Novel effective waste iron oxide- coated magnetic adsorbent for phosphate adsorption

The study investigates the adsorptive interactions of phosphate with fresh and modified waste iron oxide-coated magnetic materials (FOMs) in aqueous medium. The Brunauer Emmett Teller surface area of modified FOM is 274.8m(2)/g, providing extensive open adsorption sites for phosphate removal. Scanning electron microscope observations revealed that FOM has a fractured and rough surface morphology. The optimal adsorption capacity of modified FOM is 30.8mgP/g which is better than fresh one in the pH 5. The adsorption process follows a pseudo-second-order kinetics with rate constant amounted to 4.1x10(4) and 3x10(2)g/mgh with phosphate concentration from 11.1 to 140.9mg/l. The adsorption isotherms are fitted into the Langmuir model in which the co-relationship is 0.999 in this study. The low activation energy is obtained as 2.7kJ/mol, which is the physisorption. The negative standard enthalpy and negative adsorption standard free energy in this study indicates that the adsorption of phosphate by the modified FOM adsorbent is exothermic and spontaneous reaction. The calculated maximum adsorption capacity is 30.8mgP/g which was much higher than previous reported.