Competitive adsorption of methylene blue and Pb (II) ions on the nano-magnetic activated carbon and alumina

The adsorption of methylene blue (MB) in single and binary solutions were investigated on new promising functionalized magnetic wood based activated carbon (MFMWAC), peach stone activated carbon (MFMPAC) and alumina (MFMA) derived by a facile preparation method. Characterization of the magnetic nano-adsorbents was achieved by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), Vibrating sample magnetometer (VSM) and zeta potential tests. Findings revealed that the core-shell magnetite nanocomposites were formed with size of less than 50 nm. The kinetic and isotherm models were also analyzed for the adsorption of MB. Equilibrium adsorption was evaluated employing Langmuir and Freundlich equations, in which Freundlich model was in good agreement with the experimental results. Maximum adsorption capacities of MFMWAC, MFMPAC and MFMA were measured as 434.13, 437.78 and 196.08 mg/g for MB, respectively. The pseudo second order kinetic with higher correlation coefficient indicated a better fit with MB adsorption. Competitive adsorption of MB disclosed that the adsorption capacities of the carbonaceous adsorbents for MB reduced considerably by adding the Pb (II) ions to the aqueous solutions. However, the remarkable capacity of MB was calculated to be 175.39 and 182.45 mg/g by using the extended Langmuir for MFMWAC and MFMPAC, respectively in the binary solution. Reusability of the magnetic adsorbent was also investigated in the competitive adsorption for six cycles which showed that the prepared adsorbent can be used for the real applications.