Charged Hydrogel–Polyamide Double-Network RO Membranes for Ion Rejection
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Solution Overview
Problem
Existing reverse osmosis membranes require multiple-step reactions and suffer from insufficient bonding strength between structural and functional layers, leading to suboptimal salt separation performance and anti-fouling capabilities.
Innovation Solution
A method is developed to construct a charged hydrogel polyamide double network on the membrane surface through interface-initiated free radical polymerization, enhancing electrical properties and hydrophilicity to limit ion passage and improve water transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple-step reactions are used to construct polyamide structure and improve salt separation performance, then salt separation performance is improved, but the production process becomes complex and bonding strength between layers is insufficient
Solution Approach 1:
The patent combines the construction of polyamide structure and hydrogel layer into a single-step interface-initiated free radical polymerization reaction. The aqueous phase polymer solution containing monomers and crosslinking agents reacts at the interface with the base membrane to simultaneously form both the polyamide separation layer and hydrogel functional layer, eliminating the need for multiple separate reaction steps while ensuring strong bonding between layers.
Solution Approach 2:
The patent creates a composite membrane structure by integrating polyamide and hydrogel materials through a single reaction step. The resulting membrane contains both the polyamide network for salt separation and the hydrogel network for hydrophilicity and anti-fouling properties, with strong interlayer bonding achieved through the shared interface polymerization process.
2Reliability
If multiple-step reactions are used to construct functional layers, then anti-fouling performance is improved, but the number of reaction steps increases and bonding strength is insufficient
Solution Approach 1:
The patent merges the formation of anti-fouling hydrogel layer and salt separation polyamide layer into one simultaneous reaction step. The aqueous phase polymer solution contains both monomers for polyamide formation and crosslinking agents for hydrogel formation, which react together at the membrane interface to create both functional layers with strong bonding in a single operation.
Solution Approach 2:
The patent controls the reaction parameters of the aqueous phase polymer solution (composition, concentration, reaction conditions) to simultaneously achieve the desired polyamide structure for salt separation and hydrogel structure for anti-fouling properties. By adjusting these parameters, both functional layers are formed with optimal properties in a single reaction step.
3Manufacturing precision
If charged hydrogel is introduced to enhance electrical properties and limit ion passage, then salt separation performance is improved, but the complexity of membrane construction increases
Solution Approach 1:
The patent combines the introduction of charged hydrogel with the construction of polyamide structure in a single interface-initiated free radical polymerization reaction. The aqueous phase polymer solution contains monomers with ionic groups that form both the polyamide network and the charged hydrogel network simultaneously, achieving enhanced electrical properties and salt separation performance without requiring separate steps to introduce the hydrogel component.
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 resulting membrane exhibits improved salt and water separation performance, enhanced anti-fouling properties, and simplified production process with reduced material and equipment requirements.
Implementation Method 1
construct a charged hydrogel polyamide double network layer on the membrane surface through an interface-initiated free radical polymerization reaction
Implementation Method 2
the electrical properties of the membrane are enhanced by the presence of the charged hydrogel, thereby limiting the dissolution of ions in water on the membrane surface and the diffusion of ions in the membrane
Implementation Method 3
the hydrogel improves the hydrophilicity of the membrane, which is beneficial to the transmission of water molecules in the membrane
Data Source
AI summary
A method of preparing reverse osmosis membrane with double network of charged hydrogel and polyamide includes the steps of: (a) preparing an aqueous phase polymer solution containing m-phenylenediamine, polymer monomer with ionic group and crosslinking agent, and an organic phase polymer solution containing trimesoyl chloride and photoinitiator; (b) preparing a reverse osmosis membrane by inducing reaction of the aqueous phase and the organic phase polymer solution under ultraviolet light to form a charged hydrogel layer and a polyamide layer respectively; and (c) cleaning the membrane. The hydrogel layer not only enhances the electrical properties, thereby limiting the dissolution of ions in water on the membrane surface and the diffusion of ions in the membrane, and reducing the ions passing through the membrane, but also improves the hydrophilicity, which is beneficial to the transmission of water molecules within the membrane and the improvement of the anti-fouling performance of the membrane.