Reverse Osmosis Membrane Coating for Antifouling and Flux Retention
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Solution Overview
Problem
Existing reverse osmosis membranes lack effective antifouling properties and durability while maintaining water purifying functions, often resulting in reduced salt rejection and permeation flux due to increased thickness from multiple laminated coating layers and complex manufacturing processes.
Innovation Solution
A reverse osmosis membrane with a coating layer comprising a copolymer of an amphoteric ionic compound and glycidyl (meth)acrylate, which forms a chemical bond with the polyamide active layer, enhancing hydrophilicity and preventing fouling material adsorption, thereby maintaining water purifying function and antifouling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple laminated coating layers are applied to improve antifouling properties, then durability is enhanced, but membrane thickness increases and water purifying function deteriorates
Solution Approach 1:
The patent combines multiple functional components (polymerizable monomers with different roles) into a single coating layer that provides both antifouling properties and maintains membrane thinness. The coating layer integrates hydrophilic polymers for antifouling, crosslinking agents for durability, and maintains compatibility with the polyamide active layer, achieving multiple functions in one layer rather than through multiple laminated layers.
Solution Approach 2:
The coating layer uses composite materials consisting of multiple polymer components with different functions: hydrophilic polymers (for antifouling), crosslinking agents (for durability and chemical resistance), and polymerizable monomers (for bonding). This composite structure achieves enhanced antifouling properties and durability while maintaining a single thin layer that does not compromise water purifying function.
2Reliability
If multiple laminated coating layers are applied to improve antifouling properties, then durability is enhanced, but manufacturing process becomes complicated
Solution Approach 1:
The patent merges multiple coating steps into a single coating process where all functional components (hydrophilic polymers, crosslinking agents, polymerizable monomers) are applied simultaneously in one layer. This eliminates the need for multiple sequential coating, drying, and curing steps required by laminated structures, significantly simplifying the manufacturing process while maintaining durability.
Solution Approach 2:
The coating formulation is prepared in advance with all necessary components (polymers, crosslinking agents, monomers) pre-mixed in appropriate ratios. This preliminary preparation allows the coating to be applied as a single ready-to-use solution that self-organizes into a functionally integrated layer, reducing manufacturing complexity compared to applying multiple separate layers.
3Reliability
If a coating layer is applied to enhance antifouling properties, then fouling resistance is improved, but salt rejection and permeation flux may deteriorate
Solution Approach 1:
The patent carefully controls the parameters of the coating layer including thickness (maintaining it thin), crosslinking density (optimizing for balance between durability and permeability), and polymer composition (selecting hydrophilic polymers that resist fouling without blocking pores). By optimizing these parameters, the coating provides antifouling protection while preserving salt rejection and permeation flux.
Solution Approach 2:
The coating layer is designed with local quality differentiation through its composite structure: hydrophilic polymer regions provide antifouling properties on the membrane surface, while the crosslinked network provides mechanical strength and chemical resistance. The coating maintains porosity and hydrophilicity in regions critical for water transport, ensuring that antifouling enhancement does not compromise water purifying function.
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 equivalent or better water purifying performance with improved antifouling properties, including high salt rejection and flux retention even after fouling, without the drawbacks of increased thickness or complex manufacturing.
Implementation Method 1
the coating layer making a chemical bond with the polyamide active layer
Implementation Method 2
enhancing hydrophilicity and preventing fouling material adsorption
Implementation Method 3
When external pressure, having a level higher than the osmotic pressure is applied, the solvent may move toward the solution including the lower concentration of the solute. This phenomenon is known as a reverse osmosis. Various salts and organic materials may be separated by the semi-permeable membrane by using a pressure gradient as a driving force
Implementation Method 4
The phenomenon of a solvent moving between two isolated solutions through a semi-permeable membrane from a solution including a lower concentration of a solute to another solution, including a higher concentration of a solute, is known as an osmotic phenomenon
Data Source
AI summary
A reverse osmosis membrane includes a porous support, a polyamide active layer formed on the porous support, and a coating layer including a copolymer including an amphoteric ionic compound and glycidyl (meth)acrylate. The coating layer makes a chemical bond with the polyamide active layer. A method of manufacturing the reverse osmosis membrane also is disclosed.