PRECIOUS METAL RECOVERY METHOD USING COMPOSITE

摘要

PROBLEM TO BE SOLVED: To provide a method for recovering precious metals in an industrially usable form.SOLUTION: A precious metal recovery method for recovering precious metals as nanoparticles comprises bringing a sample solution in which precious metals are dissolved into contact with a composite of a metal reducing substance produced in a culturing process of reducing bacteria and culture medium components to adsorb the precious metals existing in the sample solution on the composite, adjusting the hydrogen ion exponent of the composite having adsorbed the precious metals to a pH of 1.5 or less by an inorganic acid, whereby the composite is dissolved to desorb the precious metals as nanoparticles, and subjecting the precious metal nanoparticles and a solution of the composite to solid-liquid separation to recover the precious metal nanoparticles. The reducing bacteria are iron-reducing bacteria belonging to the genus Shewanella. The composite is a lattice-like structure having voids of 1-20 nm, and the precious metal nanoparticles have a particle size of 1-20 nm.