✍ Scribed by Claudio A. Zaror
No coin nor oath required. For personal study only.
Chemical oxidation and adsorption are feasible options to treat toxic effluents ; however, the lack of empirical design data impairs their implementation at industrial scale. This paper reports experimental results on a detoxiÐcation system based on enhanced oxidation using ozone in the presence of activated carbon. The study focuses on four representative model toxic phenolic compounds, i.e. 3-chlorophenol, 4-chlorophenol, 2-methoxyphenol, and pyrocatachol. The experimental system consisted of a 1É5 dm3 stirred reactor and an ozonizer with a mean production capacity of 0É1 mmol from pure O 3 s~1 oxygen. Adsorption and absorption processes were studied in the absence and presence of chemical reactions at pH 2, within the temperature range 15È35¡C and solid/liquid ratio 0É05È0É005 w/w. Results showed that all these contaminants are readily oxidized by ozone, with a pseudo-second order rate constant in the range 0É02È0É08 mmol~1 dm3 s~1 at pH2 and temperature 15È35¡C. Fast phenolic oxidation reactions at the gasÈliquid interphase increased the ozone absorption rate by a factor of 3È10, as compared with physical absorption only. The presence of activated carbon during ozonation signiÐcantly improved ozone selectivity. Adsorption isotherms and ozone self-decomposition data are also reported.
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