Adsorption of vitamin B_(12) to alumina, kaolinite, sand and sandy soil

摘要

Vitamin B_(12) is an important component of media used to stimulate the growth of many anaerobic microbes that dechlorinate aliphatic compounds. Its delivery to the subsurface is therefore a concern for enhanced in situ bioremediation and bioaugmentation. In situ circulation of vitamin B_(12) and a chemical reductant has also been field tested for treatment of chlorinated methanes, ethanes, and ethenes. The objective of this study was to determine the extent of B_(12) (added as cyanocobalamin) adsorption to aquifer solids. Batch studies indicated a minor amount of adsorption to kaolinite clay (Freundlich K_f = 1.5 (μg/g)(mL/μg)~(1) and 1 = 0.39) and sand (K_f = 0.70 (μg/g)(mL/μg)~(1) and l = 0.84), and no detectable adsorption to alumina. Column studies using a ~3H_2O tracer and vitamin B_(12) in distilled water (10μM) resulted in a B_(12) retardation factor (R) of approximately 2 for both sand (0.14% organic carbon) and a sandy soil (2.5% organic carbon). Using groundwater containing organic carbon (2.8mg/L) in place of distilled water did not significantly change R. The relatively low value for R indicates vitamin B_(12) can be distributed throughout a contaminated aquifer without experiencing significant losses to adsorption.