Abstract
The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol (2,4,6-TCP) in aqueous solution were investigated. The removal efficiency and the variation of HO, Cl, formic acid, and oxalic acid were studied during the semi-batch ozonation experiments (continuous for ozone gas supply, fixed volume of water sample). The results showed that when there was no scavenger, the removal efficiency of 0.1 mmol/L 2,4,6-TCP could reach 99% within 6 min by adding 24 mg/L ozone. The reaction of molecular ozone with 2,4,6-TCP resulted in the formation of HO. The maximal concentration of HO detected during the ozonation could reach 22.5% of the original concentration of 2,4,6-TCP. The reaction of ozone with HO resulted in the generation of a lot of OH° radicals. Therefore, 2,4,6-TCP was degraded to formic acid and oxalic acid by ozone and OH° radicals together. With the inhibition of OH°radicals, ozone molecule firstly degraded 2,4,6-TCP to form chlorinated quinone, which was subsequently oxidized to formic acid and oxalic acid. Two reaction pathways of the degradation of 2,4,6-TCP by ozone and O/OH° were proposed in this study.
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