Biosorption of lead, mercury, and cadmium ions by Aspergillus terreus immobilized in a natural matrix

Our aim was to investigate the biosorption of Pb²⁺, Hg²⁺, Cd²⁺ from aqueous solution by Aspergillus terreus (both free and immobilized on loofa sponge discs). Our results show that the adsorption capacity of fungal biomass on loofa sponge (FBLS) is superior to free fungal biomass (FFB). The adsorption selectivity by FBLS was in the order Pb²⁺>Hg²⁺>Cd²⁺. The maximum metal ions adsorbed was 247.2,37.7, 23.8 mg/g FBLS for Pb²⁺, Hg²⁺ and Cd²⁺, respectively. Metal uptake by FBLS was affected by the pH of the metal solution, but independent of temperature (10-50°C). The Langmuir model was more suitable than the Freundlich model to describe the biosorption process of FBLS. The regenerated FBLS was found to be effective for repeated use for five cycles without significant loss in adsorption capacity. This research demonstrates that FBLS possesses excellent capacity for Pb²⁺ biosorption from aqueous solution and industrial wastewaters.