Enhanced removal of phosphonates from aqueous solution using PMS/UV/hydrated zirconium oxide process

Traditional treatment processes cannot completely remove phosphonates in circulating cooling water by one-step method. Herein, we designed peroxymonosulfate/UV irradiation/hydrated zirconium oxide (PMS/UV/HZO) coupling process to enhance the phosphonates removal. In particular, nitrilotrismethylenephosphonic acid (NTMP) removal efficiency by PMS/UV/HZO process was much higher than that of PMS/UV process, UV/HZO process and other processes in comparison experiments. Specifically, almost 97.2% NTMP in water was degraded, and the total phosphorous (TP) reduced from 9.3 mg/L to 0.26 mg/L at pH 7 within 180 min. TP removal efficiency still reached above 90% after 5 cycles adsorptiondesorption of HZO. Moreover, Cl over bar , NO 3 over bar and SO 4 2 over bar ions all had negligible effect on NTMP removal. During the process, NTMP was first destroyed to form phosphates and other intermediates by the reactive oxygen species (ROS), then phosphates were in situ immobilized via HZO adsorption. Sulfate radical (SO 4 center dot -) has been confirmed to be the major ROS in the reaction system by quenching experiment and electron paramagnetic resonance (EPR) characterization. And the excellent selective adsorption capacity of HZO for phosphate produced was attributed to the strong inner-sphere coordination between H 2 PO 4 over bar /HPO 4 2 over bar and Zr-OH on the surface of HZO. These results suggest that PMS/UV/HZO process is a promising technique for enhanced phosphonates decontamination. (c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.