Nitrous Acid Post-Treated Polyamide Membrane
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Solution Overview
Problem
Current composite polyamide membranes for fluid separations, such as reverse osmosis and nanofiltration, face challenges in achieving optimal performance due to limitations in salt rejection and flux, necessitating the development of new combinations of monomers and post-treatments to enhance membrane properties.
Innovation Solution
A method involving the application of a polar solution with a polyfunctional amine monomer and a non-polar solution with a polyfunctional acyl halide monomer for interfacial polymerization on a porous support, followed by treatment with a polyfunctional arene compound and exposure to nitrous acid, incorporating a tri-hydrocarbyl phosphate compound and an acid-containing monomer to form a thin film polyamide layer with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interfacial polycondensation is used to form thin film polyamide layer, then membrane structure is formed, but salt rejection and flux performance are insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition and structure of the polyamide layer through controlled hydrolysis of acyl halide groups to carboxylic acid groups, and by adjusting the ratio of different monomers (trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride) to optimize both salt rejection and flux performance
Solution Approach 2:
The patent creates a composite membrane structure combining a porous support layer with a thin film polyamide layer containing specific functional groups (carboxylic acid, amine, hydroxyl) in controlled ratios, achieving enhanced performance through the synergistic combination of different material properties
2Reliability
If polyamide layer is made denser to improve salt rejection, then permeability decreases
Solution Approach 1:
The patent applies local quality by creating specific functional group distributions within the polyamide layer, concentrating carboxylic acid groups at strategic locations to enhance salt rejection while maintaining channels for water permeability through controlled hydrolysis and monomer selection
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 composite polyamide membranes with enhanced salt rejection and flux performance, specifically rejecting over 95% of monovalent salts and organic molecules, while maintaining high permeability, thereby improving membrane efficiency in fluid separation applications.
Implementation Method 1
applying a polar solution comprising a polyfunctional amine monomer and a non-polar solution comprising a polyfunctional acyl halide monomer to a surface of a porous support and interfacially polymerizing the monomers to form a thin film polyamide layer
Implementation Method 2
exposing the thin film polyamide layer to nitrous acid
Data Source
AI summary
A method for making a composite polyamide membrane including a porous support and a thin film polyamide layer, wherein the method includes: (i) applying a polar solution comprising a polyfunctional amine monomer and a non-polar solution comprising a polyfunctional acyl halide monomer to a surface of a porous support and interfacially polymerizing the monomers to form a thin film polyamide layer; (ii) treating the thin film polyamide layer with a polyfunctional arene compound; and (iii) exposing the thin film polyamide layer to nitrous acid; wherein the polar and non-polar solutions further comprises at least one of the following: (A) at least one of the solutions further comprises a tri-hydrocarbyl phosphate compound represented by Formula (I): and (B) the non-polar solution further comprises an acid-containing monomer comprising a C2―C20 hydrocarbon moiety substituted with at least one carboxylic acid functional group or salt thereof and at least one amine-reactive functional group.