Fabrication of chitosan particles through a coaxial nozzle under pressurized carbon dioxide

The generation of chitosan particles through supercritical carbon dioxide (SCCO₂) antisolvent process was studied. The experiments were carried out at temperatures of 60–100°C and pressures of 15–25 MPa with a 15 ml min⁻¹ CO₂ flow rate. As a feed solution, chitosan powder was dissolved in acetic acid:water:ethanol. Scanning electron microscopy (SEM) observations described that the precipitated chitosan products have irregular morphologies with the spherical, the spherical with fiber-like, and the fiber-like free-spherical particles. Interestingly, hollow-core chitosan particles generated when SCCO₂ antisolvent treatments were performed at a temperature of 60°C and pressures of 20–25 MPa. The Fourier transform infrared spectroscopy (FT-IR) spectra indicated that the structural properties of chitosan did not shift after the SCCO₂ antisolvent treatment. The results exhibited that this SCCO₂ antisolvent technique is likely to be fruitful for the generation of biopolymer particles with hollow-core structures.