Fe₂O₃-Mg-Al supported beads for phosphate removal

Abstract

The phosphate removal in surface water by adsorption on Mg-Al LDHs and Fe₂O₃-Mg-Al LDHs or layered double hydroxides was investigated. The materials were synthesized by co-precipitation method in and 2:1 and 0.05:2:1 weight ratio as Mg-Al and Fe₂O₃-Mg-Al, respectively. Their structure formed in layered double hydroxides (LDHs) was confirmed by XRD, SEM, XRF, FT-IR and BET specific surface area. The introduction of Fe₂O₃ into the main structure increased the specific surface area and affected the phosphate adsorption capacity. Based on Langmuir isotherm, 31 mg P/g Fe₂O₃-Mg-Al LDHs was observed. Adsorption kinetic followed pseudo-second-order kinetic model with respect to phosphate concentration. The synthesized materials were applied to the fabrication of granular adsorbent for use in the wastewater treatment. The phosphate adsorption capacity obtained by material via mechanical coating was higher than that using extrusion technique. In conclusion, both types (powder and pellet) of Fe₂O₃-Mg-Al LDHs could be an alternative material for the removal of phosphate for the surface water.