Sustainable and selective bioadsorption of gold and platinum using the fungus aspergillus niger in binary aqueous systems

The leaching of minerals and recovering precious metals with microorganisms is a technique based on using non-pathogenic bacteria, yeasts, and fungi. The capacity of some biomasses to recover metals from solutions is the basis for innovation recovery technologies; for instance, to adsorb precious metals dissolved in a liquid medium by using the fungus Aspergillus niger. In this research, the bioadsorption of gold and platinum from a liquid medium was investigated using dead biomass of the fungus Aspergillus niger. The chemical and physical characterization of the biomass (before and after contact) and the residual liquid were carried out. The analysis techniques used were FT-IR, atomic absorption spectroscopy, and scanning electron microscopy. Through the bioadsorption of these metals (in a batch system), recoveries from 50 and up to 100 %, depending on the pH (from 0.01 to 0.02 mg/g, respectively), were obtained after 120 minutes of contact of 20 mg/l of each metal (separately) with the fungus. This demonstrates that the recovery highly depends on biomass's active (functional) sites.