Functional Groups and Interactions Controlling the Adsorption of Bisphenol a onto Different Polymers

Abstract

The behaviour of different polymers in the adsorption and removal of bisphenol A (BPA) from aqueous solutions was examined in order to identify the mechanism controlling the process. Three polymers with different functional groups were prepared and employed in our laboratory; they were characterized both texturally and chemically in terms of their surface areas, pore-size distributions, total exchange capacities and other parameters. The adsorption isotherms of bisphenol A were obtained and accurately modelled by the three-parameter Langmuir–Freundlich (LF) isotherm, the binding parameters calculated directly by the LF fitting coefficients indicating that increasing temperature was helpful in causing the adsorption process to move from positive cooperativity to negative cooperativity. The kinetic data were found to be well represented by the pseudo-second-order kinetic model, indicating that the functional groups of the polymers had a significant influence on the adsorption mechanism of BPA. The adsorption of BPA basically depended on the chemical nature of the polymers and the pH value of the solution. The adsorption process was favoured by the molecular form of bisphenol A, since this controlled the surface complexes produced between the polymer surface and the bisphenol A molecules, with the resulting increase in adsorbent–adsorbate interactions being positively influenced by the temperature.