sc1c01705_si_001.pdf (120.38 kB)
Novel Extraction Process for Gold Recovery from Thiosulfate Solution Using Phosphonium Ionic Liquids
journal contribution
posted on 2021-06-07, 18:38 authored by Harshit Mahandra, Fariborz Faraji, Ahmad GhahremanA novel
and sustainable technology to recover gold from thiosulfate
medium using ionic liquids, i.e., Cyphos IL 101 (Cy IL 101) and Cyphos
IL 102 (Cy IL 102) diluted in toluene, has been developed. Gold was
extracted into the ionic liquid phase as [{P66614+}3{Au(S2O3)23–}] and stripped using NaCl solution. The recyclability of ionic liquids
has shown promising recirculation of the solvents for the extraction
of gold from thiosulfate medium. Gold was quantitatively extracted
from 0.2 mol/L sodium thiosulfate initially containing 10 mg/L gold
at pH = 9.0 with 1.25 mmol/L ionic liquid (Cy IL 101 or Cy IL 102)
in one stage at A/O = 2, whereas total gold stripping with 1.5 mol/L
NaCl also needed one stage at A/O = 1. Using a high A/O ratio in the
extraction stage (A/O = 10) and low (A/O = 1/10) in the stripping
stage confirmed the economic and environmental viability of the process.
The results revealed that Cy IL 101 presents slightly better behavior
toward gold recovery than Cy IL 102 and is a viable and promising
alternative to recover gold from the thiosulfate medium on a pilot
scale. The overall study confirmed the suitability of the developed
scheme for industrial application to provide economic and environmental
benefits.