Evaluation of the conductor-like screening model for real solvents for the prediction of the water activity coefficient at infinite dilution in ionic liquids

Ionic liquids (ILs) have attracted great attention, from both industry and academia, as alternative fluids for very different types of applications. The large number of cations and anions allow a wide range of physical and chemical characteristics to be designed. However, the exhaustive measurement of all these systems is impractical, thus requiring the use of a predictive model for their study. In this work, the predictive capability of the conductor-like screening model for real solvents (COSMO-RS), a model based on unimolecular quantum chemistry calculations, was evaluated for the prediction water activity coefficient at infinite dilution, gamma(infinity)(w), in several classes of ILs. A critical evaluation of the experimental and predicted data using COSMO-RS was carried out. The global average relative deviation was found to be 27.2%, indicating that the model presents a satisfactory prediction ability to estimate gamma(infinity)(w) in a broad range of ILs. The results also showed that the basicity of the ILs anions plays an important role in their interaction with water, and it considerably determines the enthalpic behavior of the binary mixtures composed by Its and water. Concerning the cation effect, it is possible to state that generally gamma(infinity)(w) increases with the cation size, but it is shown that the cation-anion interaction strength is also important and is strongly correlated to the anion ability to interact with water. The results here reported are relevant in the understanding of ILs-water interactions and the impact of the various structural features of its on the gamma(infinity)(w) as these allow the development of guidelines for the choice of the most suitable lLs with enhanced interaction with water.

Extended use of gamma irradiation in wild mushrooms conservation: validation of 2 kGy dose to preserve their chemical characteristics

Irradiation is recognized by international organizations as a conservation technology, and its application to wild mushrooms has been tested in some species. Our research group evaluated the effectiveness of gamma irradiation to conserve different samples of highly appreciated species, particularly, Lactarius deliciosus, Macrolepiota procera, Boletus edulis and Hydnum repandum. From those results and considering also international recommendations on this subject, the 2 kGy dose was chosen for further studies. Therefore, the application of gamma irradiation at 2 kGy dose was extended to Boletus pinophilus Pilát & Dermek and Clitocybe subconnexa Murrill to validate the proposed technology. Considering the obtained results, some of the analysed chemical parameters (specially sugars and fatty acids), as well as the antioxidant activity, showed significant changes after irradiation treatment, particularly in B. pinophillus, probably due to its higher water content. Nevertheless, the obtained differences did not seem to be sufficient to change the organoleptic characteristics of these mushrooms. Furthermore, the antioxidant activity was generally higher in irradiated samples. In conclusion, the detected chemical changes might be considered as acceptable, when considering the high advantages of gamma irradiation at decontamination and/or disinfestation level.