Ethanolamine- and amine-functionalized porous cyclodextrin polymers for efficient removal of anionic dyes from water

Abstract Functionalized modification of materials can be used to tailor their interaction ability and adsorption performance toward target pollutants. Tetrafluoroterephthalonitrile-linked porous β-cyclodextrin polymer (P-CDP) has excellent adsorption capacity toward cationic and neutral pollutants, but a weak ability to adsorb anionic pollutants. Herein, two modified cyclodextrin polymers were prepared. The nitrile groups in P-CDP were transformed into ethanolamine and amine via the reaction with ethanolamine and borane complexes, and the obtained products were used for dye removal. The functional modification changed the adsorption selectivity from toward cation to toward anion, and significantly improved the adsorption capacity toward anion. Using methyl orange as the model anionic adsorbate, the maximum adsorption capacity of ethanolamine-functionalized one reached 625 mg g−1, which is far higher than those of most reported adsorbents. The adsorption isotherms better fitted to Langmuir model and kinetic study showed a pseudo second-order adsorption. The as-prepared modified-polymers with superior adsorption ability and selectivity toward anion are expected to be applied to removing anionic pollutants from waste water.