Comment on “Fabrication of a Solid Amine Microspherical Adsorbent with High CO ₂ Adsorption Capacity via Water-in-Water Emulsion Templating”

The adsorption of CO 2 on laboratory-synthesized adsorbents has attracted considerable attention over the past decade. In a recent article [ ACS Appl. Polym. Mater. 2025, 7 (2), 923−931], Chen et al. investigated CO 2 adsorption on amine-loaded adsorbents prepared under varying synthesis conditions, with emphasis on kinetic modeling using empirical and diffusion-based models. This Comment raises concerns regarding the use of three diffusion-based models in that study. Specifically, the Boyd film diffusion model, the interparticle diffusion model, and the Weber–Morris intraparticle diffusion model are shown to be misrepresented or misapplied. Equations identified as describing film diffusion correspond instead to approximations originally proposed for intraparticle diffusion, while the so-called interparticle diffusion model is mathematically equivalent to the same approximation. Moreover, the Weber–Morris expression employed in the study is a corrupted form of the original equation. The suitability of applying diffusion-based models developed for batch uptake curves to breakthrough data obtained from a fixed-bed apparatus is also examined.