Advanced removal of phosphate from water by a novel lanthanum manganese oxide: Performance and mechanism

Abstract

A novel lanthanum manganese oxide (La0.96Mn0.96O3, LMO) was synthesized for advanced phosphate removal to alleviate water eutrophication process. The adsorbent had a specific surface area of 18.51 m2/g with pH at point of zero charge of 6.6; exhibited excellent phosphate adsorption capacity of 168.4mg/g; performed well in a wide pH range from 3 to 10. The phosphate removal was not interfered by coexisting ions. The adsorbent remained 94.8% of its initial adsorption efficiency after reused for four times. Phosphate adsorption process conformed to pseudo-second-order model (R2=0.992) and Langmuir model (R2=0.935). Ligand exchange and electrostatic interaction played important roles in phosphate removal. In addition, the actual sewage secondary effluent was used to further verify the phosphate removal performance of LMO. For practical water treatment, the LMO showed high phosphate removal efficiency of 83.4% and low residual P of 0.1mg/L. LMO is a potential candidate for low-concentration phosphate removal in real water environment.