Using Kinetics Results of Esterification with Citric Acid to Determine the Nature of the Porosity Structure of the Different Parts of the <i>Nymphaea nouchali</i>

In this study, the <i>Nymphaea nouchali</i> aquatic plant was subdivided into 12 parts. To extract the bioactive organic molecules, present in these different parts of the <i>Nymphaea nouchali</i> aquatic plant, the esterification method with citric acid was used. The aim of this study was to determine the nature of the porous structure of each part, either microporous structure or mesoporous and macroporous structure, from the results of their kinetic constants during esterification with citric acid, their water content and their density. In this way, kinetic monitoring was carried out for each part of the plant, enabling the different kinetic constants of each esterification to be determined. In addition, the water content and density of each part of the <i>Nymphaea nouchali</i> aquatic plant were determined. This water content of each part of the <i>Nymphaea nouchali</i> can already give an idea of the nature of their pore structure. But by comparing the water content with the kinetic constants of each part, in particular, the partial order with respect to citric acid and the partial order with respect to organic molecules and the initial and long-term conversion, it is now possible to define the nature of their porous structure. But with a third comparison of the kinetic data and water content with the density of each part of the <i>Nymphaea nouchali</i>, the nature of the porous structure of each part becomes increasingly clear and precise. The maximum fatty acid extraction yield is assigned to the part with a mesoporous-macroporous structure. However, it had been noted that the microporous structure parts also show high fatty acid extraction yields, and by determining the extraction yields per gram of sample, it is clear that those of the microporous structure parts are very high. These results confirm that, by virtue of their filiform nature and small molecular widths, these fatty acid molecules manage to locate themselves preferentially in the microporous structure parts.