Volumetric and Ultrasonic Investigation of Glycolic and Malic Acids with Water-Soluble Potassium Benzoate Solutions at Different Temperatures

In this work, a density and sound velocity analyzer was utilized to evaluate the densities and ultrasonic speeds of the ternary liquid combination (water + potassium benzoate + glycolic acid/malic acid) with concentration levels of (0.04, 0.05, 0.06) mol·kg–1 at numerous temperatures. Several volumetric and ultrasonic parameters were computed, including apparent and partial molar characteristics, transfer parameters, expansibilities, temperature-dependent derivative, and the coefficient of thermal expansibility, which were obtained using the measured data. The concept of cosphere overlap has been applied to analyze several interactions occurring inside the liquid system, providing an explanation for the acquired results. The interaction coefficients have been intended to determine the interactions among solutes along with solvents in liquid systems. Fourier transform infrared (FTIR) spectral analysis revealed shifts in the O–H stretching band indicating the existence of hydrogen bonding and other molecular interactions within the studied (potassium benzoate + water) systems. This study not only enhances the understanding of molecular interactions in preservative systems but also provides valuable insights for optimizing formulations in food preservation, pharmaceuticals, and cosmetic industries. The findings can contribute to the development of more effective and stable preservative solutions, improving product quality and shelf life.