How Activated Carbon Purifies Indoor Air Spaces
Activated carbon, also known as activated charcoal, is a powerful material used to purify the air in homes, offices, and industrial environments. Its remarkable ability to trap gaseous pollutants makes it an essential component in modern air purification systems. Understanding how activated carbon purifies indoor air spaces reveals the science behind its effectiveness and its critical role in maintaining healthier indoor environments.
This post will explore the detailed mechanics of this process, from the production of activated carbon to its specific applications in removing common indoor air pollutants. We will examine how factors such as pore size, temperature, and humidity influence its performance. Additionally, we will cover the various forms of activated carbon filters and how they are integrated into air purifiers and HVAC systems to deliver clean, fresh air.
What Are the Sources of Indoor Air Pollutants?
Pollutants originating from various sources within our living and working spaces can compromise indoor air quality. Certain solids or liquids emit these pollutants—known as volatile organic compounds (VOCs)—as gases. Common sources of VOCs include:
- Paints, varnishes, and solvents
- Building materials and furnishings
- Cleaning supplies and disinfectants
- Air fresheners and personal care products
- Office equipment such as printers and copiers
- Tobacco smoke
These pollutants can lead to a range of health issues, from minor irritation to more severe long-term conditions.
How Is Activated Carbon Produced?
Carbonaceous source materials such as coconut shells, wood, or coal produce activated carbon. The manufacturing process involves two main stages. First, in a process called carbonization, the raw material is heated to high temperatures in an environment without oxygen. This step removes impurities and creates a carbon-rich char. Second, this char undergoes activation. This is typically done by exposing it to steam or carbon dioxide at even higher temperatures, which erodes the internal structure of the char. This creates a vast network of microscopic pores and significantly increases its surface area.
What Is the Mechanism of Adsorption?
Adsorption is the process of gas or liquid molecules binding to the surface of a solid. In the case of activated carbon, the large internal surface area created by its porous structure provides an ideal environment for this to occur. Gaseous pollutants from the air pass through the carbon filter and become trapped on the inner surfaces. The expansive surface provides countless bonding sites for gaseous pollutants, effectively removing them from the air we breathe.
How Does Surface Area Affect Adsorption?
The effectiveness of activated carbon is directly proportional to its surface area. A larger surface area means more available sites for pollutant molecules to adhere to. The activation process is designed to maximize this surface area. The intricate network of pores of varying sizes allows the carbon to adsorb pollutants with different molecular sizes and weights, making it a versatile purification medium.
How Does Pore Structure Influence Adsorption?
Activated carbon’s pore structure is critical to its performance. Micropores, the smallest pores, are particularly effective at trapping small pollutant molecules. Larger pores, called mesopores and macropores, serve as pathways that allow pollutant gases to travel deeper into the carbon structure, ensuring the entire volume of the material is utilized. The distribution of these pore sizes can be tailored during the manufacturing process to target specific types of pollutants.
What Pollutants Does Activated Carbon Remove?
Activated carbon is highly effective at removing gaseous pollutants and odors from the air. This includes a wide spectrum of VOCs, such as formaldehyde, benzene, H2S, and toluene, which are common in indoor environments. It also excels at eliminating odors from cooking, pets, and smoke.
However, standard activated carbon filters do not remove particulate matter such as dust, pollen, or mold spores. For this reason, they’re often used in conjunction with particulate filters such as HEPA filters.
How Do Temperature and Humidity Affect Performance?
Temperature and humidity significantly influence the efficiency of activated carbon filters. Adsorption is generally more effective at lower temperatures because pollutant molecules have less kinetic energy and are more easily captured. High humidity can reduce the capacity of some filters, as water molecules can compete with pollutant molecules for adsorption sites on the carbon surface. The effectiveness of some activated carbon filters may diminish in environments with high humidity.
You might be thinking that carbon wouldn’t be a good tool for odor removal in the wastewater industry. However, Simple Solutions carries Norit Darco’s H2S LP, a carbon specifically designed to remove H2S from a highly saturated airstream. Darco H2S LP converts any H2S from moist airstreams into elemental sulfur through a catalytic process. This sulfur is retained in the activated carbon’s pore structure. Darco H2S LP is very hydrophilic, so it works well in environments with wide ranges of relative humidity. It’s most effective in gas streams with relative humidities of 60 to 100 percent (saturated).
What Are the Different Forms of Activated Carbon?
Activated carbon is used in air purification systems in several forms. Granular activated carbon (GAC) consists of small pellets and is often used in filter beds. Powdered activated carbon (PAC) has a smaller particle size and can be applied to surfaces or used in slurries.
Pelletized activated carbon is another option. The benefit of pelletized carbon include a reduction in back-pressure; plus, it’s less likely to clump up (carbon caking). There are specific impregnated activated carbons for specific VOCs; for example, activated carbon impregnated with caustic soda is used for H2S removal. Impregnated carbons work through chemical reaction. The downside is that this chemical reaction generates heat, increasing the chances of a bed fire.
Carbon-impregnated fabrics are another common form, in which carbon is bonded to a fibrous substrate. Each form offers different airflow characteristics and efficiencies, allowing for customization based on the specific application.
How Are Carbon Filters Used in Air Purifiers?
In standalone air purifiers, activated carbon filters are typically paired with other types of filters to provide comprehensive air cleaning. A common configuration includes a prefilter to capture large particles such as dust and hair, a HEPA filter to remove fine particulate matter, and an activated carbon filter to adsorb gases and odors. This multistage approach ensures that particulate as well as gaseous pollutants are effectively removed from the air. An activated charcoal odor absorber is particularly useful in this context for eliminating persistent smells.
A Cleaner Indoor Atmosphere
The use of activated carbon is a scientifically proven method for improving indoor air quality by removing a wide range of gaseous pollutants and odors. Its highly porous structure and immense surface area make it an exceptionally adsorbent material.
By understanding the factors that influence its performance and the various ways it can be implemented, consumers and facility managers can make informed decisions to create healthier indoor environments. Whether through standalone air purifiers or integrated HVAC solutions, activated carbon plays a vital role in providing cleaner, fresher air.
Simple Solutions Distributing's extensive selection of activated charcoal odor absorbers is perfect for air purification in homes, offices, industrial facilities and more. Explore our collection today.