Ion Exchangeable Separation Membrane for Field Flow Fractionation
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Solution Overview
Problem
Conventional field flow fractionation apparatuses struggle to effectively separate particles based on diffusion coefficient differences alone, particularly for basic and acidic proteins like lysozyme and bovine serum albumin, which cannot be adequately separated using only diffusion coefficient differences.
Innovation Solution
A field flow fractionation apparatus with a separation channel featuring a semipermeable separation membrane that has ion exchangeable regions with modified functional groups, allowing for ionic interactions between particles and the membrane, enabling separation beyond diffusion coefficient differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separation is performed based only on diffusion coefficient differences, then the apparatus structure remains simple, but separation performance is insufficient for certain particle types
Solution Approach 1:
The separation membrane is modified to have different functional groups at different locations along the channel flow direction. Specifically, the membrane surface is divided into multiple regions with different ion exchange properties (anion exchangeable region, cation exchangeable region, and non-ion exchangeable region), allowing different particle types to interact differently with the membrane at different positions, thereby improving separation performance for particles with similar diffusion coefficients.
Solution Approach 2:
The separation membrane combines multiple functional groups (anion exchange groups and cation exchange groups) on a single membrane structure. This composite membrane design enables simultaneous interaction with both anionic and cationic particles, enhancing the ability to separate diverse particle types including proteins with different charge characteristics that cannot be separated by diffusion coefficient alone.
2Reliability
If ion exchangeable regions are added to the separation membrane, then separation performance improves, but the membrane structure becomes more complex
Solution Approach 1:
The separation membrane is modified to have different functional groups at different locations along the channel flow direction. Specifically, the membrane surface is divided into multiple regions with different ion exchange properties (anion exchangeable region, cation exchangeable region, and non-ion exchangeable region), allowing different particle types to interact differently with the membrane at different positions, thereby improving separation performance for particles with similar diffusion coefficients.
Solution Approach 2:
The separation membrane combines multiple functional groups (anion exchange groups and cation exchange groups) on a single membrane structure. This composite membrane design enables simultaneous interaction with both anionic and cationic particles, enhancing the ability to separate diverse particle types including proteins with different charge characteristics that cannot be separated by diffusion coefficient alone.
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 enhances separation performance by utilizing ionic interactions, allowing for the effective separation of previously difficult-to-separate particles such as basic and acidic proteins, improving the overall separation efficiency.
Implementation Method 1
One of the wall surfaces forming the separation channel is a semipermeable membrane having pores, such as regenerated cellulose (RC) and polyethersulfone (PES), and a porous flat plate called frit is provided outside the semipermeable membrane. This wall surface permeates the carrier fluid introduced into the channel to generate a flow (cross flow) in a direction perpendicular to the forward flow (channel flow)
Implementation Method 2
At least a part of the surface of the separation membrane is an ion exchangeable region in which a functional group having ion exchangeability is modified. This makes it possible to change the interaction caused between sample particles in the separation channel and implement various kinds of separation in accordance with samples.
Implementation Method 3
Sample particles collected by focusing at the boundary portion of a counter current differ in diffusion coefficient due to hydrodynamic radius differences, and hence more diffusible particles are collected on the upper side of the separation channel. This is called relaxation.
Data Source
AI summary
A field flow fractionation apparatus includes a separation channel provided with an inlet port and an outlet port at both ends and forming a space through which a carrier fluid flows between the inlet port and the outlet port, a separation membrane which is a wall surface that defines the separation channel and is parallel to a channel flow in which a carrier fluid flows in the separation channel from the inlet port toward the outlet port, and has a property of permeating the carrier fluid and not permeating particles to be separated, and a discharge port that discharges the carrier fluid having permeated through the separation membrane to outside. At least a part of the surface of the separation membrane is an ion exchangeable region in which a functional group having ion exchangeability is modified.