Mechanistic investigation of mesoporous Mg2+ doped CeO2 encapsulated Fe3O4 core-shells for the selective adsorptive removal of malachite green

Abstract

Economically viable, easy to operate and highly efficient techniques for water treatment are one of the basic amenities that should be provided to every individual in our society. Here we have developed Fe3O4@Mg2+ doped CeO2 core-shells by a co-precipitation route as magnetically retrievable adsorbents which are highly selective towards hazardous malachite green. The developed core-shell nanostructures were well-characterised using XRD, FE SEM, HR TEM, XPS, BET, VSM and TGA. The developed Fe@CMg-1:2 core-shells exhibited a removal efficiency of 95.1% towards Malachite green. Various parameters affecting the adsorption activity were investigated in detail. The nature, extent and mechanism of the adsorption were evaluated using various adsorption isotherm and kinetic models. Dubinin-Radushkevich (D-R), Freundlich and Temkin adsorption models were used to fit the isotherm data and the maximum adsorption capacity (qm) was found to be 18.44 mg g−1 according to Dubinin-Radushkevich (D-R) model. It was found that the selective adsorption of malachite green over Fe@CMg-1:2 core-shells follows heterogeneous multilayer adsorption which obeys pseudo-second-order kinetics. The developed Fe@CMg-1:2 core-shells also exhibited high thermal stability and reusability. Fe@CMg-1:2 core-shells retained 82.4% removal efficiency even after four successive reusability cycles. Easy separation, high selectivity and cost-effectiveness are the highlights of the developed mesoporous Mg2+ doped CeO2 encapsulated Fe3O4 core-shell structures.

Keywords

• Mesoporous core-shells
• Magnetically retrievable adsorbents
• Selective adsorption
• CeO2