Adsorption kinetics, equilibrium, and thermodynamic studies to understand adsorption behavior of Evans blue dye by durian husk

Membrane isolation, ion exchange, precipitation, transformation, and biosorption are all viable methods for pollutant removal. Adsorption is a common commercial method to concentrate precious molecules or eliminate contaminants, and it is a cost-effective method of treating industrial wastewater. A novel method for increasing their removal effectiveness has been developed for this purpose, using a low-cost biosorbent made from durian husk and Evans blue (EB) dye as a subject. The EB dye adsorption percentage was determined to be 95.95% with 72.0 mg/g adsorption amount at optimal conditions of pH 2 and 40 °C. The second-order kinetic model fit the experimental data the best. Additionally, the results indicated that the Sips isotherm model fits the experimental data better and that the experiment involved single-layer adsorption on the adsorbent surface. A non-linear regression of the van’t Hoff plot gave negative values of Gibbs free energy (−39.38 to −41.48 kJ/mol) at all the temperatures studied (from 20 to 60 °C), indicating that the adsorption process is spontaneous and feasible. A negative value for the enthalpy (ΔH o =−23.37kJ/mol) indicated that the adsorption was exothermic, and the positive value of (ΔS o =54.55kJ/mol·K) concludes the nature of adsorption of Evans blue dye by Durian husk likely to follow a physisorption adsorption mechanism.