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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.