Thermodynamic Study of Methylene Blue Adsorption on Carbon Nanotubes Using Isothermal Titration Calorimetry: A Simple and Rigorous Approach
| Autor: | Luiz C.A. Oliveira, Glaura G. Silva, João Paulo C. Trigueiro, Rodrigo L. Lavall, Merly Rita dos Santos, Paulo F.R. Ortega, Ângelo M. L. Denadai, Ana Paula C. Teixeira |
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| Rok vydání: | 2017 |
| Předmět: |
Nanotube
Exothermic process General Chemical Engineering Thermodynamics Isothermal titration calorimetry 02 engineering and technology General Chemistry Carbon nanotube 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Endothermic process 0104 chemical sciences law.invention Dilution chemistry.chemical_compound Adsorption chemistry law Physical chemistry 0210 nano-technology Methylene blue |
| Zdroj: | Journal of Chemical & Engineering Data. 62:729-737 |
| ISSN: | 1520-5134 0021-9568 |
| Popis: | In this article, a thermodynamic study of the methylene blue (MB) adsorption on carbon nanotubes (CNT), a known model system, was carried out by using a simple and rigorous experimental approach based on adsorption and isothermal titration calorimetry (ITC) experiments. Considering the thermodynamics of the process, the classical approach using the van’t Hoff approximation provided endothermic values for ΔadsH0 while the ITC measurements revealed that the adsorption of MB on both unmodified and acid-modified CNTs is an exothermic process. The thermodynamic parameters for the systems were obtained using the infinite dilution regime and ITC data: ΔadsH0 = −9.13 ± 0.02 kJ mol–1, ΔadsG0 = −21.18 ± 0.61 kJ mol–1, and ΔadsS0 = 40.42 ± 0.61 J K–1 mol–1 for u-CNT and ΔadsH0 = −11.49 ± 0.34 kJ mol–1, ΔadsG0 = −27.88 ± 0.18 kJ mol–1, and ΔadsS0 = 54.97 ± 0.38 J K–1 mol–1 for f-CNT. The process is both enthalpically and entropically driven, having a more negative ΔadsG0 for the system based on a modified nanotube. W... |
| Databáze: | OpenAIRE |
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