No description available.

No description available.

O mexilhão dourado Limnoperna fortunei é uma espécie exótica que tem causado diversos problemas no ambiente aquático em razão da sua habilidade de formar colônias em estruturas. A espécie adere nas superfícies por filamentos proteicos, causando sérios danos ambientais, sociais e econômicos. A investigação de materiais anti-incrustantes parece ser a alternativa ecológica mais adequada para controle desse molusco. Nesse trabalho foram estudadas as propriedades físico-químicas e a preparação de materiais poliméricos para testes de adesão em campo para cotejar a densidade de incrustação do mexilhão. Foram executados testes de caracterização dos materiais com a finalidade de quantificar parâmetros associados a adesão e a aplicabilidade do material em condições submersas. Foram utilizadas cinco diferentes amostras de poliuretano, desenvolvidos pelo Grupo de Química Analítica e Tecnologia de Polímeros /IQSC-USP, e outros três materiais, aço inoxidável, alumínio e PVC, e então determinados os parâmetros de molhabilidade das proteínas adesivas e as propriedades da superfície. A relação entre a molhabilidade da proteína e os parâmetros químicos de superfície (energia livre de superfície, e seus componentes de dispersão e polaridade) foram examinados com base na tensão superficial crítica, no trabalho de adsorção e no trabalho da adesão. Os resultados sugerem que os materiais que possuem baixa energia livre de superfície têm baixa molhabilidade da proteína. Foi verificado uma relação entre o aumento do componente polar dos materiais quando o trabalho de adsorção diminui para as proteínas, o que significa, que a adsorção das moléculas de proteínas em uma superfície não polar é predominante em relação àquela de uma superfície polar, em solução aquosa. A densidade de mexilhões aderidos nas placas testes, em campo, não mostrou associação com os valores medidos da energia livre de superfície e do componente de dispersão. Contudo, foi observado que as resinas de poliuretano com polaridade na faixa de 1,03-1,14 mJm-2 mostraram-se altamente eficientes, incrustação < 0,5%, como revestimento anti-incrustante. / The gold mussel Limnoperna fortunei is an exotic specie that has been causing many problems in aquatic environment due its aggregation on structures of non polar materials. The specie attaches on surfaces by means of protein filaments causing serious social, economic and environmental damages. The investigation of antifouling materials seems to be a good ecological alternative to control this mussel aggregation. This work has studied the preparation and the physical chemical properties of polymeric materials to be employed in field experiment adhesion tests to quantify the mussel fouling density. Studies were performed for materials characterization in order to quantify parameters associated with adhesion and other materials suitabilities in submerged conditions. Five different polyurethane samples, developed by the Group of Analytic Chemistry and Technology of Polymers /IQSC-USP, and three well-known commercial materials, stainless steel, aluminum and PVC, were used. The proteins wettability and surface properties were evaluated for the aforementioned materials. The relationship between the protein wettability and the surface chemical parameters such as surface free energy, dispersion and polar components were examined based on critical surface tension, work of the adsorption and work of the adhesion. The results suggest that materials with low surface free energy have low protein wettability, i.e., the polar component of materials increases when the work of adsorption decreases for both proteins, which means, the adsorption of native and synthetic protein molecules on a non polar surface is predominant compared to a polar surface, in aqueous solution. The mussel\'s density attachment on test coupons, in field experiment, did not show any correlation with surface free energy and dispersion components values. However, it was observed that polyurethane resins with polarity in the range of 1.03-1.14 mJm-2 showed a good performance, attachment < 0.5%, as anti-fouling coating.

Typescript. / Thesis (PhD)--Macquarie University (Division of Environmental & Life Sciences, Dept. of Chemistry & Biomolecular Sciences), 2005. / Includes bibliographical references. / Microelectrode voltammetry -- Experimental -- Microelectrode fabrication -- Characterisation of the carbon film surface: Surface stability - X-ray photoelectron spectroscopy - Raman spectroscopy - Capacitance - Edge plane concentration - Potential window - Surface concentration of alkenes and alkynes - Outer sphere electron transfer using hexaamineruthenium (III) chloride - Reduction of potassium hexacyanoferrate (III) - Anodic oxidation: diol to dione; dopamine and ascorbic acid - Surface oxidation - Ferrocene in a non aqueous solvent -- Selectivity: Formation of carboxylic acid groups on a carbon film surface by ferrous II sulfate complex oxidation - Ethanol modified carbon film surface - Modification of carbon film microelectrode surface using aromatic amines - Modification of carbon film surfaces to form a dual functional ascorbic acid barrier -- In vivo anti fouling properties of surface modified carbon film microelectrodes -- Conclusion. / In this thesis a procedure is presented for the fabrication of a microelectrode to monitor the neurotransmitter dopamine in vivo. The microelectrodes are fabricated by in situ pyrolysis of acetylene under a nitrogen blanket onto a quartz capillary. The carbon film was then anodically oxidised in the presence of 2,4-dinitroaniline. These microelectrodes are stable, provide the physical strength to penetrate brain tissue, have a low capacitance, are resistant to fouling in vivo and selectively suppress the endogenous ascorbic acid which oxidises at the same potential as dopamine. With such properties the carbon film microelectrode appears ideally suited for fast scanning cyclic voltammetric studies of cationic neurotransmitters such as dopamine in vivo. / xxviii, 323 p. ill

abstract: With the application of reverse osmosis (RO) membranes in the wastewater treatment and seawater desalination, the limitation of flux and fouling problems of RO have gained more attention from researchers. Because of the tunable structure and physicochemical properties of nanomaterials, it is a suitable material that can be used to incorporate with RO to change the membrane performances. Silver is biocidal, which has been used in a variety of consumer products. Recent studies showed that fabricating silver nanoparticles (AgNPs) on membrane surfaces can mitigate the biofouling problem on the membrane. Studies have shown that Ag released from the membrane in the form of either Ag ions or AgNP will accelerate the antimicrobial activity of the membrane. However, the silver release from the membrane will lower the silver loading on the membrane, which will eventually shorten the antimicrobial activity lifetime of the membrane. Therefore, the silver leaching amount is a crucial parameter that needs to be determined for every type of Ag composite membrane. This study is attempting to compare four different silver leaching test methods, to study the silver leaching potential of the silver impregnated membranes, conducting the advantages and disadvantages of the leaching methods. An In-situ reduction Ag loaded RO membrane was examined in this study. A custom waterjet test was established to create a high-velocity water flow to test the silver leaching from the nanocomposite membrane in a relative extreme environment. The batch leaching test was examined as the most common leaching test method for the silver composite membrane. The cross-flow filtration and dead-end test were also examined to compare the silver leaching amounts. The silver coated membrane used in this experiment has an initial silver loading of 2.0± 0.51 ug/cm2. The mass balance was conducted for all of the leaching tests. For the batch test, water jet test, and dead-end filtration, the mass balances are all within 100±25%, which is acceptable in this experiment because of the variance of the initial silver loading on the membranes. A bad silver mass balance was observed at cross-flow filtration. Both of AgNP and Ag ions leached in the solution was examined in this experiment. The concentration of total silver leaching into solutions from the four leaching tests are all below the Secondary Drinking Water Standard for silver which is 100 ppb. The cross-flow test is the most aggressive leaching method, which has more than 80% of silver leached from the membrane after 50 hours of the test. The water jet (54 ± 6.9% of silver remaining) can cause higher silver leaching than batch test (85 ± 1.2% of silver remaining) in one-hour, and it can also cause both AgNP and Ag ions leaching from the membrane, which is closer to the leaching condition in the cross-flow test. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2017

O mexilhão dourado Limnoperna fortunei é uma espécie exótica que tem causado diversos problemas no ambiente aquático em razão da sua habilidade de formar colônias em estruturas. A espécie adere nas superfícies por filamentos proteicos, causando sérios danos ambientais, sociais e econômicos. A investigação de materiais anti-incrustantes parece ser a alternativa ecológica mais adequada para controle desse molusco. Nesse trabalho foram estudadas as propriedades físico-químicas e a preparação de materiais poliméricos para testes de adesão em campo para cotejar a densidade de incrustação do mexilhão. Foram executados testes de caracterização dos materiais com a finalidade de quantificar parâmetros associados a adesão e a aplicabilidade do material em condições submersas. Foram utilizadas cinco diferentes amostras de poliuretano, desenvolvidos pelo Grupo de Química Analítica e Tecnologia de Polímeros /IQSC-USP, e outros três materiais, aço inoxidável, alumínio e PVC, e então determinados os parâmetros de molhabilidade das proteínas adesivas e as propriedades da superfície. A relação entre a molhabilidade da proteína e os parâmetros químicos de superfície (energia livre de superfície, e seus componentes de dispersão e polaridade) foram examinados com base na tensão superficial crítica, no trabalho de adsorção e no trabalho da adesão. Os resultados sugerem que os materiais que possuem baixa energia livre de superfície têm baixa molhabilidade da proteína. Foi verificado uma relação entre o aumento do componente polar dos materiais quando o trabalho de adsorção diminui para as proteínas, o que significa, que a adsorção das moléculas de proteínas em uma superfície não polar é predominante em relação àquela de uma superfície polar, em solução aquosa. A densidade de mexilhões aderidos nas placas testes, em campo, não mostrou associação com os valores medidos da energia livre de superfície e do componente de dispersão. Contudo, foi observado que as resinas de poliuretano com polaridade na faixa de 1,03-1,14 mJm-2 mostraram-se altamente eficientes, incrustação < 0,5%, como revestimento anti-incrustante. / The gold mussel Limnoperna fortunei is an exotic specie that has been causing many problems in aquatic environment due its aggregation on structures of non polar materials. The specie attaches on surfaces by means of protein filaments causing serious social, economic and environmental damages. The investigation of antifouling materials seems to be a good ecological alternative to control this mussel aggregation. This work has studied the preparation and the physical chemical properties of polymeric materials to be employed in field experiment adhesion tests to quantify the mussel fouling density. Studies were performed for materials characterization in order to quantify parameters associated with adhesion and other materials suitabilities in submerged conditions. Five different polyurethane samples, developed by the Group of Analytic Chemistry and Technology of Polymers /IQSC-USP, and three well-known commercial materials, stainless steel, aluminum and PVC, were used. The proteins wettability and surface properties were evaluated for the aforementioned materials. The relationship between the protein wettability and the surface chemical parameters such as surface free energy, dispersion and polar components were examined based on critical surface tension, work of the adsorption and work of the adhesion. The results suggest that materials with low surface free energy have low protein wettability, i.e., the polar component of materials increases when the work of adsorption decreases for both proteins, which means, the adsorption of native and synthetic protein molecules on a non polar surface is predominant compared to a polar surface, in aqueous solution. The mussel\'s density attachment on test coupons, in field experiment, did not show any correlation with surface free energy and dispersion components values. However, it was observed that polyurethane resins with polarity in the range of 1.03-1.14 mJm-2 showed a good performance, attachment < 0.5%, as anti-fouling coating.

Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose, has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. In the search for less harsh, greener membrane manufacture, the combination of cellulose and ionic liquid is of high interest. Due to the abundance of OH groups and hydrophilicity, cellulose-based membranes have high permeability and low fouling tendency. Membrane fouling is one of the biggest challenges in membrane industry and technology. Accumulation and deposition of foulants onto the surface reduce membrane efficiency and requires harsh chemical cleaning, therefore increasing the cost of maintenance and replacement. In this work the resistance of cellulose 5 membranes towards model organic foulants such as Suwanee River Humic Acid (SRHA) and crude oil have been investigated. Cellulose membrane was tested in this work for oil-water (o/w) separation and exhibited practically 100 % oil rejection with good flux recovery ratio and membrane resistivity. The influence of anionic, cationic and ionic surfactant as well as pH and crude oil concentration on oil separation was investigated, giving a valuable insight in experimental and operational planning.

Cette thèse porte sur l’élaboration et l’étude des performances de membranes d’ultrafiltration PVDF-TiO2 possédant des propriétés anti-colmatantes et photo-induites. La membrane est obtenue par application de la méthode de séparation de phases induite par un non-solvant sur un collodion de polyfuorure de vinylidène au sein duquel ont été incorporées des nanoparticules de TiO2. Il est montré : i) que la presence des nanoparticules de TiO2 les propriétés membranaires, et notamment le flux de perméat, par rapport à la membrane PVDF ; ii) que l’augmentation de la température de préparation de la membrane permettait de modifier la structure membranaire, en passant d’une morphologie constituée principalement de macrovides (dite en “doigts de gants”) à des températures basses à une morphologie spongieuse, contenant des pores de plus petite taille, à température élevée. Au-delà de la structure membranaire, des propriétés telles que la perméabilité, la porosité, la résistance mécanique, la cristallinité et les propriétés thermiques sont également influences par les changements de température de formation. Lorsque les membranes PVDF-TiO2 sont mises en oeuvre en mode photo-filtration (c.-à-d. filtration avec irradiation ultraviolette (UV) continue sur la membrane), le flux à l’eau pure de la membrane PVDF-TiO2 est encore augmenté, du fait du phénomène d’hydrophilicité photo-induite des nanoparticules de TiO2. Des premières estimations suggèrent que la photo-filtration par les membranes PVDF-TiO2 serait une économiquement rentable, car le gain en termes de filtration et qualité d’eau l’emporterait sur le cout énergétique induit par l’irradiation UV. En outre, l’efficacité de la photo-filtration a été évaluée avec des solutions d’alimentation synthétiques contenant des composés inorganiques et organiques représentatifs des eaux de surface. Il a été montré que si la plupart des ions inorganiques communément rencontrés dans l’eau potable n’ont aucun effet sur l’efficacité de la photo-filtration, la coexistence de Cu2+ et HCO3- dans l’eau d’alimentation entraîne un colmatage inorganique sévère qui inhibe le phénomène hydrophilicité photoinduite. En outre, la membrane PVDF-TiO2 présente également des flux plus élevés et une activité photocatalytique lors de la photo-filtration de solutions contenant des matières colmatantes organiques comme les acides humiques ou l’alginate de sodium. En conclusion, la membrane composite PVDF-TiO2 a démontré des propriétés et des performances significativement améliorées par rapport à la membrane PVDF, a fortioti lorsqu’elle est mise en oeuvre dans un système de photo-filtration sous irradiation UV. Ainsi, ce sont des matériaux prometteurs pour des applications membranaires en traitement de l’eau. / This thesis deals with the elaboration and performance of a specific type of ultrafiltration membrane with anti-fouling and photo-induced properties, the PVDF-TiO2 composite membrane. The membrane was fabricated via the nonsolvent-induced phase separation method by incorporating titanium dioxide (TiO2) nanoparticles into the polyvinylidene fluoride (PVDF) polymer matrix. The TiO2 nanoparticles played a significant role in facilitating the membrane formation process and improving the composite membrane properties compared to the neat PVDF membrane. It was demonstrated that, by changing the membrane preparation temperature, the membrane structure could be affected dramatically, notably the morphological dominance of finger-like macrovoids at lower temperatures and their diminution in both size and number when temperature increased. Other membrane properties also saw systematic transitions with changes in formation temperature, as characterized by permeability, porosity, mechanical strength, crystallinity, and thermal properties. In terms of performance, the PVDF-TiO2 membrane exhibited superior permeate flux compared to the neat PVDF membrane. More importantly, when being operated in photo-filtration mode (i.e. filtration with continuous ultraviolet (UV) irradiation on the membrane), the pure water flux of PVDF-TiO2 membrane could be further increased, thanks to the enhanced hydrophilicity of the membrane, which comes from the photo-induced hydrophilicity phenomenon of TiO2. Preliminary estimations suggest that photo-filtration is a cost-effective method, as the benefit from enhanced water output outweighs the extra energy demand for UV irradiation. Furthermore, the efficiency of photo-filtration was evaluated with synthetic feed solutions containing inorganic and organic contents representative in surface water. It was identified that, while most of the common inorganic ions in drinking water had no effects on photo-filtration efficiency, the coexistence of Cu2+ and HCO3- in the feed led to severe inorganic fouling and inhibited the photo-induced hydrophilicity phenomenon. Besides, the PVDF-TiO2 membrane also showed its stronger flux performance and photocatalytic activity during photo-filtration of solutions containing organic foulants like humic acids or sodium alginate. In conclusion, the PVDF-TiO2 composite membrane exhibited much improved properties and performance compared to the neat PVDF membrane, and even stronger performance when operated in photo-filtration mode. Thus, it is a promising candidate to be used in membrane-based applications for water treatment.

Today the medical field is struggling to decrease bacteria biofilm formation which leads to infection. Also, biomedical devices sterilization has not changed over a long period of time which has resulted in high costs for hospitals healthcare managements. The objective of this project is to investigate electro-dynamic effects by surface energy manipulation as potential methods for preventing bacteria biofilm growing on medical devices. Based on electrokinetic environments two different methods were tested: rejection bacteria dielectrophoretic forces feasibility by numerical simulations; and electrowetting-on -dielectric by the fabrication of golden interdigitated electrodes on silicon glass substrates covered by a Teflon layer. In the first experiment, numerical simulations of gold electrodes in buffer solution and frequencies were carried out to determine the forces required to reject bacteria. In the second experiment, interdigitated gold electrodes coated with a dielectric Teflon layer, were characterized in terms of breakdown voltage, dielectric adhesion and contact angle in terms of applied voltage. Finally the effect of EWOD on bacterial adhesion was tested. The project resulted in promising simulation results for bacteria rejection using dielectrophoresis due to the wide range of frequency that rejects the modelled bacteria. However, practical experiments such as electrowetting-on-dielectric must verify this at incubation times larger than 24 hours in spite of the Teflon non-adhesive properties. / <p>opponent Alex Grossm ann Colin</p> / VRI

No description available.