Silica-coated magnetite nanoparticles as a novel adsorbent for the removal of Iron(II) and Manganese(II) from surface water: Equilibrium, kinetics and thermodynamic studies

Silica-coated magnetite nanoparticle was synthesized as model adsorbent for the removal of Fe(II) and Mn(II) which are major contaminants of surface water. Prepared adsorbent was fully characterized using Fourier Transform Infra-red spectroscopy, Scanning Electron Microscopy, X-Ray Diffraction and X-Ray Fluorescence. The optimum conditions of adsorption were determined by investigating the effect of initial metal ion concentration, contact time, adsorbent dose, pH of aqueous solution and temperature. Adsorption equilibrium time was found to be 60 min for both Fe(II) and Mn(II). The equilibrium adsorption experimental data for the two metals were found to fit the Langmuir adsorption isotherms best with a regression value of 0.989 and 0.979 for Fe(II) and Mn(II) respectively. The pseudo second order kinetic model was found to describe the adsorption kinetics for both metals more effectively. The adsorption processes involving both metals were endothermic. The adsorbent was finally applied to typical raw water with initial manganese and iron concentrations of 1.45 mg/l and 3.67 mg/l, respectively, and the removal efficiency was 90 % for Mn and 47 % for Fe