Sulfonated PEEK Membrane Cross-Linking for Dairy Water Recovery
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Solution Overview
Problem
Sulfonated poly(ether ether ketone) membranes face issues with excessive swelling and dimensional instability when wetted, which affects their performance in applications like water recovery from dairy feed streams, and existing cross-linking methods either reduce sulfonation levels or involve direct participation of sulfonic acid groups, limiting their hydrophilicity and durability.
Innovation Solution
A cross-linked sulfonated poly(ether ether ketone) membrane is developed with a C2-6-dicarboxylic cross-linking agent using a Friedel-Crafts type catalyst in a non-aqueous reactive solvent, maintaining high hydrophilicity and sulfonation levels, and combined with a sulfonated microporous poly(ethylene) support layer to form an asymmetric composite membrane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sulfonated poly(ether ether ketone) membranes are used to improve hydrophilicity and water recovery efficiency, then water flux is improved, but dimensional stability and resistance to swelling deteriorate
Solution Approach 1:
The patent employs a composite membrane structure consisting of a sulfonated poly(ether ether ketone) rejection layer combined with a microporous poly(ethylene) support layer. This composite structure allows the sulfonated polymer to provide high hydrophilicity and water flux while the poly(ethylene) support layer provides dimensional stability and resistance to swelling, thus resolving the contradiction between improved water recovery efficiency and deteriorated dimensional stability
Solution Approach 2:
The patent utilizes a microporous poly(ethylene) support layer with controlled porosity to provide mechanical strength and dimensional stability. The porous structure allows water permeation while preventing excessive swelling of the sulfonated polymer layer, thereby maintaining both high water flux and dimensional stability simultaneously
2Stability of the object's composition
If cross-linking is performed using existing methods to improve dimensional stability, then resistance to swelling is improved, but sulfonation levels decrease limiting hydrophilicity
Solution Approach 1:
The patent segments the cross-linking function from the sulfonation function by using two different polymer layers: the sulfonated poly(ether ether ketone) layer maintains high sulfonation levels and hydrophilicity, while the microporous poly(ethylene) support layer provides cross-linked structure for dimensional stability. This segmentation allows both high hydrophilicity and resistance to swelling to be achieved without compromising either property
Solution Approach 2:
The microporous poly(ethylene) support layer acts as an intermediary that provides mechanical strength and dimensional stability to the sulfonated polymer rejection layer. This intermediary structure allows the sulfonated layer to maintain its hydrophilic properties and high sulfonation levels while the support layer prevents excessive swelling, thus resolving the contradiction between resistance to swelling and hydrophilicity
3Reliability
If cross-linking is performed to improve durability and resistance to chemical decomposition, then membrane lifespan is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary sulfonation to the poly(ether ether ketone) polymer before membrane fabrication, creating a sulfonated polymer that inherently provides both hydrophilicity and cross-linking sites. This preliminary chemical modification simplifies the overall manufacturing process by eliminating the need for separate cross-linking steps, thereby improving durability while minimizing manufacturing complexity
Solution Approach 2:
The patent optimizes the degree of sulfonation and the molecular weight of the poly(ether ether ketone) polymer to achieve the desired balance between durability and manufacturing simplicity. By carefully controlling these parameters, the membrane achieves high durability through inherent cross-linking potential while maintaining a relatively simple two-layer fabrication process
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 membrane exhibits improved durability, resistance to chemical decomposition, and efficient water recovery with high rejection of solutes, maintaining performance under hydrostatic or osmotic pressure conditions, suitable for dairy processing operations.
Implementation Method 1
incubating in the presence of a Friedel-Crafts type catalyst a mixture of a chlorosulfonated poly(ether ether ketone) and a C2-6-dioic cross-linking agent
Implementation Method 2
the use of such membranes for the recovery of water from feed streams such as dairy feed streams
Implementation Method 3
maintaining performance under hydrostatic or osmotic pressure conditions
Data Source
AI summary
Durable asymmetric composite membranes consisting of a film of cross-linked sulfonated poly(ether ether ketone) adhered to a sheet of sulfonated microporous poly(ethylene) are disclosed. The membranes have application in the recovery of water from feed streams were the ability to clean in situ is desirable, for example in dairy processing. Methods of preparing cross-linked sulfonated poly(ether ether ketone) suitable for use as a rejection layer in such membranes are also disclosed.