Carbon filters remove odors and organic chemicals (gaseous pollutants) through a process called adsorption. Carbon is often processed with heat to create more pores inside it increasing its adsorption capabilities.
Once a carbon filter becomes saturated with chemicals, it can no longer adsorb any more. Typically this happens without you even noticing it. This is why it is important to follow manufacturer guidelines and replace your filter regularly.
Activated carbon is an adsorbent material that can be used to remove certain chemicals from a solution. It is often used for the treatment of wastewater. It removes pollutants including pesticides, herbicides and ozone from water. It can also be used to remove organic odors and color contamination. Most of the time, the size and type of carbon needed depends on the contaminant. The carbon’s pore structure, molecular weight and polarity play an important role in the removal process. Activated carbon is generally made from raw organic materials such as coconut shell, coal or peat that have been treated through heat and activation processes.
Granular Activated Carbon (GAC) is used to treat industrial waste water from such industries as chemical factories, rubber thread factories and fabric dyeing plants. The GAC removes chemicals dissolved in the water such as aromatic compounds, hydrocarbons, detergents and chlorinated solvents. Most of the time, the carbon is reactivated on-site in a rotary kiln to be reused again.
Other large uses of activated carbon include removing volatile organic compounds such as Benzene, Toluene and Xylene from air. It can be used to remove odors from foods and beverages, purify drinking water and in cigarette filters.
Another way of using activated carbon is in the medical field. Activated carbon is used for poison treatment, odor control and in hospitals and doctor’s offices for blood purification during hemoperfusion.
Carbon is an unchallenged filter for chlorine and its disinfection byproducts, including trihalomethanes (THMs). Whole home carbon filters that use granular or block carbon can reduce these harmful contaminants to EPA maximum contaminant allowables. Carbon can also remove bad tastes and odors, VOCs, pesticides and organic chemicals. Solid or extruded carbon block filters work best for chlorination removal because they eliminate channeling of the water through pore spaces. In addition, they are more effective than traditional granular activated carbon (GAC) at removing the newer chloramine compounds.
When used in water filters, carbon works to trap contaminants at the surface of the carbon itself through a process called adsorption. A single pound of granular carbon has a massive amount of surface area with which it can attract chemical molecules. These molecules stick to the carbon, much like magnets stick to steel filings. As the molecule loses its charge, it releases itself from the carbon. The carbon keeps absorbing these molecules until it is full, and at that point it will need to be replaced.
Another use for carbon is short-term odor and VOC removal, such as during wildfires or during a remodel of your home. A carbon filter will quickly get rid of the smoke and VOCs that are released during these events. The carbon can then be disposed of in accordance with your local hazardous waste regulations.
Carbon filters are effective at reducing bad odors, especially those that come from cooking. They also reduce Volatile Organic Compounds (VOCs) that can be released from paint, thinning compounds, cleaning products and cigarette smoke. Exposure to VOCs can cause a range of health problems including nausea, headaches and cancer.
A carbon filter works to remove odors and VOCs by the process of adsorption. The pore structure of activated carbon allows water molecules to pass through but traps organic chemicals that are similar to them. The polarity of the chemicals causes them to bond or stick to the surface of the carbon. Chemicals with higher affinity for the carbon can displace those with lower affinity and they are released from the filter as they are adsorbsed.
Activated carbon can be produced from coal, wood, coconut shells and other materials. It is sold in granular form or as a solid block and can be used alone or in combination with other filtration systems such as reverse osmosis. A carbon block generally works better than GAC because the solid form prevents it from washing away during use.
Activated carbon can be used to filter both water and air. Some filters are certified to remove specific contaminants such as coliforms, cysts and iron or lead and arsenic. Look for the NSF label to find out what contaminants a particular carbon filter is certified to remove.
Fluoride is a mineral that exists naturally in our bones and teeth, plants, rocks, freshwater, seawater and many foods. It is also added to some municipal water supplies and can be found in dental products and supplements. Fluoride is widely known to help protect against tooth decay, but the risks of ingesting too much have become a source of controversy and concern.
A variety of methods are available for removing fluoride from drinking water, including adsorption, ion-exchange and reverse osmosis. Reverse osmosis filters use pressure to push unfiltered water through a semi-permeable membrane, allowing the water molecules to pass but trapping contaminants like fluoride. This method produces clean, contaminant-free drinking water that is healthier than bottled water.
Reverse osmosis systems can be used with a variety of carbon filter media types, including activated alumina, zeolites, bone char, and fluoride specific ion exchange resins. The system also uses a coagulation process to remove heavy metals (iron, lead, arsenic, and copper) as well as chlorine & chloramine, toxins & pesticides, pharmaceutical byproducts and petroleum byproducts. This method is a good fit for industrial wastewater with high levels of fluoride concentration and provides an alternative to calcium hydroxide precipitation and adsorption. However, this method is not suitable for low-level fluoride treatment due to long hydraulic retention times. Moreover, it requires large sedimentation and clarification tanks.