Abstract

Cadmium and chromium adsorption by fresh and dried biomasses of Curvularia pallescence were investigated. The biosorption conditions, such as pH, temperature, contact time, initial metal concentration, and biomass bulk density were studied. The optimum pH values for cadmium uptake by fresh and dried biomass were 8.0 and 5.0, respectively. While, the optimum pH values for chromium uptake by fresh and dried biomass were 4.0 and 5.0, respectively. The optimum temperature for maximum metal uptake was found to be at 30˚C. Maximum cadmium and chromium binding capacity by fresh and dried biomass was obtained at concentrations 50 and 200 mgL-1, respectively. The best adsorption capacity of cadmium was obtained at 60 min. contact time. While for chromium it was obtained at 90 min. The binding capacity was decreased with increasing the biomass bulk density. The best binding capacity was obtained by using 0.5g fresh biomass and 0.05 g dried biomass using 20 ml of 200 mg/L cadmium or chromium. Treating the fresh mycelium by NaOH increased its binding capacity and therefore the biosorption efficiency whereas, treating with HCl decreased its binding capacity.

Key words: Curvularia pallescence; Biosorption; Heavy metals; binding capacity