Thin-film composite hollow fiber membranes incorporated with graphene oxide in polyethersulfone support layers for enhanced osmotic power density

Abstract

This study focused on the development of pressure retarded osmosis (PRO) thin film composite (TFC) membranes for enhanced osmotic power using hollow fiber polyethersulfone (PES) support structure modified by incorporating hydrophilic graphene oxide (GO) nanosheets. The GO loadings in the hollow fiber substrates were varied to improve water flux performances without compromising the mechanical strength. GO embedded (≤0.2 wt%) PES hollow fiber supports revealed noticeable improvements in pure water permeability, improved structural morphologies, as well as the hydrophilicity within the support layer, without deteriorating the mechanical properties. The GO (0.2 wt%)-incorporated TFC-PRO membrane appeared to have an initial PRO flux (without any applied pressure) of 43.74 L m -2 h -1 , lower specific reverse salt flux of 0.04 g L -1 and structural parameter (S) of 522 µm, significantly better than the control membrane. The maximum power density of 14.6 W m -2 was achieved at an operating pressure of 16.5 bar under the condition of DI water and 1 M NaCl as feed and draw solutions, respectively. The results obtained in this study indicate that modification of PRO hollow fiber support layer by incorporating nanoparticles such as GO nanosheet can be a useful tool to improve the PRO performance.

Graphene Oxide Incorporated Polysulfone Substrate for Flat Sheet Thin Film Nanocomposite Pressure Retarded Osmosis Membrane

“…The fast exchange rate process will lead to an extended porosity as well as changes in the structure of the macrovoids. However, with the addition of more GO (0.5 and 1.0 wt%), the sponge-like structure appeared as the higher viscosity of the dope solution decreased the phase separation rate which might otherwise have retarded the demixing process between the solvent and the non-solvent [ 17 , 23 ]. Hence, the morphology of TFN membranes was found to depend significantly on the amount of GO added.…”

“…Incorporation of hydrophilic nanomaterials into the polymeric membranes (skin layer or/and substrate layer) led to a new generation of TFC membranes called thin film nanocomposite (TFN) membranes. This includes nanomaterials such as modified carbon nanotubes [ 11 , 12 , 13 ], covalent organic framework [ 14 ], zeolites [ 15 , 16 ] and graphene oxide (GO) [ 17 , 18 ]. Due to the enhanced hydrophilicity, structural parameter, water flux and mechanical properties that lowered the ICP phenomenon, an excellent TFC PRO performance was achieved [ 18 ].…”

“…Their excellent high surface-area-to-volume ratios would promote efficient interaction with the polymer matrix in a mixed matrix membrane (MMM) [ 27 , 28 ]. Park et al [ 17 ] synthesised a TFN hollow fibre PRO membrane with optimum GO loading of 0.2 wt%. They achieved a high water flux of 43.74 Lm −2 h −1 , and the membrane withstood pressure up to 16.5 bar.…”

Generation of Osmotic Power from Membrane Technology

“…They use bismuth oxychloride (BiOCl) as anionic and hexacyanoferrate (CuHCF) as a cationic electrode for the production of the energy density of 8.0 J m À2 with a 59.0 mW/m 2 as an average power density. TFC membranes with high power density were developed by Park et al [54]. They developed the mixed-matrix PES/graphene oxide (GO) hollow fiber support membrane and achieved 14.6 W/m 2 power density with 0.2 wt% added graphene oxide.…”

The Need for Accurate Osmotic Pressure and Mass Transfer Resistances in Modeling Osmotically Driven Membrane Processes

“…With the increasing application of hollow-fiber modules, several studies have numerically evaluated and optimized scaled-up modules [ 15 , 16 , 23 , 24 , 25 ]. In the last decade, many experiments have been performed on the nanocomposite (used graphene oxide, nanotube, carbon quantum or other nanomaterial) membranes [ 26 , 27 , 28 , 29 , 30 , 31 ], which may be the harbinger of the next generation of membranes [ 16 ].…”