Sub-Millimetre Counter-Current Liquid Extraction via Alternating Pressure
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Solution Overview
Problem
Existing counter-current liquid-liquid extraction methods in sub-millimetre conduits face performance limitations due to mechanical integrity issues with membranes and reduced mass transfer efficiency, especially with miniaturization, making them inefficient for quantitative extraction.
Innovation Solution
A method involving alternating pressure gradients to generate visco-inertial and viscous-capillary flows in a sub-millimetre conduit, displacing liquid drops in counter-current fashion to maintain a stable interface and enhance extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a membrane is used to separate liquid phases in counter-current extraction, then phase separation is maintained, but mass transfer efficiency is reduced due to membrane resistance and pressure limitations
Solution Approach 1:
The invention removes the membrane component entirely from the system. Instead of using a membrane to separate phases, the patent employs a packed bed of inert particles where phases are separated by gravity and flow dynamics. This elimination of the membrane eliminates the resistance to mass transfer while maintaining phase separation through alternative mechanisms.
Solution Approach 2:
The invention introduces a packed bed of inert particles as an intermediary medium. This packed bed serves as the separation medium instead of a membrane, allowing phases to flow counter-currently while maintaining separation through the physical structure of the packing and gravity, without the mass transfer resistance inherent in membranes.
2Quantity of substance
If the conduit size is reduced for miniaturization, then liquid volumes are reduced and containment is improved, but mass transfer efficiency decreases due to reduced surface area to volume ratio
Solution Approach 1:
The invention segments the continuous liquid phases into discrete droplets that flow through the packed bed. This segmentation creates numerous small liquid-gas interfaces throughout the conduit, dramatically increasing the effective surface area for mass transfer relative to the total liquid volume. The droplet formation and distribution within the packed bed structure compensates for the reduced overall conduit dimensions.
Solution Approach 2:
The invention uses a packed bed of porous or particulate inert material as the extraction medium. This porous structure provides extensive surface area within a compact volume, enhancing mass transfer efficiency despite the miniaturized conduit size. The packing material creates numerous flow paths and contact points between phases, maintaining high surface area to volume ratios.
3Device complexity
If co-current flow is used for extraction, then device complexity is reduced, but extraction efficiency is limited and cannot achieve quantitative transfer
Solution Approach 1:
The invention inverts the conventional approach by using counter-current flow instead of co-current flow. The mobile phase and stationary phase move in opposite directions through the packed bed, maximizing the concentration gradient throughout the entire contact length. This inversion of flow direction enables quantitative extraction efficiency while maintaining relatively simple device architecture through the use of a single packed bed column.
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 method achieves high extraction performance with a stable interface and increased surface area, suitable for miniaturized devices without mechanical parts, maintaining efficiency despite reduced dimensions.
Implementation Method 1
a first liquid LM more wetting than a second liquid LNM... the first liquid forming a film coming from a drop of first liquid LM supplied by the visco-inertial flowing and separated from the second liquid LNM
Implementation Method 2
a film of first liquid having displaced along the opposite orientation to said first gradient, the film being located between the drops of second liquid and the conduit
Implementation Method 3
applying a first pressure gradient along the conduit so as to generate a visco-inertial flowing... applying a second pressure gradient along the conduit, in the opposite orientation to the first pressure gradient
Implementation Method 4
generate a visco-inertial flowing displacing a first volume of drop stream according to said first gradient
Implementation Method 5
generate a viscous-capillary flowing displacing a second volume of drop stream according to said second gradient
Implementation Method 6
The implementation of the steps a) to d) defines an oscillation period... The method according to the invention then aims to implement the following steps: a) applying a first pressure gradient... c) applying a second pressure gradient... in the opposite orientation
Implementation Method 7
The liquid-liquid extraction is a method consisting of bringing two immiscible or poorly miscible liquid phases into contact with each other so as to allow a mass exchange of a component from one phase to the other
Data Source
AI summary
A method for counter-current liquid-liquid extraction in a sub-millimeter conduit is implemented from an initial liquid drop stream. The stream has alternating drops of a first liquid, and a second liquid less wetting than the first liquid and immiscible with the first liquid. One of the liquids includes a component to extract towards the other liquid. A first pressure gradient applied along the conduit generates a visco-inertial flow displacing a first drop stream volume according to the first gradient and generating a film of first liquid displaced along the opposite orientation, the film being located between the drops of second liquid and the conduit. The application of the first pressure gradient is stopped. A second pressure gradient is applied along the conduit, in the opposite orientation to generate a viscous-capillary flow displacing a second volume of according to the second gradient and application of the second pressure gradient stops.