Self-assembly of graphene oxide at the interface with porous polymeric films for applications in water treatment

Graphene oxide (GO)-based membranes are promising candidates for aqueous separations thanks to the fast water permeation routes in stacked GO sheets by the low-friction flow of a monolayer of water through two-dimensional capillaries formed between the layers, combined with size and electrostatic exclusion mechanisms, able to improve membrane selectivity [1]. In this study, two different strategies were investigated to produce nanostructured self-assembled GO-polymer membranes: (i) self-assembly of GO on a porous membrane to obtain composite systems and (ii) blending of GO in a polymer solution to produce mixed matrix membranes. The results highlighted the key role of polymer chemistry and surface charge on the GO self-assembly. A composite GO-polymer membrane characterized by elevated stability in water and saline solutions was developed for application in nanofiltration (NF). Moreover, a hydrophobic mixed matrix membrane was prepared by dispersion of GO in a polyvinylidene fluoride (PVDF) matrix through a green and easily scalable phase separation method [2]. The GO-PVDF membrane showed improved rejection in membrane distillation application in comparison with a PVDF polymeric membrane thanks to the combined electrostatic and barrier effect of the GO lamellas. References [1] Saoirse, D.; Dionysios, D. D.; Suresh, C. P. 2D nanostructures for water purification: graphene and beyond, Nanoscale, 2016, 8, 15115- 15131. [2] Meringolo, C.; Mastropietro, T.F.; Poerio, T.; Fontananova, E.; De Filpo, G.; Curcio, E.; Di Profio, G. ACS Sust. Chem. Engin., 2018, 6, 10069-10077. Acknowledgment This work was carried out in the framework of the project "Development of a solar powered, zero liquid discharge Integrated desalination membrane system to address the needs for water of the Mediterranean region" (IDEA-ERANETMED2-72-357, prot. MIUR N. 10912, 06/06/2016).