Author ORCID Identifier
Semester
Fall
Date of Graduation
2025
Document Type
Dissertation
Degree Type
PhD
College
Statler College of Engineering and Mineral Resources
Department
Chemical and Biomedical Engineering
Committee Chair
Oishi Sanyal
Committee Member
Cerasela Zoica Dinu
Committee Member
Fernando V. Lima
Committee Member
Konstantinos Sierros
Committee Member
John Hu
Abstract
Abstract
New Manufacturing Strategies for Advanced Membranes
Brian Leonard
This dissertation specifically focuses on two advanced membrane manufacturing methods – direct ink writing (DIW, a 3D printing method) and hollow fiber manufacturing. The DIW method was used to manufacture polysulfone membranes for liquid-based applications, while the hollow fiber membranes were used for manufacturing polyimide-derived carbon molecular sieve (CMS) membranes. While new membrane materials are developed at a constant pace with improved separation properties, manufacturing these materials into scalable formats is often overlooked in academic research. In my research, I address the topic of sustainable manufacturing by using DIW for making flat sheet polysulfone membranes via significant reduction in solvent usage. In addition, I also demonstrate the manufacturing of a high-performance rigid molecular sieve material, viz. CMS into hollow fiber formats for hydrogen separation and utilize a scalable chemical treatment method to improve the separation performance of the original membranes.
Membranes play an important role in the separation of challenging mixture situations (both liquid and gas phase) which are otherwise difficult to separate without a large energy expenditure. In recent years sustainable membrane manufacturing has received significant attention, motivated by the recent EU regulations that have banned several solvents commonly used for membrane manufacturing [1]. In the context of reduced solvent usage, additive manufacturing strategies such as DIW are perceived to play an important role and through my project, I have contributed to this by showcasing this strategy to make polysulfone membranes. In this work, I identified the importance of process parameters such as surface roughness of the underlying substrate and ambient humidity. The DIW membranes showed similar separation performance as doctor blade manufactored polysulfone membranes, when compared in terms of equivalent metrics. These membranes also demonstrated high stability when tested against high pressure and under high tangential flow conditions. The work covered in this dissertation thus focuses on a novel manufacturing strategy and demonstrates its effectiveness both in terms of intrinsic separation performance, as well as its scalability, reproducibility and performance under realistic testing conditions.
Another important aspect of manufacturing is to ensure appropriate translation of high performance membrane materials into scalable formats such as hollow fibers. Many novel materials based on polymers, hybrid (mixed-matrix) and rigid molecular sieves have been developed for a range of applications; however, few studies focus on their corresponding hollow fiber formats. In this context, the 2nd part of my dissertation demonstrates the development of novel carbon molecular sieve (CMS) membranes for purified H2 production from a biomass derived syngas mixture. A novel chemical diamine based selective layer modification technique was introduced in this part of my work, which led to improvements in H2 productivity in comparison to unmodified CMS membranes. The results were evaluated in terms of diffusion and sorption coefficients and pore size distribution, and it was concluded that this chemical treatment specifically led to increase in diffusion coefficients. This rise in the diffusion coefficient was attributed to the disruption of hyperskin – a dense ultramicroporous portion located on top of the selective layer of CMS membranes, that results in lower than expected productivities in CMS membranes. This hyperskin has been identified and characterized in prior literature, and its presence has been confirmed with diverse characterization techniques; however, methods to eliminate it have not been reported. In my dissertation, I have provided a detailed vision on how the diamine based chemical treatment of CMS hollow fibers leads to preventing the hyperskin from forming. My future work would involve demonstrating a proof of concept of hollow fiber development with the 3D printing technique, therefore combining the two sections of my dissertation research.
Recommended Citation
Leonard, Brian Curtis, "New Manufacturing Strategies for Advanced Membranes" (2025). Graduate Theses, Dissertations, and Problem Reports. 13150.
https://researchrepository.wvu.edu/etd/13150