Chloride-Enhanced Fe(II)/PMS/H2O2 System for Degradation of PBTC and Simultaneous Recovery of Iron Phosphate

• • Achieved 100% total phosphorus (TP) removal from 0.1 mmol/L PBTC within 60 min using Fe(II)/PMS/H2O2/NaCl system at pH 3.0, with Fe(II) 1.0 mmol/L, PMS and H2O2 each 0.5 mmol/L, and NaCl 10 mmol/L, enabling near-complete phosphorus recovery as FePO4 precipitate. • • Chloride (Cl−) at 10 mmol/L enhanced the generation of reactive species (•OH, SO4•−, Cl•, Cl2•−), with •OH identified as the dominant oxidant; Cl• and Cl2•− specifically targeted C–P bonds, improving phosphorus release and subsequent FePO4 formation. • • Solution pH critically governed FePO4 precipitation: acidic conditions (pH < 4.3) favored FePO4 formation, while higher pH shifted speciation, underscoring the need for pH control in practical applications. • • Coexisting HCO3− and humic acid (HA) significantly inhibited TP removal in a concentration-dependent manner, whereas Ca2+ and Mg2+ had negligible interference, indicating system robustness in hard waters but vulnerability to organic matter and alkalinity.