Monitoring heavy metals in seawater by their electrochemically induced deposition as hydroxides.

Citation:

Michael Eldan, Shoham, Tamar , Erel, Yigal , and Mandler, Daniel. . 2009. “Monitoring Heavy Metals In Seawater By Their Electrochemically Induced Deposition As Hydroxides.”. Electroanalysiselectroanalysis, 21, Pp. 368 - 378.

Abstract:

A novel method for monitoring heavy metals in seawater is presented. The method is based on the electrochem. codeposition of metal hydroxides driven by the change of pH at the surface of a gold electrode. Altering the pH is achieved by applying a neg. potential or current that reduces the water and thereby increases the concn. of hydroxyl ions. This, in turn, causes metals to coppt. with Mg(OH)2. The continuous deposition enriches the ppt. with the metals (as compared with their concn. in the aq. phase) and allows their detn. by ICP-MS upon dissolving the deposit. A set of expts. in which seawater was spiked with 1-10 ppm of Cu, Cr, Co, Zn and Pb, was conducted. It was obsd. that metals were accumulated in the ppt. as a function of time and their concn. in seawater. The ppts. were analyzed by SEM, EDS and XPS indicating that the metal hydroxides formed a sep. phase from Mg(OH)2 and even water electroreducible metals, e.g., Cu2+, preferentially pptd. as hydroxides. Distribution consts. correlating the concns. of the metals in the deposited salts to their concns. in seawater were calcd. These calcns. imply that the mechanism governing the pptn. of the metal hydroxides by the electrochem. induced process is likely to be kinetically and mass-transport driven rather than thermodynamically controlled. [on SciFinder(R)]