Gradient Ion Exchange Membrane for Monovalent Anion Selectivity
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Solution Overview
Problem
Existing ion-exchange membranes lack sufficient monovalent anion selectivity, failing to effectively distinguish and transmit monovalent anions over polyvalent anions at a high rate, which is crucial for processes like high-purity salt production, caustic soda production, soft water production, fermentation processes, and wastewater neutralization.
Innovation Solution
A monovalent anion selective ion exchange membrane is designed with a porous polymer support impregnated by anion and cation exchange polymer electrolytes, where the central portion is dominated by anion exchange polymer electrolyte and the surface portion by cation exchange polymer electrolyte, maintaining a specific ratio to enhance monovalent anion permeation and reduce polyvalent anion permeation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ion-exchange membrane is used, then ion transmission is achieved, but monovalent anion selectivity is insufficient
Solution Approach 1:
The patent applies local quality by creating distinct regions within the ion-exchange membrane: the surface layer is dominated by cation-exchange polymer electrolyte to repel polyvalent anions, while the inner layer contains anion-exchange polymer electrolyte to selectively transmit monovalent anions. This spatial differentiation of functional properties resolves the contradiction between selectivity and transmission efficiency.
Solution Approach 2:
The patent uses composite materials by combining two types of polymer electrolytes (cation-exchange and anion-exchange) in a layered structure within a porous polymer support. This composite approach enables the membrane to simultaneously achieve monovalent anion selectivity through the anion-exchange layer and polyvalent anion rejection through the cation-exchange layer, resolving the selectivity-transmission contradiction.
2Reliability
If the membrane structure is simplified, then manufacturing is easier, but monovalent anion selectivity decreases
Solution Approach 1:
Rather than creating a complex multi-component system, the patent uses local quality by forming different polymer electrolyte regions at different locations within a single porous polymer support structure. The cation-exchange polymer forms on the surface while the anion-exchange polymer fills the interior pores, achieving high selectivity through this simple yet effective spatial arrangement.
Solution Approach 2:
The patent applies self-service by utilizing the inherent properties of the polymer electrolytes to automatically form the desired layered structure. When both cation-exchange and anion-exchange polymers are introduced to the porous support, they naturally segregate into surface and interior regions based on their electrostatic interactions and concentration gradients, eliminating the need for complex controlled assembly 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 high selectivity for monovalent anions by leveraging the repulsive forces between polyvalent anions and cation exchange polymer electrolyte on the surface, while allowing monovalent anions to permeate efficiently, thus improving the purity and efficiency of related industrial processes.
Implementation Method 1
leveraging the repulsive forces between polyvalent anions and cation exchange polymer electrolyte on the surface
Implementation Method 2
anion exchange polymer electrolyte impregnated in the central portion of the porous polymer support
Data Source
AI summary
Provided are a monovalent anion selective ion exchange membrane and a method of manufacturing the ion exchange membrane. In regard to the monovalent anion selective ion exchange membrane, a surface portion thereof has a high amount ratio of a cation exchange polymer electrolyte, a central portion thereof has a high amount ratio of an anion exchange polymer electrolyte, and an amount ratio of the anion exchange polymer electrolyte with respect to the cation exchange polymer electrolyte continuously increases in the thickness direction thereof from the surface toward the center. Due to this structure, compared to monovalent anions, polyvalent anions may permeate much less through the exchange membrane. Thus, high selectivity for monovalent anions may be obtained.