Polyamide Membrane Passivation Layer for Antifouling
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Solution Overview
Problem
Current polyamide water treatment separation membranes face challenges with insufficient antifouling properties, leading to decreased permeation flux and potential secondary pollution due to fouling, which existing hydrophilic coatings do not adequately address.
Innovation Solution
A passivation layer is formed using an aqueous solution containing an amine group-containing compound, an epoxy group-containing compound, and a fluorine-containing compound, which reacts to produce specific compounds that enhance the antifouling properties of the polyamide membrane by reducing fouling material absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrophilic polymer coating such as polyvinyl alcohol is applied on the polyamide layer surface, then the membrane shows improved hydrophilicity, but the antifouling effect against hydrophilic fouling materials remains insufficient
Solution Approach 1:
The patent applies a composite coating layer comprising multiple components: polyvinyl alcohol (PVA) as the base hydrophilic polymer, silane-modified PVA for enhanced crosslinking and stability, and fluorinated compounds for additional antifouling properties. This multi-component composite structure synergistically improves antifouling performance while maintaining permeation flux, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the coating layer through controlled crosslinking reactions using silane groups and fluorinated compounds. By adjusting crosslinking density, hydroxyl group content, and fluorine compound concentration, the membrane achieves optimal balance between antifouling properties and water permeability, transforming the coating from a simple hydrophilic layer to a functionally optimized multifunctional barrier.
2Quantity of substance
If the membrane operates for extended periods, then water treatment capacity increases, but fouling accumulates leading to decreased permeation flux and secondary pollution
Solution Approach 1:
The patent applies preliminary anti-action by pre-coating the polyamide layer with a specially designed composite layer containing PVA, silane-modified PVA, and fluorinated compounds before the membrane encounters fouling materials. This pre-established protective barrier prevents fouling accumulation and secondary pollution from the outset, allowing extended operation without performance degradation. The crosslinked structure with hydroxyl groups and fluorinated segments creates a surface that resists adsorption of organic and inorganic fouling materials.
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 solution significantly reduces fouling effects, maintaining high permeation flux and salt rejection rates, with a 5% or less decrease in flux after 6 hours of exposure to a fouling solution, demonstrating excellent antifouling performance.
Implementation Method 1
a passivation layer formed on the polyamide layer by using an aqueous solution including an amine group-containing compound, an epoxy group-containing compound, and a fluorine-containing compound wherein the passivation layer including at least one compound produced by reactions between the amine group-containing compound, the epoxy group-containing compound and the fluorine-containing compound
Implementation Method 2
Osmosis occurs when two solutions of different concentrations are separated by a semipermeable membrane, and solvent flows from a solution having a lower concentration of solute through the membrane to another solution having a higher concentration of solute
Implementation Method 3
When an external pressure higher than the osmotic pressure is applied to the higher concentration side, the solvent may move from the solution having the higher concentration of the solute to the solution having the lower concentration of the solute. This phenomenon is known as reverse osmosis
Data Source
AI summary
A water treatment separation membrane includes a support having pores, a polyamide layer formed on the support, and a passivation layer formed on the polyamide layer by using an aqueous solution including an amine - containing compound, an epoxy group-containing compound and a fluorine-containing compound.