Baker’s yeast-MnO2 composites as biosorbent for Malachite green: An ecofriendly approach for dye removal from aqueous solution

Abstract

In this study, baker’s yeast-MnO₂ composites, produced by direct oxidation of yeast with KMnO₄ under acidic conditions, were used as biosorbent to remove the triphenylmethane dye Malachite green (MG) from an aqueous solution. Parameters that influence the adsorption process, such as pH, contact time, temperature, initial dye concentration and biosorbent dosage, were evaluated in batch experiments. The optimum removal of MG was found to be  86.7 mg g^-1 at pH 10, 1.0 g L^-1 of biomass dosage and 45°C. The kinetic data of dye removal was better described by the pseudo-second-order model. The adsorption process followed the Langmuir isotherm model and the maximum biosorption capacity was estimated to be  243.9 mg g^-1 (at 25°C). The negative values of ∆G° and the positive value of ∆H° indicated that the MG biosorption onto yeast-MnO₂ composites is spontaneous and endothermic. Fourier transform infrared spectroscopy (FTIR) indicated that the nano-MnO₂ particles deposited on yeast-MnO₂ composites surface facilitated the MG adsorption. It was concluded that baker’s yeast-MnO₂ composites have potential for application as adsorbent for removal of MG from aqueous solution.