Understanding the role of substrates on thin film composite membranes: A green solvent approach with TamiSolve® NxG

The application of thin film composite (TFC) has emerged in aqueous and organic solvent-based membrane separation. However, the fabrication of TFC membrane requires abundant toxic and hazardous solvents, resulting in a process that is not completely green. For the first time, we report here using TamiSolve® NxG as a green solvent for the preparation of polyethersulfone (PESU) TFC membranes via nonsolvent induced phase separation. The feasibility study of using TamiSolve® NxG as a solvent for PESU membrane fabrication was evaluated by Hansen solubility parameters, ternary phase diagram, physical properties and toxicity. Besides, the impact of substrates on the separation performance of TFC membranes was investigated from the aspects of the morphology, thickness, porosity, pore size, hydrophilicity and pure water permeability (PWP). The substrates with different pore sizes were prepared while the TFC membranes demonstrated a promising separation performance with PWP and NaCl rejections of 0.64–3.54 LMH/bar and 91.4 %–94.1%, respectively. It was found that the pore size and hydrophilicity of the substrates play key roles in determining the surface morphology of TFC, which influences PWP. The fundamentals gained from this study may facilitate the development of TFC membranes using green solvents towards a sustainable membrane fabrication process.