Enhancement of gold-cyanide biosorption by L-cysteine

摘要

The presence of L-cysteine increased gold-cyanide bios-on by protonated Bacillus subtilis, Penicillium chrysogenum and Sargassum fluitans biomass at pH 2 by (148 approx 250) percent. The respective Au uptake by these biomass types was 20.5 #mu#mol/g ,14.2 #mu#mol/g and 4.7 #mu#mol/g of Au. Au-loaded biomass can be eluted with 0.1M NaOH. The elution efficiencies exceeded 90 percent at pH 5.0 with the Solid-to-Liquid ratio S/L = 4. Biosorption of anionic AuCN_2~- complex involved ionizable protonated cysteine-loaded biomass functional groups. An adverse effect of increasing solution ionic strength (NaNO_3) was explained by a triple layer surface complexation mechanism. The NO_3~- anion competed with AuCN_2~-.Results confirmed that certain waste microbial biomaterials are capable of effectively removing and concentrating gold from solutions containing residual cyanide.