Preparation of insoluble chitosan beads functionalized by carboxymethylated β-cyclodextrin

Insoluble spherical chitosan beads bearing P-cyclodextrin moieties (CDC beads) were prepared by a condensation between multiply carboxymethylated P-cyclodextrin and chitosan beads without any further crosslinking. The shape of the original chitosan beads was retained when the reaction was carried out at pH 9 or pH 10 but the reaction at pH 7 and pH 8 gave powder and highly swelled product, respectively. The CDC beads adsorbed more than 85% of bisphenol A from 10(-5) mol/L aqueous solution while the chitosan adsorbed only 2 %. The CDC beads also adsorbed 4-nonylphenol and 4-nonylphenol ethoxylates from aqueous solution. We concluded that the CD moieties worked both as crosslinker and as adsorption sites. We also confirmed that almost all of the bisphenol A and 4-nonylphenol adsorbed was released from the CDC beads by a treatment with 50% aqueous ethanol solution.