Composite Membrane Gradient Hydrophilic Support for Desalination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing composite semipermeable membranes for seawater and brine water desalination lack sufficient water permeability and salt removal rates, with previous solutions either compromising on one or the other.
Innovation Solution
A composite semipermeable membrane design featuring a hydrophilic support membrane with a higher concentration of hydrophilic macromolecules on the substrate-side surface, which allows for the formation of a protuberance structure without hindering the separation functional layer's performance, enhancing both water permeability and salt removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrophilic macromolecules are added to the support membrane to improve water permeability, then water permeability increases, but the macromolecules concentrate near the separation functional layer and form a dense layer that prevents protuberance formation, reducing water permeability
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of hydrophilic macromolecules within the support membrane, with higher concentration near the substrate and lower concentration near the separation functional layer. This localized variation allows the membrane to exhibit different properties in different regions: high water permeability near the substrate while maintaining a smooth surface near the separation layer that enables proper protuberance formation.
Solution Approach 2:
The patent uses preliminary action by pre-forming the support membrane with a controlled gradient structure before applying the separation functional layer. The gradient distribution of hydrophilic macromolecules is established in advance during support membrane fabrication, ensuring that when the separation layer is applied, the surface conditions are optimal for protuberance formation without interference from concentrated macromolecules.
2Productivity
If additives are added during interfacial polymerization to enlarge protuberances and increase water permeability, then water permeability increases, but the salt removal rate decreases
Solution Approach 1:
The patent extracts the hydrophilic macromolecules from the separation functional layer formation process and places them exclusively in the support membrane structure. By removing additives from the interfacial polymerization step, the separation layer can form with proper cross-linking and dense structure for salt rejection, while the water permeability enhancement is achieved separately through the support membrane's gradient structure.
Solution Approach 2:
The patent segments the functions of water permeability enhancement and salt removal into two distinct components: the support membrane with gradient hydrophilic macromolecules handles water permeability, while the separation functional layer formed without additives maintains salt removal performance. This functional segmentation allows each layer to optimize its specific role without compromising the other.
3Strength
If the support membrane is made denser to improve structural integrity, then strength increases, but water permeability decreases
Solution Approach 1:
The patent applies parameter changes by modifying the concentration parameter of hydrophilic macromolecules along the thickness direction of the support membrane. The gradient concentration profile (higher near substrate, lower near separation layer) changes the physical parameters of different regions, allowing the bulk to provide structural strength while the surface regions maintain high water permeability and proper morphology for separation layer formation.
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 a high water permeability and salt removal rate, effectively addressing the limitations of previous designs by maintaining the integrity of the separation functional layer while promoting protuberance formation.
Implementation Method 1
a porous support layer having a higher concentration of hydrophilic macromolecules on the substrate-side surface than that on the separation functional layer-side surface
Implementation Method 2
a composite semipermeable membrane useful for selective separation of a liquid mixture... desalination of seawater and brine water
Data Source
AI summary
Provided is a composite semipermeable membrane having a high salt removal rate and a high water permeability. The composite semipermeable membrane comprises a substrate, a porous support layer formed on the substrate, and a separation functional layer formed on the porous support layer, the hydrophilic macromolecule concentration on the substrate-side surface of the porous support layer being higher than that on the separation functional layer-side surface.