Natural carotene is micronized by the SEDS process through prefilming atomization (SEDS-PA) with the aim of evaluating the efficiency of prefilming atomization, examining the variation of carotene purity induced by the SEDS-PA process and studying the influence of operating variables on the particle size (PS) of the carotene precipitates. The carotene/dichloromethane solution to be atomized is driven through a liquid distributor with spiral slots in the prefilming atomizer as a thin film swirling at 45°. At the exit of the atomizer, the atomizing supercritical CO 2 (SC-CO 2 ) stream impinges on the film at 45°. Through the impingement and the use of swirling, the annular solution film is disintegrated into fine drops, and the mixing of the SC-CO 2 and solution is intensified. Compared to the process in which solution is driven through the inner capillary of the atomizer while SC-CO 2 is driven through its annular passage, the SEDS-PA process can obtain smaller droplets and finer microparticles with a narrower particle size distribution (PSD). After micronization by the SEDS-PA process, the purity of carotene microparticles is increased for unprocessed carotene with purity ranging from 30% to 87%, but it decreased for carotene with purity higher than 87%. The CO 2 flow rate, solution flow rate, solution concentration, and pressure have marked influences on the particle size (PS), and the PSD broadens with increasing PS. Mechanisms that control PS are explained in terms of liquid atomization, agglomeration of particles, volumetric expansion of solution in SC-CO 2 , and nucleation and growth processes of particles. The dependence of the PS on temperature is not clear from all of the experiments performed.

Application of micronizing technologies in processing Chinese herbal medicines is very important to improve the forms of prepared Chinese herbal medicines and promote their therapeutic efficacy. Baicalin, a major active component of the typical Chinese herb medicine Scullateria baicallensis Georgi, was micronized using the Solution Enhanced Dispersion by Supercritical fluids though Prefilming Atomization (SEDS-PA) process with the aim of evaluating the efficiency of applying supercritical fluid precipitation technologies in Chinese herb medicine. This study has shown that acicula or rod-like baicalin crystals with Particle Size (PS) of about 20×100 µm were successfully micronized by the SEDS-PA process to long rod-like, twisted fiber-like or fibrous net-like microparticles with PS of 0.1-2.2 µm in width within the range of experiments performed. It was found that a substantial reduction of baicalin microparticles' sizes could lead to a marked increase of adhesions among them and subsequent microparticles agglomeration. With the increase of supercritical CO 2 flow rate and the decrease of solution concentration and solution flow rate, smaller and much more agglomerated microparticles were obtained. Increasing pressure led to formation of smaller microparticles. A larger tendency of particles agglomeration was produced at a higher temperature.

Micronized Coenzyme Q10 (CoQ10) is prepared with a rapid expansion of supercritical solution (RESS) process, which does not employ toxic organic solvent. Four factors, namely extraction pressure, extraction temperature, nozzle diameter and precipitation temperature are optimized by a four-level orthogonal array design. The optimum micronization conditions are determined as follows: extraction pressure 25 Mpa, extraction temperature 40°C, nozzle diameter 200 μm, and precipitation temperature 25°C. Under the optimum conditions, micronized CoQ10 with a MPS of 147.9±27.3 nm is obtained. The micronized CoQ10 obtained was characterized by High performance liquid chromatography-mass spectrometry (LC–MS) and High performance liquid chromatography (HPLC) analyses. The results showed that RESS micronization process does not induce degradation of CoQ10 and the obtained CoQ10 particles have higher dissolution rate and solubility compared with unprocessed CoQ10 powder.

Nanoscale lignin was successfully prepared with a supercritical antisolvent (SAS) apparatus using acetone as a solvent and superciritical carbon dioxide as an antisolvent. Four factors were studied and optimized by a four-level orthogonal array design (OAD). According to analysis of variance, precipitation pressure had a significant effect on mean particle size. The optimal conditions are as follows: precipitation temperature 35 °C, precipitation pressure 30 MPa, temperature difference +10 °C and concentration of lignin solution 0.5 mg/mL. The micronized lignin under the optimal conditions was characterized by Scanning Electron Microscopy (SEM), Fourier-transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS) and X-Ray Diffraction (XRD) analyses. The results showed the mean particle size of micronized lignin was 0.144 ± 0.03 μm and had no degradation. The solubility of micronized lignin was improved significantly in distilled water.