Selective adsorption of L-TA/D-TA by β-cyclodextrin derivative modified with l-tryptophan: Isotherm, kinetic and thermodynamics studies

β-Cyclodextrin derivative modified with l-tryptophan (L-Trp-CD) was prepared for recognitive chiral separation of tartaric acid enantiomers from ethanol solution. Kinetic properties were successfully investigated by pseudo-first-order model and pseudo-second-order model. Equilibrium data were described by the Langmuir and Freundlich isotherm models. The thermodynamics parameters (positive values of ΔH° and ΔS°, negative values of ΔG°) indicated that binding system for L-Trp-CD was endothermic, entropy gained and spontaneous. Selective adsorption result of l-tartaric acid (L-TA)/d-tartaric acid (D-TA) by L-Trp-CD indicated that L-Trp-CD has significantly higher adsorption capacity for L-TA compared with D-TA, and the selectivity coefficient is 3.36.

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