Adsorptive removal of CO 2 on highly microporous activated carbons prepared from Eucalyptus camaldulensis wood: Effect of chemical activation Aghdas Heidari a , Habibollah Younesi a, *, Alimorad Rashidi b , AliAsghar Ghoreyshi c a Department of Environmental Science, Faculty of Natural Resources & Marine Science, Tarbiat Modares University, Imam Reza Street, P.O. Box 46414-356, Noor, Iran b Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Blvd. Azadi Sport Complex, P.O. Box 14665-1998, Tehran, Iran c Department of Chemical Engineering, Babol University of Technology, Babol, Iran 1. Introduction Activated carbon is an extremely versatile carbonaceous material that is widely used as adsorbent, catalyst and catalyst support in industries [1,2]. Moreover, its large surface area and micropore volume, favorable pore size distribution, surface chemistry including the oxygen functional groups, the degree of polarity and the active surface area lend AC appropriate as adsorbent for a variety of environmental applications, i.e. purification and storage of gases, removal of organic materials and metals from aqueous solution [3,4]. The adsorption efficiency of AC relies strongly on its special surface and structural characteristics. For example, AC utilized for the adsorption of gases and vapors should consist of pores with effective radii, significantly smaller than 16–20 A ˚ [5,6]. Activated carbon is mainly produced by thermal and chemical activation. Thermal or physical activation involves the primary carbonization of a carbonaceous precursor (below 700 8C) followed by the activation of the obtained char with oxidizing gases such as air, CO 2 or steam at high temperature in the range of 700–1100 8C. Chemical activation consists of the impregnation of raw material with chemical agents such as H 3 PO 4 , ZnCl 2 or KOH followed by carbonization at temperatures between 400 and 800 8C under a nitrogen atmosphere [4,7,8]. It is well-known that AC can be prepared by pyrolysis from a wide range of different carbon- containing source materials [7]. An enormous range of lignocellu- losic materials including rice husk [9], corn cobs [9,10] fruit stone [11,12], date stone [13], almond shell [14], coconut shell [15], sugar cane bagasse [16], palm shell [3], pistachio-nut shell [17,18] and cotton stalk [7] have been used as activated carbon precursors. Eucalyptus camaldulensis wood is a kind of lignocellulosic material which has a reasonably high content of carbon, utilized also as raw material for AC [19,20]. In this study, the potential of E. camaldulensis wood as precursor for the preparation of AC by chemical activation was investigated. Over the past years, a few reports have been published on preparation of AC from different parts of the Eucalyptus species; Patnukao [19] prepared AC with E. camaldulensis Dehn bark using phosphoric acid activation. Tancredi et al. [21] used Eucalyptus grandis sawdust for production of AC with CO 2 , CO 2 –O 2 and steam activation. Elyounssi et al. [22] Journal of the Taiwan Institute of Chemical Engineers xxx (2013) xxx–xxx A R T I C L E I N F O Article history: Received 20 February 2013 Received in revised form 8 May 2013 Accepted 3 June 2013 Available online xxx Keywords: Eucalyptus wood Activated carbon Pyrolysis Chemical activation CO 2 adsorption A B S T R A C T A series of activated carbons (ACs) were prepared from Eucalyptus camaldulensis wood by chemical activation with H 3 PO 4 , ZnCl 2 at different impregnation ratios as well as by pyrolysis, followed by activation with KOH. The porosity characteristics of these ACs were determined by N 2 adsorption isotherms. Through varying the H 3 PO 4 /biomass ratio from 1.5 to 2.5, the prepared ACs displayed BET surface areas in the range of 1875–2117 m 2 /g with micropores content of 69–97%. For the ZnCl 2 activated series, BET surface areas varying from 1274.8 to 2107.9 m 2 /g with micropores content of 93– 100% were obtained from impregnation ratios of 0.75–2.0. The AC obtained by KOH had the largest BET surface area of 2594 m 2 /g and the high micropore content of 98%. In addition, the FTIR and SEM analyses conducted for characterizing the ACs and the CO 2 adsorption onto all series of the eucalyptus wood based ACs at pressures ranging from 0 to 16 bar using a volumetric method were investigated. Also the effect of temperature (15–75 8C) on the amount of CO 2 adsorbed by the ACs that was prepared with H 3 PO 4 , KOH and ZnCl 2 was studied. The CO 2 adsorption capacity on the AC prepared with KOH was up to 4.10 mmol/g at 1 bar and 303 K, having an increase of about 63% in comparison with the commercial AC. ß 2013 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +98 0122 625 3101 3; fax: +98 0122 625 3499. E-mail addresses: hunesi@modares.ac.ir, hunesi@yahoo.com (H. Younesi). G Model JTICE-668; No. of Pages 10 Please cite this article in press as: Heidari, A., et al., Adsorptive removal of CO 2 on highly microporous activated carbons prepared from Eucalyptus camaldulensis wood: Effect of chemical activation. J. Taiwan Inst. Chem. Eng. (2013), http://dx.doi.org/10.1016/ j.jtice.2013.06.007 Contents lists available at SciVerse ScienceDirect Journal of the Taiwan Institute of Chemical Engineers jou r nal h o mep age: w ww.els evier .co m/lo c ate/jtic e 1876-1070/$ – see front matter ß 2013 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jtice.2013.06.007