Surface molecular imprinting on carbon microspheres for fast and selective adsorption of perfluorooctane sulfonate

Abstract

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant with high biological and chemical stability. It is important to develop fast and selective adsorption method for PFOS wastewater treatment. In this study, novel molecularly imprinted polymer (MIP) for PFOS adsorption was prepared. To obtain rapid adsorption kinetics, the MIP has been designed as the surface polymer using the carbon microsphere as carrier (MIP-CMSs). To ensure high adsorption selectivity to the template, two monomers with different functional structures, namely methacryloyloxyethyl trimethyl ammonium chloride (DMC) and 2-(trifluoromethyl)acrylic acid (TFMA), were employed as bi-functional monomers. The structure and morphology of MIP-CMSs were characterized using field emission scanning electron microscopy with the energy dispersive spectrometer, transmission electron microscopy, and Fourier transformation infrared spectroscopy. Based on the adsorption experiments, it was concluded that MIP-CMSs had specific binding property for PFOS on acidic condition. The adsorption equilibrium time was 1h, while the adsorption capacity was 75.99 mg g^-1 at pH 3. Coexistence with contaminants with different structures had little influence on the selectivity for PFOS. The spent MIP-CMSs could be regenerated by the methanol and acetic acid mixed solution. The electrostatic interaction and molecular size played important roles in recognizing the target compound in the adsorption process.

Keywords: Bi-functional monomer; Carbon microspheres (CMSs); Perfluorooctane sulfonate (PFOS); Selective adsorption; Surface molecular imprinting.