@article{Dai2026, 
author = {Chaozheng Dai},
title = {Research on solution adsorption theory based on statistical thermodynamics},
year = {2026},
journal = {Journal of Capital Normal University (Natural Science Edition)},
volume = {47},
number = {4},
pages = {39-52},
keywords = {solution adsorption theory, statistical mechanics, non-uniform adsorbent, adsorption of multi-component solutions, chromatographic retention rules},
url = {https://www.sciopen.com/article/10.19789/j.1004-9398.2026.04.005},
doi = {10.19789/j.1004-9398.2026.04.005},
abstract = {Solution adsorption theory, as the core teaching content of surface chemistry, serves as a crucial link between fundamental chemistry and application fields such as industrial separation, environmental governance, and material preparation. The quality of its teaching is of vital importance to the cultivation of talents in chemistry, chemical engineering, environmental science, and other related fields. However, there are significant contradictions in current teaching and research. For instance, when traditional gas-solid adsorption theories (such as Langmuir's molecular layer adsorption theory and Brunauer-Emmett-Teller (BET) multi-molecule adsorption theory, etc.) are directly applied to solution systems, logical contradictions arise due to the neglect of the solvent effect, substitution effect and other special properties of solutions. Moreover, the theoretical derivation is complex and lacks coverage of practical systems such as non-uniform adsorbents and multi-component solutions, resulting in a disconnection between theory and practice. To fill the current gap in teaching resources, this paper takes statistical thermodynamics as the core theoretical basis and constructs a systematic and complete teaching system for solution adsorption theory. In teaching, it is essential to first clarify the three core assumptions. (1) The essence of solution adsorption is the monolayer adsorption of solutes at the interface, and the chemical potential of solutes is equal at equilibrium. (2) The intermolecular interaction energy is composed of van der Waals forces and hydrogen bonds, and the coordination number is directly proportional to the volume fraction of the components. (3) The surface of the non-uniform adsorbent is a collection of multiple types of active centers, and the total adsorption capacity is the linear superposition of the adsorption capacities of each center. Based on the uniform potential model (liquid phase) and the ideal potential well model (adsorption state), the derivation process of the monolayer adsorption equation for binary solutions is simplified, making the physical meaning of the equation clearer. At low concentrations, it conforms to Henry's law, and at high concentrations, it approaches the saturated adsorption capacity, which is in line with the essential characteristics of monolayer adsorption. On this basis, the teaching content of the theoretical boundary was further expanded. The adsorption equation of non-uniform adsorbents and the adsorption equation of multi-component solutions were established. To verify the validity of the theory, multi-dimensional experimental verification was carried out simultaneously. The adsorption experiments covered 7 types of adsorbates, including aniline, phenol and cyclohexanol, and 6 types of carbon material adsorbents, and combined a large number of chromatographic experiments, temperature effect studies and system verifications of adsorption of organic acids, alcohols and alkali metal ions. The results show that the theoretical calculated values are highly consistent with the experimental values, confirming that the solution adsorption is monolayer adsorption rather than the multi-molecular adsorption as traditionally understood. In addition, the universality of the theory in different adsorption systems was further verified through the adsorption of acetic acid by bone charcoal, the adsorption of alkali metal ions by silica gel, and the adsorption of n-butanol by blood charcoal, and the influence mechanisms of factors such as temperature, molecular structure, and the active center of the adsorbent on the adsorption behavior were clarified. The theoretical system of solution adsorption constructed in this paper not only provides a concise and systematic teaching tool for related majors in colleges and universities, but also helps students quickly master the core principles. At the same time, it provides scientific guidance for practical applications and demonstrates significant application value in fields such as liquid chromatography retention value prediction and adsorption separation process optimization.}
}