Understanding Sorption Mechanisms Directly from Isotherms.

Area of Science:

• Surface Science
• Physical Chemistry
• Materials Science

Background:

• Numerous isotherm models exist, often leading to ambiguous mechanistic interpretations when fitting experimental data.
• Traditional models like Langmuir, BET, and GAB are frequently misapplied to complex systems, violating their core assumptions.
• Determining surface area using site-specific models and sorbate cross-sectional areas can yield contradictory results.

Purpose of the Study:

• To develop a universal framework for modeling all six IUPAC isotherm types.
• To systematically attribute isotherm differences to sorbate-sorbate and sorbate-surface interactions.
• To resolve contradictions arising from the application of traditional, site-specific adsorption models.

Main Methods:

• Generalizing traditional sorption model parameters into model-free concepts.
• Introducing partitioning and association coefficients applicable across all isotherm types.
• Developing a unified approach to analyze gas adsorption data.

Main Results:

• A universal approach successfully models all isotherm types, unifying over 100 existing models.
• The generalized coefficients systematically account for sorbate-sorbate and sorbate-surface interactions.
• Contradictions in surface area determination using traditional models are eliminated.

Conclusions:

• The proposed universal approach offers mechanistic insights into gas adsorption phenomena.
• This framework provides a consistent method for analyzing adsorption data across diverse systems.
• It resolves limitations of traditional models and enhances the reliability of surface area determination.