Equilibrium and kinetics of aniline adsorption onto crosslinked sawdust-cyclodextrin polymers

A natural origin adsorbent was prepared by sawdust and beta-cyclodextrin (beta-CD) for the removal of an organic compound (aniline) during water pollution accidents. The results of BET, SEM and FTIR analyses indicated that beta-CD attaches on the sawdust surface and forms an organic film. Batch tests show that the optimum pH for aniline adsorption is in the range of 4-8. Adsorption equilibrium is achieved in 30 minutes, and the adsorption kinetics follows a pseudo-second-order kinetic model. The Langmuir model appears to fit the isotherm data better than the Freundlich model at 15 degrees C compared with that at 30 degrees C and 45 degrees C. The maximum adsorption capacity is estimated to be 84.03 mg g(-1) at 15 degrees C (R-2 > 0.99). The negative value of the standard entropy (Delta H degrees) and standard free energy (Delta G degrees) indicates an exothermic and spontaneous nature of the adsorption interaction. Moreover, the results of FTIR suggest that the formation of an inclusion complex between the b-CD and aniline molecules through host-guest interactions enhances the adsorption capability.