Surface sulfidated zero-valent iron [Fe(0)] particles represent a promising engineered approach for the degradation of chlorinated organic contaminants in groundwater.  However, naturally occurring iron sulfide minerals can also enable reductive dechlorination.  Although both types of solids can be formed via abiotic or biologically mediated pathways, studies to date have focused on solids produced chemically.  This study aims to compare the activity of biologically produced, surface sulfidated Fe(0) particles to the activity of iron sulfide solids formed from the precipitation of ferrous iron with biologically derived free sulfide.  Experiments will utilize Desulfovibrio desulfuricans, a model sulfate-reducing bacteria, for sulfide production. Experiments will be conducted in two stages.  First, iron (zero valent or ferrous iron in solution) will be exposed to solutions of biologically produced sulfides.  The resulting particles will be characterized for the following properties:  diameter, specific surface area, extent of sulfidation (surface coverage and depth), and overall morphology. Following particle synthesis, particles will be exposed to trichloroethylene (TCE), a model chlorinated contaminant. Concentrations of TCE and daughter products of dechlorination will be monitored over time, and rates of dechlorination activity will be calculated. This work overall will evaluate the effectiveness of biological sulfidation of an anthropogenic surface [Fe(0)] for TCE dechlorination, and compare it with TCE attenuation via the natural process of biologically-mediated iron sulfide formation .

Dechlorination reactivity of biologically derived iron sulfide and sulfidated zero-valent iron particles

255th National Meeting (2018)

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