Synergistic effect between UV and chlorine (UV/chlorine) on the degradation of carbamazepine: Influence factors and radical species.
For successful wastewater reclamation, advanced oxidation processes have attracted attention for elimination of emerging contaminants. In this study, the synergistic treatment with UV irradiation and chlorine (UV/chlorine) was used to degrade carbamazepine (CBZ). Neither UV irradiation alone nor chlorination alone could efficiently degraded CBZ. UV/chlorine oxidation showed a significant synergistic effect on CBZ degradation through generation of radical species (OH and Cl), and this process could be well depicted by pseudo first order kinetic. The degradation rate constants (kobs,CBZ) of CBZ increased linearly with increasing UV irradiance and chlorine dosage. The degradation of CBZ by UV/chlorine in acidic solutions was more efficient than that in basic solutions mainly due to the effect of pH on the dissociation of HOCl and OCl(-) and then on the quantum yields and radical species quenching of UV/chlorine. When pH was increased from 5.5 to 9.5, the rate constants of degradation of CBZ by OH decreased from 0.65 to 0.14 min(-1) and that by Cl decreased from 0.40 to 0.11 min(-1). The rate constant for the reaction between Cl and CBZ was 5.6 ± 1.6 × 10(10) M(-1) s(-1). Anions of HCO3(-) (1-50 mM) showed moderate inhibition of CBZ degradation by UV/chlorine, while Cl(-) did not. UV/chlorine could efficiently degrade CBZ in wastewater treatment plant effluent, although the degradation was inhibited by about 30% compared with that in ultrapure water with chlorine dosage of 0.14-0.56 mM. Nine main oxidation products of the CBZ degradation by UV/chlorine were identified using the HPLC-QToF MS/MS. Initial oxidation products arose from hydroxylation, carboxylation and hydrogen atom abstraction of CBZ by OH and Cl, and were then further oxidized to generate acylamino cleavage and decarboxylation products of acridine and acridione.
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China; Shenzhen Laboratory of Microorganism Application and Risk Control, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, PR China.
Wen-Long
WL
Wang
Shenzhen Laboratory of Microorganism Application and Risk Control, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, PR China. Electronic address: wuqianyuan@tsinghua.edu.cn.
Qian-Yuan
QY
Wu
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China.
Nan
N
Huang
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China; Shenzhen Laboratory of Microorganism Application and Risk Control, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, PR China.
Ting
T
Wang
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China; Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, Shenzhen 518055, PR China. Electronic address: hyhu@tsinghua.edu.cn.
Hong-Ying
HY
Hu
D002220:Carbamazepine; D002713:Chlorine; D010084:Oxidation-Reduction; D053719:Tandem Mass Spectrometry; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical; D018508:Water Purification
D014874:Water Pollutants, Chemical; D002220:Carbamazepine; D002713:Chlorine
Carbamazepine; Chlorine radical; Hydroxyl radical; UV/Chlorine oxidation; Wastewater reclamation