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Electrochemical science and engineering are at the forefront in many technologies focusing on alternative energy sources (fuel cells, batteries, supercapacitors), pollution control of gaseous (e.g. CO2, NOx) and liquid effluents and environmentally more sustainable chemical process development (e.g. the electrosynthesis alternative to conventional thermochemical processes).
The commercial development of many electrochemical systems, including a variety of fuel cell types and batteries, pollution control and electrosynthesis, is hampered by kinetically sluggish electrode reactions. The mission of our research program is to discover and investigate selective, durable and cost-effective electrocatalysts and to integrate the catalyst structures with the electrode and cell design in order to develop high-performance electrochemical devices and processes. To accomplish our mission we deploy a multi-pronged approach combining fundamental experimental electrochemical and surface science studies of the electrocatalytic activity with theoretical insights into the catalytic activity, development of methods for nanostructured electrocatalyst deposition on electronically conductive 3D substrates and electrochemical cell and reactor engineering advancements.
1. High-performance and cost effective bifunctional catalysts for oxygen reduction/evolution reactions
The oxygen reduction and evolution reactions (ORR, OER) are two of the most important reactions in electrochemistry with myriad of applications. We developed a class of doped/intercalated MnOx catalysts that are suitable for a range of applications such as: alkaline rechargeable metal-air (e.g., Zn-air, Al-air, Li-air) batteries, water electrolysis, regenerative alkaline fuel cells and oxygen depolarized cathodes for electrosynthesis. A company was founded to commercialize these and other catalysts: www.catalystsquare.com.
E. Gyenge, P. Hosseini-Benhangi, ‘An Oxygen Electrode and a Method of Manufacturing the Same’ US Patent App. 2,940,921, 08/30/2016.
P. Hosseini-Benhangi, M.A. Garcia-Contreras, A. Alfantazi, E. Gyenge, ‘Method for Enhancing the Bifunctional Activity and Durability of Oxygen Electrodes with Mixed Oxide Electrocatalysts: Potential Driven Intercalation of Potassium’ Journal of The Electrochemical Society, 162 (12) F1356-F1366 (2015).
2. Graphene electrosynthesis and applications in power sources
Graphene has tremendous potential for applications in alternative energy systems. However, its production is still problematic and some of the common methods involve harsh and aggressive chemicals that are misaligned with its ‘green technology’ image. We developed a ‘green’ method for simultaneous anodic and cathodic electro-exfoliation of graphitic precursors in ionic liquids for production of high-quality and high-concentration graphene micro-flakes. The graphene micro-flakes showed excellent results in microbial fuel cell anodes and as microporous layers in PEM fuel cells.
A.Taheri Najafabadi, E. Gyenge, ‘Synergistic production of graphene microsheets by simultaneous anodic and cathodic electro-exfoliation of graphitic electrodes in aprotic ionic liquid electrolytes’ Carbon 84, 449-459 (2015).
A.Taheri Najafabadi, N. Ng, E. Gyenge, ‘Electrochemically exfoliated graphene anodes with enhanced biocurrent production in single-chamber air-breathing microbial fuel cells ’ Biosensors and Bioelectronics 81, 103-110 (2016).
3. Electro-oxidation of borohydride in aqueous and molten electrolytes, borohydride fuel cells and batteries
Borohydride has the 2nd highest theoretical specific energy density among all fuels after hydrogen. The fuel cell applications of borohydride (e.g. NaBH4) have been intensely investigated by our group. We demonstrated the first mixed reactant borohydride fuel cell using the Swiss-roll cell design, and more recently, we were also the first to investigate the borohydride oxidation in a molten eutectic electrolyte.
A.Aziznia, C. Oloman and E. Gyenge, ‘Experimental advances and preliminary mathematical modeling of the Swiss-roll mixed-reactant direct borohydride fuel cell’ Journal of Power Sources 265, 201-213 (2014).
A.Wang, E. Gyenge, ‘Borohydride electro-oxidation in a molten alkali hydroxide eutectic mixture and a novel borohydride battery’ Journal of Power Sources 282, 169-173 (2015).
4. Electrochemical conversion of CO2 and CO2 redox flow batteries
The CO2 redox flow battery invented by Dr. Gyenge, uses a CO2-based redox couple at the negative electrode coupled with an inexpensive and fast electrode kinetics redox couple at the positive electrode. It is based on bifunctional catalysts and it constitutes a novel option for utilizing CO2 in a carbon-neutral loop of alternative energy storage and generation, while reducing green house gas emissions.
E. Gyenge, ‘Redox Flow battery with Carbon Dioxide Based Redox Couple’ PCT Appl. WO 2017/A004705 A1, 01/12/2017.
Course materials can be accessed by registered students via UBC Connect website.
- Polymer rheology (ionomers and hydrogen bonding polymers)
- Non-linear viscoelasticity (ionomers and hydrogen bonding polymers)
- Rheological characterization
- Polymer processing (extrusion, film blowing, blow molding and coating)
- Polymer processing instabilities (melt fracture)
- Processing aids
- Processing of polyolefins and fluoropolymers
- Paste extrusion of PTFE
- Food rheology (cheese and dough)
- Rheology of biomaterials (nanocrystalline cellulose)
Non-Newtonian fluid mechanics is often distinguished from its Newtonian counterpart by the additional requirement that first a constitutive equation be specified as part of the problem statement and secondly a suitable wall boundary condition other than the no-slip be imposed as a necessary ingredient. It is also accepted that diverse fluids and diverse wall materials lead to diverse interfacial behaviors. Therefore, the main thrust of this part of the research program is both a theoretical and an experimental study of diverse polymer-wall interfaces. The development of relationships that describe the behavior of such interfaces under flow conditions are necessary in order to gain a better understanding of phenomena such as sharkskin, gross melt fracture and stick-slip. The identification of processing aids that can eliminate such phenomena is a key element in these studies.
Polymer flow instabilities and more specifically melt fracture phenomena in polymer processing is of particular importance. Application of interest include extrusion, film blowing, blow molding and coating flows (wire, cable and sheet) of polyolefins, fluoropolymers and other polymers. Methods to enhance the rate of production by eliminating or postponing these phenomena to higher shear rates are also of interest. Processing aids such as fluoroelastomers, stearates and their combination are examined in extrusion and other polymer processing operations in order to evaluate their effectiveness.
The rheology and processing of polymer blends are also of particular interest to the research program of Professor Hatzikiriakos. During the processing of polymer blends, there is a variety of phenomena that may take place. At increasing shear/extensional rates, the polymer blends may phase-separate (shear induced de-mixing) and then at higher rates may mix again (shear induced mixing) or vice versa. These effects are dramatic as the homogeneous region in their (polymer blends) phase diagram may be shifted or enlarged by several degrees under flow conditions. This part of the research program focuses on the rheological and thermodynamic behavior of polymer blends under flow (shear/extensional) conditions. The phase behavior of model as well of industrial importance polymer blends is studied both experimentally and theoretically. The results from these fundamental studies are used in order to gain a better understanding on the resulting morphology during processing and its effects on the mechanical properties of final products.
Another aspect of the research program in polymer rheology is the development of new techniques to measure the nonlinear rheological viscoelastic properties of molten polymers such as polyolefins, ionomers and hydrogen bonding polymers. The key element of this part of the program is to use the rheological properties measured in the laboratory in order to gain a better understanding of the behavior of polymeric systems in a melt processing operation such as film blowing, film extrusion, film casting, blow molding and coating flows (wire, cable and sheet). Complex fluids, semisolids and solids are of particular importance as well i.e. polymer blends, polyelectrolyte hydrogels (based on nanocrystalline cellulose), cheese, dough, and biomaterials such as nanocrystalline based materials.
The research interests/efforts of Professor Hatzikiriakos include an integrated study of the paste extrusion process of polytetrafluoroethylene (PTFE) and other polymers (UHMWPE, PEEK), metals and metal oxides. Relevant tests for the rheological characterization of complex materials such as PTFE paste is of primary interest. Other areas of interest include experimental and computational studies of polymer processing operations such as film blowing, film casting, pipe extrusion, profile extrusion, blow molding, thermoforming and embossing.
Professor Hatzikiriakos and his students have published over 240 papers. He has edited a book entitled Polymer Processing Instabilities: Understanding and Control (Marcel Dekker). His group is actively collaborating with the University of Crete and the National Technical University of Athens. Professor Hatzikiriakos also serves as an expert witness in polymer patent litigation and dispute and as a consulting engineer to the polymer industry.
T. Tomkovic, E. Mitsoulis and S.G. Hatzikiriakos, “Contraction Flow of Ionomers and their Corresponding Copolymers: Ionic and Hydrogen Bonding Effects,” Physics of Fluids, 31, 033102 (2019)
T. Wright, T. Tomkovic, S.G. Hatzikiriakos, and M.O. Wolf, “Photoactivated Healable Vitrimeric Copolymers,” Macromolecules, 52, 36-42 (2019)
S. Arola, M. Ansari, A. Oksanen, E. Retulainen, S.G. Hatzikiriakos, and H. Brumer, ”The Sol-Gel Transition of Ultra-low Solid Content TEMPO-Cellulose Nanofibril/Mixed-linkage b-glucan Biocomposite Gels,” Soft Matter, 14, 9393-9401 (2018)
T. Tomkovic and S.G. Hatzikiriakos, “Nonlinear Rheology of Poly(ethylene-co-methacrylic acid) Ionomers,” J. Rheology, 62, 1319-1329 (2018)
V. Triandafilidi, S.G. Hatzikiriakos, J Rottler, “Molecular simulations of the piezoionic effect,” Soft Matter, 14, 6222-6229 (2018)
T. Tomkovic, E. Mitsoulis and S.G. Hatzikiriakos, “Contraction Flow of Ionomers,” J. Non-Newtonain Fluid Mech., 262, 131-141 (2018)
M. Ebrahimi, V.K. Konagandi and S.G. Hatzikiriakos, “Dynamic Slip of Polydisperse Linear Polymers using Partitioned Plate,” Physics of Fluids, 30, 030601 (2018)
Anna-Lena Oechsle, Lev Lewis, W.Y. Hamad, S.G. Hatzikiriakos, M.J. MacLachlan,”CO2-Switchable Cellulose Nanocrystal Hydrogels,” Chemistry of Materials, 30, 376-385 (2018)
G. Natale, C. Datt, S.G. Hatzikiriakos, G.J. Elfring,” Autophoretic locomotion in weakly viscoelastic fluids at finite Péclet number,” Physics of Fluids, 29, 123102 (2017)
Love-Ese Chile, P. Mehrkhodavandi, S.G. Hatzikiriakos, “Aromatic interactions in aryl-capped polylactides: A thermorheological investigation,” J. Rheology, 61, 1137-1148 (2017)
C. Datt, G. Natale, S.G. Hatzikiriakos, G.J. Elfring,”An active particle in a complex fluid,” J. Fluid Mech., 823, 675-688 (2017)
E. Chatzigiannakis, M. Ebrahimi, and S.G. Hatzikiriakos, “On the molecular weight dependence of slip velocity of polymer melts,” J. Rheology, 61, 731-738 (2017)
T. Ebrahimi, H. Taghipour, D. Grießl, P. Mehrkhodavandi, S.G. Hatzikiriakos and E. van Ruymbeke “Binary Blends of Entangled Star and Linear poly(hydroxybutyrate): Effect of Constraint Release and Dynamic Tube Dilation,” Macromolecules, 50, 2535-2546 (2017)
M. Ebrahimi, V.K. Konaganti, S. Moradi, A.K. Doufas, and S.G. Hatzikiriakos, “Slip of Polymer Melts over Micro/Nano-patterned Surfaces,” Soft Matter, 12, 9759-9768 (2016)
V. Triandafilidi, J Rottler, S.G. Hatzikiriakos, “Molecular Dynamics Simulations of Monodisperse/Bidisperse Polymer Melt Crystallization,” J. Polym. Science, Part B: Polymer Physics, 54, 2318-2326 (2016).
M. Ebrahimi, M. Ansari, and S.G. Hatzikiriakos, “Surface Fractionation Effects on Slip of Polydisperse Polymer Melts,” Physics of Fluids, 28, 093101 (1-11) (2016).
Lev Lewis, M. Derakhshandeh, S.G. Hatzikiriakos, W.Y. Hamad, M.J. MacLachlan,” Hydrothermal Gelation of Aqueous Cellulose Nanocrystal Suspensions,” BioMacromolecules, 27, 2747-2754 (2016).
S. Moradi, N. Hadjesfandiari, S. Toosi, J. Kizhakkedathu, S.G. Hatzikiriakos, “Effect of extreme wettability on platelet adhesion on metallic implants: from superhydrophilicity to superhydrophobicity,” ACS Applied Materials & Interfaces, 8, 17631-17641 (2016).
M.R. Perry, T. Ebrahimi, E. Morgan, P.M. Edwards, S.G. Hatzikiriakos, L.L. Schafer, “Catalytic Synthesis of Secondary Amine Containing Polymers: Variable Hydrogen-Bonding for Tunable Rheological Properties,” Macromolecules, 49, 4423-4430 (2016).
Mirvakili, M.N., H. Van Bui H., J.R. van Ommen, S.G. Hatzikiriakos, P. Englezos, ” Enhanced Barrier Performance of Engineered Paper by Atomic Layer Deposited Al2O3 Thin Films,” ACS Applied Materials & Interfaces, 8, 13590-13600 (2016).
Love-Ese Chile, P. Mehrkhodavandi and S.G. Hatzikiriakos, “A comparison of the rheological and mechanical properties of isotactic, syndiotactic and heterotactic PLA,” Macromolecules, 49, 909-919 (2016).
T. Ebrahimi, S.G. Hatzikiriakos, and P. Mehrkhodavandi, “Synthesis and Rheological Characterization of Star-shaped and Linear Poly(hydroxybutyrate),” Macromolecules, 48, 6672-6681 (2015).
S.G Hatzikiriakos, “Slip Mechanisms in Complex Fluid Flows,” Soft Matter, 11, 7851-7856 (2015).
S. Toosi, S. Moradi, S. Kamal, and S. G. Hatzikiriakos, “Superhydrophobic Laser Ablated PTFE Substrates,” J. Applied Surface Sci., 349, 715-723 (2015).
M. Ebrahimi, M. Ansari and S.G. Hatzikiriakos, “Wall Slip of Polydisperse Linear Polymers using Double Reptation,” J. Rheology, 59, 885-901 (2015).
M. Derakhshandeh, G. Mozaffari, A.K. Doufas and S.G. Hatzikiriakos, “Quiescent Crystallization of Polypropylenes: Experiments and Modelling,” Journal of Polymer Science Part B: Polymer Physics, 52, 1259-1275 (2014).
S. Moradi, P. Englezos and S. G. Hatzikiriakos “Contact Angle Hysteresis in Superhydrophobic Metallic Surfaces”, Langmuir, 30, 3274-3284 (2014).
S. Safiei-Sabet, W. Hamad and S.G. Hatzikiriakos, “The Rheology of Nanocrystalline Cellulose Aqueous Suspensions,” Langmuir, 28, 17124-17133 (2013).
R.L. Webster, N. Noroozi, S.G. Hatzikiriakos, J.A. Thomson, and L.L. Schafer, “Titanium Pyridonates and Amidates: Novel Catalysts for the Synthesis of Random Copolymers,” ChemComm, 49, 57-59 (2013).
My research interest is in the area of organic waste-to-resource recovery and recycling. At present, the research projects may be divided into two major sub-areas: biomass feedstock engineering, and bioconversion processes and systems.
Biomass feedstock engineering
Research activities include the characterization, preprocessing, storage and quality control of biomass as the main components of the supply chain logistics, which bridges the gap between biomass harvesting and bioenergy production in a variety of biorefineries. The biomass feedstock may be in non-densified form such as the high-moisture forest and agricultural residues, or densified form such as wood pellets. The goal is to better manage the biomass and products with potential economic benefits and improve their long-term sustainability. Our research work is in line with the biomass supply and utilization industries’ overall strategy to maintain both the quantity and quality of biomass feedstock during handling, transportation and storage.
Bioconversion processes and systems
Research activities on bioconversion processes and systems are primarily focused on aerobic composting and anaerobic fermentation of non-woody biomass/organic wastes. Odor emission can still be a significant problem in today’s composting practice. The feasibility of using an integrated approach for odor management is being investigated. It involves monitoring of odor emissions and implementing odor control techniques such as biofiltration, which can be applied to other odor-generating industries. Anaerobic digestion of organic wastes for biogas production has environmental benefits in terms of reduced odour and greenhouse gas emissions. By incorporating genome sequencing analysis in our study, we found that diverse microbial communities are taking part in the biohydrogen production process and certain microbes could still be dominant in producing hydrogen without the need to pretreat the seed sludge as most other researchers did. The metabolic pathway for biohydrogen production was affirmed via relationship analysis of the soluble metabolite products. Besides, we have identified the optimal operational conditions that could lead to enhanced biohydrogen productivity. These techniques can be extended to analyze biomethane production.
· He, X., A.K. Lau, S. Sokhansanj, C.J. Lim and X.T. Bi. 2014. Application of a model to simulate the wetting and drying processes of woody biomass in the field. Drying Technology. In press.
· Yazdanpanah, F., S. Sokhansanj, C.J. Lim, A.K. Lau, X.T. Bi, P.Y. Lam and S. Melin. 2014. Effectiveness of purging on preventing gas emission buildup in wood pellet storage. In press.
· Yazdanpanah, F., S. Sokhansanj, C.J. Lim, A.K. Lau, X. Bi and S. Melin. 2014. Stratification of off-gases in stored wood pellets. Special Issue, Biomass and Bioenergy. DOI: 10.1016/j.biombioe.2014.04.019.
· He, X., A.K. Lau, S. Sokhansanj, C.J. Lim, X.T. Bi and S. Melin. 2014. Quantification of gas emissions from stored softwood chips as solid biofuels. International Journal of Environmental Science and Technology. DOI: 10.1007/s13762-014-0541-z.
· He, X., A. K. Lau, S. Sokhansanj, C.J. Lim, X.T. Bi and S. Melin. 2014. Investigating gas emissions and dry matter loss from stored biomass residues. Fuel 134: 159-165.
· Yazdanpanah, F., S. Sokhansanj, C.J. Lim, A.K. Lau, X.T. Bi, P.Y. Lam and S. Melin. 2013. Potential for flammability of gases emitted from stored wood pellets. Canadian Journal of Chemical Engineering 92(4): 603-609.
· He, X., A.K. Lau, S. Sokhansanj, C.J. Lim, X.T. Bi, S. Melin and T. Keddy. 2013. Moisture sorption isotherms and drying characteristics of aspen. Biomass and Bioenergy 57: 161-167.
· Won, S.G., S.B. Baldwin, A.K. Lau and M. Rezadehbashi. 2013. Optimal operational conditions for biohydrogen production from sugar refinery wastewater in an ASBR. International Journal of Hydrogen Energy 38:13895-13906.
· Oveisi, E., A. K. Lau, S. Sokhansanj, C.J. Lim, X. Bi, S. Larsson and S. Melin. 2013. Wood pellet breakage due to free fall. Powder Technology 235: 493-499.
· Naimi, L.J., S. S. Sokhansanj, A.R. Womac, X. Bi, C.J. Lim, A.K. Lau, T. Sowlati and S. Melin. 2013. Development of size reduction equations for calculating energy input for grinding lignocellulosic particles. Applied Engineering in Agriculture 29(1): 93-100.
· Tooyserkani, Z., S. Sokhansanj, X.T. Bi, C.J. Lim, A.K. Lau, J. Saddler, L. Kumar, P.S. Lam, S. Melin. 2013. Steam treatment of softwood particles to produce torrefied material. Applied Energy 103: 514-521.
· Tooyserkani, Z., L. Kumar, S. Sokhansanj, J. Saddler, X.T. Bi, C.J. Lim, A. Lau, S. Melin. 2013. SO2-catalyzed steam pretreatment enhances the strength and stability of softwood pellets. Bioresource Technology130: 59-68.
· Tooyserkani, Z., S. Sokhansanj, X. Bi, C.J. Lim, J. Saddler, A. Lau, S. Melin, P.S. Lam and L. Kumar. 2012. Effect of steam treatment on pellet strength and the energy input in pelleting of softwood particles. Transactions of the American Society of Agricultural and Biological Engineers (ASABE) 55 (6): 2265-2272.
· He, X., A.K. Lau, S. Sokhansanj, C.J. Lim, X.T. Bi and S. Melin. 2012. Dry matter losses in combination with gaseous emissions during the storage of forest residues. Fuel 95: 662-664.
· Yazdanpanah, F., A.K. Lau, S. Sokhansanj, C.J. Lim, X. Bi and S. Melin. 2012. Resistance of wood pellets to low airflow. Canadian Journal of Chemical Engineering 90(6): 1479-1483.
· Zhang, S., X.T. Bi, A.K. Lau and R. Clift. 2012. Life cycle costing of an integrated animal farm-greenhouse eco-industrial system in British Columbia. Proceedings LCA XI Conference, October 4-6, 2011, Chicago, IL.
· Yazdanpanah, F., S. Sokhansanj, A.K. Lau, C.J. Lim, X. Bi and S. Melin. 2011. Airflow versus pressure drop for bulk wood pellets. Biomass & Bioenergy 35(5): 1960-1966.
· Zhang, W. and A.K. Lau. 2011. Effects of bioadditives on the thermal performance, odor emissions and compost quality for poultry manure composting. International Journal of Environmental Engineering 3(1): 1-17.
· Naimi, L.J., S. Sokhansanj, A.R. Womac, X. Bi, C.J. Lim, A.K. Lau, T. Sowlati and S. Melin. 2011. Development of a population balance model to simulate fractionation of ground switchgrass. Transactions of ASABE 54 (1): 219-227.
· Won, S.G. and A.K. Lau. 2011. Effects of key operating parameters on biohydrogen production via fermentation of sucrose-rich wastewater in an anaerobic sequencing batch reactor. Bioresource Technology 102: 6876-6883.
· Yazdanpanah, F., S. Sokhansanj, A.K. Lau, C.J. Lim, X. Bi and S. Melin. 2010. Permeability of wood pellets in the presence of fines. Bioresource Technology 101: 5565–5570.
· Tumuluru, J. S., S. Sokhansanj, C.J. Lim, X.T. Bi, A.K. Lau, S. Melin, T. Sowlati and E. Oveisi. 2010. Quality of wood pellets produced in BC for export. Applied Engineering in Agriculture 26(6): 1013-1020.
· Ra, C.S. and A.K. Lau. 2010. Swine wastewater treatment using submerged biofilm SBR process: Enhancement of performance by internal circulation through sand filter. Journal of Environmental Engineering – ASCE 136(6): 585-590.
· Lau, A.K., S. Baldwin and M. Wang. 2010. Techno-economic assessment of anaerobic digestion systems for agri-food wastes. Paper No. CSBE 10163, XVIIth World Congress of the International Commission of Agricultural and Biosystems Engineering. June 13-17, Quebec City, QC.
· Lau, A.K., W.L. Cheuk and K.V. Lo. 2009. Degradation of greenhouse twines derived from natural fibers and biodegradable polymer during composting. Journal of Environmental Management 90: 668-671.
· Zhang, W., A.K. Lau and Z.P. Wen. 2009. Preventive control of odor emissions through manipulation of operational parameters during the active phase of composting. Journal of Environmental Science & Health Part B – Pesticides, Food Contaminants and Agricultural Wastes. 44(5): 496-505.
· Lau, A.K., S. Bittman and D. Hunt. 2008. Development of ammoniaemission factors for the land application of poultry manure in the Lower Fraser Valley of British Columbia. Canadian Biosystems Engineering 50: 6.47-6.55.
· Zhang, W. and A.K. Lau. 2007. Reducing ammonia emission from poultry manure composting via struvite formation. Journal of Chemical Technology and Biotechnology 82(6): 598-602.
· Lau, A.K. and K. Cheng. 2007. Removal of odor using biofilter from duck confinement buildings. Journal of Environmental Science and Health, Part A – Environmental Science and Engineering A42 (7): 955-960.