Novel water resistant GO supported membranes: experimental preparation and theoretical investigations

Introduction/Purpose: Graphene oxide (GO) membranes are one of the emerging nano-building materials for the preparation of novel separation membrane owing to its distinct two-dimensional (2D) and single-atomic-thick structure, high mechanical strength and easy accessibility [1]. However, GO membrane supported on mechanical support for high-pressure application are necessary. Herein, we explore the potential of GO resistant membranes for water desalination combining experiments and computationa studies. Novel water separation membranes were prepared and characterized using stacked GO nanosheets deposited on different polymeric supports. Molecular dynamics (MD) simulations were used to exploit their performances in aqueous environment. Methods: Self-assembling of GO layers on several commercial or laboratory made polymeric porous membranes, was investigated. MD simulations were performed using GROMACS, [2] GO was modeled using the CHARMM [3] force field. Results: The stacked GO membranes. The stability of GO membrane supported, that may suffer from instability in the water due to the high hydrophilicity of GO sheets, is influenced by the different polymeric material, by the interlayer distance and nanopore connectivity [4]. The results obtained highlighted the key role of support chemistry and surface charge on the GO self assembly. Moreover, the GO deposition conditions influenced the structural properties of the GO/polymer composites. At theoretical level, the change in membrane interlayer distance distribution, water connectivity and water diffusivity was quantified. Conclusions: Understanding the relationship membrane composition / structure is critical for optimizing the performance of membrane separations for water desalination. Experimental and theoretical investigations gave insights about the effect of polymeric support, interlayer distance, nanopore connectivity and membrane stability. The outputs obtained can contribute in relevant way to the design and optimization of novel GO membranes for aqueous separations. Acknowledgment We acknowledge 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) Selected references Ma, J.; Ping, D.; Dong, X. Recent Developments of Graphene Oxide-Based Membranes: A Review, Membranes, 7 (2017) 52 (1-29) Van der Spoel, D.; Lindahl, E.; Hess, B.; Groenhof, G.; Mark, A. E.; Berendsen, H. J. C. GROMACS: Fast, Flexible, and Free. J. Comput. Chem., 26 (2005) 1701-1718. Vanommeslaeghe, K.; Hatcher, E.; Acharya, C.; Kundu, S.; Zhong, S.; Shim, J.; Darian, E.; Guvench, O.; Lopes, P.; Vorobyov, I.; MacKerell, A. D. CHARMM General Force Field: A Force Field for Drug-Like Molecules Compatible with the CHARMM All-Atom Additive Biological Force Fields. J. Comput. Chem., 31 (2010) 671-690. Williams, C. D.; Carbone, P.; Siperstein, F. R. In Silico Design and Characterization of Graphene Oxide Membranes with Variable Water Content and Flake Oxygen Content, ACS Nano, Just Accepted DOI: 10.1021/acsnano.8b07573