The comparative study of a nano-Fe0-loaded and a nano-Fe/Ce-loaded expanded-perlite on removal of phosphate from water

Abstract

Adsorbents, nano-Fe0-loaded expanded-perlite (nFe@EP) and nano-Fe/Ce loaded expanded-perlite (nFe-Ce@EP) were prepared by the chemical reduction method and their performances on phosphate uptake were compared under different conditions. Results showed that both of nFe@EP and nFe-Ce@EP exhibited good adsorption properties, whereas nFe-Ce@EP had better performances than nFe@EP in almost all investigated cases, with the higher P removal efficiency, shorter equilibrium time, less dosage and more favorable final pH. The physicochemical characteristics of both adsorbents before and after reaction were characterized and implied that the main mechanism for phosphate removal was electrostatic attraction and ligand complexation, besides co-precipitation for nFe@EP. Both adsorption processes could be described accurately by pseudo-second-order model, while Langmuir for nFe@EP and Freundlich for nFe-Ce@EP were the more suitable model, respectively. In the application to municipal wastewater, nFe-Ce@EP exhibited the much better performances on phosphate removal with residual phosphate of 0.003 mg L−1. Especially after five consecutive adsorption-desorption cycles, phosphate removal rate was still above 87 %. Moreover, removals of a complete phosphate and 62.8 % nitrate from Fenhe Park surface water were achieved by nFe-Ce@EP simultaneously. Thereby, nFe-Ce@EP is a more efficient adsorbent for alleviating the eutrophication of water, with its excellent uptake performance, high selectivity and reusability.