Hyper-cross-linked polyamide membrane tunability
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Solution Overview
Problem
Current membrane fabrication processes for nanofiltration are limited by the use of diamines that offer only two reaction sites for cross-linking, restricting the tunability of pore structure and thickness of the polyamide active layer.
Innovation Solution
The development of a hyper-cross-linked polyamide thin film composite nanofiltration membrane using a linear multifunctional aliphatic amine, such as N,N′-bis(3-aminopropyl)ethylenediamine, cross-linked with a hexane-soluble cross-linker like terephthaloyl chloride, allowing for a more tunable and selective membrane structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If diamines with two reaction sites are used for cross-linking, then the membrane fabrication process is simple, but the tunability of pore structure and thickness of the polyamide active layer is restricted
Solution Approach 1:
The patent changes the key parameter of amine functionality from two (diamines) to four (tetramines), enabling hyper-cross-linked networks with improved tunability of pore structure and active layer thickness while maintaining process simplicity through the use of readily hexane-soluble cross-linkers
Solution Approach 2:
The patent creates a composite system combining linear multifunctional aliphatic amines (tetramines) with aromatic acid chlorides (TPC or TMC) to form hyper-cross-linked polyamide networks, achieving enhanced structural tunability and performance
2Manufacturing precision
If conventional diamines are used in interfacial polymerization, then the cross-linking process is straightforward, but the degree of cross-linking and pore structure control is limited
Solution Approach 1:
The patent increases the functionality parameter from 2 to 4 amine groups per molecule, enabling precise control over cross-linking density and pore structure while maintaining ease of manufacture through the selection of hexane-soluble cross-linkers that facilitate simple interfacial polymerization
Solution Approach 2:
The patent utilizes the tetramine cross-linker to create a hyper-cross-linked polyamide network with controlled pore structure, achieving enhanced manufacturing precision in terms of pore size and distribution while maintaining the simplicity of the interfacial polymerization process
3Adaptability or versatility
If multifunctional linear amines are used instead of diamines, then the pore structure tunability is improved, but the device complexity increases
Solution Approach 1:
The patent changes the amine functionality from 2 to 4, creating a hyper-cross-linked network that improves structural tunability while the linear aliphatic structure of the tetramine maintains relative architectural simplicity compared to branched or aromatic alternatives
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 a membrane with improved flux and salt rejection capabilities, with a water flux of 30-40 L m−2 h−1 at 20 bar and salt rejection of 85-100% by weight, while maintaining a cost-effective and simple chemistry process.
Implementation Method 1
The fabrication of the membrane is carried out through interfacial polymerization (IP), where an aqueous solution of an amine is reacted with an acid chloride contained in a non-aqueous (n-hexane) phase
Implementation Method 2
The diamine and TMC react through the Schotten-Baumann reaction leading to a hyper-cross-linked polyamide active layer
Implementation Method 3
A uniformly distributed fine pore structure of the membrane enables the separation of Angstrom-sized molecules
Implementation Method 4
Polyamide membranes have been extensively studied and applied commercially for multivariate applications such as nanofiltration, wastewater treatment, organic solvent nanofiltration, chiral separations, and reverse osmosis
Data Source
AI summary
A filtration membrane includes a thermoplastic substrate, a first layer comprising a polysulfone, a polyvinylpyrrolidone, and a tetramine, and a second layer comprising the tetramine and reacted units of a phthaloyl chloride cross-linked to form a polyamide. A method of preparing the filtration membrane by impregnating tetramine in an ultrafiltration support matrix for rapidly fabricating a hyper-cross-linked polyamide membrane. The membrane prepared by the method of present disclosure can be used for nanofiltration.