Deep Eutectic Solvents as More Sustainable Dispersion Media for Beeswax Coatings from Cultural Heritage: Experimental Insights and Theoretical Modeling

Deep eutectic solvents (DESs) are gaining attention as sustainable alternatives to traditional organic solvents, particularly for applications involving nonpolar substances. In this study, the dispersion behavior of beeswax in a selection of hydrophobic natural deep eutectic solvents (hNADESs) was investigated using both theoretical and experimental approaches. The compatibility between each DES and beeswax was first assessed through Hansen solubility parameters and RED (relative energy difference) values. Based on these results, a subset of DESs was selected for kinetic testing. Turbidimetric and gravimetric measurements were carried out over time to monitor the dispersion process. The experimental data were then fitted using a simplified Hill-type kinetic model, which successfully described the nonlinear, saturation-limited behavior observed in the systems. DES 8, composed of dodecanoic and decanoic acids, showed the highest dispersion capacity, while DES 6 (tymol and L-(−)- menthol) exhibited moderate performance. DES 12, containing choline chloride and diglycolic acid, showed negligible activity. The findings highlight the relevance of combining solubility theory with kinetic modeling to evaluate hNADES performance. The proposed approach offers a useful tool for predicting and optimizing dispersion processes in structured, low-toxicity solvents.