The Department of Chemical and Biological Engineering welcomes Alex D. Nikolov, research professor in the Department of Chemical and Biological Engineering at Illinois Institute of Technology, for a lecture titled “DLVO Surface Forcers in Liquid Films and Statistical Mechanics Oscillatory Structural Forces in Dispersion Stability” on Wednesday, November 30, 2022, from 3:15–4:30 p.m. in Room 108 of Perlstein Hall.
This talk focuses on the theory of stability of dispersions considering two models: classical DLVO theory of surface forces, the interactions between two particles consists of two terms: London-van-der-Waals attractive interactions and the electricity repulsive interactions in the frame of the Debye-Heckle theory, electrostatic interaction purely repulsive. The solvent, the aqueous solution of electrolyte, was considered as continuous phase. The film stability criteria: P γ> Π and dP γ/dh>0. The role of film area on stability is not considered. Henderson and Lozada-Cassou (HC) applied statistical mechanics approach to calculate the film free energy to predict dispersion stability by consider the two large hard spherical as a colloidal particle immersed in fluid of decried small particles (solvent). HC apply the radial distribution function g(r) to calculate the free oscillatory structural energy using W(r)=-kTlng(r). Henderson-Cassou (HC) theoretical approach is also applied to the particle collective interactions g(r) in film and explains stability of film of complex fluid e.g., micellar and colloidal dispersions, when the DLVO theory applies phenomenology approach to predict film stabilized with ionic type surfactant at concentration bellow critical micellar concentration with the limitation.
Alex D. Nikolov is a research professor in the Department of Chemical and Biological Engineering at Illinois Institute of Technology. Nikolov studied physical chemistry at Sofia University in Bulgaria. In 1990 he was the recipient of the Bulgarian National Award of Chemistry for the discovery of a new dispersion stability mechanism. He was a visiting scholar at Moscow University in 1975, Danish Technical High School in Lungby in 1976, Unilever Port Sunlight Research Laboratory in 1980, and Stockholm’s Swedish Royal Surface Chemistry Research Institute in 1982. Nikolov has worked on research projects for the National Science Foundation and the U.S. Department of Energy since 1985. In 1994 he began his career at the Illinois Tech as a research professor in the Department of Chemical Engineering. He has published his scientific results in more than 200 papers in peer-reviewed journals and four book chapters, and he holds four U.S. patents. He is on the editorial board of Advances in Colloid and Interface Science.