▎ 摘 要
This study presents a simple method for facile synthesis of core-shell microspheres of Graphene oxide-MnO2Goethite (GO-MnO2-Goe). Synthesised GO was used as the core material for treatment with the pre-decided molar ratio mixture of Fe and Mn to form a MnO2-Goe shell over the GO surface optimising various parameters. Subsequently the GO-MnO2-Goe nanoparticles were impregnated into alginate polymer to form GO-MnO2Goethite impregnated alginate hydrogel beads (GO-MnO2-Goe-Ca-Alg) using displacement reaction. The product was characterized by XRD, FTIR, BET, SEM-EDS and zeta potential measurement. The GO-MnO2-Goe-Ca-Alg hybrid nanosorbent was used to efficiently remove both arsenic (III) and arsenic (V) from groundwater (80-96 % for 0.1-100 mu g mL-1 concentration range) at pH 4-6. Uptake processes for both As (III) and As (V) followed Langmuir isotherm model with maximum sorption capacity evaluated as 27.53 and 34.17 mg g-1 respectively for As (III) and As (V). The reaction kinetics, thermodynamic parameters, interparticle diffusion model were studied. Mechanism of uptake was suggested based on fraction diagram of As (III) and As (V) species along with zeta potential of GO-MnO2-Goe at various pH. The in-situ transformation of As (III) to As (V) before its sorption was investigated and explained with the help of XPS analysis.