Behavior of Dissociated Salts in Aqueous Solution: Insights From T₂ Relaxation Time and Signal Intensity Using a...

Area of Science:

• Physical Chemistry
• Food Science
• Materials Science

Background:

• Salts are integral to the food industry, influencing water properties.
• Understanding ionic solute effects on water dynamics is crucial for food processing and preservation.
• Low-field nuclear magnetic resonance (LF-NMR) is a valuable tool for probing water structure and dynamics.

Purpose of the Study:

• To investigate the impact of common food industry salts (NaCl, KCl, CaCl2, MgCl2) on aqueous solutions.
• To explore the relationship between salt concentration, ion type, and water's transverse (T2) relaxation times.
• To analyze the influence of salt properties like kosmotropic and chaotropic behavior on water dynamics.

Main Methods:

• Utilized transverse (T2) relaxometry via low-field nuclear magnetic resonance (LF-NMR).
• Examined aqueous solutions with varying concentrations of NaCl, KCl, CaCl2, and MgCl2 (0 to 0.1079 mol/mol).
• Measured electrical conductivity (EC), water activity, and enthalpy of solution for comprehensive analysis.

Main Results:

• T2 relaxation times were significantly influenced by salt type and concentration.
• Divalent salts (MgCl2, CaCl2) showed distinct effects compared to monovalent salts (NaCl, KCl).
• Mg2+ ions resulted in the shortest T2 relaxation times due to high charge density and hydration.

Conclusions:

• Ionic solutes, particularly divalent cations, profoundly alter water dynamics and T2 relaxation times.
• Observed exponential decay in peak area suggests changes in water structural arrangement and ion-water interactions.
• Findings enhance understanding of salt-water interactions, crucial for food science and material applications.