Kinetic, isothermal, and thermodynamic models to evaluate acid blue 161 dye removal using industrial chitosan powder

Abstract

Textile dyes are often discarded into the environment. Most of them are toxic and their release leads to severe impacts. This study evaluated the potential of industrial chitosan powder as an adsorbent material capable of removing such toxic compounds from aqueous solutions. Our experimental approach evaluated the removal of Acid Blue 161 azo textile dye. We further investigated the kinetics, isotherms, and thermodynamics of the chitosan-mediated adsorption. The chitosan powder had a high rate of dye adsorption, thus requiring only 111.45 mg of adsorbent to remove 100 µg mL–1 of dye. It also reached equilibrium very rapidly (before 180 min), at a 20-min settling rate. We demonstrated that acidic pH increased the interaction between adsorbate/adsorbent, as the maximum adsorption capacity (10.301 µg mL–1) occurred at pH 2.50. Kinetic studies indicated intraparticle diffusion of dye molecules in chitosan particles. The thermodynamic studies have shown that temperature influences the adsorption, in which higher temperatures improved adsorption. The thermodynamic analysis also showed that adsorption is an endothermic process. Fourier transform infrared spectroscopy confirmed that acidic pH triggered chemisorption and improved adsorbate/adsorbent interaction.