2-Chlorophenol oxidation by ultrasound/H₂O₂ in aqueous solution: Models and kinetics

The effect of varying reaction parameters on the decomposition of 2-chlorophenol (2-cp) and removal of total organic carbon (TOC) using the ultrasound/H₂O₂ process was investigated. The decomposition of 2-cp was found to be a first-order reaction. The experimental results showed that decomposition of 2-cp using the ultrasound/H₂O₂ process was more effective than that using the ultrasound or H₂O₂ alone. At pH 3, the efficiency of 2-cp decomposition was better than 99%, but that of TOC removal was only 63% after 360 min of reaction. We detected two intermediate compounds, i.e., 2-chloro-hydroquinone and 2-chloro-p-benzoquinone, during the reaction. With increasing ionic strength, the extent of 2-cp decomposition was remarkably enhanced. However, the removal of TOC was found to be nearly independent of the ionic strength. The extent of 2-cp decomposition was also enhanced by the addition of catalysts (FeSO₄, or Fe₂O₃/Al₂O₃), but this effect was insignificant compared with that of the addition of H₂O₂. The extent of 2-cp decomposition at a small initial concentration of 2-cp was more rapid than that at a greater one concentration.