Facile development of sunlit ZnO nanoparticles-activated carbon hybrid from pernicious weed as an operative nano-adsorbent for removal of methylene blue and chromium from aqueous solution: Extended application in tannery industrial wastewater

In this study, zinc oxide nanoparticles (ZnO-NPs) and activated carbon (AC) are produced from parthenium weed plant using a green synthesis technique. ZnO-NPs loaded parthenium weed activated carbon (ZnONPs-PWAC) is used to remove pollutants (Methylene Blue (MB) and Chromium (Cr (VI)) from aqueous solution and also extended to treat with real industrial tannery wastewater. A comprehensive analysis is done with various forms of ZnO based particles (ZnO-NPs, ZnONPs-PWAC) to test its photocatalytic activity. Further, the photocatalytic activity of biosynthesized ZnO-NPs is evaluated by measuring the efficiency of decolorization (>93%) for different dyes (Malachite Green, Congo Red, and Methylene Blue) under sunlight irradiation. The maximum removal (> 99%) of MB is obtained at 60 min by ZnONPs-PWAC and 130 min by PWAC. The maximum equilibrium percentage removal of Cr (VI) is found to be 99% around 90 min for ZnONPs-PWAC and 160 min for PWAC. The enhancement in removal efficiency is due to the combined reaction of photocatalysis and adsorption. The parameters such as pollutant concentration, pH, and the amount of ZnONPs-PWAC are varied to understand its effective removal of MB and Cr (VI) in wastewater. Moreover, the efficiency of ZnONPs-PWAC is found to be more than 92% against industrial tannery wastewater. Overall, ZnONPs-PWAC can be used as an alternative and operative material to remove MB and Cr (VI) in wastewater treatment. (C) 2019 Elsevier B.V. All rights reserved.