Removal of food dyes from aqueous solution by chitosan-vermiculite beads

Abstract

In this study, Chitosan (Ch)-Vermiculite (V) composite beads material which is a low-cost and naturally effective adsorbent were used for efficient removal of Sunset Yellow FCF (Sy) and Brilliant Blue FCF (Bb) food dyes from aqueous solution. Ch-V composite beads were characterized by using FTIR, SEM, XRD and PZC analysis. The adsorbent properties of Ch-V composite beads for Sy and Bb dyes were evaluated in terms of pH, concentration, kinetic (time) and thermodynamic (temperature) of adsorption. The experimental data presented were obtained from Langmuir, Freundlich and Dubinin-Radushkevich (DR) isotherm models. The maximum adsorption capacity for the Langmuir equation was found to be 0.387 mol kg^-1 for Sy and 0.229 mol kg^-1 for Bb, respectively. The results showed that the experimental data were better fit the Langmiur model for Sy and the Freundlich model for Bb. Adsorption energies obtained from DR model for Sy and Bb showed that adsorption processes were chemically. The pseudo-second order and intra-particle diffusion models of adsorption kinetics are in accordance with Sy and Bb. As a result of thermodynamic evaluation of Sy and Bb adsorption, it was found that adsorption processes were endothermic, entropy increased and reaction was spontaneous.

Keywords: Adsorption; Brilliant blue; Chitosan; Food dyes; Sunset yellow; Vermiculite.