Degradative stabilization of tetrachloroethene by zero valent zinc /
Experiments were conducted to investigate reduction of ics.
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: |
| Summary: | Experiments were conducted to investigate reduction of ics. tetrachloroethene (PCE) by zero valent metals using batch systems. Four zero valent metals (iron, zinc, aluminum, and copper) were tested for their reactivities for PCE in combination with two electron carriers (hematin and humid acid) to identify the most effective system. Further, the selected system was characterized to determine the optimum conditions for PCE removal and to understand the reaction pathways. The effectiveness of zero valent metals in degrading PCE when the systems were buffered (pH 6.4 - 7.9) was in the order: [] When the systems were no buffered (pH 6.7-9.2) the order was []. Hematin and humid acid were not observed to enhance the reaction rates. Comparing the rates of respective system, the zinc system was found to be the most effective in degrading PCE in the screening stage. In the characterization stage, zinc system was further investigated using the minimal head space method. Effects of hydroxyapatite [], a stabilizing agent, on PCE degradation was also studied. PCE primarily reacted to produce trichloroethylene (TCE), with trans-1,2- dichloroethylene (t-DCE) representing a minor product. Dechlorination of PCE was accelerated by the presence of hydroxyapatite, giving linear relationship between the observed reaction rate constants [] and hydroxyapatite loading when the degradation processes were assumed to follow first-order decay model. [] mostly generated from oxidative dissolution of zero valent zinc reacted with PCE, was effectively removed from the solution by hydroxyapatite. Ion substitution, coprecipitation, and adsorption are proposed as the main mechanisms for [] removal. All the three removal reactions appeared to be occurring simultaneously and the contribution of each mechanism to overall removal of [] was primarily dependent on hydroxyapatite loading, for a fixed amount of zero valent zinc. The results indicate that the use of hydroxyapatite in combination with conventional zero valent metals is promising in that the system can achieve simultaneous degradation of organic contaminants and stabilization of inorganic contaminants. |
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| Item Description: | Vita. "Major subject: Civil Engineering". |
| Physical Description: | ix, 61 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 55-60). |