Simple models for supercritical extraction of natural matter

• We propose two simple models for supercritical fluid extraction of natural matter, based on the BET theory of adsorption.
• The proposed models have two and three parameters, respectively, which have clear physical meaning.
• The performance of the proposed models is similar and in some cases better than that of more rigorous models.

Based on the Brunauer–Emmett–Teller (BET) theory of adsorption, two mathematical models for correlating supercritical extraction data were developed. Each one of the models expresses the extraction yield as a function of time through one simple equation, which contains only three or two adjustable parameters, respectively, each one with a clear physical meaning. A comparison of the performance of the new models with those of Sovová’s and VT-II models shows that the first proposed model, with three adjustable parameters, produces in many cases an average deviation that is similar to that produced by the Sovová’s model, and is lower than that by the VT-II model, a remarkable result given the simplicity of the model. In addition, the second proposed model, which only has two adjustable parameters, performs well as compared to the rigorous models especially in the first period of the extraction and can be useful for generating first estimates of the parameters for data correlation with the first model. These results indicate that the proposed models are simple, useful and quick tools for correlating experimental data on supercritical extraction of natural matters.

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