Gradient Hollow Fiber Membrane for Permeation-Fractionation Trade-off
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Solution Overview
Problem
Hollow fiber membranes face a trade-off between permeation performance and fractionation characteristic, making it difficult to enhance both simultaneously, and existing production methods using fluorine-based materials often result in reduced strength and uneven thickness, leading to issues like peeling-off and increased production costs.
Innovation Solution
A porous hollow fiber membrane with a gradient structure containing a vinylidene fluoride-based resin and a crosslinked polyvinylpyrrolidone-based resin, where the pore diameter decreases towards the inner or outer peripheral surface, enhancing both permeation performance and fractionation characteristic while maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If permeation performance is enhanced, then a smaller membrane area is needed and device miniaturization is achieved, but fractionation characteristic is reduced
Solution Approach 1:
The invention applies local quality by creating a gradient pore structure where the pore diameter varies through the membrane thickness. The outer peripheral surface has smaller pores (0.01-0.5 μm) for high fractionation, while the inner peripheral surface has larger pores (0.5-5 μm) for high permeation. This spatial variation in pore size allows different regions to perform different functions simultaneously, resolving the trade-off between permeation performance and fractionation characteristic.
Solution Approach 2:
The membrane is segmented into distinct functional zones: a filter area with small pores for fractionation, a support area with large pores for structural support and permeation, and a backwash area for maintenance. This segmentation allows each zone to optimize its specific function without compromising the overall performance of the membrane system.
2Manufacturing precision
If fractionation characteristic is enhanced, then better separation of targets is achieved, but permeation performance is reduced
Solution Approach 1:
The gradient pore structure concentrates the fractionation function in the outer peripheral surface region with smaller pores, while the inner peripheral surface region with larger pores provides high permeation capacity. This local specialization allows the membrane to achieve both high fractionation characteristic and high permeation performance simultaneously.
3Reliability
If a fluorine-based material is used to enhance chemical and physical durability, then resistance is improved, but strength is reduced and peeling-off occurs
Solution Approach 1:
The invention uses a composite material system combining vinylidene fluoride-based resin (providing chemical durability) with polyvinylpyrrolidone-based resin (providing mechanical strength and hydrophilicity). The crosslinked polyvinylpyrrolidone forms a three-dimensional network structure that reinforces the membrane, preventing peeling-off while maintaining the chemical resistance of the fluorine-based material.
Solution Approach 2:
The invention changes the physical and chemical parameters of the membrane by introducing crosslinked polyvinylpyrrolidone, which modifies the mechanical properties (increasing strength), surface properties (enhancing hydrophilicity), and structural integrity (preventing peeling). This parameter change allows the membrane to maintain chemical durability while gaining mechanical strength.
4Reliability
If a fluorine-based material is used to enhance chemical and physical durability, then resistance is improved, but uneven thickness is caused and production costs increase
Solution Approach 1:
The composite material system with crosslinked polyvinylpyrrolidone provides a more forgiving matrix that allows for better thickness control during manufacturing. The crosslinked network structure compensates for thickness variations, maintaining performance consistency across the membrane surface while reducing production costs associated with precision manufacturing requirements.
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 achieves improved permeation performance, fractionation characteristic, and contamination resistance with enhanced hydrophilicity, reducing the risk of peeling-off and lowering production costs by forming a dense layer for fractionation and a porous layer for support, resulting in a more efficient and cost-effective separation technology.
Implementation Method 1
hydrophilized by containing a crosslinked body of a polyvinylpyrrolidone-based resin
Implementation Method 2
having a gradient structure in which a pore diameter of pores in the hollow fiber membrane gradually becomes smaller at least toward one of inner and outer peripheral surface sides
Data Source
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AI summary
One aspect of the present invention concerns a porous hollow fiber membrane containing a vinylidene fluoride-based resin. The hollow fiber membrane has a gradient structure in which a pore diameter of pores in the hollow fiber membrane gradually becomes smaller at least toward one of inner and outer peripheral surface sides and is hydrophilized by containing a crosslinked body of a polyvinylpyrrolidone-based resin.