Activated charcoal is charcoal processed using heat or chemicals so that it is highly porous. The pores give the material extremely high surface area so it adsorbs contaminants and undesired chemicals. Activated charcoal is the same as activated carbon and the terms are used interchangeably.
What Is Activated Charcoal?
Activated charcoal is a gray or black substance, available as a powder, granules, bricks, or coatings. It starts as organic material, which is rich in the element carbon. Bulk source materials include coal, coconut husks, peat, bamboo, wood, pitch, coir, and paper mill waste. Heating in a low-oxygen environment produces charcoal, which is mostly carbon. Either heating or chemical treatment “activates” the charcoal. Heating can be pyrolysis at high temperatures in an argon or nitrogen atmosphere or oxidation in heated oxygen or steam. Chemical activators include acids, strong bases, or salts. The resulting substance has numerous microscopic pores.
The way activated charcoal works is that liquids or gases pass into its structure and interact with the exposed carbon. Some contaminants becomes physically trapped within the pores. Others are adsorbed onto the carbon surface because they are attracted to the element. Eventually, the active sites on the carbon become filled. So, activated charcoal filters become less effective over time. Some filters are rechargeable, while others require replacement.
Difference Between Charcoal and Activated Charcoal
Charcoal and activated charcoal are related, but they aren’t the same thing. Charcoal is black carbon residue from heating wood or other organic material in a low oxygen environment. This removes volatile components and water. Charcoal does have a high surface area, but it is not nearly as effective as activated charcoal at capturing impurities. Activated charcoal is charcoal treated to increase its porosity.
Activated Charcoal Uses and Benefits
There are many industrial, agricultural, and medical uses of activated charcoal.
- In medicine, it absorbs poisons and overdoes from ingestion. It is ineffective against ethanol, methanol, cyanide, iron, lithium, petroleum products, ethylene glycol, strong acids, or strong bases.
- It is an over the counter treatment for gas and flatulence, diarrhea, indigestion, and skin infections.
- Activated charcoal powder is a popular deodorant.
- Some toothpastes and skin treatments use it as an abrasive, whitener, and for lifting away impurities.
- Activated charcoal may or may not be effective at minimizing hangovers. While it does not remove alcohol, it may collect impurities (congeners) that worsen a hangover.
- In water and air purification, activated charcoal filters volatile organic compounds and pollutants. It also traps chlorine, chloramine, tannins, phenol, volatile odor-producing compounds, and mercury compounds. It does not remove ammonia, nitrates, nitrites, fluoride, sodium, heavy metals, hydrocarbons, or pathogens.
- For the same reason, it is effective in spill cleanup and environmental remediation.
- In analytical chemistry, it finds use in extraction and purification.
- In agriculture, is is a pesticide, disinfectant, feed additive, and processing aid.
- Foods do not naturally contain activated charcoal. However, it is an additive that imparts a smoky flavor and black color.
Activated Charcoal Health Risks
Activated charcoal is on the WHO’s list of essential medicines, so it offers several benefits. Yet, its use also carries some risks, so you may wonder whether activated charcoal is safe.
- Potential side effects of activated charcoal use include black tongue, black stools, vomiting, and either diarrhea or constipation. Gastrointestinal blockage can occur.
- Combining activated charcoal with drugs used for constipation (magnesium citrate or sorbitol) may lead to electrolyte imbalances.
- Activated charcoal reduces or prevents the absorption of several drugs, including acetaminophen, digoxin, theophylline, tricyclic antidepressants, and birth control pills.
- It may reduce absorption of supplements.
- It also reduces absorption of certain nutrients.
- Because it is highly abrasive, brushing teeth using activated charcoal may damage tooth enamel.
- Inhaling dust from activated charcoal causes potentially fatal lung damage.
- Depending on the source material used in charcoal production, it may contain contaminants.
- In aquarium filtration, using activated charcoal adds iron to water over time, increasing plant growth and algae overgrowth. Water changes help reduce metal accumulation.
- Bradley, R.H.; Sutherland, I.; Sheng, E. (1996). “Carbon Surface: Area, Porosity, Chemistry, and Energy”. Journal of Colloid and Interface Science. 179 (2): 561–569. doi:10.1006/jcis.1996.0250
- Derlet, Robert W.; Albertson, Timothy E. (1986). “Activated Charcoal – Past, Present and Future”. West J Med. 145(4): 493-496. PMC1306980.
- Elliott C.G.; Colby, T.V.; et al. (1989). “Charcoal Lung. Bronchiolitis Obliterans After Aspiration of Activated Charcoal”. Chest. 96 (3): 672–4. doi:10.1378/chest.96.3.672
- Nicholson, Rebecca; Ferrier, Morwenna (June 28, 2017). “It’s in smoothies, toothpaste and pizza – is charcoal the new black?“. The Guardian.
- World Health Organization (2019). World Health Organization Model List of Essential Medicines: 21st List 2019. Geneva: World Health Organization. hdl:10665/325771.