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In Situ Electromigration as a Method for Removing Sulfate, Metals, and Other Contaminants from Ground Water
Author(s) -
Runnells Donald D.,
Wahli Catherine
Publication year - 1993
Publication title -
groundwater monitoring and remediation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 47
eISSN - 1745-6592
pISSN - 1069-3629
DOI - 10.1111/j.1745-6592.1993.tb00429.x
Subject(s) - cathode , copper , anode , electrolysis , electromigration , aqueous solution , sulfate , chemistry , adsorption , carbon fibers , metal , inorganic chemistry , analytical chemistry (journal) , electrode , environmental chemistry , metallurgy , materials science , composite material , composite number , organic chemistry , electrolyte
Electromigration is proposed as an in situ method for preconcentrating contaminants in ground water prior to pumping and treating. In earlier investigations by the senior author and co‐workers, it was found that Cu in synthetic ground water migrated strongly to a Pt cathode and plated out as metallic copper. In the present study, carbon electrodes were inserted into a laboratory column of fine quartz sand that was saturated with a lower concentration of CuSO 4 solution. A fixed potential of 2.5 V was applied, causing dissolved Cu and SO 4 to accumulate strongly at the cathode and anode, respectively. Only minor plating‐out of Cu took place on the carbon electrodes. In addition to the use of carbon electrodes, the present research also investigated the effects of a lower concentration of metal, accumulation of SO 4 adjacent to the anodes, adsorption of Cu on the sand, and competition by moving ground water. At an imposed voltage of 2.5 V and in the presence of 65 mg/L of dissolved Cu and 96 mg/L of SO 4 (0.001 M CuSO 4 solution), electrolysis of water caused large changes in the pH and speciation of the aqueous components, as well as precipitation of solid Cu‐hydroxides. Significant retardation of Cu occurred in the presence of ground water flowing at an average intergranular velocity of 0.2 m/day, but only minor retardation at water velocities of 1.9 and 2.9 m/day. Sulfate tends to migrate strongly to the anodes, suggesting that in situ electromigration may offer a useful new method for preconcentrating such highly soluble ions as SO 4 , NO 3 , and CI that are difficult to remove by conventional pump‐and‐treat methods. A number of potential problems exist that should be addressed in a field test.