Enhanced degradation of bisphenol S in water using a combination process of electrochemical oxidation with periodate activation

This paper proposed a new system, electrochemically activated periodate (E/PI) with a Ti/RuO2-IrO2 anode, for the efficient degradation of endocrine disrupting chemical bisphenol S (BPS). The results suggested that the degradation efficiency reached 100 % after 30 min at the conditions of PI 0.25 mM, current density 2 mA/cm2 and pH 7.2. In comparison to other activators of PI (e.g., ultrasonic or visible light) and electrochemically activated different oxidants (e.g., persulfates or H2O2), the E/PI system was found to be more effective in degrading BPS. The system showed a faster degradation rate with increasing current density or PI dose, and demonstrated a strong anti-interference capability against the humic acid and inorganic anions present in water. The system also demonstrated excellent stability, and can still remove 100 % of BPS even after 40 intermittent semi-continuous operations (20 h). The singlet oxygen (1O2) was identified as the primary reactive oxygen species (ROS) for the BPS degradation, as revealed by the free radical quenching and the electron paramagnetic resonance (EPR) experiment. In addition, the intermediates of BPS during its degradation process and main degradation pathways were proposed. The E/PI system can be used as a new AOPs and has practical application potential in water treatment.