Modelling and simulation of BET, BJH, and thermophysical properties via SEM analysis of Esparto and Diss-derived activated carbons

This work presents a new preliminary mathematical empirical model to estimate nanoscale BJH, BET, and thermophysical properties through minimally invasive analysis of SEM images. The method extracts pore shape factor, porosity, and pore size distributions from micrographs of activated carbons derived from Esparto and Diss. These descriptors estimate BET surface area and BJH pore size distributions, offering faster characterisation than traditional adsorption. Experimental BET areas were 953 m2/g (Esparto) and 754 m2/g (Diss). The model showed promising agreement: elliptic cylinder geometry gave 974.62 m2/g (2.3% difference) for Esparto and 793.95 m2/g (5.3% difference) for Diss. Experimental BJH analysis confirmed both carbons are microporous, with peak pore volumes at 1.57 nm (Esparto) and 1.52 nm (Diss). Simulated BJH distributions agreed reasonably: for Esparto, mean pore diameters ranged from 2.90 nm (ellipsoid) to 3.26 nm (elliptic cone), and from 2.89 nm to 3.33 nm for Diss, with standard deviations of 0.52–0.54 nm. Thermophysical analysis analysis revealed clear geometry–property relationships. For Esparto, compact ellipsoids (porosity 5%, density 0.49 g/cm3) suggested potentially higher thermal conductivity (0.18 W/m·K) and diffusivity (0.1341 mm2/s). Diss showed similar trends: prolate spheroids and ellipsoids (density 0.54 g/cm3) yielded the highest thermal conductivity (0.16 W/m·K) and diffusivity (0.1288 mm2/s). This SEM-based approach shows promise as a fast, scalable tool for porous material characterisation where conventional adsorption instrumentation is unavailable.