Capacitive Deionization Spacer Structure for Ion Conductivity
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Solution Overview
Problem
Existing capacitive deionization technologies face inefficiencies in removing ions from hard water, particularly in regions with high mineral content, leading to energy inefficiencies and lime scale formation, and require improvements for seawater desalination and soft water production in an environmentally friendly manner.
Innovation Solution
A capacitive deionization apparatus featuring porous electrodes and a spacer structure made from a copolymer of a polyurethane backbone with carboxyl or sulfonic acid groups and an ion conductive monomer, which forms cross-linking bonds with a second polymer, enhancing ion conductivity and preventing electrical short circuits, thereby improving deionization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional spacer structure is used in CDI apparatus, then the device complexity is reduced and ease of manufacture is improved, but the ion conductivity is insufficient and deionization efficiency deteriorates
Solution Approach 1:
The spacer structure is constructed as a composite material comprising a polyurethane backbone containing carboxyl or sulfonic acid groups, cross-linked with a second polymer through functional groups. This composite structure provides both mechanical strength and enhanced ion conductivity, resolving the contradiction between deionization efficiency and structural simplicity.
Solution Approach 2:
The spacer structure incorporates ion conductive monomers with carboxyl groups that can be cross-linked with the polyurethane backbone. By changing the chemical parameters of the spacer material (adding ion conductive groups and cross-linking), the ion conductivity is significantly improved while maintaining structural integrity, thus enhancing deionization efficiency without excessive complexity.
2Reliability
If the spacer structure uses highly ion conductive materials, then deionization efficiency is improved, but mechanical strength may be compromised
Solution Approach 1:
The spacer structure exhibits local quality differentiation: the polyurethane backbone provides mechanical strength and structural framework, while the incorporated ion conductive monomers with carboxyl groups provide localized ion conductivity pathways. The cross-linking with second polymer reinforces the structure in regions where ion conductive groups are present, achieving both high ion conductivity and mechanical strength simultaneously.
Solution Approach 2:
The composite nature of the spacer combines the mechanical properties of polyurethane with the ion conductive properties of cross-linked polymer networks containing carboxyl or sulfonic acid groups. This composite structure allows the spacer to fulfill dual functions: maintaining structural integrity and providing efficient ion transport pathways, thereby resolving the contradiction between mechanical strength and deionization efficiency.
3Reliability
If conventional electrodes are used without advanced spacer structures, then energy consumption is lower, but ion removal efficiency deteriorates
Solution Approach 1:
The advanced spacer structure acts as an intermediary between the electrodes and the fluid, providing ion conductive pathways that facilitate ion transport to the electrode surfaces. The carboxyl and sulfonic acid groups in the spacer create localized ion concentration zones, enhancing the efficiency of ion removal without requiring increased energy input, thus resolving the contradiction between ion removal efficiency and energy consumption.
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 apparatus achieves higher ion removal efficiency and purity, reduces energy consumption, and maintains mechanical strength, allowing for effective treatment of fluids with low ion concentrations, including seawater, while preventing electrode short circuits and maintaining long-term stability.
Implementation Method 1
a copolymer prepared by copolymerizing a mixture of a polyurethane backbone including a carboxyl group or a sulfonic acid group and an ion conductive monomer including a carboxyl group and a cation exchange group
Implementation Method 2
a second polymer including a functional group that reacts with the carboxyl group or sulfonic acid group and forms a cross-linking bond with the polyurethane backbone
Implementation Method 3
apply a voltage to porous electrodes having nano-sized pores to make them carry a polarity and thereby adsorb ionic materials from a medium such as hard water onto the surface of the electrodes
Data Source
AI summary
The present disclosure relates to a spacer structure that is configured to be disposed between a pair of electrodes in a capacitive deionization apparatus so as to provide a space for flowing a fluid therethrough. The spacer structure includes a copolymer prepared by copolymerizing a mixture of a polyurethane backbone including a carboxyl group or a sulfonic acid group, an ion conductive monomer including a carboxyl group and a cation exchange group, and a second polymer including a functional group that reacts with the carboxyl group or sulfonic acid group and forms a cross-linking bond with the polyurethane backbone.