The bacterium that eats heavy metal and poops gold is a tiny badass.
This is real news that went viral a few years back. The metaphor may sound bizarre, but its role in the extraction of precious metals is phenomenal. This particular bacterium can grow on waste it ingests, detoxify it, and excrete (or remove) it from its system in the form of pure metals, such as gold.
The bacteria I am talking about are Cupriavidus metallidurans, a bacterium that consumes toxic metals as if they were a snack. Thanks to its ability to extract pure metals from waste, this particular bacterium has fascinated metallurgists and environmentalists alike. To check out the interesting chemistry behind the phenomenon, check out this article.
Why is this gold pooping bacteria back in the spotlight?
Originally, this research article was published in 2018. However, almost 7 years later, this viral bacterium is making the headlines yet again. This time, helping scientists extract platinum and palladium from car wastes, truly a “best from waste” approach.
Platinum from Spent Automotive Catalysts (SAC)
For car lovers out there, you would know that catalytic converters are devices found in the car’s exhaust systems. They convert harmful gases like CO, NO, and other hydrocarbons into less harmful gases. They contain a ceramic or metallic core coated with platinum-like materials. Over time, they get deactivated and are called SAC.
These SACs may sound like waste, but are valued at rates more than gold!
Here’s why. It is due to their platinum content- rare and expensive and traditionally recovered through harsh techniques employing chemicals and high temperatures. They are not just energy-intensive but also affect the environment.
That’s where our viral bacterium comes into play
SACs are crushed and leached using mild acids to release the platinum and palladium ions. The bacteria are added to this solution. It slowly ingests the platinum and palladium ions and enzymatically reduces them. This causes the metals to precipitate as nanoparticles either inside the cell or extracellularly. Extracellular nanoparticles are easier to purify as downstream processing is easy.
Benefits of using bacteria to extract metals
- It is cost-effective
- Ecofriendly
- Produces nanoparticles that we can directly use in industries
The numbers speak for themselves.
Nearly 62% of platinum and 52% of palladium were recovered using this method.
In a world racing towards sustainable mining and getting the best out of waste, recovering precious metals from e-waste is a huge deal.
Let’s continue to make the best out of waste so we can increase the economic value of the waste.
Happy reading!
Fascinating, thanks for sharing.