Abstract

The rate and equilibrium retention of pentachlorophenol, in an aqueous medium, by activated carbons obtained from peach stones and Eucalyptus globulus chips are studied and related to the chemical and textural properties of the adsorbents. E globulus-activated carbons exhibited a higher pentachlorophenol initial retention rate, due to the higher contribution of the macropores to the porosity of these materials. However, the pentachlorophenol retention rate in activated carbons from peach stones increases to a greater extent than in E globulus with the burn-off growth, due to the greater development of mesopores in the former. Under the experimental conditions used, the initial retention rate of pentachlorophenol in both adsorbents showed a mixed chemical and diffusional dependence, and the most important variables are the particle size of the adsorbents and the temperature of the medium. Pentachlorophenol equilibrium retention capacity depends on the apparent specific surface area, the presence of carbonylic-like surface functional groups and the accessibility of the adsorbate to the adsorption sites. The dependence of pentachlorophenol retention capacity with the surface concentration of carbonylic functional groups suggests some chemical interactions between the aromatic pentachlorophenol ring and the carbonylic-like surface functional groups present in the activated carbons. The rate and equilibrium retention of pentachlorophenol, in an aqueous medium, by activated carbons obtained from peach stones and Eucalyptus globulus chips are studied and related to the chemical and textural properties of the adsorbents. E globulus-activated carbons exhibited a higher pentachlorophenol initial retention rate, due to the higher contribution of the macropores to the porosity of these materials. However, the pentachlorophenol retention rate in activated carbons from peach stones increases to a greater extent than in E globulus with the burn-off growth, due to the greater development of mesopores in the former. Under the experimental conditions used, the initial retention rate of pentachlorophenol in both adsorbents showed a mixed chemical and diffusional dependence, and the most important variables are the particle size of the adsorbents and the temperature of the medium. Pentachlorophenol equilibrium retention capacity depends on the apparent specific surface area, the presence of carbonylic-like surface functional groups and the accessibility of the adsorbate to the adsorption sites. The dependence of pentachlorophenol retention capacity with the surface concentration of carbonylic functional groups suggests some chemical interactions between the aromatic pentachlorophenol ring and the carbonylic-like surface functional groups present in the activated carbons.