Reverse Osmosis Membrane Damage Detection via Permeate-Side Staining
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Solution Overview
Problem
Existing methods for inspecting physical damage on reverse osmosis membranes struggle to distinguish between damaged and undamaged areas due to staining from scales, foulants, and oxidative deterioration of the membrane's polyamide layer.
Innovation Solution
A damage inspection method that involves staining the reverse osmosis membrane with a solution containing a staining agent, washing the membrane to remove excess solution, and then inspecting the permeate side for stained areas to determine the presence and extent of physical damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a staining solution is cross-flowed on the skin layer side of the reverse osmosis membrane to inspect physical damage, then the inspection method is simple and quick, but the ability to distinguish between damaged and undamaged portions deteriorates due to staining from scales, foulants, and oxidative deterioration of the polyamide layer
Solution Approach 1:
The patent applies the inversion principle by switching from staining the skin layer side (supply side) to staining the permeate side (permeate side) of the membrane. This reverses the conventional approach and allows the staining solution to penetrate through damaged areas from the permeate side, making damaged portions visible without being obscured by scales, foulants, or oxidative deterioration on the supply side. The permeate side staining enables clear distinction between damaged and undamaged areas while maintaining operational simplicity.
2Reliability
If the membrane is stained to identify damaged areas, then physical damage can be detected, but the entire functional layer may be stained due to oxidative deterioration of polyamide, making it difficult to distinguish damaged from undamaged portions
Solution Approach 1:
The patent extracts the staining function from the supply side (skin layer) and relocates it to the permeate side. By applying the staining solution to the permeate side, only the damaged portions of the membrane allow the stain to penetrate through to the supply side, while the intact functional layer remains unstained. This extraction of the staining process to a different location eliminates the problem of entire functional layer staining and preserves information about damaged portions.
Solution Approach 2:
The patent uses the membrane itself as an intermediary that selectively allows staining solution to pass through. The membrane acts as a filter where only damaged areas permit stain penetration from the permeate side to the supply side. This intermediary function of the membrane enables selective staining of damaged portions without staining the entire functional layer, even in the presence of oxidative deterioration.
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
This method allows for a simple, quick, and accurate assessment of membrane surface damage and damage factors, enabling timely measures to maintain stable membrane operation and ensure fresh water production.
Implementation Method 1
a water production method that obtains desalted water by applying a pressure higher than an osmotic pressure to water containing solutes such as salts so that the water permeates the reverse osmosis membrane
Implementation Method 2
supplying water-to-be-treated including a staining agent to the reverse osmosis membrane to stain the reverse osmosis membrane... at least one of: presence or absence of physical damage; and a degree of physical damage in the reverse osmosis membrane is inspected based on presence or absence of a stained area on at least a permeate side of the stained membrane
Data Source
AI summary
The present invention relates to a damage inspection method for a reverse osmosis membrane, in which at least one of: presence or absence of physical damage; and a degree of physical damage in a reverse osmosis membrane is inspected based on presence or absence of a stained area on at least a permeate side of a stained membrane obtained by supplying a water-to-be-treated including a staining agent to the reverse osmosis membrane to stain the reverse osmosis membrane.