Exploring macroporosity and partial mesoporosity in carbon materials through thermoporometry with menthol

Abstract

This study explores using menthol as a novel solid probe in thermoporometry (TPM) to analyze meso- and macroporosity in carbonaceous materials, which is traditionally challenging for conventional liquid probes like water. Four carbon samples with varying pore sizes were characterized to assess ability of menthol to complement traditional methods such as nitrogen physisorption, mercury intrusion, and scanning electron microscopy (SEM) techniques. The results showed that menthol has a detection range from 20 nm to 1500 nm. This allows it to effectively and accurately identify macropores and large mesopores. Optimizing conditions — sample drying, contact time, and heating rate — was essential for accurate results. Pre-drying the carbon samples at 195 °C for 1–4 days minimized moisture interference, and a contact time of 1 h proved sufficient for pore filling. A heating rate of 1 °C min⁻¹ was found to offer optimal peak resolution and baseline stability in DSC curves. The findings suggest that menthol-based TPM is a reliable alternative to traditional methods, expanding the scope of porosity analysis in carbon materials and enabling the effective characterization of larger pores. This study establishes menthol's potential as a versatile probe in TPM, offering a new approach to the comprehensive characterization of porous structures.