Comparison of various organic compounds destruction on rare earths doped Ti/Sb-SnO₂ electrodes

Ti/Sb-SnO₂ and three kinds of rare earths (REs), namely Ce, Gd, and Eu doped Ti/Sb-SnO₂ electrodes were prepared and tested for their capacity on electrocatalytic degradation of three kinds of basal aromatic compounds (benzoquinone, hydroquinone and catechol) and six kinds of aliphatic acids (maleic acid, fumaric acid, succinic acid, malonic acid, oxalic acid and acetic acid). The elimination of selected organics as well as their TOC removal with different doped Ti/Sb-SnO₂ electrodes was described by first-order kinetics. Compared with Ti/Sb-SnO₂, the Gd and Eu doped electrodes show better performance on the degradation of most of the selected organics, while Ce doped electrode shows either closely or lower efficiency on the degradation of these selected organics. Besides electrode material, the molecular structure of organic compound has obvious effect on its degradation in the electrocatalytic process. Catechol is more resistant to the electrophilic attack by hydroxyl radicals than benzoquinone and hydroquinone. The compound with more complicate molecular structure or longer carbon chain is more difficult to be mineralized. The aliphatic acid with higher oxygen content or more double bonds is more readily to be oxidized in the electrocatalytic process.