Green synthesis of reduced graphene oxide with multiple environmental applications

A sustainable and greener approach to synthesis of reduced graphene oxide (rGO) from graphene oxide (GO) was attempted using Bougainvillea Glabra (BVG) flower extract as a simple and eco-environmental friendly method. BVG flower extract exhibited antioxidant potential for FRAP/ ABTS assay [(731.53 mmol of Fe(2+)equivalents)/(56.64 mmol of Trolox equivalents)] with the anthocyanin content as 64 mg L-1. The reduction of GO to rGO was confirmed by various characterization techniques such as FTIR, Raman spectroscopy, PXRD, UV-vis absorption spectroscopy, SEM-EDS, TEM, UV-DRS, BET and ZP analysis. SEM-EDS and HR-TEM analysis revealed the stacked, smooth and layered structure of rGO with increasing atomic wt. % of carbon and reduction in oxygen as per the EDS spectra, which confirmed the successful reduction of GO. Comparative photocatalytic degradation of organic pollutants under similar experimental condition using BVG modified rGO was found to be as follows: MB (81.06%) > RhB (75.84%) > MO (57.42%) > SA (48.18%) and was higher than that of GO. Likewise, rGO exhibited higher antibacterial effect against two different Gram positive bacteria (Staphylococcus Aureus and Listeria monocytogenes) followed by two different Gram negative bacteria (Salmonella Enterica typhimurium and Escherichia coli) than GO under optimized catalyst dose (50 mg) and bacterial culture concentration (1.5 x 10(8) CFU/mL). Thus, rGO synthesized using this green approach, could be beneficial for tertiary wastewater treatment to remove the residual pollutants as well as the bacterial pathogens and can act as an effective and greener alternative over other commonly available catalyst.