Eco-Friendly Polysaccharides as Moisture Retainers: Influence on Humic Acid Colloidal Stability in Model and Natural Systems

Hyaluronic acid and carboxymethyl cellulose are eco-friendly polysaccharides known for their excellent moisture retention properties, making them suitable components of agricultural fertilizers. On the other hand, humic acids exhibit surface-active properties, suggesting their potential to replace synthetic surfactants in agricultural applications. Naturally, the interaction between polysaccharides and humic substances influences their colloidal and chemical behavior. The mutual interactions between humic acids and these polysaccharides were examined at immiscible liquid interfaces and on plant leaf surfaces using radiotracer analysis and tensiometry (pendant drop and sessile drop methods). The results indicate that humic acids achieve optimal adsorption at a hyaluronic acid concentration of 30 g/L, regardless of molecular weight. In contrast, carboxymethyl cellulose reduces the surface activity of humic acids. Additionally, a combined solution of humic acids and hyaluronic acid improves the wetting efficiency of wheat leaves compared to individual solutions. However, humic acids showed minimal impact on the absorption or systemic distribution of hyaluronic acid within the plant.