If you’ve ever wanted to know what is an activated carbon filter, then this post is for you.

Below, we’ll go over every aspect of this filtering material, including what does an activated carbon filter do, how long does activated carbon filter last, what type of pollutants can it remove, as well as the advantages and disadvantages of activated carbon air filters.

This article will explain everything you need to know about activated carbon filters so you know what they can and can’t do for you.

What is an Activated Carbon Filter?

What is activated carbon filter

An activated carbon filter is a filtration method that removes gases, chemical vapors, and odor molecules. Activated carbon filters are used in air purifiers to adsorb pollutants like volatile organic compounds (VOCs) and smoke so you can enjoy fresh and clean air.

Activated carbon filters are made up of small bits of carbon that have been processed to be extremely porous. In fact, activated carbon is so permeable that 1 gram of this substance can have a total surface area of 500 m2 (5,400 sq. ft.) or more.

According to DESOTEC, an activated carbon manufacturer, “Activated carbon can be manufactured from a wide variety of raw materials such as coal, coconut, and wood. The production processes of activated carbon may be divided into chemical and thermal processes, both at elevated temperatures.”

  • Chemical activation is achieved by degradation or dehydration of the raw material structure (mostly wood-based).
  • Steam activation uses the basic principle of carbonization and oxidation followed by an activation step with steam. This process can be used to activate almost all raw materials (coal-based, coconut shell-based, wood-based, etc.)

After carbon has been activated, it can adsorb atoms, ions, and molecules from a gas, liquid, or dissolved solid that passes through the material.

And because activated carbon is so useful in air purification, all of the top 10 air purifiers include it.

See all of Amazon's Best Selling Air Purifiers

Is Activated Carbon the Same as Activated Charcoal?

Activated carbon is the same as activated charcoal. Both of these terms can be used interchangeably. Activated charcoal is simply a charcoal-based form of activated carbon.

People often wonder, do air purifiers help with smells or if activated charcoal bags reduce odors? And the answer is yes when a substrate like activated charcoal is being used.

How Do Activated Carbon Filters Work?

Activated carbon air filter

Activated carbon filters work by adsorption, which is a chemical reaction that causes pollutants to be trapped inside the pore structure of a carbon substrate. Activated carbon is used in air filters to collect gases, chemical vapors, and odor molecules from the air.

The process of air purification with an activated carbon filter works like this:

  • Contaminated air enters into the filtration system.
  • The air passes through the activated carbon air filter.
  • The process of adsorption takes place to remove the contaminants.
  • Purified air flows out of the activated carbon filter and back into the room.

As mentioned, activated carbon filters use ad-sorption, not ab-sorption, to remove pollutants from the air. The difference between those two terms is that during adsorption the contaminants stick to the outside of the carbon substrate. Whereas with absorption, contaminants are absorbed inside the structure itself, like a sponge.

You can think of it like this: adsorption is best used for air filtration while absorption is better for liquids.

Now, if an activated carbon filter is used on an air purifier in combination with a HEPA filter, then the activated carbon air filter can also work as a pre-filter. A pre-filter works as the first line of defense in air filtration by trapping large solid particles like dust, hair, and dirt. When used as a pre-filter, the activated carbon air filter will enable the HEPA filter to be more efficient at capturing microscopic pollutants and help it to last longer.

If you’re in the market for an air purifier, you may want to consider reading our guide on what to look for in an air purifier for more guidance.

What Does Activated Carbon Filter Remove?

An activated carbon filter can remove odors, gases, chemical vapors, and volatile organic compounds (VOCs) by trapping the molecules inside the substrate. By removing these substances, activated carbon filters can prevent pollutants from circulating in the air.

And according to research, “Activated carbon filters can be very effective at ozone removal, although not indefinitely because chemical reactions of ozone and carbon change the carbon.” But this pilot study “evaluated the ozone removal performance of moderate-cost particle filters containing activated carbon when installed in a commercial building heating, ventilating, and air conditioning (HVAC) system.” Researches found that “The filter banks with
prefilters containing activated carbon were removing 60% to 70% of the ozone 67 and 81 days after filter installation.”

How Long Does Activated Carbon Filter Last?

An activated carbon filter lasts between three to six months based on standard carbon manufacturers. The total length of time that activated carbon filters last depends on the amount of carbon used in the substrate. Thicker filters with more pounds of carbon last longer than thinner filters with less weight.

For example, on our page with the best air purifier for smokers, we recommend two products: Levoit LV-PUR131 and Austin Air HealthMate 400. The Levoit LV-PUR131 has a half-inch thick activated carbon air filter that lasts six months before a replacement is needed. The Austin Air HealthMate 400 has an activated carbon filter that spans 780 cubic inches and weighs 15 pounds for a total life expectancy of 5 years.

Are Activated Carbon Filters Safe?

Activated carbon filters are safe in every way. An activated carbon filter is used for medical, environmental, cosmetic, residential, and agricultural applications. An activated carbon filter is safely used for water purification, air purification, gas purification, and life support systems.

What are Activated Carbon Filters Used for?

  • Medical Applications: Activated carbon is used in medical applications to treat overdoses and poisoning as well as alleviate problems like indigestion and diarrhea.
  • Analytical Chemistry Applications: Activated carbon is often used to purify solutions of organic molecules and chemicals.
  • Agricultural Applications: Activated carbon is used in agricultural applications as an additive to animal feed, a natural pesticide, a processing aid, and a disinfectant.
  • Environmental Applications: Activated carbon serves a wide range of environmental uses like groundwater remediation and spill cleanup.
  • Cosmetic Applications: Activated carbon is used in cosmetic applications to remove toxins and contaminants. It’s a commonly found ingredient in shampoos, toothpaste, and face masks.
  • Water Purification: Activated carbon is a powerful substance for water purification. It can remove impurities from large-scale community-wide water systems as well as small-scale residential applications.
  • Air Purification: Activated carbon is used in air filters to remove pollutants like gases, chemical vapors, volatile organic compounds (VOCs), and odors from circulating in the air. An air purifier is a common filter found on air purifiers and can be added to HVAC systems.
  • Mercury Removal: When activated carbon is infused with halogens or sulfur, it can trap mercury gas and remove it from the air.
  • Life Support Systems: Activated carbon is used in the life support systems of spacesuits. The activated carbon air filter removes trace contaminants from the flow of oxygen to the astronaut as well as body odors.

Types of Activated Carbon

Activated carbon
  • Granular Activated Carbon (GAC): This consists of large pieces of activated carbon but has a smaller external surface area than other types of activated carbon.
  • Powdered Activated Carbon (PAC): This is made up of ground or crushed carbon that looks like a powder form.
  • Extruded Activated Carbon (EAC): This is fused with PAC using a binding agent to produce a cylindrical or spherical piece of carbon.
  • Bead Activated Carbon (BAC): BAC is formed from petroleum pitch and is similar to EAC.
  • Impregnated Carbon: This contains several types of inorganic impregnated compounds such as silver and iodine that are finely distributed on the internal surface of the carbon.
  • Woven Carbon: This is activated carbon that is woven into fibers to create a cloth material.
  • Polymer Activated Carbon: This is activated carbon that is coated with a biocompatible polymer. This gives the finished carbon a smooth, permeable outer shell that doesn’t block its pores.

Advantages of Activated Carbon Filters

  • Removes gases.
  • Traps chemical vapors.
  • Reduces volatile organic compounds (VOCs). (See our guide on the best chemical air purifier.)
  • Improves the quality of life for people with Multiple Chemical Sensitivity.
  • Reduces household odors from smoke, cleaning chemicals, pets, and garbage.
  • Reduces diaper pail odors. (See our guide on the best baby air purifier.)
  • Reduces smell from mold spores.
  • Freshens the air.
  • Low-cost air filter.
  • Lasts for three to six months (minimum).

If you want to learn more about the advantages of activated carbon filters and other air purification technologies, then check out our article on what are the benefits of an air purifier.

Disadvantages of Activated Carbon Filters

  • Does not trap allergens.
  • Does not remove bacteria or viruses.
  • Does not reduce pet dander.
  • Does not trap fine particulate matter.
  • Size and thickness determine the effectiveness.

Because of these limitations, we always recommend that you combine an activated carbon filter with a HEPA filter on an air purifier. The activated carbon air filter will remove the contaminants that a HEPA filter cannot trap and vice versa.

Activated Carbon Filter Summary

We hope you enjoyed this guide that answered the question, “What is an activated carbon filter?”

As you discovered, filtering material has been specially treated to make it more porous. And this transformation allows activated carbon to remove specific types of pollutants from the air.

In regards to what does an activated carbon filter do exactly, it removes gases, chemical vapors, and volatile organic compounds (VOCs) from indoor air so it’s healthier to breathe and smells fresher.

There are also many advantages and disadvantages of activated carbon air filters, and it’s best used in conjunction with another type of air filter called a HEPA filter. When combined in an air purifier, these two filters can remove most of the common airborne pollutants that are found indoors.

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About David Morrison

David is an Air Quality & Comfort Technician. He has expert knowledge on the technology and design of air purification, air conditioning, and heating systems. His main role is to write content that helps people get the most value out of their air purifiers, air conditioners, and heating units. (See Full Bio)