Adsorptive removal of cationic surfactants from aqueous solutions onto high-area activated carbon cloth monitored by in situ UV spectroscopy

Activated carbon cloth (ACC) was used as adsorbent for the removal of cationic surfactants such as benzyltrimethylammonium chloride (BTMACl), benzyltriethylammonium chloride (BTEACl), benzyltributylammonium chloride (BTBACl), benzyldimethyldecylammonium chloride (BDMDACl), benzyldimethyltetradecyl ammonium chloride (BDMTDACl), benzyldimethylhexadecylammonium chloride (BDMHDACl), N-dodecylpyridinium chloride (N-DPCl) and N-cetylpyridinium chloride (CPCl) from aqueous solutions. The adsorption efficiency of the ACC was evaluated for cationic surfactants. Adsorption process was followed by in situ UV spectroscopic technique. The kinetic data, so obtained, were treated according to the pseudo first-order, the pseudo second-order, the Elovich and the intraparticle diffusion models in order to understand the adsorption mechanism of cationic surfactants onto the ACC. The best fit was found with the pseudo second-order model. The experimental isotherm data were obtained at 30 degrees C and analyzed by the Freundlich and the Langmuir models. The parameters of isotherm equations were determined. The Freundlich model was found to represent the experimental data better than the Langmuir model. The observed adsorption behaviors are discussed in terms of the pH of the solution, the nature of cationic surfactants (e.g. functional groups, size, and hydrophobicity) and the nature of the ACC (e.g. surface charge, pore size). A fair linear correlation was found between some adsorption parameters and apparent molar volumes at infinite dilution for benzyltrialkylammonium chlorides. (C) 2009 Elsevier B.V. All rights reserved.