One-pot method to prepare lignin-based magnetic biosorbents for bioadsorption of heavy metal ions

Valorization of lignin is imperative since lignin is still an underutilized biomaterial. Herein, a facile fabrication method for lignin-based magnetic biosorbent (LMB) is proposed via assembling magnetic inorganic particles (Fe3O4) on lignin in-situ for eliminating heavy metal ions (HMIs) from wastewater without the utilization of organic solvents. Chemical and structural characterizations, which were determined by different analytical tools, including Fourier transform infrared (FTIR), Scanning electron microscope (SEM), X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) confirmed that LMB was successfully formed via the feasible and green process. Then, LMB was found to exhibit highly effective removal performance for HMIs. The adsorption capacity of the LMB reached 152.58 mg/g for Pb2+ and 46.81 mg/g for Cu2+, with equilibrium attained within 30 min. Adsorption kinetics and isothermal adsorption of lead and copper ions by LMB were also examined. This study delivers a new perspective on lignin valorization for lignocellulose biorefineries and establishes a path for synthesizing a cost-efficient and green adsorbent for removing HMIs from wastewater.