Adsorption behavior and mechanism of aqueous organic contaminants on β-cyclodextrin polymer

The β-cyclodextrin polymer, synthesized using tetrafluoroterephthalonitrile (TFPN-β-CD), was employed for the adsorption of ten organic contaminants in water. Among them, methylene blue (MB), bisphenol A (BPA), tetracycline, and kaempferol exhibited superior adsorption efficiency and were selected for detailed investigation. Toth isotherm model appropriately described the adsorption process of TFPN-β-CD with MB, BPA, tetracycline and kaempferol compared with Langmuir and Freundlich isotherm models. The PSO model showed ideal fitting for the adsorption process of TFPN-β-CD to four organic contaminants in adsorption kinetics fitting. Weakly acidic aqueous solutions enhanced adsorption capacity, whereas inorganic salts caused erosion during the adsorption process. Dynamic factors such as loading capacity, pH, flow rate, renewability, and reusability were investigated using MB as an example. Higher loading capacity and flow rate favored improved adsorption efficiency; moreover, TFPN-β-CD could be easily regenerated and reused. Importantly, the respective mechanisms underlying TFPN-β-CD's adsorption were elucidated: electrostatic interactions exerted a stronger force than hydrophilic & hydrophobic interactions in the case of MB; however, hydrophilic & hydrophobic forces played significant roles in BPA, tetracycline, and kaempferol adsorptions.