The adsorption from the aqueous solution of environmentally relevant phenol and 2,3,4-trichlorophenol was studied on activated carbon prepared from polyethyleneterephthalate (burn-off 50 %). Buffered (pH=3 and 11) and nonbuffered solutions were applied. The adsorption was governed by the surface chemistry of the carbon, as it has a relatively high oxygen content. The adsorption mechanism was found to depend both on the pKa of the phenols and the pH of the solution, as the latter influences the surface chemistry of the carbon as well. In the case of the phenol, the solute and the solvent molecules compete for the surface sites, as the dispersion forces arising between the π electrons in phenol and π electrons in carbon as well as the electron-donor - acceptor interactions between the basic surface oxygen groups and the aromatic ring are weak. The halogen substitution in the trichlorophenol significantly increases the strength of these interactions. The competitive adsorption of water takes place only at high pH, where the adsorption of the trichlorophenol is hindered by electrostatic repulsion. In non-buffered medium the trichlorophenol is adsorbed by a specific interaction, as it can be concluded from the enormously high value of the adsorption equilibrium constant.
|Translated title of the contribution||Adsorption from aqueous phenol and 2,3,4-trichlorophenol solutions on polymer based activated carbon|
|Journal||Magyar Kemiai Folyoirat, Kemiai Kozlemenyek|
|Publication status||Published - Mar 2001|
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