strength relevant to engineered and natural systems. The results show that the UV irradiation time has an important impact on the physicochemical properties of GO and consequently on its colloidal properties and stability. The aggregation kinetics, attachment efficiency and critical coagulation concentration (CCC) values of UV irradiated GO are obtained for the first time. By correlating CCC values with physicochemical properties, we find that the disorder degree plays a more important role in colloidal properties and stability of UV irradiated GO than oxygen containing functional groups. The findings are valuable for environmental fate assessments on various families of functionalized GO.