There are a lot of peanuts grown in Mexico. Needless to say, the processing of them results in a lot of discarded peanut shells, which are generally considered to be a worthless byproduct. That could be about to change, however. Led by biotech expert Raul Pineda Olmedo, a team from the National University of Mexico and the Research Center of Advanced Studies has developed an air-purifying filter that utilizes the shells.

More specifically, the biofilter actually relies on microorganisms such as Fusarium fungi and Brevibacterium bacteria, which typically grow in peanut shells. These microbes take toxic compounds such as those commonly found in solvents, and convert them to carbon dioxide and water.

It takes approximately 28 days for an effective amount of the organisms to colonize one of the filters.

A microscope image of a peanut shell

Additionally, the shells' hollow structure maximizes their surface area, allowing for more contact with the air. Like other filtration materials, they do also trap airborne particles such as those that make up dust and smoke.

So far, a kitchen range hood-like prototype has been created, although it is hoped that the technology could be applied to a wide variety of air filters. The university is working on commercializing the innovation.

Peanut shells, incidentally, may also find use in the making of natural dyes.

Source: Investigacion y Desarrollo (Spanish)