Equilibrium and kinetics studies of adsorption phosphate on raw and novel lithium silica fume based adsorbent

AbstractIn this study, the adsorption of phosphate from aqueous solution by lithium silica fume (LSF) with or without iron oxides modification was investigated. Iron oxides modification was achieved by in situ generation of iron oxides on LSF by applying three different kinds of ferric solution (FeCl3·6H2O, Fe(NO3)3·9H2O, and Fe2(SO4)3) with Na2CO3 addition. Batch adsorption studies were carried out for better understanding of their adsorption behaviors towards phosphate. Among three iron oxide modified adsorbents, FeCl3-modified LSF (FeCl3/LSF) exhibited highest SBET, and best adsorptive capability towards phosphate. The adsorption kinetics data of phosphate adsorption onto FeCl3/LSF fitted well with Langmuir model and Freundlich model. The maximum phosphate adsorption capacity onto FeCl3/LSF is 13.39 mg g−1 at 25°C, almost three times higher than that of LSF. The X-ray diffraction pattern showed new species of Fe(PO3)3 that was formed on FeCl3/LSF after adsorbing onto phosphate, which indicated chemisor...