Graphene composites for water remediation: an overview of their advanced performance with focus on challenges and future prospects

The last decade has seen dramatic progress in graphene-based composites as advanced adsorbents for application in wastewater treatment. The ability to be tuned and modified as per application-based requirement especially the environmental conditions, nature of different adsorbate moieties, etc. has driven extensive research activity on graphene-based composites. Research publication has shown a spurt in reviews on the synthesis, properties, modifications and applications of such adsorbents. Still a well-defined classification of graphene-based composites and a detailed assessment on the binding affinity of various materials with graphene are missing. A clear picture regarding the advanced properties exhibited by the graphene-based composites vis-à-vis their pristine counterparts is missing. Finally, the adsorption behaviour of graphene-based composites towards a particular class of pollutants is also vague in the literature. Thus, with the aim of providing information on the interfacial surface interactions between the different class of materials with graphene-based materials, the review has presented a systematic classification of graphene-based composites and provided a comprehensive overview of the updated literature on the material properties and adsorptive performance of such classified adsorbents towards the removal of different organic and metal ion pollutants. The overview has detailed not only on the experimental parameters, adsorption behaviour, regeneration efficiency but also on the mechanistic aspects. A comparative assessment has highlighted the advancements made for the graphene-based composites. Challenges and gaps thus identified have provided a road map for future research prospects in developing a general criteria for designing graphene-based composites as per the nature and behaviour of particular class of target pollutant in aqueous medium under different conditions.