Folded Semipermeable Membrane for High-Pressure Desalination
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Solution Overview
Problem
Existing composite semipermeable membranes face challenges in achieving both high water production performance and desalination performance, especially during high-pressure operations.
Innovation Solution
A composite semipermeable membrane design featuring a support membrane with a separation functional layer that includes a thin membrane with a fold structure, characterized by specific protrusion heights, angles, and ratios, as well as a thickness of 15 nm or more, enhancing water permeability and salt removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thin membrane thickness is reduced to improve water production performance, then water permeability increases, but desalination performance deteriorates
Solution Approach 1:
The invention transitions from a flat two-dimensional membrane structure to a three-dimensional folded structure. The thin membrane is folded to form protrusions with heights of 10-500 nm, creating additional separation paths and maintaining effective separation distance even when the base membrane thickness is reduced to 15 nm or more. This dimensional transformation allows the membrane to achieve both high water permeability and effective salt rejection.
Solution Approach 2:
The invention creates a nested structure where the thin membrane is folded within itself to form protrusions. The membrane folds back on itself multiple times, creating a compact nested arrangement that increases the effective path length for salt rejection while maintaining a thin overall profile. This nested folding allows the membrane to pack separation functionality into a minimal thickness.
2Reliability
If the thin membrane thickness is increased to improve desalination performance, then salt removal efficiency increases, but water production performance deteriorates
Solution Approach 1:
Instead of increasing the base membrane thickness, the invention folds the thin membrane to create protrusions that extend 10-500 nm from the membrane surface. This vertical dimensional addition provides the necessary separation path length for effective desalination without compromising water permeability, as the folded structure maintains close proximity to the support membrane for efficient water transport.
Solution Approach 2:
The membrane protrusions exhibit curved, rounded shapes rather than sharp angular folds. This curvature optimizes the flow paths for water molecules while maintaining structural integrity. The rounded protrusion shapes reduce stress concentration and facilitate smooth water flow, balancing desalination effectiveness with water production efficiency.
3Productivity
If high-pressure operation is applied to improve water production, then permeation flux increases, but membrane performance stability deteriorates
Solution Approach 1:
The invention creates local quality variations through the folded protrusion structure, where different regions of the membrane have specialized functions. The protrusions provide enhanced salt rejection zones, while the regions adjacent to the support membrane maintain high water permeability. This local differentiation allows the membrane to withstand high pressures while maintaining stable performance across different operational zones.
Solution Approach 2:
The invention creates a composite structure combining the thin folded membrane with the support membrane. The support membrane provides mechanical strength and pressure resistance, while the folded thin membrane layer provides selective separation functionality. This composite architecture enables the system to operate stably under high pressure conditions while maintaining excellent water production and desalination performance.
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 excellent water production and desalination performance even under high-pressure conditions, maintaining high permeability and salt removal rates.
Implementation Method 1
a composite semipermeable membrane including a support membrane and a separation functional layer provided on the support membrane, in which the separation functional layer includes a thin membrane with a fold structure
Implementation Method 2
use of a membrane separation method as a process for energy and resource conservation has expanded. Membranes used in the membrane separation method include a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane
Implementation Method 3
the thin membrane has a fold structure including a plurality of protrusions, an actual length L of the thin membrane per 1 μm length of the support membrane in a cross-sectional direction perpendicular to a membrane surface is 3.0 μm or more
Data Source
AI summary
The present invention relates to a composite semipermeable membrane including: a support membrane; and a separation functional layer provided on the support membrane, in which the separation functional layer includes a thin membrane, the thin membrane has a fold structure including a plurality of protrusions, an actual length L of the thin membrane per 1 μm length of the support membrane in a cross-sectional direction perpendicular to a membrane surface is 3.0 μm or more, and a thickness of the thin membrane in the protrusion is 15 nm or more.