DECOMPOSITION OF THIOCYANATES DURING ELECTROLYSIS

The fate of thiocyanate ion during electrolytic silver recovery operat ions was studied. The experimental conditions for these laboratory tes ts were chosen to simulate conditions that might be applied in the rec overy of silver in the photographic industry. A photographic fixer sol ution spiked with a one molar concentration of ammonium thiocyanate wa s electrolyzed in a commercially available rotating cathode silver rec overy cell at a current density of 20 mA/cm(2). A low concentration of hydrogen cyanide gas (generally <1 ppm) was detected in the headspace of the electrolytic cell during the constant current electrolysis. an alysis of the fixer solution after electrolysis also confirmed the pre sence of cyanide in the liquid phase.