Supercritical CO2 Precipitation for Fine Particle Control
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Solution Overview
Problem
Existing methods for precipitating solutes from solutions often result in larger particle sizes and broader particle size distributions, with lower yields, limiting the production of fine drug and polymer microparticles or nanoparticles.
Innovation Solution
The method involves dissolving a substance in an organic solvent, adding an organic non-solvent to increase saturation, and then using a supercritical anti-solvent process, specifically with supercritical CO2, to precipitate the substance, employing techniques like GAS/SAS, PCA, ASES, or SEDS, to achieve rapid nucleation and smaller particle formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional solvent/non-solvent precipitation is used, then the process is simple and easy to operate, but the particle size is large and particle size distribution is broad
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional liquid precipitation to supercritical fluid precipitation. Specifically, it changes the physical state of the anti-solvent from liquid to supercritical fluid, and adjusts parameters such as pressure (7.38-30 MPa), temperature (304.1-354.1 K), and CO2 flow rate (10-1000 NL/h) to achieve precise control over particle size and distribution while maintaining process feasibility
Solution Approach 2:
The patent utilizes phase transitions of CO2 between supercritical and gaseous states. CO2 is maintained in a supercritical state during precipitation to achieve fine particle formation, then transitions to gaseous state for easy separation and product recovery. This phase transition mechanism enables both precise particle control and simplified product recovery
2Manufacturing precision
If supercritical anti-solvent process is used, then particle size is reduced and distribution is narrowed, but the process complexity increases
Solution Approach 1:
The patent employs parameter changes by optimizing pressure (7.38-30 MPa), temperature (304.1-354.1 K), solution concentration (0.1-5.0% wt/v), and CO2 flow rate (10-1000 NL/h) to achieve narrow particle size distribution. These controlled parameter variations enable precise particle engineering while managing process complexity through systematic optimization
Solution Approach 2:
The patent uses CO2 as an intermediary supercritical fluid that facilitates the precipitation process. CO2 acts as a mediator between the organic solvent and the precipitating environment, enabling controlled nucleation and growth. The intermediary role of CO2 simplifies the overall process by providing a single, controllable medium for particle formation
3Productivity
If higher saturation ratio is achieved by adding more non-solvent, then precipitation speed increases, but particle size may increase and yield decreases
Solution Approach 1:
The patent utilizes the phase transition of CO2 to supercritical state to achieve high saturation ratio without the drawbacks of excessive non-solvent addition. The supercritical state provides unique solvation properties that enable rapid precipitation while maintaining fine particle size control, resolving the contradiction between precipitation speed and particle size control
Solution Approach 2:
The patent changes the physical state and density parameters of the anti-solvent by using supercritical CO2. This parameter change allows achieving high supersaturation ratios that drive fast precipitation while the controllable density and solvation power of supercritical CO2 prevent particle agglomeration and maintain size control
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 produces fine particles with smaller sizes, narrower size distributions, and higher yields by controlling parameters such as solvent/non-solvent ratios, flow rates, and CO2 conditions, enhancing the precipitation process.
Implementation Method 1
CO2 is non-toxic, non-flammable, relatively inexpensive and recyclable gass. Its critical temperature and pressure (Tc=31.1 deg-C, Pc=7.38 MPa) are relatively mild. Supercritical CO2—where CO2 is in a fluid state while also being at or above its critical temperature and pressure—has several desirable features such as low viscosity and high solvent power for most organic solvents.
Implementation Method 2
Precipitation is the formation of a solid in a solution during a chemical reaction. The solid is called the precipitate, and the liquid remaining above the solid is called the supernate. Solvent/non-solvent precipitation is a technique commonly employed to isolate a substance in solid form from a solution.
Implementation Method 3
This generates a higher super-saturation ratio of the solution resulting in fast nucleation and growth.
Data Source
AI summary
A solute is precipitated from a solution of a solute, a solvent, and a non-solvent by preparing the solution and introducing the solution into a precipitation chamber contain a supercritical fluid.