Vitamin B12 and Magnesium: a Healthy Combo for the Degradation of Trichloroethylene

Zero-valent magnesium (ZVMg), glacial acetic acid (GAA), and vitamin B12 were used to degrade trichloroethylene (TCE) in either pure anhydrous ethanol (EtOH) or 10% anhydrous EtOH in canola oil. Gas chromatography–mass spectrometry (GC–MS) was used to monitor the decrease in TCE concentration within each system over time. In pure anhydrous EtOH, a vitamin B12 concentration of 49.2 mg/L achieved the highest decrease in TCE concentration by 96 ± 0.4% (with lower vitamin B12 concentration, degradation was lower). Vitamin B12 and ZVMg also performed synergistically, increasing TCE degradation by approximately 78% relative to either ZVMg or vitamin B12 alone. In pure anhydrous EtOH, with ZVMg and vitamin B12, TCE was below detection after 2 h. Degradation products were likely volatile, as they were not detected in all liquid samples. Spectrophotometric analyses indicated the formation of the super reducing species of vitamin B12 (i.e., Co(I)) after 30 min in the presence of ZVMg, explaining the significant increase in TCE degradation. TCE degradation was also tested in 10% anhydrous EtOH in canola oil, with the purpose of developing a formulation for the in situ remediation of TCE-polluted aquifers. Canola oil would promote ZVMg contact with TCE, while mitigating its oxidation due to contact with groundwater. In 10% anhydrous EtOH in canola oil, the concentration of TCE decreased by approximately 40% within 30 min, with ZVMg alone. Our study provides the first proof of concept of an efficient in situ remediation method using environmentally friendly reagents, such as vitamin B12 and canola oil, for the degradation of TCE in polluted aquifers.