Electrochemical oxidation of 1,4-dioxane at boron-doped diamond electrode

BACKGROUND: The electrochemical oxidation of 1,4-dioxane at a boron doped diamond (BDD) surface on a niobium substrate anode was studied because (i) 1,4 dioxane is a resistant contaminant in waste-waters and ground-waters which needs to be removed/oxidized and (ii) most of the currently applied techniques for removal/oxidation require chemicals. RESULTS: Results show that in the potential region supporting electrolyte stability 1,4-dioxane can be oxidized directly. Adhesive products, which cause electrode fouling, are also formed during oxidation in this potential region. The BDD anode can be restored to its initial activity by simple anodic treatment in the potential region of electrolyte decomposition. In this region, oxidation reactions leading to complete oxidation of 1,4-dioxane, can take place due to electro-generated\ hydroxyl radicals. Therefore, dioxane can only be effectively oxidized at these potentials. The effect of current density on the oxidation of 1,4-dioxane has been investigated. The experimental results have also been compared with a theoretical chemical oxygen demand (COD)-instantaneous current efficiency (ICE) model. At a current density above 32 mA cm(-2), the oxidation process is completely controlled by mass transfer and no intermediates are formed. 92% of the COD can be removed with a total consumption of 7 Ah L-1. CONCLUSIONS: Results show that dioxane can be effectively and completely oxidized at a BDD anode. (C) 2010 Society of Chemical Industry