Removal of Pb (II) by crosslinked amphoteric starch containing the carboxymethyl group

The adsorption process of Pb (II) ions from aqueous solution by crosslinked amphoteric starch with quaternary ammonium and carboxymethyl groups was investigated. The adsorption capacity is found to be dependent on the pH of the solution, the dose of the crosslinked amphoteric starch, and the initial concentration of Pb (II) ion. Moreover, the adsorption capacity increases with the increasing degree of substitution (DS) of carboxymethyl groups. The Langmuir adsorption isotherm gave a satisfactory fit of the equilibrium data. The adsorption process is endothermic, and thermodynamic parameters were calculated at different DS.