Abstract
Two-dimensional (2D) nanosheets show promise for the development of water treatment membranes with extraordinary separation properties and the advantages of atomic thickness with micrometer-sized lateral dimensions. Stacked graphene oxide (GO)-based membranes can demonstrate unique molecular sieving properties with fast water permeation. However, improvements to the structural stability of the membranes in water to avoid problems such as swelling, disruption of the ordered GO layer and decreased rejection are crucial issues. This study reports the fabrication of stacked GO nanosheet membranes by simple vacuum filtration using triethanolamine (TEOA) as a crosslinker and mild reducing agent for improved structural stability and membrane performance. Results show that GO membranes modified with TEOA (GO-TEOA membranes) have a higher structural stability in water than unmodified GO membranes, resulting in improved salt rejection performance. Furthermore, GO-TEOA membranes show stable water permeance at applied pressures up to 9 bar with Na2SO4 rejection of 85%, suggesting the potential benefits for water treatment applications.
Highlights
Membrane separation has become an advanced technology for solving environmental and energy issues
graphene oxide (GO) nanosheet membranes were fabricated with triethanolamine (TEOA) using simple vacuum
GO nanosheet membranes were fabricated with triethanolamine (TEOA) using simple vacuum filtration
Summary
Membrane separation has become an advanced technology for solving environmental and energy issues. Nanomaterials for membranes have been extensively studied to overcome the limitations of conventional polymeric or inorganic membrane materials, for water treatment due to the high demand for clean water at low cost [1]. Common materials for nanosheets include graphene-based materials [2,3,4,5,6,7,8,9,10,11,12,13], transition metal dichalcogenides [14,15,16,17] and transition metal oxides [18,19]. GO (graphene oxide), a derivative of graphite and GO-based membranes have been extensively studied because their unique molecular sieving properties with fast water permeation, simple fabrication method as well as surface hydrophilic properties are attractive for water treatment. GO contains many oxygen functional groups, such as hydroxyl, carboxyl and Membranes 2018, 8, 130; doi:10.3390/membranes8040130 www.mdpi.com/journal/membranes
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