Forward Osmosis Membrane Salt Reverse Diffusion
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Solution Overview
Problem
Existing forward osmosis membranes face challenges in achieving both low salt reverse diffusion and high water permeability, often sacrificing one performance for the other, and are not durable enough for repeated use in high-concentration concentration processes, especially when used in modular form.
Innovation Solution
A forward osmosis membrane with a separation active layer on a microporous support membrane, specifically designed to have a polymer layer with a polycondensation product of polyfunctional amines and acid halides, is developed, which maintains low salt reverse diffusion and high water permeability, and is made durable through a heat-treatment process to ensure long-term performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a reverse osmosis membrane is applied to the forward osmosis method, then high water permeability under pressure is achieved, but the membrane is not suitable for forward osmosis and salt reverse diffusion increases
Solution Approach 1:
The patent changes the operational parameters by applying forward osmosis (osmotic pressure difference) instead of reverse osmosis (high pressure) to the membrane system, transforming the driving force mechanism to achieve both high water permeability and low salt reverse diffusion
Solution Approach 2:
The patent uses a composite membrane structure with a microporous support membrane and a separation active layer formed by interfacial polymerization, combining the mechanical strength of the support with the selective separation properties of the active layer to optimize both water permeability and salt rejection
2Speed
If a separation active layer is formed by interfacial polymerization on a hollow fiber membrane, then high water permeability is achieved, but salt reverse diffusion reduction is insufficient
Solution Approach 1:
The patent applies local quality by forming a thin separation active layer with specific polymer composition and structure on the membrane surface through interfacial polymerization, creating a localized region with optimized properties for both water permeability and salt reverse diffusion reduction
Solution Approach 2:
The patent optimizes the polymerization conditions, monomer concentrations, and reaction time parameters to control the thickness and structure of the separation active layer, achieving the balance between water permeability and salt reverse diffusion
3Speed
If a support membrane with high porosity is used, then water permeability is improved, but salt reverse diffusion increases
Solution Approach 1:
The patent creates local quality differentiation by having a highly porous support membrane for water transport while covering it with a dense separation active layer that blocks salt, so each layer performs its specialized function without compromising the other
Solution Approach 2:
The patent combines the microporous support membrane (providing mechanical strength and water permeability) with the separation active layer (providing salt rejection) into a composite structure where the synergistic effect resolves the contradiction between porosity and salt diffusion
4Productivity
If the membrane is used for repeated concentration processes, then productivity is improved, but membrane durability and performance retention are insufficient
Solution Approach 1:
The patent performs preliminary action by conducting heat treatment and optimization of the separation active layer structure before the membrane is put into repeated use, pre-conditioning the membrane to enhance its durability and performance retention for long-term productivity
Solution Approach 2:
The composite structure with the robust microporous support and the optimized separation active layer provides both the performance needed for high productivity and the structural integrity needed for durability during repeated concentration processes
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 extremely low salt reverse diffusion and maintains high water permeability, allowing for efficient concentration of solutions without significant diffusion of the draw solution, even after multiple uses, and retains performance over repeated concentration cycles.
Implementation Method 1
a separation active layer of a polymer is provided on a surface of a microporous support membrane
Implementation Method 2
The forward osmosis method is a method of transferring a solvent from a raw material liquid to a draw solution by adjoining a raw material liquid and a draw solution having a higher osmotic pressure than the raw material liquid via a forward osmosis membrane. The driving force of the forward osmosis method is the osmotic pressure difference between the raw material liquid and the draw solution.
Implementation Method 3
is made durable through a heat-treatment process to ensure long-term performance
Data Source
AI summary
Provided are a forward osmosis membrane, a forward osmosis membrane module, and a manufacturing method thereof, wherein a forward osmosis membrane, which achieves an extremely favorable reduction in the reverse diffusion of salt compared to the prior art and has a predetermined water permeability, is developed thereby bringing about: practicality in that a liquid-like raw material solution used in actual concentration operations can be concentrated with suppressed diffusion of an induction solution even when used multiple times; and durability in that the performance of the membrane can be maintained within a predetermined range even when a raw material solution having an osmotic pressure is concentrated multiple times.