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| Degradation of 1,1,1-Trichloroethane and 1,4-Dioxane Co-existed in Groundwater by Ultrasonics-Oxidant Systems |
| Received:May 25, 2015 |
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| KeyWord:1,1,1-trichloroethane;1,4-dioxane;groundwater contamination;ultrasonics;joint degradation |
| Author Name | Affiliation | E-mail | | LI Bing-zhi | Shanghai Academy of Environmental Sciences, Shanghai 200233, China | | | ZHU Jiang | Shanghai Academy of Environmental Sciences, Shanghai 200233, China | jzh@sjtu.edu.cn |
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| Abstract: |
| In China there is little information available about the degradation of 1,1,1-trichloroethane(TCA) and 1,4-dioxane(1,4-D) in groundwater. Here the efficiencies, influencing factors and acute toxicity effects of TCS and 1,4-D degradation in ultrasonics(US) and/or oxidants[persulfate(PS) and H2O2] systems were examined. Results showed that the "US+PS+H2O2" system exhibited the best treatment performance, in which 100% of TCA and 33% of 1,4-D were degraded within 4 h at 25 ℃, initial pH of 8.2, oxidant/1,4-D molar ratio of 200:1, ultrasonic frequency of 400 kHz, ultrasonic intensity of 2.67 W·cm-2 and power of 100 W. Oxidants(PS and H2O2) and reaction temperature had important impacts on the removal of TCA and 1,4-D. The optimum oxidant doses were:H2O2/1,4-D=200:1, and PS/1,4-D=1000:1. At a constant temperature of 25 ℃, TCA and 1,4-D were completely removed after 6 h and 10 h, and the acute toxicities of treated groundwater were decreased by 98.81% and 99.87%, respectively. Rising temperature gradually to 60 ℃ enhanced the degradation rates of target pollutants, and shortened degradation time by 1 h and 3 h, respectively. These results show that ultrasonics plus oxidants is a promising method for remediating concurrently contaminated groundwater with TCA and 1,4-D. |
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