Ammonia Removal from Aqueous Solution by Zeolites Synthesized from Coal Fly Ash

The removal of ammonia from aqueous solutions using zeolites (ZFAs) synthesized from coal fly ash (CFA) as low-cost absorbent was investigated in a batch mode. When raw CFA was subjected to alkaline hydrothermal zeolite synthesis, the Zeolite X (ZFA-X) and zeolite A (ZFA-A) were formed. ZFAs had a much greater ability than CFA to remove ammonia. The pH strongly influenced ammonia removal by ZFAs. The higher removal efficiency was achieved when operating at pH between 6.5 and 8.5 for the ZFAs. From ammonia solution of initial concentration equal to 100 mg/L, the removal percentage reached values of 18.4, 76.8, and 82.1%, respectively, for CFA, ZFA-A and ZFA-X at room temperature, pH = 7.5, sorbent dose of 15 g/L, and contact time of 0.5 h. The experimental results indicated that ZFAs may be promising materials for the purification of ammonia from water/wastewater.