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.

Studies on adsorption of dyes on beta-cyclodextrin polymer

Beta-cyclodextrin (beta-CD) polymers are used for the removal of various dyes from aqueous solutions. Three insoluble polymers with different degrees of beta-CD were used. Results of adsorption experiments showed that these polymers exhibited high sorption capacities toward dyes. The mechanism of adsorption was both physical adsorption and hydrogen bonding due to the polymer and the formation of an inclusion complex due to the beta-CD molecules through host-guest interactions.

Evaluation of beta-cyclodextrin bonded silica as a selective sorbent for the solid-phase extraction of 4-nitrophenol and 2,4-dinitrophenol

A beta-cyclodextrin bonded silica was synthesized by using a convenient method, and was evaluated as a selective sorbent for the solid-phase extraction of 4-nitrophenol and 2,4-dinitrophenol. When double-distilled water was used as the sample matrix, the sorbent showed a strong capacity to adsorb 4-nitrophenol and 2,4-dinitrophenol; the recoveries were found to be 96% and 99%, respectively, with a 1 L water sample. The selectivity of the sorbent was investigated by using a washing step with methanol. Most of the phenols were washed out with 5 mL of methanol, while 4-nitrophenol and 2,4-dinitrophenol still gave recoveries of 94% and 90%. The solution for efficiently eluting the analytes was optimized and the effect of the inorganic salt on the extraction was examined. In order to investigate the potentiality of the sorbent in dealing with real water samples, water from Donghu lake (Wuhan, China) spiked with nine phenolic compounds at microgram per liter levels were preconcentrated on this cartridge.