Removal of Cr(VI) from solution by free and immobilised spores of Aspergillus niger

Despite the current interest in microbial methods for the detoxification of effluents, relatively little work has focused on the characterisation of metal uptake by small Aspergillus niger spores, particularly for heavy metals present at different and low concentrations. The objective of this study was to determine the ability of A. niger spores (free spores and as immobilised biosorbent) to remove toxic metals from an industrial wastewater as a batch system. The simultaneous influences of the mass of pH and biomass on the ability of spores to uptake of Cr(VI) were analysed. The free and immobilised biosorbent removed Cr(VI) efficiently with a maximum metal removal capacity of 55 and 40 mg/g, respectively. The biosorption mechanism was also investigated using Fourier transfer infrared and scanning electron microscopy. Immobilised spores of A. niger were more stable in solutions at different pH levels and allowed easier separation from aqueous solution than free spores, suggesting significant potential for future industrial application.