Crosslinked Polyamide Membranes with Covalent Additives
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Solution Overview
Problem
Current water permeable membranes face challenges in achieving high salt rejection and water flux simultaneously, which are essential for effective desalination and other applications.
Innovation Solution
The development of water permeable membranes comprising a crosslinked polyamide layer with nanoparticles and a hydrophilic additive, where the hydrophilic additive covalently bonds to the crosslinked polyamide, enhancing salt rejection and water flux capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional polyamide membranes are used, then salt rejection is achieved, but water flux is limited
Solution Approach 1:
The patent creates a composite polyamide layer incorporating nanoparticles (such as TiO2, SiO2, ZnO) and hydrophilic additives (like PEG, PVP) within the membrane structure. This composite approach allows simultaneous achievement of high salt rejection through the polyamide network and enhanced water flux through the hydrophilic pathways provided by additives and nanoparticle surfaces, directly resolving the contradiction between these two performance parameters.
Solution Approach 2:
The patent applies local quality modification by concentrating hydrophilic additives and nanoparticles at specific locations within the polyamide layer, particularly at the membrane surface and within selective layer pores. This localized enhancement of hydrophilicity creates preferential water transport pathways without compromising the overall salt rejection capability of the polyamide matrix, thereby improving water flux while maintaining reliability.
2Reliability
If membrane density is increased to improve salt rejection, then permeability to water decreases
Solution Approach 1:
The patent utilizes porous nanoparticles (such as mesoporous TiO2 and SiO2) incorporated into the polyamide layer. These porous structures provide internal surface area and hydrophilic pathways that facilitate water transport through the membrane without requiring increased membrane density. The pores act as conduits for water flow while the nanoparticle surfaces enhance hydrophilicity, thereby maintaining high water flux even with a dense polyamide matrix for salt rejection.
Solution Approach 2:
The hydrophilic additives and nanoparticle surfaces serve as intermediary elements between the hydrophobic polyamide matrix and water molecules. These intermediaries create hydrophilic pathways that mediate water transport through the membrane, allowing water to permeate through the dense polyamide structure without direct contact with hydrophobic regions, thus maintaining both salt rejection and water flux performance.
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 membranes exhibit a salt rejection capability of at least 98% and a water flux rate of at least 34 gfd when tested with a 2000 ppm NaCl solution at 225 psi, significantly improving performance compared to membranes without these additives.
Implementation Method 1
The crosslinked polyamide can be interfacially polymerized on the porous support
Implementation Method 2
the hydrophilic additive covalently bonds to the crosslinked polyamide
Implementation Method 3
dissolved substances such as salts can be separated from their solvents, e.g., water, by a procedure known as reverse osmosis
Implementation Method 4
passing the water under pressure through a membrane
Data Source
AI summary
Water permeable membranes and methods of preparation are described. The water permeable membrane can comprise a porous support, and a polyamide layer comprising a crosslinked polyamide on a surface of the porous support, wherein the polyamide layer further comprises nanoparticles and a hydrophilic additive, and wherein the hydrophilic additive covalently bonds to the crosslinked polyamide. The crosslinked polyamide can be interfacially polymerized on the porous support. Methods for desalinating water, performing dialysis, or performing pervaporation using the water permeable membranes are disclosed.