Analysis of the adsorption isotherms of a non-ionic surfactant from aqueous solution onto activated carbons

The adsorption isotherms at 20 degreesC onto four activated carbons of the non-ionic surfactant Triton X-100 from aqueous solution have been studied over a wide concentration range. The adsorption was explained using one or a combination of two Langmuir equations, depending on the equilibrium concentration range studied. A description of the adsorbed layer was constructed on the basis of the information obtained from the isotherms and assuming the model of van Oss et al. for the interfacial interaction between adsorbent and adsorbate. The results indicate that there are at least two kinds of interactions, the first related to a direct interaction between the activated carbon surface and adsorbate molecules, and the second mainly due to the interaction between surfactant molecules at the adsorbent-solution interface leading to the formation of interfacial aggregates. (C) 2001 Elsevier Science Ltd. All rights reserved.