Composite Membrane Pervaporation Using Pore-Filling Polymer
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Solution Overview
Problem
Traditional composite membranes face challenges in achieving effective pervaporation performance while maintaining mechanical strength, as they tend to swell when exposed to mixed solvents, leading to reduced selectivity and flux.
Innovation Solution
The development of asymmetric composite membranes with a porous substrate and a pore-filling polymer, where the polymer is more permeable to one liquid over another, and optionally incorporating ionic liquids or amorphous fluorochemical films for enhanced durability and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional composite membranes are used to achieve pervaporation performance, then selectivity and flux are improved, but mechanical strength deteriorates due to swelling when exposed to mixed solvents
Solution Approach 1:
The invention uses a composite membrane structure consisting of a porous support substrate combined with a pore-filling polymer layer. The porous substrate provides mechanical strength and structural stability, while the pore-filling polymer provides selective pervaporation performance. This composite structure resolves the contradiction by combining materials with complementary properties - the rigid substrate prevents swelling-induced mechanical failure while the polymer layer enables selective separation.
Solution Approach 2:
The invention employs a porous support substrate with controlled pore structure to accommodate the pore-filling polymer. The porous structure allows the polymer to be distributed throughout the membrane thickness, providing both mechanical integrity through the substrate framework and separation functionality through the polymer-filled pores. This approach maintains mechanical strength while enabling effective pervaporation.
2Manufacturing precision
If pore-filling polymer is used to improve selectivity for alcohol separation, then selectivity is improved, but mechanical durability worsens due to polymer swelling in mixed solvents
Solution Approach 1:
The invention creates a heterogeneous structure where the pore-filling polymer is localized within the pores of the porous substrate rather than forming a continuous dense layer. This local distribution allows the polymer to provide selective separation where needed while the surrounding porous substrate structure prevents overall membrane swelling and maintains mechanical durability. Different regions of the membrane have different functions - the polymer-filled pores provide selectivity while the substrate provides structural stability.
3Productivity
If asymmetric composite membrane structure is used with higher polymer content at one surface, then pervaporation flux is improved, but manufacturing complexity increases
Solution Approach 1:
The invention employs an asymmetric membrane structure where the pore-filling polymer is non-uniformly distributed with higher concentration at one surface (the feed side) and lower concentration at the other surface (the permeate side). This asymmetric distribution optimizes flux by creating a concentration gradient that enhances mass transfer driving force. The manufacturing complexity is managed by using infiltration or deposition processes that naturally create asymmetric distributions, such as directional infiltration from one side or surface-selective polymerization.
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
These membranes demonstrate improved selectivity and flux for separating alcohol from gasoline mixtures, maintaining mechanical strength and durability, making them suitable for applications like flex-fuel engines.
Implementation Method 1
selectively pervaporating alcohol from an alcohol and gasoline mixture
Implementation Method 2
the pore-filling polymer is more permeable to alcohol than gasoline
Implementation Method 3
an ionic liquid (i.e., a liquid ionic compound) mixed with the pore-filling polymer
Implementation Method 4
an amorphous fluorochemical film disposed on the composite membrane
Data Source
AI summary
A composite membrane for selectively separating (e.g., pervaporating) a first fluid (e.g., first liquid such as a high octane compound) from a mixture comprising the first fluid (e.g., first liquid such as a high octane compound) and a second fluid (e.g., second liquid such as gasoline). The composite membrane includes a porous substrate comprising opposite first and second major surfaces, and a plurality of pores. A pore-filling polymer is disposed in at least some of the pores so as to form a layer having a thickness within the porous substrate. The composite membrane further includes at least one of: (a) an ionic liquid mixed with the pore-filling polymer; or (b) an amorphous fluorochemical film disposed on the composite membrane.