How Carbon Adsorption Works
Absorption is something we all probably understand pretty well, but adsorption just looks like a typo. When we at AirClean Systems explain how our proprietary gas-phase coconut shell activated carbon filters are excellent adsorbents, many people don’t understand what that means, how it works, or why they should care. It’s essential to understand what adsorption is so that we can also understand how it dictates which company’s carbon filters will serve your needs best and keep you safe from the hazardous chemicals you are trying to avoid inhaling.
Absorption vs. Adsorption
We all feel pretty confident we know what absorption is, but getting a deeper understanding of the term will be helpful. Absorption is defined as “When one substance enters the volume or bulk of another substance.” Absorption is when a substance (typically a liquid) penetrates into another substance (usually a solid). A simple example of this is when someone dunks a doughnut into their coffee. The coffee is absorbed into the doughnut, penetrating the outer surface and reaching the innermost portions.
Now for the one we’re all scratching our heads about. According to the Encyclopedia of Ecology, adsorption is “a surface process that leads to the transfer of a molecule from a fluid bulk to a solid surface.” So basically, adsorption is when a particle sticks to the surface of a solid substance without entering it and is held there by inter-molecular forces. A really easy way to think of what this looks like is a chocolate covered pretzel. The chocolate adheres to the surface of the pretzel, getting into every nook and cranny, but doesn’t get inside the actual pretzel. The chocolate just clings to the pretzel’s exterior, leaving the pretzel itself crisp and crunchy.
How does carbon adsorb?
Carbon is a nonmetallic element found naturally all around the world and is simple to make from most organic substances. The carbon used in AirClean Systems’ carbon filters is made from coconut shells. Before use in a filter, the carbon must be activated. In order to activate carbon, it must be super-heated with steam or chemicals, which “creates a dense network of microscopic pores that can vary in type, each presenting differing adsorption characteristics.”
These pores are the key to what makes carbon such an excellent adsorbent. Each speck of carbon is riddled with these microscopic pores, which can trap molecules that happen to be passing through. By utilizing activated carbon in an air filter, air that is full of potentially hazardous fumes will be purged of all these impurities, allowing only clean air to pass through.
This may seem a little too simple to some. Pass air filled with dangerous fumes through some carbon in a filter and, just like that, it’s safe to breathe? Surprisingly, using carbon to purify air is incredibly effective. According to the Activated Carbon Producers Association, in nearly all cases, “impurities can be removed to below the detection limit, meaning that the most stringent air quality regulations can be complied with. The activated carbon technology is reliable, simple, and has been proven over many years.”
Why does it matter?
Once carbon has been used in a filter to adsorb hazardous chemicals from the air, it becomes impregnated with all those chemicals. The more effective the carbon is at adsorbing chemicals, the better it is at keeping your air clean and yourself safe. However, this makes the carbon within filters potentially very hazardous, especially after it has been used to purify air from dangerous chemicals.
Some carbon filters employ granular carbon to adsorb chemicals, but these pose a significant danger. Granular carbon filters are notorious for releasing carbon dust. If the filter has been used to trap hazardous substances, then it is likely that the released carbon dust fragments are impregnated with those substances. Now, contaminated dust is coating any surfaces it falls on within your lab or workspace. This makes traditional granular carbon filters a risky choice when dealing with harmful chemicals.
AirClean Systems recognized this flaw and engineered a solution: a proprietary bonding process that holds the carbon in a predictable matrix. This matrix prevents the carbon from shifting and being pushed out into the ambient air, keeping any contaminated carbon contained and your lab safe. This is why it is important to fully grasp what adsorption is because it can affect your lab and your health. Be sure your lab employs the best and the safest carbon filters when working with potentially hazardous substances.