Efficient Dechlorination of Carbon Tetrachloride by Hydrophobic Green Rust Intercalated with Dodecanoate Anions

The reductive dechlorination of carbon tetrachloride (CT) by FeII–FeIII hydroxide (green rust) intercalated with dodecanoate, FeII4FeIII2(OH)12(C12H23O2)2·yH2O (designated GRC12), at pH ∼ 8 and at room temperature was investigated. CT at concentration levels similar to those found in heavily contaminated groundwater close to polluted industrial sites (14–988 μM) was reduced mainly to the fully dechlorinated products carbon monoxide (CO, yields >54%) and formic acid (HCOOH, yields >6%). Minor formation of chloroform (CF), the only chlorinated degradation product, was also detected (yields <6.3%). Reactions carried out with excess GR followed pseudo first-order kinetics with respect to CT with rate constants ranging from 6.5 × 10–2 to 0.47 h–1. These rate constants are comparable to those measured for CT dechlorinations mediated by zerovalent iron. Reduction of the highest concentration of CT (1.4 mM) proceeds until 56% of the FeII sites of GRC12 was consumed. This reaction ceased after 10 h due to surface passivation of GRC12.