Catalytic Effects of Functionalized Carbon Nanotubes on Dehydrochlorination of 1,1,2,2-Tetrachloroethane
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- 作者：Weifeng Chen ; Dongqiang Zhu ; Shourong Zheng ; Wei Chen
- 刊名：Environmental Science & Technology
- 出版年：2014
- 出版时间：April 1, 2014
- 年：2014
- 卷：48
- 期：7
- 页码：3856-3863
- 全文大小：337K
- 年卷期：v.48,no.7(April 1, 2014)
- ISSN：1520-5851
文摘
The environmental implications of carbon nanomaterials have received much attention. Nonetheless, little is known about how carbon nanomaterials might affect the abiotic transformation of organic contaminants in aquatic environments. In this study, we observed that three functionalized multiwalled carbon nanotubes (MWCNTs)鈥攊ncluding a hydroxylated MWCNT (OH-MWCNT), a carboxylated MWCNT (COOH-MWCNT), and an aminated MWCNT (NH2-MWCNT)鈥攁ll had strong catalytic effects on the dehydrochlorination of 1,1,2,2-tetrachloroethane (TeCA) at three different pH (7, 8, and 9); notably, the most significant effects (up to 130% increase in reaction rate) were observed at pH 7, at which reaction kinetics was very slow in the absence of MWCNT. The primary mechanism was that the 鈭扤H2 group and the deprotonated 鈭扖OOH and 鈭扥H groups serve as bases to catalyze the reaction. Modeling results indicate that at any given pH the transformation kinetic constants of MWCNT-adsorbed TeCA were up to 2 orders of magnitude greater than the respective kinetic constant of dissolved TeCA. The overall catalytic effects of the MWCNTs depended both on the basicity of the surface functionalities of MWCNT and on the adsorption affinities of MWCNT for TeCA. Interestingly, Suwannee River humic acid鈥攕elected as a model dissolved organic matter鈥攈ad negligible effects on the dehydrochlorination kinetics, even though it is rich in surface O-functionalities. An important environmental implication is that carbon nanotubes released into the environment might significantly affect the fate of chlorinated solvents.