Fabrication of Lignin-based Magnetic Adsorbent via Thiol-ene Click Reaction for the Effective Removal of Pb(II)

Abstract The effective and selective removal of heavy metal ions from sewage is a major challenge, and of great significance to the treatment and recovery of metal waste. Herein, a novel magnetic lignin-based adsorbent L@MNP was synthesized by thiol-ene click reaction under UV light irradiation. Multiple characterization techniques containing FT-IR, XRD, elemental analysis, VSM, SEM and TEM confirmed the formed nano-morphology and structure of L@MNP. Effects of pH, contact time, initial metal concentration and temperature on the batch adsorption of Pb(II) by L@MNP were investigated. Due to the existence of sulfur and oxygen containing sites, the maximum adsorption capacity of L@MNP for Pb(II) could reach 97.38 mg/g, while the adsorption equilibrium was achieved within 30 min. Adsorption kinetics and isotherms were well described by the pseudo-second-order model and Langmuir model, respectively, suggesting a chemical and monolayer adsorption process. In addition, L@MNP showed a high adsorption selectivity (kPb = 0.903) toward Pb(II) in the presence of other co-existing metal ions. Experimental results also revealed that L@MNP displayed structural stability, easy recovery under external magnetic field, and acceptable recyclability after the fifth cycle. Considering its facile preparation, low cost and high adsorption efficiency, the developed L@MNP adsorbent demonstrated great potential in removing heavy metal ions from wastewater.