Curable Membranes for Reverse Electrodialysis Power Output

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Solution Overview

Problem

Current membranes used in reverse electrodialysis (RED) systems exhibit high electrical resistance to multivalent ions, particularly magnesium, which reduces the power output and permselectivity, limiting the efficiency of electricity generation from ionic solutions of different salt concentrations.

Innovation Solution

A curable composition comprising non-ionic crosslinkers, curable ionic compounds with anionic groups and ethylenically unsaturated groups, solvents, photoinitiators, and structure modifiers is used to create membranes with low electrical resistance, optimized for multivalent ions by controlling the molar ratios and pH, resulting in improved permselectivity and reduced swelling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ion exchange membranes are used in RED systems, then the membranes provide basic ion exchange functionality, but they exhibit high electrical resistance to multivalent ions (especially magnesium), which reduces power output and permselectivity

Engineering Contradiction:

Improvemembrane performanceVSAvoidpower output

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent changes the chemical parameters of the membrane by incorporating specific ionic compounds (sulfonated polyether ether ketone, carboxymethyl cellulose) and controlling the molar ratio of structure modifiers to ionic compounds (0.25-0.65), thereby reducing electrical resistance to multivalent ions and improving power output

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite membrane material combining multiple components: curable ionic compounds, structure modifiers (divalent/trivalent metal salts), non-ionic crosslinkers, and photoinitiators. This composite structure achieves both low electrical resistance to multivalent ions and high permselectivity, resolving the contradiction between reliability and power output

Inventive Principle:

Principle #40Composite materials

2Power

If the membrane structure is optimized for low electrical resistance, then power output improves, but permselectivity may be compromised

Engineering Contradiction:

Improvepower outputVSAvoidpermselectivity

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent optimizes multiple parameters simultaneously: pH (0.1-6, preferably 0.5-4), molar ratio of structure modifier to ionic compound (0.25-0.65), and crosslinker content (5-50 wt%). These parameter changes achieve both low electrical resistance (high power output) and high permselectivity by controlling the membrane's physical and chemical properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates different functional zones within the membrane by using structure modifiers that locally cluster ionic groups. This local clustering provides low electrical resistance in ion conduction pathways while maintaining overall permselectivity, resolving the contradiction between power output and reliability

Inventive Principle:

Principle #3Local quality

3Power

If the membrane is made more permeable to multivalent ions, then electrical resistance decreases, but the membrane may swell excessively, affecting structural stability

Engineering Contradiction:

Improveelectrical conductivityVSAvoidmembrane swelling

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The patent controls the pH of the curable composition (0.1-6, preferably 0.5-4) and the molar ratio of structure modifiers to ionic compounds (0.25-0.65) to optimize the balance between ion permeability and structural stability. This prevents excessive swelling while achieving low electrical resistance to multivalent ions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary crosslinking of the membrane structure using non-ionic crosslinkers (5-50 wt%) before the membrane is fully hydrated and subjected to ion transport. This pre-crosslinking stabilizes the membrane structure, preventing excessive swelling when the membrane is later exposed to multivalent ions, while still allowing sufficient ion permeability for low electrical resistance

Inventive Principle:

Principle #10Preliminary action

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 membranes demonstrate significantly lower electrical resistance for both multivalent and monovalent ions, enhancing the power output and permselectivity, thereby increasing the efficiency of RED devices in generating electricity from ionic solutions.

Implementation Method 1

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

curable ionic compound(s) comprising an anionic group and at least one ethylenically unsaturated group

Methodology Applied

Scientific EffectIon exchange: Ion Exchange

Data Source

PatentUS10046279B2Curable compositions and membranes

Publication Date: 2018.08.14 FUJIFILM MANUFACTURING EUROPE BV

AI summary

A curable composition comprising the components (i) 0 to 60 wt % non-ionic crosslinker(s); (ii) 20 to 85 wt % curable ionic compound(s) comprising an anionic group and at least one ethylenically unsaturated group; (iii) 15 to 45 wt % solvent(s); (iv) 0 to 10 wt % of photoinitiator(s); and (v) 2 to 45 wt % of structure modifier(s); wherein the molar ratio of component (v): (ii) is 0.25 to 0.65. The compositions are useful for preparing membranes for (reverse) electrodialysis.