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Ultrasound can be used to create free radicals by growth and collapse of cavitation bubbles. These free radicals have potential use in various fields. The formation of free radicals can be monitored by decrease in T1 during NMR experiments due to paramagnetic effects. Our goal is to develop a method in which ultrasound is used to enhance NMR. By irradiating the sample during analytical measurements, we can decrease T1 which can be used as a non-toxic contrast agent1 producing hydroxyl radicals from the water in the body, invoke NMR enhancement using dynamic nuclear polarization2, control and understand polymer reactions3,4, and study the formation of radicals in chemical systems with EPR5. The experiments conducted indicated a decrease in T1 when ultrasound was applied. A maximum decrease was observed when 104 W of ultrasound power was applied and with higher concentrations of radical producing species. Through the experiments it was evident that the sample temperature increased during sonication. To counter this, gated sonication was used to minimize temperature increase. During sonication, the sample was vigorously mixed. Experiments where the sample was mixed through alternate means and theoretical simulations indicate that sample mixing gives an apparent decrease in T1. In situ sonication to decrease T1 shows promise. The question remains if the decrease is due to a combination of radical production and mixing or just an artifact of sample mixing. This is a difficult parameter to determine but future experiments will attempt to supply further conclusions. / Master of Science

La spécificité des émulsions de Pickering repose sur la présence de particules stabilisantes, substituant l'utilisation de tensio-actifs. Les particules s'adsorbent de manière irréversible aux interfaces des gouttes d'émulsions, leur conférant une stabilité à long terme.
L'objectif de cette thèse a été de comprendre, développer et optimiser des procédés permettant la fabrication de différents types d'émulsions de Pickering grâce à des nanoparticules de silice. Trois projets ont vu le jour dans ce travail : (i) Tout d'abord une approche théorique concernant l'étude physico-chimique des interfaces d'émulsions de Pickering stabilisées par des nanoparticules de silice individuelles non- agrégées. L'adsorption de ces nanoparticules sous forme de mono- ou multi- couches aux interfaces des gouttes d'émulsion a pu être mise en évidence en fonction du ratio Huile/Silice intégré au milieu. A haut ratio, le diamètre des gouttes d'émulsion dépend des paramètres de formulation. Des monocouches de nanoparticules peuvent s'adsorber aux interfaces avec un taux de couverture maximal de 54% à la surface des gouttes d'huile. Tandis qu'à bas ratio, le diamètre des gouttes dépend du procédé de fabrication de l'émulsion. Des multicouches de nanoparticules s'adsorbent aux interfaces. (ii) La taille des gouttes d'émulsion a ensuite été réduite par divers procédés afin d'obtenir des nanoémulsions de Pickering, également appelées NanoPickering. La première étape consistait à tester la viabilité de telles émulsions en les fabriquant par un procédé fort en énergie, i.e. la sonication. Dans un second temps un procédé faible en énergie a été utilisé : la nanoprécipitation. Il a ainsi été possible d'obtenir des nanoémulsions de Pickering stables sur plus d'un mois. Cependant, la quantité d'huile maximale incorporable au système final reste faible (environ inférieure à 1wt%). (iii) Une nouvelle application a été développée en parallèle permettant de formuler des émulsions foisonnées de Pickering, intégralement stabilisées par des nanoparticules. Il est possible d'obtenir deux types d'émulsions foisonnées de Pickering : les premières ont une très forte teneur en air ; les secondes sont stables en termes de hauteur grâce à un phénomène de gélification qui a lieu après un changement d'état macroscopique.
L'ensemble de ces résultats confirme que les émulsions de Pickering offrent encore à ce jour la possibilité de découvrir de toutes nouvelles applications fabriquées par des procédés innovants. Par exemple, les nanoémulsions sans émulsifiant émulsifiées de manière spontanée, ou encore les émulsions foisonnées intégralement stabilisées sans émulsifiant. De plus, les approches théoriques restent également nombreuses, et les études des phénomènes interfaciaux sont encore des questions scientifiques très actuelles / Pickering emulsions are emulsions stabilized by solid particles in opposition to emulsifiers-stabilized emulsions. The stabilization of Pickering emulsions comes from a strong adsorption of solid particles at the oil-water interface that builds a rigid barrier against coalescence. The aim of this work was to understand, develop and optimize methods for the fabrication of different types of Pickering emulsions stabilized by silica nanoparticles. Three mains axes can be exposed: (i) Firstly, a theoretical approach on the physico-chemical interfacial phenomena of Pickering emulsions stabilized by non-aggregated individual silica nanoparticles. Adsorption as mono- or multi-layers can be reached depending the Oil/Silica ratio. Two behaviors were observed: At high oil/silica mass ratio, the oil/water interface was covered by a monolayer of nonaggregated silica particles. Stable emulsions were stabilized by a monolayer of silica particles at 54% coverage of the oil droplets surface. Oil droplet diameter depends on formulation parameters. Adsorption as multilayers was reached at lower oil/silica mass ratio and oil droplet diameter depends on fabrication process. (ii) Droplets diameters could be reduced thanks to various processes in order to obtain Pickering nanoemulsions, also called NanoPickering. The first step was to test the viability of such emulsions using a high energy process (sonication). Then, a low energy process (nanoprecipitation) was used. Stable Pickering nanoemulsions can be made on more than one month. However, the oil quantity obtained in the final media is low (less than 1wt%). (iii) In parallel, a new application was developed allowing the formulation of Pickering aerated emulsions, totally stabilized by nanoparticles. Two types of Pickering whipped emulsions can be made. One which has high air content or one which has a stable height, thanks to a gelification phenomenon. This occurs after a macroscopic change of state. All of these results confirm that Pickering emulsions offer the opportunity to discover new applications made by innovative processes. For instance, NanoPickering made by spontaneous emulsification, or Pickering whipped emulsion fully stabilized without emulsifiers. Moreover, theoretical approaches and interfacial phenomena studies are still current scientific questions

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Donghai Wang / Scott R. Bean / Sorghum has been considered one of the best species dedicated to biofuel production because of its drought tolerance, low fertilizer or pesticide input, established production systems, and genetic diversity. The mission of this research was to better understand the relationship among "genetic-structure-function-conversion." The main focus of this research was to study the impact of sorghum proteins on ethanol fermentation and to investigate novel methods for evaluation of sorghum fermentation quality. Changes of sorghum protein in digestibility, solubility, and microstructure during mashing were characterized. Sorghum proteins tended to form highly extended, strong web-like microstructures during mashing. The degree of protein cross-linking differed among samples. Formation of web-like microstructures due to cross-linking reduced conversion efficiency. A rapid method for extracting proteins from mashed and nonmashed sorghum meal using sonication (ultrasound) was developed, with which the relationships between the levels of extractable proteins and ethanol fermentation properties were determined. There was a strong relationship between extractable proteins and fermentation parameters. Ethanol yield increased and conversion efficiency improved significantly as the amount of extractable proteins increased. The Rapid-Visco Analyzer (RVA) was used to characterize pasting properties of sorghum grains. Results showed a strong linear relationship between ethanol yield and final viscosity, as well as setback. A modified RVA procedure (10 min) with an application of α-amylase was developed to simulate the liquefaction step in dry-grind ethanol production. There was a remarkable difference in mashing properties among the sorghum samples with the normal dosage of α-amylase. The modified RVA procedure is applicable not only for characterization of mashing properties but also for prediction of tannin content and for optimization of [alpha]-amylase doses for starch liquefaction. A small-scale mashing (SSM) procedure requiring only 300 mg of samples was investigated as a possible method of predicting ethanol yield of sorghum grain. There was a strong linear correlation between completely hydrolyzed starch (CHS) from SSM and ethanol yields from both traditional and simultaneous saccharification and fermentation procedures. CHS was a better indicator for predicting ethanol yield in fermentation than total starch.

A proposta deste trabalho busca avaliar a obtenção da celulose a partir do bagaço de cana-de-açúcar, os meios de obtenção da nanocelulose a partir da celulose por ultrasonicação, bem como a análise das propriedades do nanocompósito EVA/nanocelulose por meio do estudo das propriedades físicas e químicas do nanocompósito e do EVA puro. Inicialmente foi obtida celulose a partir das fibras de bagaço de cana-de-açúcar por meio de métodos químicos de deslignificação e branqueamento. A hidrólise ácida permitiu a obtenção de nanoestruturas de celulose em meio aquoso e o método de sonicação em solução com água/DMF/etanol se mostrou eficiente para melhor controle do tamanho e dispersão das nanoestruturas de celulose. As nanoestruturas de celulose foram caracterizadas por espalhamento dinâmico de luz (DLS), microscopia eletrônica de transmissão (TEM), difração de Raio X (DRX), análise termogravimétrica (TGA) e espectroscopia vibracional de absorção no infravermelho com transformada de Fourier (FTIR). Os resultados mostraram tamanho inferior à 100nm, cristalinidade superior à 70% e decomposição térmica se iniciando por volta de 185°C para as partículas de nanocelulose. Na segunda parte do trabalho foram processados filmes flexíveis de: EVA puro, EVA com 1% de nanocelulose e EVA com 3% de nanocelulose. Os filmes processados foram analisados por calorimetria exploratória diferencial (DSC), análise termogravimétrica, ensaio mecânico de resistência à tração e microscopia eletrônica de varredura (MEV). Os dados de resistência à tração e módulo Young exibiram um aumento dos valores de resistência dos compósitos de EVA/NC em relação ao EVA puro. O compósito EVA/NC não apresentou partículas aglomeradas. A ausência de aglomerados no compósito está relacionada ao reforço mecânico conferido ao material processado. / The aim of this work is to evaluate the production of cellulose from sugarcane bagasse, the means of obtaining nanocellulose from cellulose by ultrasonication, as well as the analysis of the properties of the nanocomposite EVA/nanocellulose by studying the physical properties and chemical properties of nanocomposite and pure EVA. Initially, cellulose was obtained from the sugarcane bagasse fibers by means of chemical delignification and bleaching methods. The acid hydrolysis allowed to obtain cellulose nanoparticles in aqueous medium and the sonication method in water / DMF / ethanol solution proved efficient for better control of the size and dispersion of the cellulose nanoparticles. Cellulose nanoparticles were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and infrared Fourier transform infrared spectroscopy (FTIR) ). The results showed size less than 100nm, crystallinity greater than 70% and thermal decomposition starting at about 185°C for the nanocellulose particles. In the second part of the work, flexible films of: pure EVA, EVA with 1% of nanocellulose and EVA with 3% of nanocellulose were processed. The processed films were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis, mechanical tensile strength test and scanning electron microscopy (SEM). The tensile strength data and Young modulus showed an increase in the EVA/NC composite strength values over pure EVA. The EVA/NC composite showed no agglomerated particles. The absence of agglomerates in the composite is related to the mechanical reinforcement given to the processed material.

Chlorine as a disinfectant reacts with natural organic matter to produce undesired and possibly carcinogenic halogenated disinfection by-products (DBPs), which are regulated by the U.S. Environmental Protection Agency under the Disinfectant/Disinfection By-products Rule (DBPR). In order to comply with the increasingly stringent regulations, alternative disinfectants such as ozone, UV irradiation, and chloramines have been investigated. Unfortunately, these alternatives have their own limitations and disadvantages as well. Sonication is another alternative that has not yet received adequate research. The hydroxyl radicals, tensile stresses, and fluid shear generated during sonication may inactivate microorganisms. The goals of this research were to evaluate the effectiveness of sonication alone and combined sonication and chlorination for inactivation of E. coli. Four stages of disinfection experiments were conducted: chlorine alone, sonication alone, combined sonication and chlorination, and heating alone. Experiments were conducted in laboratory prepared phosphate buffered saline. The variables tested included the chlorine dose, chlorine contact time, sonication time, sonication system (probe or bath), sonication power-to-volume ratio, and sonication frequency. E. coli was enumerated by use of pour plates and/or membrane filtration before and after disinfection. Substantial temperature and turbidity increases were recorded after sonication, especially at 900 W/L. After 10 minutes of sonication at 900 W/L, the temperature and turbidity of the experimental solution rose up to 77oC and 23 NTU, respectively. At both 180 W/L and 900 W/L, sonication alone demonstrated little inactivation (less than 1 log10) of E. coli for temperatures below 60oC and greater than 7 log10 inactivation at temperatures over 60oC. The results from heating only experiments confirmed that temperature was responsible for the inactivation rather than other ultrasonic wave effects Sequential application of sonication and chlorination was ineffective at inactivating E. coli. Chlorination alone achieved higher levels of E. coli inactivation than the combination of both disinfectants. When sonication and chlorination were applied simultaneously, the inactivation was greater than the additive effect of two disinfectants, indicating that there were synergistic effects between sonication and chlorination. For example, at 900 W/L, chlorination alone at 0.6 mg/L for 2 minutes provided 1.2 log10 inactivation and sonication for 2 minutes alone provided less than 1 log10 inactivation of E. coli. When the two disinfectants were applied simultaneously, 4.5 log10 was achieved. Sonication may have weakened the cell membranes, causing them to be more susceptible to chlorine disinfection.

In this study, the effects of neutral particles addition on the breakage of wastewater flocs toimprove the efficiency of sonication pretreatment for UV disinfection process have been studied.Kaolin particles as a potentially useful material that is neutral, natural and cheap were added towastewater samples prior to sonication. Results obtained in this study indicated that hard andsmall kaolin particles do not have any significant effect on the particle breakage efficiency byultrasound. The addition of kaolin particles did not significantly increase the cavitation activity(as characterized by potassium iodide actinometry) either. These findings contradict earlierreports that neutral particles can act as nucleation sites and hence enhance cavitation intensity. Inthis work, sonication of wastewater samples for 60s in the absence of kaolin particles resulted inan approximately one log decrease in the number of surviving bacteria colonies at the tailinglevel and 1.4 log units increase at the initial slope of coliform removal in UV dose responsecurve, however addition of kaolin particles prior sonication did not significantly affect the UVdose response curve .The results presented in this study should be treated as preliminary andfurther detailed investigations are needed to better evaluate this issue.

D. Tech. Chemical Engineering / Concerns for the limitations of conventional technology for acid mine water treatment and the potential use of waste water have led to increased interest in membrane technologies. Studying the physical properties of nanofiltration membranes is a very important development in nanofiltration separation process. For optimum separation performance, the nanofiltration membranes have to possess certain physical properties, given the appropriate interactions with solutes in the process stream. This study investigated the performance evaluation of Nano-Pro-3012 and NF90 membranes in the treatment of synthetic wastewater effluents and acid mine water and the influence of membrane characteristics on retention in nanofiltration. The research was aimed to evaluate the performance of a new acid stable nanofiltration material (Nano-Pro-3012) produced by Bio Pure Technology for the removal of heavy metals from shaft 8 at Rand Uranium wastewater treatment plant and compare with a commercially available nanofiltration membrane.

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The enzyme, &amp / #946 / -galactosidase (E.C.3.2.1.23) has been used for dairy industry for removing lactose from milk and milk by-products. In this study, three strains namely L. plantarum NCIMB 1193, L. plantarum DSM 20246 and L. plantarum E081 were used for &amp / #946 / -galactosidase release by sonication method. The peak of the total enzyme activity was found to be corresponding to late logarithmic or early stationary phase of all strains. As a disruption method sonication was used for the release of &amp / #946 / -galactosidase. Meanwhile, the sonication time was optimized for each strain. The peak of the enzyme activity was observed between 210 seconds and 270 seconds of sonication period. It was also found that sonication did not decrease the viability of L.plantarum NCIMB 1193 significantly. Liquid nitrogen cell disruption method was also used to compare the results with those obtained by sonication method. For characterization &amp / #946 / -galactosidase, cell-free crude extract of sonicated cell culture of L.plantanrum NCIMB 1193 was used. Optimum pH found as 7.2, and optimum temperature range was found between between 350 C to 400 C. Km and Vmax values were found as 3.47 mM and 1.721 (&amp / #956 / mol / min per mg protein) respectively from Lineweaver-Burk plot. Km and Vmax values were found as 4.064 mM and 1.863 (&amp / #956 / mol / min per mg cell-free crude extract) respectively from Eadie-Hofstee plot. The number of ligand binding sites (napp) on a molecule of &amp / #946 / -galactosidase was found as 1.03 which indicates that the number of ligand binding sites on the enzyme is one.