Soil bacterium recovers palladium from waste

Palladium is one of the platinum group metals (PGMs), which are among the most precious resources on earth. They are useful for a variety of applications due to their exceptional chemical properties. PGMs are routinely used in many catalytic systems and are the active elements of autocatalytic converters that reduce greenhouse gas emissions.

Dr Kevin Deplanche explains why new ways of recovering PGMs are needed: ’These metals are a finite resource and this is reflected in their high market value. Over the last 10 years, demand has consistently outstripped supply and so research into alternative ways of recovering palladium from secondary sources is paramount to ensuring future availability of this resource.’

Previous work in the team’s lab showed that Desulfovibrio desulfuricans was able to reduce palladium in industrial wastes into metallic nanoparticles with biocatalytic activity.

Now, the precise molecules involved in the reduction process have been identified. Hydrogenase enzymes located on the surface membrane of the bacterium carry out the reduction of palladium, which results in the accumulation of catalytic nanoparticles. The bacterial cells coated with palladium nanoparticles are known as ’BioPd’.