Molecular insights into aqueous bronopol solutions containing sodium and magnesium ascorbates: A multi-technique acoustic, thermodynamic, and spectroscopic study

This study investigates the molecular interactions in ternary aqueous systems containing Bronopol along with sodium and magnesium ascorbates. Experiments were carried out at four temperatures (288.15, 298.15, 308.15, and 318.15 K) across a range of solute concentrations (0.00, 0.01, 0.03 and 0.05 mol.kg-1). The Anton Paar DSA 5000 M was used to accurately measure density and speed of sound, enabling the calculation of key thermodynamic parameters, including apparent molar volume (Vϕ), partial molar volume (Vϕ0), and partial molar volume of transfer (ΔVϕ0). Apparent molar isentropic compressibility (Kϕ,s), its standard partial molar value (Kϕ,s0), and the transfer function (ΔKϕ,s0) were evaluated to assess solute compressibility within these ternary systems. The structural behavior of the mixtures whether they act as structure-makers or structure-breakers, was examined using Hepler’s thermodynamic approach. Furthermore, bonding interactions between Bronopol and the ascorbate compounds were examined using FTIR analysis conducted over the spectral range of 400–4000 cm⁻¹. The outcomes of this study offer valuable insights into intermolecular interactions that support the development of sustainable, high-performance preservative systems with potential applications in chemical engineering, pharmaceuticals, and cosmetics. The use of bio-based additives, such as sodium and magnesium ascorbate, highlights the potential for more sustainable approaches in formulation science, aligning conceptually with UN 2030 Sustainable Development Goals.