Programme

P.11 -- Poster, VCTP-44

Date: Tuesday, 30 July 2019

Time: 08:30 - 10:00

Specific Ion Effects on Static and Dynamic Properties of Aqueous Solution Confined between Uniformly Charged Hydrophobic Plates

Hien Nguyen (1), Cuong Quoc Doan (2), Han Tuong Luc (3), Sangmo Kang (4), Yong Kweon Suh (4), Hai Hoang (3*)

(1) Department of Education and Training, University of Khanh Hoa, Nha Trang City, Khanh Hoa Province, Vietnam (2) Quang Binh University, Dong Hoi City, Vietnam (3) Institute of Fundamental and Applied Sciences, Duy Tan University, 10C Tran Nhat Duat Street, District 1, Ho Chi Minh City 700000, Viet Nam 4Department of Mechanical Engineering, Dong-A University, Saha-gu, Busan, 604-714, Korea

Investigation of properties of a aqueous solution confined in nano-pores has one important role not only in the fundamental science, but also in the engineering applications such as the molecular separation or identification processes in the biological and chemical engineering. These properties are strongly affected by various factors, e.g. the confinement gap, the properties of solid wall, ion species etc. In this work, we have developed a FORTRAN molecular dynamics code to study the specific ion effects on the static and dynamic properties of aqueous solution confined in nano-pores that are made of two uniformly charged hydrophobic plates. Two kinds of ion species considered are sodium and chloride ion. The SPC/E model and combination of quaternion coordinates with Euler angles are used to model the water molecules and constraint the structure of water molecules, respectively. The hydrophobic plates are charged uniformly on its inner surface and separated by 2.6 nm. Each of solution consists of 680 water molecules and 20 ions. We employed the modified Ewald summation for the uniformly charged surface following Wen Yang (2006) and the method of PPPM (particle-particle-particle-mesh) to compute long-range interactions. The results show that properties of solution are influenced rather strongly by kind of ion. In particularly, ions and water molecules in the region close to the channel wall is more strongly absorbed on the channel wall for the chloride solution. Otherwise, ions are more hydrated and water molecules are more preferably oriented in the sodium solution. We also compared results obtained the MD simulations with those provided by solving the Poisson-Boltzmann equation Keywords: Molecular dynamics simulation, Aqueous solution, Hydrophobic plate, PPPM methods, Poisson Boltzmann equation

Presenter: Nguyễn Minh Hiền