Aspirin, which is used as a pain killer and is recommended to cure diseases like arthritis, was precipitated using gas-antisolvent (GAS) process. The objective of this study was to investigate the effects of four operating parameters, namely antisolvent addition, process temperature, solute concentration and the solvent type (methanol and acetone) on the final product particle size distribution, morphology and crystallinity. In accordance to particle size analysis and scanning electron microscopy (SEM), it was observed that the increment of antisolvent addition rate reduced the mean size of precipitated particles and the size distributions became narrower. Furthermore, the process temperature and the solute concentration had a reverse effect on the precipitated aspirin particle size. The crystallized particles had a mean size between 48-124 m. In contrast, particles precipitated from methanol solution had smaller mean size than from acetone. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that particles produced from acetone had more crystalline structure in comparison with the samples produced from methanol and also the unprocessed purchased aspirin. This can be explained through reduced involvement of methanol into the crystalline structure. The results proved the capability of GAS process for the production of aspirin for the therapeutic applications.

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