Ultrasound enhanced Azo Dye adsorption by Graphene Oxide Nanocomposite

Reactive azo dyes appearing in almost all streams of wastewater reportedly possess carcinogenic and mutagenic properties and are often biorecalcitrant in nature. In recent years, the process of adsorption has received much significance as one of the most efficient, easy to operate and cost effective procedures implemented for treatment of effluents containing different types of dyes. The present study was performed to investigate the potential of Graphene oxide (GO) – Zinc oxide nanoparticle (ZnO NPs) composites as an inexpensive, convenient and non-toxic adsorbent for removal of Methylene blue (MB) from solution. The ZnO NPs used in this study were synthesized in a green route from leaf extracts of basil (Ocimum sanctum). The adsorption phenomenon was catalysed by ultrasound to achieve higher rates of removal in significantly reduced time. The process was optimized using Response Surface Methodology. Under optimized conditions, 99.87% removal of upto 120 ppm dye was achieved in 6 min using only 0.75 g L-1 GO-ZnO NP nanocomposite as adsorbent. Characterization of this nanocomposite (using Electron Microscopy and Fourier Transform Infrared Spectroscopy) depicted changes in the surface morphology and chemical properties of the adsorbent resulting from MB uptake. Antibacterial properties of the GO-ZnONP nanocomposite was also determined and found to be higher than its individual components. Results indicated that the fabricated adsorbent was highly efficient and may be investigated further for treatment of industrial or domestic effluents.