Polyamide Membrane Antioxidant Oxidation Resistance
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Solution Overview
Problem
Polyamide water-treatment separation membranes are prone to degradation due to sensitivity to oxidizing materials and chlorine, leading to reduced salt rejection rates and short lifespan, necessitating frequent replacements and increased treatment costs.
Innovation Solution
Incorporating an antioxidant, specifically bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, into the polyamide layer during interfacial polymerization with an acyl halide compound to enhance oxidation and chlorine resistance, without the need for additional post-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyamide composite membranes are used for water treatment, then salt rejection rate and pH stability are improved, but oxidation resistance and chlorine resistance deteriorate leading to short lifespan
Solution Approach 1:
The patent applies preliminary action by incorporating antioxidants (such as hindered phenols, hindered amines, or phosphorus-containing compounds) into the polyamide layer during the membrane fabrication process. This preliminary incorporation of protective agents prevents oxidation and chlorine degradation before the membrane is put into service, thereby extending membrane lifespan while maintaining salt rejection performance
Solution Approach 2:
The patent employs composite materials by combining polyamide with antioxidant compounds to create a multi-functional membrane material. The composite structure integrates the salt rejection capability of polyamide with the oxidation resistance of antioxidant additives, resolving the contradiction between reliability and durability
2Reliability
If the active layer surface area is increased to improve chlorine resistance, then oxidation resistance is improved, but transmittance decreases due to positive charge attachment
Solution Approach 1:
The patent uses antioxidants as intermediary substances that mediate between the polyamide matrix and chlorine/oxidizing agents. These intermediary compounds scavenge free radicals and prevent direct attack on the polyamide chains, improving chlorine resistance without altering surface charge properties that would cause contaminant attachment
Solution Approach 2:
The patent changes the chemical composition parameters of the polyamide layer by incorporating specific antioxidant compounds with controlled concentrations. This parameter modification enhances oxidation resistance through chemical protection mechanisms rather than physical surface area expansion, avoiding the transmittance reduction problem
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 superior oxidation and chlorine resistance, maintaining high salt rejection rates and permeate flux over time, even when exposed to challenging water conditions containing sodium hypochlorite, thereby extending its lifespan and reducing replacement frequencies.
Implementation Method 1
a polyamide layer formed on the porous support, and the polyamide layer contains an antioxidant having a solubility parameter value of 9(J/cm³) or less
Implementation Method 2
the polyamide layer contains an antioxidant having a solubility parameter value of 9(J/cm³) or less, thereby providing a water-treatment separation membrane having superior oxidation resistance and chlorine resistance properties
Implementation Method 3
the reverse osmosis method may be a desalinization process using a semipermeable membrane enabling water to penetrate therethrough while not allowing salts to penetrate therethrough
Implementation Method 4
a porous support and a polyamide layer formed on the porous support
Data Source
AI summary
The present disclosure relates to a water-treatment separation membrane including: a porous support and a polyamide layer formed on the porous support, wherein the polyamide layer contains an antioxidant having a solubility parameter value of 9 (J/cm3)1/2 to 22 (J/cm3)1/2, and a method of manufacturing the same.