Composite Polyamide Membrane Using Tertiary Amine Catalyst
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Solution Overview
Problem
Current composite polyamide membranes for fluid separations, such as reverse osmosis (RO) and nanofiltration (NF), face limitations in salt rejection and permeability, with a need for improved performance additives and treatments to enhance membrane efficiency.
Innovation Solution
A method for forming composite polyamide membranes involves applying a polar solution of polyfunctional amine monomers and a non-polar solution of polyfunctional acyl halide monomers to a porous support, with the addition of an aliphatic, acyclic tertiary amine compound to enhance interfacial polymerization and improve membrane performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional interfacial polycondensation is used to form thin film polyamide layer, then membrane structure is formed, but salt rejection and permeability performance are insufficient
Solution Approach 1:
A phase transfer catalyst (PTC) is introduced as an intermediary substance to facilitate the interfacial polycondensation reaction between polyfunctional amine and polyfunctional acyl halide. The PTC mediates the reaction at the interface between immiscible polar and non-polar solutions, enabling more efficient monomer reaction and formation of a polyamide layer with superior salt rejection and permeability characteristics compared to traditional methods.
Solution Approach 2:
The invention changes the reaction parameters by using a phase transfer catalyst and conducting the reaction in a non-polar solvent system rather than traditional aqueous or polar environments. This parameter change alters the reaction kinetics and polyamide layer formation process, resulting in membranes with improved performance in both salt rejection and permeability.
2Reliability
If complexing agents and polymeric wetting agents are added to coating solutions, then membrane performance may be improved, but formulation complexity increases
Solution Approach 1:
The invention extracts and eliminates the need for multiple complex additives (complexing agents, polymeric wetting agents, acid acceptors, water soluble salts) by using a simplified formulation based on phase transfer catalysis in a non-polar solvent system. This extraction of unnecessary components reduces formulation complexity while maintaining or improving membrane performance.
Solution Approach 2:
The phase transfer catalyst serves multiple functions simultaneously: it facilitates the interfacial reaction, controls the reaction kinetics, and enables the use of a non-polar solvent system. This multi-functionality replaces the need for multiple separate additives, simplifying the overall formulation while achieving improved membrane 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 method results in membranes that effectively reject salts and organic molecules, with increased permeability and salt rejection rates, particularly suited for RO and NF applications, demonstrating improved performance compared to traditional methods.
Implementation Method 1
interfacially polymerizing the monomers to form a thin film polyamide layer
Data Source
AI summary
A method for making a composite polyamide membrane comprising a porous support and a thin film polyamide layer, wherein the method comprises the step of applying a polar solution including a polyfunctional amine monomer and non-polar solution including a polyfunctional acyl halide monomer to a surface of the porous support and interfacially polymerizing the monomers to form a thin film polyamide layer, wherein the method is characterized by the step of applying a non-polar solution comprising an aliphatic acyclic tertiary amine compound to the support.