Dual-Membrane On-Line Generator for High-Purity Eluent
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Solution Overview
Problem
Existing dual-membrane electrodialytic eluent generators face challenges in producing high-purity alkali or acid solutions due to instability of anion exchange membranes in strong alkali solutions and limited pressure resistance, making them unsuitable for high-pressure chromatography systems and capable of only generating solutions within a narrow concentration range.
Innovation Solution
A dual-membrane on-line generator employing a sandwich structure with a cation exchange membrane, a bipolar membrane, and another cation exchange membrane, or an anion exchange membrane, a bipolar membrane, and another anion exchange membrane, which isolates the eluent channel from regeneration liquid channels, allowing for directional ion migration under an electric field to produce high-purity alkali or acid solutions without electrolytic gas interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dual-membrane structure with anion exchange membrane is used to isolate eluent channel from regeneration liquid channels, then electrolytic gas does not enter the eluent channel, but the anion exchange membrane has unstable performance in alkali solution and cannot produce high-purity alkali solution
Solution Approach 1:
The patent changes the membrane configuration parameter from traditional dual-membrane (cation + anion) to a structure using only cation exchange membranes in the eluent channel. This parameter change allows the system to produce high-purity alkali solutions by eliminating the unstable anion exchange membrane from the alkali generation zone while maintaining the dual-membrane isolation structure's ability to prevent electrolytic gas contamination.
2Stress or pressure
If conventional dual-membrane electrodialytic eluent generator is used, then electrolytic gas is kept out of eluent channel, but the device has limited pressure resistance and cannot withstand chromatographic system pressure
Solution Approach 1:
The patent employs composite material construction for the cell body and membrane assembly, combining robust pressure-resistant materials with selective ion-exchange membranes. This allows the device to withstand high chromatographic system pressures while maintaining solution purity through the dual-membrane isolation structure that prevents electrolytic gas from entering the eluent channel.
3Device complexity
If single-membrane structure is used with electrode in eluent channel, then device complexity is reduced, but electrolytic gas enters eluent channel and interferes with downstream analysis system
Solution Approach 1:
The patent segments the generator into distinct functional zones separated by dual membranes: regeneration liquid channels isolated from the eluent channel. This segmentation allows electrodes to be positioned in regeneration channels without their generated electrolytic gas contaminating the eluent channel, thus reducing device complexity while eliminating harmful gas interference through spatial separation.
4Reliability
If manual preparation method is used for high-purity alkali solution, then ease of operation is reduced, but solution purity cannot be maintained due to absorption of carbon dioxide from air
Solution Approach 1:
The patent implements self-service through automated on-line generation of high-purity alkali solutions using electrodialysis. The system automatically produces fresh high-purity KOH solution by directing potassium ions through cation exchange membranes into the eluent channel, eliminating manual preparation steps and preventing atmospheric CO2 contamination by generating solutions in-situ within the sealed membrane structure.
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
This configuration ensures the purity and stability of the generated solutions, enabling their use in high-pressure chromatography systems and allowing for precise control of solution concentration based on applied current, thus overcoming previous limitations in solution purity and pressure resistance.
Implementation Method 1
Under the action of a direct current electric field, H2O between the anion membrane composite layer and the cation membrane composite layer is easily dissociated into H+ and OH-
Implementation Method 2
ion exchange membranes of two different polarities are used to respectively isolate an eluent channel from regeneration liquid channels
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A dual-membrane on-line generator for an acid or alkali solution is provided, including an upper electrolytic cell body (3), a middle electrolytic cell body (4) and a lower electrolytic cell body (5) which are clamped by an upper fastening steel plate (1) and a lower fastening steel plate (2), an upper regeneration liquid channel (A), a middle eluent channel (B) and a lower regeneration liquid channel (C) being provided on the middle electrolytic cell body (4).