Equilibrium, Kinetic and Thermodynamic Studies for the Adsorption of Gemfibrozil onto Graphitized Carbon Black (GCB)

Adsorption of gemfibrozil (GF) from aqueous solution by highly/lowly graphitized carbon black (GCB-H/GCB-L) was investigated by batch and fixed-bed experiments. Results showed that the adsorption of GF onto GCB greatly depended on solution pH and graphitization of carbon. The pseudo-second-order kinetic model was found to be more appropriate in describing the adsorption processes of two GCBs. The adsorption equilibriums were well fitted with the Langmuir isotherm model, and GCB-H exhibited a higher adsorption capacity of 47.68 mg g(-1) at 298 K, compared with GCB-L of 4.33 mg g(-1). GCB-H achieved 69.76% GF removals in simulated water after 6 h, indicating its potential practicability. The GCBs were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR), and the results indicated that the pi-pi interaction was strongly involved in the adsorption. Thermodynamic studies further suggested that the adsorption of GF on GCB-H was exothermic, which could happen spontaneously at any temperature mainly through pi-pi interaction for physical adsorption on the surface of the plane.