Biosynthesis of copper nanoparticles from copper tailings ore-An approach to the 'Bionanomining'

Nanotechnology is a discipline that studies the behavior of materials on a nanometric scale. These materials are known to have a wide range of applications due to the outstanding optoelectronic, magnetic, and thermal properties that their scale provides. However, one of the current challenges associated with nanotechnology lies in how nanomaterials are generated. Within the new synthesis trends, biological routes have been proposed as an alternative that requires less polluting organic solvents and less energy consumption. The biosynthesis of metallic nanoparticles is a Bottom-up method that requires precursors, which have mostly been described as pure solutions. However, in the present work and approaching the concept of 'Bionanomining', the use of a real effluent obtained from the leaching of sulfide ore tailings is studied for the biosynthesis of copper nanoparticles. For this purpose, the bacterial biomass of Pseudomonas stutzeri was used as a bioreducing agent. The leaching of the chalcopyrite-bearing tailings achieved a copper recovery of 50% in 8 h, thanks to sodium nitrate that acted as an oxidizing agent. The copper concentration was increased by solvent extraction, allowing a solution of 700 mg/L of copper to be achieved. In the biosynthesis of nanoparticles, the experiments were carried out at room temperature and pressure for 48 h, using two different copper precursor solutions. In the first stage, a pure solution was used to determine an adequate copper concentration and biomass dosage, which were 381 mg/L and 1050 mg, respectively. In an advanced approach, the solution obtained from the treated tailings was employed for the biosynthesis, obtaining nanoparticles in the two resulting streams: a solid dead biomass and sodium sulfate solution with 2.7% and 0.27% copper nanoparticles, respectively. These nanoparticles are spherical and with a size between 1 and 2 nm.

Automated summary

Nanotechnology studies the behavior of materials on a nanometric scale and proposes biological routes as an alternative method for energy-saving and pollution reduction. By using real effluent for biosynthesis, copper recovery was achieved with different streams of nanoparticles.