Among the 275 substances on 2003 CERCLA Priority List of Hazardous Substances are included all the heavy metals. Thus, the effective remediation of contaminated sites for reuse must invariably address the efficient removal of heavy metals from solid materials and groundwater. The goal of this project is the development of two new ex-situ remediation technologies for contaminated sites, based on the application of spouted bed particulate electrodes to the removal of heavy metals from contaminated waters: (1) Spouted Bed Electrolytic Recovery (SBER) for electrowinning metals and metal mixtures; and (2) Spouted Bed Electrosorption/Desorption (SBED) for the electro-assisted adsorption of certain heavy metal compounds to improve the effectiveness of the use of activated carbon adsorbents by increasing their capacity and contaminant removal rates, so that less adsorbent is needed, and to reduce the current costs of thermal regeneration. This goal will be achieved by fulfilling the following Specific Aims:
Specific Aim 1 : Two new spouted bed cell systems will be constructed and developed: one for metal electrowinning (Spouted Bed Electrolytic Recovery, SBER), and the other for electrosorption/desorption of heavy metal compounds on activated carbon adsorbents (Spouted Bed Electrosorption/Desorption, SBED).
Specific Aim 2 : The SBER will be used to investigate and develop effective methods to recover multiple metals from solutions at high rates in the same device. This approach here will involve investigation of the electrochemistry and recovery of individual metals from a selected set of four (Cd, Cr, Cu and Ni) individual metals, successively building up to binary, ternary, and finally quaternary mixtures. This will also involve adaptation of new techniques, such as electrolytic recovery coupled with """"""""in-process precipitation"""""""" for high recovery rates.
Specific Aim 3 : The SBED system will be used to investigate and develop effective methods for the electro-assisted adsorption of certain heavy metal (As and Hg) compounds to improve removal rates from contaminated water, and to reduce the current costs of thermal regeneration of activated carbon adsorbents.
Specific Aim 4 : Numerical models of SBER and SBED systems, based on existing hydrodynamic models, and hydrodynamic and electrochemical data obtained from Tasks 1, 2, and 3 will be developed and used to explore scale-up strategies of laboratory systems to operating-scale systems.
Specific Aim 5. The culmination of the project will focus on recovery of selected metals from samples from contaminated sites obtained from groundwater and/or by leaching of contaminated soils containing mixtures of metals. Specific sources will be identified based uoon recommendations from oarticioants in our SBRP and RIDEM.
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