Composite Polyamide Membrane Flux via Carboxylic Acid Monomers
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Solution Overview
Problem
The existing composite polyamide membranes used in fluid separations, such as reverse osmosis and nanofiltration, face challenges in improving their performance and selectivity, particularly in rejecting salts and organic molecules, with a need for new additives that enhance their efficiency.
Innovation Solution
A method involving interfacial polymerization between polyfunctional amine and polyfunctional acyl halide monomers, with the inclusion of a subject monomer represented by Formula (III), which is added to the non-polar solution or applied separately to the polyamide layer, enhancing the membrane's properties by incorporating carboxylic acid groups and amine-reactive functional groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyfunctional amine and acyl halide monomers are used for interfacial polymerization, then the membrane forms a basic polyamide structure, but the flux and selectivity performance is insufficient for efficient salt and organic molecule rejection
Solution Approach 1:
The patent incorporates carboxylic acid-containing monomers (such as itaconic acid, fumaric acid, or maleic acid) into the polyamide membrane structure during interfacial polymerization. This creates a composite polyamide material that combines the structural properties of conventional polyamides with the functional properties of carboxylic acid groups, enabling both high flux and enhanced selectivity for salt and organic molecule rejection
Solution Approach 2:
The patent modifies the chemical composition parameters of the polyamide membrane by introducing carboxylic acid functional groups through the use of carboxylic acid-containing monomers. This parameter change alters the membrane's surface charge, hydrophilicity, and pore structure, thereby improving both flux and selectivity performance without compromising structural integrity
2Reliability
If additional monomers are added to improve membrane performance, then flux and selectivity are enhanced, but the complexity of the polymerization system increases
Solution Approach 1:
The patent combines carboxylic acid-containing monomers with conventional polyfunctional amine and acyl halide monomers in a single interfacial polymerization system. This merging of multiple monomer types into one integrated polymerization process allows for simultaneous formation of polyamide structure and carboxylic acid functional groups, enhancing performance while avoiding the need for separate processing steps
3Reliability
If carboxylic acid monomers are incorporated into the polyamide layer, then rejection of salts and organic molecules improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent incorporates carboxylic acid-containing monomers into the polymerization mixture before the interfacial polymerization begins. This preliminary incorporation ensures that the carboxylic acid functional groups are integrated into the polyamide structure during the initial membrane formation process, eliminating the need for subsequent modification steps and simplifying the overall manufacturing process
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 improved flux and selectivity of the composite polyamide membranes, demonstrating increased rejection of salts and organic molecules, as shown in the examples where membranes made with the subject monomer exhibited enhanced performance compared to controls.
Implementation Method 1
interfacial polymerization between polyfunctional amine (e.g. m-phenylenediamine) and poly-functional acyl halide (e.g. trimesoyl chloride) monomers which are sequentially coated upon the support from immiscible solutions
Data Source
AI summary
A method for making a composite polyamide membrane including the steps of applying a polyfunctional amine monomer and 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 includes at least one of the following steps: i) conducting the interfacial polymerization in the presence of a subject monomer comprising at least one carboxylic acid group linked to an aromatic moiety and wherein the aromatic moiety is further substituted with at least one of an acyl halide or anhydride functional group and ii) applying the subject monomer to the thin film polyamide layer. The invention includes many additional embodiments.