Removal of 2,4-dichlorophenol using cyclodextrin-ionic liquid polymer as a macroporous material: Characterization, adsorption isotherm, kinetic study, thermodynamics

Cyclodextrin-ionic liquid polymer (pCD-BIMOTs-TDI) was firstly synthesized using functionalized beta-Cyclodextrin (CD) with 1-benzylimidazole (BIM) to form monofunctionalized CD (beta CD-BIMOTs) and was further polymerized using toluene diisocyanate (TDI) linker to form insoluble beta CD-BIMOTs-TDI. SEM characterization result shows that beta CD-BIMOTs-TDI exhibits macropore size while the BET result shows low surface area (1.254 m(2) g(-1)). The unique properties of the ILs allow us to produce materials with different morphologies. The adsorption isotherm and kinetics of 2,4-dichlorophenol (2,4-DCP) onto beta CD-BIMOTs-TDI is studied. Freundlich isotherm and pseudo-second order kinetics are found to be the best to represent the data for 2,4-DCP adsorption on the beta CD-BIMOTs-TDI. The presence of macropores decreases the mass transfer resistance and increases the adsorption process by reducing the diffusion distance. The change in entropy (Delta S degrees) and heat of adsorption (Delta H degrees) for 2,4-DCP on pCD-BIMOTs-TDI were estimated as -55.99 J/Kmol and -18.10 J/mol, respectively. The negative value of Gibbs free energy (Delta G degrees) indicates that the adsorption process is thermodynamically feasible, spontaneous and chemically controlled. Finally, the interactions between the cavity of beta CD-BIMOTs and 2,4-DCP are investigated and the results shows that the inclusion of the complex formation and pi-pi interaction are the main processes involved in the adsorption process. (C) 2013 Elsevier B.V. All rights