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Coffee has the ability to absorb toxic fumes
Last reviewed: 01.07.2025
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The first cup of coffee in the morning - what could be more wonderful! But did you know that the grounds left over from ground coffee in the coffee maker can also be very useful? If handled correctly, they can eliminate one of the worst smells in the world - the smell of sewer fumes.
The process of making a carbon filter that can trap hydrogen sulfide. The structure of the caffeine molecule is shown in the center. (Illustration: City University of New York.)
While searching for environmentally friendly substances capable of absorbing toxic fumes, scientists from the City University of New York (USA) have discovered that a material obtained by deep thermolysis of coffee grounds can absorb hydrogen sulfide, a toxin that gives sewer fumes their wonderful aroma.
Typically, the production of carbon adsorbents for air purification from hydrogen sulfide (acid) requires the treatment of the carbon mass with nitrogen bases, such as ammonia or melamine (to incorporate active "basic" nitrogen). In any case, such a procedure is not very environmentally friendly and sharply increases the price of the final product.
At the same time, the remains of coffee seeds are already "charged" with a nitrogen-rich substance - caffeine. Under conditions of thermolysis of organic matter, it is caffeine that gives the resulting carbon structure the ability to remove sulfur gases from the air.
The process of making a carbon filter from ground coffee residue looks like this: coffee grounds are mixed with water and a small amount of zinc chloride (a chemical activator) and heated to 800 ˚C. This forms a carbon mass consisting of carbon particles with pores from 10 to 30 Å in diameter, full of active nitrogen and perfectly suitable for capturing nearby hydrogen sulfide molecules.
That's it, you can drink coffee and put the coffee grounds to use: recycling waste and producing a filter for cleaning toxins in one bottle. Elegant and cheap.