Kinetics and mechanisms of biosorption of copper ion onto waste yeast (S. cerevisiae)
Heavy metals are the most common pollutants found in industrial effluents. Several chemical treatment methods are used to remove heavy metals from aquatic solutions. Recently, biosorption process which utilizes various microbial materials (bacteria, fungi, yeasts, algae etc.) has been preferred to remove pollutants. In this study, waste yeast taken from yeast factory in Turkey was used as (working volume of 100 ml) biosorbent in erlenmeyer batch experiments by using temperature controlled shaker and copper (II) ion biosorption was examined. The effects of initial pH (2, 3, 4, 5, 6, 7), initial copper concentrations (25, 50, 75, 100, 150, 200, 250, 300 mg L?1), biosorbent amount (1, 3, 5, 7 10 g L?1), contact time (5, 10, 15, 30, 45, 60, 90, 120, 240, 1440 min.) and temperature (20, 30, 40, 50 °C) parameters on to biosorption process were investigated. Optimum biosorption capacity was found as pH 5, 100 mg L?1 of initial copper concentration, 10 g L?1 biosorbent amount and 1440 min. of contact time. The experimental equilibrium data fitted to Freundlich and Langmuir adsorption isotherm models. Freundlich models fitted better than Langmuir models. The maximum adsorption capacity of waste yeast was determined as 7.94 mg g?1and Freundlich isotherm values n and kf were found to be 1.55 and 0.21 respectively. Pseudo-second order kinetic model was suitable for biosorption kinetics. According to calculated thermodynamic parameters (?H, ?G and ?S), biosorption of copper onto waste yeast was exothermic. As a conclusion; it was found that copper (II) removal by using waste yeast was low. Activation of biomaterial by pretreatment can be resulted in increasing of removal rate. Use of waste materials in pollution control is important for economic issue. © Springer Science+Business Media Dordrecht 2015.