Selective adsorption of anionic dyes from aqueous solution by a novel β-cyclodextrin-based polymer

Abstract

Abstract β-cyclodextrin (β-CD) was firstly crosslinked by tetrafluoroterephthalonitrile and then modified by ethanolamine (EA) to form a novel β-cyclodextrin-based polymer (EA-CDP). The microstructure and the properties of the EA-CDP were characterized by SEM, MIP, 13C NMR, FTIR, water contact angle measurement, zeta potential measurement, and TGA. The resultant EA-CDP could effectively select the anionicmethyl orange (MO) dye from the mixed-dye aqueous solution of MO and cationic methylene blue (MB) dye. The absorption capacity of the EA-CDP for anionic dyes including MO and Congo red (CR) increased with the decreasing pH value. The pseudo-second-order kinetic was more ideal to describe the absorption behavior of EA-CDP for MO and CR than the pseudo-first-order model. According to the fitting result of the Langmuir equation, the maximum absorption capacity of the EA-CDP for MO and CR reached as high as 602 mg/g and 1085 mg/g, respectively. Such a high absorption capacity could be ascribed to the triple absorption effects of the EA-CDP for anionic dyes including porous network capture, inclusion complextion, and electrostatic attraction.