CEC analysis was performed using the following method: The ground char sample was thoroughly mixed and 2 g was placed in a 250-mL Erlenmeyer flask. Hundred milliliters of 0.5 N HCl was added, the flask was covered with parafilm and shaken vigorously periodically for 2 h. Sample was filtered using a glass fiber fi. ter in a Buchner funnel, washing with 100 mL portions of H2O until wash shows no precipitate with AgNO3. Filtrate was discarded. Moist char was immediately transferred to a clean 250-mL Erlenmeyer flask and a total of 100 mL 0.5 N Ba(OAc)2 was added and a stopper placed on the flask. The mixture was shaken vigorously periodically for 1 h and was filtered, washing with three 100 mL portions H2O. The char was discarded, and the filtrate was titrated with 0.0714 N NaOH using phenolphthalein to first pink. The following equation was used to calculate the CEC value:

milliequivalent mL x normality NaOH x 100 (1)

100g air — dried char (g) sample