Optimizing surface adsorption dynamics of aramid fibers using a surfactant adsorption-diffusion kinetic model

Adsorption, a ubiquitous process across disciplines from chemistry to papermaking and pharmaceuticals, remains a cornerstone in material science. Despite the prevalence of the molecular adsorption-diffusion kinetics model, its exploration into the intricate adsorption dynamics on aramid fibers has been notably limited. This study proposes a surfactant adsorption-diffusion kinetic model designed to quantitatively evaluate the adsorption capacity of aramid fibers. We commenced by unraveling the dynamic adsorption behavior of the gemini quaternary ammonium salt (GS-A6) surfactant on pure water surfaces, leveraging the Szyszkowski equation, Gibbs adsorption isotherm, and Langmuir isotherm as analytical tools. Subsequently, we derived a comprehensive understanding of the dynamic adsorption-diffusion mechanism of GS-A6 aqueous solutions, grounded firmly in the adsorption-diffusion kinetics model. Employing this model in conjunction with the solid/liquid interface adsorption equation, we meticulously calculated the adsorption capacity of aramid fibers towards GS-A6. Analysis of the aramid fiber/GS-A6 aqueous solutions revealed a fascinating interplay: the long chain alkyl of GS-A6 harnessed hydrophobic interactions and van der Waals forces to anchor onto the benzene rings or hydrocarbon groups adorning the aramid fiber surface. Concurrently, the quaternary ammonium salts migrated into the aqueous phase, forming hydrogen bonding with water molecules, thereby enhancing the hydrophilicity and surface wettability of the aramid fibers. Compared to pure water (87.69 degrees), the contact angle of the aramid fibers wetted by a 0.35 mol/m3 GS-A6 aqueous solution decreased to 81.69 degrees. This work offers a potent tool for evaluating and optimizing surface adsorption on aramid fibers, with implications for advanced material design across industries.