BIOSORPTION OF LEAD BY ASPERGILLUS NIGER: EQUILIBRIUM, KINETICS AND PROCESS MECHANISM P. B. KODOLIKAR 1 , S. P. KODOLIKAR 2 , D. S. BHATKHANDE 3 & S. S. GORE 4 1 AS, Honeywell Automation India Ltd., Pune, Maharashtra, India 2 Department of Chemical Engineering, Sinhgad College of Engineering, Pune, Maharashtra, India 3 Department of Chemical Engineering, Vishwakarma Institutes, Pune, Maharashtra, India 4 Department of Microbiology, Fergusson College, Pune, Maharashtra, India ABSTRACT This paper describes the equilibrium, kinetics and process mechanism studies on biosorption of lead ions from aqueous solution using ‘Aspergillus niger ’ in a batch process. The results indicate that biosorption of lead is influenced by various experimental parameters such as initial concentration of lead, amount of biomass used, variation in pH of solution and agitation speed. The lead uptake by biomass was quantitatively evaluated using sorption isotherms like Freundlich and Langmuir isotherm. The results indicate that Langmuir isotherm model describes the present data very well indicating favorable biosorption. Since the process follows pseudo second order kinetics, the mechanism of biosorption of lead by Aspergillus niger can be explained by shrinking core model. KEYWORDS: Biosorption, Lead Removal, Aspergillus niger INTRODUCTION The presence of heavy metals like lead, zinc, nickel, mercury, cadmium etc. in aquatic environment has been of great concern because of an increase in discharge, their toxic effects and other adverse effects on receiving water. To solve the water pollution problem by toxic heavy metal contamination resulting from human technological activities has for long presented a challenge. With well defined point sources of lead contamination, the major spread of lead in environment has been curbed by introduction of leaded gasoline, mining operations, refining ores, sludge disposal, automobiles and battery manufacturing, electronics and electrical equipments, e-wastes, mobiles, car batteries, television sets etc .[4,8,18,20] Biosorption is defined as the ability of biological materials to accumulate heavy metals from waste water through metabolically mediated or physico-chemical pathways of uptake [18]. The uptake of heavy metals by biomass can reach up to 50% of biomass dry weight. New biosorbents can be manipulated for better efficiency and multiple reuses to increase their economic attractiveness [2, 4] . The biomass used for this purpose must come from nature or even has to be a waste material like sea weeds, moulds, yeasts, bacteria, crab shells etc. The mechanism involved due to interaction between a metal ions and biomass are complex in nature. The complex structure of microorganisms implies that there are many ways for the metal to be taken up by the microbial cell. It has been postulated that the different metal binding mechanisms active in biosorption are chemisorptions, physical adsorption, and micro precipitation. MATERIALS AND METHODS Preparation of Biomass Aspergillus niger of NICM grade From National Chemical Laboratory, Pune was used for the experimentation. Aspergillus niger was obtained on slants, which was cultivated in liquid medium using shake flask method. Spores and International Journal of Bio-Technology and Research (IJBTR) ISSN 2249-6858 Vol. 3, Issue 4, Oct 2013, 77-90 © TJPRC Pvt. Ltd.