Cellulose, graphene and graphene-cellulose composite aerogels and their application in water treatment: a review

Abstract Due to their unique properties such as outstanding specific surface areas, aerogels can potentially offer a cost-effective and efficient water and wastewater treatment solution thereby solving the worldwide ever-growing water pollution conundrum. This review explores the developments and progress in the application of cellulose, graphene, and cellulose-graphene composite aerogels in addressing water treatment challenges. The objective of this study was to critically review the state-of-the-art with respect to synthesis methods and properties of cellulose, graphene, and cellulose-graphene composite aerogels and their application, effectiveness and performance in water and wastewater treatment. It is evident from the review that cost-effective aerogel production methods that can be scaled up easily still need to be developed to enable commercial viability of aerogels in water treatment. Furthermore, the mechanical properties of aerogels, particularly stiffness and strength, are a hinderance to expanding their utility. The potential for functionalization of the aerogels through fabrication of aerogel nanocomposites or incorporation of functional groups was recognized as a viable method to enhance their properties and effectiveness in water treatment and other advanced industrial-scale applications. Graphene-cellulose composite aerogels have enhanced properties, removal capacities and efficiencies for pollutants from water compared to aerogels prepared from the individual materials. The regeneration ability and reusability of the composite aerogels make them an attractive option for practical applications. Although the potential of cellulose, graphene, and cellulose-graphene composite aerogels in water treatment applications is apparent, the impact of their production, utilization and subsequent disposal on sustainability and the environmental is yet to be fully studied.