2.3 Iodine number (Iodine test) The Iodine test is a test method that covers the determination of the relative activation level of activated carbons by the adsorption of iodine from aqueous solution. The amount of iodine adsorbed (in milligrams) by 1g of carbon using test conditions is called the iodine number. The iodine number is a relative indicator of porosity in an activated carbon. Iodine number is a rough measure of capacity of small molecules and correlates with surface area (Keller et al., 1987) and may be used as an approximation of surface area for activated carbons. Here, a standard iodine solution was treated with three different known weights of activated carbon under laboratory conditions. The carbon treated solutions were filtered to separate the carbon from treated iodine solution (filtrate). The remaining iodine in the filtrate was measured by titration. The amount of iodine removed per gram of activated carbon was determined for each dosage and the average taken. Also the resulting data was used to plot an adsorption isotherm. The steps taken in determining iodine number test are clearly spelt out in Figure 2.