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RISS 인기검색어
- 검색키워드
- 저자 : Morshed Mahmud (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
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Approaching Hydration Boundary on Ion Transport and Separation through Nanoporous Graphene Membrane
Morshed Mahmud,BoHung Kim 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.6
Due to the polarization of water molecules, the hydration sphere around a single ion increases the effective size of the ion. This phenomenon is called a steric effect that plays a key role in ion transport and separation through a nanopore. Using molecular dynamics (MD) simulation, this transport mechanism of ions through a nanoporous graphene membrane (NPGM) has been analyzed. To induce the water flowrate and ion transport, a pressure-driven flow is generated using specular reflection wall movement at a constant speed for both reservoirs. MD simulations were performed for four different pore sizes to see the scale effect on ion transport. It was observed that ion transportation is proportional to the pore boundary increment due to the shifting of the hydration boundary around a single ion. To investigate this incident, we defined different boundary positions of the hydration layer around a single ion based on the ion water distance. Since the ion transport and separation through the nanopore is very sensitive to the small change in pore diameter, t he exact boundary of pore diameter also needs to be defined. In this consequence, we defined different pore boundaries and predicted the approximate pore boundary of the nanopore based on the Sampson flow equation as a comparison with MD measured data. In the end, after compared with the approximate pore boundary, we establish a maximum hydration boundary of ion that approaches the nanopore concerning the hydration energy in each layer.
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Morshed Mahmud,김보흥 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2
The electrostatic attraction between ions and water is the primary reason for the change in ion bare diameter, which plays a crucial role in saltwater transportation. This study utilizes molecular dynamics (MD) to analyze saltwater transport through a nanoporous graphene membrane by pressure-driven flow. In this work, we describe the impact of pore diameter atomic boundary position on single-ion transportation and signify the steric effect of ions on the water mass flow rate and velocity profile. Due to hydration layer formation, ions hinder the water molecules from their regular velocity, which also decreases the flow rate of water molecules. Interestingly, a significant deviation for different atomic boundary positions is observed for ion rejection for pore diameters less than 1 nm. However, for larger pore diameters, the ion rejection closely matches the atomic boundary position specified by a 2 % water density drop inside the nanopore.
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