Electrochemical capabilities in both photoreduction and detection of toxic Cr(VI) pollutant

Chromium is widely used in several industrial processes such as metal plating, leather tanning, paint making and others. Due to its acute toxicity, carcinogenic action and high mobility in water, Cr(VI) is in the list of priority pollutants of most countries. In aquatic environments, chromium is present mostly as hexavalent Cr(VI) and trivalent Cr(III). Cr(III) is less noxious and usually immobile through precipitation or adsorption onto solid phase. Therefore, the rapid and accurate monitoring of both chromium species and the efficient reduction of Cr(VI) to Cr(III) in contaminated waters are highly desirable. Specifically, Cr(VI) ions in water can be completely photoreduced to Cr(III) at the surface of UV-excited TiO2 photocatalysts. The transfer of photocatalytic results from slurry to immobilized particles on substrates is a general concern, primarily due to the elimination of filtration steps. Thus, the first part of this presentation is focused on the electrophoretic deposition (EPD) of TiO2 as an alternative procedure to deposit the oxide in dense layers, avoiding slurry filtration steps. The second part of the presentation will be devoted to the study of the photocatalytic performances of titania layers by comparing traditional polarographic techniques with a new environmentally friendly electroanalytical approach based on the use of bismuth screen printed electrodes.