Probing the dehydration dynamics and structural transformation of oxalic acid dihydrate using terahertz spectroscopy
Zhenqi Zhu1, Hui Xu1, Bin Yang2
1Huzhou Key Laboratory of Green Energy Materials and Battery Cascade Utilization, School of Intelligent Manufacturing, Huzhou College, Huzhou, 313000, PR China.
Abstract:
The dehydration of hydrates involves the evolution of molecular structures at different scales. Oxalic acid dihydrate (OAD) serves as a critical model system for studying hydrate dehydration. Here, we employ terahertz (THz) spectroscopy to investigate the temperature- and time-dependent dehydration dynamics of OAD, thereby establishing mechanistic correlations between spectral signatures and structural evolution. Oxalic acid (OA) and OAD exhibit different THz vibration characteristics, a difference attributed to hydrogen bond interactions between crystalline water and OA molecules. At different temperatures, the dehydration products of OAD exhibit regular spectral changes, indicating the gradual dissociation of crystalline water. Furthermore, the dehydration stages at different time scales are revealed, achieving the responses to the intermediate and amorphous states. This work demonstrates the unique advantages of THz spectroscopy in the study of food hydrates, providing new insights into hydration behavior at the molecular level.
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