Polymer electrolyte membrane fuel cells (PEFCs) have long been thought of as a promising clean alternative energy electrochemical device. They are lightweight, highly efficient, modular and scalable devices. A fuel such as H2 or methanol that can be readily produced from a variety of sources can be utilized in PEFCs to generate electricity with low or no emissions. Despite these advantages, fuel cell technologies have failed to reach mass commercialization mainly due to short operational lifetimes and the high cost of materials. In particular, the polymer membrane and the catalyst layer have been problematic in reducing the material cost. Currently, platinum is the dominant material used to catalyze fuel cell reactions. However platinum is very expensive and scarce. In order to pursue the mass commercialization of fuel cells, two methods have been proposed: 1) increasing the utilization of platinum to lower the loading required, and 2) replacing platinum completely with a non-precious material. The latter has been suggested to be the long term solution due to the increasing cost of platinum. This thesis explores the elimination of platinum through the use of nanostructured non-precious metal catalysts for polymer electrolyte fuel cells. Several catalysts have been synthesized without the use of platinum that are active for the oxygen reduction reaction (ORR) which occurs at the cathode. Three different synthetic techniques were utilized using different nitrogen precursors. Aside from the different nitrogen precursors, each set of experiments utilize a different approach to optimize the oxygen reduction performance. Different characterization techniques are used to learn more about the ORR on non-precious metal fuel cells. The first experiment utilizes ethylenediamine, a well-known nitrogen precursor for non-precious metal fuel cell catalysts. Ethylenediamine is deposited onto two different porous carbon black substrates to determine the effectiveness of different porosities in creating active sites for the ORR. Of the two carbon black species, Ketjenblack EC-600JD and Ketjenblack ED-300J, the former was found to be more porous and effective. This result was mainly attributed to the increased surface area of the carbon black which allowed for better dispersion and a greater active site density. In this experiment, the coating of ethylenediamine on carbon black was also refluxed for 3 hours prior to the pyrolysis. It was found that refluxed catalyst samples showed much improved performance than catalyst samples without this procedural modification. The next experiment utilized cyanamide as a nitrogen precursor. Cyanamide was chosen due to its ability to form larger amounts of pyridinic nitrogen on the surface of the catalyst after a high temperature pyrolysis stage. The catalysts were heat-treated at 1000oC and the performance was measured. NH3 was introduced during the pyrolysis, which could remove the excess coating from the carbon surface, and increase the surface area of the catalyst by unblocking the carbon pores. A third modification to the procedure was carried out, where the heat-treated sample was ball-milled, re-coated, and heat-treated again in ammonia conditions to increase the nitrogen functionalities and increase the active site density. The performance was slightly increased from the original heat-treated sample. However due to the decreased surface area, the limiting current density also decreased. It was believed that ball-milling the sample crushed the pores within the catalyst sample, thereby lowering the active surface area and thus the current density. Therefore, the last sample was prepared similarly to the procedure for the third sample, but without ball-milling. This sample had restored surface area and improved ORR performance over all the synthesized catalyst samples – these experiments allowed for important realizations regarding the nature of the Fe-cyanamide-KJ600 catalysts and allowed for a drastic improvement in onset and half-wave potentials from the first catalyst. The final experiment discussed in this thesis describes the work done with 1,2,4,5-tetracyanobenzene and tetracyanoethylene as phthalcyanine precursors for non-precious metal catalysts (NPMCs). Iron(II) acetate was mixed with these phthalocyanine precursors to form polymer sheets of iron phthalocyanine or its monomeric units. By the creation of these polymer sheets of iron phthalocyanine, it allowed for a uniform distribution of iron centres on the surface of the carbon after a heat-treatment step. This allowed for high active site density through the design of these sheet polymers and prevented agglomeration or blockage of active sites which is thought to be a common problem in the synthesis of many NPMCs. Both tetracyanobenzene and tetracyanoethylene as precursors were tested. The tetracyanobenzene catalyst was heat-treated at different temperature ranging from 700-1100oC and characterized through electrochemical tests for the ORR. As an overall conclusion to this work, several catalyst samples were made and different approaches were successfully employed to improve the ORR performance. Of the synthesis treatments utilized to improve performance, each specific catalyst had different parameters to tweak in order to improve ORR performance. With X-ray photoelectron spectroscopy (XPS) analysis, conclusions were also specific to the catalysts structure and synthesis procedure, however quaternary and pyrrolic nitrogen groups seemed to play an influential role to the ORR final performance. Although relative amount of pyridinic nitrogen was not seen to increase with increasing catalyst performance during the studies; it may still play an essential role in the reduction of oxygen on the catalyst surface. The author of this work has not ruled out that possibility. Several recommendations for future work were suggested to broaden the knowledge and understanding of nanostructure non-precious metal catalysts to design a high performing, durable, and low-cost alternative to platinum based catalysts.

Recent estimates of global maternal mortality indicate that for the first time since the Safe Motherhood Initiative of 1987, deaths due to pregnancy-related causes are on the decline. Defined as the death of a woman while pregnant or within 42 days of termination of pregnancy, maternal mortality is one of the strongest health statistics showing the disparity between poor and rich countries. Although a global decline is documented, challenges to reducing maternal mortality, and meeting Millennium Development Goals (MDGs) for maternal health remain, particularly in many Sub-Saharan African and Southeast Asian countries. This study presents an assessment of Cambodia’s progress towards reaching the Millennium Development Goal of reducing maternal deaths by ¾ by 2015. The report examines issues related to the improvement of maternal health, outlining the magnitude, determinants, and prevention methods of maternal mortality globally and in Cambodia. Cambodia’s health policies and contextual factors impacting the maternal mortality ratio such as dramatic increases of skilled health personnel for delivery, delivery in health facility, and use of antenatal care are identified as key contributors to MMR reduction. Continued progress in reducing maternal mortality in Cambodia requires improvements to midwifery skill, competencies around normal and emergency birthing care, and salaries of midwives as well as an incentive for new graduates to work in the public sector. An increase in the cooperation between government health centers and hospitals are crucial to ensure obstetric referrals, supervision of health center staff, and an improvement in maternal death data collection. Finally a national priority to increase the use of family planning and safe abortion will significantly contribute to the continued reduction of MMR.

Drag reduction is a well-observed phenomenon, it was first observed by the British chemist Toms in 1946, yet its mechanism is still unknown to this day. Polymer Drag reduction has found application in reducing pumping costs for oil pipelines (its use in the Trans Alaska Pipeline has resulted in an increase from 1.44 million bbl./day to 2.1356 million bbl./day), increasing the flow rate in firefighting equipment , and in supporting irrigation and drainage systems. Surfactant drag reducers are used industrially in district heating and cooling systems. Though the fields of Surfactant Drag Reduction and Polymer Drag Reduction are each independently well-developed the effect of their interaction on drag reduction is a less explored phenomenon. Through a well chosen pairing of surfactant and polymer, drag reduction can be maximized while minimizing surfactant and polymer concentrations cutting down on cost and environmental impact. The focus of this work was to determine if there was any positive interaction between the polymers Polyethylene Oxide (PEO) and Anionic PolyAcrylAmide (PAM) and the surfactant Amphosol CG (Cocamidopropyl Betaine) as well as any interaction between the polymers themselves. Both polymers are popular drag reducers while Amphosol is a practically nontoxic (LD50=5g/kg) zwitterionic surfactant and is readily biodegradable. In order to determine if any interaction was present and at what concentration was this most notable 4 techniques were used: Surface tension, Conductivity, Relative Viscosity and Shear Viscosity measurement. From this analysis the polymer Saturation point (PSP), Critical aggregation concentration (CAC) and Critical micelle concentration (CMC) were found as well as the concentrations that optimized the viscosity for the pilot plant runs. The bench scale results were used to pick the optimum concentrations for the polymer surfactant solutions. Pressure readings and flowrate measurements were used to plot the Fanning Friction Factor against the Generalized Reynolds Number for the surfactant polymer mixtures and compared to their pure polymer and surfactant counterparts. The Blasius line was found to hold for water measurements taken and is the base to determine percentage drag reduction. The effect of the presence of amphosol on degradation and overall drag reduction were noted. Other factors considered were pipe diameter and the effect of ionic impurities in the solvent.

Nickeliferous laterite ores are currently processed using complex energy intensive flowsheets. Limited mineral upgrading can be achieved by low-cost mineral processing as the nickel is not found as a separable mineral phase but finely disseminated throughout the host goethite mineral. Whole ore extraction processes are required which result in intrinsically higher capital and operating costs. Market pressure has provided incentives to develop alternative upgrading techniques that can produce a nickel concentrate and reduce the material input to downstream processing facilities. Thermal upgrading through a selective reduction mechanism to produce a ferronickel concentrate has been studied extensively and has shown promising potential. In this research, a two stage selective reduction of nickeliferous laterite ore was investigated at 600oC and 1000 – 1100oC with varying coal and sulphur additions. Experiments showed that the limonite ore could be selectively reduced using a coal additive to a ferronickel and wustite phase. A combination of XRD and bromine/methanol diagnostic leach tests confirmed the presence of metallic nickel and iron in the calcine. Higher degrees of metallization corresponded with higher sulphur additions and growth zone temperatures. Sulphur was added to improve particle growth through the establishment of a Fe-O-S liquid phase, which was found to improve Ni recovery from 13.8% to 75.8% over the range of 0 – 4 wt% S. Ferronickel particles ranging in size from 20 – 60 microns were shown to be present but highly dispersed throughout the upgraded ore. Particle growth improved with higher growth zone temperatures and longer retention times. Magnetic separation of the calcine showed maximum upgrading of grades to 3 – 4 wt% nickel with recoveries ranging from 83.7 – 93.2%. Partial oxidation of wustite particles to magnetite caused the particles to be magnetic and resulted in recovery of unwanted iron oxides. The presence of iron oxide fines was believed to allow for rapid oxidation of wustite phase and also produce slimes that hindered physical separation of the upgraded ore. / Thesis (Master, Mining Engineering) -- Queen's University, 2013-12-29 22:34:20.417

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