Valorization of wild thyme (Thymus serpyllum L.) herbal dust by supercritical fluid extraction – Experiments and modeling

The aim of this study was to develop five empirical and three mass-transfer based models for fitting the T. serpyllum SFE process. Additionally, the determination of the effect of SFE parameters (pressure, temperature, CO₂ flow rate and mean particle size) on kinetic curves and model parameters was investigated. Among the selected models, all empirical and mass-transfer models provided adequate fit with experimental data. However, mass-transfer model VIII has proved to fit the experimental results accordingly and has shown that the most influential parameters were pressure and CO₂ flow rate. The pressure and CO₂ flow rate exhibited positive effect, while the temperature had rather negative impact on Y. In addition, the initial slopes of Model VIII were calculated in order to increase the efficiency and reduce unnecessary process costs.