Lipid membranes are semipermeable, allowing for water transport across the membrane but rejecting polar solutes and large molecules. Differences in solute concentrations across a lipid membrane lead to differences in the osmotic pressure Δπ causing water to flow towards regions of higher osmotic pressure (higher solute concentration) at speeds of v=-LpΔπ , where Lp is the hydraulic conductivity of the membrane. When a lipid vesicle is placed in a concentration gradient, it is predicted to move to regions of lower concentration due to osmotic flows across the membrane. John Anderson labeled this motion "osmophoresis'' and proposed a theory that predicts the vesicle velocity as U = -½𝛼LpRTG, where 𝛼 is the vesicle radius, RT is the thermal energy, and G=∇C is the imposed concentration gradient. The first experimental demonstration of osmophoresis reported a 1 μm/s migration velocity of DMPC vesicles in a 10 mM/mm sucrose gradient created between two dialysis tubes. However, Anderson's theory predicts that osmophoretic velocity should be four order of magnitude smaller than the observed velocity. A central goal of this Dissertation is to resolve this discrepancy either by validating Anderson's theory or by identifying relevant physics it may lack. Our central conclusion is that Anderson's theory is likely correct and experimental reports of faster osmophoresis can be attributed to convective flows---particularly, density driven flows caused by the solute gradients. To quantify osmophoresis, we need a steady concentration gradient and micron sized lipid vesicles which are predicted to move faster than smaller vesicles and can be observed by optical microscopy. In Chapter 1, I review methods for generating concentration gradients, including glass chambers for chemotaxis assays and microfluidic devices for sustained operation. In Chapter 2, I review the methods used in this Dissertation for producing giant lipid vesicles, which include film rehydration and emulsion templating techinques. Chapter 3 describes a quantitative investigation of the convective flows induced by solute gradients within microfluidic gradient generators. Solute gradients drive fluid motions due to combinations of gravitational body forces and diffusioosmotic surface forces. I quantify and model how these flows depend on solute type, concentration gradient, device height, and solution viscosity. I describe how undesired convective flows can be mitigated by adding thickening agents to increase the solution viscosity or by density matching between high and low concentration solutions. Chapter 4 describes experiments to measure the osmophoresis of lipid vesicles in osmotic gradients while controlling for convective flows. I use density matched sugar solutions to create 315 mM/mm gradients within a commercial gradient generator (Dunn chamber) while limiting convective flows to less than 20 nm/s. I quantify the motions of lipid vesicles and tracer particles by optical microscopy and observe that both move in a common direction at speeds of 0-10 nm/s. According to Anderson's theory, the expected osmophoretic velocity of lipid vesicles in the solute gradient we applied is 4 nm/s assuming a membrane permeability is 100 μm/s. By contrast, the previously reported motion of DMPC vesicles at speeds of 1 um/s in a 10 mM/mm gradient could not be reproduced and was likely caused by inadequate control over gradient-induced convective flows. One strategy to enhance vesicle motion in osmotic gradients is to increase the membrane permeability---for example, by addition of water channel proteins like aquaporins. The pursuit of giant vesicles with high permeability creates a challenge for measuring the membrane permeability owing to rapid vesicle swelling/shrinking in response to osmotic shocks. Chapter 5, I demonstrate how to use photo-initiated polymerization to create a light-induced osmotic shock to vesicles. Vesicle swelling rate in response to this osmotic shock can infer the membrane permeability when the reaction is fast enough. Chapter 6, I conclude how to set up a steady solute gradient with minimal convective flows to study the slow osmophoresis and highlight some specific future directions for osmophoresis, such as enhancing osmophoretic motion by increasing membrane permeability and designing a cell sorting microfluidic device to isolate living cells based on their size and permeability.

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Detta arbete utreder möjligheten att säkra vattentillgången i Mönsterås kommun med hjälp av en avsaltningsanläggning för bräckvatten från östersjön. Det är högst troligt ett sådant vattenverk skulle kunna uppföras i kommunen och dessutom ge ett vatten med lägre halter av oönskade ämnen än vatten renat med konventionella metoder från yt- och grundvatten till en marginellt högre kostnad.I arbetet redovisas kortfattat principen för avsaltning med RO (Reverse osmosis). Uppbyggnaden av två vattenverk som använder den tekniken och likt Mönsterås ligger i Kalmarsund beskrivs. Med information från sjökort och kartor har troliga råvattentillgångar i kommunen identifierats och utifrån dessa grundar sig förslagen för placering.Med hjälp från ett flertal kontakter i branschen har en enklare projektering gjorts för ett vattenverk med kapacitet på 3000 kubikmeter dricksvatten per dygn.I resultatet redovisas några förslag på placering av ett vattenverk. / This work investigates the possibility of securing the water supply in Mönsterås municipality with the help of a desalination plant for brackish water from the Baltic Sea. It is highly likely that such a waterworks could be built in the municipality and also provide water with lower levels of unwanted substances than water purified by conventional methods from surface and groundwater at a marginally higher cost.In the work, the principle of desalination with RO (Reverse osmosis) is briefly presented. The construction of two waterworks that use this technology and, like Mönsterås, is located in Kalmarsund is described. With information from nautical charts and maps, probable raw water resources in the municipality have been identified and based on these, the proposals for placement are based.With the help of several contacts in the industry, a simpler design has been made for a water treatment plant with a capacity of 3000 cubic meters of drinking water per day.The result presents some suggestions for placement of a desalination plant.

Co-precipitation and absorption methods were investigated for removal of boron from produced water, which is groundwater brought to the surface during oil and natural gas extraction. Boron can be toxic to many crops and often needs to be controlled to low levels in irrigation water. The present research focused on synthetic reverse osmosis (RO) concentrate modeled on concentrate expected from a future treatment facility at the Arroyo Grande Oil Field on the central coast of California. The produced water at this site is brackish with a boron concentration of 8 mg/L and an expected temperature of 80°C. The future overall produced water treatment process will include lime softening, micro-filtration, cooling, ion exchange, and finally RO. Projected boron concentrations in the RO concentrate are 20 to 25 mg/L. Concentrate temperature will be near ambient. This RO concentrate will be injected back into the formation. To prevent an accumulation of boron in the formation, it is desired to reduce boron concentrations in this concentrate and partition the boron into a solid sludge that could be transported out of the area. The primary method explored for boron removal during this study was adsorption and co-precipitation by magnesium chloride. Some magnesium oxide tests were also conducted. Jar testing was used to determine the degree of boron removal as a function of initial concentration, pH, temperature, and reaction time. Synthetic RO concentrate was used to control background water quality factors that could potentially influence boron removal. The standard synthetic RO concentrate contained 8 g NaCl/L, 150 mg Si/L and 30 mg B/L. After synthetic RO concentrate was prepared, amendments (e.g. sulfate, sodium chloride) were added and the pH adjusted to the desired value. Each solution was then carried through a mixing and settling protocol (5 min at 200 RPM, 10 min at 20 RPM, followed by 30 min settling and filtration). Boron concentrations from the jar tests were determined using the Carmine colorimetric method. Boron removal with magnesium chloride was greatest at a pH of 11.0. At this pH 87% of boron was removed using 5.0 g/L MgCl2◦6H2O at 20°C. Mixing time did not greatly affect boron removal for mixing periods of 5 to 1321 minutes. This result indicates equilibrium was achieved during the 45-min experimental protocol. Maximum boron removal was observed in the temperature range of 29°C to 41°C. At 68°C boron removal decreased five-fold compared to the reduction observed at 29°C to 41°C. For treatment of the cool concentrate, this relatively low optimal temperature range gives magnesium chloride an advantage over magnesium oxide, which is effective only at high temperatures. Neither sodium chloride nor sodium sulfate affected boron removal by magnesium chloride for the chloride and sulfate concentrations expected in the produced water at this site. In contrast, silica did inhibit boron removal, with removal decreasing from 30% to 5% when silica concentration was increased from 0 to 100 mmols/L. This result was unexpected because other researchers have reported silica is necessary for effective removal of boron by magnesium chloride. To investigate the reasons for the differing boron removal results for magnesium chloride and magnesium oxide, solids produced by the two reagents were compared using X-ray diffraction spectroscopy (XRD). Solids from magnesium chloride contained 30% amorphous material versus 10% for magnesium oxide. The crystalline components from the magnesium oxide treatment were for the most part magnesium oxide, whereas magnesium chloride crystalline solids were a combination of brucite (Mg(OH)2) and magnesium chloride hydroxide. The greater boron adsorption observed with magnesium chloride could thus either be attributed to the greater surface area of the amorphous precipitate and/or the higher boron affinity of brucite and magnesium chloride hydroxide. Adsorption isotherms were plotted for boron removal by magnesium compounds formed during precipitation. Boron adsorption followed a linear isotherm (r2= 0.92) for boron concentrations up to 37.8 mg B/L. While the data also fit Langmuir and Freundlich models the data fell in the linear range of those models. The linearity of the adsorption curves indicates that adsorption sites for boron were not saturated at these concentrations. The linearity means that higher boron concentrations in the RO concentrate will lead to greater mass removal, up to concentrations of at least 37.8 mg/L boron. Using magnesium chloride, boron removal by co-precipitation was more effective than by adsorption to pre-formed precipitate. Removal approximately doubled for a given dose of magnesium chloride. The effectiveness of co-precipitation presumably occurs due to entrapment of boron as the precipitate forms. This study has shown the potential of magnesium chloride as an agent for boron removal by determining those conditions most effective for boron co-precipitation and adsorption. Magnesium chloride has been shown to be more effective than magnesium oxide. Magnesium chloride also out-performed treatment with slaked quicklime, which was tested previously by others. Two important limitations of boron removal with magnesium chloride are the high chemical requirements (5 g/L MgCl2) and sludge production (1 g/g MgCl2 used). These are greatly mitigated by treatment of RO concentrate rather than the full produced water flow. In addition, reagent use and sludge production might be decreased by recycling sludge from the up-front lime softening process. Compared to magnesium oxide, magnesium chloride removes greater quantities of boron per mole of magnesium added (20 mg B/g MgCl2). The magnesium chloride isotherm demonstrated that treatment of RO concentrate required less reagent and produced less sludge per mass of boron removed than treatment of the more dilute feed water.

Water desalination has the potential to alleviate a significant part of the world’s thirst, with a majority of desalinated water capacity coming from seawater reverse osmosis (SWRO). However, SWRO membrane systems suffer from the loss of performance due to biofouling leading to economic costs. There is no control or preventive strategy for SWRO biofouling and current industry practices recommend chemical treatments to restore membrane performance. Chemical cleaning results in high economic costs due to chemical acquisition, storage, transportation, long plant downtimes and ultimately shorter membrane lifetime and early replacement; in addition to the environmental impact associated with disposing of chemicals. Therefore, there is a need for novel effective green cleaning strategies for SWRO to meet the increasing demand for desalinated water while taking care of the environment. Micronanobubbles (MNBs) consist of small gas cavities formed in aqueous solutions. This study evaluates the efficiency of both air-filled micronanobubbles (AMNBs) and CO2 nucleated MNBs as: i) curative cleaning-in-place (CIP) treatments and ii) preventive daily treatments for biofouling over long-term studies. Experiments were performed using the membrane fouling simulator (MFS) under conditions that are representative of SWRO membrane systems. Pressure drop was implemented as the main biofilm growth monitoring parameter as used by standard industry practices. Curative studies showed that both MNBs CIP treatments had high cleaning efficiencies of 49-56% pressure drop recovery. MNBs pressure drop recovery values were close to the conventional chemical cleaning (NaOH/HCl) at 51% and were significantly higher than the hydraulic flush (HF) physical cleaning control at 24%. The pressure drop recovery results were supported by the optical coherence tomography (OCT) images before and after CIP and biomass autopsy results. Similarly, preventive MNBs daily treatments showed a significant delay in the system’s performance decline. This delay was 5.1 days for the CO2 MNBs experiments, 4 days for the AMNBs, and only 0.6 days for the hydraulic flushing treatments compared to the control. Compared to the control the duration of the operation was doubled in time before the cleaning criteria was met. OCT images confirmed biofilm growth delay with lower biomass occurrence.

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High performance engineering materials, poly(arylene ether)s, having very good mechanical properties, excellent oxidative and hydrolytic stability are promising candidates for alternative materials used in the field of Proton Exchange Membrane Fuel Cells (PEMFCs) and Reverse Osmosis (RO) applications. In particular, wholly aromatic sulfonated poly(arylene ether sulfone)s are of considerable interest in the field of PEMFCs and RO, due to their affordability, high Tg, and the ease of sulfonation. Proton exchange membrane fuels cells (PEMFCs) are one of the primary alternate source of energy. A Proton exchange membrane (PEM) is one of the key component in a PEMFC and it needs to have good proton conductivity under partially humidified conditions. One of the strategies to increase proton conductivity under partially RH conditions is to synthesize hydrophobic-hydrophilic multiblock copolymers with high Ion exchange capacity (IEC) values to ensure sufficient ion channel size. In this thesis two multiblock systems were synthesized incorporating trisulfonated hydrophilic oligomers and were characterized in the first two chapters of the thesis. The first multiblock system incorporated a non-fluorinated biphenol-based hydrophobic block. The second study was focused on synthesizing a fluorinated benzonitrile-based hydrophobic block. A fluorinated monomer was incorporated with the aim to improve phase separation which might lead to increased performance under partially humidified conditions. The third study featured synthesis and characterization of a novel hydroquinone-based random copolymer system precursor, which after post-sulfonation, shall form mono-sulfonated polysulfone materials with potential applications in reverse osmosis. The ratio of the amount of hydroquinone incorporated in the copolymer were varied during the synthesis of the precursor to facilitate control over the post-sulfonation process. The simple and low cost process of post-sulfonating the random copolymer enables the precursor to be a promising material to be used in the reverse osmosis application. / Master of Science

Los procesos de membrana han alcanzado una amplia aceptación dentro de diversos campos. Sin embargo, la producción de membranas europea no está en relación con el volumen de su utilización, por lo que interesa desarrollarla. La investigación y desarrollo en la producción de membranas busca obtener membranas con características de separación y resistencia eficaces y cada vez más adaptadas a procesos específicos. La presente tesis entra dentro de esta línea afrontando: 1. La determinación de las variables influyentes en la preparación mediante el método de inversión de fase por inmersión - precipitación de membranas compuestas de Acetato de Celulosa sobre soporte no-tejido dentro de los rangos de ósmosis inversa y nanofiltración. 2. El establecimiento de las bases para la fabricación en máquina de membranas compuestas mediante la comparación de los resultados experimentales del método manual de fabricación con los obtenidos en un prototipo de máquina de fabricación industrial de membranas planas existente en el Departamento de Ingeniería Química y Nuclear de la Universidad Politécnica de Valencia. Los resultados obtenidos permitieron evaluar los efectos de la variación de las condiciones de fabricación sobre el comportamiento y características de la membrana fabricada. No obstante, el método manual presentó elevada dispersión y baja reproducibilidad, si bien, los resultados que se obtienen se pueden considerar orientativos para la fabricación en máquina, si se tiene en cuenta la salvedad de que un soporte de membrana adecuado en el método manual podría no serlo para la fabricación en máquina. / Gozálvez Zafrilla, JM. (1998). Fabricación de membranas de acetato de celulosa aptas para osmosis inversa y nanofiltración mediante el método de inversión de fase [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/4281