Biorecovery of nanogold and nanogold compounds from gold-containing ores and industrial wastes.

In nature, microorganisms developed at various places and adapted to the various weather and geological conditions. Microorganisms participate in geological transformations leading to the dissolution of some minerals and conversion to others. While some microorganisms with their metabolic activity increase the mobility of metals, others cause precipitation of metals and the formation of new minerals. These biogeochemical interactions found practical application in the recovery of metals. In the article, the proposals for improvement of existing engineering commercial processes for recovery of metals are given which can enable the formation of nanogold and nanogold compounds.Key points• Amino acids in pretreatment can increase the dissolution of the layer around the gold.• Amino acids in the complexing stage can increase gold leaching.• After the complexing stage, the bionanosynthesis of gold and its compounds is possible.

Electrochemical behavior of pyrite in sulfuric acid in presence of amino acids belonging to the amino acid sequence of rusticyanin.

The impact of different concentrations of three amino acids (cysteine, histidine and methionine) which are part of the amino acid sequence of rusticyanin on dissolution of pyrite is investigated by the application of electrochemical techniques. Cyclic voltammetric studies conducted in the anodic direction from corrosion potential have shown that in the vicinity of corrosion potential, histidine and methionine do not influence dissolution of pyrite independently on their concentrations. On the other hand, cysteine and solutions of these amino acids in the molar ratios Cys:His:Met/1:1:1 and Cys:His:Met/1:2:1 accelerate dissolution at concentrations 10-2 mol L-1 and 10-3 mol L-1. Potentiodynamic polarization measurements showed that methionine does not affect the anodic and cathodic dissolution at all concentrations, while histidine does not affect significantly on the anodic dissolution at all concentrations. Cysteine and solutions of three amino acids in the molar ratio Cys:His:Met/1:1:1 and Cys:His:Met/1:2:1 cause intensive cathodic inhibition and anodic activation at concentrations 10-2 mol L-1 and 10-3 mol L-1 respectively.