Heterogeneity of polymer-based active carbons in adsorption of aqueous solutions of phenol and 2,3,4-trichlorophenol

Heterogeneity effects that accompany adsorption of phenolic compounds from water by polymer-based activated carbons are investigated at different values of solution pH. Activated carbons prepared from poly(ethylene terephthalate) and polyacrylonitrile (APET and APAN, respectively) were used to adsorb phenol and 2,3,4-trichlorophenol in acidic (pH = 3), unbuffered, and basic (pH = 11) aqueous solutions. A Langmuir-Freundlich adsorption-isotherm equation was used to estimate the parameters that characterize adsorption of phenols from dilute solutions on heterogeneous surfaces. Adsorption energy distribution functions were calculated by a regularization method. Analysis of these functions for the APET and APAN carbons provides comparative information about their heterogeneity.