Magnetite-based nanoparticles as an efficient hybrid heterogeneous adsorption/oxidation process for reactive textile dye removal from wastewater matrix

Abstract

ABSTRACT The wide application of reactive dyes in textile manufacturing has posed a threat to the ecological system and human beings, therefore their use attracted increase attention. Magnetite is one of ubiquitous earth minerals, which has a high adsorption capacity for contaminants and its oxidation ability, could be initiated by H2O2 for the formation of hydroxyl free radicals (•OH) for oxidising the reactive Levafix Blue dye. The objective of this study is to develop enhanced combined adsorption/oxidation technology. Magnetite is synthesised under mild experimental conditions and its homogeneous chemical composition and morphology is revealed using X-Ray Diffraction (XRD) and high-resolution Transmission Electron Microscope (TEM) and then applied for reactive dye removal. Box-Behnken design based on Response Surface Methodology (RSM) is applied for optimising the operational parameters effect, namely, Fe2+/3+, H2O2 doses and pH on the dye removal efficiency. The model with a high correlation coefficient (R2 = 94%) predictions is in appropriate agreement with the experimental results. The optimised model results revealed the system optimal pH is obtained at 2.5 using 48 and 828 mg/L of magnetite and H2O2, respectively, to attain a complete dye removal, 100%, within 30 minutes or irradiance time. Finally, the experimental results illustrated that the reaction is exothermic, non-spontaneous in nature and follows the second-order reaction kinetics rate model with a low activation energy corresponding to −26.39 kJ/mol. The laboratory results from such investigation can be evaluated in future research to be applied for practical and real scales.