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| 說明 | 249 p |
| 附註 | Source: Dissertation Abstracts International, Volume: 62-07, Section: B, page: 3334 |
| Chair: Bill Batchelor |
| Thesis (Ph.D.)--Texas A&M University, 2001 |
| The research on abiotic reductive dechlorination of chlorinated ethylenes by soil minerals and soil has been conducted to provide the fundamental knowledge that could be applied for the better operation of in-situ and ex-situ treatment processes and development of effective and cost-efficient remedial technologies |
| The reductive capacity of iron-bearing soil minerals and soil was an important characteristic to significantly affect degradation kinetics of target compounds. It appeared to be influenced by Fe(II) and reduced NOM in the soil minerals and soil. Iron-bearing soil minerals had consistent reductive capacities independent of contaminant type |
| Reductive dechlorination of chlorinated ethylenes by iron-bearing soil minerals and soil was characterized using batch reactors. The dechlorination kinetics of chlorinated ethylenes was properly described by a modified Langmuir-Hinshelwood kinetic model. Pyrite, GR<sub>SO4</sub>, and magnetite were more reactive than iron-bearing phyllosilicates but less reactive than Zn(0), mackinawite, and troilite in the reductive dechlorination of chlorinated ethylenes. The transformation products of chlorinated ethylenes were C hydrocarbons and chloride with small amounts of chlorinated intermediates, which suggests that the main transformation pathway for PCE, TCE, and c-DCE is reductive elimination and that for VC is hydrogenolysis. Fe(II) addition increased the reactivity of soil minerals indicating potential interactions between biotic and abiotic processes in reductive dechlorination. The corrected rate constants of TCE in GR<sub>SO4</sub> and biotite suspensions were independent of solid concentration and target organic concentration but influenced by pH and sorbed Fe(II).The sorption coefficients were independent of all factors but initial reductive capacities were significantly affected by them. The oxidation product of GR<sub> SO4</sub> during the reaction with TCE may be magnetite and/or maghemite |
| The application of abiotic reductive dechlorination of chlorinated ethylenes was demonstrated in soil suspensions. The dechlorination rates of chlorinated ethylenes by reduced soils were relatively similar to those by pyrite. C<sub> 2</sub> hydrocarbons and chloride were main transformation products by the reduced soils. The recoveries of TCE by reduced soils were constant during the five cycles of reduction/oxidation suggesting that semi-continuous use of the soils as reductants is possible. They decreased in the order: Fe(II) > dithionite > Fe(II) + dithionite indicating Fe(II) + dithionite treatment is most reactive |
| School code: 0803 |
| 主題 | Engineering, Environmental |
| Environmental Sciences |
| Geochemistry |
| 0775 |
| 0768 |
| 0996 |
| ISBN/ISSN | 0493313877 |
