Highly stable removal of low concentration phosphorus by mechanically activated FeCO3: In situ synergistic mechanisms

Abstract

Excess phosphorus (P) in surface water poses a serious threat to ecological safety. However, current methods for effectively removing low concentrations of phosphorus are complicated and expensive. Herein, we used one-step mechanical activation to enhance the release of alkalinity from carbonates and to stimulate ferrous activity in situ, thus achieving efficient and stable removal of phosphorus at low concentrations. The resultant activated FeCO3 was demonstrated to be a high-performance material, which can remove more than 92% of the actual low concentration of phosphorus pollution within 30 min, and the concentration of the effluent steadily met the requirements of Chinese Class I environmental quality standards for surface water (0.02 mg/L). In addition, mechanistic investigation showed that mechanical activation significantly enhanced the reactivity and phosphorus removal performance of MgCO3. Moreover, one-step mechanical activation simultaneously stimulates the release of alkaline and ferrous ionic groups from iron-rich FeCO3, which can produce highly active trivalent iron oxides in situ, leading to efficient and stable phosphorus removal at low concentrations. The present work provides a new insight and direction for developing high-performance materials to remediate low concentration phosphorus polluted waters.