Enhanced oxidation of toxic effluents using simultaneous ozonation and activated carbon treatment

Zaror C.A.

Keywords: temperature, kinetics, oxidation, adsorption, water, detoxification, management, absorption, effluent, treatment, mass, ph, phenols, carbon, ozone, ozonation, impurities, phenol, article, isotherms, waste, chlorophenol, guaiacol, catechol, derivative, chemical, Materials, Reaction, Transfer, activated, Hazardous, Enhanced

Abstract

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 detoxification 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 1.5 dm3 stirred reactor and an ozonizer with a mean production capacity of 0.1 mmol O3 s-1 from pure oxygen. Adsorption and absorption processes were studied in the absence and presence of chemical reactions at pH 2, within the temperature range 15-35°C and solid/liquid ratio 0.05-0.005 w/w. Results showed that all these contaminants are readily oxidized by ozone, with a pseudo-second order rate constant in the range 0.02-0.08 mmol-1 dm3 s-1 at pH2 and temperature 15-35°C. Fast phenolic oxidation reactions at the gas-liquid interphase increased the ozone absorption rate by a factor of 3-10, as compared with physical absorption only. The presence of activated carbon during ozonation significantly improved ozone selectivity. Adsorption isotherms and ozone self-decomposition data are also reported. 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 detoxification 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 1.5 dm3 stirred reactor and an ozonizer with a mean production capacity of 0.1 mmol O3 s-1 from pure oxygen. Adsorption and absorption processes were studied in the absence and presence of chemical reactions at pH 2, within the temperature range 15-35°C and solid/liquid ratio 0.05-0.005 w/w. Results showed that all these contaminants are readily oxidized by ozone, with a pseudo-second order rate constant in the range 0.02-0.08 mmol-1 dm3 s-1 at pH2 and temperature 15-35°C. Fast phenolic oxidation reactions at the gas-liquid interphase increased the ozone absorption rate by a factor of 3-10, as compared with physical absorption only. The presence of activated carbon during ozonation significantly improved ozone selectivity. Adsorption isotherms and ozone self-decomposition data are also reported.

Más información

Título de la Revista: JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
Volumen: 70
Número: 1
Editorial: Wiley
Fecha de publicación: 1997
Página de inicio: 21
Página final: 28
URL: http://www.scopus.com/inward/record.url?eid=2-s2.0-0031239332&partnerID=q2rCbXpz