Tortuosity of the porous structure of carbon gels

Extensive studies on the correlation between synthesis variables and the final properties of resorcinol-formaldehyde carbon gels have been performed. This knowledge allows us to obtain carbon gels with analogous mean pore sizes and porosity from different combinations of synthesis variables. However, although the materials exhibit these similar characteristics, their behaviors may be very different in certain applications. Since the distribution and connectivity of the polymeric clusters are strongly affected by variables such as the amount of water and methanol in the precursor solution, it seems that the pore tortuosity and thus the permeability of the materials are also dependent on these factors. Further analysis of a series of carbon gels with the apparent same porosity shows how an increase in the amount of water or a suitable combination of methanol content and the pH of the precursor solution used for the polymerization process generate less tortuous pore structures. This allows us to attain even finer tuning of the porous structure of RF carbon gels either to reduce pressure drop or to increase the residence time of solutes in separation processes. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Extensive studies have been conducted on the correlation between synthesis variables and the final properties of resorcinol-formaldehyde carbon gels. Different combinations of synthesis variables can lead to carbon gels with similar pore sizes and porosity, but their behaviors in applications may vary. The distribution and connectivity of polymeric clusters are strongly influenced by factors such as water and methanol content in the precursor solution, affecting pore tortuosity and material permeability. Increasing water content or using a suitable combination of methanol content and precursor solution pH during the polymerization process can result in less tortuous pore structures in carbon gels with the same porosity.