SERS and electrochemical studies of the gold–electrolyte interface under thiosulfate based leaching conditions

RDE study of thiosulfate oxidation on gold

“…Changes at gold-solution interface also take place during longterm (about 60-420 min) exposure of gold under thiosulfate-based leaching conditions. Under these conditions the SERS spectra reveal the presence of sulfide ions or elemental sulfur, tetrathionate, Au S 2 O 3 ð Þ 3À 2 , and possibly adsorbed sulfite ions as a product of thiosulfate decomposition [11]. However, it should be noted that the changes in the composition of the gold surface layer observed under the indicated conditions seem unable to explain the current drop on the curves shown in Fig.…”

Anode current on gold in mixed thiosulfate-sulfite electrolytes

“…The polysulfide layer on gold can be formed not only by electrochemical oxidation of thiosulfate but also by its long-lasting exposure to these solutions. According to SERS studies of the gold-electrolyte interface under thiosulfate-based leaching conditions [26][27][28], the products of thiosulfate decomposition are monoatomic and polymeric sulfur. These products of thiosulfate decomposition are formed after A C C E P T E D M A N U S C R I P T long-lasting (more than 60 min) metal-solution contact.…”

The effect of tetrathionate on the anodic process of gold thiosulfate leaching

“…It was observed that that the addition of tetrathionate and trithionate would reduce the gold oxidation rate by 10-20%. 13 In the presence of ammonia, Jeffrey et al reported new bands positioned at 380 and 1,029 cm −1 as higher polythionates (larger than tetrathionates). 15 Polythionates in a leaching solution may alter the composition of the passive film, although they were not adsorbed on the gold surface.…”

“…13 Chu et al also studied the effects of oxygen addition on the gold dissolution rate in a solution of thiosulfate and various polythionates. The decrease of 10-20% in the leaching current was observed by Baron, when the 10-mM tetrathionate and trithionate were added to the 0.1-M S 2 O2-3+ 1 × 10 −4 -M NaOH solution.…”