Phosphonium ionic liquids in extraction techniques

Ionic liquids (ILs), also known as molten salts or fused salts, are a unique class of non-volatile and low-melting solvents which are composed entirely of cations and anions. These salts are liquid at room-temperature or below 100°C, thus the term 'room-temperature ionic liquids' (RTIL). Ionic liquids are known to possess some very intriguing properties such as negligible vapour pressure, remarkable thermal and electrochemical stability, non-flammability and high ionic conductivity. They have notable feature of tunability, due to which they are commonly known as 'designer solvents'. Interest in the different aspects and application of ILs in diverse fields has increased rapidly in the past few years which is pretty evident from the increasing number of research publications. The main aim of this thesis is to study the applicability of phosphonium-based ionic liquids in the field of analytical chemistry, focusing on extraction techniques. In this work, novel phosphonium-based ILs are synthesized by maintaining a common phosphonium-based cation and varying the counter-anion with carboxylate ones. Furthermore, these prepared ILs were tested for their critical micelle concentrations by using capillary electrophoresis as the mode of determination. In this work, different prospects of the use of phosphonium ILs in traditional as well as modern extraction techniques have been studied. This sub-set of ionic liquids has been the favourite choice of researchers in liquid-liquid extraction as a co-solvent as replacements of traditional volatile organic solvents. Similarly, in various microextraction techniques, phosphonium ionic liquids have been favored as a co-solvent or an ion-pair reagent while in the membrane extraction processes, they have been used as carrier in the transport of metal ions. Moreover, different parameters affecting the extraction process, for example, the effect of alkyl chain length of the ionic liquid cation and anion, branching, or even the effect of temperature have been studied. Phosphonium based ionic liquids not only find their place in the extraction of metal ions, phenolic compounds and radiochemical elements. ILs with desirable properties can be obtained by playing with the design of cation and anion of a particular IL. Taking advantage of this unique feature, many researchers have synthesized ILs to test their applicability in the extraction methods with remarkable extraction efficiencies. In the experimental section of this work, the critical micelle concentration of the synthesized phosphonium based ILs has been determined by using CE. Also, the electrosmotic flow in the fused silica capillaries are measured with the synthesized ILs and the influence of the alkyl chain length on the same is determined. Such ILs have great potential as novel capillary coatings for CE

Effect of Ionic Liquids on Zebrafish (<i>Danio rerio</i>) Viability, Behavior, and Histology; Correlation between Toxicity and Ionic Liquid Aggregation

The effect of 11 common amidinium, imidazolium, and phosphonium based ionic liquids (ILs) on zebrafish (<i>Danio rerio</i>) and Chinese hamster ovary cells (CHO) was investigated with specific emphasis on the effect of anion and cation chain length and aggregation of phosphonium based ILs. Viability and behavioral alteration in the locomotor activity and place preference, after IL treatment of 5 days postfertilization larvae, was recorded. Behavior and histological damage evaluation was performed for adult fish in order to get insight into the long-term effects of two potential biomass-dissolving ILs, [DBNH]­[OAc] and [P₄₄₄₁]­[OAc]. To get an understanding of how IL aggregation is linked to the toxicity of ILs, median effective concentrations (EC₅₀) and critical micelle concentrations (CMC) were determined. The long-chain ILs were significantly more toxic than the short-chain ones, and the anion chain length was shown to be less significant than the cation chain length when assessing the impact of ILs on the viability of the organisms. Furthermore, most of the ILs were as monomers when the EC₅₀ was reached. In addition, the ILs used in the long-term tests showed no significant effect on the zebrafish behavior, breeding, or histology, within the used concentration range