The impact of the magnetite nanoparticles on the physicochemical and adsorption properties of the magnetic alginate beads

Abstract In this study, calcium alginate-based adsorbents with magnetic and non-magnetic properties (MABs and ABs) were prepared and the impact of the incorporated magnetite nanoparticles (Fe3O4 NPs) on the physicochemical properties, adsorption kinetics and Cu(II) uptake mechanism was determined. ABs and MABs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and superconducting quantum interference device magnetometer (SQUID). The SEM analysis of the MABs showed that the composite has a rough surface with abundant protuberances. The XRD analysis showed an amorphous structure of the ABs. The TGA analysis revealed higher thermal stability of the MABs compared to ABs. The MABs proved to be superparamagnetic at room temperature. The adsorption experiments of copper ions onto ABs and MABs were also carried out. It was revealed that for the same weight of the alginate matrix, the MABs and the ABs have an adsorption efficiency of 54.9 and 66.7 mg/g, respectively. The adsorption kinetics were followed by a pseudo-second-order kinetic model and the diffusion properties played a significant role in the control of the adsorption kinetics. The adsorption equilibrium rate constant (k2) for the pseudo-second-order model was found to be 1.98 × 10-4 g. mg-1. min-1 for ABs and 3.8 × 10-4 g. mg-1. min-1 for MABs.