Electrochemical Reduction of Hexavalent Chromium on Glassy Carbon Electrodes in Acidic Buffers

As fresh water systems become endangered due the expansion of growth and human civilization, it is important to find effective water purification strategies. A common water contaminant that is mostly generated through industrial processes is hexavalent chromium. The two stable forms of chromium found in aqueous systems are hexavalent chromium, Cr(VI), and trivalent chromium, Cr(III). Considered an essential nutrient, Cr(III) is non-toxic to humans. Cr(VI) on the other hand, is toxic at low concentrations and can be ingested through drinking contaminated water. There is no standard limit to the amount of Cr(VI) that can be in drinking water and most recommended limits are for the total chromium species. Although there are current remediation methods for Cr(VI), they are usually expensive and generate large amounts of waste. Electrochemical methods are attractive for water purification as due to high sensitivity and low waste generation. While research has been collected on many electrode substrates, there is a noticeable lack in the data collected on glassy carbon electrodes for the reduction of Cr(VI). This dissertation will focus on the fundamental chemistry for the reduction of Cr(VI) at the bare surface of glassy carbon electrodes in acidic buffers. The dependence of protons and the effect pH has on the reduction will be observed and compared to literature precedents. The effect of buffer properties have on Cr(VI) reduction will be examined in order to create an environment for efficient reduction. This will lead into utilizing electrocatalysts as electron and proton mediators to decrease the overpotential required for Cr(VI) reduction. Lastly, there will be a discussion on the future outlooks and directions for the research of Cr(VI) reduction on glassy carbon electrodes