Barnacles are dominant hard–fouling organisms in marine waters. They attach to substrates by secreting a complex proteinaceous adhesive. Understanding the chemical composition of this multi–protein underwater adhesive and how it is affected by environmental variables, such as oceanic temperatures, is critical for developing nontoxic solutions to control biofouling. Previous experiments in our lab revealed an inverse relationship between critical removal stress (CRS) and temperatures at which barnacles were reared. Further investigations showed that this correlation is not attributed to differences in physical properties such as barnacle size or short–term changes in the viscosity of adhesive. Therefore, the observed effects may be influenced by a physiological response to temperature during initial growth and development. We hypothesized that rearing temperature affects the expression of proteins found in the adhesive matrix. To elucidate the underlying mechanisms responsible for the temperature effect, we analyzed uncured barnacle adhesive using two-dimensional gel electrophoresis (2DGE) and matrix-assisted laser desorption/ionization-tandem time-of-flight (MALDI-TOF/TOF) mass spectrometry (MS). In our analysis, we 1) detected differences in protein expression at two experimental temperatures (15°C and 25°C) and 2) identified several proteins that may serve functional roles in the process of adhesion. Our data are also consistent with a model that the curing process of barnacle adhesive may be analogous to the process of wound healing in animals.

Increasing water reuse opportunities for communities has become increasingly important as access to clean water is becoming more scarce. Reverse Osmosis (RO) is an advanced treatment technology used in water recycling wastewater for potable reuse applications. RO is a promising technology; however, the membranes have limitations including their high energy demand and their susceptibility to membrane fouling. The main objective of this study was to develop a reproducible method for the fabrication of RO membranes with enhanced flux and reduced susceptibility to fouling. Literature contains numerous publications on fabrication of thin film composite (TFC) RO membranes with high performance. However, the reports lacked all the details needed to fabricate a TFC RO membrane, making it difficult to replicate those published fabrication protocols. Based on the efforts of this study, the membrane fabrication procedures utilized did not yield the same quality and performance as reported in these articles. In this study, five TFC RO control membranes were replicated and compared. The membranes produced an average water flux of 21.9 ± 3.6 L/m2h (LMH) and an average salt rejection of 97.6% ± 2.0%. Based on these results, it was concluded that a reproducible fabrication technique was developed for fabricating consistent and reliable TFC RO membranes. Furthermore, this study investigated the role of fouling on TFC RO membrane performance. Enhancing membrane resistance to fouling helps maintain membrane selectivity, lifespan, and permeability. There has been an increasing interest in the modification of the RO membranes for enhanced hydrophilicity, which leads to improvements in fouling resistance. In this study, a positive and high charge density polymer, polyethylenimine (PEI), was introduced into the membrane matrix in varying layers of the membrane structure. PEI-1 was fabricated in-situ by grafting the PEI onto the polysulfone (PSf) support, while PEI-2 was fabricated via grafting of the PEI onto the membrane PA surface. The resulting membranes were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), and Goniometry. PEI-2 produced a more hydrophilic membrane when compared to PEI-1, however, PEI-1 performed better in terms of flux and selectivity. Multiple model foulants were used for investigating the modified membrane fouling performance. These model foulants were tested at varying concentrations, pH values, and with and without the presence of Ca2+ ions. The model foulants used were bovine serum albumin (BSA), sodium alginate, and humic acid. None of the model foulants resulted in a decrease in performance for the membrane over the duration of the tests (up to 13 hours). Future research is needed to develop a robust protocol for testing the fouling of the produced RO membranes within a reasonable timeframe.

The primary goal of this research was to improve understanding of the fouling of low pressure hollow fiber membranes used in drinking water treatment. The major difference of this study compared to other reported studies was the use of a hollow fiber membrane module at operating conditions mimicking those of full-scale practice. Two poly(vinylidene-fluoroethylene) based hollow fiber membranes (A and B) were tested. Different types of fouling indices (total, hydraulic irreversible, chemical irreversible) developed based on a resistance in series model were used to assess membrane performance. Data from bench-scale and full-scale plants were compared to validate the use of fouling indices. The impact of dissolved organic nitrogen (DON) on membrane fouling was demonstrated with model waters containing humic substances and several model organic nitrogen compounds. Three different natural water sources normalized to the same organic content were tested. Fouling indices determined from the resistance in series model approach were more applicable for natural waters than for model waters. Fouling was proportional to throughput for both raw and pretreated water and at different flux rates. Pretreatment (coagulation) reduced hydraulic irreversible fouling. Most fouling was reversed by hydraulic and chemical cleaning. Specific flux and fouling indices of the bench-scale system were higher than those of the full-scale system but the fouling index ratios were comparable suggesting a similar fouling nature. A minimum of a few days of testing is recommended for longer-term membrane performance assessment. The impact of high DON concentration on membrane fouling was insignificant. Membrane fouling was dependant on foulant properties other than, or in addition to, molecular size and the DON/DOC ratio. With three different natural water sources normalized to a similar organic content, membrane fouling was specific to membrane type and water source. High initial total and hydraulic irreversible fouling rates did not lead to high chemical irreversible fouling rates. It is not possible to generalize the impact of different water sources on membrane fouling. Membrane surface anlyses showed that hydraulically irreversible organic foulants were detected as mostly hydrocarbons/polysaccharides, humic substances and peptide/protein. Humic substances and peptide/protein were found to be organic foulants regardless of their molecular weight and origin. Chemical cleaning with chlorine solution was effective in removing all inorganic foulants and most organic foulants.

Energy consumption is one of the major concerns in the current environment, not only because of the limited availability of non-renewable fuels, but also due to the high cost and the pollution generated by energy production. In general, industries consume large quantities of electricity, fuels and other types of energy. Among the industries, the chemical industry is one of the highest energy consumers because of the nature of its processes. This fact makes the chemical industry one of the best candidates for the study and evaluation of different technologies to improve the efficiency of the energy use without affecting the productivity and quality of their processes and products. This thesis analyzes the energy consumption in the chemical industry and provides recommendations to increase the energy efficiency of the critical systems utilized in this industry. Different methods to reduce the energy losses during generation and transmission, the use of waste heat for improving energy efficiency, and several analysis tools to help in evaluating the potential energy and cost savings for each facility are also discussed in this thesis. Several case studies are reviewed to demonstrate the effectiveness of the energy savings recommendations and tools presented in this investigation.

<p> Demand ever increases for clean-burning, high-efficiency, and power-dense jet engines. This demand raises the thermal requirements and stresses on fuel systems for every new generation of gas turbine engine. Fuel is used to cool subsystems such as engine oil, pumps, electronics, valves, etc. resulting in elevated fuel temperatures upstream of combustor nozzles. Carbonaceous deposits or fouling occurs if the wetted wall temperature is elevated sufficiently, especially at fuel nozzle tips where temperatures are maximized. Fouling within fuel nozzles diminish atomization performance producing incomplete combustion, instability, and polluting byproducts. Therefore, the industry seeks strategies to mitigate carbon deposition without reducing the thermal requirements placed on the fuel. Existing carbon mitigation techniques rely on coating the fuel-wetted surfaces in an inert layer via anodic oxidation, chemical vapor deposition, etc. In this proposal, we aim to investigate a novel approach: inducing the lotus effect (heterogenous wetting) along the walls of fuel passageways. The lotus effect minimizes wetting area along a liquid-solid interface using a highly ordered set of micro or nano features with weak interfacial energy resulting in the liquid only wetting the peaks of said features. We hypothesized that the combination of a chemically inert surface with reduced wetting area diminishes the opportunity for deposit to form. The mitigating effect can be enhanced by the thermal insulation provided by the vapor or gas pockets trapped between the liquid-solid interface, passively reducing the thermal loading of the fuel. As a preliminary step, we produced the lotus effect on multiple aerospace alloys such as Inconel 718, stainless steel 304, and pure titanium via electrochemical etching and surface modification. We then exposed treated tubes to fuel under fouling-favorable conditions to compare their relative deposition rates. Our results indicate that the lotus effect loses stability at pressures well below those used in practical applications. However, the electrochemical etch we developed consistently produced negligible deposit where it would typically be maximized. Depending on if the surface is etched, FAS17 (a perfluoroalkyl silane used to generate superphobicity) can act to encourage or discourage carbon deposition. We determined that the electrochemical etch or FAS17 alone may be a method to mitigate carbon deposition regardless of the wetting behavior </p>

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