The efficient removal of anionic and cationic dyes from aqueous media using hydroxyethyl starch-based hydrogels

In this study, hydroxyethyl starch (HES)-based hydrogels, hydroxyethyl starch/p(sodium acrylate) (HES/p(NaAAc)), hydroxyethyl starch/p(3-(acrylamidopropyl) trimethyl ammonium chloride) (HES/p(APTMACl)) and hydroxyethyl starch/p(acrylamide) (HES/p(AAm)) were synthesized with redox polymerization. The structural, morphological, and water absorption characterization of the synthesized hydrogels was investigated. HES-based hydrogels, containing anionic, cationic and neutral functional groups, were used for adsorption of methyl violet (MV) as a model cationic dye and methyl orange (MO) as a model anionic dye from aqueous media. HES/p(APTMACl) and HES/p(NaAAc) hydrogels had maximum adsorption values for MO and MV dyes of 238.1 mg/g and 185.2 mg/g. The isotherm and kinetic parameters for both dye adsorptions were determined. The adsorption isotherm and kinetic data were compatible with the Langmuir isotherm and pseudo-first-order kinetic models.