Biosorption of Reactive Yellow 145 Dye by Dried Penicillum restrictum: Isotherm, Kinetic, and Thermodynamic Studies

Removal of dyes from wastewaters causes a big concern from the environmental point of view due to their extreme toxicity towards aquatic life and humans. Commonly used traditional methods to treat these effluents are ineffective because dyes show resistance to many chemicals, oxidizing agents, and light. In this context, the biosorption process has attracted great attention in recent years since they utilize not only cheap plant materials but also a wide variety of microorganisms as biosorbing agents, displaying a high dye-binding capacity. In this study, biosorption potential of dried Penicillum restrictum (DPR) for Reactive Yellow 145 (RY 145) was studied with respect to pH, equilibrium time, and temperature to determine equilibrium and kinetic models. The most suitable pH and equilibrium time were determined as 1.0 +/- 0.05 and 75 min respectively, at a biomass dosage of 0.4 mg L-1 and 20 +/- 0.5 degrees C. Data obtained from batch studies fitted well with the Dubinin-Radushkevich (D-R) followed by the Freundlich and Langmuir isotherm models. Maximum uptake capacities (qm) of DPR for the dyestuff (RY 145) were 109.7, 115.2, and 116.5 mg g(-1) biomass at temperatures of 20, 30, and 40 +/- 0.5 degrees C, respectively. The overall biosorption process was best described by the pseudo-second-order kinetic model. Gibbs free energy changes were calculated as -384.6, -273.5, and -245.9 J mol L-1 at 20, 30, and 40 +/- 0.5 degrees C, respectively.