Activated Carbon Applications
Introduction
Ever since ancient times, activated carbon’s water purifying properties have been known. Today it is widely used in water, food production, aquariums and air treatment because of its unique properties and variety of applications. To activate carbon, i.e. create all the unique pores in it that give it a large surface area, it is normally treated with steam. Sometimes it is doped with certain chemicals like NaOH and Silver to add additional properties.
Forms of Activated Carbon
Activated carbon, normally made from different types of wood, coal or coconut shells, can be produced as a powder, granules, honeycomb form or pellets. Another form of activated carbon is made from pyrolysis of animal bones and these forms have the additional characteristics of removing Fluoride and Sulphates as they contain calcium.
Activated Carbon Various Forms: Powdered, Granules, Pellets
Honeycomb Activated Carbon
Properties In Water and Air
Powdered activated carbon (PAC) sinks in water because it is a solid, insoluble, particulate form of activated carbon with a density greater than water when wet. While it can be used to treat water by being added directly to it, the particles will settle to the bottom or be removed in a subsequent clarification/settling stage.
Active carbon hisses when added to water due to the rapid expulsion of air that is trapped in its highly porous structure, as the water is drawn into the pores by capillary action.
Powdered activated carbon can be explosive in air if it forms a combustible dust cloud under the right conditions, which include a strong ignition source, sufficient oxygen, and confinement. While not considered a high explosive, it is classified as a weakly explosive combustible dust that can cause a deflagration event (heating a substance until it burns away rapidly) if these conditions are met.
I have personally seen a powdered activated carbon dosing system that has blast controlled release hatches on its silo in case of a dust explosion.
Applications of Activated Carbon
Water Treatment
In Water Treatment, activated carbon has unique properties, It can:
- Remove chlorine
- Remove Ammonia
- Remove some heavy metals
- Remove PFAS
- Remove Colour, COD and TOC
- Pharmaceuticals
- Persistent Organic Pollutants
- Pesticides and insecticides
- Used as a material in Bio-filters that remove N and P
- Used in aquariums and fisheries water treatment to remove Ammonia and or biocides
- Fluoride and Sulphate removal using activated bone charcoal.
- Odour treatment
- In toothpaste
- In some soaps
- Used in Natural Biogas treatment to remove H2S, Siloxanes and CO2.
- Pre-Treatment for RO (BODAC)BODAC stands for Biological Oxygen-dosed Activated Carbon, a water treatment technology that uses activated carbon with pure oxygen to remove micropollutants. It is a bioprocess for creating ultrapure water by removing organic substances, nutrients, and various contaminants. A key benefit of this system is its efficiency in reducing chemical use, extending the lifespan of downstream equipment like reverse osmosis membranes, and decreasing operational costs.
Air Treatment
In Air treatment, it can be used to:
- Purify air treated by HVAC systems in buildings by removing unpleasant odours, CO2 and VOC’s
- Used in breathing safety equipment to remove toxic gases/VOC’s
- Used in flue gas treatment in EfW/incinerators to remove toxic gases, organics and mercury
- Used at Anaerobic Digester sites to remove H2S and CO2.
Activated carbon can remove CO2 from natural biogas, which is a crucial step in the biogas upgrading process. Activated carbon is an effective adsorbent for CO2 due to its high surface area, selectivity for CO2 over methane, and ability to be regenerated, though other methods may offer higher efficiency or different advantages.
Suez has a very interesting technology for N2O removal from sewage treatment works. They envelope the ASP basin with a “membrane” that consists of activated carbon doped with some proprietary catalysts that converts N2O to N2 and O2. It is called Acti-Layer:
Food Processing:
AC is used in purification by removing impurities, colour, odour, and taste from liquids and gases. Its applications include decolorizing and purifying sweeteners like brown sugar and syrups, purifying food-grade acids, and removing tannins and other impurities from wine and fruit juices.
Organic decaffeinated coffees are produced by extracting caffein from green coffee beans without the use of organic solvents. A water-based extractant solution is the preferred choice nowadays.
In Mining Operations
AC can remove heavy metals and is also used in gold mining recovery.
In Poison Control
Powdered Activated Carbon is used in emergency medicine to treat patients who have ingested poisons and/or overdosed on pharmaceuticals.
Mercury Abatement:
Sulfur or iodine-impregnated carbons are widely used to capture mercury emissions from industrial sources like coal-fired power stations and medical incinerators, preventing the release of this toxic heavy metal into the environment.
Radioactive Gas Retention:
In nuclear boiling water reactors, large charcoal beds are used to adsorb radioactive gases, allowing them to decay to non-radioactive solid species before the air is released.
Catalyst Support:
Metals like palladium or platinum are dispersed on the active carbon’s surface for use in hydrogenation and oxidation reactions, leveraging the massive surface area for increased reaction efficiency.
Specialized Purification in Pharma/Fine Chemicals:
High-purity, acid-washed activated carbons are essential for removing trace contaminants, colors, and odors from sensitive products like pharmaceutical intermediates, glycerin, and injectable solutions, where product purity is paramount.
Chemical Warfare Agent Protection:
In military and high-risk industrial environments, activated carbon cloth (such as the FLEXSORB® range) is used in advanced protective filters and masks against chemical, biological, radiological, and nuclear (CBRN) agents.
Chemical Characteristics of AC
The chemical characteristics of Activated Carbon is represented in so called adsorption isotherms in which the capacity of activated carbon to remove various chemical substances is quantified. There are also other parameters such as Iodine number which is the amount of Iodine that a gram of the AC can remove.
Activated Carbon Chemical Characteristics
Reactivation of Spent Activated Carbon
What makes Activated Carbon sustainable is that it can be re-activated after it has been spent and reused again. The process normally involves heat reactivation in kilns and sometimes steam is added to increase the number of pores/surface area.
Health and Safety
Inhaling activated carbon dust can be bad for the lungs, potentially causing irritation and, with prolonged, heavy exposure, benign pneumoconiosis (a lung disease from dust accumulation) with symptoms like coughing, wheezing, and shortness of breath, though it generally doesn’t cause severe lung scarring like silica dust. While usually not acutely toxic, respiratory protection is recommended in dusty environments, as used carbon might also carry absorbed toxins, and aspiration can be dangerous.
Powdered Activated Carbon silos need to have safety features engineered into them such as ATEX anti-spark design, blast proof enclosures and pressure release blast relief plates.
Suppliers of Activated Carbon
Below are some of the most prominent suppliers of Activated Carbon.
Desotec
Kemira
Chemviron
Calgon Carbon
Jacobi Group
Eurocarb
Donau Carbon
Various Chinese suppliers such as Shanghai Xing Chang Activated Carbon Co., Ltd. which is one of the largest in China for wood-based activated carbon, with an annual production capacity of 20,000 tons.
Suppliers of Mobile Activated Carbon Units
Chemviron, Desotec, Jacobi and NORIT supply mobile rentable activated carbon units which are practical and plug-and-play.
Mobile Activated Carbon Unit by Chemviron
CPL Mobile Activated Carbon Tank
Research On Activated Carbon Applications
Top universities and research centres actively exploring novel activated carbon applications include:
Clarkson University (USA): Researchers, notably Yang Yang, have recently developed a simple, chemical-free method to destroy “forever chemicals” (PFAS) adsorbed onto granular activated carbon using ball milling technology. This innovative approach addresses a major environmental challenge in water treatment.
Cornell University (USA): Researchers there synthesized an ultra-high surface area activated carbon with a BET area of (4800 m^2/g), one of the highest reported to date, which significantly advances the material’s potential for various applications.
University of Cambridge (UK): Academics here are involved in carbon capture, storage, and utilization (CCUS) research, exploring solutions like advanced solid adsorbents for post-combustion capture to reduce regeneration energies.
University of Nottingham (UK): This institution leads interdisciplinary engineering efforts in carbon solutions, including developing the next generation of activated carbon adsorbents for pre-combustion (CO2) capture. Key people involved in related projects include Colin Snape and Jihong Wang.
Chinese Academy of Sciences (China): This institution consistently ranks highly in overall research output and collaborates on advanced carbon material research, including on functionalized carbon adsorbents.
Market Share of Main Suppliers of Activated Carbon
Below is a Pie Chart Illustration of the main Activated Carbon suppliers in the US, EU and UK markets.
Pie Chart of Main Activated Carbon Suppliers
Conclusion
The applications of activated carbon are myriad and very important in industry and various water utilities. It’s use is projected to grow as more and more sewage treatment works upgrade their effluent treatment processes to remove persistent organic pollutants, insecticides, pharmaceuticals and PFAS.
References
https://www.nature.com/articles/s41598-022-25247-6
About the Author:
Rami Elias Kremesti is a UK chartered chemistry and water treatment specialist. He is passionate about protecting the environment and raising awareness about environmental pollution.
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