Enhanced Dechlorination of Tetrachloroethylene by Zerovalent Silicon in the Presence of Polyethylene Glycol under Anoxic Conditions

Lee, Chun-Chi; Doong, Ruey‐an

doi:10.1021/es1030273

Cited by 12 publications

(4 citation statements)

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“…Interestingly, results displayed in Figure 10 show that the k obs for PCE dechlorination is 1.5 times higher than that of CTAB and more than 100 times higher than that by Si alone, clearly indicating that the addition of PEG can effectively enhance the dechlorination efficiency and rate of chlorinated hydrocarbons. (38).…”

Section: The Enhancement Methods By the Addition Of Surfactantsmentioning

confidence: 99%

“…Liu et al (43) proposed an idea to preserve the reductive ability by terminating the formation of H 2 in zerovalent iron system, which could increase the dechlorination rate of chlorinated hydrocarbons and keep the benefit for long-term usage. Interestingly, addition of PEG also can prevent the formation of SiO 2 onto the surface of zerovalent iron, leading to the acceleration of dechlorination efficiency and rate of PCE (38). To further examine the effect of PEG on the formation of silicon dioxide, various loadings of PEG ranging between 0.01 and 0.6 μM were added into Si-H 2 O system.…”

Section: The Enhancement Methods By the Addition Of Surfactantsmentioning

confidence: 99%

Section: The Enhancement Methods By the Addition Of Surfactantsmentioning

confidence: 99%

Section: The Enhancement Methods By the Addition Of Surfactantsmentioning

confidence: 99%

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Application of Zerovalent Silicon for the Dechlorination of Chlorinated Hydrocarbons – A Review

Lee

Doong

2013

ACS Symposium Series

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The dechlorination of chlorinated hydrocarbons by zerovalent metals has received much attention. In addition to iron, zerovalent silicon is a strong reductive material which can serve as an alternative for remediation of contaminated sites. However, little is known about the reaction kinetics and mechanism of chlorinated hydrocarbons by zerovalent silicon under anoxic conditions. In this review, parameters controlling the reactivity of silicon in dechlorination were discussed. In addition, the enhanced effects of bimetallic system including Fe/Si and Ni/Si and addition of surfactant on the dechlorination kinetics and mechanisms were also introduced and reviewed. The dechlorination efficiency and rate of chlorinated hydrocarbons by zerovalent silicon increased upon increasing pH from 7.2 to 9.5. The dechlorination followed the pseudo-first-order kinetics and the rate constant (k obs ) for carbon tetrachloride dechlorination increased from 0.5 h -1 at pH 7.2 to 2.11 h -1 at pH 9.5. In addition, tetrachloroethylene (PCE) can be effectively dechlorinated by zerovalent silicon. Addition of Ni 2+ and Fe 2+ significantly enhanced the dechlorination efficiency and rate of PCE as well as changed the distribution of products. However, the roles of Ni 2+ and Fe 0 were different. Addition of Fe 0 to Si could form the buffer solution to maintain the pH at 7.8 when the ratio of Si and Fe is optimized, and subsequently enhanced the dechlorination efficiency and rate of carbon tetrachloride and PCE, while the adsorbed Ni(II) In Interactions of Nanomaterials with Emerging Environmental Contaminants; Doong, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2013.ions were converted to Ni(0) homogeneously onto the surface of zerovalent silicon and exhibited the synergistic effect on the dechlorination of PCE by Si under anoxic conditions. In addition, the introduction of surfactant can also enhance the dechlorination efficiency, and the dechlorination rate of PCE increased 62 and 106 times higher than silicon alone when CTAB and polyethylene glycol were introduced, respectively. X-ray photoelectron spectroscopy results confirmed that the addition of PEG could inhibit the production of silicon dioxide, resulting in the acceleration of dechlorination rate of PCE by Si. These processes would significantly accelerate the dechlorination rate of chlorinated hydrocarbons under anoxic conditions and would be helpful in facilitating the development of processes that could be useful for the enhanced degradation of co-contaminants for long-term performance. 212Downloaded by UNIV LAVAL on December 1, 2014 |

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Section: The Enhancement Methods By the Addition Of Surfactantsmentioning

confidence: 99%

Section: The Enhancement Methods By the Addition Of Surfactantsmentioning

confidence: 99%

Section: The Enhancement Methods By the Addition Of Surfactantsmentioning

confidence: 99%

Section: The Enhancement Methods By the Addition Of Surfactantsmentioning

confidence: 99%

See 2 more Smart Citations