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 beta-CDs was the largest of the natural CDs. The initial apparent association constant for MTBE-CD complex follows the order: gamma = beta > methyl-beta > hydroxypropyl beta > alpha. The difference in these constants is related to the size of MTBE and CDs. The size of beta- and gamma-CD is large enough to encapsulate MTBE molecule into the cavity, which that of alpha-CD is too small to encapsulate MTBE. (C) 2003 Elsevier B.V. All rights reserved.