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Dehydrochlorination of activated carbon-bound 1,1,2,2-tetrachloroethane: Implications for carbonaceous material-based soil/sediment remediation.
- Source :
-
Carbon . Nov2014, Vol. 78, p578-588. 11p. - Publication Year :
- 2014
-
Abstract
- Carbonaceous materials such as activated carbon (AC) are effective adsorbents for a number of organic contaminants, and are often used in soil and sediment remediation to sequester organic contaminants. However, little is known about the abiotic reactivity (and thus, the long-term fate) of the carbonaceous material-bound contaminants. We studied the base-promoted dehydrochlorination kinetics of low-level (~1.25mg/g) 1,1,2,2-tetrachloroethane (TeCA) adsorbed to 17 different ACs varying in origin and physicochemical properties. Activated carbon-bound TeCA exhibited significant reactivity--at a given pH the apparent reaction kinetic constants of AC-bound TeCA are 13-70% of the respective kinetic constants of dissolved TeCA. Binding to ACs likely have affected the reactivity of TeCA via two important mechanisms. First, the deprotonated surface O-functional groups (e.g., carboxyl and phenolic groups) catalyzed the base-promoted dehydrochlorination reaction by serving as the conjugate bases. Second, at low contaminant loadings TeCA molecules likely resided primarily in the micropores of ACs (particularly, micropores with diameters of 0.67-1.6nm), wherein mass transfer of OH- (the nucleophile that reacts with TeCA) was inhibited. An important environmental implication is that carbonaceous materials not only sequester contaminants, but also allow contaminants to be slowly degraded in situ. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00086223
- Volume :
- 78
- Database :
- Academic Search Index
- Journal :
- Carbon
- Publication Type :
- Academic Journal
- Accession number :
- 97448498
- Full Text :
- https://doi.org/10.1016/j.carbon.2014.07.041