Chemical and Process Engineering Research www.iiste.org ISSN 2224-7467 (Paper) ISSN 2225-0913 (Online) Vol.56, 2018 24 Effect of Activation Method and Agent on the Characterization of Prewinkle Shell Activated Carbon Akpa, Jackson Gunorubon Dagde, Kenneth Kekpugile Department of Chemical/Petrochemical Engineering, Rivers State University, Port-Harcourt, Rivers State, Nigeria Abstract The effect of activation method (physical and chemical) and the concentration of the chemical activating agents on the characterization of periwinkle shell activated carbon was investigated. The periwinkle shell was pyrolysed and activated by physical activation (using an oxidizing gas - steam) and chemical activation (using base: ZnCl 2 , CaCl 2 and acid: H 2 SO 4 , HCl). The produced activated carbons were characterized to determine the bulk density, moisture content, pore volume, porosity, ash content, iodine number and surface area following standard ASTM procedures. The effects of concentration of the activating agents on these properties were also studied. Effects of activation method on activation carbon properties showed that the chemical activated carbon had higher bulk density, pore volume, porosity, ash content, iodine number, and surface area, while the physical activated carbon had higher moisture content. The effect of activating agent concentration showed that the bulk density, pore volume and porosity increased with concentration for base activated carbon and decreased with concentration for acid activated carbon. The ash content and iodine number fluctuated (initial increase then decrease and increase) for base activated carbon; while these parameters increased continuously and fluctuated (initial decrease the continuous increase) with concentration for acid activated carbon. The moisture content and surface area decreased with concentration for base activated carbon; these parameters fluctuated (initial increase, decrease then increase) and increased continuously for acid activated carbon. Periwinkle shell carbon chemically activated with ZnCl 2 was the best activated carbon with highest density, pore volume, porosity, iodine number and surface area. Keywords: Activated carbon, Physical and Chemical activation, effect of activation agent concentration. 1. INTRODUCTION Activated carbon (activated charcoal) is a form of carbon processed to be extremely porous, increasing its surface area for adsorption or chemical reactions. It is composed primarily of carbon atoms and can be produced from any material with high carbon content. Such material includes hard/soft wood, lignite and coal. The use of waste materials that have no competing demands and environmental concerns has necessitated the use of such waste materials with high carbon content for the production of activated carbon. These materials include industrial waste, agricultural by-products and residual wastes such as paper mill sludge, bagasses fly ash-a sugar industry waste, rice husk, date and peat stones, oil palm waste, palm kernel fiber and shell, coconut shell, periwinkle shell, snail shell, waste bamboo etc. The intrinsic pore network in the lattice of these materials after been processed ensures the removal of impurities from gaseous and liquid media. Activated carbons are generally prepared by the carbonization of raw organic, carbonaceous starting materials in an inert atmosphere followed by the activation of carbonized product/char. The carbonization creates initial porosity and orders the carbon structure to enrich the carbon material; the activation enhances the carbon structure by widening the pores, making it more porous (Daud & Ali, 2004). Carbonation involves pyrolysis of the raw material at a temperature range of 600 - 900 o C in the absence of oxygen (in inert atmosphere with gases like argon or nitrogen) during which volatile components are removed, producing a residual carbonaceous product with low surface area. Activation can be performed either by physical/thermal or chemical methods (Rahim, et al., 2008). Physical activation process involves treatment of the char obtained from carbonization with gasification reactants/oxidizing gases such as steam, carbon dioxide, air or a suitable combination (Ahmida, et al., 2015) at high temperature (400 - 1000 o C) (Ahmad, et al., 2015). The porous activated carbon is produced when the oxidant converts the carbon materials to form carbon mono-oxide (CO) and carbon dioxide (CO 2 ) thus opening pores in the activated carbon materials. Chemical activation process involves treatment of the char obtained from the carbonization with chemicals such as alkali and alkaline earth metal containing substances (KOH, NaOH, and Na 2 CO 3 ), acid (H 3 PO 4 , HCl, H 2 SO 4 and C 2 H 4 O 2 ) and other chemicals/salts (ZnCl 2 , CaCl 2 etc), the chemicals functioning as dehydrating or oxidizing agents, influencing the pyrolytic decomposition and inhibiting the formation of tar. This process is usually done at lower temperature (500 o C to 800 o C) and activation time, giving higher carbon yields, surface area, better porosity and lower energy cost as compared to physical activation (Ahmad, et al., 2015). Activated carbon is widely used in domestic, commercial and industrial settings (Mendez et al., 2006), these include the food industry where activated carbon is used in de-colourization, deodorization and taste removal; to