abstract: Water recovery from impaired sources, such as reclaimed wastewater, brackish groundwater, and ocean water, is imperative as freshwater resources are under great pressure. Complete reuse of urine wastewater is also necessary to sustain life on space exploration missions of greater than one year’s duration. Currently, the Water Recovery System (WRS) used on the National Aeronautics and Space Administration (NASA) shuttles recovers only 70% of generated wastewater.1 Current osmotic processes show high capability to increase water recovery from wastewater. However, commercial reverse osmosis (RO) membranes rapidly degrade when exposed to pretreated urine-containing wastewater. Also, non-ionic small molecules substances (i.e., urea) are very poorly rejected by commercial RO membranes. In this study, an innovative composite membrane that integrates water-selective molecular sieve particles into a liquid-barrier chemically resistant polymer film is synthetized. This plan manipulates distinctive aspects of the two materials used to create the membranes: (1) the innate permeation and selectivity of the molecular sieves, and (2) the decay-resistant, versatile, and mechanical strength of the liquid-barrier polymer support matrix. To synthesize the membrane, Linde Type A (LTA) zeolite particles are anchored to the porous substrate, producing a single layer of zeolite particles capable of transporting water through the membrane. Thereafter, coating the chemically resistant latex polymer filled the space between zeolites. Finally, excess polymer was etched from the surface to expose the zeolites to the feed solution. The completed membranes were tested in reverse osmosis mode with deionized water, sodium chloride, and rhodamine solutions to determine the suitability for water recovery. The main distinguishing characteristics of the new membrane design compared with current composite membrane include: (1) the use of an impermeable polymer broadens the range of chemical resistant polymers that can be used as the polymer matrix; (2) the use of zeolite particles with specific pore size insures the high rejection of the neutral molecules since water is transported through the zeolite rather than the polymer; (3) the use of latex dispersions, environmentally friendly water based-solutions, as the polymer matrix shares the qualities of low volatile organic compound, low cost, and non- toxicity. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2016

The use of carbon fibre-reinforced plastic technology is steadily gaining traction in the modern automotive industry as a lightweight alternative to conventional materials. The versatile chemical resistance of polyamide resins combined with the high strength properties of carbon fibre filler content aims to meet this growing need in the industry. By employing a number of accelerated and amplified ageing techniques, this work hopes to assess the resilience of carbon fibre-reinforced polyamide composites in a variety of foreseeable chemical, temperature, moisture, and stress environments. The resins included in this characterization study include polyamide-6 (PA6) and polyamide-6,6 (PA6/6). The carbon fibre-reinforced composite specimens are subject to long term immersion in commercial automotive fluids at room and elevated temperatures. Results show that the mechanical properties of both polyamide resins are sensitive to windshield washer fluid exposure, regardless of temperature. The significant drop in glass transition temperature and greater elongation at break confirmed a plasticization effect. The Young’s modulus and tensile strength experienced a loss of approximately 40% at saturation. Elevated temperatures resulted in increased fluid sorption rates of antifreeze and E-20 gasoline into the PA6 composite specimens. Likewise, a corresponding drop in PA6 composite mechanical properties was noted for the antifreeze and E-20 gasoline at elevated temperatures. The mechanical properties of the PA6/6 composite were largely retained in all tested automotive fluids, except windshield washer fluid, at elevated temperatures. The effect of absorbed fluid on mechanical properties tended to increase with higher fibre loadings for the PA6/6 composite and lower fibre loadings for the PA6 composite. Finally, a single parameter acoustic emission testing technique was employed to assess internal damage of stressed PA6 composite specimens exposed to different temperature and humidity levels. However, there was no discernible correlation between environmental stress conditions and internal damage for short term exposure times. / Thesis / Master of Applied Science (MASc) / The use of carbon fibre-reinforced plastic technology is steadily gaining traction in the modern automotive industry as a lightweight alternative to conventional materials. The versatile chemical resistance of polyamide resins combined with the high strength properties of carbon fibre filler content aims to meet this growing need in the industry. By employing a number of accelerated and amplified ageing techniques, this work assessed the resilience of carbon fibre-reinforced polyamide composites in a variety of foreseeable chemical, temperature, moisture, and stress environments. The composite only showed significant sensitivity to windshield wiper fluid in the tests.

The aim of this study was to investigate the diffusion of chloride ions into concrete samples that were exposed in scenarios that simulate the splash, tidal, atmospheric, and immersed portions of a marine structure. To study the atmospheric deposition, the project also investigated the relationship between chloride ion deposition on the wet candle and its accumulation into concrete samples. Results from the wet candle experiment indicated that between 2% and 45% of the chlorides deposited per square meter of exposed area could be found within the concrete samples. After 6 months, slag G1a blocks showed the most resistance to chloride penetration in the tidal and splash simulations. After 10 months of exposure, fly ash samples had the slowest rates of diffusion in the tidal simulation while the fly ash + silica fume samples and the slag samples measured similar rates of diffusion within the tidal zone. After 90 days of curing, cylinders composed of 20% fly ash & 8% silica fume measured the highest average resistivity values and were found to be less vulnerable to chloride ion penetration than the 20% fly ash and the 50% slag concrete through rapid migration tests. / by Victor Anthony Echevarria. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

The durability of Reinforced Concrete (RC) structures in the Marine environment is causing serious concern in the structural infrastructure. Reinforced concrete structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that causes degradation is Chloride Diffusion, due to shrinkage, atmospheric corrosion, and tide-induced wet and dry conditions at the air-water interfaces of coastal structures. Therefore, chloride diffusivity, which correlates with the electrical resistivity, has a significant impact on the durability of concrete. Concrete chloride diffusivity has been experimented by multiple agencies and researchers on sound concrete, but there is a considerable need for investigation of the durability of cracked concrete in the marine environment. The two test methods carried out are presented: Standardized American Society for Testing and Materials (ASTM) C1202 for Rapid Chloride Permeability (RCP) and ASTM D257 for Surface Resistivity (SR), and Nordtest (NT) Build 492 for Rapid Chloride Migration (RCM) and Bulk Resistivity (BR) for both sound (uncracked) and cracked (micro and macro) concrete. The limitations of the ASTM method, due to measurements before the steady-state migration is reached, does not account for leakage in cracked concrete, and the heating of the specimen due to higher current that increase the conductivity are indicated. The Rapid Chloride Migration test provides for the non-steady state of diffusion. Again, Bulk Resistivity, in contradistinction to Surface Resistivity is more accurate for cracked concrete. The correlation betweeen RCM-BR are plotted. Chloride Permeability/Migration is an important parameter that governs the Durability of Concrete. The principal contribution is the highlighting of the inadequacy of the current widely used standard ASTM C1202 for diffusivity testing, and the need for revision with further investigation. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Master of Science / Department of Chemical Engineering / Larry E. Erickson / Polycarbonate products have been used extensively world wide for decades because they are lightweight, shatter-resistant and considered to be safe. Polycarbonate is a thermoplastic that is used to make compact discs, phones, lenses, and food contact products such as water bottles, baby bottles and food storage containers. For more than half century, there has been interest in polycarbonate (PC) products and the monomer bisphenol-A (BPA) because BPA can leach from food polycarbonate containers. The environmental fate for both chemicals in air, water and soil is of interest, also. To understand the fate of polycarbonate, its main degradation pathways, main degradation mechanisms and main products are reviewed. These pathways are thermal degradation, photo-degradation and hydrolysis under different conditions. Furthermore, key topics like PC degradation kinetics and PC chemical resistance are part of this comprehensive discussion. The biodegradation of BPA has been thoroughly studied. About twelve lab methods for environmental fate are summarized and reviewed to understand the “big picture” for BPA degradation. This includes screening tests, which assess the ready and inherent degradability, to simulation tests for surface waters, soils and wastewater treatment systems. The testing of all methods is examined under conditions close to the real environment fate. Furthermore, the fate distribution for BPA based on the Equilibrium Criterion Model (EQC) model is reviewed. Extensive research on polycarbonate and BPA has been conducted in the last fifty years. During this time, both chemicals have been studied and tested by industry and government agencies. The pharmacological test results from major studies indicate that consumer exposure to BPA at concentrations normally experienced in daily living does not pose a risk to human health. On the other hand, minor toxicological studies indicate potential risks to human health. Research on health and safety are continuing.

This work describes a comparison of biocompatible membranes to encapsulate gas sensors in the human intestinal tract. The goal is to identify semipermeable materials that allow intestinal gases to pass through the membrane while also separating them from other intestinal contents. Important aspects of this study are the membranes’ chemical resistance to gastric acid and their gas permeability. Chemical resistance was assessed by submerging selected membranes in artificial gastric acid. Surface structure of membrane samples before and after the acid treatment was compared using scanning electron microscopy and signs of degradation were documented. To characterize the membranes in terms of their gas permeability, an experimental setup was developed to measure average airflow through the membranes. A constant pressure of 7 kPa was applied across the membrane and flow rate Q of air was measured over a predefined surface area A. This evaluation marks the first step in the development of an ingestible capsule for in-vivo analysis of intestinal gases.

This paper reports the development of an Alkali Activated Binder (AAB) with an emphasis on the performance and the durability of the AAB-matrix. For the development of the matrix, the reactive components granulated slag and coal fly ash were used, which were alkali activated with a mixture of sodium hydroxide (2 - 10 mol/l) and aqueous sodium silicate solution (SiO2/Na2O molar ratio: 2.1) at ambient temperature. A sodium hydroxide concentration of 5.5 mol/l revealed the best compromise between setting time and mechanical strengths of the AAB. With this sodium hydroxide concentration, the compressive and the 3-point bending tensile strength of the hardened AAB were 53.4 and 5.5 MPa respectively after 14 days. As a result of the investigation of the acid resistance, the AAB-matrix showed a very high acid resistance in comparison to ordinary Portland cement concrete. In addition, the AAB had a high frost resistance, which had been validated by the capillary suction, internal damage and freeze thaw test with a relative dynamic E-Modulus of 93% and a total amount of scaled material of 30 g/m2 after 28 freeze-thaw cycles (exposure class: XF3).

There are applications of refractory concretes for places where these are exposed to corrosive environments. This diploma thesis deals with both description the corrosive effects and methodology of their testing. One of the most important properties of materials, affecting the chemical corrosion resistance, is their density. The practical part of the thesis is focused on testing the refractory concretes which are currently used for applications. The aggregates were tested for the resistance to sulfuric acid.

The aim of this study was to assess the strength, durability properties and corrosion resistance of concrete samples using supplementary cementitious blended materials. In this investigation, three supplementary concrete materials (SCMs) were used together with ordinary Portland Cement (OPC) to form cementitious blends at different proportions. The supplementary materials are silica fume (SF), ground granulated blast furnace slag (GGBS) and fly ash (FA). Sixteen (16) different proportions of the cementitious blends were produced. Tests carried out on concrete samples include slump test, compressive strength, oxygen permeability, sorptivity, porosity, chloride conductivity test, resistance to chloride and sulphate attack. The electrode potentials of tested samples were also observed using electrochemical measurements. Concrete specimens prepared with 10%, 20%, 30%, 40%, up to 60% of blended cements replacement levels were evaluated for their compressive strength at, 7, 14, 28, 90 and 120 days while the specimens were evaluated for durability tests at 28, and 90 days respectively. The results were compared with ordinary Portland cement concrete without blended cement. Voltage, and temperature measurements were also carried out to understand the quality of concrete. The corrosion performance of steel in reinforced concrete was studied and evaluated by electrochemical half-cell potential technique in both sodium chloride, and magnesium sulphate solutions respectively. The reinforced concrete specimens with centrally embedded 12mm steel bar were exposed to chloride and sulphate solutions with the 0.5 M NaCl and MgSO4 concentrations respectively. An impressed voltage technique was carried out to evaluate the corrosion resistance of the combination of quaternary cementitious blended cement, so as to get the combination with optimum performance. Improvement of strength, durability, and corrosion resistance properties of blended concrete samples are observed at different optimum percentages for binary, ternary and quaternary samples. The effect of cementitious blends is recognized in limiting the corrosion potential of the tested SCM concrete samples. Generally, the cementitious blends with limited quantity of SF to 10% have the potential to produce satisfactory concrete. These should however be used for low cost construction, where high quality concrete is not required. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)

Made available in DSpace on 2016-03-15T19:36:56Z (GMT). No. of bitstreams: 1 Thiago Ramos Stellin Malagrino.pdf: 4441654 bytes, checksum: 6ca4cb745da024c77c96b57a51ae6f04 (MD5) Previous issue date: 2016-01-26 / Polycarbonate, an amorphous engineering polymer, has excellent mechanical strength and although it s good chemical resistance, its interaction with some types of alkali and some organic solvents is weak. The main objective of this work was to study the effect of the inclusion of nanometric particle size of natural sodium clay (named Nanolite) and sodium clay treated with quaternary ammonium salt (named Cloisite 15A) in resin processing in order to investigate the variations in chemical properties, transparency and molecular structure. The characterization of nanocomposite was performed using methods of Scanning Electron Microscopy (SEM), Molar Mass Characterization by Mark-Houwink-Sakurada equation, Differential Scanning Calorimetry (DSC), Melt Flow Rate (MFR), Differential Thermal Analysis (DTA), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Chemical Resistance obtained by the contact angle technique / Fowkes method. Optical, thermal, physical and chemical testing indicated that the molecular structure of PC after the inclusion of clays remained unchanged showing no irreversible degradation. The analysis of chemical resistance through the contact angle method showed significant improvement in the surface free energy of the nanocomposites when using the organoclay (Cloisite 15A) and partial improvement when used natural sodium clay (Nanolite). The decrease in surface free energy, indicates a likely improvement in the chemical resistance of the nanocomposites. / O Policarbonato, polímero de engenharia de estrutura amorfa, possui excelente resistência mecânica, e embora possua boa resistência química, deixa a desejar no que se refere ao contato com alguns tipos de álcalis e solventes orgânicos. O objetivo principal deste trabalho foi de estudar comparativamente o efeito da inclusão de partículas nanométricas de argila sódica natural (Nanolite) e argila sódica tratada com sal quaternário de amônio (Cloisite 15A), no processamento da resina a fim de investigar as variações ocorridas nas propriedades químicas e consequentemente, na transparência e estrutura molecular. A caracterização do nanocompósito foi realizada por meio de métodos de Microscopia Eletrônica de Varredura (MEV), massa molar calculada pela equação de Mark-Houwink-Sakurada, Calorimetria Diferencial por Varredura (DSC), Índice de Fluidez (IF), Análise Térmica Diferencial (DTA), Espectroscopia no Infravermelho por Transformada de Fourier (FTIR), Difração de Raios X (DRX) e Resistência Química calculada através da técnica de ângulo de contato / método de Fowkes. Os ensaios óticos, térmicos, físicos e químicos indicaram que a estrutura molecular do PC após a inclusão das argilas permaneceu inalterada, sem degradação irreversível. A análise da resistência química através do método de ângulo de contato apresentou significativa melhora na energia livre superficial dos nanocompósitos quando utilizada a argila organofílica (Cloisite 15A) e, melhora parcial quando utilizada a argila sódica natural (Nanolite). A queda da energia livre superficial, indica que existe uma provável melhora na resistência química dos nanocompósitos.