Abstract: | Crosslinked amphoteric starches (CASs) with quaternary ammonium cationic and carboxymethyl anionic groups were prepared by a hemidry reaction. Their adsorption behavior for Cr(VI) was investigated, and was found to follow the Langmuir isotherm. The adsorption process was found to be dependent on initial pH, concentration of Cr(VI), dose of CAS, and temperature. The adsorption capacity decreased with increasing degree of substitution of anionic groups. The thermodynamic study indicated that the adsorption process was exothermic, and the enthalpy changes (ΔHθ), the entropy changes (ΔSθ), and free energy changes (ΔGθ) for CASs were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 263–267, 2003 |