I milled two activated carbons, with different main sources (shell nutt and bituminous coal). The shell nut AC did not increase in surface area but had some degree of amorphization after milling. Still, the bituminous coal AC remains the same in graphitization, but the surface area is duplicated. Can changes in surface structure alter the surface area measured by BET method? Does the amorphization remove micropores and then reduce surface area? And the main source could influence this result and how?
Dear friend Antonio Ilderlânio de Sousa Leite
Surface area and amorphization degree in high-energy ball-milled activated carbon can indeed be related, and the main source can influence this relationship. When milling activated carbons from different sources, such as shell nut and bituminous coal, variations in surface area and amorphization can occur due to differences in their intrinsic properties.
Regarding your Antonio Ilderlânio de Sousa Leite observation, it's intriguing that while the shell nut activated carbon didn't increase in surface area, it exhibited some degree of amorphization post-milling. Conversely, the bituminous coal activated carbon maintained its graphitic structure but showed a doubling in surface area.
Firstly, changes in surface structure can indeed impact the surface area measured by the BET method. Amorphization, characterized by the disruption of the ordered carbon structure, can lead to the creation of new surface sites and defects, potentially increasing the measured surface area despite a reduction in crystallinity.
Secondly, it's plausible that amorphization could remove micropores, especially if the milling process is severe. Micropores are inherently part of the porous structure of activated carbon and contribute significantly to its surface area. Therefore, their removal could result in a decrease in measured surface area.
The influence of the main carbon source on these results is multifaceted. Differences in precursor materials can lead to variations in the initial structure and composition of the activated carbon. This variance can affect how the carbon responds to the milling process, impacting factors such as the extent of amorphization and the preservation of micropores. For instance, bituminous coal may have a more robust crystalline structure that resists amorphization, while shell nut-derived activated carbon may be more prone to structural changes.
In conclusion, the relationship between surface area and amorphization in high-energy ball-milled activated carbon is complex and influenced by factors such as the carbon source and the milling conditions. Understanding these relationships is crucial for tailoring activated carbon properties for specific applications.
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