Purdue University School of Chemical Engineering Graduate seminar series Prof. Elias Franses School of Chemical Engineering Purdue University "Stability of Dispersions of Colloidal Particles Against Agglomeration and Sedimentation: Science and Applications" April 21, 2015 9:00-10:15 a.m. FRNY G140 Reception at 8:30 a.m. in Henson Atrium Abstract: A key theme of my career has been how surfactants aggregate in solution and affect various phenomena at oil/water, air/water, and solid/liquid interfaces. These phenomena have important applications in enhanced oil recovery, production of natural gas, and the stabilization of lungs alveoli (air sacs used in breathing) against collapse. Surfactants are also used extensively as dispersants, for improving the stability of dispersed colloidal particles and nanoparticles against agglomeration, as is needed for stable emulsions, foams, and paints. Such stability is also important for low-viscosity inks used in inkjet printers. Even when nanoparticles of high-density materials are stable against agglomeration, they still tend to settle. This settling should be avoided without compromising the product quality. I will describe in some detail how surfactants affect the colloidal dispersion stability of inks and other dispersions. Then I will describe how a lifelong interest in studying surfactant properties has led to a recent important discovery on how to keep dispersions of high-density colloidal particles stable against both agglomeration and sedimentation. Bio: Professor Franses has been at Purdue since 1979, with a one-year absence as a program director at the National Science Foundation in 1990-1991. He has published about 130 papers in refereed journals and several more in refereed books. He has mentored about 25 Ph. D. students, and many undergraduate research participants. In this research he has collaborated substantially with Professors Caruthers, Wang, and Corti. He was an editor of the Journal Colloids and Surfaces, and a member of the editorial board of the Journal of Colloid and Interface Science. He has taught Thermodynamics, Colloidal and Interfacial Phenomena, Unit Operations Laboratory, Reaction Engineering, and several other subjects to hundreds of graduate students and thousands of undergraduate students. In 2014 he published an undergraduate textbook on Thermodynamics with Chemical Engineering Applications.