Preparation of lignosulfonate-acrylamide-chitosan ternary graft copolymer and its flocculation performance.

As flocculant plays an important role in wastewater treatment, searching for high efficient and cost-effective flocculants has always become the challenge in chemical industry. In the current work, lignosulfonate-acrylamide-chitosan ternary copolymer was designed and prepared as a new kind of flocculant. The elemental analysis and structure characterization of FTIR and XRD showed that acrylamide successfully grafted onto the two natural polymers and amorphous macromolecules were formed. The natural polymers-based flocculant was water soluble and pH independent. As it had multiple functional groups from the raw materials, the amphoteric flocculant showed high color removal efficiency to anionic (acid blue 113, >95%), neutral (reactive black 5, >95%) and cationic dyes (methyl orange, >50%) in a wide range of flocculant dosage and pH windows. The ternary flocculant, based on lignosulfonate, chitosan, and acrylamide, might be a promising material in practical applications from the perspective of cost, source and performance.