https://scholars.lib.ntu.edu.tw/handle/123456789/76486
標題: | Mathematical model for formation decontamination by pumping with well bore mixing | 作者: | Chen, Jui-Sheng Liang, Ching-Ping Gau, Hwa-Sheng Liu, Chen-Wuing |
關鍵字: | Well bore mixing;Formation;Decontamination;Pumping | 公開日期: | 25-五月-2005 | 出版社: | Taipei:National Taiwan University Dept Comp Sci Informat Engn | 卷: | vol.30 | 起(迄)頁: | 446-457 | 來源出版物: | Applied Mathematical Modelling | 摘要: | The decline of trichloroethylene (TCE) in a metallic iron–water system results from the combination of reduction reaction and sorption onto iron surfaces. Sorption, particularly by highly impure iron, accelerates the removal of TCE from the aqueous phase, but delays the prevalence of steady-state conditions. In this case, an overly high value of reaction rate constant in the design of a treatment system would be used. In this work, the effects of an iron surface with 8.0% C, 6.1% O and 0.8% Si separately following HCl-washing and H2-reducing pretreatment on sorption and reduction rates were examined. The amounts of both aqueous and sorbed TCE were measured using a modified solventextraction method. TCE sorption onto an iron surface, as quantified by the Langmuir sorption maximum, followed the trend H2-reduced Fe04HCl-washed Fe04untreated Fe0 (0.887, 0.365 and 0.311 mg/g, respectively). Measurements of the concentration of sorbed TCE revealed that about 34–37% of the initial mass of TCE in the aqueous phase was removed by sorption by H2-reduced Fe0, 16–19% was removed by HCl-washed Fe0 and 13–16% was removed by untreated Fe0. A combination of new and previously reported data on cast iron’s capacity to sorb TCE revealed a linear relationship between this capacity and the C fraction in the surface of the iron, with the coefficient of determination (r2) exceeding 0.99. The first-order observed rate constants (kobs) of the reduction of TCE in contact with Fe0 were obtained from the slope of a plot of total TCE loss rate (dCT=dt) versus the amount of TCE in the aqueous phase (Cw) using linear least-squares analysis. The kobs values were 0.080, 0.148 and 0.191 h1 for untreated, HCl-washed and H2- reduced Fe0, respectively. Normalized to iron surface area concentration, the specific rate constants (kSA) were 2.37 103 , 2.31 103 and 5.62 103 h1m2 L, respectively. The results indicated that HCl-washing approximately doubled kobs, primarily because of the increase in the surface area of the iron, and it slightly decreased kSA due to rapid corrosion during the rinsing process. Both the number of reactive sites and the sorption capacity per unit iron surface area through the H2-reducing pretreatment were increased due to the reduction of iron oxide layer and the carbonization of carbon-containing subjects on the iron’s surface. Hence, the H2 reduction of cast iron promotes the removalof TCE from contaminated water by the concurrent sorption and reduction. r 2005 Elsevier Ltd. All rights reserved. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/2006111501244111 | 其他識別: | 246246/2006111501244111 | DOI: | 10.1016/j.apm.2005.05.001 |
顯示於: | 環境工程學研究所 |
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