Understanding CTC Value in Activated Carbon

The CTC value is a widely used specification in the activated carbon industry, particularly for products intended for gas-phase and vapor-phase applications. It provides a standardized measure of a carbon’s ability to adsorb organic vapors and is an important indicator of overall pore volume.

What CTC Value Measures

CTC stands for carbon tetrachloride activity. The test measures the percentage of carbon tetrachloride by weight that a sample of activated carbon can adsorb under standardized conditions. A higher CTC value indicates greater total pore volume and, generally, a stronger capacity for adsorbing organic vapors. Typical CTC values for commercial activated carbons range from 40 percent to over 100 percent, depending on the raw material and activation process used.

How CTC Relates to Performance

While the CTC value is a useful screening tool, it primarily reflects total pore volume rather than the distribution of pore sizes. Two carbons with similar CTC values may perform differently in a specific application if their pore size distributions differ. For applications targeting small molecules, micropore volume is more relevant. For larger molecules, mesopore and macropore volumes matter more. CTC value should therefore be considered alongside other specifications such as iodine number, surface area, and application-specific isotherm data.

When CTC Value Matters Most

CTC value is especially relevant for solvent recovery, fuel vapor canisters, gas masks, and industrial emission control systems. For liquid-phase applications like water treatment, iodine number and methylene blue value are generally more informative indicators of expected performance.