Biosorption of remazol orange RR from aqueous solution: kinetic, equilibrium and thermodynamic studies

Remazol Orange RR (RORR) is one of the most frequently used textile dye which causes environmental pollution. In the present study, parameters affecting the RORR biosorption with dead Saccharomyces cerevisiae yeast were investigated. The maximum %RORR removal was found to be 84.9% at 2 g/L biosorbent dosage, 200 mg/L initial dye concentration, pH 3.0, and 25°C. RORR biosorption with S. cerevisiae was expalined by pseudo-second-order kinetics model and Langmuir adsorption isotherm with correlation coefficient (R2) of 0.99 and 0.87, respectively. The enthalpy change (ΔH), entropy change (ΔS) and activation energy (Ea) were determined as 35.9 kJ/mol, 88.1 kJ/mol K and 3.36 kJ/mol, respectively. In addition, Gibbs free energy change was calculated as –10.04, –8.03 and –8.33 kJ/mol for 298, 308 and 318 K, respectively. It is concluded that the biosorption of RORR by S. cerevisiae occurs mainly by physical adsorption through a spontaneous process. The high dye removal and biosorbent capacity indicated that S. cerevisiae is a promising biosorbent for dye removal.