Adsorptive removal of cochineal red a dye from aqueous solutions using yeast

Abstract

This paper presents an experimental study on Cochineal Red A dye adsorptive removal by yeast. Batch equilibrium and kinetic tests were conducted in constant temperature of 30 ◦ C for the dye’s initial concentration range of 0.02–0.50 g/L (pH = 3 and 10) and 0.02–0.35 g/L (pH = 7 : 6 ). The equilibrium was reached after 105–120 min. Yeast demonstrated the adsorption capacity of 10.16 mg/g for acidic environment (pH = 3 ) and slightly lower values (8.13 mg/g and 8.38 mg/g respectively) for neutral (pH = 7 : 6 ) and alkaline environment (pH = 10 ). The experimental equilibrium results were fitted with Langmuir, Freundlich, Sips and Toth isotherm models. Most of them (Freundlich model being the exception) were proven sufficient for the experimental data correlation. The adsorption kinetic studies showed that the pseudo-second order model fits better the experimental data than the pseudo-first-order model. Results achieved from intra-particle diffusion model indicate that powdered yeast are a nonporous adsorbent. The percentage of solution discoloration reached a maximum value of 75% at pH = 3 for an initial dye concentration of 0.02 g/L.