Anion Exchange Membrane Quaternization Cross-Linking Resistivity
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Solution Overview
Problem
Current ion exchange membranes used in electrochemical desalination and water treatment systems face challenges such as high electrical resistance, low permselectivity, and high energy consumption, making them inefficient and costly for large-scale seawater desalination and water purification processes.
Innovation Solution
A method for fabricating homogenous ion exchange membranes using a polymeric microporous substrate filled with reactive monomers, where a tertiary amine monomer is quaternized and then cross-linked with a cross-linking agent to form a membrane with enhanced electrochemical properties, including low resistivity and high permselectivity, allowing for efficient ion exchange and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional ion exchange membranes are used, then basic ion exchange function is provided, but electrical resistance is high and energy consumption is high
Solution Approach 1:
The patent changes the chemical parameters of the membrane by introducing quaternized ammonium groups and optimizing the cross-linking density. This modifies the electrical properties of the membrane, reducing electrical resistance from conventional high values to below 1.5 Ohm-cm², thereby reducing energy consumption in electrochemical processes
Solution Approach 2:
The patent creates a composite membrane structure combining a polymeric microporous substrate with a cross-linked anion exchange polymeric layer. This composite structure integrates the mechanical support function of the substrate with the ion exchange functionality of the polymeric layer, achieving both structural integrity and low electrical resistance
2Productivity
If membrane thickness is increased to increase membrane area per unit volume, then productivity is improved, but electrical resistance increases
Solution Approach 1:
The patent optimizes the thickness parameter of the membrane to a specific range that balances surface area and electrical resistance. By controlling the thickness and optimizing the cross-linking density, the membrane achieves low electrical resistance despite increased thickness, enabling higher productivity through increased membrane area per unit volume
3Reliability
If cross-linking density is increased to improve membrane stability, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates the cross-linking agent and initiator into the monomer solution before casting, so that cross-linking occurs in-situ during the membrane formation process. This preliminary preparation eliminates the need for separate cross-linking steps, reducing manufacturing complexity while achieving the desired cross-linking density and membrane stability
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 resulting membranes exhibit improved electrochemical properties with resistivity below 1.5 Ohm-cm² and permselectivity above 95%, enabling more efficient and cost-effective electrochemical separation processes, including seawater desalination with reduced energy consumption and increased membrane area per unit volume.
Implementation Method 1
mixing a tertiary amine monomer with a quaternization agent to produce a functional monomer
Implementation Method 2
mixing a cross-linking agent and a solvent with the functional monomer to form a monomeric solution, and casting the monomeric solution on a polymeric microporous substrate to form the anion exchange membrane
Implementation Method 3
an anion exchange membrane may comprise a polymeric microporous substrate, and a cross-linked anion exchange polymeric layer on the substrate, the membrane having a resistivity of less than about 1.5 Ohm-cm 2
Data Source
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AI summary
Anion exchange membranes may include a polymeric microporous substrate and a cross-linked anion exchange polymeric layer on the substrate. Anion exchange membranes may have a resistivity of less than about 1.5 Ohm-cm2 and an apparent permselectivity of at least about 95%. The anion exchange membranes may be produced by a unique, two step process.