Customized Thin Film Composite Nanofiltration Membranes using Additive Manufacturing
Digital Document
Document
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http://hdl.handle.net/11134/20002:860727350
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Persons
Creator (cre): "Qian, Xin"
Major Advisor (mja): McCutcheon, Jeffrey
Associate Advisor (asa): Burke, Kelly
Associate Advisor (asa): Parnas, Richard
Associate Advisor (asa): Li, Baikun
Associate Advisor (asa): Ma, Anson
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Title |
Title
Title
Customized Thin Film Composite Nanofiltration Membranes using Additive Manufacturing
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Origin Information
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Parent Item
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Digital Origin |
Digital Origin
born digital
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Description |
Description
Water scarcity has been a long-lasting challenge as at least half of the human beings are still struggling with lack of clean water access. There have been many attempts to alleviate this issue by removing the contaminants in wastewater and enable water reuse. Membrane filtration has been widely recognized as one of the most impressive and economic methods for wastewater treatment such as seawater and brackish water desalination, dye removal from textile wastewater, industrial wastewater treatment. Membrane could also be used for other separations such as purification of pharmaceutical (drug) substance and oil refinery. State-of-the-art flat sheet membrane could provide decent removal of a variety of contaminant molecules based on the membrane pore size. However, conventional approaches used to fabricate these membranes, such as casting and interfacial polymerization, typically result in thick selective layers being formed that can limit membrane performance especially permeance. 3D printing technique has been a desirable innovation in various industries due to its high accuracy, precision and resolution. However, only in the recent years this revolutionary technique has gradually been applied in membrane fabrication. Chapter 2 of this thesis will provide a broad description on the previous investigations and applications of the novel membrane 3D printing techniques in making membranes and other 3D printed objects. Chapter 2 also involves the description of each 3D printing technique, their advantages and drawbacks, together with the key metrics that define the feasibility of each additive manufacturing in making membranes. The main body of Chapter 2 will focus on reviewing and discussion on previous work on 3D printed membranes as categorized by printing techniques. Additionally, the article will also include some potential challenges and expand the perspectives of this technique in future membrane manufacturing applications. In Chapter 3, we discuss the 3D printing of a key membrane component-feed spacer, which is frequently used in spiral wound elements and flat sheet modules. Chapter 3 will primarily introduce specific 3D printing methods used for spacer manufacturing, key metrics as well as providing a thorough assessment of each 3D printing technique in making spacers. These metrics will be grouped as manufacturing benefits, performance benefits and commercial viability to provide quantifiable assessment of 3D printing methods. The major part of Chapter 3 will discuss the previous literature on 3D printed spacer structures with novel geometries, configurations and their superior performance in membrane modules. Chapter 4 and 5 will focus on scientific research work of using electrospray 3D printing in making different thin film composite (TFC) membranes for nanofiltration. Chapter 4 will evaluate the use of electrospray to print thin layers of amphiphilic zwitterionic selective layers onto UF membrane substrates. Dyes with different sizes are used to probe the selectivity of these membranes while their thickness is reduced by orders of magnitude compared to casting methods. As thickness is decreased, water permeance was found to proportionally increase while dye selectivity was maintained. While it was found that a threshold minimum thickness was required to maintain selectivity for some molecules, the intrinsic permeability of the polymer films was changed as a function of thickness. Notably, one of our cured ultra-thin TFC membranes was found to exhibit a water permeance value of 205LMH/bar and a Chlorophyllin rejection at 99.67%. Interestingly, this permeance is indistinguishable from the supporting UF membrane permeance, suggesting that even higher permeance without selectivity loss is possible with more permeable support layers. In Chapter 5, a 3D printed chlorine tolerant membrane was proposed as an alternative for polyamide nanofiltration membranes. Membrane chemical robustness has been regarded as a significant factor in wastewater treatment. Compared with conventional polyamide TFC membrane, poly(epoxyether) membrane have been found to show superior chemical stability in most aggressive feed conditions. However, conventional poly(epoxyether) TFC membranes made by interfacial initialization polymerization suffered from low permeance when decent selectivity was preferred. In this chapter we evaluate the use of electrospray to print thin layers of poly(epoxyether) selective layer on UF support. The printed membranes exhibit over 50 LMH/bar water permeance and over 90% Rose Bengal rejection while still maintaining a water permeance of 27 LMH/bar and 97% Rose Bengal rejection after strong NaClO attack even art extreme pH conditions. Additionally, by post-curing the poly(epoxyether) membranes at higher temperature, we are able to greatly improve methyl orange rejection (97.6%) due to much higher crosslinking density as more epoxide monomers are polymerized into the poly(epoxyether). These results suggest that electrospray is able to generate a thin, permeable and chlorine tolerant selective layer that could also be made denser and exhibit high rejection for smaller dye molecules. In Chapter 6, we will discuss conclusion of my research findings in 3D printed zwitterionic copolymer membranes and 3D printed poly(epoxyether) membranes. The conclusion will summarize the benefits, characteristics and applications of additive manufacturing in membrane and spacer manufacturing. This chapter also provides two additional sections discussing other membranes made by additive manufacturing, its future perspectives as well as its novel contributions in chemical engineering and membrane science field.
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Genre
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Organizations
Degree granting institution (dgg): University of Connecticut
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Physical Form
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Rights Statement
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Use and Reproduction |
Use and Reproduction
These Materials are provided for educational and research purposes only.
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Note |
Note
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Degree Name |
Degree Name
Doctor of Philosophy
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Degree Level |
Degree Level
Doctoral
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Degree Discipline |
Degree Discipline
Chemical Engineering
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Local Identifier |
Local Identifier
S_34162360
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