Adsorptive removal of emerging pollutants from water using graphene-oxide and graphene oxide-based composites and its adsorption mechanisms

Emerging pollutants in the aquatic environment and their possible adverse impact on overall human and aquatic life have become an issue of concern globally. These pollutants, such as pharmaceuticals, pesticides, personal care products, food additives, wood preservatives, surfactants, plasticizers, endocrine disrupting chemicals, flame retardants, etc., are generated via anthropogenic activities. The pollutants are present in water bodies such as natural wastewater streams, and regardless of their concentrations, they pose risks to public health and aquatic animals due to accumulations resulting from short- and long-term toxicities. Besides, the traditional water treatment plants are ineffective and incapable of eliminating or degrading these contaminants. Therefore, tertiary treatment method such as adsorption has been widely adopted for removing emerging pollutants (EPs), given their low cost, efficiency, and easy operating process design. Graphene oxide (GO) has been studied as an efficient and effective adsorbent in removing EPs owing to its excellent stability (both chemical and mechanical), good hydrophilicity etc., furnished by the presence of an abundance of oxygen-rich functional groups. This chapter summarizes the applications of graphene oxide and GO-based sorbents in removing EPs from water and wastewater, pointing out the optimal conditions and factors affecting adsorption capacity. Also, the mechanism of emerging pollutants adsorption on graphene oxide is also elaborated. Solution pH and availability of multifunctional groups on the surfaces of GO and GO-based composites have been shown to be responsible for the interaction between adsorbent and contaminants. It is recommended that advanced research innovations be undertaken toward developing specific GO and GO-based adsorbents for specific target contaminants of emerging concern.