Both have an iodine value of 800, but their effects differ by half: the untold secrets of activated

Activated carbon is ubiquitous in industrial fields such as water treatment, air purification, and food decolorization. Iodine value, as a core indicator of its adsorption performance, is often used as a standard by purchasing personnel. When two test reports both prominently display an iodine value of 800, many people subconsciously assume their purification effects should be comparable. However, in practical applications, a harsh reality is that even with the same iodine value of 800, the effectiveness can differ by as much as half.

    1.What does an iodine value of 800 actually mean?

First, we must clarify the definition of iodine value. It refers to the amount of iodine (mg/g) that activated carbon can adsorb under specific conditions, primarily reflecting the degree of development of its internal micropores (pore size <2nm). For adsorbing small molecules (such as residual chlorine and small organic molecules), iodine value is a fairly effective reference indicatorHowever, the problem is that the pollutants that actually need to be adsorbed are far more than just iodine molecules.

    2. The Invisible "Pore Volume" and "Pore Size Distribution"

The adsorption capacity of activated carbon depends on its large internal pore structure. In addition to micropores, there are also mesopores (2-50 nm) and macropores (>50 nm).

a. Micropore size

Carbon A with an iodine value of 800 may have very well-developed micropores, but for adsorbing humic acid, lignin, or certain large molecular weight pigments, these micropores have too small an "entrance," and large molecular pollutants simply cannot enter, thus greatly reducing the adsorption effect.

Carbon B, with an iodine value of 800, although having the same iodine value, has a more rational pore structure and an appropriate proportion of mesopores. For the same complex water bodies, it can accommodate and adsorb more large molecular pollutants, thus performing better.

b. Methylene Blue Value

If the iodine value is an indicator of the ability to handle "small parcels," then the methylene blue value is an indicator of the ability to handle "large parcels." A complete activated carbon test report should consider all these values.

    3. Material composition: coal, wood, and coconut shell

The raw materials of activated carbon (coal, fruit shells, wood, coconut shells) fundamentally determine the "genes" of its pore structure.

• Coconut shell charcoal: It is usually hard and has extremely well-developed micropores, making it very suitable for gas phase adsorption (such as air purification and solvent recovery) and adsorption of small molecules.

• Wood charcoal: It often has well-developed mesopores and macropores, which gives it a unique advantage in liquid phase decolorization (such as sugar decolorization and chemical refining).

• Coal-based charcoal: Its performance is between the two, its price is relatively moderate, and it has a wide range of applications.

If the medium-porous requirements of water treatment are met, applying the microporous advantages of coconut shell charcoal will yield vastly different results, even if the iodine value is the same at 800.

Iodine value is a beacon, but not the entire continent. True experts in charcoal selection understand how to discern the underlying pore structure, raw material composition, and physicochemical properties beyond a single numerical value. The most suitable is the most efficient.

· Fujian Guangyuan Carbon Products Co.,Ltd.