Biosorption of As(III) ions from aqueous solution using dry, heat-treated and NaOH-treated Aspergillus nidulans

The biosorption of As(III) ions on dry, heat-treated and NaOH-treated Aspergillus nidulans in aqueous solutions was studied. The effect of pH (2-6), temperature (25, 30, 35, 45 degrees C), and initial concentration (250-700 mg L-1) of As(III) ions were investigated in a batch system. The maximum biosorption rate of As(III) ions on the tested biosorbent were obtained at pH 4 and 35 degrees C in about 240 min. The maximum biosorption capacities of dry, heat-treated and NaOH-treated fungal biomass were 127, 178 and 166 mg g-1 of dry biomass, respectively. The As(III) adsorption data were analyzed using the first- and the second-order kinetic models. The experimental results suggest that the second-order equation is the most appropriate equation to predict the biosorption capacity by dry, heat-treated and NaOH-treated Aspergillus nidulans. Langmuir and Freundlich isotherms were used to evaluate the data, and the regression constants were derived. Biosorption equilibrium data were best described by the Langmuir isotherm model followed by the Freundlich model.