The Extraction Of Gold From Plants And Its Application To Phytomining

Abstract

Phytomining is the use of hyperaccumulating plants to extract a metal from soil with recovery of the metal from the biomass to return an economic profit. This work looks at the possible methods for recovering gold from plant material, including chemical reduction with and without solvent extraction, thermal reduction and copper electrodeposition. Some progress was made with ascorbic acid as the chemical reductant. A solid phase was produced at the liquid-liquid interface after solvent extraction. The deposition reaction reduced the gold concentration in methyl isobutyl ketone (MIBK) to less than 2 ppm, equating to 85% recovery, in 3.5 hours. Copper electrodeposition also gave some promising results. However, both require much more work before they are viable for scale-up.