Adsorption of 4-nonylphenol ethoxylates onto insoluble chitosan beads bearing cyclodextrin moieties

In order to develop a treatment method for industrial wastewater, the adsorption of 4-nonylphenol ethoxylates (NPEs), non-ionic surfactants used in the industry, onto chitosan beads having cyclodextrin (CDC beads) was investigated. Three kinds of CDC beads containing different cyclodextrin (CD) moieties were prepared from poly-carboxymethylated α-, β- and γ-CDs. Among α-, β- and γ-CD cavities, β-CD was the most suitable for the adsorption of the phenol derivatives. The amount of adsorption was greater for the NPEs having shorter ethoxylates. Most of the NPE adsorbed on the β-CDC beads were successfully released by the treatment of the CDC beads with various aqueous alcohol solutions. After 20 cycles of the adsorption–desorption were completed, no significant decline in the adsorption amount was observed. Continuous adsorption tests were carried out using the CDC beads filled in a glass column. At the appropriate flow rate, the NPE can be adsorbed with a reasonable saturation amount.