Korean researchers developed a process to recover gold from waste with 99.9% efficiency, which is considered the best result achieved in the world so far.
In a paper published in the Chemical Engineering Journal, the scientists explain that they were able to achieve such a result by creating a capsule-type material in which a polymeric shell surrounds a multi-layered internal structure.
The developed material provides high recovery efficiency compared to conventional adsorption materials because it traps gold ions inside the capsule for recovery. The material also prevents clogging of the internal porous structure because the polymeric shell allows gold ions to penetrate while being impermeable to suspended solids present with gold.
According to the paper, by introducing functional groups that react only with gold ions in the multi-layered internal structure, gold that has passed through the polymeric shell could be stably recovered even with the coexistence of 14 types of ions and three types of suspended solids.
The study also points out that this capsule-type material can be produced through a continuous process based on the solvent exchange method. In addition to this, it can be reused at least 10 times while maintaining its high efficiency and recovery rate.
“The material developed can be immediately applied to related industrial processes as they can be easily synthesized in large quantities,” lead researchers Jae Woo Choi and Kyung-Won Jung said in a media statement.
“The results of this research are expected to serve as a basis for the development of the first eco-friendly process in Korea that can selectively recover and refine metal resources from waste and precious metal scraps generated in various industries.”
Choi and Jung also mentioned that in South Korea, which relies on imports for 99.3% of metal resources, the per capita consumption of metal resources is the highest among the country members of the Organization for Economic Cooperation and Development, while the consumption of precious metals in various industries such as renewable energy, healthcare, and semiconductors continues to increase.
In their view, urban mining could become a key mechanism to obtain some of those sought-after metals.