Crosslinked Graphene Oxide Membrane for Water Desalination
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Solution Overview
Problem
Current reverse osmosis membranes for water desalination and treatment, primarily using thin-film composite configurations, face limitations in energy efficiency due to their thickness and hydrophobic nature, necessitating the development of thinner, more hydrophilic membranes with improved water flux and mechanical stability.
Innovation Solution
The development of graphene oxide (GO) based multilayer membranes, crosslinked with specific water-soluble crosslinkers, which are pretreated with dopamine and coated to achieve a thickness of 10nm to 50nm, enhancing water permeability and mechanical strength while being environmentally friendly and cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional thin-film composite RO membranes are used, then salt rejection rate is excellent, but energy efficiency is poor due to thickness and hydrophobic nature
Solution Approach 1:
The patent employs ultrathin graphene oxide membranes (10-50 nm) as the selective layer, replacing the conventional thicker polyamide layer. This extreme thinning reduces transport resistance while maintaining selectivity, directly addressing the energy efficiency problem. The GO sheets are assembled into a continuous ultrathin film that serves as both the selective and structural layer.
Solution Approach 2:
The patent utilizes the inherent porosity and interlayer spacing of graphene oxide membranes to enable water transport. The oxidized graphene structure creates channels that allow water permeation while blocking salts, achieving high water flux without requiring thick membrane structures. The porous nature of GO at the nanoscale provides the necessary permeability.
2Productivity
If membrane thickness is reduced to improve water flux, then water permeability increases, but mechanical stability deteriorates
Solution Approach 1:
The patent creates a composite structure by integrating ultrathin graphene oxide membranes with a porous support substrate. The GO layer provides selectivity and high water flux, while the underlying porous support (such as polysulfone or polyethersulfone) provides mechanical strength and structural stability. This composite architecture allows the membrane to be both thin and mechanically robust.
Solution Approach 2:
The ultrathin GO membrane (10-50 nm) acts as a flexible selective shell that is deposited on the rigid porous support. This thin film configuration maximizes water permeability while the support structure compensates for the mechanical weakness of the thin selective layer, solving the stability-flux tradeoff.
3Productivity
If conventional polyamide selective layers are used, then salt rejection is excellent, but hydrophobic nature reduces water flux
Solution Approach 1:
The patent changes the chemical composition and surface properties of the selective layer from hydrophobic polyamide to hydrophilic graphene oxide. The oxidation of graphene introduces oxygen-containing functional groups (hydroxyl, carboxyl, epoxy groups) that make the membrane surface hydrophilic, enhancing water affinity and flux while maintaining salt rejection capability.
Solution Approach 2:
The graphene oxide membrane's porous structure at the nanoscale, with interlayer spacing optimized for water transport, provides high water permeability. The porous network allows rapid water passage through capillary forces and reduced tortuosity, overcoming the limitations of dense hydrophobic polyamide layers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The GO-based membranes exhibit improved water flux and salt rejection capabilities, increasing energy efficiency and water recovery in desalination processes, while being more durable and environmentally sustainable.
Implementation Method 1
the GO composite layer is crosslinked by a crosslinker comprising a compound of Formula 2
Implementation Method 2
a water permeable membrane comprising: a porous support; and a composite, which is in fluid communication with the support, comprising a crosslinked graphene oxide (GO) composite layer
Implementation Method 3
The GO-based membranes exhibit improved water flux and salt rejection capabilities
Data Source
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AI summary
Described herein is a crosslinked graphene based composite membrane that provides selective resistance to fluids solutes while providing water permeability, such as a selectively permeable membrane comprising a crosslinked graphene with a polyvinyl alcohol and silica-nanoparticle layer that can provide enhanced water separation. Also described herein are methods for making such membranes and methods of using the membranes for dehydrating or removing solutes from water.