Monolithic Bipolar Membrane Low Transmembrane Voltage
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Solution Overview
Problem
Existing bipolar membranes have high transmembrane voltages, leading to high energy consumption and increased risk of membrane failure such as burning.
Innovation Solution
A monolithic bipolar membrane with a low transmembrane voltage is developed through a specific preparation method involving prepolymerization, chloromethylation, amination, sulfonation, quaternization, and treatment with FeCl2 and alkaline solutions to optimize the membrane structure and reduce hydrolysis voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional bipolar membrane is used, then the membrane structure is simple and easy to manufacture, but the transmembrane voltage is high leading to high energy consumption and membrane burning risk
Solution Approach 1:
The patent introduces a three-layer structure with distinct functional regions: a cation-exchange layer containing quaternary ammonium groups, an anion-exchange layer containing sulfonic acid groups, and an interfacial layer with tertiary amine groups that catalyze water dissociation. This local differentiation of chemical properties and functions across the membrane structure enables reduced transmembrane voltage while maintaining stability.
Solution Approach 2:
The bipolar membrane is constructed as a composite material system combining polyolefin base material with grafted functional groups (quaternary ammonium, sulfonic acid, and tertiary amine). This composite structure integrates the mechanical strength of polyolefin with the electrochemical functionality of ion-exchange groups, achieving both low energy consumption and high reliability.
2Use of energy by moving object
If the transmembrane voltage is reduced to save energy, then energy consumption decreases, but the membrane performance and stability may be compromised
Solution Approach 1:
The patent systematically optimizes multiple parameters including the density of ion-exchange groups, the thickness ratios of different layers, the specific chemical structure of functional groups, and the grafting degrees. By precisely controlling these parameters during the multi-step synthesis process, the membrane achieves optimal performance with transmembrane voltage reduced to 1.15V while maintaining stable operation.
3Use of energy by moving object
If a complex multi-step preparation method is used to reduce transmembrane voltage, then the energy consumption is reduced, but the manufacturing complexity increases
Solution Approach 1:
The preparation process is divided into distinct sequential stages: (1) chloromethylation of the polyolefin membrane, (2) amination to introduce tertiary amine groups, (3) sulfonation to create the anion-exchange layer, and (4) quaternization to form the cation-exchange layer. Each stage is independently optimized and controlled, making the complex overall process manageable and reproducible.
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 monolithic bipolar membrane effectively reduces the transmembrane voltage to as low as 1.15 V, achieving stable operation and significantly reducing energy consumption.
Implementation Method 1
heating the membrane liquid to be under a liquid state, at which time infiltrating and impregnating a polyolefin thin membrane in the membrane liquid
Implementation Method 2
putting the impregnated thin membrane into water at a second temperature for a polymerization reaction, so as to prepare a basement membrane after the polymerization reaction is completed
Implementation Method 3
soaking the bipolar membrane treated in the step (6) in a FeCl2 solution additionally, and after soaking for a certain time, taking out the membrane, soaking and transforming the membrane in an alkaline solution
Data Source
AI summary
The present invention relates to a monolithic bipolar membrane with a low transmembrane voltage and a preparation method thereof. The preparation method includes the following steps: preparing a membrane liquid with styrene and divinylbenzene; heating the membrane liquid, and then impregnating a polyolefin thin membrane; polymerizing an impregnated thin membrane and preparing a basement membrane; producing the basement membrane into a semi-anion membrane; additionally partially sulfonating and additionally quaternizing one side of the semi-anion membrane; then, soaking the bipolar membrane in a FeCl2 solution, transforming the bipolar membrane in an alkaline solution, and preparing the bipolar membrane. The present invention effectively reduces the transmembrane voltage, thereby being beneficial to reducing energy consumption.