Supercritical Fluid Assisted Particle Synthesis Antoinette Kretsch New Jersey Institute of Technology

Supercritical Fluid Extraction Solvent enters system Supercritical CO 2 Collection trap Exiting CO 2 and solvent Left over particles

Analysis Techniques Beckman Coulter N4 Plus: Submicron Particle Size Analyzer –determines particle size by measuring the rate of change in laser light intensity scattered by particles as they diffuse through a fluid Leo 1530 VP: SEM Microscope –Produces 3-D image magnified x100,000 by spraying specimen with fine metal coating and sending beam of electrons over the surface to be projected onto fluorescent screen SigmaScan: Systat software program –Collects data such as diameter and area of nanoparticles using pictures taken by the SEM FTIR: Fourier Transform Infrared Spectroscopy –Used to identify chemical bonds in various substances by interpreting the infrared absorption spectra

Conclusions A smaller nozzle will yield smaller, less agglomerated particles A pressure closer to supercritical pressure (78 bar for CO 2 ) will yield smaller particles, so 82 bar had smaller particles than 100 bar The higher ratio of acetone to DCM will yield smaller particles with a narrow size distribution although the particles will have a distorted shape

Suggestions for Further Study Can a stronger pump be used for force the solution through tinier micronozzles (ex: 10 μm and 5 μm)? Is there a better way to increase yield of particles (particles stick to sides of, top of, and apparatus inside the collecting chamber and are hard to remove) and decrease amount lost to air? What would the results be if another supercritical fluid was used instead of CO2? Can the durability of the micronozzles be increased so they last more than one or two trials?