Adsorption of cationic dye using novel O-amine functionalized chitosan schiff base derivatives: Isotherm and kinetic studies

Abstract

New Schiff bases of O-amine functionalized chitosan derivatives were obtained from the coupling of O-amine functionalized chitosan with 4-methoxy benzaldehyde (Schiff base I), 4-chloro benzaldehyde (Schiff base II), and diethyl amino acetone (Schiff base III). The structure of the prepared innovative Schiff bases was characterized using Fourier transform infrared, thermal gravimetric analysis, differential scanning calorimetry, and scanning electron microscope. A batch system was applied to study the adsorption of methylene blue (as a model of cationic dye) from aqueous solutions using these new Schiff bases. The adsorption parameters were studied and recorded for prepared derivatives as: pH 7, 250 rpm, and time 40, 120, and 180 min for Schiff bases (I), (II), and (III), respectively. And the maximum adsorption capacity was recorded as 35.6, 25.79, and 30.51 mg/g for the same sample order. The equilibrium adsorption data of reactive dye on O-amine functionalized chitosan derivatives were analyzed by Langmuir and Freundlich models. The Freundlich model represents the experimental data better that Langmuir one (with R2 (I) = 0.9807, R2 (II) = 0.983, and R2 (III) = 0.9994). The kinetic adsorption data were analyzed using four different kinetic models: pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Avrami models. Obtained results were more fit to pseudo-second-order model (with R2 (I) = 0.9970, R2 (II) = 0.9968, and R2 (III) = 0.9995).