Ultrasound Destruction of Aqueous 2-Chlorophenol in Presence of Silica and Peroxide

Abstract

This study investigate the potential of enhancing the sonochemical destruction of aqueous organics using silica and peroxide. The effect of solution pH, silica, and/or H₂O₂ with sonolysis was examined for destruction of 2-chlorophenol (2-CP). Sonochemical removal of 2-CP was higher at lower-solution pH (below the pKa of 2-CP). Presence of silica increased the removal rate by possibly creating more cavities for destruction of 2-CP. The optimum dosage of silica was 5 g/L. Sonolysis experiments were conducted with H₂O₂ dosages of 50, 75, and 100 mg/L. H₂O₂ dosage of 100 mg/L was observed to enhance 2-CP destruction by 27% in 60 min as compared to ultrasound alone. The optimum ratio of H₂O₂ to silica was 100 mg/L: 5 g/L and it increased destruction of 2-CP by almost twofold as compared to ultrasound alone. The chloride ion production increased with an increase in H₂O₂ dosage in the presence of silica. After 60 minutes of sonication, about 49% chloride ion production was observed in the presence of 5 g/L silica together with 100 mg/L H₂O₂. The percentage of destructed 2-CP that converted to chloride ions during ultrasound destruction of 2-CP was improved in the presence of silica and/or H₂O₂, as compared with ultrasound alone. Presence of silica and peroxide aids in enhancing conversion of destructed 2-CP to chloride ions, thereby reducing formation of chlorinated intermediate products. The kinetics study showed that silica and peroxide function independently and do not exhibit synergism during sonolysis.