Removal of Methotrexate from Aqueous Solutions Using AC@Fe3O4@ZnO Nanocomposite: Equilibrium and Kinetic Studies

Since pharmaceutical residues are important pollutants that lead to producing serious hazards to humans, and other living organisms, their removal from the effluents is essential for environmental protection. This study was conducted to the evaluation of the removal efficacy of methotrexate from aqueous solutions using AC@Fe3O4@ZnO nanocomposite. In so doing, AC@Fe3O4@ZnO nanocomposite was synthesized by hydrothermal method and used as a novel adsorbent for the removal of methotrexate from an aqueous solution. AC@Fe3O4@ZnO nanocomposite characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), pHpzc, Fourier transform infrared spectroscopy (FTIR), Brunauer, Emmett, and Teller (BET) and vibrating sample magnetometry (VSM) analysis methods. The influence of pH, amount of adsorbent, temperature, and contact time on the removal efficacy were studied. Based on the results, the removal efficiency increased until 0.02 g adsorbent and 60 min contact time. The optimum pH for methotrexate removal was 7.0. In addition, under these conditions, the adsorption process followed the Langmuir adsorption isotherm with a correlation coefficient of 0.994 and a pseudo-second-order kinetic model with a correlation coefficient of 0.999. The maximum adsorption capacity of the synthesized adsorbent was 400 mg/g. In conclusion, the AC@Fe3O4@ZnO nanocomposite could be considered as an efficient adsorbent for the removal of methotrexate from pharmaceutical wastewater.