Removal of a low-molecular basic dye (Azure Blue) from aqueous solutions by a native biomass of a newly isolated Cladosporium sp.: Kinetics, equilibrium and biosorption simulation

The biosorption of Azure Blue from aqueous solution was investigated for the first time using a new isolated Cladosporium Ch2-2. The biosorption studies were carried out under various parameters, such as initial dye concentration, pH, biosorbent dosage and different cations. High dye removal yield was achieved at pH 8, which was consistent with the pH of most of the wastewater. The maximum biosorption occurred at the pH value of 8.0 for Azure Blue. Mg2+ and EDTA had a positive effect on dye biosorption process. Equilibrium time was attained at 60 min for the dye concentrations of 30–100 mg/L. The adsorbent dosage of 0.1 g in 20 ml was found to be optimum for increased dye uptake. The Langmuir isotherm model better described the process of dye uptake than the Freundlich model. The maximum monolayer biosorption capacity of the biosorbent was 51.4 mg/g. The pseudo-second order kinetic model adequately described the kinetic data. Finally the proposed biosorbent was successfully used for the decolorization of Azure Blue in simulated wastewater conditions. The biosorption results suggested that this environmentally friendly and efficient biosorbent may be useful for the removal of basic dyes from aqueous solution.

► The biosorption of Azure Blue from aqueous solution was investigated using a low-cost and eco-friendly biosorbent, Cladosporium Ch2-2 for the first time. ► High dye removal yield was achieved at pH 8.0, which was consistent with the pH of most of the wastewater. ► Effects of different cations and reagents were tested which showed that Mg2+ as well as EDTA could increase the adsorption. ► The Langmuir isotherm model better described the process of dye uptake than the Freundlich model, and the biosorption rates were found to be consistent with the pseudo-second-order model.