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- Ismail, Norafiqah, et al.
(författare)
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Dibasic esters as green solvents for PVDF membrane preparation
- 2023
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Ingår i: Green Chemistry. - : Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 25:18, s. 7259-7272
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Tidskriftsartikel (refereegranskat)abstract
- Solvent toxicity is a major barrier to sustainable fabrication of polymeric membranes. This study introduces three dibasic esters (DBEs) as alternative membrane fabrication solvents that are biodegradable, non-carcinogenic, non-corrosive, and non-hazardous. The use of DBEs in fabrication processes shifts the monotectic point in the phase diagram of PVDF/solvent systems towards higher polymer concentrations, enabling membrane formation by liquid–liquid phase inversion to produce a bicontinuous structure that confers outstanding performance. The best-performing membrane prepared in this way had an exceptional flux of 42.40 kg m−2 h−1 and a high rejection rate (>99%) in the decontamination of synthetic nuclear wastewater. Compared to membranes prepared previously using toxic and non-toxic solvents, membranes fabricated in DBEs exhibited superior mechanical performance due to their bicontinuous structure, which effectively distributes external forces throughout the membrane. Moreover, DBEs are cheaper than toxic conventional solvents and are readily available in bulk, making them attractive options for industrial-scale membrane production.
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| 2. |
- Ismail, Norafiqah, 1989-
(författare)
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Sustainable membrane fabrication using greener solvents
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Technologies based on polymeric membranes have diverse applications in purification, desalination, and decontamination processes. However, current membrane production techniques are neither sustainable nor environmentally benign. A Life-Cycle Assessment (LCA) was conducted to determine how the choice of membrane polymer (fossil-based or bio-based), the solvent (toxic or green), and the energy source used in membrane fabrication affect their environmental impacts. The results showed that solvent toxicity is the main obstacle to sustainable membrane production. The harmful environmental effects of current membrane production processes are largely due to the use of toxic solvents, particularly polar aprotic solvents such as N-methyl pyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc). It was also found that replacing these solvents with the green solvent, ethylene carbonate (EC), would reduce the environmental impact of membrane production by up to 35%. Developing sustainable membrane fabrication techniques using green solvents could thus be highly beneficial.In this thesis, three different pathways were proposed to address sustainability issues in membrane production identified in the LCA study. First, it prompted an investigation into the viability of utilizing three environmentally friendly cyclic carbonate solvents: EC; propylene carbonate (PC); and butylene carbonate (BC) for the production of polyvinylidene fluoride (PVDF) membranes. These solvents are biobased, biodegradable, inexpensive, and readily available on large scales. The study aimed to examine the influence of solvent structure on membrane morphology, polymorphism, and separation performance. It provided valuable insights into the mechanisms governing the formation of pure β-phase PVDF membranes.Non-ionic deep eutectic solvents (NIDES) are a sub-class of ionic liquids that can be synthesized inexpensively using simple heating processes with no pre- or post-treatment. As such, they could be attractive alternative solvents for membrane fabrication. Three NIDES were synthesized and used to dissolve PVDF: N-methylacetamide-acetamide (DES-1); N-methyl acetamide-N-methyl urea (DES-2); and N-methyl acetamide-N,N’-dimethyl urea (DES-3). The favorable performance of the obtained membranes together with the low cost, low toxicity, and simple large-scale synthesis of NIDES makes this an attractive approach for membrane production. Finally, three Dibasic Esters (DBEs) namely dimethyl succinate (DMS), dimethyl glutarate (DMG) and dimethyl adipate (DMA) were introduced as alternative green solvents for PVDF membrane production. DBEs have several desirable properties including biodegradability, non-carcinogenicity, non-corrosiveness, and non-hazardousness. Furthermore, these DBEs are not only more economical compared to hazardous solvents but are also easily accessible in significant quantities, thus increasing their suitability for large-scale industrial membrane manufacturing. Hence, we conducted an assessment of the morphology, properties, and performance of DBEs as a potential solvent alternative for membrane production. To conclude, this thesis provides an improved and advanced understanding of sustainable approaches in polymeric membrane production. By investigating different aspects such as solvent choices and introducing alternative solvents, the research contributes valuable insights to the field and promotes the development of more environmentally friendly and sustainable environment membrane manufacturing processes.
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| 3. |
- Ma, Wenzhong, et al.
(författare)
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Membrane formation by thermally induced phase separation : materials, involved parameters, modeling, current efforts and future directions
- 2023
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Ingår i: Journal of Membrane Science. - : Elsevier. - 0376-7388 .- 1873-3123. ; 669
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Tidskriftsartikel (refereegranskat)abstract
- Thermally-induced phase separation (TIPS) is one of the most popular methods considered for membrane preparation. Since its introduction by Castro in 1981, there has been significant progress in understanding, controlling, and implementing TIPS. This review provides a critical and integrative evaluation of the literature in this area that effectively defines the current state-of-the-art. It begins with an overview of the basic principles of TIPS and the used materials (polymers, diluents and additives) paying particular attention to the sustainability of the TIPS process. The subsequent sections examine the parameters affecting the outcome of TIPS technique, the role of mass transfer, and methods for modeling TIPS. This is followed by a discussion of current and potential applications of TIPS membranes. Finally, the review concludes with a discussion of likely future developments and prospects for the TIPS process.
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