Juan J. Parajó

New insight into the environmental impact of two imidazolium ionic liquids. Effects on seed germination and soil microbial activity

The next generation of ionic liquids must be synthetized taking into account structures that guarantee the suitable properties for a defined application as well as ecological data. Thus, searching of the right methodologies to know, quickly and efficiently, the ecological effects of these compounds is a preliminary task. The effects of two imidazolium based ionic liquids with different anions, 1-butyl-3-methylimidazolium tetrafluoroborate, [C4C1Im][BF4], and 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C3C1Im][NTf2], on seedling emergence of six tree species and on the microbial behaviour of two soils were determined in this work. Results showed that the highest doses of both ionic liquids caused the total inhibition of germination for almost all the species studied and that the seeds are more sensitive to the presence of these compounds than soil microbial activity. Nevertheless, signals of stress and death are observed from the results of heat released by microorganisms after the addition of the highest doses of both ionic liquids. The novelty of this work resides in the enlargement of knowledge of toxicity of ILs on complex organisms such as arboreal species and microbial activity of soils studied for the first time through a microcalorimetric technique.

SHORT-TERM THERMAL STABILITY OF IONIC LIQUIDS

It has been frequently said that onset temperatures obtained from dynamic thermogravimetric analysis can be used to estimate the short-term thermal stability of materials and also the relative thermal stability [1-3]. In this work the relative thermal stability was studied through dynamic analysis under the same experimental conditions for 50 Ionic Liquids (ILs). Several families with fixed anions and different cations and vice versa were chosen to have a comprehensive knowledge of thermal properties of ILs depending on the ions selection. Non-isothermal scans were performed under air atmosphere and a heating rate of 10 K · min-1 for all the selected ILs. It was observed that the anion influence on the thermal stability is stronger than the cation one, being ILs with [NTf2]- and [OTf]- anions the most stable; meanwhile dicyanamide, nitrate and acetate based ILs were the least stable.