Citrus peels could give activated charcoal a run for its money

Citrus peels could give activa...
Orange and grapefruit peels have been used to help purify polluted water
Orange and grapefruit peels have been used to help purify polluted water
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Orange and grapefruit peels have been used to help purify polluted water
Orange and grapefruit peels have been used to help purify polluted water
A diagram of the process
A diagram of the process

There may be a new way of keeping orange and grapefruit peels out of our landfills – besides composting them, that is. Researchers have devised a method of using the peels to remove heavy metals from wastewater.

The research was carried out by scientists at Spain's University of Granada, along with colleagues at Mexico's Center for Electrochemical Research and Technological Development, and Center of Engineering and Industrial Development.

First, the peels are desiccated using a vacuum drying treatment, after which they're subjected to a proprietary chemical treatment. As a result, their porosity and surface area increases. They're then granulated.

A diagram of the process
A diagram of the process

In lab tests, the treated peels were placed in columns (see diagram above) where they successfully adsorbed heavy metals such as copper from tainted water that was pumped through.

"The results show a great potential for the use of said materials as adsorbents capable of competing with commercial activated carbon for the adsorption and recovery of metals present in wastewater," says Romero Cano, a team member from the University of Granada. "It could be possible to carry out sustainable processes in which products with a great commercial value could be obtained from food industry residues."

A paper on the research was recently published in the journal Industrial Crops and Products. Scientists at Australia's Flinders University have also been removing heavy metals from water, using a polymer that incorporates a substance obtained from citrus peels.

Source: University of Granada

I thought activated carbon was widely used for absorbing organic molecules, heavy metals usually aren't in this class so, not surprising that something else (designed with these properties in mind) works better
very cool, because citrus is not well suited to composting. it does ok with vermiculture, but still not ideal.
Agreed with MD - activated charcoal is for organics, you would use an ion exchange resin - and there are many papers on using 'organic' base to make for example a Cellulose based ion exchange - so would really need to compare it to one of those. Activated carbon can absorb copper - but it is only a minor effect and I know I would not design a system with it for specifically removing copper
Ralf Biernacki
The peels are "subjected to a proprietary chemical treatment". Does that amount to carbonizing them, by any chance? ;-)
I prefer them in marmalade.