Efficient adsorption of bisphenol A from water by a hierarchically porous hyper-crosslinked polymer containing β-cyclodextrin polyurethane

Bisphenol A (BPA) is a common industrial products ingredient, whose widespread utilization leads to a non-negligible problem of water pollution. For efficient adsorption of BPA, hyper-crosslinked β-cyclodextrin polyurethane (CDPU-HCP) was synthesized via crosslinking β-cyclodextrin (β-CD) with 4,4′-diphenylmethane diisocyanate followed by further external crosslinking reaction. CDPU-HCP showed high surface area (1133.12 m2∙g−1) and has hierarchically pores, such as β-CD nanocavities, micropore and mesopores. Adsorption data fitted better with Freundlich adsorption isotherm model and the pseudo second order kinetic model. The fitted maximum adsorption capacity toward BPA was shown to be 371.8 mg∙g−1. The stable adsorption performance during successive six recycling experiments indicated the excellent recyclability of CDPU-HCP. Furthermore, the density functional theory (DFT) calculations showed hydrophobic interaction of β-CD cavity and π-π interactions between aromatic moieties and BPA synergistically promoted the adsorption process. Therefore, CDPU-HCP was suggested to be a promising adsorbent in the treatment of BPA.