What is the significance of the Iodine number in activated carbon? Is higher always better?

When purchasing activated carbon, Iodine Number is one of the most frequently mentioned parameters, with common levels such as 500, 800, 1,000 mg/g or higher. However, Iodine only reflects a partial characteristic of the material. To select the appropriate carbon, businesses need to simultaneously consider the type of substance to be adsorbed, particle size, CTC, hardness, ash content, and actual operating conditions.

What is Iodine Number?

The Iodine Number, typically measured in mg/g, indicates the amount of iodine that a unit mass of activated carbon can adsorb under specified test conditions. It also serves as a reference indicator for the development level of the micropore system and the adsorption capacity for small-sized molecules. For example, carbon with an Iodine Number of 1,000 mg/g, in principle, has a greater capacity to adsorb iodine than a type with 600 mg/g under the same test conditions.

Why a high Iodine Number may not always be more suitable?

A high Iodine Number does not mean that the product will always perform more effectively in every system. Each application has different substances to be removed and different treatment conditions: water may contain color, odor, residual chlorine, or organic compounds; gas treatment may involve solvent vapors, odors, or certain volatile organic compounds; in food and chemicals, decolorization or impurity removal may be required.

Adsorption capacity depends on the compatibility between molecular size and pore structure. Therefore, even two products with the same Iodine Number can yield different efficiencies if their pore structure, raw material, or physical properties differ.

Actual Operating Conditions

Adsorption efficiency also depends on the concentration of the substance to be treated, water/gas flow rate, contact time, temperature, humidity, pH, carbon bed height, flow velocity, and competing substances in the environment. For instance, if the flow rate is too high and the contact time is too short, even carbon with a high Iodine Number will struggle to fully utilize its adsorption capacity. Therefore, one should not solely choose carbon with the highest Iodine Number. A product with a moderate Iodine Number but with appropriate particle size, good hardness, ash content meeting requirements, and a pore structure suitable for the substance to be treated can still provide better operational efficiency.

Parameters to Consider When Selecting

• CTC
• Kích thước hạt (Particle Size)
• Độ cứng (Hardness)
• Độ tro (Ash Content)
• Cấu trúc lỗ xốp (Pore Structure)
• Surface Area
• Moisture Content
• Actual Operating Conditions

Particularly, for GAC used in filter columns, hardness affects the ability to limit attrition, dust generation, and material loss. Low ash content is often a concern in high-purity applications, but the appropriate level still depends on the specific process.

Coconut Shell Activated Carbon Grades from MEISEI INTERNATIONAL TRADING

MEISEI INTERNATIONAL TRADING supplies granular activated carbon (GAC) and powdered activated carbon (PAC) for various water treatment, gas treatment, odor removal, and industrial applications. GAC grades have Iodine Numbers ranging from 500–1,400 mg/g, with particle sizes of 4×8, 6×12, 8×20, 8×30, and 12×40 mesh; PAC has Iodine Numbers ranging from 500–1,200 mg/g, with particle sizes of 200–325 mesh. Grade selection is made based on the actual requirements of each application.

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