Measurement and modeling of atrazine degradation kinetics in flow-through UV/H2O2 reactors
ZHAN Lumeng1,2,3,, LI Wentao1, LI Mengkai1, JENSEN Marina Bergen2,3, ZHANG Miao4, QIANG Zhimin1,3,, 1.Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, China Academy Scienles, Beijing 100085, China 2.Department of Geosciences and Natural Resource Management China Academy Sciences, University of Copenhagen, Frederiksberg C 1985, Denmark 3.Sino-Danish College of University of Chinese Academy Sciences, Beijing 100049, China 4.School of Civil and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
Abstract:UV-based advanced oxidation processes are promising in micropollutant removal from water with abundant relative researches accomplished in batch reactors, while the different flow pattern in practical flow-through UV reactors may lead to a varied reaction kinetic and process efficiency. In this study, the kinetics of atrazine (ATZ) degradation in flow-through UV/H2O2 reactors were investigated, and the impacts of H2O2 concentration and internal reactor diameter on ATZ removal efficiency and the process energy efficiency were evaluated. The steady-state assumption (SSA) model was developed to predict the degradation kinetics of atrazine under various experimental conditions, and its accuracy was tested by comparing with experimental data. The results showed that the efficient degradation of ATZ occurred in flow-through UV/H2O2 reactors and it followed the pseudo first-order kinetics (R2>0.95). Despite the fact that the flow was not fully mixed, SSA model exhibited good accuracy in predicting the degradation of target pollutant in flow-through reactors with deviations generally less than 20%. Within the investigated concentration range, ATZ degradation rate in different reactors increased with the rising of H2O2 concentration, and reached 5.8×10?2 s?1 in the reactor with an internal diameter of 35 mm when H2O2 concentration was 0.2 mmol·L?1, which was 4 times as much as that in UV radiation alone. The increasing reactor diameter resulted in a low time-based ATZ degradation rate constant on account of the changes in average fluence rate, while had slight effect on the fluence-based ATZ degradation rate constant. Finally, based on the electrical energy per order (EEO) calculation, the energy efficiency in removing ATZ can be reduced by increasing H2O2 concentration and reactor diameter. Key words:UV/H2O2/ flow-through reactor/ steady-state assumption model/ degradation rate/ electrical energy per order.
图1过流式UV/H2O2反应装置示意图 Figure1.Schematic diagram of a flow-through UV/H2O2 reactor
下载: 导出CSV 表2不同反应条件下实验和模拟得到的ATZ拟一级降解速率常数 Table2.Observed and calculated pseudo-first order rate constants of atrazine degradation under various conditions
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1.Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, China Academy Scienles, Beijing 100085, China 2.Department of Geosciences and Natural Resource Management China Academy Sciences, University of Copenhagen, Frederiksberg C 1985, Denmark 3.Sino-Danish College of University of Chinese Academy Sciences, Beijing 100049, China 4.School of Civil and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China Received Date: 2020-08-05 Accepted Date: 2020-11-06 Available Online: 2021-03-24 Keywords:UV/H2O2/ flow-through reactor/ steady-state assumption model/ degradation rate/ electrical energy per order Abstract:UV-based advanced oxidation processes are promising in micropollutant removal from water with abundant relative researches accomplished in batch reactors, while the different flow pattern in practical flow-through UV reactors may lead to a varied reaction kinetic and process efficiency. In this study, the kinetics of atrazine (ATZ) degradation in flow-through UV/H2O2 reactors were investigated, and the impacts of H2O2 concentration and internal reactor diameter on ATZ removal efficiency and the process energy efficiency were evaluated. The steady-state assumption (SSA) model was developed to predict the degradation kinetics of atrazine under various experimental conditions, and its accuracy was tested by comparing with experimental data. The results showed that the efficient degradation of ATZ occurred in flow-through UV/H2O2 reactors and it followed the pseudo first-order kinetics (R2>0.95). Despite the fact that the flow was not fully mixed, SSA model exhibited good accuracy in predicting the degradation of target pollutant in flow-through reactors with deviations generally less than 20%. Within the investigated concentration range, ATZ degradation rate in different reactors increased with the rising of H2O2 concentration, and reached 5.8×10?2 s?1 in the reactor with an internal diameter of 35 mm when H2O2 concentration was 0.2 mmol·L?1, which was 4 times as much as that in UV radiation alone. The increasing reactor diameter resulted in a low time-based ATZ degradation rate constant on account of the changes in average fluence rate, while had slight effect on the fluence-based ATZ degradation rate constant. Finally, based on the electrical energy per order (EEO) calculation, the energy efficiency in removing ATZ can be reduced by increasing H2O2 concentration and reactor diameter.
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