Nanoparticle Production via Supercritical Fluid Phase Transition
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Solution Overview
Problem
Current methods for producing nanoparticles, such as RESS and SAS, face challenges in efficient recovery and continuous processing due to large volume expansion and agglomeration, leading to varying particle sizes and extensive filtering requirements.
Innovation Solution
A process involving the dissolution of a solute in a supercritical fluid, followed by rapid cooling to solidify the fluid and prevent particle growth, allowing the solidified fluid to sublime, thereby simplifying nanoparticle collection and enabling continuous operation without filtration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rapid expansion of supercritical solution is used to produce nanoparticles, then particle formation is achieved, but large volume expansion occurs requiring extensive filtering and recovery
Solution Approach 1:
The patent utilizes phase transitions of the supercritical fluid (scCO2) from supercritical state to gaseous state through pressure reduction, enabling particle formation and subsequent easy separation. The scCO2 expands and transitions to gas phase, carrying particles that can be collected by pressure differential without complex filtration
Solution Approach 2:
The patent extracts the supercritical fluid (CO2) from the particle production process by allowing it to expand and transition to gaseous state, separating it from the nanoparticles. This extraction of the fluid phase enables direct particle collection without extensive filtering or recovery systems
2Manufacturing precision
If high expansion ratios are used to produce very small particles, then nanoparticle size is reduced, but particle concentration in expanded gas becomes very low reducing recovery efficiency
Solution Approach 1:
The patent employs pneumatic principles by utilizing the expanding supercritical fluid gas to carry and transport nanoparticles directly to collection surfaces. The gas flow dynamics enable particle deposition on cooled surfaces or in collection chambers, maintaining high recovery efficiency even at high expansion ratios
Solution Approach 2:
The phase transition of scCO2 to gaseous state creates a carrier gas that transports nanoparticles efficiently. The gas phase allows for high expansion ratios while maintaining particle concentration through controlled expansion and directed flow to collection surfaces
3Manufacturing precision
If batch processing is used to handle filtering requirements, then particle separation is achieved, but continuous production capability is lost
Solution Approach 1:
The patent enables continuous particle production by eliminating the batch filtering step. The expanded scCO2 gas carrying nanoparticles flows continuously through the system, with particles being deposited on cooled surfaces or collected in continuous flow chambers, allowing uninterrupted production
Solution Approach 2:
By extracting the need for filtration through phase transition-based separation, the process becomes continuous. The scCO2 gas naturally separates from particles through expansion and cooling, allowing continuous particle production without batch processing interruptions
4Ease of operation
If fixed volume expansion is used for particle recovery, then particle collection is simplified, but particle size variation increases requiring filtering
Solution Approach 1:
The patent employs dynamic control of expansion conditions, allowing the system to adjust expansion ratios and cooling rates to optimize particle size uniformity. The dynamic interaction between expanding gas, cooling surfaces, and particle formation enables controlled particle growth while maintaining collection simplicity
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 process effectively produces and harvests nanoparticles in a smaller area, preventing agglomeration and allowing for continuous production with reduced particle size variability and no need for secondary recovery vessels or filters.
Implementation Method 1
dissolves a solute in a supercritical fluid
Implementation Method 2
rapidly expands the dissolved solute to form nanoparticles
Implementation Method 3
rapid drop in pressure, which results in supersaturation of the solute and a precipitation of solid particles
Implementation Method 4
rapidly cools the expanding fluid and particles to a temperature below the temperature at which the fluid, e.g., scCO2, solidifies
Implementation Method 5
the CO2 and the solute are cooled to a temperature below that at which CO2 solidifies, e.g., below −80° C., so the CO2 freezes
Implementation Method 6
allows the solidified fluid to sublimate or evaporate into a gas, thus leaving behind the produced nanoparticles
Implementation Method 7
allows the solidified fluid to sublimate or evaporate into a gas
Data Source
AI summary
A process for producing nanoparticles of a substance, including in a first chamber, forming a dispersion of a substance in a fluid and bringing the fluid into a supercritical state; passing the dispersion from the first chamber through a cooling device or into a cooling zone in a second chamber, wherein the cooling device or cooling zone configured to reduce temperature of the dispersion below a temperature at which the fluid forms solid particles such that nanoparticles of the substance are formed, wherein the second chamber comprises a surface configured to receive the solid particles of the fluid and the nanoparticles of the substance; allowing pressure to decrease and/or temperature to increase in the second chamber to transform the solid particles into a gaseous state, removing the fluid in the gaseous state and with the nanoparticles remaining on the surface; and collecting the nanoparticles from the surface.