Thin-Film Composite Membrane With Extreme pH Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyamide-based thin-film composite membranes are hydrolyzed under extremely acidic and alkaline conditions, limiting their use in treating wastewater and effluent in such environments, and they exhibit low rejection or selectivity for cationic solutes.
Innovation Solution
A cross-linked quaternary ammonium polymer-based selective layer is formed on a porous support through Menshutkin polymerization, providing stability in both extremely acidic and alkaline environments and a positively charged surface for high rejection and selectivity for cationic solutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyamide-based selective layer is used, then separation performance is improved, but stability in extreme pH conditions deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the selective layer from polyamide to crosslinked quaternary ammonium polymer, which fundamentally alters the material's resistance to hydrolysis and enables stability in extreme pH conditions while maintaining separation functionality
Solution Approach 2:
The patent creates a composite structure combining porous support with crosslinked quaternary ammonium polymer selective layer, where the crosslinked network provides chemical stability and the polymer structure maintains separation performance, achieving both reliability and compositional stability
2Reliability
If polyamide-based selective layer is used, then separation performance is improved, but rejection for cationic solutes deteriorates
Solution Approach 1:
The patent inverts the surface charge characteristic from negative (in polyamide) to positive (in quaternary ammonium polymer), which reverses the electrostatic interaction mechanism to achieve high rejection for cationic solutes while preserving overall separation performance
3Reliability
If other selective layer materials are used to enhance acid stability, then acid stability is improved, but alkaline stability deteriorates
Solution Approach 1:
The patent develops a quaternary ammonium polymer-based selective layer that simultaneously achieves both acid stability and alkaline stability, making the membrane universally applicable across extreme pH conditions rather than being optimized for only one condition
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 membrane achieves excellent stability in extreme pH conditions and high cationic solute rejection and selectivity, suitable for water treatment, valuable metal recovery, sewage treatment, and solvent purification, as well as applications like anion-conductive membranes for water electrolysis and fuel cells.
Implementation Method 1
The crosslinked quaternary ammonium structure can have high acid and alkaline stability because it lacks components vulnerable to hydrolysis
Implementation Method 2
because it has a positive surface charge, it can have high rejection and selectivity for cationic solutes
Data Source
AI summary
The present invention relates to a thin-film composite membrane for water treatment and a method for manufacturing same. The selective layer of the thin-film composite membrane according to the present invention is based on a cross-linked quaternary ammonium polymer with high hydrolysis resistance, and thus, excellent stability in both extremely acidic and alkaline conditions may be provided. In addition, the surface of the thin-film composite membrane according to the present invention is positively charged and thus can have high rejection and selectivity for cationic solutes.