Abstract
The urgent need for sustainable water purification technologies has spurred advancements in polymeric membranes, prioritizing eco-friendly fabrication and circular economy principles. This PhD thesis investigates innovative, sustainable membrane synthesis methods and their applications in liquid separation, emphasizing green chemistry and recyclability. Mechanochemical synthesis was utilized to produce Polymer of Intrinsic Microporosity (PIM-1), achieving a 1.5-fold reduction in environmental impact compared to conventional wet-chemical methods, as confirmed by life cycle assessment (LCA). Functionalization of PIM-1 with polyethyleneimine (PEI) at 650 rpm via mechanochemistry yielded PIM/PEI-650, confirmed by infrared spectroscopy, with enhanced surface area due to micro-perforations. This sorbent exhibited nearly tripled methyl blue adsorption capacity compared to pristine PIM-1, driven by abundant amine groups, and maintained excellent reusability over five cycles.Additionally, PIM-1 was reacted with hydroxyl amine and converted into amidoxime-modified PIM (AOPIM) for adsorptive membranes. The AOPIM adsorptive membrane demonstrates high flux (94.7–94.9 L m⁻² h⁻¹ bar⁻¹), low energy demand, and pH-responsive selectivity, achieving 80% rejection for anionic dyes and 99% for cationic dyes (444.2 mg g⁻¹ uptake) in single and dual-dye mixtures at high pH level.
To address end-of-life challenges, recyclable nanofibrous membranes were developed using a methacrylate copolymer with reversible Diels-Alder crosslinks, maintaining excellent oil-water separation performance (98.9–99.9% water removal) over multiple recycling cycles. However, challenges such as scalability, mechanical stability under acidic conditions, and oxidative degradation during recycling were identified.
Future directions involve optimizing mechanosynthesis for higher molecular weight polymers, exploring long-chain methacrylates for enhanced durability, and conducting pilot-scale studies to assess industrial feasibility. Comprehensive LCA and techno-economic analyses (TEA) are proposed to evaluate the environmental and economic viability of these recyclable membranes against commercial alternatives. This research highlights the transformative potential of green chemistry and circular economy principles in developing sustainable membrane technologies for efficient water purification and resource recovery, addressing global water challenges with environmentally responsible solutions.
| Date of Award | 12 Nov 2025 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Ming Xie (Supervisor) & Andy Burrows (Supervisor) |
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