CNT-Immobilized Membrane Pores for Higher Solute Selectivity
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Solution Overview
Problem
Current membrane technologies face challenges in efficiently incorporating carbon nanotubes (CNTs) without encapsulating them in polymers, which hinders their active surface availability for solute transport and reduces membrane performance in separation processes.
Innovation Solution
The method involves immobilizing functionalized carbon nanotubes within the pore structure of polymeric membranes or substrates without encapsulation, using techniques like dispersion and pressure injection, allowing the CNT surface to remain accessible for solute exchange, and utilizing them in various separation processes such as membrane distillation and gas separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If carbon nanotubes are incorporated into polymeric membranes using conventional mixed matrix membrane fabrication processes, then the membrane structure is formed, but the carbon nanotube active surface is encapsulated by the polymer coating, reducing solute transport efficiency
Solution Approach 1:
The patent applies preliminary action by first forming the porous polymeric membrane structure, then introducing carbon nanotubes into the pores after membrane formation. This reverse sequence prevents polymer encapsulation of CNT surfaces, as the CNTs are placed into pre-formed pores rather than being embedded during membrane fabrication. The CNTs are introduced as suspensions or dispersions that fill the pores and are then immobilized through drying or crosslinking, ensuring surface accessibility is preserved.
Solution Approach 2:
The patent extracts the carbon nanotube introduction step from the conventional simultaneous fabrication process. Instead of adding CNTs to polymer solution before casting, the method separates membrane formation and CNT incorporation into distinct sequential steps: first form the membrane, then introduce CNTs into the formed membrane pores. This extraction eliminates the encapsulation problem caused by polymer coating during conventional fabrication.
2Ease of manufacture
If carbon nanotubes are added to polymer solution followed by film casting to create mixed matrix membranes, then the membrane is fabricated, but the process is complex, time consuming, and requires strong polymer-CNT interactions that lead to encapsulation
Solution Approach 1:
The patent segments the membrane fabrication process into distinct independent steps: (1) membrane formation, (2) CNT suspension preparation, (3) CNT introduction into pores, and (4) CNT immobilization. This segmentation simplifies each individual step and eliminates the need for complex simultaneous processing required in conventional MMM fabrication, reducing overall fabrication time while improving CNT surface accessibility.
Solution Approach 2:
The patent uses pore-filling suspensions or dispersions as intermediaries to introduce carbon nanotubes into the membrane pores. Rather than requiring direct polymer-CNT interactions during casting, the CNTs are delivered via a liquid carrier medium that fills the pores and can be subsequently removed or dried, leaving immobilized CNTs without polymer encapsulation. This intermediary approach simplifies the fabrication process.
3Strength
If conventional mixed matrix membrane processes are used, then membranes are fabricated, but strong interactions between polymer and inorganic filler are required, coating the particle surface and reducing active surface area
Solution Approach 1:
The patent extracts the CNT introduction from the polymer matrix formation process, eliminating the need for strong polymer-CNT interactions. By introducing CNTs into pre-formed pores rather than mixing them into polymer solution, the method avoids the requirement for strong interfacial adhesion, thereby preventing polymer coating of the CNT surface and preserving active surface area for solute transport.
Solution Approach 2:
The patent utilizes the porous structure of the polymeric membrane as the incorporation medium for carbon nanotubes. The pores provide physical spaces that accommodate CNTs without requiring chemical or strong physical interactions between polymer and CNT. The porous architecture allows CNTs to be positioned within pores while maintaining surface accessibility, eliminating the need for strong polymer-filler interactions that would otherwise be required for particle stabilization.
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 enhances the membrane's performance by increasing solute flux and selectivity, with enrichment factors up to 200% in liquid phase extractions, and improves solvent retention, demonstrating a significant improvement over traditional methods.
Implementation Method 1
CNTs are typically also effective sorbents, particularly for organics. Together these two properties may increase the selective partitioning and permeation of the solute of interest. In typical membrane-based liquid extractions, when the two phases contact at the pores, the interactions can take place via rapid solute exchange on the CNTs
Implementation Method 2
CNTs have been deposited on ceramic matrices via chemical vapor deposition to form membranes that exhibit high permeation rates. Aligned MWNTs have facilitated the flow of small organic molecules. Theoretical studies have suggested that permeabilities of certain liquids and gases through carbon nanotubes far exceed what is expected from classical diffusion models
Implementation Method 3
membranes are permeable structures that facilitate the separation of solutes based on size and/or physical and chemical properties
Implementation Method 4
permeabilities of certain liquids and gases through carbon nanotubes far exceed what is expected from classical diffusion models
Implementation Method 5
introducing a plurality of carbon nanotubes into the substrate
Data Source
AI summary
The present disclosure provides an improved membrane or substrate having carbon nanotubes introduced and/or immobilized therein, and an improved method for introducing and/or immobilizing carbon nanotubes in membranes or substrates. More particularly, the present disclosure provides for improved systems and methods for fabricating membranes or substrates having carbon nanotubes immobilized therein. In one embodiment, the present disclosure provides for systems and methods for introducing and/or immobilizing functionalized carbon nanotubes into the pore structure of a polymeric membrane or substrate, thereby dramatically improving the performance of the polymeric membrane or substrate. In exemplary embodiments, the present disclosure provides for systems and methods for the fabrication of nanotube immobilized membranes by incorporating CNTs in a membrane or substrate.