The index of activated carbon represents an important criterion for the quality of activated carbon, that is, thefficiency of the adsorption capacity. The efficiency and capacity of activated carbon to adsorb the substances varies with the concentration in the air, relative humidity and temperature. The capacity index numbers are representative under average conditions and may vary under local conditions.
Mesh size refers to a measurement of the activated carbon granule. Such as 12*40mesh, 85% of the granules will fall through an 12 × 12 US wire mesh sieve and 95% will be retained on a 40 × 40 US wire mesh sieve placed below.
Molasses number is derived from the decolorization from molasses in solution, and refers to the measure of the content of mesopores (pores having diameters 2–50 nm) in the carbon granule after it has been activated compared to a standard carbon granule. The higher the number, the larger the molecule captured.
Iodine number is based on the amount of iodine adsorbed in testing, and is an indicator as to the porosity, or the content of micropores (pores having diameters ≤ 2 nm) in the carbon granule after it has been activated. The higher the number, the more activation in the carbon particle.
Ash is the measurement of oxides in the activated carbon granule expressed as a percentage. The lower the percentage, the higher the carbon portion of the granule and its activity.
CTC, that is Carbon Tetrachloride Activity (ASTM D3467), measures the loading of carbon tetrachloride, weight percent on carbon, at concentrations close to saturation in the air. The method is basically a measure of the pore volume of the activated carbon and is primarily used as a quality assurance test for the production of activated carbon.