Graphene-based nanocomposites as scavenger of heavy metal ions from water: a review on synthesis, characterizations and application as adsorbent

Graphene and graphene oxide (GO) are used for adsorbing toxic heavy metal ions, but they have disadvantages like aggregation of graphene layers due to strong π–π interactions and difficulty in separation. Thus, adsorption efficiency of bare graphene and GO is quite low. Surface modification techniques have improved GO’s adsorption capacity. Various GO-based materials, including chemically modified functionalized GO, non-metal- and metal-based GO composites, metal oxide-based GO and GO-organic compound composites, have been designed for wastewater decontamination. In this review article, the chemistry of graphene-based composites reported by various group of workers since last ten years is reviewed. The synthesis processes, characterizations of prepared materials and application as scavengers or adsorbents were critically analysed. The limitations and the future directions are also highlighted.