Iodine-enhanced ultrasound degradation of sulfamethazine in water

•An iodine-enhanced ultrasound system was proposed to degrade SMT in water.•UV-Vis spectra showed that SMT degradation was correlated with the molecular I2.•Compared with HO, I and I2−·radicals played more important role on SMT degradation.•Factors affecting radicals’ formation and subsequent SMT de...

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Veröffentlicht in:Ultrasonics sonochemistry 2018-04, Vol.42, p.759-767
Hauptverfasser: Yang, Xiao-yu, Wei, Hong, Li, Ke-bin, He, Qiang, Xie, Jian-cang, Zhang, Jia-tong
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Sprache:eng
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Zusammenfassung:•An iodine-enhanced ultrasound system was proposed to degrade SMT in water.•UV-Vis spectra showed that SMT degradation was correlated with the molecular I2.•Compared with HO, I and I2−·radicals played more important role on SMT degradation.•Factors affecting radicals’ formation and subsequent SMT degradation were studied. This study investigated sulfamethazine (SMT) ultrasound degradation, enhanced by iodine radicals, generated by potassium iodide (KI) and hydrogen peroxide (H2O2) in situ. The results showed that the ultrasound/H2O2/KI (US/H2O2/KI) combination treatment achieved an 85.10 ± 0.45% SMT removal (%) in 60 min under the following conditions: pH = 3.2, ultrasound power of 195 W, initial SMT concentration of 0.04 mmol·L−1, H2O2 concentration of 120 mmol·L−1, and KI concentration of 2.4 mmol·L−1. UV-Vis spectrophotometric monitoring of molecular iodine (I2) and triiodide (I3−) revealed a correlation between the SMT degradation and the iodine change in the solution. Quenching experiments using methanol, t-butanol and thiamazole as radical scavengers indicated that iodine radicals, such as I and I2−, were more important than hydroxyl radicals (HO) for SMT degradation. SMT degradation under the US/H2O2/KI treatment followed pseudo-first order reaction kinetics. The activation energy (Ea) of SMT degradation was 7.75 ± 0.61 kJ·mol−1, which suggested the reaction was controlled by the diffusion step. Moreover, TOC removal was monitored, and the obtained results revealed that it was not as effective as SMT degradation under the US/H2O2/KI system.
ISSN:1350-4177
1873-2828
DOI:10.1016/j.ultsonch.2017.12.045