Ionic Liquid Supported Membrane for CO2 Removal
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Solution Overview
Problem
Current CO2 control systems for extra-vehicular activity (EVA) are limited by the sorbent's capacity, requiring increased size and weight to extend mission duration, and existing technologies are complex, power-intensive, and unreliable, with challenges in achieving high CO2/O2 selectivity and permeability in polymeric membranes.
Innovation Solution
A supported liquid membrane (SLM) using ionic liquids with amine functional groups is employed, where CO2 forms a metastable complex on the crew side, diffusing through the membrane to decompose at the vacuum side, allowing continuous CO2 removal and regeneration without temperature changes, leveraging the low vapor pressure and high affinity of ionic liquids for CO2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the sorbent capacity is increased to extend mission duration, then the EVA duration is extended, but the size and weight of the life support system increase
Solution Approach 1:
The patent changes the chemical parameters of the sorbent material by using ionic liquids with specific functional groups (carboxylic acid, phenolic hydroxyl, or amine groups) that have high affinity for CO2. This chemical parameter change enables the sorbent to achieve higher capacity and longer duration without proportionally increasing system weight, as the ionic liquids can be applied in thin films on porous substrates.
Solution Approach 2:
The patent employs composite material structure by combining ionic liquids with porous solid substrates (such as porous polymers, metals, or ceramics). This composite approach allows the liquid sorbent to be supported on a lightweight rigid structure, extending mission duration through high CO2 capacity while minimizing the weight penalty compared to using bulk liquid or solid sorbents alone.
2Reliability
If polymeric membranes are used for CO2 separation, then CO2 removal is achieved, but the CO2/O2 selectivity and permeability are insufficient
Solution Approach 1:
The patent transitions from polymeric membrane-based CO2 removal to a liquid-based sorbent system using ionic liquids. This hydraulic approach uses the high solubility and affinity of ionic liquids for CO2 to achieve superior separation performance. The liquid sorbent can be applied as a thin film on porous supports, providing high CO2 capacity and selectivity without the performance limitations of polymeric membranes.
Solution Approach 2:
The patent changes the material phase parameter from solid polymeric membranes to liquid ionic liquids. This parameter change enables dramatically improved CO2/O2 selectivity and permeability because ionic liquids can be tuned through their chemical structure (different functional groups and cations) to optimize CO2 interaction, achieving reliability in CO2 removal that exceeds polymeric membrane capabilities.
3Duration of action of stationary object
If the Metox sorbent system is used for CO2 control, then CO2 removal is achieved, but the system requires increased size and weight to extend mission duration
Solution Approach 1:
The patent adopts a disposable sorbent canister design using ionic liquids impregnated on porous substrates. These canisters are designed for single-use during EVA missions, eliminating the need for complex regeneration systems. The canisters provide extended mission duration through high CO2 capacity and are discarded after use, simplifying the overall system architecture and reducing weight compared to regenerable systems with heating, pumping, and control hardware.
Solution Approach 2:
The patent uses porous solid substrates (porous polymers, metals, or ceramics) as the support structure for the ionic liquid sorbent. The porous structure provides high surface area and volume for CO2 absorption while maintaining low density and lightweight construction. This enables the sorbent canister to achieve extended lifetime and high CO2 capacity without increasing canister weight, as the porous matrix allows efficient CO2 access throughout the sorbent volume.
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 SLM system achieves high CO2 permeance and selectivity, extending mission duration without increasing system size or weight, while maintaining low power demand and high reliability, effectively controlling CO2 levels in space suits.
Implementation Method 1
CO2 forms a metastable complex on the crew side, diffusing through the membrane to decompose at the vacuum side
Implementation Method 2
diffusing through the membrane to decompose at the vacuum side
Implementation Method 3
decompose at the vacuum side
Implementation Method 4
high CO2 permeance and selectivity
Data Source
AI summary
There is disclosed a portable life support system with a component for removal of at least one selected gas. In an embodiment, the system includes a supported liquid membrane having a first side and a second side in opposition to one another, the first side configured for disposition toward an astronaut and the second side configured for disposition toward a vacuum atmosphere. The system further includes an ionic liquid disposed between the first side and the second side of the supported liquid membrane, the ionic liquid configured for removal of at least one selected gas from a region housing the astronaut adjacent the first side of the supported liquid membrane to the vacuum atmosphere adjacent the second side of the supported liquid membrane. Other embodiments are also disclosed.