Superfund Innovative Technology Evaluation (SITE)
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|Photoelectrocatalytic Degradation and Removal
of Organic and Inorganic Contaminants in Groundwaters
Photocatalytic oxidation offers a means of remediating low concentrations of organics in aqueous and air streams. Commercial development of this technology is limited by relatively low rates of oxidation of organics in aqueous systems and by fouling of the catalyst by other components of the waste stream. Results from this project indicate that applying an appropriate electric field across the photocatalyst extends the range of applications for this technology. The resulting "biased" photoelectrocatalytic reactor demonstrates ca. 40-60% higher rates of degradation of the test organic (25 ppm (as C) formic acid) than are observed in the corresponding non-biased reactor. However, the overall rate of reaction is still slow even when biased (a half-life of ca. 1 hour). This biased photoreactor successfully treated a waste containing both formic acid and dissolved copper. In addition, the biased photoreactor was not adversely affected by use in either relatively saline media or in media containing no dissolved oxygen. Non-biased photoreactors do not function under these conditions. Earlier studies of biased photoreactors employed photocatalysts coated on conductive glass. Because such photoelectrodes may not be commercially viable, photoelectrodes that were stable during repeated use were prepared for this project by coating the photocatalyst on a metallic substrate.