title: Elucidating ozonation mechanisms of organic micropollutants based on DFT calculations: Taking sulfamethoxazole as a case.
abstract: Ozonation is widely used in wastewater treatment plants to remove diverse organic micropollutants. As molecular structures of organic micropollutants contain multiple ozone-preferred reaction sites, and moreover intermediate products can react with ozone again, ozonation mechanism is complex. A fast increasing number of organic micropollutants and a great demand of ecological risk assessments call for an in silico method to provide insights into the ozonation mechanism of organic micropollutants. Here, an in silico model was developed to unveil ozonation mechanisms of organic micropollutants. Sulfamethoxazole was taken as a case. The model enumerates elementary reactions following well-accepted ozonation patterns and secondary transformation reactions established for intermediates by experiments. Density functional theory (DFT) calculations were employed for evaluating thermodynamic feasibilities of reaction pathways. By calculating Gibbs free energies, ozonation products of SMX were predicted. The predicted products are consistent with those detected in experiments. This method is advanced in revealing all possible reaction pathways including minor pathways that produce toxic byproducts but are difficult to be observed by experiments. Accordingly, water treatment engineers can setup necessary treatment technology to ensure water safety.
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, and Institute of Applied Ecology, Chinese Academy of Science, Shenyang 110016, China.
authors.forename: Siyu
authors.initials: S
authors.lastname: Zhang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, POPs Research Center, Tsinghua University, Beijing, 100084, China; Veolia Environment Joint Research Center for Advanced Technology, Tsinghua University, Beijing, 100084, China. Electronic address: yg-den@tsinghua.edu.cn.
authors.forename: Gang
authors.initials: G
authors.lastname: Yu
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Chen
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, and Institute of Applied Ecology, Chinese Academy of Science, Shenyang 110016, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, and Institute of Applied Ecology, Chinese Academy of Science, Shenyang 110016, China.
authors.forename: Xuejiao
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, POPs Research Center, Tsinghua University, Beijing, 100084, China; Veolia Environment Joint Research Center for Advanced Technology, Tsinghua University, Beijing, 100084, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, POPs Research Center, Tsinghua University, Beijing, 100084, China; Veolia Environment Joint Research Center for Advanced Technology, Tsinghua University, Beijing, 100084, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Huang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, POPs Research Center, Tsinghua University, Beijing, 100084, China; Veolia Environment Joint Research Center for Advanced Technology, Tsinghua University, Beijing, 100084, China.
authors.forename: Shubo
authors.initials: S
authors.lastname: Deng
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, POPs Research Center, Tsinghua University, Beijing, 100084, China; Veolia Environment Joint Research Center for Advanced Technology, Tsinghua University, Beijing, 100084, China.
authors.forename: Yujue
authors.initials: Y
authors.lastname: Wang
mesh_terms: D010126:Ozone / Q000737:chemistry*; D013420:Sulfamethoxazole / Q000032:analysis* / Q000737:chemistry; D013816:Thermodynamics; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D010126:Ozone; D013420:Sulfamethoxazole; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Density functional theory; Gibbs free energy; Organic micropollutant; Ozonation mechanism; Sulfamethoxazole