Impact of carbon micro/mesoporosity on the adsorption behavior of small molecules

Abstract

Adsorption studies on carbon play a key role in fields such as environmental remediation, purification, and catalysis. Because of the inherently high surface area, low cost, and inertness of activated carbons, these materials have been the preferable substrate for remediation studies. The adsorption of mercury, radioactive materials, pesticides, and dyes from soil and water are only a few examples among others. Considerably less time has been dedicated to investigating adsorption processes on other types of carbons such as carbon blacks, graphene, or carbon nanotubes, despite the fact that these materials are used extensively in energy conversion and storage devices, and applications in the field of catalysis and electrocatalysis. This thesis work is aimed to fill the gap in existing research by studying the adsorption of two model molecules, glucose (C6H12O6) and melamine (C3H6N6) onto three different wellcharacterized carbon substrates, two commercial carbon materials with very different properties, Darco KB-G (AC) and Vulcan XC-72R (VC), and a mesoporous carbon synthesized for this purpose. The adsorption of glucose was examined using both gas chromatography and thermogravimetric analysis, while melamine adsorption was studied using UV-visible spectroscopy. The effect of different phase separation techniques on TGA results was analyzed. Melamine adsorption isotherms in both acid and alkaline media were fit with both the Langmuir and Freundlich models. To the best of our knowledge, these are the first reported values for the adsorption of melamine on mesoporous carbon materials.