Physicochemical investigations of calcium propionate with 1-Ethyl-3-methylimidazolium ethyl sulphate and 1-Butyl-3-methylimidazolium chloride in aqueous systems

Present research work examines the physicochemical interactions of calcium propionate (a widely used food preservative) with two different imidazolium-based ionic liquids (ILs) i.e. 1-Ethyl-3-methylimidazolium ethyl sulphate ([C₂mim][EtSO₄]) and 1-Butyl-3-methylimidazolium chloride ([C₄mim][Cl]) in aqueous systems. Measurements were conducted across three molal concentrations (0.05, 0.10, 0.15 mol kg⁻¹) of the ILs, spanning a temperature range of 293.15 to 313.15 K at p = 0.1 MPa. Viscosity and refractive index measurements were used to probe molecular interactions as a function of temperature and concentration. The resulting data were analyzed to determine key parameters, viscosity coefficients {Falkenhagen coefficient (A), Jones-Dole coefficient (B)}, viscosity B-coefficients of transfer (ΔtrB) and dB/dT values. The obtained data definitively suggest effective solute-cosolute interactions between calcium propionate and the aqueous ionic liquid media. Notably, the positive ΔtrB values indicate that calcium propionate interacts more strongly in the IL-water mixtures than in pure water. Furthermore, the positive dB/dT values inferred a structure-breaking (chaotropic) effect of the media on the solvent structure. These comprehensive physicochemical insights are vital for formulating more effective hybrid preservative systems and advancing the role of these materials in green chemistry applications.