Influence of activation atmosphere used in the chemical activation of almond shell on the characteristics and adsorption performance of activated carbons

Abstract

7 pages, 5 figures, 5 tables.The aim of this work was to compare the effect of different activating atmospheres on the final properties and adsorption performance of activated carbons. Almond shell based activated carbons have been obtained by chemical activation with phosphoric acid. Two sets of activated carbons were prepared. First set was prepared under inert atmosphere at different impregnation ratios, temperatures and times of activation. Second set of activated carbons was prepared at the same activating conditions except the activating atmosphere using an oxidant one. Activated carbons prepared under both activation atmospheres were characterized by elemental analysis (EA), thermogravimetry (TGA), temperature programmed desorption (TPD), point zero charge (PZC), Boehm titration and N 2 physisorption. To study the adsorption performance of the activated carbons toluene adsorption – desorption isotherms were determined gravimetrically. The results obtained con fi rm that the activating atmosphere has a strong in fl uence on the fi nal characteristics of the activated carbons. Activated carbons with higher oxygen content and more negative surface charge have been obtained by changing the activatingatmospherebyanoxidantone.Surfaceareaisalsohigherforactivatedcarbonspreparedunderoxidant atmosphere. However toluene adsorption capacity is lower for activated carbons prepared under oxidant atmo- sphere due to their surface chemistry. © 2013 Elsevier B.V. All rights reserved.The financial support from Spanish Ministry of Environment (contracts 439/2006/3- 11.2 and B030/2007/2-11.2) is duly recognized.Peer reviewe