Abstract:
Microalga, possessing high binding affinity to different metals, has been considered as a promising biosorbent.
Precious metals recovery and adsorbent regeneration are important for the financial competitiveness of
biosorption with other processes. In this study, the desorbing agent thiourea was studied at different
concentrations, contact time, pH and temperatures to optimize gold elution from the self-flocculating
microalgae Scenedesmus obliquus AS-6-1. The variation in desorption performance with the adsorption time
was also investigated. The gold-loaded biomass of S. obliquus AS-6-1 was regenerated efficiently by 0.2 M of
thiourea at 25 ℃ and pH of 1.0 within 15 minutes. The adsorption time had significant effect on subsequent
desorption, with a decrease in desorption efficiency with an increase in adsorption time. S. obliquus AS-6-1 as
biosorbent remained efficient biosorption and desorption potential for gold(III) recovery in the first two
adsorption/desorption cycles. The microalga cells could be harvested/separated from solutions by their gravity
sedimentation. However, more studies are still required to enhance the regeneration of S. obliquus AS-6-1 by
improving its flocculating property.
