Degradation of emerging contaminants in water by a novel non-thermal plasma/periodate advanced oxidation process: Performance and mechanisms

This work proposed a novel activation strategy of periodate (PI) by non-thermal plasma (NTP) for degradation of emerging contaminants in water. Results demonstrated that PI could be successfully activated by NTP and promoted the degradation of sulfadiazine (SDZ). When amount of PI was 6 mmol/L, the performance of activation achieved the highest. SDZ degradation efficiency reached 98.9 % within 12 min under NTP/PI system, which was 25.2 % higher than that in sole NTP system. The hv, H center dot, H2O2 and electrons generated by NTP may be involved in PI activation. Active species including center dot OH, IO3 center dot, 1O2, O2 center dot- and electrons were proven to play role in SDZ degradation. The active species dominated to SDZ degradation were explored based on experiments and density functional theory (DFT). The toxicity of SDZ was declined after NTP/PI treatment. Higher input power and lower concentration were conductive to degradation of SDZ. Compared with alkaline and neutral condition, higher degradation efficiency of SDZ was attained at acidic condition. TOC and COD removal both increased with addition of PI. NTP/PI system was proven to be suitable for efficient removal of other emerging contaminants including sulfamethoxazole, bisphenol A and ciprofloxacin. In different water bodies, SDZ can also be effectively removed by NTP/PI system. The energy efficiency (G50) of NTP/PI for SDZ degradation could reach 230.77 mg/ kWh, which was much higher that of the reported methods.