Biomaterial Functionalized Graphene-Magnetite Nanocomposite: A Novel Approach for Simultaneous Removal of Anionic Dyes and Heavy-Metal Ions

Despite of immense application potential of graphene in wastewater treatment, the colloidal stability, aggregation and recyclability remains a major challenge. To address this issue, we report biomaterial functionalized graphene-magnetite (Bio-GM) nanocomposite as a novel recyclable material for treatment of wastewater containing dyes and heavy metals. The integration of biomaterial including living cells of Shewanella oneidensis with graphene-magnetite nanocomposite was characterized through UV vis, FTIR, FESEM and fluorescent microscopic studies. The contact angle measurement depicted the hydrophilic property (water contact-angle 27.93 degrees), whereas VSM result demonstrated super paramagnetic behavior of the nanocomposite with saturation magnetization value of 30.2 emu/g. The Bio-GM nanocomposite exhibited excellent adsorption capacity toward dyes and Cr6+ in both single and multicomponent system with removal capacity of 189.63 +/- 7.11 and 222.2 +/- 8.64 mg/g of dyes and Cr6+, respectively, suggesting selective binding capacity and high adsorption efficiency of Bio-GM nanocomposite. In the adsorption coupled redox reaction, the Cr6+ was reduced to Cr3+ through biocatalytic activity of Bio-GM nanocomposite. The nanocomposite could be easily regenerated and reused for multiple cycles of adsorption desorption studies without release of graphene and magnetite, and thus eliminating the potential hazardous risk of nanomaterial to the environment. The proposed biomaterial functionalized graphene-magnetite nanocomposite thus offers a novel way for sustainable, affordable, and efficient removal of coexisting toxic pollutants of dyes and heavy metals.