porenvolume

Porenvolume, or pore volume, is the total volume of void spaces within a solid material. It is a key parameter for porous materials and is commonly reported as either a volume per mass (for example cm3/g) or as the fraction of the bulk volume that is void (porosity). The total pore volume Vp includes all pores that can contain a fluid, including isolated pores, while the accessible pore volume refers to pores connected to the exterior or to a chosen probe.

The porosity φ is defined as φ = Vp / Vt, where Vt is the bulk or total volume of the material. Pores are often categorized by size: micropores (<2 nm), mesopores (2–50 nm), and macropores (>50 nm). A pore size distribution describes how pore volume is distributed across those sizes and is important for diffusion and adsorption properties.

Measurement approaches include mercury intrusion porosimetry, which yields pore-throat diameter distributions and cumulative pore volume; gas adsorption techniques (for example nitrogen or argon at cryogenic temperatures) to quantify micro- and mesopore volumes using BET and related methods; and indirect methods such as liquid saturation or optical methods for total pore volume. Helium pycnometry can determine skeletal (solid) volume to help derive porosity when the total volume is known.

Applications span catalysis, adsorption and filtration, energy storage, cement and ceramics, and soil science. Pore connectivity, tortuosity, and pore throat size influence transport properties and practical performance, making pore volume a foundational metric in characterizing porous materials.