Department of Chemical and Biomolecular Engineering
Chemical Engineering Sciences
Chemical engineering as a distinct discipline, now more than a century old, has evolved from industrial chemistry and empiricism into a mature field that combines the understanding and predictive capabilities of fundamental physical sciences with the final goal of design and control of industrial scale applications. Research in Chemical Engineering Sciences in the Department covers most of the classical topics, such as thermodynamics, reaction engineering and catalysis, transport phenomena, separation processes and colloidal and interfacial phenomena, often with a modern twist. Many of the activities in Chemical Engineering Sciences also provide the foundation for other thrusts described here. The Department interacts closely, through research activities and faculty joint appointments, with the Institute of Chemical and Engineering Science (a national Research Institute) funded by the Agency for Science, Technology and Research (A*STAR) of Singapore.
Examples of activities in this Thrust include, but are not limited to,
- Chemical Thermodynamics
- Activities in chemical thermodynamics have evolved from classical macroscopic phase and reaction equilibrium studies to understanding behavior at the molecular level using statistical thermodynamics. Accordingly, recent efforts in this area are targeted at microscopic ensembles. Such ensembles are found in macromolecular and colloidal systems. Current interests are in protein crystallization and bioreactions under confinement, and solid-state nanomaterials for separation, storage and catalysis. On the classical side, nucleation and crystallization theories and controlled experiments are used to understand deliquescence and efflorescence of aerosol as an atmospheric pollutant.
- Reaction Engineering
- Current chemical reaction engineering research in the Department is focused on detailed kinetic, mechanistic and electrochemical studies, microreactor technology for chemical and nanomaterials synthesis, and novel configuration, control and optimization of industrial reactor systems. Among the significant activities in heterogeneous catalysis are ab-initio mechanistic studies for hydrocarbon reactions, and asymmetric reactions for chiral fine chemicals and pharmaceutical intermediates. The microreactor research encompasses both single-phase and multi-phase chemical reactions yielding products ranging in size from small molecules to colloidal particles. Investigation in this area also includes non-linear dynamics of droplet and bubble flows in microchannels. The electrochemical study of reactions in fuel cells, combined with modeling of associated transport processes, is targeted at improving the design and performance in order to compete with traditional power sources.
- Separation Processes
- Separation processes constitute major operations in the chemical, biochemical and pharmaceutical process industries. Research in this area consists of both fundamental and applied studies, spanning both mechanical and diffusional separation processes. Mechanical separations include cake and deep-bed filtration for solid-liquid separations as well as separation of biomolecules and chiral compounds using surface functionlized magnetic nanoparticles. On the other hand, diffusional processes include asymmetric and composite membranes for gas separation, nanofiltration and pervaporation for biopharmaceutical separation and purification, liquid membranes for metal extraction and separation of bio-products. In addition, diffusional processes include adsorption for gas separation, hydrocarbon and metal adsorption from waste streams using organic, inorganic and microbial adsorbents, and protein separation. The primary focus in gas membrane development is on the science linking synthesis conditions to morphology and performance. The scope of adsorption studies for separation ranges from fundamental studies in equilibrium, kinetics and column dynamics to the development and simulation of industrially relevant processes. Specific process interests include gas separation by pressure swing adsorption, and coupled reaction and separation in simulated moving beds.
- Colloids, Interfaces and Complex Fluids
- Colloidal and interfacial phenomena are important both in industrial processes and in consumer applications. Common day-to-day consumer items, such as numerous pharmaceutical and health care products, some food products and beverages, colorants and paints, etc., are colloidal dispersions. Colloidal dispersions are part of a class of materials that are known as complex fluids. Notable examples include liquid-crystalline materials, polymer solutions and gels, surfactant assemblies, and biological materials. The practical significance of the interaction between the structural (thermodynamic), mechanical and fluid dynamic aspects of complex fluids extends beyond their implications to conventional colloids. Understanding the stability of these suspensions often determines their shelf-life and is required for quality control. The research in complex fluids includes experimental, computational and theoretical rheological studies focused on constructing a link between the microstructure and macroscopic properties of complex fluids. On-going investigations include electroviscous effects and clustering of polyelectrolytes, phase behavior and rheology of surfactant-polymer mixtures, tracer diffusion in gels, and interaction between nanoparticles and vesicles. As the above description illustrates, the activities in Chemical Engineering Sciences are designed to provide the crucial underlying foundation that binds research activities in materials and devices, systems engineering and biomolecular sciences in the Department.
- Transport Phenomena
- Study of transport phenomena is another important foundation on which the field of chemical engineering sciences rests. It finds its mathematical origin in the constitutive equations that define the conservation of material, energy and momentum in a continuum mechanics setting. Activities in this field extend over liquid-solid, gas-solid, gas-liquid, and gas-liquid-solid systems. Fundamental investigations of thin film polymerization, crystallization kinetics, surface energy evolution and thermal stability of liquid-crystalline polymers are being conducted. These will find use in high-performance electronic display devices, among other applications. Continuum models developed for studying rheological behavior of granular materials are giving insight into instabilities associated with granular flow. Computational fluid dynamics (CFD) simulations of transport of granular materials are revealing interesting results that are difficult to obtain by other means. Modeling and simulation are also in progress to investigate bubble formation at an orifice, hydrodynamics and mass transfer in air-lift reactors, and mixing in circulating systems. The power of CFD modeling has also been extended to develop a general simulation program for targeted treatment of tumors. These CFD studies are complemented by parallel experimental programs. Other notable interests include microfluidics, transport in micropores with applications in separation and catalysis, and transport in drying with applications targeted at food processing.