Amino Acid-Modified Polyamide Membrane for High Flux
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Solution Overview
Problem
Polyamide composite membranes face challenges in achieving high water flux while maintaining a high interception rate, as traditional additives often have limited effect at low concentrations and can destabilize the membrane solution at higher concentrations, leading to reduced performance.
Innovation Solution
Incorporating an amino acid as an end-capping reagent in the polyamine solution during interface polymerization to regulate the polyamide layer's structure, decrease cross-linking, and enhance hydrophilicity, thereby improving water permeability and flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional hydrophilic additives (amine salt, isopropanol) are added to increase water flux, then water permeability improves, but membrane stability deteriorates at large addition amounts
Solution Approach 1:
The patent changes the chemical nature of the additive from traditional hydrophilic compounds (amine salt, isopropanol) to amino acid compounds. This parameter change allows achieving high water flux through the hydrophilic carboxyl and amino groups of amino acids, while the zwitterionic structure maintains solution stability even at higher concentrations (0.1-10% w/v), resolving the contradiction between flux improvement and stability maintenance
Solution Approach 2:
Amino acid compounds act as an intermediary substance that mediates between the conflicting requirements of high water flux and solution stability. The amino acid's dual functional groups (carboxyl and amino) provide hydrophilicity for enhanced flux while its zwitterionic character prevents solution destabilization, serving as a bridge between these opposing needs
2Manufacturing precision
If the active separation layer is made more compact to increase salt interception rate, then interception capacity improves, but water flux decreases
Solution Approach 1:
The patent applies local quality modification by introducing amino acid compounds specifically into the active separation layer formation process. The amino acids locally modify the polyamide layer structure by competing with polyamine for acyl chloride, creating localized hydrophilic channels and reducing cross-linking density in specific regions, thereby achieving both high interception and high flux simultaneously
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 amino acid-modified polyamide composite membrane exhibits increased water flux by 50% to 75% with minimal impact on salt interception rate, reducing energy consumption and production costs while maintaining membrane stability.
Implementation Method 1
a polyamide separation layer on a non-woven polysulfone fabric supporting layer through an interface polymerization reaction
Implementation Method 2
the amino acid is used as an end-capping reagent to react with acyl chloride groups
Implementation Method 3
carboxyl contained in the amino acid can improve the hydrophilicity of a membrane
Implementation Method 4
the more compact the active separation layer is, the larger the resistance to the water molecules is, and the higher the interception capacity to salt ions is
Data Source
AI summary
The present invention provides a high-flux polyamide composite membrane, which includes a composite membrane body, wherein the composite membrane body includes a non-woven fabric, a porous supporting layer and a polyamide layer which are successively arranged; and the polyamide layer is prepared by a polyamine solution and a poly-acyl chloride solution through an interface polymerization reaction, wherein the polyamine solution contains amino acid. The amino acid adopted in the technical solution of the present invention can be used as an end-capping reagent to react with acyl chloride groups, thereby regulating a polyamide layer structure, decreasing a cross-linking degree of the polyamide layer, and opening a channel for the passing of water molecules; and moreover, the hydrophilic performance of a membrane surface can also be improved, and a water flux is increased while a high interception rate is ensured.