Activated carbon preparation from ligno-cellusosic mixture of almond shell, apricot and peach stones by chemical activation

ABSTRACT Activated Carbon Preparation from Ligno-cellusosic Mixture of Almond Shell, Apricot and Peach Stones by Chemical Activation Activated carbons are the most widely used materials in industrial scale as an adsorbent, catalyst, catalyst support, electrode material, and so on, thus it has played an important role in the environmental applications, chemical, pharmaceutical and food industries due to their high surface area, pore volume and adsorption ability. Therefore, demand for activated carbon is increasing day by day. Activated carbons can be prepared from a variety of precursors with high carbon content and low inorganic compounds by physical and/or chemical activation. Activated carbon is relatively expensive product and its cost depends on the raw material, activation method and operational conditions used in its preparation. The cost generally limits widespread use of the activated carbon. Since unit operations for activation can not be changed, in order to achieve more cost-effective active carbon, very low or non-commercial availability of waste materials, agricultural by-products or residues is being investigated for this purpose nowadays. In this study, activated carbon was obtained in two stages from mixture of almond shell, apricot and peach stones by physical and chemical activation methods. In the first stage, activated carbon was prepared under pure carbon dioxide at different activation temperatures. In the second stage, it was prepared from the mixture subjected to chemical activation by ZnCl2 at different ZnCl2/grape stalk weight ratios, penetration times and temperatures at different carbonization temperatures and times under the pure carbon dioxide atmosphere. The obtained activated carbons were characterized by BET surface area, total pore volume, pore size, ash content, elemental analysis, pHzpc, FTIR, Boehm titration, thermogravimetric (TG) and SEM analysis. According to results obtained, it has been determined that active carbons having satisfactory properties with physical activation can not be obtained but it can be obtained by ZnCl2 chemical activation. In particular, it has been found that impregnation rate, duration and temperature and carbonization temperature have a significant effect on the activated carbon properties. Activated carbons with commercial properties could be obtained by chemically activating at the conditions of ZnCl2/mixture weight ratio of 15/40 and over at 25°C for 24 hours and carbonized at for 700°C for 60 minutes. The activated carbons obtained under these conditions have the following characteristics: BET surface area from 792.33 to 2073.04 m2/g, total pore volume from 0.2302 to 1.0918 cm3/g, por size from 1.8332 to 2.4700 nm, ash content from 0.16 to 0.30 %, pHzpc value from 5.68 to 6.59 and acidic surface functional groups. Key Words: Activated Carbon; Pyrolysis, Almond Shell, Peach Stone, Apricot Stone, Activation, Carbonization