Colloidal processing, including particle suspensions, foams and emulsions
Wetting, spreading and adhesion of liquids Containing nanoparticles on solids
Thin liquid films
Interfacial and film rheology
Professor Wasan has research interests in the areas of interfacial and colloidal phenomena, foams, emulsions and dispersions, and food and environmental technologies. His present research activities in these areas are:
Thin Liquid Films, Foams, Emulsions and Nano-particle Suspensions
Stability of thin liquid films containing surfactants, proteins, polymer latexes, or nano-particles is being investigated using reflected light microinterferometric techniques. These experiments have revealed for the first time the formation of "ordered" microstructures inside the film over distances of the order of one thousand Angstroms. This microstructure within the film is shown to provide a new mechanism for stabilizing dispersed phase systems. Monte Carlo and Molecular Dynamic simulations are conducted to verify the experimental observations. Important technological factors affecting the ordered microstructure formation and stability of colloidal dispersions such as foam, and emulsion and colloidal suspensions using nanoparticles are being investigated. The National Science Foundation, which is funding his research, awarded Dr. Wasan a special creativity award for this work and he was elected to the National Academy of Engineering, the highest professional honor for engineers, for his research accomplishments.
Wetting, Spreading and Adhesion of Nanofluids on Solid Surfaces
Mechanisms of wetting, spreading and adhesion of fluids containing nanoparticles such as surfactant micelles, proteins and macromolecules are found to be different than those from wetting of normal fluids. A new mechanism of detergency involving nanoparticles structuring phenomena is being investigated. This research has applications in cleaning of hard surfaces such as silicon wafers and soil remediation as well as in adhesion of living cells on solid surfaces and fabrication of nanostructured materials such as photonic crystals. This research was highlighted in his paper published in the journal Nature in 2003.
Film Rheology and its Applications
This research program involves the development and use of a novel experimental technique called film rheometry to measure both the dynamic film tension and film elasticity of surfactant, proteins and polymeric systems. Applications of these properties can be used to control dispersed phase systems such as polymer emulsion stabilization, coalescence of water-in-oil emulsions, foam stability, antifoaming, and thinning of films between bubbles or drops.
Environmental research is conducted on the remediation of high-level and low-level nuclear wastes, which will be immobilized into glass. Major inorganic and organic chemicals in these wastes can cause foaming and gas entrainment problems that ultimately result in excessive shutdown and loss of attainment. The specific aim of this research, which is supported by the U.S. Department of Energy, is to develop a fundamental understanding of the physicochemical mechanisms that produce foaming and air-entrainment in the radioactive waste separation as immobilization process and to develop and test advanced antifoam/defoamimg rheology modifier agents.
Many food formulations including beverages such as beer, cappuccino and milk coffee employ protein stabilized foams and emulsions. Our research in food colloids is directed towards using experimental techniques already available in our laboratory to study the foam and emulsion quality and stability under various conditions in a variety of food dispersions. This work is supported by a number of industrial organizations.
American Institute of Chemical Engineers (AIChE)
- Elsevier Lifetime Achievement Award of Particle Technology Forum (2016)
- Alpha Chi Sigma Award for chemical engineering research (2005)
American Chemical Society (ACS)
- ACS Fellow, elected for introducing a novel stabilization mechanism in colloid science (2016)
- National Award in Colloidal and Surface Chemistry for pioneering theoretical and experimental investigations on the liquid interface in dispersed systems, especially his introduction of a novel colloidal stabilization mechanism for macro-dispersions and for his ingenious translation of fundamental results to full-scale technology (2000)
- Journal of Colloid and Interface Science – Darsh Wasan Award, The Elsevier Company, publisher of the Journal of Colloid and Interface Science (JCIS), in 2015 established the JCIS Darsh Wasan Award, given annually for outstanding contributions to surface and colloid chemistry. (2015)
- University of Illinois, College of Liberal Arts and Sciences Alumni Achievement Award (2015)
- Institute for Food Safety and Health (IFSH) and the FDA – The Darsh Wasan Food Safety Award: Center for Safety and Applied Nutrition (CFSAN) – Established this award in 2013 for Outstanding Contributions to Food Safety across Government, Academia and Industry (2013)
- U.S. National Academy of Engineering, Elected member for his pioneering research, inspirational teaching, and novel technology development in colloidal processing and interfacial rheology (2004)
“Interfacial Transport Processes and Rheology,” (textbook with D. Edwards and H. Brenner), Butterworth-Heinemann - publisher, 558 pages, Boston, MA (1991).
(last 5 years)
"Capillary Rise: Validity of the Dynamic Contact Angle Models," Wu, Pingkeng; Nikolov, Alex; Wasan, Darsh; Langmuir, (Accepted 2017).
“Structural Disjoining Pressure Induced Solid Particle Removal from Solid Substrates Using Nanofluids,” Lim, Sangwook; and Wasan, Darsh; J. Coll. Interface Sci. 500, 96-104 (2017)
“Capillary Dynamics Driven by Molecular Self-layering,” Wu, Pingkeng; Nikolov, Alex; and Wasan, Darsh; Adv Colloid Interface Sci. 243,pp 114-120 (2017).
“Step-wise velocity of an air bubble rising in a vertical tube filled with Nanofluid,” Cho, Heon Ki; Nikolov, Alex; and Wasan, Darsh; Langmuir,33, pp 2920-2928 (2017).
“Escherichia Coli Removal from Model Substrates: Underlying Mechanism Based on Nanofluid Structural Forces,” Shim, Ji-Young; Nikolov, Alex; and Wasan, Darsh; J. Coll. Interface Sci. 498, 112-122 (2017)
“Stepwise thinning dynamics of a foam film formed from an anionic micellar solution - Formation of crown lenses,” Lee, Jongju; Nikolov, Alex; and Wasan, Darsh; J. Coll. Interface Sci. 496, 60-65 (2017).
“Stepwise thinning dynamics of a foam film formed from an anionic micellar solution,” Lee, Jongju; Nikolov, Alex; and Wasan, Darsh; J. Coll. Interface Sci. 487, 217-222 (2017).
“Oil Lenses on the Air-Water Surface and the Validity of Neumann’s Rule”, Nikolov, Alex; and Wasan, Darsh; Adv Colloid Interface Sci. 244, pp 174-183 (2017).
”Experimental study of nanofluid for Enhanced Oil Recovery in Fractured porous media,” Zhang, Hua; Ramakrishnan, T.S.; Nikolov, Alex; and Wasan, Darsh. Journal of Petroleum Science and Engineering.(Submitted 2016)
“The Dynamic Spreading of Nanofluids on Solid Surfaces--Role of the Nanofilm Structural Disjoining Pressure”, Lim, Sandwook; Wu, Pingkeng; Zhang, Hua; Nikolov, Alex; and Wasan, Darsh; J. Coll. Interface Sci. 470, 22-30 (2016).
“Enhanced Oil Recovery (EOR) Driven by Nanofilm Structural Disjoining Pressure: Flooding Experiments and Microvisualization”, Zhang, Hua; Ramakrisnan, T.S.; Nikolov, Alex; and Wasan, Darsh. Energy & Fuels.30 (14) pp 2771-2779 (2016).
“Stratification of a foam film formed from a nonionic micellar solution: Experiments and Modelling.” Jongju Lee; Nikolov, Alex; and Wasan, Darsh. Langmuir. 32 (19), pp 4837-4847 (2016).
“The Dynamics of the Annular Liquid Layer Inside a Capillary”, Zhang, Hua; Feng, Jianyuan; Nikolov, Alex; and Wasan, Darsh; Physics of Fluids 28, 024107 (2016).
“Rise of the Main Meniscus in Rectangular Capillaries: Experiments and Modeling”, Wu, Pingkeng; Zhang, Hua; Nikolov, Alex; and Wasan, Darsh; J. Coll. Interface Sci. 461, 195-202 (2016).
“Nanofluids Alter the Surface Wettability of Solids" Lim, Sangwook; Horiuchi, Hiroki; Nikolov, Alex; Wasan, Darsh. Langmuir. 31 (21), pp 5827-5835 (2015).
“Current Opinion in Superspreading Mechanisms” Nikolov, Alex; Wasan, Darsh. Advances in Colloid and Interface Science, 222, pp 517-529 (2015).
“Effects of Micellar Structuring and Solubilized Oil on the Kinetic Stability of Aqueous Foams”, Lee, Jongju; Nikolov, Alex; Wasan, Darsh; I&EC Res. 53 (49), 18891-18899 (2014).
“Surfactant Micelles Containing Solubilized Oil Decrease Foam Film Thickness Stability” Lee, Jongju; Nikolov, Alex; Wasan, Darsh; J. Coll. Interface Sci. 415, 18-25 (2014).
“Dewetting Film Dynamics inside a Capillary Using a Nanofluid”, Zhang, Hua; Nikolov, Alex; Wasan, Darsh. Langmuir. 30 (31), pp 9430-9435 (2014).
“Foam Stability: The Importance of Film Size and the Micellar Structuring Phenomenon”, Lee, Jongju; Nikolov, Alex; Wasan, Darsh. The Canadian Journal of Chemical Engineering 92 (12), 2039-2045 (2014).
“EOR Using Nanoparticle Dispersions: Underlying Mechanism and Imbibition Experiments”, Zhang, Hua; Nikolov, Alex; and Wasan, Darsh. Energy & Fuels, 28 (5), pp 3002-3009 (2014)
“Wetting-Dewetting Films: The Role of Structural Forces”, Nikolov, Alex; Wasan, Darsh. Advances in Colloid and Interface Science, 206, pp 207-221 (2014).
“Cleaning Dynamics of Oily Soil Using Nanofluids”, Wu, Stanley; Nikolov, Alex; Wasan, Darsh. J. Coll. Interface Sci. 396, 293-306, (2013).
“Stability of Aqueous Foams Containing Dispersed Oil: Importance of Dispersed vs. Solubilized Oil”, Lee, Jongju; Nikolov, Alex; Wasan, Darsh. I&EC Res. 52 (1), 66−72 (2013).
“Dynamic Spreading of Nanofluids on Solids Part II: Modeling”, Liu, Kuan-Liang, Kondiparty, Kirtiprakash, Nikolov, Alex D., and Wasan, Darsh. Langmuir, 28(47), 16274-16284, (2012).
“Dynamic Spreading of Nanofluids on Solids Part I: Experimental”, Kondiparty, Kirtiprakash, Nikolov, A.D.; Wasan, Darsh; and Liu, Kuan-Liang.Langmuir 28, 14618-14623, (2012).
“Calculation of the Surface Potential and Surface Charge Density by Measurement of the Three-Phase Contact Angle”, Horiuchi, Hiroki; Nikolov, Alex; Wasan, Darsh. J. Coll. Interface Sci. 385, 218-224 (2012).