Material and Process Design for High-Performance Membrane Distillation

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dc.contributor.advisorLi, Qilinen_US
dc.creatorHe, Zeen_US
dc.date.accessioned2024-05-21T15:22:54Zen_US
dc.date.created2024-05en_US
dc.date.issued2024-04-19en_US
dc.date.submittedMay 2024en_US
dc.date.updated2024-05-21T15:22:54Zen_US
dc.descriptionEMBARGO NOTE: This item is embargoed until 2030-05-01en_US
dc.description.abstractMembrane distillation (MD) is a promising desalination technology, especially for hypersaline water desalination and brine management. However, the practical application of MD is hindered by several critical issues: membrane wetting, intensive energy consumption, and limited scalability and water recovery. This dissertation explores promising strategies in membrane material design and system process innovation to resolve the challenges, thereby advancing the implementation of membrane distillation. Carbon nanomaterial composite membranes were found capable of improving the membrane distillation flux but the underlying mechanism was not yet understood. Carbon nanotube (CNT) as a typical carbon nanomaterial was incorporated into electrospun polymeric membrane for MD. The membrane properties relevant to flux performance were characterized. Electrical impedance spectrum analysis was performed to evaluate the partial wetting degree quantitively. The mitigated partial wetting attributed to the nanostructure and smaller surface pore size was found to be the main mechanism of the improved flux performance. Polydopamine (PDA) coating is a widely used method of membrane surface modification for functional materials grafting. Cracking was found to occur on PDA thin film because of the internal stress in dehydration process and the mismatch of elastic stress between PDA and substrate. The cracking led to fragmentation of membrane substrates and impaired the membrane mechanical strength, especially for microporous membranes. PDA film cracking and its unfavorable impact on the mechanical stability of the membranes could be avoided by prewetting the membranes, using a composite membrane with a support layer or a dense membrane. Photothermal membrane distillation (PMD) enjoys high energy efficiency and scalability by reversing temperature polarization in conventional MD. A few previous works achieved gained output ratio (GOR) values of >1 with multi-effect design (ME-PMD). For the first time, this work examined the effects of operating and configuration parameters on the ME-PMD performance, providing a deeper insight into the design of ME-PMD. Low velocity of intermediate effect feed promoted high permeate flux through current effect, while presenting minor impact on flux of previous effect across a wide range (0.13~9.6 mm/s). Heat and mass transfer simulation with COMSOL Multiphysics revealed this was attributed to the less heat loss in intermediate effect. The total flux and GOR increased with the number of effects, but the marginal benefits decreased when adding more effects. With a low 2nd effect feed velocity, triple-effect PMD presented a GOR almost twice single-effect. The impacts of 1st effect feed and coolant velocities were also examined. A novel spiral wound ME-PMD reactor was designed and demonstrated with remarkable membrane distillation performance due to internal heat recovery between multiple effects of feed water in parallel. A 3.5-effect spiral wound ME-PMD presented a GOR around 2.5 treating feed water of 5 g/L. The impact of various operating parameters on system performance was investigated. The total flux increased with solar irradiance and decreased with feed salinity. Lower velocity in outer effect led to higher flux in all effects. On the other hand, inner effect velocity presented less significant impact on overall flux. A second-degree response surface model was developed to establish the relationships between system performance and operating parameters. The work demonstrated that this novel cross-flow spiral wound ME-PMD reactor could provide a feasible strategy of high-performance desalination and brine management using concentrated sunlight.en_US
dc.embargo.lift2030-05-01en_US
dc.embargo.terms2030-05-01en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationHe, Ze. Material and Process Design for High-Performance Membrane Distillation. (2024). PhD diss., Rice University. https://hdl.handle.net/1911/116025en_US
dc.identifier.urihttps://hdl.handle.net/1911/116025en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectmembrane distillationen_US
dc.subjecttemperature polarizationen_US
dc.subjectwater recoveryen_US
dc.subjectscalabilityen_US
dc.subjectGORen_US
dc.subjectmembrane wettingen_US
dc.subjectpartial wettingen_US
dc.subjectcabon nanomaterialsen_US
dc.subjectphotothermal membrane distillationen_US
dc.subjectheat recoveryen_US
dc.subjectmulti-effect designen_US
dc.subjectspiral wounden_US
dc.subjectpolydopamine coatingen_US
dc.titleMaterial and Process Design for High-Performance Membrane Distillationen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentChemical and Biomolecular Engineeringen_US
thesis.degree.disciplineEngineeringen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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