Find a polymer that can extract gold and platinum from an electronic circuit board

Electronic waste, as its name implies, is a waste made from electrical and electronic products. As the digital industry grows, electronic waste also continues to grow, with about 50 million tons being phased out annually worldwide.

Not only harmful substances such as lead, cadmium and mercury in many electronic waste will cause environmental problems, but also valuable and reusable substances such as rare earths have not yet been recycled. .

This is a difficult task because the recycling process is inherently inefficient, due to the long classification process, health risks and environmental impacts. Most electronic waste also gathers in landfills and countless other chemicals.

Under such circumstances, a team led by Yeongran Hong of the Korean Academy of Science and Technology developed a porous polymer called COP-180. It is capable of easily extracting precious metals like gold from electronic waste with cheap, clean and efficient technology.

COP-180 is made from an organic compound called porphyrin, which consists of circular ring molecules that tend to bind to transition metals, including precious metals. The team noted that the structure of the polymer allows it to remain stable when immersed in acid solution. This is important because acid solutions are used to remove metal from the electronic circuit board. And its high porosity allows it to absorb large amounts of precious metal.

Polymer testing has shown it to be effective in absorbing platinum and unexpectedly highly effective in absorbing gold.

First, place the board in acid solvent and stir for a few days to peel off the metal atoms that you want to remove. When COP-180 is added to this solution, the micropores porphyrin in the metal atoms adsorbs COP-180 and precipitates in bulk. COP-180 and the metal atoms are separated, so only metal atoms like gold or platinum remain.

In the experiment, 94% of the gold contained in the circuit board could be recovered. More specifically, 64 USD worth of gold is recovered with only 1g of absorbent material, worth 5 USD. And researchers note that the absorber can also be reused, making it even more economically valuable.

Currently, about 80% of printed circuit boards containing many precious metals are still thrown into landfills because there is no recovery method. And this new research will streamline the disposal of e-waste, thereby creating new economic opportunities in the future.

The report was published in the scientific journal Proceedings of the National Academy of Sciences (Proceedings of the US National Academy of Sciences).

See Gigazine