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Everything You Need to Know About Activated Carbon Air Filters

Everything You Need to Know About an Activated Carbon Air Filter

In 2021, the global air purifier market had a whopping $12.26 billion value. Between now and 2030, this market size will likely grow by 8%. This growth comes largely from growing health concerns in everyday environments post-pandemic. 

A decent part of this market size comes from activated carbon air and furnace filters. With an activated carbon air filter, you can remove everything from harmful gases to foul odors from the air in your home. 

But how do these air filters work? And should you be using them in your own home?

We’ve assembled this guide to clue you in on everything activated carbon-related, including how you can switch to the most high-quality air filters.

The Activated Carbon Production Process

Activated charcoal has a history that stretches back centuries. Its most popular use has historically been for the purification of water. But, it has also proven to be quite effective for air purification, as well. 

The discovery of activated carbon has quite a colorful history. Its extensive production process is a bit of a marvel in the natural world.

What is Carbon?

The terms charcoal and carbon are interchangeable. This is because they both refer to the substance that remains after incomplete combustion. 

For example, imagine the charred wooden remains after a campfire. These blackened pieces, which were not readily combustible during the actual fire, are mostly comprised of carbon. 

Carbon may also be industrially produced by heating a substance inside a vacuumed space. This releases all of the volatile compounds, while still leaving behind the carbon.

Charcoal is commonly made using substances such as:

  • Wood
  • Coconut shells
  • Coal

Any substance used in this production process will make a slightly different kind of carbon.

How Is Carbon Activated?

Fresh carbon is not considered “activated,” unless it has gone through some additional processing. This processing makes carbon much more effective at trapping gas molecules. 

To consider carbon “activated,” it must have an increased surface size. This happens when you inject certain substances into the carbon to create tiny pores throughout the surface.

Substances that are commonly used include:

  • Steam
  • Carbon dioxide
  • Hot air

The created pores serve as additional areas where the carbon can trap gases, making it more efficient for use as a filter.

Different Types of Activated Carbon and the Ideal Filtration System

There are a few different types of activated carbon out there. They each have their own specialized applications.

In order to design the proper carbon filtration system, you’ll need the right amount of contact time, the right vessel size, and an appropriate pressure drop. Material testing is also essential for determining the most suitable type for your needs. 

Some common activated carbon types you may come across include:

Granular Activated Carbon (GAC)

GACs have a smaller surface area than other types of activated carbon. This is because the actual particle size is much larger than other powered types of activated carbon. 

This carbon type has a place in both liquid and gas filtration. This is one type that you will commonly find in air filtration systems.

Powdered Activated Carbon (PAC)

PAC is actually just crushed up or ground carbon. It is a powdered form that can pass easily through a standard mesh sieve. 

Generally, most consider PAC too small to be effectively used in any kind of filtration system. Instead, it is commonly used to purify liquids by being directly added to the substance itself. This type is also sometimes used as an ingredient in cosmetic products. 

Extruded Activated Carbon (EAC)

Almost a mix of GAC and PAC, extruded carbon types are actually PAC that has undergone fusion to form into a cylindrical or spherical shape. This makes it easier to fit into certain filtration systems. 

This is one type that is not commonly found in actual air filter sheets. It is commonly found in actual air filtration system units, though.

Bead Activated Carbon (BAC)

Bead activated carbon is similar to EAC. The difference is that it uses petroleum pitch in its production process. The grain size is often much smaller, as well. 

Because it is often formed into a spherical shape, it is ideal for liquid applications. This type will be commonly found in-home water filtration systems, though it is not as popular for air filtration.

Impregnated Carbon

A porous carbon, substances such as silver and iodine are often added to impregnated carbon. Other substances are also sometimes used depending on the various application needs. 

This type is commonly used in specialty air filters, such as those in museums and galleries. It is sometimes used for the purification of drinking water, as well.

Woven Carbon

Woven carbon is quite special. It is the weaving of activated carbon into an actual cloth-like material. It has a variety of applications, many of them industrial.

One of its most useful applications, woven carbon is quite useful in the absorption of odors.

Polymer Activated Carbon

Polymer activated carbon is often used in medical settings. It is porous carbon that receives a biocompatible polymer coating along its surface. This provides the surface with a smooth appearance without covering the pores, which would render the carbon useless. 

Generally, you’ll find this type of carbon in hospitals to filter toxic substances out of a patient’s blood.

Activated Carbon Filters: A History

As far as researchers can tell, Egyptians were the first to use charcoal for medicinal purposes around 1500 BC. They used it to remove foul odors from wounds. 

By 400 BC, charcoal was being smeared on the inside of water barrels to improve its taste to sailors on long journies. They would also occasionally char the barrels themselves to keep the water fresh. 

The use of carbon continued during World War I. Here, soldiers used it inside of gas masks to filter out deadly gases, though it was only partially effective. 

After World War II, however, the production and use of activated carbon grew exponentially. The applied uses of activated carbon during the war went on to set the stage for its use in water and air purifiers.

The Safety of Activated Carbon Filters

Activated carbon air filters are extremely safe. Carbon filters, in general, have a variety of purposes, including:

  • Medical
  • Environmental
  • Cosmetic
  • Residential
  • Agricultural

Activated carbon filters are helpful for water purification, air purification, gas purification, and even some life support systems for astronauts. Let’s take a closer look at some of these uses. 

Medical Treatment

Activated carbon filters have served important medical uses for thousands of years, helping to save lives. It is mainly used to treat overdoses or poisonings by filtering toxins out of the body. 

Occasionally, activated carbon can even help to relieve problems such as excessive diarrhea and indigestion. 

Environmental Clean Up

Industrialization can have some difficult impacts on our environment. Luckily, activated carbon can help clean up some messes and remove pollutants from a variety of different sources. 

Some common uses for activated charcoal within the environment include spill clean-up and remediation of groundwater.

Cosmetic Use

Toxins and contaminants can have a negative effect on our appearance. So, more and more people have started using activated carbon to purify and remove them. 

In fact, activated carbon is a commonly found ingredient in a variety of different cosmetic products. These include shampoos, face masks, and toothpaste or other tooth whitening products.

Residential Use

You might have an activated carbon filter sitting in your kitchen right now. Activated carbon is commonly used in residential water filters to remove mineral build-up and soften water. 

Activated carbon water filters are also used in large-scale water treatment plants. So, both you and your larger community may be benefiting from their use. 

And, of course, you’ll find activated carbon in air filters and as a common addition to HVAC systems.

Agricultural Applications

Activated carbon has many purposes throughout the agricultural industry to fight harmful substances such as poison or pests. In fact, it is often found as an added ingredient to some animal feeds.

Additionally, activated carbon is a wonderful natural pesticide, disinfectant, or processing aid for many different steps of the food production process.

Other Common Uses

Beyond just these uses, activated carbon is also critical for many scientists and researchers. It is often used in analytical chemistry to purify organic molecules and chemical solutions. 

Activated carbon can also trap and remove mercury gas when paired with sulfur or halogens. Astronauts also sometimes use activated carbon air filters in their spacesuits to purify their flow of oxygen from harmful contaminants.

How Do Activated Carbon Air Filters Work?

Of all air filtration methods, activated carbon contains certain special properties. These help it to remove dangerous gases, foul odors, volatile organic compounds (VOCs), and other pollutants from the air. 

Activated carbon filters accomplish this more thoroughly than other filters, such as HEPA. This is because they are able to trap gas molecules inside a bed of carbon, also called activated charcoal. This makes it probably the best filter for odors and odor removal. 

Activated carbon, or charcoal, has become popular as a cleansing method in recent years. For air filtration specifically, activated carbon has been quite effective at removing dangerous gas particles and improving indoor air quality. Though it can’t remove all the things living in our air, it is still tremendously effective.

Gaseous Pollutants vs. Activated Carbon

Activated carbon utilizes a process known as adsorption to remove pollutants from the air.

This is different from absorption, where the substance you’re removing (like water) is absorbed into the structure of the object removing it (like a paper towel). The absorbed substance does not become part of the structure on a molecular level. Instead, it just fills the spaces inside. 

With adsorption, however, the pollutant will not go inside the structure. It will instead stick to the outside of the carbon. 

This works because of the lattice-like structure of carbon atoms that comprises a piece of carbon. When activated, this lattice becomes even larger and more complex, giving the pollutant more places to stick. As long as there is an open place adsorption site, the pollutant will affix itself to the carbon. 

The only issue with activated carbon is that adsorption sites will become full over time, meaning there will be no room for new pollutants.

Additionally, as conditions such as humidity and temperature change, certain pollutants may be re-released. This is because the carbon will attempt to catch other pollutants with a higher affinity for adsorption.

Because of this, your carbon filter may begin to release a strange odor. This is a good sign that it’s time for a replacement.

Using Your Activated Carbon Air Filter Effectively

Your home air purification system requires proper use in order to remain effective. An activated carbon filter can be great at removing pollutants, but only when used properly. Some tips you should follow include:

High Carbon Count

Some US-made air filters may say they have activated carbon filters, but only contain trace amounts of carbon. These will become saturated almost immediately, rendering them entirely ineffective. 

In general, a good activated carbon filter will utilize at least 5 pounds of carbon. Granted, different types of carbon have different efficiencies. Some carbons may have more points for saturation than others. 

However, generally, the more carbon used in production, the more effective the filter will be. This is because you need as many adsorption sites as possible for your filters to be effective and long-lasting.

Ample Dwell Time

Air needs time to pass through the carbon if you want an effective clean. The time air spends passing through the carbon filter is also called its “dwell time.” 

To achieve plenty of dwell time, it is vital that you have continuous airflow and a thick layer of carbon. With just a thin layer of carbon, the air will go in and out without much purification. A thick layer will allow the air the appropriate time for full cleansing.

Clean Filters Work Best

It is vital that you change your filter regularly. If your carbon filter is completely saturated, it is useless against air pollutants. However, it can be difficult to tell when carbon has become fully saturated, as there are no set guidelines. 

A strange odor is your first line of defense. But, your filter won’t always start to smell when it’s saturated. 

Your filter manufacturer likely provides guidelines of their own, though these are only rough estimates. Carbon saturation will vary depending on how heavily the filters are used and how many pollutants are in the air. For example, if you live in a place where wildfires are common, you’ll likely need to replace your filters much more often. 

In general, a monthly replacement schedule should be effective for most air pollutants. 

It is important to note that activated carbon filters, even clean ones, cannot remove carbon monoxide. You should always have a carbon monoxide detector in your home to prevent exposure and poisoning.

Activated Carbon Uses and Effectiveness

Activated carbon filters can be used as furnace filters, air filters, or even as an air conditioner filter. However you are using them, though, they are most effective against a few common substances.

These substances include:

Foul Odors

Most mechanical air filters do not at all remove foul odors. This is because they only filter particles, they do not absorb them. Many people choose activated carbon filters because of their superior ability to fight off bad smells.

Activated carbon filters are especially useful for those with pets or young children, who can contribute to odors around the home. Though activated carbon filters cannot remove all smells, they are the most effective type for odor removal. 

Volatile Organic Compounds (VOCs)

VOCs are compounds that feature low water solubility and high vapor pressure. These are generally man-made chemicals, such as those found in paints, refrigerants, and medications. They are also located in cigarette smoke and certain cleaning chemicals. 

Some common VOCs include:

  • Xylene
  • Benzene
  • Toluene
  • Chlorinated compounds

Regular mechanical filters, such as HEPA, are largely ineffective against VOCs. However, carbon filters are quite efficient at removing these harmful gaseous substances. 

Activated Carbon Filter Drawbacks

Unfortunately, despite the benefits of carbon filters, they are not perfect. There are a few drawbacks you should be aware of before switching to a carbon-based AC filter, furnace filter, or air filter. 

These include:

Replacing Filters

Carbon filter replacement can become an inconvenient hassle. Additionally, replacing your saturated US-made furnace filters or air filters can become quite expensive. 

There’s also the trouble of knowing when to replace your filters, as there are no visual cues to do so. You’ll either have to trust the recommendations of your manufacturer or guess on your own, which could lead to some ineffectiveness down the line.

Ineffective Against Particle Pollution

While activated carbon filters are great at removing gaseous pollution, they aren’t quite as effective against particle pollution. This can include substances such as:

  • Pollen
  • Dust
  • Certain particles in smoke

This can become a bit dangerous if you live in a home where someone smokes, or in an environment where wildfires are common. You should speak to a trusted professional to determine if activated charcoal filters are right for you. All of the activated carbon furnace filters through Filters2Go, have clear MERV ratings so you know the minimum level of filtration.

Cleaning Filters

Unfortunately, you cannot clean carbon filters at home. Once they are fully saturated, they will remain that way.

You would have to re-activate the charcoal which is an expensive and complicated process. Generally, re-activating carbon requires the resources found only in a factory setting. 

This means that replacement is the only option. Some may claim that you can simply vacuum your filter or clean it with water. However, this will only remove dust, leaving behind odor particles and dangerous VODs.

Making the Most of Carbon Air Filters

Carbon air filters are relatively effective on their own. However, because of their limitations, they are best used in conjunction with HEPA filters in critical environments. 

HEPA stands for “high-efficiency particulate air.” This type of filer is up to 99.97% effective at clearing the pollutants that carbon filters cannot. This includes dust, pollen, molds, and bacteria. 

Like carbon filters, HEPA filters require regular cleaning to remain appropriately efficient and continue functioning properly. 

When used together, HEPA filters and activated carbon filters can drastically improve indoor air quality. Most of the things that travel and live within the air are effectively captured with either one of these two filters, making a conjunction system appropriate even in the more polluted environments.

How Much Do Activated Carbon Air Filters Cost?

Because of their specialized uses, activated carbon air filters are a bit more expensive than their traditional counterparts. Usually, they’ll cost anywhere from $20 – $40 per filter. However, there are special coupons and discounts you can use to save. 

Activated carbon filters can be used in a whole house filtration system, or in more specialty units. Carbon filters are also often found in air purifiers and air purification systems. 

Generally, however, when carbon filters are used in air purification systems, they must also use another filter, such as a HEPA filter. Many air purification systems actually have a 3-filter system. This starts with a traditional fiberglass air filter, then a carbon filter, and finally a HEPA filter to effectively clear the air of all contaminant types. 

It is good practice to budget specifically for clean air costs. The fact is, the inside air can be up to 5 times as dirty as outdoor air. When it becomes trapped inside, it can start to impact your health.

Breathe Easy With Carbon Air Filters

Now that you know more about the popular activated carbon air filter, you can more readily determine if a carbon system is right for you. There are plenty of ways to customize your air filtration system to work most appropriately for you and your family and still fit within your budget. 

Find the right filter for you using our online catalog. With hundreds of options to explore, you’re sure to find the perfect system to help your family breathe a little easier. 

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