Effects of surface termination of boron-doped diamond anodes on oxidation of aqueous compounds

Electrochemical oxidation using boron-doped diamond (BDD) electrodes is widely being studied as an alternative to other advanced oxidation processes (AOPs). However, recent work in our laboratories indicates that the oxidation of chloride-containing waters with BDD electrodes results in toxic perchlorate (ClO4-) production, where the rate-determining step is the oxidation of chlorate (ClO3 -) to ClO3-. ClO3- is first oxidized on the electrode surface via direct electron transfer (DET) to form the chlorate radical (ClO3*). ClO3 * then reacts with hydroxyl radicals (OH*) to form ClO4-, which is mediated by functional groups at the electrode surface. Thus, work presented in this thesis focuses on effect of electrode functional groups (e.g., C-H, C-OH, C-F) on both rates of organic compound oxidation and ClO4- formation. Batch and cyclic voltammetry experiments, along with XPS analysis were used to understand the relationship between reactivity and surface functional groups. Results indicate that ClO4- formation is limited on electrodes with a high density of C-OH as well as C-F groups. Research also focused on organic compound oxidation to illustrate a relationship between electrode functional groups and organic compound oxidation rates. Results indicate organic compound oxidation rates remained constant with a change in surface functional group.