Adsorption of sulfur dioxide onto activated carbons prepared from oil-palm shells impregnated with potassium hydroxide

Adsorption of sulfur dioxide (SO2), a gaseous pollutant, onto activated carbons prepared from oil-palm shells pre-treated with potassium hydroxide (KOH) impregnation was studied. Experimental results showed that SO2 concentration and adsorption temperature affected significantly the amount of SO2 adsorbed and the equilibrium time. However, sample particle sizes influenced the equilibrium time (due to effect of diffusion rate) only. Desorption at the same temperature of adsorption and a higher temperature of 200 degreesC confirmed the presence of chemisorption due to pre-impregnation. Impregnation with different activation agents was found to have limited effect on the inorganic components of the sample. Compared with the activated carbon pre-treated with 30% phosphoric acid (H3PO4) that had larger BET and micropore surface areas, the sample impregnated with 10% KOH had a higher adsorptive capacity for SO2, which was closely related to the surface organic functional groups of the sample. In general, the activated carbon prepared from oil-palm shell impregnated with KOH was more effective for SO2 adsorption and its adsorptive capacity was comparable to some commercial activated carbons. (C) 2000 Society of Chemical Industry.