Semipermeable Composite Membrane with Cellulose Nanofibers
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Solution Overview
Problem
Current semipermeable membranes used in seawater desalination and water treatment, such as reverse osmosis membranes, have high environmental impact and limited antifouling properties, necessitating the development of a more sustainable and effective separation technology.
Innovation Solution
A semipermeable composite membrane is created using a porous support coated with a crosslinked polyamide and cellulose nanofibers, which reduces environmental load and enhances water permeation flux and antifouling capabilities by incorporating 0.2-18 mass% cellulose nanofibers with a mean fiber diameter of 3-200 nm, resulting in a 99% NaCl rejection rate and stable water flux over 140 hours with bovine serum albumin exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional aromatic polyamide reverse osmosis membranes are used, then high salt removal performance and water permeability are achieved, but environmental load increases and antifouling properties are limited
Solution Approach 1:
The patent creates a composite membrane by incorporating cellulose nanofibers (0.2-18 mass%) into the aromatic polyamide matrix. This composite structure combines the high salt removal performance of polyamide with the environmental benefits and antifouling properties of cellulose nanofibers, resolving the contradiction between performance and environmental impact
Solution Approach 2:
The patent modifies the membrane composition by introducing cellulose nanofibers with specific diameter ranges (3-200 nm) and controlled content (0.2-18 mass%), changing the physical and chemical parameters of the membrane to achieve both high performance and reduced environmental load
2Reliability
If conventional semipermeable membranes are used, then salt rejection is achieved, but antifouling properties are insufficient leading to flux degradation over time
Solution Approach 1:
The cellulose nanofibers are distributed throughout the membrane structure, creating localized regions with different properties that enhance antifouling characteristics while maintaining overall salt rejection performance
Solution Approach 2:
The composite structure of cellulose nanofiber-reinforced aromatic polyamide provides both high salt rejection and superior antifouling properties, preventing flux degradation and maintaining stable performance over extended operation
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 composite membrane achieves high water permeation flux and salt rejection while reducing environmental impact and fouling, maintaining over 80% initial flux after 140 hours of exposure to organic foulants, with improved surface smoothness and cellulose nanofiber content optimizing antifouling properties.
Implementation Method 1
obtaining a semipermeable composite membrane by making the mixed solution be in contact with a porous support, thereafter, causing a cross-linking reaction of the amine component in the mixed solution, with the amine component adhering to the porous support
Implementation Method 2
causing a cross-linking reaction of the amine component in the mixed solution
Implementation Method 3
a reverse osmosis membrane using an aromatic polyamide and having a pore diameter of 1 nm or less, which makes it possible to remove even ion components such as salts
Data Source
AI summary
The invention provides a semipermeable composite membrane that reduces an environmental load, and a method of producing the semipermeable composite membrane. A semipermeable composite membrane 100 includes, on a porous support 102, a semipermeable membrane 104 containing a crosslinked polyamide 120 and a cellulose nanofiber 110. A method of producing the semipermeable composite membrane includes obtaining a mixed solution containing the cellulose nanofiber 110, water, and an amine component, and obtaining the semipermeable composite membrane 100 by making the mixed solution be in contact with the porous support 102, thereafter, causing a cross-linking reaction of the amine component in the mixed solution, with the amine component adhering to the porous support 102.