Ultrathin Graphene Membrane Ion Separation
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Solution Overview
Problem
Current technologies lack the capability to fabricate ultrathin graphene-based membranes that can selectively remove ions from water, particularly for desalination and other industrial processes, due to the absence of membranes with sub-nanometer pore sizes.
Innovation Solution
Development of ultrathin graphene-based membranes with tunable pore sizes ranging from 0.3 nm to 20 nm, formed using graphene-oxide layers and optional interlayer locking molecules, allowing for high selectivity in ion separation by controlling the deposition conditions and structure of graphene oxide flakes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional membrane filtration is used to remove ions from water, then ion removal capability is achieved, but membrane thickness is large and energy consumption is high
Solution Approach 1:
The patent employs ultrathin graphene oxide membranes with thickness of 2-20 nm, which are flexible two-dimensional films that provide exceptional ion rejection while maintaining high water permeability. The atomic-scale thickness dramatically reduces the transport path for water molecules, lowering energy consumption compared to conventional thick membranes
Solution Approach 2:
The graphene oxide membranes possess controlled porous structures with interlayer spacing that can be tuned to allow water molecules to pass through while blocking larger ion species. This porous architecture at the nanoscale enables selective ion removal with minimal energy input
2Manufacturing precision
If membrane filtration is used to remove ions from water, then ion removal is achieved, but selectivity is insufficient
Solution Approach 1:
The graphene oxide membranes exhibit local quality variations through controlled oxidation degrees and functional group distributions across the membrane structure. This creates regions with different pore sizes and chemical properties that can selectively interact with specific ions, enhancing separation selectivity
Solution Approach 2:
The membranes are constructed as composite structures combining graphene oxide layers with specific functional groups and interlayer spacers. This composite architecture integrates size exclusion, charge repulsion, and chemical affinity mechanisms to achieve high ion selectivity
3Use of energy by moving object
If ultrathin membranes are fabricated to reduce energy consumption, then energy efficiency is improved, but manufacturing precision and defect control become difficult
Solution Approach 1:
The manufacturing process employs preliminary oxidation of graphite to form graphene oxide flakes before assembling them into membranes. This preliminary action creates uniformly spaced oxygen functional groups that act as spacers, ensuring consistent interlayer distances and reducing defects in the final ultrathin membrane structure
Solution Approach 2:
Interlayer spacer molecules are introduced as intermediaries between graphene oxide layers during membrane fabrication. These spacers control the vertical spacing and prevent direct stacking, ensuring uniform pore structures and reducing manufacturing defects in the ultrathin membranes
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 membranes achieve high selectivity and flux in ion removal, enabling efficient desalination and water purification by allowing water molecules to pass through while preventing larger ions and molecules from passing through, potentially reducing energy costs in industrial processes.
Implementation Method 1
allowing water molecules to pass through while preventing larger ions and molecules from passing through
Implementation Method 2
each graphene-oxide flake having a planar graphene structure with oxygen moieties extending therefrom
Implementation Method 3
water can be passed through the graphene-based membrane
Data Source
AI summary
A graphene-based membrane, along with its methods of formation and use, is provided. The graphene membrane includes at least two graphene-oxide layers. Each graphene-oxide layer has a plurality of graphene-oxide flakes, with each graphene-oxide flake having a planar graphene structure with oxygen moieties extending therefrom. The graphene-based membrane can have a thickness of about 2 nm to about 20 nm. Such a graphene-based membrane can be utilized to remove ions from water.