It is important to note that An AEM was used in the laboratory experiment for the inhibition of proton (H + ) leakage and concentration into the catholyte tank. In theory, the inhibition of protons into the catholyte tank of the experimental electrowinning cell improves Au recovery efficiency, because an increase in proton concentration decreases the reduction potential for the Au-iodide ion (AuI2 -). Chemical analysis results of the sample solutions collected from the electrowinning cell's feed and catholyte tanks after 2, 4 and 6 hrs (Table ), show that there was no Au concentrated in the feed tank after 2 hrs. However, after 2 hrs, there was 0.498 ± 0.021 g of Au (~47 wt.% of initial Au) which was concentrated in the catholyte tank, thus indicating that Au recovery as a deposit on the cathode was incomplete. Similarly, it was observed that after 4 hrs, Au recovery was incomplete, since 0.174 ± 0.015 g of Au (~16.4 wt.% of initial Au) was found to be concentrated in the catholyte tank. However, after 6 hrs it was found that no Au was concentrated in the catholyte tank, thus indicating that Au recovery as a deposit on the cathode was complete after 6 hrs. Chemical analysis results of sample solutions also found that no BMs reported into the catholyte tank, thus confirming that Au was selectively transported through the Au-IEM and into the catholyte tank. However, it is important to note that the chemical analysis results of the Au-IEM found that 0.03 ± 0.004 g of Cu was adsorbed onto the Au-IEM after the laboratory experiment together with 0.051 ± 0.004 g of residual Au. However, this adsorbed Cu was not stripped and transported into the catholyte tank. Chemical analysis results of the 1.02 ± 0.006 g Au deposit obtained after the laboratory experiment showed that Au was the only metal, which was quantitatively detected in the deposit, constituting >99%. Hence, the total Au recovery yield observed was 95.50 %. The high Au recovery yield observed is comparable to, but slightly lower than the 98.75 % Au recovery yield observed by Meng et al. . The lower Au recovery yield observed can be attributed to the loss of approximately 4 % of Au to the Au-IEM through incomplete elution/ stripping (this was confirmed by the presence of residual Au on the Au-IEM). In this instance, Au loss could be reduced by increasing the temperature or pH of the electrolyte solution in the catholyte tank. However, an increase in temperature and/or pH may have resulted in the degradation of the Au-IEM, due to a loss of mechanical strength in response to temperature changes, or osmotic shock in response to changes in pH .