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Reductive dechlorination of carbon tetrachloride with elemental iron
Journal article   Peer reviewed

Reductive dechlorination of carbon tetrachloride with elemental iron

Bradley R Helland, Pedro J.J Alvarez and Jerald L Schnoor
Journal of Hazardous Materials, Vol.41(2-3), pp.205-216
1995
DOI: 10.1016/0304-3894(94)00111-S

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Abstract

Carbon tetrachloride (CCl 4 ) was abiotically dechlorinated to chloroform (CHCl 3 ) and methylene chloride (CH 2 Cl 2 ) by zero valent iron (Fe 0 ). Dechlorination of CCl 4 was rapid, and approximately followed first-order kinetics in the range of concentrations tested (CCl 4 : 1.5–5.5 μ M ; Fe 0 powder: 1–10 g per 265 ml distilled water). Initial dechlorination rate coefficients for anoxic batch reactors (0.290 ± 0.009 h −1 for 1 g Fe 0 ; 1.723 ± 0.078 h −1 for 10 g Fe 0 ) increased with iron surface area (initially 2.4 ± 0.2 m 2 /g). Rate coefficients also increased with time, probably because of an increase in reactive surface area due to cathodic depolarization and pitting of the iron surface. Dechlorination also occurred under oxic conditions, although the rates were significantly slower (e.g., 0.085 ± 0.041 h −1 for 1 g Fe 0 and initial dissolved oxygen 7.4 mg/l). A rapid pH increase was synchronous to dissolved oxygen consumption, and the pH remained constant after the oxygen was depleted. This was attributed to the proton and oxygen consuming aerobic corrosion of the Fe 0 surface. The potential for developing remediation technology with Fe 0 is discussed.

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