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

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, Fe^2+/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.

KEYWORDS:

• Catalytic oxidation
• adsorption
• dye
• kinetics
• response surface methodology
• optimisation
• experimental design

Disclosure statement

The authors declare that there is no conflict of interest.