Study of congo red dye removal from its aqueous solution using sulfated acrylamide and N, N- dimethyl acrylamide grafted amylopectin

Sulfation of amylopectin, amylopectin-g-polyacrylamide and amylopectin-g-N,N-dimethyl acrylamide was carried out by using chlorosulfonic acid as the sulphating agents. The sulfated polymers were characterized by measuring degree of sulfation, FTIR and XRD studies. The three sulfated and the three unsulfated polymers were used for congo red dye adsorption from water medium. Adsorption dynamics, adsorption kinetics and adsorption isotherms of all the sulfated products were evaluated. Competitive dye removal characteristics of all the sulfated products were carried out in a mixture of congo red/methylene blue and congo red/malachite green solutions. The adsorption mechanism was studied theoretically by Density Function Theory (DFT), using Gaussian 09 programme. Sulfated products showed better dye adsorption properties than the unsulfated products where as among the sulfated products, sulfated amylopectin-g-polyacrylamide performed best. Theoretical and experimental studies showed that hydrogen bonding is mainly responsible for the dye adsorption.