Flocculation of heavy metal by functionalized starch-based bioflocculants: Characterization and process evaluation

Abstract Two bioflocculants of starch-graft-P[acrylamide-acrylic acid] (SAA) and starch-graft-P[acrylamide-2-acacrylamido-2-methyl-1-propanesulfonic acid] (SAS) are designed for the flocculation–chelation of heavy metals. The successful polymer synthesis is confirmed through physicochemical characterization. SAA and SAS are used to remove Cu(II), Zn(II), and Ni(II) from simulated wastewater and Ni(II) from actual electroplating wastewater. The removal efficiencies for Cu(II), Zn(II), and Ni(II) in the simulated wastewater by SAA and SAS are more than 80.00%, whereas those for Ni(II) are more than 90.0% in the Ni-containing electroplating wastewater at the optimal condition. Flocculation experiments reveal that the sulfonate structure of SAS is highly conducive to improve flocculation efficiency. SAA and SAS have high selectivities for Cu(II) in the simulated water sample with mixed heavy metal. Finally, the 3E (i.e., environmental impact, economic benefit, and energy consumption) triangular evaluation model is established to evaluate the flocculation experiments for the removal of heavy metal ions using SAA and SAS.