Effects of amine (APTES) and thiol (MPTMS) silanes-functionalized ZnO NPs on the structural, morphological and, selective sonophotocatalysis of mixed pollutants: Box–Behnken design (BBD)

Abstract

The lack of selectivity of Zinc oxide nanoparticles (ZnO NPs) in the wastewater purification process is considered a severe limitation. This research aims to use surface-modified ZnO NPs with different surface charges for selective removal of methyl orange (MO) and methylene blue (MB) dyes from an aqueous mixture solution. The sonophotocatalyst process was investigated to improve the selective oxidation of the aqueous mixture. The surface of the ZnO NPs has been modified with a silane coupling agent (APTES and MPTMS) to get active surface functional groups. The synthesized modified ZnO NPs were characterized by XRD, FE-SEM, TEM and FTIR analysis. The surface charge and absorption spectrum were investigated using Zeta potential and UV-Vis spectrophotometer approaches, respectively. The selective sonophotocatalytic of anionic MO and cationic MB dyes was performed via APTES-ZnO and MPTMS-ZnO NPs, respectively. The selective removal was optimized using Response Surface Methodology (RSM) based on the Box–Behnken Design (BBD). To this end, the effects of catalyst dosage, dye concentration, and reaction time on selective removal were investigated under various experimental conditions. The results revealed that unmodified ZnO NPs have no selectivity in the decomposition of an MO and MB mixed, whiles the change in surface charges of ZnO NPs has been shown to change significantly the selectivity efficiency of ZnO NPs.