JAMBULINGAM et al.: PROPERTIES OF ACTIVATED CARBONS FROM AGRICULTURAL WASTES 495 Characteristic studies of some activated carbons from agricultural wastes M Jambulingam 1, *, S Karthikeyan 2 , P Sivakumar 2 , J Kiruthika 3 and T Maiyalagan 4 1 PG & Research Department of Chemistry, PSG CAS, Coimbatore 2 Department of Chemistry, Erode Sengunthar Engineering College, Thudupathi, Erode 638 057 3 Department of Biotechnology, Government College of Technology, Coimbatore 4 Department of Chemistry, IIT Madras, Chennai Received 07 September 2005; revised 17 November 2006; accepted 20 February 2007 Agricultural wastes like tobacco stem, bulrush Scirpus acutus stem, Leucaena leucocephala shell, Ceiba pentandra shell, Pongamia pinnata shell have been explored for the preparation of activated carbon. Characterization studies such as bulk density, moisture, ash, fixed carbon, matter soluble in water, matter soluble in acid, pH, decolourising power, phenol number, ion exchange capacity, iron content and surface area have been carried out to assess the suitability of these carbons as absorbents in water and wastewater. The results obtained show them to be good adsorbents for both organics and inorganics. Present study reveals the recovery of valuable adsorbents from readily and cheaply available agriculture wastes. Keywords: Activated carbon, Adsorption, Agricultural wastes, Surface area IPC Code: C01B31/08 Introduction Ancient Hindus in India used charcoal for drinking water filtration and Egyptians used carbonized wood as a medical adsorbent and purifying agent as early as 1500 BC 1 . Activated carbon from vegetable material was introduced industrially in the first part of the 20 th century, and used in sugar refining 2 . In the US, activated carbon from black ash was found very effective in decolorizing liquids 3 . Agricultural by-products and waste materials used for the production of activated carbons include olive stones 4 , almond shells 5 , apricot and peach stones 6 , maize cob 7 , linseed straw 8 , saw dust 9 , rice hulls 10 , cashew nut hull 11 , cashew nut sheath 12 , coconut shells and jusks 13 , eucalyptus bark 14 , linseed cake 15 and tea waste ash 16 . Besides these, other sources of activated carbon are sulfonated coal 17 , tyre coal dust, activated bauxite, cement kiln dust 18 , ground sunflower stalk, shale oil ash, rubber seed coat, palm seed coat 19 , de-oiled soya 20 , baggase fly ash 21 , Red mud 22 etc. This study explores new activated carbon from biological waste materials through various processes. Materials and Methods Agricultural wastes (tobacco stem, bulrush Scirpus acutus stem, Leucaena leucocephala shell, Ceiba pentandra shell and Pongamia pinnata shell), collected from fallow lands in and around Erode District, Tamil Nadu, India, were cut into small pieces (3 cm), dried in sunlight and used for the preparation of activated carbons. The material to be carbonized was impregnated with respective salt solutions (ZnCl 2 , CaCl 2 , Na 2 SO 4 , Na 2 CO 3 ) for varying periods. Accordingly, sufficient quantities were soaked well with 10% salt solution (5 l capacity) respectively so that the solution gets well adsorbed for a period of 24 h. At the end of 24 h, excess solution was decanted off and air-dried. Then the materials were placed in muffle furnace carbonized at 400°C for 60 min. The dried materials were powdered and activated in a muffle furnace kept at 800°C for 60 min. After activation, the carbons obtained were washed sufficiently with 4N HCI. Then the materials were washed with plenty of water to remove excess acid, dried and powdered. In Dolomite process, sufficient quantities of dried agricultural wastes were taken over a calcium *Author for correspondence Tel: 0422-5397901-902 E-mail: jambupsggas@rediffmail.com Journal of Scientific & Industrial Research Vol. 66, June 2007, pp.495-500