Calorimetric study of functionalized carbonaceous materials

• Published in: Thermochimica acta 2015-07, Vol.611, p.20-25
• Main Authors: Vargas, Diana. P., Giraldo, L., Moreno-Piraján, J.C.
• Format: Article
• Language: English
• Subjects: Activated carbon; Calorimetry; Chemical surface; Functionalization
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2015.04.029

•The activated carbons were functionalized to increase the nitrogen.•The content of the carboxylic groups promotes the modification of activated carbons with ammonia and ammonium hydroxide.•The functionalization process that occurred in the carbon materials.•The functionalization with ammonia modified the characteristics of the original samples in a smaller proportion.•Was observed the utility of the calorimetric technique for the characterization of the carbonaceous materials. For this paper we conducted a calorimetric study of functionalized carbonaceous materials. The activated carbons were obtained by chemically activating the African Palm Stone with a mix of 2% CaCl2 solution and 32% H3PO4 solution. After the activation, the activated carbons were functionalized to increase the solids nitrogen content. In the study we determined the immersion enthalpies in benzene, water, NaOH, and HCl solutions. Additionally, the samples were characterized by N2 adsorption at 77K and Boehm titration. The calorimetric study showed that the immersion of different solids in respective solvents and solutions generated enthalpy values between −6.22Jg−1 and −173.2Jg−1. The immersion enthalpies of samples in the employed liquids varied with different functionalization processes to which the materials were subjected, showing changes in the carbons’ textural and chemical characteristics. Surface areas and pore volumes decreased with the functionalization process because of the nitrogen surface groups’ blocking the solids’ porosity.