Recovery of zero-valent gold from cyanide solution by a combined method of biosorption and incineration

A new combined way of biosorption and incineration is presented for the recovery of gold from gold–cyanide solutions. Decarboxylated biosorbent (DCB) was prepared by removing interfering carboxyl groups from the surface of inactive Corynebacterium glutamicum. The recovery of gold from the exhausted biosorbents was performed using elution or incineration. The maximum gold(I) uptakes were obtained as 50.19 and 86.16 mg/g for the raw biomass and DCB, respectively. The biosorption performance of DCB indicated that interfering carboxyl groups were successfully removed. The recovery efficiency of ionic gold through elution and purity of metallic gold by means of incineration were over 93% and as high as 61.89%, respectively. The result of XPS analysis indicated that the gold(I) was able to be reduced into zero-valent gold during incineration. It was noted that the combined method of biosorption and incineration could be effective for concentration and recovery of gold from the cyanide solutions.