Characterization of Activated Carbons Produced from Oleaster Stones

Abstract

Activated carbon has a porous structure surrounded by carbon atoms and therefore is a material with adsorbent capability. The most important parameter that is put into consideration to investigate its chemical characterization is porosity. Pore size determines how adsorption takes place in pores (Marsh & Reinoso, 2006). In accordance with IUPAC, pores are classified into three different sizes. Pores less than 2,0 nm are classified as micropores, those in the range of 2,0-50 nm mesopores and those greater than 50 nm macropores (IUPAC). The selection of raw material for the production of activated carbon is made on the basis of carbon amount, mineral matter and sulfur content, availability, cost, and shelf life (Kroschwitz,1992). Raw material may be of vegetable, animal and mineral origin and the production can be carried out by means of physical and chemical activation depending on the type of raw material. The physical activation method generally involves carbonization and activation stages (Singh, 2001). In the activation stage oxidizing agents are used such as carbondioxide and steam and thus form pores and canals (Jankowska et al., 1991). Chemical activation involves a carbonization stage where a chemical activating agent that is in the form of a solution or dry is blended with the raw material. Chemicals employed in chemical activation (potassium hydroxide, phosphoric acid, zinc chloride etc.) are effective at decomposing the structure of the raw material and forming micropores (Marsh & Reinoso, 2006). The literature has many articles dealing with activated carbons produced from raw material using both the chemical and physical activation methods. Materials frequently used as raw material of vegetable origin include corncobs (Sun et al., 2007; Aworn et al., 2009; Preethi et al., 2006), hazelnuts (Demiral et al., 2008; Soleimani & Kaghazchi, 2007), olives (Yavuz et al., 2010), nuts (Yeganeh et al., 2006; Aygun et al., 2003), peaches (Kim, 2004), loquat stones (Sutcu & Demiral, 2009), wood (Ould-Idriss et al., 2011; Sun & Jiang, 2010) and bamboo (Ip et al., 2008), those of animal origin bones (Moreno-Pirajan et al., 2010) and hide waste (Demiral & Demiral, 2008), and those of mineral origin coal (Alcaniz-Monge et al., 2010; Cuhadaroglu & Uygun, 2008; Liu et al., 2007; Sutcu & Dural, 2007), petroleum coke (Lu et al., 2010) and rubber (Gupta et al., 2011; Nabais et al., 2010). In this study I produced activated carbons from chars obtained through the carbonization of oleaster stones by physical, chemical and chemical+physical activation, and performed their surface characterization.