A phenyl-rich β-cyclodextrin porous crosslinked polymer for efficient removal of aromatic pollutants: Insight into adsorption performance and mechanism

Herein, a phenyl-rich beta-cyclodextrin porous crosslinked polymer (PCD-PCP) with high phenyl content and consistent pore structure was used to remove the aromatic pollutants from water. The PCD-PCP was obtained through the efficient Friedel-Crafts alkylation of benzylated beta-cyclodextrin with the crosslinker 4,4'-bis(chloromethyl)-1,1'-biphenyl. We have demonstrated that by controlling the crosslinking degree, the nanostructure, porous features and phenyl contents of the resulting materials can be tuned, in turn allowing the control of the adsorption capacities. Impressively, PCD-PCP(H) with high crosslinking density exhibited a notable sorption ability and good recyclability for removal of organics from contaminated water. Using 2,4,6-trichlorophenyl and bisphenol A as model adsorbates, the adsorption processes both fitted well the pseudo-second-order model and the Freundlich model, and thermodynamic studies certified that the adsorption was a spontaneous and exothermic process. PCD-PCP(H) was able to maintain high adsorption capacity in wide pH and ionic strength ranges as well as in recycling process. Furthermore, the comprehensive analysis of experimental and theoretical calculations results suggested that the pi-pi interactions and host-guest interactions may jointly promote the uptake process, providing new insights into the development of advanced beta-cyclodextrin based adsorbents for aromatic molecule adsorption.