Adsorption of cephalexin from aqueous solution using natural zeolite and zeolite coated with manganese oxide nanoparticles

In the present study the adsorption of Cephalexin (CEX) from aqueous solution using natural zeolite (NZ) and zeolite coated with manganese oxide nanoparticles (CZ) were investigated as a function of pH, shaking time, initial CEX concentrations, adsorbent dose, and competitive ions. Scanning electron microscope (SEM) images, X-ray diffraction (XRD) patterns, X-ray fluorescence (XRF) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were used to characterize the adsorbents. The maximum CEX removal efficiency was 28% and 89% for NZ and CZ, respectively, at pH 7. The experimental isotherm data were analyzed by Freundlich, Langmuir, Redlich-Peterson, and Sips models. The results showed that Sips isotherm was the best model and the maximum adsorption capacity went from 16.1 mg/g for the NZ to 24.5 mg/g for the CZ, for 2 g/L adsorbent dose. Comparison of these results with those obtained from previous literature suggested that CZ can be potentially used for CEX removal from aqueous solution. The kinetics of CEX adsorption with different initial concentrations were better fit by the pseudo-second-order model, with higher coefficient of determinations and more closely predicted uptake. Finally, the results showed that the intraparticle diffusion was the dominating mechanism.