Photo via SimonDavo
Biomass waste has a new use beyond cellulosic ethanol or electricity, thanks to Hidetaka Kawakita, a Japanese university professor who figured out a way to get trash such as paper and rotten fruit to reclaim precious metals from e-waste.
The technology has the potential to be a much cheaper way to such up metals such as gold, silver, platinum and palladium from fluid or melted electronic parts. Typical recovery methods for precious metals include using activated carbon or polymeric resin absorbent are not always effective and the better they are, the more expensive they are. They also are wasteful of water.
But this new biomass method uses natural properties in certain types of waste products to collect the metals.
Specifically, selected constituents are extracted from waste paper containing cellulose or lignin, or waste fruits, such as persimmon or lemon, containing a large amount of polyphenol. Then, those constituents are adjusted by an amination reaction. In this way, the new method can reduce the cost to 1/10-1/2 that of the existing methods.
One experiment using a fruit-derived absorbent had a recovery rate of 100% for gold. Imagine, rotten lemons recovering all the gold in e-waste. The different absorbents created from trash all had far higher recover rates that traditional recovery methods, in addition to having a lighter environmental footprint.
It will be exciting to see if these new methods are used on a wider scale in e-waste recycling plants. Maybe not to long from now, you’ll be asked to bring a few old lemons and some shredded paper along with your junked computer or old cell phone when you head to the nearest e-waste drop-off.