Green synthesis of nano-zero-valent iron from Nettle and Thyme leaf extracts and their application for the removal of cephalexin antibiotic from aqueous solutions

In this study, the removal of cephalexin (CEX) antibiotic from aqueous solution was examined using a novel green adsorbent without employing any toxic chemicals or capping agents. Nettle and Thyme extracts were used to synthesize novel nano-zero-valent iron (NNZVI and TNZVI) for the adsorption of CEX. The nature and morphology of synthesized adsorbent were characterized by Transmission electron microscopy, scanning electron microscope, X-ray diffraction and Fourier transform infrared spectroscopy spectroscopy. Batch experiments were performed to study the influence of various experimental parameters such as contact time, initial concentration of the CEX, solution pH and adsorbent dosage. The adsorption isotherms of CEX by NNZVI and TNZVI were found to fit well with Freundlich and Langmuir models, respectively. The maximum adsorption capacity of CEX onto NNZVI and TNZVI were observed as 1667 and 1428mg/g, respectively, based on the Langmuir model. The adsorption trend followed the pseudo-first-order kinetics model and equilibrium could be established in about two hours for both adsorbents. The developed nanoparticles in this study have considerable potential for the removal of CEX and could be considered as a promising adsorbent for the removal of other antibiotics also from aqueous solutions.