Structure evolution of carbon black under ionic-liquid-assisted microwave irradiation

The interactions between the carbon black (CB) and the ionic liquid (IL), 1-butyl-3-methyl-imiazolium hexafluorophosphate ([BMIM⁺][PF₆⁻]), are firstly examined. The CB, mixed with the IL via simple blending, is then subjected to microwave (MW) irradiation to prepare the modified CB. The structure evolutions of the modified CB such as the microcrystalline structure and surface chemistry are revealed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and pore analysis. After mixing but before MW irradiation, the microcrystalline arrangement of CB turns to be more ordering and microcrystalline size (La) to be a little bigger but with a limited degree. Under MW irradiation, the IL undergoes severe decomposition. The combination of localized high temperature (proposed to be higher than 425 °C) and the decomposition of the IL leads to substantial structure changes of the CB. The graphitization of the CB surface, the disordering of the microcrystalline and the decrease in La are disclosed. In addition, compared with the untreated CB, the CB treated with IL-assisted MW irradiation is found to have much higher volume of the smaller mesopore.