Biosorption of lead(II) from aqueous solution by lactic acid bacteria

Area of Science:

• Environmental Microbiology
• Biotechnology
• Water Treatment

Background:

• Lead (Pb(II)) contamination in aqueous solutions poses significant environmental and health risks.
• Biosorption using microbial biomass offers a sustainable and cost-effective approach for heavy metal removal.
• Lactic acid bacteria, such as Lactobacillus brevis, are abundant and possess biosorptive capabilities.

Purpose of the Study:

• To investigate the biosorption efficiency of Lactobacillus brevis for Pb(II) removal from aqueous solutions.
• To determine the optimal conditions for Pb(II) biosorption.
• To analyze the adsorption isotherms, kinetics, and thermodynamics of the biosorption process.

Main Methods:

• Studied the effects of pH, contact time, initial Pb(II) concentration, bacterial concentration, rotation speed, and temperature.
• Evaluated biosorption using isotherm models (Redlich-Peterson, Langmuir, Freundlich, Temkin) and kinetic models (pseudo-second-order, Elovich).
• Determined thermodynamic parameters to assess the feasibility and nature of the adsorption process.

Main Results:

• Optimal biosorption conditions were identified as pH 6, 120 rpm, 3 g/L bacterial concentration, 40°C, and 12 h contact time.
• The maximum equilibrium adsorption capacity reached 53.632 mg/g.
• Adsorption followed Redlich-Peterson, Langmuir, Freundlich, and Temkin isotherms, and pseudo-second-order and Elovich kinetics, suggesting a combination of chemisorption and physisorption.

Conclusions:

• Lactobacillus brevis is a highly effective biosorbent for Pb(II) removal from contaminated water.
• The binding energy indicates a mixed adsorption mechanism.
• Thermodynamic analysis confirms the spontaneous and endothermic nature of the Pb(II) biosorption process.