Material synthesis requires an enormous amount of organic solvents which leads to huge environmental burdens. Being so, the necessity to utilize non-toxic chemicals is of growing interest in the global market. Harnessing a green fabrication strategy could be a sustainable remedy. Herein, life cycle assessment (LCA) and techno-economic assessment (TEA) using a cradle-to-gate approach to select the green synthesis route for the production of main components in mixed matrix membranes such as polymer and fillers were studied. Five representative synthesis routes of polymers of intrinsic microporosity (PIM-1) and fillers such as UiO-66-NH2 (UiO: University of Oslo) were conducted. Our findings revealed that the tetrachloroterephthalonitrile (TCTPN) synthesized PIM-1 using a novel approach (e.g., P5-Novel synthesis) and solvent-free synthesized UiO-66-NH2 (e.g., U5-Solvent-free) demonstrated the least environmental impact and are most economically feasible. The environmental burden and cost of PIM-1 synthesized by P5-Novel synthesis route decreased by 50 % and 15 %, respectively, while that of UiO-66-NH2 produced via U5-Solvent-free route reduced by 89 % and 52 %, respectively. Additionally, solvent reduction was found to have an apparent effect on cost-saving, whereby the production cost declined 13 % with a 30 % solvent reduction. Alleviation of environmental burdens could also be found through recovering solvents or substituting with a greener alternative (e.g., water). The fundamentals gained on the environmental impacts and economic feasibility of PIM-1 and UiO-66-NH2 production from this LCA-TEA study may provide a preliminary evaluation for the development of green and sustainable materials.
The aggravation of environmental problems such as water scarcity and air pollution has called upon the need for a sustainable solution globally. Membrane technology, owing to its simplicity, sustainability, and cost-effectiveness, has emerged as one of the favorable technologies for water and air purification. Among all of the membrane configurations, hollow fiber membranes hold promise due to their outstanding packing density and ease of module assembly. Herein, this review systematically outlines the fundamentals of hollow fiber membranes, which comprise the structural analyses and phase inversion mechanism. Furthermore, illustrations of the latest advances in the fabrication of organic, inorganic, and composite hollow fiber membranes are presented. Key findings on the utilization of hollow fiber membranes in microfiltration (MF), nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), pervaporation, gas and vapor separation, membrane distillation, and membrane contactor are also reported. Moreover, the applications in nuclear waste treatment and biomedical fields such as hemodialysis and drug delivery are emphasized. Subsequently, the emerging R&D areas, precisely on green fabrication and modification techniques as well as sustainable materials for hollow fiber membranes, are highlighted. Last but not least, this review offers invigorating perspectives on the future directions for the design of next-generation hollow fiber membranes for various applications. As such, the comprehensive and critical insights gained in this review are anticipated to provide a new research doorway to stimulate the future development and optimization of hollow fiber membranes.