Separation Membrane with Graded Pore Structure
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Solution Overview
Problem
Existing separation membranes, such as those produced by interfacial polymerization and non-solvent phase separation methods, achieve adequate permeation and separation performance but fail to prevent defects effectively.
Innovation Solution
A separation membrane with specific structural characteristics, including regions of varying pore diameters and open pore ratios, is developed, comprising a layer with thicknesses of 0.5 μm to 100 μm, average pore diameters of 0.3 nm to 3.0 nm, and open pore ratios that satisfy specific ratios, and optionally includes a porous support membrane for enhanced strength and permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interfacial polymerization or non-solvent phase separation methods are used, then permeation performance and separation performance can be obtained, but defect occurrence cannot be sufficiently prevented
Solution Approach 1:
The patent applies local quality by creating distinct regions within the membrane layer with different pore diameters and open pore ratios. Specifically, it defines region a (50-150 nm from surface A), region b (50-150 nm from surface B), and region c (central 100 nm thickness), each with controlled pore characteristics. This regional differentiation allows simultaneous optimization of defect prevention, permeation, and separation performance in different locations of the membrane.
2Productivity
If membrane thickness is reduced to improve permeation performance, then water permeation flux increases, but mechanical strength and defect resistance decrease
Solution Approach 1:
The patent employs composite material principles by combining a thin active separation layer (0.5-100 μm) with a porous support membrane (5-500 μm thickness). This composite structure allows the thin layer to provide high permeation performance while the support membrane contributes mechanical strength and defect resistance, achieving both high water permeation flux and adequate mechanical properties.
3Reliability
If pore diameter is reduced to improve separation performance, then salt rejection ratio increases, but water permeation flux decreases
Solution Approach 1:
The patent resolves the separation-permeation trade-off by implementing local quality with different pore characteristics in different regions. Region a and region b near the surfaces have pore diameters of 0.3-3.0 nm for effective separation, while region c in the center has controlled pore structure to maintain permeation pathways. The open pore ratios are also differentiated (Ha and Hb: 2-80%, Hc: 40% or less), allowing simultaneous achievement of high salt rejection and adequate water flux.
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 excellent permeation and separation performance while minimizing defects, suitable for various applications including water treatment, medical, and gas separation, with improved water permeation flux and salt rejection ratios.
Implementation Method 1
a layer (I) having a thickness of 0.5 μm to 100 μm, in which, when, in a cross section of the layer (I) in a thickness direction, a region at a depth of 50 nm to 150 nm from a surface (surface A) is defined as a region a, a region at a depth of 50 nm to 150 nm from the other surface (surface B) is defined as a region b, and a region having a thickness of 100 nm which is at the same depth from both of the surfaces is defined as a region c, both of an average pore diameter Pa of the region a and an average pore diameter Pb of the region b are 0.3 nm to 3.0 nm
Implementation Method 2
a water treatment membrane called reverse osmosis membrane can remove ions, it is considered promising as means of producing pure water from seawater or brackish water
Data Source
AI summary
The problem addressed by the present invention is to provide a separation membrane with superior permeation performance and separation performance and having few occurrences of defects. The present invention relates to a separation membrane wherein: the separation membrane has a layer (I) with a thickness of 0.5-100 μm; letting, in a cross-section in the direction of thickness of the layer (I), region a be a region with a depth of 50-150 nm from a surface (surface A), region b a region with a depth of 50-150 nm from the other surface (surface B), and region c a region with a thickness of 100 nm where the depth from both surfaces is the same, the average pore diameter Pa for region a and the average pore diameter Pb for region b are both 0.3-3.0 nm and the average pore diameter Pc for region c is 3.0 nm or less; and the percentage of open area Ha for region a, the percentage of open area Hb for region b, and the percentage of open area Hc for region c satisfy the following equations. 2Hc<Ha 2Hc<Hb