Abiotic reduction of aquifer materials by dithionite: A promising in-situ remediation technology
- Pacific Northwest Lab., Richland, WA (United States)
- Whitman College, Walla Walla, Washington, DC (United States)
Laboratory batch and column experiments were conducted with Hanford sediments to develop the capability to predict (1) the longevity of dithionite in these systems, (2) its efficiency as a reductant of structural iron, and (3) the longevity and reactivity of the reduced iron with soluble inorganic and organic species. After an initial induction period, the loss of dithionite by disproportionation and oxidation could be described by pseudo-first-order (PFO) kinetics. Other than the initial reaction with ferric iron, the primary factor promoting loss of dithionite in this system was disproportion nation via heterogeneous catalysis at mineral surfaces. The efficiency of the reduction of structural iron was nearly 100% for the first fourth of the ferric iron, but declined exponentially with higher degrees of reduction so that 75% of the ferric iron could be reduced. This decrease in reduction efficiency probably was related to differences in the accessibility of ferric iron in the mineral particles, with iron in clay-sized particles being the most accessible and that in silt- and sand-sized particles less accessible. Flow-through column studies showed that a reduced-sediment barrier created in this manner could maintain a reducing environment.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 43791
- Report Number(s):
- PNL-SA-24505; CONF-941124-22; ON: DE95007812; TRN: 95:010878
- Resource Relation:
- Conference: 33. Hanford symposium on health and the environment: symposium on in-situ remediation--scientific basis for current and future technologies, Richland, WA (United States), 7-11 Nov 1994; Other Information: PBD: Nov 1994
- Country of Publication:
- United States
- Language:
- English
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