(1) The impregnated sample was carbonized in the furnace at 250ºC for 100 min of the approximate heating rate 10-12 ºC/min; (2) The temperature of activation was increased up to 800 ºC under N2 flow of 80 cm3/min and maintained for 2 h then cooled to room temperature; (3) The product was washed with 0.1 mol/L HCl to remove residual chemicals then filtered and washed with distilled water until neutral pH; (4) The product was then dried in oven for 24 h before doing characterization.