Removal of Ammonia Nitrogen From Water by Magnetic Zeolite and High-Gradient Magnetic Separation

We have studied the removal of ammonia nitrogen from water by a magnetic zeolite (MZL) and a high-gradient magnetic separation (HGMS) to explore the possibility of an advanced water purification process. MZL was synthesized by the coprecipitation process using fly ash, sodium hydroxide solution, and ferric chloride solution. Large magnetization of over 10 A · m2/kg at 2 T was derived for the typical MZL. The adsorption ratio of ammonia nitrogen for MZL achieved 83.4% in a 0.8-mg/L ammonia nitrogen solution. The adsorbed ammonia nitrogen could be released easily by NaCl solution due to an ion exchange reaction between Na and ammonia ions. Magnetic separation properties of MZL were studied by HGMS system with a superconducting magnet. At flow velocity of 0.5 m/s and 2 T, 99.8% of MZL could be magnetically separated.