Forward Osmosis Membrane Measurement System Using Fluorescent Probes
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Solution Overview
Problem
Conventional methods for measuring concentration polarization in forward osmosis membranes are inaccurate due to the inability to directly measure concentrations on the surface and within the membrane, relying on complex theoretical models that are not well-suited for all applications.
Innovation Solution
A system that continuously measures concentration polarization, mass transfer coefficients, and structural parameters of forward osmosis membranes by maintaining a constant water flux and varying the concentration of the draw solution, allowing for comprehensive analysis of mass transfer variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If theoretical models are used to estimate concentration polarization, then measurement complexity is reduced, but measurement precision deteriorates due to model accuracy dependencies and complex calculations
Solution Approach 1:
The patent introduces an intermediary substance (fluorescent probe or tracers) that can penetrate the membrane and interact with the solute to indirectly measure concentration polarization. This intermediary enables direct measurement without requiring complex theoretical models, resolving the contradiction between measurement simplicity and precision by providing a physically-based direct measurement approach.
Solution Approach 2:
The patent replaces complex theoretical calculation systems with direct physical measurement systems using fluorescent probes or tracer substances. Instead of relying on mathematical models to estimate concentration polarization, the system uses optical detection or radioactive/tracer detection to directly measure the concentration distribution within the membrane and at the membrane surface, thereby eliminating model dependency and improving measurement precision.
2Measurement precision
If direct measurement of concentration polarization is attempted, then measurement precision improves, but device complexity increases due to the need to measure concentrations on membrane surface and within support layer
Solution Approach 1:
The patent employs intermediary substances (fluorescent probes, tracers) that can penetrate the membrane structure and interact with the solute to enable measurement of concentration polarization. These intermediaries serve as measurable proxies for the difficult-to-measure solute concentration distribution, allowing direct measurement of both external and internal concentration polarization without requiring complex measurement systems.
Solution Approach 2:
The patent utilizes fluorescent probes that undergo color or fluorescence intensity changes in response to interactions with the solute or changes in their local chemical environment. This optical signal change enables non-invasive, direct detection of concentration polarization at the membrane surface and within the support layer, simplifying the measurement system while improving precision through optical detection methods.
3Measurement precision
If multiple separate experiments are conducted to measure different mass transfer parameters, then measurement precision improves for each parameter, but loss of time increases due to multiple experimental runs
Solution Approach 1:
The patent designs a universal measurement system that can simultaneously determine multiple mass transfer parameters (water flux, solute flux, concentration polarization, mass transfer coefficients) through a single integrated experiment. By using multiple tracers or fluorescent probes with different properties that can be detected simultaneously, the system eliminates the need for separate experiments for each parameter, thereby reducing time loss while maintaining precision through comprehensive measurement.
Solution Approach 2:
The patent implements continuous measurement techniques where tracers or fluorescent probes remain in the system throughout the experiment, allowing simultaneous measurement of multiple parameters over time. This continuous action enables the system to capture dynamic mass transfer behavior and determine multiple parameters from a single ongoing experiment rather than requiring multiple discrete experimental runs, thereby reducing total experimental time while maintaining data precision.
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 approach reduces measurement uncertainty, simplifies the relationship between water flux and surface concentration, and enables accurate measurement of mass transfer coefficients and diffusion coefficients over a broad concentration range, saving time and cost.
Implementation Method 1
Forward osmosis water treatment is based on spontaneous osmosis in which when a semipermeable membrane is placed between two solutions of different concentrations, water moves across the membrane due to the concentration difference
Implementation Method 2
a feed solution supply pump supplying the feed solution from the feed solution storage tank to the feed solution reservoir at a fixed flow rate corresponding to a water flux across the membrane such that the water flux is maintained constant
Implementation Method 3
a draw solution circulating pump circulating the draw solution such that the draw solution is circulated from the draw solution storage tank through the draw solution reservoir
Implementation Method 4
the permeation of water across the membrane causes concentration polarization (CP) on the surface of the membrane and in the porous support layer
Data Source
AI summary
Disclosed is a system for measuring mass transfer in a membrane and solutions. The system includes: a membrane module 10 including a feed solution reservoir 11 accommodating a feed solution f, a draw solution reservoir 13 accommodating a draw solution d whose osmotic concentration is higher than that of the feed solution f, and a holder 15 supporting a semipermeable membrane m arranged between the feed solution reservoir 11 and the draw solution reservoir 13 and whose performance is to be measured; a feed solution storage tank 20 storing the feed solution f; and a feed solution supply pump 30 supplying the feed solution f from the feed solution storage tank 20 to the feed solution reservoir 11 at a fixed flow rate corresponding to a water flux WF across the membrane m such that the water flux WF is maintained constant.