Composite Hollow Fiber Membrane Module for Forward Osmosis
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Solution Overview
Problem
Existing composite hollow fiber membrane modules face challenges in achieving uniform thickness of the separation active layer, leading to variations in water permeability and reverse salt flux, which affects their performance in applications such as desalination and wastewater treatment.
Innovation Solution
A composite hollow fiber membrane module is developed with a separation active layer of a polymer thin film on the inner surface of microporous hollow fibers, formed through interfacial polymerization using polyfunctional amines and polyfunctional acid halides or isocyanates, ensuring uniform thickness and high water permeability with low reverse salt flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a polymer thin film is formed on the outer surface of hollow fibers by interfacial polymerization using a guide roll, then continuous manufacturing is achieved, but the polymer film is damaged due to contact with the guide roll and contact between hollow fibers
Solution Approach 1:
The invention inverts the conventional approach by forming the polymer thin film on the inner surface of hollow fibers instead of the outer surface. This allows the fibers to be filled with first solution, sealed at both ends, and then contacted with second solution from the outside, enabling continuous manufacturing without guide rolls that cause mechanical damage to the polymer film.
Solution Approach 2:
The invention segments the manufacturing process into distinct stages: filling hollow fibers with first solution, sealing both ends, immersing in second solution for interfacial polymerization, and removing excess solution. This segmentation eliminates the need for continuous guide roll contact while maintaining production efficiency.
2Reliability
If a polymer thin film is formed on the inner surface of hollow fibers by filling first solution and using high-pressure air to remove excess, then the polymer film is protected from damage, but the thickness of the separation active layer becomes uneven
Solution Approach 1:
The invention introduces pressure control as a feedback mechanism during the removal of excess first solution. By controlling the pressure difference between the inside and outside of hollow fibers, the system achieves uniform liquid film thickness before interfacial polymerization, ensuring uniform separation active layer thickness while protecting the polymer film from mechanical damage.
3Ease of manufacture
If high-pressure air is used to remove excess first solution from hollow fibers, then the liquid film thickness varies due to pressure loss, but this method is simple to implement
Solution Approach 1:
The invention replaces the high-pressure air blasting method with a controlled pressure difference system. Instead of using high-velocity gas flow that causes pressure loss and uneven film formation, the system uses regulated pressure differential to uniformly remove excess liquid while maintaining consistent film thickness across all hollow fibers.
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 module achieves stable performance with uniform average thickness of the separation active layer, resulting in high water permeability and low reverse salt flux, making it suitable for desalination, wastewater treatment, and other water treatment applications.
Implementation Method 1
a composite hollow fiber membrane module having selective permeability that is used to separate solvents by removing solids or solutes from a liquid mixture
Implementation Method 2
Interfacial polymerization is a technology consisting of respectively dissolving two types of reactive monomers in water and an organic solvent not miscible with water, and forming a polymer by enabling the monomers to react at the interface of the two solutions
Implementation Method 3
extraction of water from the raw water into the induction solution is driven by an osmotic pressure difference
Data Source
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Figure 3(a)~3(d)
AI summary
The present invention offers a forward osmosis composite hollow fiber membrane module having hollow fiber bundles comprising a plurality of hollow fibers, the hollow fibers having a separation layer composed of a macromolecular polymer thin film provided on the inner surface of a microporous hollow fiber supporting membrane, wherein the membrane area of the hollow fiber bundle is at least 1 m2, and a variation coefficient for the average thickness of the separation layer in the radial direction and the lengthwise direction of the hollow fiber bundles, as calculated by a method of measuring the mass of the separation layer portion in a scanning electron microscope image of a cross section of the separation layer in the thickness direction, is 0% to 60%.