Photobiosynthesis of metal/graphene nanocomposites: new materials for water desalination and purification

Ultra-pure water, free from metals and micro-organisms, has been easy obtained from Red seawater (Jeddah, KSA) by plasmonic-graphene hybrid nanocomposites that green synthesized using Baker's yeast (Saccharomyces cerevisiae) extract under visible light irradiation. Gas chromatography mass spectroscopy (GC/MS) analysis of aqueous yeast extract indicates the presence of significant biomolecules; butane-2,3-diol, glucose, undecanoic acid, and indole-3-acetic acid that can act under visible light as reducing and capping agent for the growth of (Ag, Au, and Ag/Au) plasmonic nanoparticles and graphene-based plasmonic nanocomposites. These nanocomposites able to absorb sunlight very strongly and converting it very efficiently into heat energy that enhancing the seawater evaporation. Bimetallic Ag/Au/reduced graphene-oxide nanocomposites show the highest gain of temperature and highest stability after three times of recycling processes. These eco-friendly nanocomposites are smart alternatives in water desalination and purification technique by taking the advantages of their excellent photothermal conversion, its energy-saving, cost-effective, and ease recyclability.