Preparation of Molecularly Imprinted Carbon Microspheres by One-Pot Hydrothermal Method and Their Adsorption Properties to Perfluorooctane Sulfonate
Abstract Molecularly imprinted carbon microspheres (MIC) were synthesized by one-pot hydrothermal method with perfluorooctane sulfonate (PFOS) as template, Camellia oleifera seed shell as carbon precursor and phloroglucinol as additive. The as-prepared PFOS-MIC was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area and pore size distribution analyzer (BET), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetry/differential thermal analyzer (TG/DTA). The results of SEM, HRTEM and FT-IR showed that the PFOS-MIC had a particle size of about 1.5 μm, the activated binding sites were formed by a large number of interconnected hydrogen bonds. The adsorption properties of PFOS on PFOS-MIC and the corresponding non-imprinted carbon microspheres (NIC) such as adsorption kinetics, pH effect and adsorption isotherms were investigated. The results showed that the adsorption kinetics of PFOS on both NIC and PFOS-MIC fitted well with the secondary-kinetic model (R2 > 0.994). Under the experimental conditions of 20 °C and pH = 3, the adsorption equilibrium time was 1.5 and 3.0 h, respectively. The lower pH was in favor of the adsorption. The adsorption isotherms data fitted better to the Langmuir model (R2 > 0.993) than that of Freundlich model, and the maximum adsorption capacity at 20 °C was 2.93 and 5.38 mg g−1 for NIC and PFOS-MIC, respectively. Adsorption selectivity results indicated that the PFOS-MIC had good adsorption selectivity for PFOS, even in coexistence with the structural similar surfactants.