Trifkovic Research Group

We are a young University of Calgary research group, under the direction of Professor Milana Trifkovic, in the Department of Chemical and Petroleum Engineering. Our research investigates material design and operation and control of complex, non-linear engineering systems. We seek solutions to these problems through a combination of theoretical and experimental research that enable transforming promising lab concepts into concrete solutions to pressing problems in energy sector. The group has a focus on the design and characterization of novel materials with applications in the energy sector. Examples of these materials include polymer nanocomposites, nanoparticle stabilized emulsions, and bicontinuous interfacially jammed emulsion gels (BIJELS). We have the tools and experience to perform advanced characterization on these materials including the use of a novel “confocal rheology” setup, photonic force microscopy, and an advanced setup that employs fluorescence microscopy to capture 3D images in real time. Another area of interest in the treatment of oil sands tailings, particularly focused on the effect additives can have on the flocculation process and how they can used to enhance the dewatering process. We are also interested in the optimal control of sustainable microgrids and their integration in to the conventional energy sector. Our diverse team allows for many perspectives and approaches to solving not only these challenging problems, but many others as well.

Design of Advanced Materials                                   Complex Fluids

Energy System Control and Optimization                  Enhanced Oil Recovery

Paper published in Langmuir

The significance of graphene oxide-polyacrylamide interactions on the stability and microstructure of oil-in-water emulsions

Jahandideh, H.; Ganjeh-Anzabi, P.; Bryant, S.; Trifkovic, M. Langmuir, 2018.

The emulsification of oil in water by nanoparticles can be facilitated by the addition of costabilizers, such as polymers and surfactants. The enhanced properties of the resulting emulsions are usually attributed to nanoparticle/costabilizer synergy; however, the mechanism of this synergistic effect and its impacts on emulsion stability and microstructure remain unclear. Here, we study the synergistic interaction of graphene oxide (GO) and a high molecular weight anionic polyacrylamide (PAM) in stabilization of paraffin oil/water emulsion systems. We show that the addition of PAM reduces the amount of GO required to stabilize an emulsion significantly. In order to probe the synergistic effect of GO and PAM, we analytically analyze the oil-free GO and GO–PAM dispersions and directly image their morphology via Cryo-TEM and atomic force microscopy (AFM). X-ray diffraction results confirm the adsorption of PAM molecules onto GO sheets resulting in the formation of ultimate GO–PAM complexes. The adsorption phenomenon is a consequence of hydrogen bonding and acid–base interactions, conceivably leading to a resilient electron-donor–acceptor complex. The microstructure of emulsions is captured with two-color fluorescent microscopy and Cryo-TEM. The acquired images display the localization of GO–PAM complexes at the interface while large amount of GO–PAM flocs coexist at the interface and in between oil droplets. Localization of such complexes and flocs at the interface is found to be responsible for their slow creaming rates compared to their GO counterparts. Mechanical properties of both dispersions and emulsions are studied by shear rheology. Rheological measurements confirm that GO–PAM complexes have a higher desorption energy from the interface resulting in higher critical shear strain of GO–PAM emulsions. The results, with insights into both structure and rheology, form a foundational understanding for integration of other polymers and nanoparticles in emulsion systems, which enables efficient design of these systems for an application of interest.

Paper published in the Journal of Colloid and Interface Science

Role of interparticle interactions on microstructural and rheological properties of cellulose nanocrystal stabilized emulsions.

Pandey, A.; Derakshandeh, M.; Kedzior, S.; Shomrat, N.; Segal-Peretz, T.; Bryant. S.;, Trifkovic, M. Journal of Colloid and Interface Science, 2018

Hypothesis
Microstructural and rheological properties of particle-stabilized emulsions are highly influenced by the nanoparticle properties such as size and surface charge. Surface charge of colloidal particles not only influences the interfacial adsorption but also the interparticle network formed by the non-adsorbed particles in the continuous phase.
Experiments
We have studied oil-in-water emulsions stabilized by cellulose nanocrystals (CNCs) with two different degrees of surface charge. Surface charge was varied by means of acidic or basic desulfation. Confocal microscopy coupled with rheology as well as cryogenic scanning electron microscopy were employed to establish a precise link between the microstructure and rheological behavior of the emulsions.
Findings
CNCs desulfated with hydrochloric acid (a-CNCs) were highly aggregated in water and shown to adsorb faster to the oil-water interface, yielding emulsions with smaller droplet sizes and a thicker CNC interfacial layer. CNCs desulfated using sodium hydroxide (b-CNCs) stabilized larger emulsion droplets and had a higher amount of non-adsorbed CNCs in the water phase. Rheological measurements showed that emulsions stabilized by a-CNCs formed a stronger network than for b-CNC stabilized emulsions due to increased van der Waals and H-bonding interactions that were not impeded by electrostatic repulsion.

Paper published in the AIChE journal

Real-time multivariable model predictive control for steam-assisted gravity drainage

Purkayastha, S.; Gates, I.; and Trifkovic, M. AIChE Journal. 2018.

© 2018 American Institute of Chemical Engineers. Thermal recovery techniques, such as steam-assisted gravity drainage (SAGD), are used to recover the majority of the crude bitumen, in Western Canada. However, suboptimal production techniques have led to a large carbon footprint and a subsequent search for more efficient extraction techniques, than open loop manual control. This article summarizes research on the comparison of performance of a novel multi-input multioutput (MIMO) model predictive controller (MPC) with steam trap and oil rate controls with a multi-input single output (MISO) MPC with only steam trap control. An appropriate system identification technique was also used for periodic model update in compliance with changing system behavior. The real-time control study was made possible by establishing a bidirectional communication between computer modeling group STARS TM (virtual reservoir) and MATLAB (onsite controller) software. The results show a 171% improvement in oil recovery for the novel MIMO MPC over the MISO MPC.

Paper published in Soft Matter

Analysis of network formation and long-term stability in silica nanoparticle stabilized emulsions.

Derakhshandeh, M.; Pilapil, B.; Workman, B.; Trifkovic, M.; and Bryant, S. Soft Matter, 14(21). 2018.

© 2018 The Royal Society of Chemistry. Emulsions are widely used in industrial applications, including in food sciences, cosmetics, and enhanced oil recovery. For these industries, an in depth understanding of the stability and rheological properties of emulsions under both static and dynamic conditions is vital to their successful application. Presented here is a thorough assessment of a model nanoparticle (NP) stabilized dodecane-in-water emulsion as a route to improved understanding of the relationship between NP properties, microstructure and droplet-droplet interactions on the stability and rheological properties of emulsions. Emulsions are obtained here with low NP loadings without the need for added electrolyte through the use of an optimized silica NP (SNP) surface modification procedure. The prepared emulsions were characterized via optical microscopy, cryo-scanning electron microscopy (cryo-SEM), zeta potential analysis and laser scanning confocal microscopy (LSCM), enabling quantification of the emulsion droplet size, SNP interfacial coverage/morphology and surface charge. The correlation of these properties with the rheology of the emulsions is investigated through small amplitude oscillatory shear experiments which provide significant insight into the origins of the emulsions' rheological behavior and their stability. In addition, long-term stability, droplet-droplet network formation and microstructural evolution are found to be readily detectable shortly after preparation through measured progression of the emulsion's rheological properties.


Department of Chemical and Petroleum Engineering
Schulich School of Engineering 
University of Calgary 
2500 University Drive N.W. 
Calgary, Alberta 
CANADA T2N 1N4