Forward osmosis (FO) is one of the emerging membrane technologies in a field of water treatment. The potential advantages of a FO process are lower energy consumption, and higher fouling reversibility compared to other membrane-based desalting technologies, e.g., reverse osmosis and nanofiltration, due to low working pressure. Despite high fouling reversibility, membrane fouling can be still a major obstacle in the FO process. Thus, the employment of spacers can help in enhancing water flux and minimizing membrane fouling. However, the current design of spacers has a potential problem related to spacer fouling, thereby deteriorating the FO process. Therefore, the spacers were examined with the different designs (i.e., hole-type and twisted spacers) fabricated via a 3D-printer for the treatment of shale gas produced water (SGPW). To evaluate the performance of the spacers, either synthetic SGPW or Milli-Q water as feed solution (FS) and different concentration of sodium chloride as a draw solution (DS) were employed. Water flux, reverse solute flux (RSF) and reverse solute flux selectivity (RSFS) were firstly measured with increasing DS concentration with Milli-Q water as FS and a 1-hole spacer exhibited the highest water flux. When increasing FS concentration to 0.3 M NaCl, hole-type spacers exhibited higher water flux than twisted spacers. Therefore, 0-hole and hole-type spacers were selected for SGPW treatment. During SGPW treatment, severe flux decline was observed with all experiments due to the formation of BaSO4 scaling. Flux decline of 1- hole spacers was slightly severer than 0-hole. This might be because scales were broken by high shear force and more covered the membrane surface as shown in SEM images. However, interestingly, hole-type spacers showed no change of pressure drop during SGPW treatment while the pressure drop of the 0-hole spacer increased. Holes of spacers can prevent the accumulation of foulants on the spacer surface, thereby resulting in no change of pressure drop. Physical cleaning with no spacer and the 0-hole spacer showed less than 95% cleaning efficiency while hole-type spacers could enhance the cleaning efficiency and achieve 100%. This might be because the micro-jet induced by holes of the spacer can more readily destroy and remove foulants on the surface.

Sulfonated poly(arylene ether sulfone)s are a class of engineering thermoplastics well-known for their mechanical properties and chemical/oxidative stability. The research in this dissertation focuses on modifying the structure of sulfonated poly(arylene ether sulfone)s to improve membrane performance. Blends of a 20% disulfonated poly(arylene ether sulfone) (BPS20) with poly(ethylene glycol) (PEG) were investigated with the objective of promoting water flux across a reverse osmosis membrane. It was considered desirable to investigate poly(arylene ether sulfone)s with a hydroquinone unit that could be controllably post-sulfonated without degradation, providing a polymer with controlled sulfonation through controlling hydroquinone content. It also avoided the disadvantages noted previously in polymers with post-sulfonated biphenol units. Initial experiments focused on determining sulfonation conditions to confirm quantitative sulfonation of the hydroquinone without side reactions or degradation. A polymer with 29 mole % hydroquinone-containing units was used to study the rate of sulfonation. Successful post-sulfonation was confirmed and reaction conditions were applied to a series of polymers with varying hydroquinone comonomer contents. These polymers were sulfonated, characterized and evaluated for transport properties. Of interest was the high sodium rejection in the presence of calcium, which in the directly copolymerized disulfonated materials is compromised. The post-sulfonated poly(arylene ether sulfone)s showed no compromise in sodium rejection in a mixed-feed of sodium chloride and calcium chloride. In the membrane electrolysis of water, Nafion's high permeability to hydrogen, particularly above about 80 C, results in back-diffusion of hydrogen across the membrane. This reduces efficiency, product purity, and long-term electrode stability. Hydrophilic-hydrophobic multiblock copolymers based on disulfonated and non-sulfonated poly(arylene ether sulfone) oligomers feature a lower gas permeability. Various multiblock compositions and casting conditions were investigated and transport properties were characterized. A multiblock poly(arylene ether sulfone) showed a significant improvement in performance over Nafion at 95°C. Multiblock hydrophilic-hydrophobic poly(arylene ether sulfone)s have been extensively investigated as alternatives for proton exchange membrane fuel cells. One concern with these materials is the complicated multi-step synthesis and processing of oligomers, followed by coupling to produce a multiblock copolymer. An streamlined synthetic process was successful for synthesizing membranes with comparable morphologies and performance to a multiblock synthesized via the traditional method. / Ph. D.

Clean water is critical to the safety, security and survivability of humankind. Nearly 41% of the Earth's population lives in water-stressed areas, and water scarcity will be exacerbated by an increasing population. Over 96% of the total water is saline and only 0.8% is accessible fresh water. Thus, saltwater desalination has emerged as the key to tackle the problem of water scarcity. Our current work deals with the membrane process of reverse osmosis. Sulfonated polysulfones are a potential alternative to state-of-the-art thin film polyamides. Synthesized by step growth polymerization, polysulfone membranes have smooth surfaces and they are more chemically resistant relative to polyamides. Previously studied sulfonated polysulfone membranes were synthesized by direct copolymerization of pre-disulfonated comonomer and the sulfonate ions were placed on adjacent rings of bisphenol moiety. This study focuses on placing the sulfonate ions differently along the polysulfone backbone on isolated rings of hydroquinone moiety, and on adjacent rings of biphenol moiety- and its effect on the transport and hydrated mechanical properties of the membranes. Selective post sulfonation of poly(arylene ether sulfone) in mild conditions was also found to be an effective way to strategically place the sulfonate ions along the backbone of the polymer chain without the need to synthesize a new monomer. Hydroquinone based, amine terminated oligomers were synthesized with block molecular weights of 5000 and 10,000 g/mol. They were post-sulfonated and crosslinked at their termini with epoxy reagents. Such crosslinked and linear membranes had sulfonate ions on isolated rings of hydroquinone moiety. Synthesis and kinetics of controlled post-sulfonation of poly(arylene ether sulfones) that contained biphenol units were also reported. The sulfonation reaction proceeded only on the biphenol rings. The linear membranes had sulfonate ions on adjacent rings of biphenol moieties. The tensile measurements were performed on the membranes under fully hydrated conditions. All membranes remained glassy at values of water uptake. It was found that elastic moduli and yield strengths in the hydroquinone- based linear and crosslinked membranes increased with decrease in water uptakes in the membranes. The effect of plasticization of water superseded the effect of block length and degree of sulfonation in the membranes. The highest elastic modulus of 1420 MPa at lowest water uptake of 18% was observed in cross linked membrane with 50% repeat units being sulfonated (50% repeat units contain hydroquinone)and target molecular weight of 5000 g/mol. However, the hydroquinone membranes broke at low strains of < 20%. The hydrated mechanical properties could be improved by replacing the hydroquinone with biphenol moieties. The biphenol based post-sulfonated membrane showed high elastic modulus that was comparable to the hydroquinone-based counterparts at similar values of water uptake. The biphenol based membrane broke at higher strains of >80%. The post-sulfonated membranes- hydroquinone-based linear and crosslinked membranes and biphenol-based linear membranes had better transport properties than the previously studied sulfonated polysulfones that were synthesized by disulfonated comonomers.The post sulfonated hydroquinone-based membranes did not show a compromise in the rejection of monovalent ions in the presence of divalent ions in mixed feed water. The superior properties of the post-sulfonated membranes can potentially be attributed to the kinked backbone that potentially increased the free volume in the membranes and the sulfonate ions were spaced apart to potentially reduce their chelation with calcium (divalent) ions in mixed feed water. Interestingly, the biphenol based post-sulfonated membranes also did not have any compromise in the rejection of monovalent ions in the presence of divalent ions. This was potentially because the sulfonate ions were spaced far apart on the non-planar biphenol rings. / PHD / According to the World Economic Forum, the water crisis has remained one of the top five global risks that has had a huge impact on the society. The world population has tripled in the twentieth century. Close to 2 billion people live in water scarce regions, 1.2 billion people lack access to safe drinking water, 2.6 billion have little or no access to sanitation and countless die due to diseases transmitted through unsafe water. Industrialization and climate change have worsened the water crisis. Furthermore, in today’s economies food, energy and water are inherently linked. Thus, a water crisis can have a cascading effect on availability of food and energy. To obtain an adequate and sustainable supply of water, it is important to improve already existing methods and develop new and inexpensive technologies for water purification. According to the U.S. geological survey over 96% of the earth’s water is saline. Thus, salt water desalination has emerged as the key to tackle the problem of scarcity of potable water. Reverse osmosis is a membrane-based process for water desalination wherein the membrane allows water to pass through while rejecting salts. The membranes are composed of long chain molecules called polymers. The current state of the art polymeric membrane made of polyamides show high rejection of salts with fast permeation of water. However, these membranes can be degraded by the chlorinated disinfectants added to the feed water. An alternative polymeric material, sulfonated polysulfone, can potentially be applied for reverse osmosis as these polymers are resistant to the chlorinated species. These membranes are composed of a polysulfone with sulfonate ions present randomly on the chain. This study investigates the effect of the position of the ions on the polymer chain. It is found that the membranes ability to reject salt from water can be improved by strategically placing the charged species on the polymer chain.

Brackish waters are now considered valuable alternative water resources. Reverse osmosis (RO) membranes are the most promising candidate for drinking water production through desalination. Low recovery (the fraction of influent water that becomes product water) prevents widespread application of RO inland because of the high cost of waste disposal. The recovery of a brackish RO system is limited by sparingly soluble salts that become supersaturated and precipitate on the membrane surface. Precipitation is controlled through pH adjustment and antiscalant addition; however, at high salt supersaturation, antiscalant control is overcome and precipitation occurs. To further increase RO recovery and avoid precipitation, a three-stage process treated the waste stream (concentrate) of a brackish water RO system through antiscalant degradation, salt precipitation, and solid/liquid separation. Ozone (O3) and hydrogen peroxide (H2O2) were used to degrade antiscalants, pH elevation and base (NaOH/NaHCO3) addition were used to precipitate sparingly soluble salts, and microfiltration (0.1 μm) was used to separate precipitated solids from the water. Optimal parameters (pH, ozone dose, H2O2/O3 ratio, antiscalant type and concentration, water composition) for antiscalant oxidation were determined. The influence of antiscalant type and concentration and pH was investigated for the precipitation and filtration stages. Results were obtained for particle size distribution, extent of precipitation, particle morphology, and particle composition. The effect of ozonation on precipitation and filtration was evaluated, with a comparison to two-stage treatment consisting of precipitation and filtration. Antiscalant oxidation is controlled by bivalent cation coordination, while pH and ozone dose significantly affect the extent of oxidation. The addition of antiscalant prior to precipitation caused changes to particle size and morphology, and results varied with water composition and antiscalant type and concentration. Ozonation, even for small times such as one minute, prior to precipitation and filtration increased calcium precipitation and decomposed the antiscalant enough to remove the effect of the antiscalant on particle characteristics. During ozonation, antiscalants were not completely oxidized, but the partial oxidation products did not seem to affect precipitation. Ozonation also reduced the fouling of microfiltration membranes used for solid/liquid separation. Results indicated concentrate treatment can significantly increase the overall recovery of an RO system. / text

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CIVINS / Systems on modern naval vessels are becoming exclusively dependent on electrical power. One example of this is the replacement of distilling and evaporator plants with reverse osmosis units. As the system is in continuous operation, it is critical to have remote real-time monitoring and diagnostic capabilities. The pressure to reduce shipboard manning only adds to the difficulties associated with monitoring such systems. One diagnostic platform that is particularly well suited for use in such an environment is the non-intrusive load monitor (NILM). The primary benefit of the NILM is that it can assess the operational status of multiple electrical loads from a single set of measurements collected at a central point in a ship's power-distribution network. This reduction in sensor count makes the NILM a low cost and highly reliable system. System modeling, laboratory experiments, and field studies have all shown that the NILM can effectively detect and diagnose several critical faults in shipboard fluid systems. For instance, data collected from the reverse osmosis units for two U.S. Coast Guard Medium Endurance Cutters indicate that the NILM can detect micron filter clogging, membrane failures, and several motor-related problems. Field-tested diagnostic indicators have been developed using a combination of physical modeling and laboratory experiments. / CIVINS

Memoria de Título para optar al título profesional de Ingeniero Agrónomo / En los últimos años se ha evidenciado un progresivo aumento del grado alcohólico de los vinos a nivel nacional e internacional, debido principalmente al cambio climático que ha favorecido la maduración de la uva más temprana, Además, por las últimas tendencias de elaboración de vinos con más estructura que ha generado que se retrase la fecha de cosecha, para conseguir una maduración fenólica más completa. Éste aumento generalizado de alcohol en los vinos ha generado inconvenientes para los consumidores que cada día se ha preocupado más por su salud y/o por moda busca preferentemente vinos con menores niveles de alcohol. Además, influyen imperativos legales relacionadas con las limitaciones de ingestas de alcohol.

Reverse Osmosis membranes have been successfully proven to remove almost 99% of chemicals dissolved in seawater. However, removal of certain trace elements, such as boron is challenging and relatively low for seawater reverse osmosis desalination plants compared to thermal desalination plants. Boron is naturally occurring and is present in seawater at an average concentration of 4.5-5 mg/L. While boron is a vital element, its toxicity has been proven on crops, animals and possibly humans. Additionally, boron should be removed to comply with the current guideline value of 0.5 mg/L, for drinking water, issued by the World Health Organization (WHO), which is barely attained by a single-pass process seawater reverse osmosis plant. Currently, multipass reverse osmosis membrane operations with pH modifications are the only valid method for boron removal. However, this is not economically efficient as it requires higher energy and chemicals consumptions. The objective of this study was to investigate boron removal by commercial TFC RO membranes in addition to custom-made KAUST-synthesized TFC membrane. Five membrane samples were examined: Toray, Sepro, Koch, and KAUST in-house synthesized membrane. Three different feed pH conditions were used: pH6, pH8, and pH10. Filtration experiments were conducted in two parts. In experiment 1, all five membranes were examined for boron rejection in a dead-end permeation system, whereas in experiment 2 the two membranes with the highest boron rejection from experiment 1 were tested in a cross-flow system. Permeate and feed samples were taken continuously and analyzed for boron concentration, rejection calculation. Membrane surfaces were characterized according to hydrophilicity, roughness and surface charge. The results showed for all the tested membranes that boron rejection increased as the feed pH increased. KAUST, defect-free TFC, showed the highest performance for boron rejection for all pH conditions, although, it shows the roughest surface. Toray membranes 80LB and 80B exhibited the second highest boron rejection and had the most negatively charged membrane surfaces. It was observed in this study that the rejection of boron by a membrane is due to size exclusion and charge repulsion mechanisms. It was concluded that, the KAUST, defect free TFC has the potential to be applicable for boron rejection in industrial application as it has better boron rejection than commercially available RO membranes.

Thesis (Ph.D.(Chemistry))--University of Pretoria, 1992. / Includes abstract in English and Afrikaans. Includes bibliographical references.

Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2010. / Committee Chair: Ellery Ingall; Committee Member: Irina Sokolik; Committee Member: Josef Dufek. Part of the SMARTech Electronic Thesis and Dissertation Collection.