http://hdl.handle.net/1974/769 2013-06-18T07:30:34Z 2013-06-18T07:30:34Z Donaldson, Jason http://hdl.handle.net/1974/8048 2013-05-30T05:02:48Z 2013-05-29T04:00:00Z

Title: The Synthesis of Cellulose Graft Copolymers Using Cu(0)-Mediated Polymerization Authors: Donaldson, Jason Abstract: Cellulose is the most abundant renewable polymer on the planet and there is great interest in expanding its use beyond its traditional applications. However, its hydrophilicity and insolubility in most common solvent systems are obstacles to its widespread use in advanced materials. One way to counteract this is to attach hydrophobic polymer chains to cellulose: this allows the properties of the copolymer to be tailored by the molecular weight, density, and physical properties of the grafts. Two methods were used here to synthesize the graft copolymers: a ‘grafting-from’ approach, where synthetic chains were grown outward from bromoester moieties on cellulose (Cell-BiB) via Cu(0)-mediated polymerization; and a ‘grafting-to’ approach, where fully formed synthetic chains with terminal sulfide functionality were added to cellulose acetate with methacrylate functionality (CA-MAA) via thiol-ene Michael addition. The Cell-BiB was synthesized in the ionic liquid 1-butyl-3-methylimidazolium chloride and had a degree of substitution of 1.13. Polymerization from Cell-BiB proceeded at similar but slightly slower rate than an analogous non-polymeric initiator (EBiB). The average graft density of poly(methyl acrylate) chains was 0.71 chains/ring, with a maximum of 1.0 obtained. The graft density when grafting poly(methyl methacrylate) was only 0.15, and this appeared to be due to the slow initiation of BiB groups. Using EBiB to model the reaction and improve the design should allow this to be overcome. Chain extension experiments demonstrated the living behaviour of the polymer. The CA-MAA was synthesized by esterification with methacrylic acid. Reactions of CA-MAA with thiophenol and dodecanethiol resulted in quantitative addition of the thiol to the alkene. The grafts were synthesized by Cu(0)-mediated polymerization from a bifunctional initiator containing a disulfide bond, followed by reduction to sulfides. The synthetic polymers were successfully grafted to CA-MAA but the grafting yield was limited by the low sulfide functionality. Better retention of sulfide functionality is necessary for more efficient grafting. Description: Thesis (Master, Chemical Engineering) -- Queen's University, 2013-05-27 16:21:03.874

2013-05-29T04:00:00Z Poleo , Eduardo E. http://hdl.handle.net/1974/8018 2013-05-02T20:34:58Z 2013-05-02T04:00:00Z

Title: SIMULTANEOUS DEGRADATION OF TOXIC AND VOLATILE SUBSTRATES BY TWO PHASE PARTITIONING BIOREACTOR SYSTEMS: PERFORMANCE CHARACTERIZATION AND RATIONAL POLYMER SELECTION Authors: Poleo , Eduardo E. Abstract: The degradation of toxic and volatile contaminants in aqueous streams is considered a challenge using conventional bioremediation strategies. At moderate concentrations, toxic contaminants induce microbial inhibition, which results in an overall decrease of reaction rates. On the other hand, volatile compounds are often stripped out of solution into the atmosphere during aeration in conventional wastewater treatments, and are not treated. The addition of a second non-aqueous phase with affinities for the contaminants can reduce aqueous concentrations to sub-inhibitory levels and also decrease contaminant volatilization, while still allowing controlled release of contaminants back to the microbial population; such systems have been denoted as Two Phase Partitioning Bioreactor (TPPB). The current work examined and compared the performance of solid-liquid TPPB to a liquid-liquid TPPB and a single phase system. The systems were compared in the simultaneous degradation of phenol and butyl acetate, two substrates known for their relatively high levels of toxicity and volatility, respectively. The solid-liquid TPPB, using 2 polymers selected heuristically, showed an improvement of 40 and 54 % in phenol degradation rates compared to the single phase and the liquid-liquid systems. Additionally, the solid-liquid system presented a 55 and 11 % enhancement in the amount of butyl acetate degraded. At higher initial substrate concentration the solid-liquid TPPB showed an improvement in the phenol degradation rate and the amount of butyl acetate degraded of 44 and 94 % respectively, compared to the single phase system. In order to rationalize polymer screening for solid-liquid TPPBs, selection criteria based on first principles were developed, and were based on consideration of polymer accessibility and polymer-solute thermodynamic affinity. Polymer accessibility was evaluated by considering glass transition temperature (Tg) and degree of crystallinity, while polymer-solute thermodynamic affinity was assessed using three different methods, Hildebrand solubility parameters, Hansen iii Solubility Parameters (HSP) and activity coefficients at infinite dilution. It was found that the HSP method gave the best trends and its predictions had better agreement with the experimental results. Consequent biodegradation experiments with a single, rationally selected polymer, and a mixture of waste polymers, demonstrated the superior performance of rational selected polymers. Description: Thesis (Master, Chemical Engineering) -- Queen's University, 2013-05-02 16:24:39.655

2013-05-02T04:00:00Z PARMAR, RAJESH http://hdl.handle.net/1974/7917 2013-04-24T22:15:29Z 2013-04-24T04:00:00Z

Title: A COMBINED GAS-PHASE AND SURFACE REACTION MECHANISTIC MODEL OF DIESEL SURROGATE REFORMING FOR SOFC APPLICATION Authors: PARMAR, RAJESH Abstract: This study presents a detailed gas-phase and surface kinetic model for n-tetradecane autothermal reforming to deconvolute the complex reaction network that provides the mechanistic understanding of reforming chemistry in a packed-bed reactor. A thermodynamic analysis study for diesel reforming was performed to map the carbon formation boundary for various reforming processes. Through a Langmuir-Hinshelwood-Hougen-Watson (LHHW) type of kinetic model, which was derived using a simple mechanistic study, the need for a detailed kinetic study including both gas-phase reactions and surface reactions was identified. Pt-CGO (Pt on Gd doped CeO2) and Rh-pyrochlore catalysts were synthesized and characterized. In an accelerated test for reforming of commercial-diesel, Rh-pyrochlore catalyst showed stable performance for 24 hrs, whereas Pt-CGO catalyst deteriorated in 4 hrs. Minimum structural change in Rh-pyrochlore catalyst compared to Pt-CGO catalyst was observed using redox experiments. An experimental kinetic study with an inert silica bed provided clear evidence that the gas-phase reactions are important to the kinetics of hydrocarbon reforming. “Reaction Mechanism Generator” (RMG) software was employed to generate a detailed gas-phase kinetic model containing nine thousand three hundred and forty-seven elementary reactions and four hundred and fifty-nine species. The model was validated against n-tetradecane ignition delay data, and inert bed autothermal reforming data. The RMG model was also extended to capture the high pressure and low temperature pyrolysis chemistry to predict pyrolysis experimental data. The reactor simulation using the RMG model identified the detailed chemistry of the reactions in the pre-catalytic zone. Gas-phase oxidation/pyrolysis converts the heavier hydrocarbons and oxygen in the pre-catalytic zone to lower molecular weight products prior to reaching the catalyst surface. The steam reforming reactions that are dominant on the surface of the catalyst primarily involve lower molecular weight oxidation/pyrolysis products. A multi-component micro-kinetic model containing two hundred and seventy surface reactions and fifty-two adspecies was developed using a semi-empirical Unity Bond Index-Quadratic Exponential Potential (UBI-QEP) method. Transition State Theory estimates were used for elementary reactions up to C3 species, and simple fragmentation reactions were assumed for higher hydrocarbon species. Model simulations indicated on the catalyst surface that hydrogen is initially produced by the water-gas-shift reaction and subsequently by steam reforming reactions. A major reaction path for ethylene formation from 1,3 butadiene in the post-catalytic zone of the reactor was also identified. Description: Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2013-04-24 13:23:31.163

2013-04-24T04:00:00Z Gerson, Jonas Elliott http://hdl.handle.net/1974/7840 2013-03-04T21:15:53Z 2013-03-04T05:00:00Z

Title: Electrically Actuated Micropost Arrays for Droplet Manipulation Authors: Gerson, Jonas Elliott Abstract: Precise manipulation of heterogeneous droplets on an open droplet microfluidic platform could have numerous practical advantages in a broad range of applications, from proton exchange membrane (PEM) fuel cells and microreactors, to medical diagnostic platforms capable of assaying complex biological analytes. Toward the aim of developing electrically controllable micropost arrays for use in open droplet manipulation, custom-designed titanium dioxide (TiO2)- loaded poly(dimethylsiloxane) (PDMS) micropost arrays were developed in this work and indirectly mechanically actuated by applying an electric field. Initial experiments explored the bulk properties of TiO2-loaded PDMS films, with scanning electron microscopy (SEM) confirming a uniform TiO2 particle distribution in the PDMS, and tensile testing of bulk films showing an inverse relationship between TiO2 % (w/w) and Young’s Modulus with the Young’s Moduli quantified as 4.22 ± 0.51 MPa for unloaded PDMS, 2.27 ± 0.18 MPa for 10 % (w/w) TiO2, and 1.39 ± 0.20 MPa for 20 % (w/w) TiO2. Following bulk material evaluation, soft lithography methods were developed to fabricate TiO2- loaded PDMS micropost arrays. Mathematical predictions were applied to design microposts of varying shape, length, and gap spacing to yield super-hydrophobic surfaces actuatable by an electric field. Visual inspection and optical microscopy of the resulting arrays confirmed a non- collapsed micropost geometry. Overall, round microposts that were 100, 200, and 300 μm in length, 15 μm in diameter, and spaced 50 μm apart were produced largely free of defects, and used in contact angle measurements and micropost deflection experiments. Droplet contact angles measured on the arrays remained above 120° indicating the arrays successfully provided super- hydrophobic surfaces. Individual microposts deflected most notably above an electric field strength of 520 kV/m (12.5 kV nominal voltage). The ability to mechanically deflect customized microposts using an electric field demonstrated by this work is promising for translating this technology to precise droplet manipulation applications. Indirect actuation of droplets could enable the manipulation of liquids with varying electrical properties, which is a limitation of current micropumping technologies. Once optimized, electrically actuated micropost arrays could significantly contribute to the micro- handling of heterogeneous, highly ionic, and/or deionized fluids. Description: Thesis (Master, Chemical Engineering) -- Queen's University, 2013-03-03 17:25:49.785

2013-03-04T05:00:00Z