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

Zero-valent magnesium (ZVMg), glacial acetic acid (GAA), and vitamin B 12 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 B 12 concentration of 49.2 mg/L achieved the highest decrease in TCE concentration by 96 ± 0.4% (with lower vitamin B 12 concentration, degradation was lower). Vitamin B 12 and ZVMg also performed synergistically, increasing TCE degradation by approximately 78% relative to either ZVMg or vitamin B 12 alone. In pure anhydrous EtOH, with ZVMg and vitamin B 12 , 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 B 12 (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 B 12 and canola oil, for the degradation of TCE in polluted aquifers. Graphical abstract