Coal-based activated carbon is developed through a series of processes including carbonization, cooling, activation, and washing. It typically appears as black cylindrical activated carbon, amorphous coal particle activated carbon, also known as granulated carbon. Coal-based activated carbon can also be extruded with powdered activated carbon and binder. It boasts features such as well-developed pore structure, excellent adsorption properties, high mechanical strength, easy recyclability, and low cost; it is used in toxic gas purification, waste gas treatment, industrial and domestic water purification, solvent recovery, etc.
Coal-based activated carbon boasts unique advantages such as high strength, well-developed pores, large specific surface area, and especially large micropore volume. It has a strong adsorption capacity for various organic substances in water, free chlorine, and harmful gases in the air. It is an excellent adsorbent for deep purification of urban drinking water, used to remove bacteria and toxic gases from the air.
Coal-based activated carbon features a well-developed pore structure, excellent chemical stability, and mechanical strength, making it an excellent broad-spectrum adsorbent material. It is primarily categorized into granular activated carbon and powdered activated carbon based on appearance, with granular activated carbon further divided into shaped coal-based carbon and raw coal crushed activated carbon. According to its application, it can be used for water purification, air purification, decolorization, solvent recovery, injection, and protection, among others. Due to its resistance to acid, alkali, and heat, granular activated carbon is easily regenerable after adsorption saturation, making it an indispensable adsorbent material in modern industrial production and environmental protection.
Coal-based activated carbon adsorption of solute molecules in water is a complex process, resulting from the combined effects of various forces such as ionic attraction, van der Waals forces, and chemical mixing forces. According to the dual-rate diffusion theory of adsorption, it is believed that adsorption is a dual-rate process consisting of two stages: rapid and slow diffusion. Rapid diffusion refers to the process where solute molecules diffuse uniformly within the large-pore carbon particles along the radial direction, encountering minimal resistance. These large pores generate radial diffusion resistance. When molecules further diffuse from the large pores to the micro-pores connected to them, a significant resistance is encountered due to the narrow pore diameter, resulting in a very slow speed. Micro-pores are also uniformly distributed within the carbon particles but do not contribute to radial diffusion resistance.
Factors affecting the adsorption of coal-based activated carbon involve the polarity, molecular weight, and spatial structure of solute molecules, which depend on the characteristics of the water quality. Coal-based activated carbon exhibits selective adsorption for different molecular substances.
