Speaker: Prof. Shaofan Li （University of California-Berkeley）

Chair Person: Prof. Shaoqiang Tang

Date: 21th May, 2018, 09:00-11:00

Place: Room 210, Faculty of Engineering

Report Introduction:

     A scale-up graphene-membrane based centrifuge with a hierarchical multi-scale pore structure designed for reverse osmosis desalination was proposed. We propose a macroscale rotating centrifuge that has micron size pores on the wall of the centrifuge, and nano-scale pores on local graphene membrane patches that cover the micron-size pores so that it can perform desalination task at industrial scale.

     The proposed co-axial membrane centrifuge device has a strong possibility of resolving all three main critical issues for nano-materials based membrane technology in desalination. In specific, it has (1) Scalability, (2) Self-assisted anti-fouling mechanism, and (3) Low energy consumption. A successful fabrication of such nanoporoous centrifuge may potentially revolutionize the membrane desalination technology by providing a fundamental solution to water resource problem.

     In this work, we derived the critical angular velocity that is required for the centrifugal force or pressure to counter-balance osmosis force or pressure, so that the reverse-osmosis (RO) desalination process can proceed. To validate this result, we conducted a large scale (four million atoms) full atom molecular dynamics (MD) simulation to exam the critical angular velocity required for reverse osmosis at nanoscale. It is showed that the analytical result derived based on fluid mechanics and the numerical result observed in MD simulation are consistent and well matched. The main advantage of such nano-material based centrifuge is its intrinsic anti-fouling ability to clear Na⁺ and Cl^- ions accumulated at the vicinity of the pores because of the Coriolis effect. Molecular dynamics modeling and analyses have been conducted to study the relation between osmotic pressure, centrifugal force, and water permeability. It is found that the minimum energy required by the model is at the low end of RO desalination.

About Speaker:

     Dr. Shaofan Li is currently a full professor of applied and computational mechanics at the University of California-Berkeley. Dr. Li graduated from the Department of Mechanical Engineering at the East China University of Science and Technology (Shanghai, China) with a Bachelor Degree of Science in 1982; he also holds Master Degrees of Science from both the Huazhong University of Science and Technology (Wuhan, China) and the University of Florida (Gainesville, FL, USA) in Applied Mechanics and Aerospace Engineering in 1989 and 1993 respectively. In 1997, Dr. Li received a PhD degree in Mechanical Engineering from the Northwestern University (Evanston, IL, USA), and he was also a post-doctoral researcher at the Northwestern University during 1997-2000.

    In 2000, Dr. Li joined the faculty of the Department of Civil and Environmental Engineering at the University of California-Berkeley. Dr. Shaofan Li has also been a visiting Changjiang Professor in the Huazhong University of Science and Technology, Wuhan, China (2007-2013). Dr. Shaofan Li is the recipient of IACM (International Association of Computational Mechanics) Fellow Award [2017]; Distinguished Fellow Award of ICCES [2014]; ICACM Computational Mechanics Award [2013], USACM Fellow Award (2013), A. Richard Newton Research Breakthrough Award [2008], and NSF Career Award [2003]. Dr. Li has published more than140 articles in peer-reviewed scientific journals (SCI) with h-index 42 (Google Scholar), and he is also the author of two research monographs/graduate textbooks.