Activated carbon specific surface area analyzer - Database & Sql Blog Articles

Activated carbon, also known as a carbon molecular sieve, is a black porous solid made from carbon. It typically has a specific surface area ranging between 500 to 1700 m²/g and exhibits strong adsorption properties. This makes it one of the most widely used industrial adsorbents. Its high porosity and large surface area allow it to trap various pollutants within its internal structure. The greater the surface area and the more developed the pore system, the stronger the adsorption capacity.

Key characteristics of activated carbon include:

Adsorption Properties

Activated carbon consists of fine carbon particles with a large surface area and tiny pores—capillaries—that provide strong adsorption capabilities. These capillaries are capable of capturing gases or impurities due to their extensive surface area. When such gases come into contact with the capillaries, they are adsorbed, leading to purification. The surface area of activated carbon is crucial for its performance. The BET (Brunauer–Emmett–Teller) method is the standard technique used to measure the specific surface area of activated carbon. In China, the national standard GB/T 19587-2004 outlines this procedure. The JW-DA specific surface area analyzer is an advanced instrument that accurately performs BET analysis, offering both direct contrast and automated testing. It is the only fully automated and intelligent surface area detection equipment in China, with high stability and accuracy. This device has been exported to countries like Japan and the United States, featuring user-friendly software designed in collaboration with Japanese engineers.

Adsorption Capacity for Different Gases (unit: ml/cm³):

Hâ‚‚, Oâ‚‚, Nâ‚‚, Clâ‚‚, COâ‚‚

4.5, 35, 11, 494, 97

Catalytic Properties

Activated carbon often acts as a catalyst during adsorption processes, demonstrating catalytic activity. For example, when sulfur dioxide is adsorbed, it can be catalytically oxidized to sulfur trioxide. The presence of oxygen-containing functional groups on the surface of activated carbon allows it to participate in various chemical reactions, such as the formation of phosgene from chlorine gas and carbon monoxide. When activated carbon is combined with metal salts, such as palladium, it can significantly enhance catalytic efficiency. Even without other catalysts, it can catalyze reactions like olefin oxidation with high speed and selectivity.

Due to its well-developed pore structure, large internal surface area, and good resistance to heat, acid, and alkali, activated carbon is commonly used as a support material for catalysts. In organic chemistry, it serves as an excellent carrier for platinum and palladium catalysts in reactions such as hydrogenation, dehydrocyclization, and isomerization.

Mechanical Properties

(1) Particle size: Determined using a standard sieve method, which measures the weight of activated carbon retained on and passing through each sieve to indicate its distribution.

(2) Bulk density: Refers to the weight of activated carbon per unit volume, including both the pore space and interparticle voids.

(3) Particle density: Measures the weight of activated carbon per unit volume, excluding the intergranular voids but including the pore volume.

(4) Strength: Reflects the carbon’s ability to resist crushing.

(5) Abrasion resistance: Indicates how well it resists wear and friction.

These mechanical properties directly impact the application of activated carbon. For instance, bulk density affects container size, particle size influences filtration, and the distribution of particle sizes impacts fluid resistance and pressure drop. The strength and abrasion resistance determine the service life and regeneration potential of the activated carbon.

Chemical Properties

In addition to physical adsorption, activated carbon also engages in chemical adsorption. Its adsorption behavior depends on both the pore structure and the chemical composition of the surface. Activated carbon not only contains carbon but also small amounts of oxygen and hydrogen-containing functional groups, such as carbonyls, carboxyls, phenols, lactones, terpenes, and ethers. Some of these surface compounds originate from the raw materials, while others form during activation via air or steam. Surface sulfides and chlorides may also appear. During the activation process, minerals in the raw material concentrate into ash, primarily composed of alkali metal and alkaline earth metal salts like carbonates and phosphates, which can be removed by washing or acid treatment.