Banana skins stop metal ions from slipping away

A group of Brazilian researchers led by Renata Castro, have found that the classic comedy banana skin is actually very effective at removing heavy metal ions like copper and lead from water.

When you have heavy metals building up in water systems from run off of building works, industrial sites and factories, they can be harmful to wildlife, so we need to be able to remove them from the water. There are already several products used to do this, based on chemicals like activated carbon and silica - which is that stuff you get in those tiny white bags when you buy a handbag or a wallet. The silica based compounds are good because they have high surface reactivity and they can be reused several times. But they are expensive and use harmful solvents to make.

This isn't the first time that natural waste products have been investigated - things like sugar cane fibres and peanut shells have been used in the past, but compared to the standard metal extraction compounds, they're not very effective.

Castro and his team used minced banana peel and tested how well it extracted lead and copper ions that had been dissolved in water. They found that it was almost as effective at removing the ions as the currently used silica standard, and at least twice as effective as other natural products like sawdust. It was also able to be used up to 11 times without losing its ion-removing power.

So although this is just a study demonstrating that banana peels can be effective, it shows that there are natural products that can be effective, and so could be a good alternative in poorer areas, and with more research maybe even more widely.