Jun 29, 2020 16:00:00

A polymer that can efficiently recover gold and platinum from dust such as circuit boards will be developed

With the progress of digitalization, a new polymer has been developed that can easily extract precious metals such as gold from

electronic waste, which is increasing in the world.

Precious metal recovery from electronic waste by a porous porphyrin polymer | PNAS
https://www.pnas.org/content/early/2020/06/17/2000606117

Using a porous porphyrin to reclaim precious metals from electronic waste
https://phys.org/news/2020-06-porous-porphyrin-reclaim-precious-metals.html

New polymer easily captures gold extracted from e-waste | Ars Technica
https://arstechnica.com/science/2020/06/new-polymer-easily-captures-gold-extracted-from-e-waste/

Electronic waste, as its name suggests, is waste generated from electrical and electronic products. Electronic waste continues to grow as the digital industry develops, with around 50 million tonnes being discarded annually worldwide. Not only are harmful substances such as lead, cadmium, and mercury contained in many of such electronic wastes creating environmental problems, but also valuable and reusable substances such as rare earths contained in metal waste remain unrecycled. Abandoned

The world's expanding “e-waste” crisis calls for measures by the United Nations, etc. 1 photo International News: AFPBB News
https://www.afpbb.com/articles/-/3208106

The slow progress in recycling e-waste is due to the inefficient recycling process itself. Under such circumstances, a research team led by Mr. Yeongran Hong of the Korea Institute of Science and Technology has developed a new porous polymer 'COP-180' that can easily extract precious metals such as gold from electronic waste. COP-180 is made from an organic compound called porphyrin . The research team used the property of porphyrin to form a complex with a metal atom, and formed a large number of very small holes in COP-180 to adsorb the metal atom.

The research team is also conducting an experiment to collect precious metals such as gold with COP-180. First, put the circuit board in an acidic solvent and mix for several days to peel off the metal atoms you want to take out. When COP-180 is put into this solution, the porphyrin micropores in COP-180 adsorb metal atoms and precipitate as a mass. When acid is applied to this mass, COP-180 and metal atoms are separated, so only metal atoms can be taken out. In the experiment, platinum and gold were particularly efficient at collecting, and 94% of the gold contained in the circuit board could be recovered.

In addition, in the experiment, it was confirmed that about 1.62 grams of gold can be adsorbed per 1 gram of COP-180. Converting these results, COP-180 worth 5 dollars (about 500 yen) can collect gold equivalent to 64 dollars (about 6900 yen). In addition, COP-180 can be reused even after taking out metal atoms with acid, so the research team explains that 'the cost of a series of recovery work is considerably cheap'.

The research team pointed out that the printed circuit board contains more precious metals than the ore of the mine, but 80% is sent to the landfill as it is because there is no recovery method. He said that streamlining the processing of e-waste can help prevent economic opportunities.