Green synthesis of nickel oxide nanoparticles using Allium cepa peels for degradation of Congo Red Direct Dye: an environmental remedial approach
Abstract Direct dyes are used in different textile operations and processings. The textile industries are disposing of unused direct dyes into the aquatic environment which is posing a serious alarming threat to aquatic lives. The current study deals with the synthesis of nickel oxide nanoparticles using Allium cepa peels aqueous extract. Nickel oxide nanoparticles (NiO-NPs) were characterized by SEM. Synthesized NiO-NPs were used to remove Congo red direct dye. Various experimental factors like concentration of dye & nanoparticles, pH, and temperature were optimized. Congo red direct dye was decolorized up to 90% at optimized conditions (Congo Red Direct dye concentration 0.02%, catalyst dose 0.003 g·L−1, pH 6, and temperature (50 °C). The real textile industry effluent disclosed 70% decolorization at optimized conditions. The percent reduction in TOC and COD were found to be 73.24% and 74.56%, in the case of congo red dye catalytic treatment & the percent reduction in TOC and COD were found to be 62.47% and 60.23%, respectively in the treatment of textile effluent using nickel oxide nanoparticles as a catalyst. Treated and untreated dye samples were exposed to FTIR and UV-Visible spectral analyses too. The reaction products were studied by degradation pathway.