Preparation of gold powders by means of redox-active extractive systems

Solvent extraction of gold by means of two S-decyldithizone derivatives was studied, where partial precipitation of the gold and oxidation of the extractants were observed. Gold was recovered from the loaded organic phases by reduction as fine particles, and the extractants could be reduced and fully regenerated. The efficiency of extractant regeneration increased with increasing ascorbic acid concentration. In the case of reduction with sodium borohydride, the best reduction efficiency was achieved by use of an alkaline borohydride solution. A scanning electron microscopy method has been used to characterise the precipitated gold powders. The presence of the carboxylic group on one of the aromatic rings of the substituted S-decyldithizone greatly influences the morphology and size of the produced metal particles.