AN ADSORPTION MODEL CONSIDERING THE COMPLEXITY OF SOLID PARTICLES AND PORE STRUCTURE

The gas adsorption capacity of porous media is significantly influenced by the complex pore structure and the size of solid particles. Despite this, a comprehensive adsorption model that captures the relationship between pore structure, solid particles, and adsorption capacity is lacking. Therefore, integrating fractal theory, a fractal particle with capillaries model is proposed. This structure is more consistent with the real adsorption of gas in porous media. In the fractal particle with capillaries model, gas adsorption begins with the smallest apertures and progresses to larger ones as the adsorption pressure increases. By integrating Langmuir theory with the Kelvin equation, we establish an adsorption model that accounts for the complexities of solid particles and pore structures. Our research reveals that as adsorption pressure increases, the adsorption isotherm can display three distinct growth patterns: exponential, reverse S-shaped and logarithmic. These patterns address the limitations of the Langmuir equation, which can only characterize adsorption isotherms with logarithmic growth. Additionally, the study explores how factors such as the capillary fractal dimension, solid particle fractal dimension, bending fractal dimension, and solid particle diameter influence adsorption capacity. The results indicate that higher capillary fractal dimensions, solid particle fractal dimensions, and tortuosity fractal dimensions correspond to more intricate pore structures, which lead to a greater internal surface area and enhanced adsorption capacity. And, smaller particle diameters contribute to increased adsorption capacity. Finally, fitting the model to real experimental data reveals that the established adsorption model performs effectively, demonstrating strong applicability and accuracy.