Functionalization of surface of carbon materials with bromine vapors at mediate high temperature: a thermogravimetric study

Carbon materials (CMs) of different classes, namely multiwall carbon nanotubes, activated carbon and carbon black were subjected to the vapor bromination at temperatures of 200–500 °C. The results showed that, in the aforementioned temperatures range, 0.4–2.2 mmol g−1 of bromine functionalized the surface of CMs. The optimal temperature interval of the bromination that caused the bromine chemisorption was determined to be 300–500 °C. The kinetics of the bromination of CMs was investigated by thermogravimetry at 200, 300, 400 and 500 °C. The bromination of CMs realizes at two different kinetic regimes. The fast reaction of the bromine vapor with CMs realizes at the first 30–35 min of the bromination and causes chemisorption of 65–80 mass% of bromine. The slow process of the bromination realizes at the subsequent 120 min when the bromine reacts with the CMs surface in tight micropores. The kinetic parameters of the bromination of CMs that are characterized by two regimes of the process were determined at the temperature interval of 200–500 °C. The amination of the brominated CMs with diethylamine causes replacement of the surface-grafted bromine on the amine residues and gives CMs with 0.3–1.7 mmol g−1 of diethylamino groups.