Process for the production of metallic gold nanoparticles from na efluente arising from acid mine drainage bioremediation

Abstract

The present request describes a process to obtain metallic gold nanoparticles from an effluent containing sulfide, resulting from a bioremediation process of acid mine drainage (AMD) based on the use of sulfate-reducing bacteria. The disclosed process consists of the effluent addition to a gold solution in concentrations between 20-250 mg/L, in batch or continuous systems, allowing to obtain nanoparticles of Au(0) with a yield of 70-100%.

1 . Process for the production of metallic gold nanoparticles using a sulfide-rich effluent from the bioremediation of acid mine drainage with sulfate-reducing bacteria, comprising the following steps:
 effluent's filtration with a 0.22 μm filter;   Effluent's addition, drop by drop and under stirring, to an AU(III) aqueous solution with a concentration of 20-250 mg/L;   removal of AU(0) nanoparticles as a precipitate followed by washing and drying.   
     
     
         2 . Process according to  claim 1  in which an aqueous solution comprising 20-250 mg/L of AU(III) is added drop by drop and under stirring to the effluent. 
     
     
         3 . Process according to  claim 1  wherein the effluent's addition to the aqueous solution comprising AU(III) or the addition of the solution comprising AU(III) to the effluent occurs in batch or in continuous. 
     
     
         4 . Process according to  claim 1  in which the continuous system is coupled to the bioremediation process, wherein the bioreactor effluent is added drop by drop at a constant flow to the aqueous solution comprising AU(III) placed under stirring in a reactor downstream to the bioremediation process. 
     
     
         5 . Process according to  claim 1  wherein the effluent is added to the AU(III) aqueous solution until an excess of sulfide, in comparison to the metal ion, can be enough to guarantee complete reduction of AU (III) to AU (0).