Biosorption of dye by immobilized yeast cells on the surface of magnetic nanoparticles

Abstract

Bioremediation has been considered as an efficient environmental pollution control technique. It relies on microbial cells like yeasts which are unicellular organisms that are widely used due to their availability, easily cultured, economical, and eco-friendly. The immobilization of living cells on the magnetic nanoparticles surface is a novel technique to obtain nanobiocatalyst. In this work, yeast cells of Saccharomyces cerevisiae were immobilized on the surface of Fe3O4 magnetic nanoparticles (MNPs) as a biosorbent to remove methyl orange (M.O) dye from aqueous solution in a batch system through biosorption mechanism. MNPs were characterized using XRD and SEM. FTIR was used to characterize the biosorbent before and after biosorption. The experiments were carried out using various factors such as contact time, pH, M.O concentration, biosorbent dosage, and temperature. The results indicated that significant removal efficiency of 96.52 % was obtained at the optimum conditions of pH 6.5, 50 mg/l M.O initial concentration, 1.5 g/l biosorbent dosage, 110 rpm shaker, and 35 °C temperature. Adsorption isotherm studies illustrated that the data of biosorption of M.O dye from aqueous solution followed the Freundlich model with a correlation coefficient of R2 > 0.99. The values of biosorption thermodynamic parameters were estimated and the results showed that the biosorption mechanism of M.O dye was exothermic due to the negative value of ΔHo (-7.8737 KJ/mol), and spontaneous due to the negative values of ΔGo (−5108.22, −6286.16, −7475.21) at various temperatures. Moreover, the positive value of ΔSo (28.47 J/mol) pointed out to an increment in randomness at the interface of the aqueous solution-biosorbent.