Matching Items (24)
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- All Subjects: chemical engineering
- Creators: Lind, Mary Laura
Description
Styrene, a component of many rubber products, is currently synthesized from petroleum in a highly energy-intensive process. The Nielsen Laboratory at Arizona State has demonstrated a biochemical pathway by which E. coli can be engineered to produce styrene from the amino acid phenylalanine, which E. coli naturally synthesizes from glucose. However, styrene becomes toxic to E. coli above concentrations of 300 mg/L, severely limiting the large-scale applicability of the pathway. Thus, styrene must somehow be continuously removed from the system to facilitate higher yields and for the purposes of scale-up. The separation methods of pervaporation and solvent extraction were investigated to this end. Furthermore, the styrene pathway was extended by one step to produce styrene oxide, which is less volatile than styrene and theoretically simpler to recover. Adsorption of styrene oxide using the hydrophobic resin L-493 was attempted in order to improve the yield of styrene oxide and to provide additional proof of concept that the flux through the styrene pathway can be increased. The maximum styrene titer achieved was 1.2 g/L using the method of solvent extraction, but this yield was only possible when additional phenylalanine was supplemented to the system.
ContributorsMcDaniel, Matthew Cary (Author) / Nielsen, David (Thesis director) / Lind, Mary Laura (Committee member) / McKenna, Rebekah (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor) / Chemical Engineering Program (Contributor)
Created2013-05
Description
One of the grand challenges of engineering is to provide access to clean water because it is predicted that by 2025 more than two thirds of the world’s population will face severe water shortages. To combat this global issue, our lab focuses on creating a novel composite membrane to recover potable water from waste. For use as the water-selective component in this membrane design Linde Type A zeolites were synthesized for optimal size without the use of a template. Current template-free synthesis of zeolite LTA produces particles that are too large for our application therefore the particle size was reduced in this study to reduce fouling of the membrane while also investigating the nanoparticle synthesis mechanisms. The time and temperature of the reaction and the aging of the precursor gel were systematically modified and observed to determine the optimal conditions for producing the particles. Scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray analysis were used for characterization. Sub-micron sized particles were synthesized at 2 weeks aging time at -8°C with an average size of 0.6 micrometers, a size suitable for our membrane. There is a limit to the posterity and uniformity of particles produced from modifying the reaction time and temperature. All results follow general crystallization theory. Longer aging produced smaller particles, consistent with nucleation theory. Spinodal decomposition is predicted to affect nucleation clustering during aging due to the temperature scheme. Efforts will be made to shorten the effective aging time and these particles will eventually be incorporated into our mixed matrix osmosis membrane.
ContributorsKing, Julia Ann (Author) / Lind, Mary Laura (Thesis director) / Durgun, Pinar Cay (Committee member) / Chemical Engineering Program (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Freshwater as the resource for the survival of humans and all lives on earth is very precious but scarce. The shortage of the original freshwater resources and the interfering activities by human and other natural factors form this issue together. To reduce the water supply pressure and deterioration of freshwater systems (for example, river, wetland, and groundwater), the quantity-increase and the quality-increase strategies should be implemented at the same time. Therefore, corresponding membrane technologies have been developed to achieve water purification with high efficiency and low cost. For desalinating seawater and other types of saline water, pervaporation has been proved that has the potential to complete desalination with salt rejection rate over 99 % when dealing with high salinity water that reverse osmosis (RO) cannot handle. In this dissertation, except the discussion of commonly used materials to synthesize pervaporation membranes, two types of novel pervaporation desalination membranes (nanophotonic-enhanced membrane and free-standing sulfonated membrane) have been presented and discussed. The novel membranes were tested to see the potential of pervaporation to desalinate seawater and saline water with more complex ionic composition, and the possibility of achieving zero liquid discharge in the desalination field when having pervaporation as the assistance. For mitigating polluted water that is caused by human activities, especially agricultural activities, electrodialysis is an effective method to remove specific ions from water, and it does not require extra chemical cost or regeneration. A type of anion exchange membranes inspired by ion exchange resins was synthesized and tested, and the performance on nitrate removal has been evaluated in this dissertation.
ContributorsLi, Yusi (Author) / Lind, Mary Laura (Thesis advisor) / Perreault, Francois (Thesis advisor) / Forzani, Erica (Committee member) / Seo, S. Eileen (Committee member) / Walker, W. Shane (Committee member) / Arizona State University (Publisher)
Created2023
Description
Membrane based technology is one of the principal methods currently in widespread use to address the global water shortage. Pervaporation desalination is a membrane technology for water purification currently under investigation as a method for processing reverse osmosis concentrates or for stand-alone applications. Concentration polarization is a potential problem in any membrane separation. In desalination concentration polarization can lead to reduced water flux, increased propensity for membrane scaling, and decreased quality of the product water. Quantifying concentration polarization is important because reducing concentration polarization requires increased capital and operating costs in the form of feed spacers and high feed flow velocities. The prevalent methods for quantifying concentration polarization are based on the steady state thin film boundary layer theory. Baker’s method, previously used for pervaporation volatile organic compound separations but not desalination, was successfully applied to data from five previously published pervaporation desalination studies. Further investigation suggests that Baker’s method may not have wide applicability in desalination. Instead, the limitations of the steady state assumption were exposed. Additionally, preliminary results of nanophotonic enhancement of pervaporation membranes were found to produce significant flux enhancement. A novel theory on the mitigation of concentration polarization by the photothermal effect was discussed.
ContributorsMann, Stewart, Ph.D (Author) / Lind, Mary Laura (Thesis advisor) / Walker, Shane (Committee member) / Green, Matthew (Committee member) / Forzani, Erica (Committee member) / Emady, Heather (Committee member) / Arizona State University (Publisher)
Created2019