Immobilization behavior of methyl tert-butyl ether by cyclodextrins

The immobilization behavior of methyl tert-butyl ether (MTBE) by various cyclodextrins (CDs) was studied. Although it has a low hydrophobic character and high polarity compared to other organics, MTBE was effectively immobilized by CDs. The immobilization isotherm was a type of Freundlich isotherm. The immobilization capacity of β-CDs was the largest of the natural CDs. The initial apparent association constant for MTBE-CD complex follows the order: γ = β > methyl-β > hydroxypropyl β > α. The difference in these constants is related to the size of MTBE and CDs. The size of β- and γ-CD is large enough to encapsulate MTBE molecule into the cavity, which that of α-CD is too small to encapsulate MTBE.