Activated carbon is a type of carbon material that has undergone special treatment. It has an extremely large specific surface area (up to 500-1500 square meters per gram, equivalent to the area of a football field to multiple basketball courts) and a highly developed pore structure. These tiny pores are like a dense "molecular trap", capable of strongly adsorbing various substances.
Core feature: Strong physical adsorption capability. Its function mainly relies on van der Waals forces to fix impurity molecules or particles on its surface.
How is activated carbon produced?
The main production process consists of two steps:
Carbonization: By heating carbon-rich materials (such as coconut shells, wood chips, coal, nut shells, etc.) under high temperature and in an oxygen-deficient environment, volatile components are removed, resulting in the formation of the initial carbon structure.
Activation: Key step. At higher temperatures, react with carbon using steam, carbon dioxide, or chemicals (such as phosphoric acid). This process "burns off" substances like tar that clog the pores, expands the original pores, and creates a complex network of tiny pores, thereby achieving extremely high adsorption capacity.
The main forms of activated carbon
Granular activated carbon: Irregularly shaped particles, commonly used in water treatment filter tanks and air purification.
Powdered activated carbon: Extremely fine powder, with the fastest adsorption speed, is commonly used in emergency water treatment or industrial decolorization.
Activated carbon fiber: Made from fibers, it has more accessible pores and a faster adsorption/desorption rate. It is commonly used in gas purification and special protection.
Ceramic-like activated carbon: In a block-like structure, with low resistance, it is commonly used for treating large volume exhaust gases.
Main application fields
1. Water treatment (core application)
Drinking water purification: Remove residual chlorine, odors (such as earthy mold smell), organic pollutants, some heavy metals and disinfection by-products, and improve taste and color.
Wastewater treatment: Advanced treatment of difficult-to-degrade organic substances, pigments, and toxic substances in industrial wastewater or domestic sewage.
Household water purifier: It is one of the core filter materials for almost all household water purification devices (such as water filters, faucet filters, pre-filters for reverse osmosis).
Groundwater/soil remediation: Adsorbing volatile organic compounds and petroleum pollutants in groundwater.
2. Air Purification and Gas Treatment
Air Purifier: Adsorbs indoor pollutants such as formaldehyde, benzene, and VOCs, as well as odors and smoke.
Industrial waste gas treatment: Recovering organic solvents, removing odors and toxic gases.
Gas masks and respirators: As the crucial filtering layers, they ensure respiratory safety.
Fridge odor removal: Household activated carbon packs are used to absorb food odors.
3. Food and Pharmaceutical Industry
Food Industry: Used for decolorization, deodorization and purification of sugar solutions, edible oils, alcoholic beverages and beverages.
Pharmaceutical field: As an antidote (taken orally, used for treating poisoning caused by certain drugs or toxins), and in the purification process of pharmaceutical production.
4. Other fields
Gold extraction: Used for adsorbing gold from cyanide solutions.
Electronic industry: Used for solvent recovery and purification.
Energy storage: An electrode material used for supercapacitors.
The specific functions and limitations of activated carbon in water treatment Advantages:
Efficiently removes chlorine and chloramines (primary application: to protect the subsequent reverse osmosis membranes).
Effectively improve the taste, aroma and color.
Absorbs a portion of organic chemical substances (such as pesticides, endocrine disruptors).
The technology is mature and the application is flexible.
Limitations and Precautions:
Selective adsorption: It has poor adsorption effect on substances with strong polarity (such as most inorganic salts, hardness ions like calcium and magnesium, and heavy metal ions including lead and arsenic). It cannot soften the water quality, nor can it remove scale, nitrate, fluoride, or microorganisms (bacteria, viruses).
Adsorption saturation: The adsorption capacity of activated carbon is limited. Once it reaches saturation, it not only loses its effectiveness but may also become a breeding ground for microorganisms, leading to secondary pollution. It is necessary to replace it regularly (depending on water quality and usage, it is usually recommended to replace the household filter element every 6 to 12 months).
Non-renewable: Household-grade activated carbon cannot regain its performance through simple rinsing or exposure to sunlight; it requires professional high-temperature regeneration.
Summary
Activated carbon is an efficient and porous adsorption material, a leading product in physical purification. It is indispensable in ensuring drinking water safety, purifying air, industrial production, and medical emergency treatment. However, understanding its specialties (adsorbing organic substances, chlorine, and odors) and limitations (not mineralized, not softened, and prone to saturation) is crucial for the correct use and selection of appropriate water purification solutions. In water treatment systems, it is often combined with other technologies (such as reverse osmosis, ultraviolet disinfection, ion exchange) to achieve comprehensive purification.
