Facile synthesis of muscovite–supported Fe3O4 nanoparticles as an adsorbent and heterogeneous catalyst for effective removal of methyl orange: Characterisation, modelling, and mechanism

Abstract

The discharge of organic pollutants including dyes into the aquatic system represents a main source of environmental contamination. Decontamination of dye molecules from polluted water bodies through adsorption process is reported to be an effective and economic technology. Herein, a one-pot preparation method was used to decorate the available and low-cost layered silicate muscovite (MUS) mica by iron oxide (Fe3O4) nanoparticles. The new Fe3O4@MUS composite was characterised by XRD, FTIR, SEM, and TEM techniques and tested for the adsorption and Fenton-like degradation of hazardous methyl orange (MO). The results of experimental parameters such as reaction time, Fe3O4@MUS mass, MO concentration, solution pH, H2O2 concentration, and temperature indicated that Fenton-like oxidation process was rapid (i.e., around 98 % of MO removal was achieved after 60 min). The pseudo-first-order for kinetics and Langmuir for equilibrium models fitted the MO adsorption data. The maximum Langmuir uptake capacity of Fe3O4@MUS presented the value of 149.25 mg/g at 25°C. Fenton-like degradation data followed the first-order removal rate at varied initial concentrations (i.e., 50, 100, and 150 mg/L) of MO dye. Electrostatic interactions, hydrogen bonding, and the π-π bond (i.e., dye‒dye interaction) were involved during MO adsorption onto Fe3O4@MUS surface. Degradation of MO was mainly associated with the generation of •OH radicals through H2O2 catalytic decomposition using Fe3O4@MUS composite. The synthetic catalyst was reused up to five runs without an apparent decrease in its removal efficiency even after 5th use, reflecting the high stability of Fe3O4@MUS.