Simple synthesis of a swellable porous β-cyclodextrin-based polymer in the aqueous phase for the rapid removal of organic micro-pollutants from water

Abstract

Regenerable adsorbents with rapid adsorption are highly desirable for water treatment. Cyclodextrin-based adsorbents have been attracting increasing attention because of their high affinity for a variety of organic compounds. All previously reported porous cyclodextrin-based polymers were synthesized in the organic phase, which required a long reaction time and high cost and resulted in an adverse impact on the environment. In this study, a novel macroporous and ultra-microporous beta-cyclodextrin-based polymer (T-E-CDP) was prepared in the aqueous phase for the first time by simultaneously crosslinking beta-cyclodextrin with both flexible and rigid crosslinkers. Owing to the porous structure and easy access of adsorption sites, T-E-CDP exhibited ultra-rapid adsorption of organic micro-pollutants, such as bisphenol A (BPA), 3-phenylphenol (3-PH), and ethinyl estradiol (EE2), with an adsorption rate constant 45 and 581 times those of the commercial adsorbents, activated carbon and XAD-4 resin, respectively. The polymer adsorbent could be easily regenerated by methanol at room temperature and reused many times without a significant decrease in the adsorption performance. More importantly, T-E-CDP could effectively remove many organic pollutants from water at environmentally relevant concentrations and without being affected by the pH level, ionic strength, and humic acid concentration, indicating that it is very suitable for application in practical water treatment. It is particularly important that T-E-CDP can be easily degraded without causing secondary pollution after use, and the synthesis process of T-E-CDP is green, low-cost, and easy to industrialize.