Forward Osmosis Membrane Module with Dense Interface Layer
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Solution Overview
Problem
Forward osmosis membrane modules face challenges with pressure resistance and durability, particularly under positive pressure, leading to potential detachment of the separation function layer from the porous support membrane, which affects performance and longevity.
Innovation Solution
A forward osmosis membrane module is designed with a hollow fiber support membrane having a dense layer with a void percentage of 40% or lower up to 1.0 μm from the interface with the separation function layer, and a separation function layer with an average thickness of 2.0 μm or lower and a coefficient of variation of 30% or lower, along with a method involving a separation function layer-forming step, liquid-encapsulating step, and heat treatment to enhance adhesiveness and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the separation function layer is made thinner to improve permeability, then the permeation volume increases, but the layer becomes more susceptible to detachment under pressure
Solution Approach 1:
The patent applies local quality by creating a dense layer with specific void percentage (40% or lower) at the interface between the porous support and separation function layer. This localized structural modification provides enhanced mechanical interlocking and adhesion at the critical interface region, allowing the separation function layer to maintain both thinness for high permeability and sufficient bonding strength to resist detachment under operating pressures.
2Productivity
If the void percentage in the porous support is increased to improve permeability, then the permeation volume increases, but the structural integrity and pressure resistance decrease
Solution Approach 1:
The patent implements local quality by specifying that the dense layer at the interface region must have a void percentage of 40% or lower, while other regions of the porous support can maintain higher void percentages for permeability. This localized control of porosity allows the membrane to achieve both high overall permeation volume and sufficient structural integrity at the critical interface to withstand system pressures.
Solution Approach 2:
The patent employs composite materials by combining a porous support membrane with a separation function layer to form a composite hollow fiber membrane structure. The porous support provides mechanical strength and permeability, while the separation function layer provides the separation function. This composite structure allows each component to contribute its advantageous properties, achieving both high permeation volume and pressure resistance.
3Productivity
If the separation function layer thickness is reduced to improve permeability, then the permeation volume increases, but the manufacturing precision requirements become more stringent
Solution Approach 1:
The patent applies parameter changes by establishing specific numerical criteria for the dense layer void percentage (40% or lower) and separation function layer thickness (2.0 μm or lower with 30% or lower coefficient of variation). By defining these precise parameter ranges, the patent provides clear manufacturing guidelines that balance the need for thin separation layers for high permeability with controllable manufacturing precision 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 solution provides a forward osmosis membrane module with excellent physical durability and stable high performance, capable of withstanding system pressures and maintaining effective separation performance.
Implementation Method 1
the hollow fiber support membrane has a dense layer with a void percentage of 40% or lower at a location up to 1.0 μm in a depthwise direction from an interface between the porous support and the separation function layer
Implementation Method 2
Forward osmosis is known as a method for concentrating feed solutions. In a forward osmosis method, a feed solution and a draw solution having a higher osmotic pressure than the feed solution are brought adjacent to each other across a forward osmosis membrane, causing the solvent to move from the feed solution to the draw solution.
Implementation Method 3
Membranes suited for forward osmosis methods are designed to have high permeation volume (permeability) for solvents from the feed solution into the draw solution
Implementation Method 4
a method involving a separation function layer-forming step, liquid-encapsulating step, and heat treatment to enhance adhesiveness and durability
Data Source
AI summary
Provided is a forward osmosis membrane module composed of a plurality of hollow-fiber forward osmosis membranes. The forward osmosis membranes are each provided with a separation function layer on a surface of a hollow-fiber support membrane having a porous support body. The membrane surface area of the forward osmosis membrane module is 0.1 m2 or more. The porous support body is such that the porosity of a dense layer up to 1.0 μm from the interface with the separation function layer is 40% or less. The average thickness of the separation function layer is 2.0 μm or less, and the variation coefficient of the average thickness of the separation function layer is 30% or less in the radial direction and longitudinal direction of the forward osmosis membrane module.