UV-Initiated Ion Exchange Membrane for Low Resistance Desalination
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Solution Overview
Problem
Existing ion exchange membranes for water desalination and electrodialysis face challenges with high resistance, low permselectivity, and high production costs, which hinder efficient seawater desalination and agricultural irrigation water treatment.
Innovation Solution
The method involves producing ion exchange membranes through UV-initiated polymerization of a charged monomer solution on a polymeric microporous substrate, using photopolymerization initiators like 1-hydroxy-cyclohexyl phenyl ketone and bis-acylphosphinoxide, to create cation and anion exchange membranes with low resistance and high permselectivity, suitable for desalination and agricultural applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional thermal polymerization is used to produce ion exchange membranes, then complete polymerization can be achieved, but production time is extended and energy consumption increases
Solution Approach 1:
The patent replaces thermal polymerization with UV photopolymerization, substituting thermal energy with optical energy to initiate and accelerate the polymerization process. This substitution enables complete polymerization to occur in significantly shorter time (seconds to minutes versus hours) while reducing overall energy consumption, as UV light provides concentrated energy only when needed for initiation rather than sustained thermal energy input
Solution Approach 2:
The patent changes the polymerization initiation parameter from thermal activation to UV light activation. By incorporating photopolymerization initiators and exposing the monomer solution to UV radiation, the polymerization process is triggered and completed rapidly at room temperature, dramatically reducing both production time and energy consumption compared to conventional thermal methods
2Reliability
If ion exchange membranes are produced with higher permselectivity, then desalination efficiency improves, but membrane resistance increases
Solution Approach 1:
The patent applies local quality by creating distinct functional zones within the membrane structure. The microporous substrate provides mechanical support and porosity, while the polymerized monomer layer provides ion exchange functionality with controlled permselectivity. This localized functional differentiation allows optimization of each zone's properties independently, achieving high permselectivity without excessive resistance
Solution Approach 2:
The patent creates a composite membrane structure combining a microporous substrate with a polymerized ion exchange monomer layer. This composite structure integrates the mechanical strength and porosity of the substrate with the ion selective properties of the polymer layer, achieving both high permselectivity and acceptable resistance through synergistic material combination
3Ease of manufacture
If traditional polymerization methods are used, then production costs are controlled, but production time and energy consumption increase
Solution Approach 1:
The patent replaces energy-intensive thermal polymerization with UV photopolymerization, substituting sustained thermal energy input with targeted optical energy input. This substitution dramatically reduces production time while the use of photopolymerization initiators and UV equipment maintains manufacturing simplicity, achieving both cost-effectiveness and high productivity
Solution Approach 2:
The patent enables the monomer solution to self-polymerize when exposed to UV light without requiring external heating or complex process control. The photopolymerization initiators embedded in the monomer solution activate the polymerization automatically upon UV exposure, eliminating the need for external energy input and simplifying the manufacturing process while reducing both time and cost
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
This approach results in ion exchange membranes with resistance below 2 Ω-cm2 and permselectivity above 90%, enhancing the efficiency and cost-effectiveness of seawater desalination and agricultural water treatment, while providing mechanical strength and durability.
Implementation Method 1
polymerizing the at least one functional monomer by exposing the saturated polymeric microporous substrate to ultraviolet light in a substantially oxygen free environment at room temperature for an amount of time effective to cross-link the at least one functional monomer
Data Source
AI summary
Methods of producing an ion exchange membrane support are disclosed. The methods include saturating a polymeric microporous substrate with a charged monomer solution comprising at least one functional monomer, a cross-linking agent, and an effective amount of at least one photopolymerization initiator and polymerizing the at least one functional monomer by exposing the saturated polymeric microporous substrate to ultraviolet light under conditions effective to cross-link the at least one functional monomer and produce the ion exchange membrane support. Methods of producing a monovalent selective ion exchange membrane are also disclosed. The methods include functionalizing an exterior surface of the ion exchange membrane support with a charged compound layer, drying the ion exchange membrane support and soaking the ion exchange membrane support in a solution comprising an acid or a base for an amount of time effective to produce the monovalent selective ion exchange membrane.