Abstract

Recently, the electrochemical oxidation of refractory organic materials has received significant research attention. In this research, titanium electrodes coated with iridium and tin were prepared using pyrolysis and dip-coating, respectively, and the surface and chemical composition of the fabricated electrodes were determined using scanning electron microscopy and X-ray diffraction analysis. Following this, the elimination routes for the contaminants in phenol wastewater treated with the fabricated electrodes were examined. Phenols have complex degradation mechanisms making it difficult to determine their reaction pathways and produce stable discharge concentrations. In the electrochemical oxidation of phenols, several intermediate species such as benzoquinone and carboxylic acids are produced. Benzoquinone is known to be more harmful to the ecosystem than carboxylic acids. Therefore, in the present study, the partial degradation of phenols was investigated under electrochemical anodic oxidation in the presence of NaCl during wastewater treatment using the Ti/SnO<sub>2</sub> and Ti/IrO<sub>2</sub>. electrodes. The presence of NaCl in the electrolyte catalyzed the oxidation of phenols only with the Ti/IrO<sub>2</sub> anode. This catalytic action of NaCl was attributed to the participation of electro generated ClO<sup>-</sup> in the oxidation of phenols and their oxidation products near to the anode or/and in the bulk of the electrolyte. The phenol removal rate was excellent when the phenol concentration was low and the electrolyte concentration and cell potential were higher. In particular, the removal rate was 99.8% after 30 min when the phenol and electrolyte concentrations were 1,000 mg/L and 0.4%, respectively. The reaction velocity of electrolysis exhibited first order for the phenol concentration.

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