Ion Exchange Membrane Stack Color Coding Assembly
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Solution Overview
Problem
The existing membrane stacks used in electrodialysis units are challenging to manufacture correctly due to the visual indistinguishability of anion exchange membranes (AEMs) and cation exchange membranes (CEMs), leading to errors in alternating their order, which results in defective units.
Innovation Solution
The membranes are made distinguishable by incorporating dyes that create visibly different color properties between AEMs and CEMs, allowing for easier identification and correct assembly, using a process that includes curable compositions with photoinitiators and specific dye amounts to ensure distinct colors under various lighting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If AEMs and CEMs are made visually indistinguishable, then manufacturing cost is reduced, but manufacturing precision deteriorates due to errors in alternating membrane order
Solution Approach 1:
The patent applies color changes by incorporating dyes into the membrane structures. AEMs are dyed with first dyes (e.g., yellow, orange, red) and CEMs are dyed with second dyes (e.g., green, blue, purple) that are visually distinguishable from the first dyes. This allows operators to easily identify and correctly alternate membrane types during assembly, eliminating ordering errors while maintaining cost-effectiveness through simple dye incorporation.
2Manufacturing precision
If dyes are incorporated into membranes to distinguish AEMs and CEMs, then manufacturing precision is improved, but device complexity increases due to additional dyeing processes
Solution Approach 1:
The patent merges the dyeing function with the membrane manufacturing process itself. The dyes are incorporated into the membrane material during production, so that the membranes are provided with distinguishable colors as an integrated part of their structure. This eliminates the need for separate post-manufacturing dyeing steps or complex assembly-time identification systems, thereby improving precision without significantly increasing overall process complexity.
3Ease of operation
If visible color differences are used to identify membrane types, then ease of operation is improved, but loss of substance increases due to dye leaching into processing streams
Solution Approach 1:
The patent employs dyes that are incorporated into the membrane structure and provide sufficient color differentiation for identification purposes during assembly and operation. The dyes are selected and applied in concentrations that ensure visible distinction between AEMs and CEMs while minimizing leaching risks. This approach accepts the temporary presence of dyes during the operational lifecycle of the membranes, balancing identification needs against potential substance loss.
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 solution reduces the likelihood of consecutive membranes of the same charge and facilitates the assembly of correctly ordered membrane stacks, enhancing the manufacturing efficiency and reducing defects in electrodialysis units.
Implementation Method 1
The curable compositions are irradiated with light to cure the compositions to form solid membranes
Implementation Method 2
the colour properties of the AEMs are visibly different to the colour properties of the CEMs
Data Source
AI summary
A stack of ion exchange membranes suitable for water purification comprising a plurality of anion exchange membranes (AEMs) and a plurality of cation exchange membranes (CEMs), wherein the colour properties of the AEMs are visibly different to the colour properties of the CEMs. The invention also provides a process for making membrane stacks in which the likelihood of there being two consecutive membranes of like charge is reduced. Furthermore, it is easy to identify whether there are two consecutive membranes of like charge present in the stacks.