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Lead biosorption study with Rhizopus arrhizus using a metal-based titration technique.
Ghinwa Naja1, Christian Mustin, Jacques Berthelin
1Department of Chemical Engineering, McGill University, Montreal, Quebec, Canada.
Journal of Colloid and Interface Science
|June 28, 2005
Summary
Rhizopus arrhizus fungal biomass effectively sorbs lead via carboxylic groups, with adsorption dominating at low concentrations and micro-precipitation occurring at higher lead levels. This study details lead biosorption mechanisms.
Area of Science:
- Biotechnology
- Environmental Science
- Biochemistry
Background:
- Biosorption is a key process for removing heavy metals from wastewater.
- Understanding the specific mechanisms of lead sorption by fungal biomass is crucial for optimizing bioremediation strategies.
Purpose of the Study:
- To elucidate the sorption mechanisms of lead (Pb) by Rhizopus arrhizus fungal biomass.
- To differentiate between adsorption and precipitation processes in lead biosorption.
Main Methods:
- Potentiometric titration (acid-base and metal-based) to analyze sorption reactions.
- Infrared spectroscopy (IR) and Transmission Electron Microscopy with Energy Dispersive X-ray Analysis (MET-EDAX) to confirm chemical bonds and binding sites.
Main Results:
- Lead sorption is a sequential process involving various binding sites, primarily carboxylic groups, followed by phosphates and sulfonates.
- Surface micro-precipitation of lead occurs and is sequential to adsorption, becoming dominant at higher lead concentrations (>10(-5) M).
- Adsorption is the primary mechanism at low lead concentrations (<10(-6) M).
Conclusions:
- Rhizopus arrhizus exhibits complex lead sorption behavior involving both adsorption and micro-precipitation.
- The affinity of lead to binding sites is influenced by proton/counter-ion association and site spatial distribution.
- Specific functional groups, particularly carboxylic ones, play a significant role in lead binding by the fungal biomass.