BIOSORPTION OF LEAD (II) AND CADMIUM (II) FROM AQUEOUS SOLUTION USINGRAW AND PRETREATED ASPERGILLUS NIGER.

Abstract

Heavy metals present in wastewater are found to be detrimental not only to the environment but also to the health of human beings. The biosorption of lead (II) and cadmium (II) from aqueous solution by raw and NaOH--pretreated fungal biomass of Aspergillus niger was investigated. Parameters affecting biosorption such as pH, agitation rate, and metal ions were examined. It was found that the initial pH of the solution strongly affected the degree of biosorption. Metal solutions with pH of 5 and 4 yield the highest percentage biosorption of Aspergillus niger for mono--metal solutions and bi--metal solutions, respectively. The agitation rate of 400 rpm and 150 rpm yield the highest percentage removal on single metal ions and combined metal ions, respectively. Moreover, the lead and cadmium adsorption by pretreated Aspergillus niger was higher than that of raw Aspergillus niger in all cases. The kinetics of heavy metal biosorption matched second order reaction model. The biosorption isotherms indicated that the biosorption of Cd (II) and Pb (II) can be fitted with the Langmuir equation indicating that the biosorption mechanism of Cd (II) and Pb (II) by Aspergillus niger was chemisorption.