The product known as amorphous carbon is usually in the form of black powder, granules or pellets, and is primarily composed of carbon with minor amounts of hydrogen, oxygen, sulfur, nitrogen, and chlorine. Its porous structure allows for a high surface area, making it a useful material in various applications.
Activated carbon also possesses a graphite-like fine structure, but with smaller grains and a less orderly arrangement between its layers. It exhibits a significantly large surface area, ranging from 500 to 1000 m2/g, which contributes to its strong adsorption capabilities. This material can effectively adsorb gases, liquids, and colloidal solids onto its surface. When it comes to gases and liquids, the amount of adsorbed material can be comparable to the mass of the activated carbon itself.
Moreover, the adsorption of substances by activated carbon is selective, with non-polar substances being more readily adsorbed than polar ones. Additionally, among substances of the same series, those with higher boiling points are more easily adsorbed. Increased pressure, lower temperature, and higher concentration also result in higher adsorption quantities. Conversely, reducing pressure and warming facilitate the desorption of gases.
Activated carbon finds common applications in gas adsorption, separation, and purification processes. It is also utilized for solvent recovery, decolorizing sugar liquids, refining oil and glycerin, and as a deodorizer in drinking water and refrigerators. In gas masks, activated carbon serves as an effective filtering agent. Furthermore, it can act as a carrier for catalysts or metal salt catalysts.
The production of activated carbon primarily relies on raw materials such as wood, hard nut shells, or animal bones. There are two main methods for producing activated carbon. The first involves activation using steam, carbon dioxide, flue gas, or other agents at temperatures between 800 and 900 °C. The second method is chemical activation, which can be achieved through processes like the phosphoric acid method or the zinc chloride method. These chemical activation methods facilitate the creation of activated carbon with well-developed pores by utilizing activators that promote both activation and pore formation.
