Electrochemical behavior of gold dissolution with a novel eco-friendly synthetic gold lixiviant.

• Active NESGL dissolution of Au occurs at −300–600 mV where Q Au /Q T > 85.8 %. • Au dissolution declines at potential >600 mV due to much-enhanced NESGL oxidation. • No passivation on Au surface occurs achieving continuous NESGL leaching of Au. • pH of 11 appears to be optimal for NESGL leaching of Au. • NESGL leaching of Au is diffusion-controlled (E a = 6.9–7.7 kJ·mol−1 at 150–300 mV). Using environmentally friendly cyanide-free lixiviants to extract gold is of great significance with the rising requirement for environmental protection worldwide. A novel eco-friendly synthetic gold lixiviant (NESGL) that shows great potential to replace cyanide has been reported recently. In this paper, the electrochemical behavior of gold dissolution in the NESGL solution is investigated for the first time. Results suggest that gold occurs active dissolution in the potential of −300 to 600 mV where the coulombic efficiency of gold dissolution is >85.8 % but undergoes substantial reduction in oxidative dissolution at potentials higher than 600 mV due to the much-enhanced oxidation of NESGL. In contrast with cyanidation, no passivation on gold surface occurs in the NESGL solution achieving continuous leaching of gold with time. The change in pH significantly influences the NESGL dissolution of gold, and the optimal pH value appears to be 11. At the potential of 150–300 mV, the NESGL leaching of gold has an activation energy of 6.9–7.7 kJ·mol−1, indicating a diffusion-controlled leaching process. [ABSTRACT FROM AUTHOR]