A Fractal-Modified Dubinin-Astakhov Equation for Micropores Adsorption in Porous Media: Principle, Methodology and Implication

The previous Dubinin-Astakhov (D-A) equation for micropores adsorption in porous media is derived based on Polanyi adsorption potential theory, which does not involve the influence of the heterogeneous parameters and fractal properties of micropore structures on gas adsorption. In this research, a novel fractal-modified D-A equation is proposed based on the fractal characteristics of micropore heterogeneity. The principle and methodology of fractal-modified D-A equation are constructed and summarized. The research results indicate that the proposed equation is the function of the fractal dimension [Formula: see text] for the micropore tortuosity, fractal dimension [Formula: see text] for the micropore size, and micropore structure parameters (the minimum micropore diameter ?min and maximum micropore diameter [Formula: see text]), which more comprehensively reflects the influence of micropore structure on multi-layer filling adsorption. Significantly, the proposed equation achieves new progresses in determining the critical pressure [Formula: see text] for the variation from monolayer adsorption to micropore multi-layer filling adsorption, calculating the adsorption capacity in micropores with different pore diameter ranges, and the CO 2 adsorption capacity of micropores with a pore size greater than 0.5 nm is significantly higher than that of micropores with a pore size less than 0.5nm. The proposed equation provides a theoretical basis and methodological reference for further research on gas adsorption behavior in porous media.