Start
Apr 04, 2014 - 17:00
End
Apr 04, 2014 - 17:00
Venue
Creativity Hall (Room 118) Chemical Engineering
Event Type
Speaker
Suresh K. Bhatia School of Chemical Engineering The University of Queensland QLD 4072 Australia
Title
How Water Adsorbs in Hydrophobic Nanospaces
Abstract: The understanding of the mechanism of water adsorption in the hydrophobic nanospaces of carbons is critical to many industrial processes for gas separation and water purification and to emerging nanotechnologies for desalination CO2 capture from flue gas and separation by nanofluidic devices. While there have been numerous attempts at simulating water adsorption in hydrophobic carbons using idealized models of independent slit pores only qualitative agreement with experiment has been achieved and the answer to the difficult question of how water enters such spaces has remained elusive. Using grand canonical Monte Carlo (GCMC) simulations with a realistic model of a disordered hydrophobic carbon we show that the key to the puzzle is the connectivity of the structure – overlooked by independent slit pore models. Our simulations and data confirm that significant amount of water adsorbs below the saturation pressure in purely hydrophobic nanopores and it is demonstrated that this occurs only when pore entries are sufficiently large to allow the passage of stable hydrogen-bonded water clusters. We investigate the effect of pore connectivity through synthetic models of connected and unconnected slit pores and show that the connectivity to narrow water-filled pores mediates the adsorption of water in large hydrophobic nanospaces. This unique feature is not observed for nonpolar or weakly polar gases (e.g. Ar or N2) at subcritical conditions and explains why the Kelvin equation fails to estimate the condensation pressure for water. The results open the door for the design and tailoring of efficient adsorbents for CO2 capture in which the co-adsorption of water vapour which saturates flue gas is inhibited.About the speaker: Suresh Bhatia received a B.Tech. degree in chemical Engineering from the Indian Institute of Technology Kanpur and Master’s as well as PhD degrees from the University of Pennsylvania. He worked for a few years in industry in the USA and for two years at the University of Florida before joining the Indian Institute of Technology Mumbai in 1984 and subsequently The University of Queensland in 1996. His main research interests are in adsorption and transport in nanoporous materials and in heterogeneous reaction engineering where he has authored over two hundred scientific papers in leading international journals. He has received numerous awards for his research including the Herdillia Award for Excellence in Basic Research in Chemical Engineering the Shanti Swarup Bhatnagar Prize for Engineering Sciences and in 2009 the ExxonMobil Award for excellence in Chemical Engineering from the Institution of Chemical Engineers. Since January 2010 he holds an Australian Professorial Fellowship from the Australian Research Council. He is a Fellow of two major academies – Australian Academy of Technological Sciences and Engineering and the Indian Academy of Sciences ‑ and of the Institution of Chemical Engineers. He is the Regional Editor of the international journal Molecular Simulation. Between 2007 and 2009 he was the Head of the Division of Chemical Engineering at UQ and was instrumental in its elevation to a School of Chemical Engineering.