BJH (rus. метод ВJH) — method of calculating pore size distribution in a porous material using adsorption or desorption isotherms.


The method of Barrett-Joyner-Halenda (BJH), proposed in 1951, was originally designed for relatively wide-pore adsorbents with a wide pore size distribution. However, it was repeatedly demonstrated that it can be successfully applied to virtually all types of porous materials. The model is based on the assumption that pores have a cylindrical shape and that pore radius is equal to the sum of the Kelvin radius and the thickness of the film adsorbed on the pore wall [1]. The desorption branch of isotherm in the pressure range (0.4-0.967)  *) is generally used as initial data for BJH calculations (although the use of the adsorption branch is also possible).

In this calculation pores with a diameter above 60 nm are not considered.

*) is the ratio of partial pressure of the adsorbed substance to saturated vapour pressure of the adsorbed gas.


  • Smirnov Andrey V.
  • Tolkachev Nikolay N.


  1. Barrett E. P. et al. The determination of pore volume and area distributions in porous substances. I. Computations from nitrogen isotherms // J. Am. Chem. Soc. 1951. V. 73. P. 373–380.
  2. Aligizaki Kalliopi K. Pore Structure of Cement-Based Materials: Testing Interpretation and Requirements (Modern Concrete Technology). — Taylor & Francis, 2005. — 432 p.

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