Two lignin-based adsorbent hydrogels for the removal of heavy metal ions, namely bentonite/sodium lignosulfonate graft acrylamide (BLPAM) and bentonite/sodium lignosulfonate graft acrylamide and maleic anhydride (BL-PAMA), were prepared by solution graft-copolymerization using sodium lignosulfonate (LS-Na), acrylamide (AM) and maleic anhydride (MAH) as raw materials, bentonite as inorganic filler, potassium peroxydisulfate (KPS) as initiator, N, N-methylene-bis-acrylamide (NMBA) as crosslinker. The effect of different post-treatme...