Stable carbon isotope fractionation during trichloroethene degradation in magnetite-catalyzed Fenton-like reaction

Mineral-catalyzed Fenton-like oxidation of chlorinated ethylenes is an attractive technique for in situ soil and groundwater remediation. Stable carbon isotope enrichment factors associated with magnetite-catalyzed Fenton-like oxidation of trichloroethylene (TCE) have been determined, to study the possibility of applying stable carbon isotope analysis as a technique to assess the efficacy of remediation implemented by Fenton-like oxidation. The carbon enrichment factors (ε values) ranged from − 2.7‰ to − 3.6‰ with a mean value of − 3.3 ± 0.3‰, and only small differences were observed for different initial reactive conditions. The ε values were robust and reproducible, and were relatively insensitive to a number of environmental factors such as ratios of reactants and PCE co-contamination, which can reduce the uncertainty associated with application of isotope enrichment factors for quantification of in situ remediation by Fenton-like reaction. ε values for Fenton-like oxidation of TCE were intermediate in those previously reported for aerobic biological processes (ε = − 1.1 to − 20.7‰). Thus, field-derived ε values that are more negative than those for Fenton-like oxidation, may indicate the occurrence of aerobic biodegradation at contaminated sites undergoing in situ remediation with Fenton-like reaction. However, stable carbon isotope analysis is unable to determine whether there is the occurrence of biodegradation processes if field-derived ε values are less negative than those for Fenton-like oxidation.

► Carbon isotope fractionation during magnetite-catalyzed Fenton-like oxidation of TCE was determined. ► The enrichment factors range from − 2.7‰ to − 3.6‰ with a mean value of − 3.3‰ ± 0.3. ► The enrichment factor is relatively insensitive to a number of environmental factors.