What is activated carbon filtration?
Discover the pros and cons of activated carbon filtration
Activated carbon filters are commonly used in air purification systems and water filters, due to their ability to target contaminants affecting tastes, odors, allergens and unpleasant pollutants.
Despite their relatively unimpressive small appearance, activated carbon filters are among the most effective filters on the market for removing contaminants. This short guide will take a closer look at activated carbon filters, including what they are, how they work, their benefits, and more.
What is an activated carbon filter?
An activated carbon filter is an extremely porous piece of solid carbon, usually in the form of a block of powder or granules. Activated carbon filters have a very large surface area – a single gram of this material has an average surface area of 500 square meters. This allows an activated carbon filter to adsorb (trap) many more contaminants than standard carbon filters.
Adsorption occurs when organic compounds present in water or air (depending on the use of the filter) undergo a chemical reaction with the carbon media and bind to the surface of the media. The higher the porosity of the activated carbon, the more impurities it can contain.
How do activated carbon filters work?
The activated carbon filtration process is simple. The filter is placed inside an air purifier or water filter, and when contaminated air or water passes through the filter, harmful contaminants are adsorbed into the media.
The result is that the water or air leaving the system is much cleaner because it has been stripped of contaminants that affect taste or odor, such as chlorine and gaseous pollutants. If used in combination with other filtration stages, activated carbon can protect these other filters from damage by large particles like dust.
Contaminants removed by activated carbon
From water, activated carbon filters can remove:
- Volatile Organic Compounds
- Hydrogen sulfide
In the air, activated carbon filters target:
- Volatile Organic Compounds
- Chemical vapors
The design of the activated carbon filter determines the contaminants the filter can remove and its effectiveness in removing those contaminants.
Uses of Activated Carbon Filters
The two most common uses of activated carbon filters are:
- In air purifiers: Activated carbon filters are used to remove odors and pollutants from the air, improving indoor air quality.
- In water filters: Activated carbon filters are also found in water filters, such as pitcher filters and under-sink filters, to improve the taste and quality of drinking water.
Large-scale uses of activated carbon filters include wastewater treatment, metal finishing, analytical chemistry, pharmaceutical processes, purification of distilled beverages, and groundwater remediation.
Benefits of Activated Carbon Filtration
Some of the biggest benefits of activated carbon filtration are:
- Natural Filter Media: Activated carbon is made from natural materials like coconut shell and wood, with no other substances or chemicals needed. This means that air or water can be filtered safely and naturally.
- EASY AND LOW COST MAINTENANCE: Activated carbon is one of the most affordable filtration materials and requires limited maintenance. When an activated carbon filter has reached its capacity, the filter simply needs to be replaced.
- Removes bad tastes and odors: No other affordable filtration technique is as effective as activated carbon in removing bad tastes and odors from air and drinking water.
- Attacks a range of impurities: In addition to taste and odor, activated carbon effectively filters out other organic chemicals, pollutants, gases and microorganisms, depending on its application.
Disadvantages of activated carbon filtration
Some of the setbacks of activated carbon filtration are:
- Cannot remove all contaminants: Activated carbon is very effective at removing a defined group of contaminants, but it cannot be used to completely purify air and water. Some chemicals and pollutants are not attracted to carbon media, which means other filtration techniques may be required.
- Short life: An activated carbon filter has maximum filtration capacity (the maximum amount of contaminants that can be trapped in the media until the media is eventually completely clogged). When this maximum capacity is reached, the filter stops working and must be replaced. The average life of an activated carbon filter is between 2 and 6 months, depending on the size of the filter and the contaminants in the air or water being treated.
- Requires long contact times: The longer the contact time between the filter and the air or water, the more efficient the filtration. This may mean waiting several minutes for filtration results.
- Can harbor bacteria: Activated carbon cannot be used to remove viruses and bacteria – and, in fact, this type of filter is known to harbor bacteria. Manufacturers can inhibit the growth of bacteria by adding trace materials like silver to the filter media.
Activated Carbon Filter Variables
Although all activated carbon filters can remove more impurities than standard carbon filters, not all activated carbon filters are designed to be exactly the same.
Different activated carbon filters contain different amounts of activated carbon and have different surface areas. The more activated carbon a filter contains and the larger its surface area, the more contaminants it can remove and the longer its life.
The pore size of the filter affects the adsorption rate. The smaller the pores, the faster the adsorption process. Some activated carbon filters are now infused with other materials, such as magnesium dioxide or copper oxide, to improve the filtration process.
Activated carbon filters are among the most effective tools for filtering air and water. Although activated carbon is not a purification technique, it is superior to other filters in removing impurities that affect taste and odor. Activated carbon has a number of uses, but AC filters are most often used in water filters and air purifiers.