Molecular Dynamics Simulation of Diffusion of Vitamin C in Water Solution

Abstract

Under different temperatures and concentrations, the diffusion of Vitamin C (VC) in water solution was examined by molecular dynamics simulation. The diffusion coefficients were calculated based on the Einstein equation. The influences of temperature, concentration, and simulation time on the diffusion coefficient were discussed. The results showed that at higher temperature and lower concentration the normal diffusions appear relatively late, but the linear range of mean square displacement curves continues longer than that at lower temperature and higher concentration. At the same temperature, the normal diffusion time increases and the diffusion coefficient decreases as the simulation concentration increases. These simulation results are in good agreement with experiments. Analyses of the pair correlation functions of the simulation systems showed that hydrogen bonds are mainly formed between the hydrogen atoms of VC molecules and oxygen atoms of H 2 O molecules, rather than between the O atoms of VC molecules and H atoms of H 2 O molecules. The diffusion coefficient is higher as the interaction between water molecules and VC molecules is stronger when VC concentration is lower.

Pivotal Role of Heteroatoms in Improving the Corrosion Inhibition Ability of Thiourea Derivatives

“… 36 , 37 In contrast, this length value is greater than 3.5 Å, and van der Waals force is considered as the main interaction of the adsorption. 38 The shortest distances between C, N, and S atoms of DPTU molecules and the surface of Fe(110) are of 2.9 Å; 2.9 Å; and 4.2 Å, respectively. In addition, the corresponding distances with regard to the PPTU molecule are 2.4, 2.3, and 2.7 Å.…”

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