Biosorption of Pb~(2+) by extracellular polymeric substances produced by Aspergillus fumigatus

CER extraction was used to extract extracellular polymeric substances from Aspergillus fumigatus.The biochemical composition of the EPS was determined.The adsorption of Pb2+ by the EPS was investigated and the equilibrium and the mechanism of biosorption of Pb2+ by EPS are discussed.The results showed that the CER process extracted high amounts of the EPS carbohydrate with hardly any cell lysis.The biosorption equilibrium time was about 3 hours.At pH 6.5,the lead removal efficiency could reach 73.48%.Both the Langmuir isotherm and Freundlich isotherm models could describe the biosorption equilibrium well,but the Langmuir isotherm fit better.The maximum uptake capacity of lead was estimated to be 32.22 mg·g-1 EPS.Analysis of FTIR spectra demonstrated that hydroxyl,carboxyl and C—O—C groups of the polysaccharide were the main functional groups in the reaction between Pb2+,and the binding capacity of protein to Pb2+ was weak.