Enthalpic characterisation of activated carbon monoliths obtained from lignocellulosic materials

• Published in: Journal of thermal analysis and calorimetry 2013-02, Vol.111 (2), p.1067-1072
• Main Authors: Vargas, D. Diana Paola, Giraldo, G. Liliana, Moreno, P. Juan Carlos
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Comparative analysis; Exact sciences and technology; General and physical chemistry; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Surface physical chemistry
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-012-2513-1

In this study, energetic interactions between activated carbon monoliths and various liquids were evaluated by determining immersion enthalpies in C 6 H 6 , H 2 O and aqueous solutions of NaOH and HCl. Immersion enthalpies depend on both the surface chemistry and the interactions between specific groups, and were compared with results from volumetric titrations. Immersion enthalpies of activated carbon monoliths were between −95.85 and −176.5 J g −1 for C 6 H 6 and between −11.19 and −68.31 J g −1 for H 2 O; whereas immersion enthalpies in NaOH and HCl solutions were between −20.36 and −82.25 J g −1 and −18.81 and −96.16 J g −1 , respectively. In support of these results, a high level of acidic groups was found on the surface of the activated carbon monoliths by Boehm volumetric titrations, with values between 719 and 1,290 g mol −1 , in agreement with the higher immersion enthalpies observed in NaOH. Correlations were established between immersion enthalpies in the liquids and the surface chemistry properties of the activated carbon monoliths determined by volumetric titrations, demonstrating that immersion enthalpy is a useful parameter for characterisation of these materials in specific liquids.