Performance, kinetics and equilibrium in biosorption of anionic dye Acid Red 14 by the waste biomass of Saccharomyces cerevisiae as a low-cost biosorbent

Equilibrium, kinetics and thermodynamic studies on the removal of Acid Red 14 (AR14) anionic dye by biosorption onto dried waste biomass of Saccharomyces cerevisiae have been investigated. In batch experiments, the parameters studied included the effect of the dye concentration, temperature, contact time, adsorbent dosage, agitation speed, pH, and salt concentration. The pseudo-first-order and pseudo-second-order kinetic models were applied to the experimental kinetic data. High correlation coefficients with low standard deviations favor the pseudo-second-order model for the present systems. The biosorption process was found to be chemical adsorption and it has an endothermic nature. The entropy (∆S◦ ), enthalpy (∆H◦ ), and activation energy (Ea) were estimated as 49.51 J/mol K, 16.36 kJ/mol, and 10.44 kJ/mol, respectively. The positive values of standard Gibbs free energy change (∆G◦ ) indicate feasible and nonspontaneous adsorption of AR14 on S. cerevisiae. Langmuir, Freundlich, Temkin, and Halsey adsorption models were used for the mathematical description of the batch biosorption equilibrium data and model constants were evaluated. The Langmuir model gives the best agreement with obtained experimental isotherms data. A design for a batch adsorption unit using data from isotherm studies was made.