Composite Membrane Hydration Layer Antifouling
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Solution Overview
Problem
Existing composite semipermeable membranes struggle to completely inhibit fouling and effectively remove adhered foulants, leading to performance degradation.
Innovation Solution
A composite semipermeable membrane is developed with a supporting membrane and a separation functional layer containing crosslinked polyamide and a hydrophilic polymer with specific oxygen-to-nitrogen ratios, high water content, and acidic groups, bonded by amide bonds, which enhances antifouling properties by forming a hydration layer and promoting foulant removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrophilic polymer is bonded to polyamide by amide bonds to improve antifouling properties, then the ability to inhibit adhesion of membrane-fouling substances is improved, but it is still difficult to completely inhibit fouling and remove adhered foulants
Solution Approach 1:
The invention changes the chemical composition parameters of the separation functional layer by incorporating specific hydrophilic polymers (polyvinyl alcohol, polyacrylic acid, polymethacrylic acid) with defined molecular weights and degrees of saponification. It also controls the weight ratio of polyamide to hydrophilic polymer (1:0.1 to 1:10) and the crosslinking degree (1-50%) to optimize antifouling properties while maintaining permeation performance
Solution Approach 2:
The invention creates a composite separation functional layer combining crosslinked polyamide with hydrophilic polymers. This composite structure integrates the high permeation rate and selectivity of polyamide with the antifouling properties of hydrophilic polymers, achieving synergistic effects that prevent both adhesion and accumulation of foulants
2Reliability
If the separation functional layer includes crosslinked polyamide and hydrophilic polymer, then antifouling properties are improved, but permeation rate may be reduced due to increased layer complexity
Solution Approach 1:
The invention optimizes physical parameters including the thickness of the separation functional layer (controlling it to be thin to maintain permeation), the crosslinking degree (1-50% to balance structure and permeability), and the weight ratio of components (1:0.1 to 1:10) to achieve both high antifouling properties and high permeation rate simultaneously
3Object-affected harmful factors
If foulants adhere to the membrane surface, then membrane performance degrades, but conventional membranes make it difficult to remove adhered foulants
Solution Approach 1:
The invention converts the hydrophilic polymer's strong water interaction capability into a beneficial effect where hydration layers form on the membrane surface, creating a physical barrier that prevents foulant adhesion in the first place, and facilitates easy removal of any adhered substances through the hydrophilic surface properties
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 exhibits improved antifouling properties, maintaining high permeation rates and preventing foulant adhesion, allowing for effective removal of adhered substances and sustained performance.
Implementation Method 1
a hydrophilic polymer which is a polymer of a monomer having an ethylenically unsaturated group... the membrane exhibits improved antifouling properties, maintaining high permeation rates and preventing foulant adhesion
Implementation Method 2
a composite semipermeable membrane including a supporting membrane and a separation functional layer... suitable for use in, for example, desalination of brackish water
Implementation Method 3
a separation functional layer which includes a polyamide and has a hydrophilic polymer bonded to the polyamide by amide bonds
Data Source
AI summary
The present invention relates to a composite semipermeable membrane including: a supporting membrane including a substrate and a porous supporting layer; and a separation functional layer disposed on the porous supporting layer, in which the separation functional layer includes: a crosslinked polyamide; and a hydrophilic polymer which is a polymer of a monomer having an ethylenically unsaturated group, and a surface of the separation functional layer has a ratio of the number of oxygen atoms to the number of nitrogen atoms (O/N ratio), both determined by X-ray photoelectron spectrometry, of 1.5-10, and a standard deviation of the O/N ratio of 0.15 or larger.