Kinetics and mass transfer aspects about the adsorption of tartrazine by a porous chitosan sponge

Abstract

Kinetic and mass transfer aspects about the adsorption of tartrazine on a porous chitosan sponge (PCS) were elucidated. PCS was prepared and characterized. The kinetic curves were obtained in batch mode at different stirring rates and initial dye concentrations. The kinetic data were evaluated by the pseudo-first order, pseudo-second order (PSO), Elovich and Avrami models. The mass transfer aspects were evaluated by the external mass transfer coefficient (kf), intraparticle diffusion coefficient (Dint) and modified Biot number (Bi). The results revealed that PCS presented specific surface area around of 1150 m2 g−1 and porosity of 92 %. The adsorption kinetics was favored at higher values of stirring rate and initial dye concentration. PSO and Elovich models were suitable to represent the kinetic data. The kf values ranged from 7.38 × 10−3 to 5.25 × 10−1 m s−1 and the Dint values ranged from 8.93 × 10−10 to 4.72 × 10−9 m2 s−1. The Bi values at lowest stirring rates and initial dye concentrations showed that the external mass transfer should be considered. Otherwise, a complete dominance of intraparticle diffusion occurred at highest values of stirring rate and initial dye concentration.