Stability Mechanism of Adsorbed Gas in Gas-Liquid Mixed Layer

doi:10.19596/j.cnki.1001-246x.8293

Abstract

Abstract:

Experimental results show that gas dissolved in water can be adsorbed and accumulated on hydrophobic surface. There are two formations of adsorbed gas, nanobubbles and micro pancakes. Classical theory can't explain their stable existence. In this paper, molecular dynamics simulation was used to study the adsorption and agglomeration of gas. It is found that there exist a gas-liquid mixed layer coated on the adsorbed gas. The shape and characteristics of the mixed layer were studied and analyzed. It was found that the viscosity of gas-liquid mixture was greater than that of water and it inhibits gas diffusion.

Key words: gas adsorption, gas-liquid mixing layer, hydrophobic interface

CLC Number:

O647.31

Qingqun LUO, Jiansu LI. Stability Mechanism of Adsorbed Gas in Gas-Liquid Mixed Layer[J]. Chinese Journal of Computational Physics, 2021, 38(4): 465-469.

Figures/Tables 9

Fig.1 Model of simulation

Table 1 Parameters in simulation

原子	b₀/nm	K_b/(kJ·mol^-1·nm^-2)	ε/(kJ·mol^-1)	σ/nm
N	0.112 0	1 280 025	0.711 280	0.325 000
C	0.142 0	334 720	0.359 824	0.339 967

Fig.2 (a) Isoclines of water density at 300 ns; (b) Isoclines of gas density at 300 ns; (c) Isoclines of gas density at 300 ns obtained from a density matrix (The yellow line is the isocline with 20 gas molecules per nm3.); (d) The points with 20 gas molecules per nm3; (e) Best-fit circular arc of the isocline with 20 gas molecules per nm3

Fig.3 Density distribution of water, gas and system at 40 ps

Fig.4 Gas number density distribution at different simulation times

Fig.5 Curvature of gas surface as a function of time

Fig.6 Distribution of water molecular velocity at 200 ns

Fig.7 Water density distribution at 200 ns

Fig.8 Trajectory of a nitrogen atom in every ten steps from 5.075 ns to 5.095 ns

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