Synthesis of a terpolymer based on chitosan and lignin as an effective flocculant for dye removal

Flocculant based on natural polymer has attracted more attention duo to its rich source, low cost and eco-friendliness. In this paper, we adopted a synthetic monomer of acrylamide to graft chitosan and lignin together by microwave assisted method. Flocculation studies showed that chitosan-acrylamide-lignin (CAML, 2 g:2 g: 2 g) terpolymer exhibited maximum percentage removal of 99.3% and 67.0% for reactive orange C-3R and methyl orange, respectively. The soluble CAML flocculant had a wide flocculation window and pH effective range, although the flocculation efficiencies were enhanced slightly under acid condition. The flocculation mechanism was combined charge neutralization and bridging effects. The cost-effective, eco-friendly and high efficient terpolymer has great potential to serve as an excellent flocculant for dye removal.