Toward a More Sustainable Approach In Membrane Fabrication

Alberto Figoli
Institute on Membrane Technology, CNR-ITM, Rende, Italy 

Environmental protection and climate change are current issues at the heart of global economic growth. The awareness of the real risks connected with industrial membrane production sector has been the push towards the search of new, more sustainable, solvents and raw materials [1]. The 5th principle of Green Chemistry encourages the use of safer solvents and auxiliaries [2]. Solvents are the most common example of auxiliary substances for membrane preparation via phase inversion. They are needed for dissolving the selected polymer and their chemical-physical properties strongly influence the membrane formation too.
Among the most widely used solvents, N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMAc) and N-methyl pyrrolidone (NMP), represent an excellent choice for dissolving sulfones polymers. However, since they are classified as highly reprotoxic and developmental harmful, their use should be avoided whenever possible. In this context, the use of alternative, less-toxic, diluents for making polymeric membranes open new perspectives for the sustainable membrane fabrication. Herein, case studies on the flat sheet membrane production via Non-solvent- coupled with Vapor- Induced Phase Inversion using different innovative non-toxic solvents, such as Dimethyl isosorbide (DMI) or Cyrene are presented [3-4]. These solvents are completely miscible with water and alcohols; their high boiling point make them a favorable alternative for dissolving fluoropolymers, such as polyether sulfone (PES) by using different coagulation bath. The possibility of tuning the morphology and pore size of the polymeric membranes produced by using these polymers will be reported too.