What Is Activated Carbon? Meaning, History and Classification for Water Treatment

Activated carbon is a carbonaceous adsorbent material with a highly porous structure, widely used in water purification, wastewater treatment, gas purification and many other fields. This article explains its meaning, historical development, adsorption principle, classification and handling precautions.

1. A Brief History

In 1794, a British sugar refinery used activated carbon to decolorize sugar syrup, marking the beginning of its industrial application. In 1959, a research institution of the American Petroleum Institute developed high-value products (such as desulfurizing agents), driving the further expansion of industrial applications.

2. The Adsorption Principle

Activated carbon adsorption refers to the use of the solid surface of activated carbon to adsorb one or more substances in water, so as to purify the water. The adsorption capacity of activated carbon is related to the size and structure of its pores. Generally speaking, the smaller the particles, the faster the pore diffusion, and the stronger the adsorption capacity of the activated carbon.

Adsorption by activated carbon is mainly physical adsorption, mostly in the form of monolayer molecular adsorption; the adsorbed amount as a function of the adsorbate concentration follows the Langmuir monolayer adsorption isotherm equation.

3. Classification

The Chinese national standard classifies activated carbon in two dimensions: one part is classified by the main raw material used in manufacture, and the other by a combination of the manufacturing raw material and the corresponding product shape.

Common product families include crushed synthetic-material granular activated carbon, synthetic-fabric activated carbon (carbon fiber cloth), felt-type synthetic activated carbon (carbon fiber felt), powdered coal-based activated carbon, carbon molecular sieves, honeycomb activated carbon bodies and water-purification filter cartridges/elements.

Across these product families, typical applications include: gas separation and purification, solvent recovery, flue gas purification, desulfurization and denitrification, water purification, wastewater treatment, catalyst supports, gas masks and military adsorption, gold extraction, food and beverage decolorization, monosodium glutamate purification, vinyl acetate synthesis catalysts, decolorization of injections and syrups for pharmaceutical use, blood purification, emergency treatment of water pollution incidents, waste incineration, chemical decolorization, air purification and odor removal, and integrated physical-chemical preparation technologies; special grades are also used as electrodes for supercapacitors.

4. Regeneration by Supercritical Fluid (SCF)

Supercritical fluids (SCF) have the advantages of high density, high solubility, high mass-transfer rate, good diffusion performance and low surface tension. The organic matter adsorbed on activated carbon dissolves very easily in SCF solvents. By changing the temperature and pressure, the organic matter can be effectively separated from the SCF, thereby regenerating the activated carbon.

5. Transport and Storage Precautions

During transportation, activated carbon must be handled with care: do not drag it with iron hooks, and keep it separate from hard objects. It should be loaded and unloaded gently, avoiding strong vibration, friction, trampling or throwing, so as to prevent the carbon granules from breaking, which would impair its performance.

Activated carbon should be stored in a cool, dry environment to avoid breakage of the inner and outer packaging, which would expose it to moisture and the adsorption of other substances in the air and degrade its effectiveness. It must never be stored together with toxic or harmful gases or volatile substances, and the storage location should be far away from pollution sources to ensure its safety.