Phosphate removal from water by a novel zeolite/lanthanum hydroxide hybrid material prepared from coal fly ash

Abstract

This study was undertaken to investigate the effectiveness of the hybrid adsorbent, which was synthesized from coal fly ash and was composed of lanthanum hydroxide and zeolite (La-ZFA), for phosphate removal from water. Long-term repeated adsorption tests for 30 days showed that the maximum removal capacity of the material reached 66.09 mg P/g. The fractionation of adsorbed phosphorus indicated that phosphate immobilized by La-ZFA was quite irreversible and was dominated by HCl-P fraction. It was suggested that the immobilization of phosphate was mainly attributed to lanthanum hydroxide and was slightly influenced by coexistence of other anions (Cl⁻, NO₃⁻, SO₄²⁻, and HCO₃⁻). At a La/P molar ratio between 1.5:1 and 2.0:1, a nearly complete removal (above 98%) of phosphate could be achieved. La-ZFA also exhibited great performance for removing phosphate from lake water (97.29%) as well as the effluent from wastewater treatment plant (97.86%), respectively. In addition, based on the results of the present study, it was believed that La-ZFA could be a potential material for phosphate removal in practical application.

Keywords:

• Adsorption
• lanthanum
• phosphate
• wastewater
• zeolite

Acknowledgments

We thank Dr. S. Tabassum for assistance in improving the presented manuscript.

Funding

This research was supported by the National Key Project for Water Pollution Control (2012ZX07105002-03).