<P> Iodine number is defined as the milligrams of iodine adsorbed by one gram of carbon when the iodine concentration in the residual filtrate is 0.02 normal . Basically, iodine number is a measure of the iodine adsorbed in the pores and, as such, is an indication of the pore volume available in the activated carbon of interest . Typically, water - treatment carbons have iodine numbers ranging from 600 to 1100 . Frequently, this parameter is used to determine the degree of exhaustion of a carbon in use . However, this practice should be viewed with caution, as chemical interactions with the adsorbate may affect the iodine uptake, giving false results . Thus, the use of iodine number as a measure of the degree of exhaustion of a carbon bed can only be recommended if it has been shown to be free of chemical interactions with adsorbates and if an experimental correlation between iodine number and the degree of exhaustion has been determined for the particular application . </P> <P> Some carbons are more adept at adsorbing large molecules . Molasses number or molasses efficiency is a measure of the mesopore content of the activated carbon (greater than 20 Å, or larger than 2 nm) by adsorption of molasses from solution . A high molasses number indicates a high adsorption of big molecules (range 95--600). Caramel dp (decolorizing performance) is similar to molasses number . Molasses efficiency is reported as a percentage (range 40%--185%) and parallels molasses number (600 = 185%, 425 = 85%). The European molasses number (range 525--110) is inversely related to the North American molasses number . </P> <P> Molasses Number is a measure of the degree of decolorization of a standard molasses solution that has been diluted and standardized against standardized activated carbon . Due to the size of color bodies, the molasses number represents the potential pore volume available for larger adsorbing species . As all of the pore volume may not be available for adsorption in a particular waste water application, and as some of the adsorbate may enter smaller pores, it is not a good measure of the worth of a particular activated carbon for a specific application . Frequently, this parameter is useful in evaluating a series of active carbons for their rates of adsorption . Given two active carbons with similar pore volumes for adsorption, the one having the higher molasses number will usually have larger feeder pores resulting in more efficient transfer of adsorbate into the adsorption space . </P> <P> Tannins are a mixture of large and medium size molecules . Carbons with a combination of macropores and mesopores adsorb tannins . The ability of a carbon to adsorb tannins is reported in parts per million concentration (range 200 ppm--362 ppm). </P>

Where is carbon found in the reactivity series