Preparation of Lignin-Based Hydrogel and Its Adsorption on Cu 2+ Ions and Co 2+ Ions in Wastewaters

In the present study, we prepared a newly adsorbent, Chitosan (CTS) and sodium lignosulphonate (SLS) were added as monomers for the copolymerization of acrylic acid (AA), then ammonium persulfate (APS) bisacrylamide (NMBA) as a cross-linking agent, under the premise of ultrasound mixed uniformly prepared lignin-based hydrogel. The hydrogel samples were characterized by SEM, FT-IR and TG analysis. Finally, the samples were applied to the adsorption of heavy metal ions Cu2+ and Co2+. The influences of external environmental factors such as pH value, adsorption time, adsorbent dosage and initial concentration of heavy metal ions on the adsorption process were discussed. It was found that the optimum pH value for the adsorption of two heavy metal ions was close to 6, and the adsorption kinetics was found to fit the pseudo-second-order model and the isotherm model was fitted to the Freundlich model. Among them, the adsorption capacity of Co2+ is 385 mg g−1 and Cu2+ is 290 mg g−1.