Bionanomining of copper-based nanoparticles using pre-processed mine tailings as the precursor

Area of Science:

• Nanotechnology
• Environmental Science
• Microbiology

Background:

• Conventional methods for copper nanoparticle (CuNP) synthesis are often environmentally hazardous and costly.
• Bacterial synthesis offers a sustainable, single-step, bottom-up approach for producing stable metal nanoparticles.
• Utilizing pre-processed mining tailings as a precursor presents an opportunity for waste valorization in nanoparticle production.

Purpose of the Study:

• To investigate the biosynthesis of copper nanoparticles (CuNPs) using Rhodococcus erythropolis ATCC4277 and pre-processed mining tailings.
• To evaluate the influence of process parameters, such as pulp density and stirring rate, on CuNP characteristics.
• To assess the potential biomedical (antibacterial, cytotoxicity) and photocatalytic applications of the synthesized CuNPs.

Main Methods:

• Biosynthesis of CuNPs was performed in a stirred tank bioreactor using Rhodococcus erythropolis and mining tailing precursor.
• Experiments were conducted at 25°C with controlled O2 flow rate (1.0 L min⁻¹) and pH (7.0) for 24 hours.
• Factor-at-time design was employed to study the effect of pulp density (25 g L⁻¹) and stirring rate (250 rpm) on particle size.

Main Results:

• Stable CuNPs with an average hydrodynamic diameter of 21 ± 1 nm were synthesized.
• The synthesized CuNPs exhibited significant antibacterial activity against Escherichia coli (60% growth inhibition) and low cytotoxicity against Murine Embryonic Fibroblast cells (70-75% viability).
• CuNPs demonstrated effective photocatalytic activity, degrading approximately 65% of methylene blue dye in 4 hours.

Conclusions:

• Bacterial synthesis of CuNPs using Rhodococcus erythropolis and mining tailings is an environmentally sound and cost-effective method.
• The synthesized CuNPs possess valuable properties for potential applications in biomedicine and environmental remediation (photocatalysis).
• This approach offers a sustainable route for transforming mining waste into functional nanomaterials.