Heavy Elements in Ionic Liquids

Abstract

Heavy elements have in the recent past been studied extensively in the context of ionic liquids (ILs). This is because ILs have initially been thought of as "solve-it-all" problem solvers, from catalysis, to extraction, and inorganic and electrochemistry. In due course, it has been shown that ILs are indeed very versatile solvents and reaction media. As a consequence, many elements have been dissolved in ILs and their properties have been studied in IL solution. The current chapter focuses on the use of ILs for inorganic chemistry, in particular on what heavy elements have been studied in ILs, their properties and applications.

Ionic liquid-assisted formation of cellulose/calcium phosphate hybrid materials

“…TGA of the neat cellulose finds a weight loss of 96.1%, indicating that even the neat cellulose contains some fraction of non-volatile components. Overall the TGA curve is consistent with earlier data [65] on cellulose decomposition, where a first weight loss of ca. 4.5% is assigned to water desorption below ca.…”

“…Indeed, citrate has been suggested as a strong growth modifier for calcium phosphate from aqueous solution [76]. In contrast, the heterogeneity of the samples obtained with NaOH could be due to solubility issues of NaOH in the IL; as ILs are known to only poorly solubilize alkali halides [65]. A similar argument may apply to the case here.…”

“…Although XRD does not show any indication of NaCl, we have previously observed the formation of minor NaCl fraction in a different system [70]. The formation of NaCl could thus also be possible here, especially because alkali salts are generally poorly soluble in ILs [65]. The low fraction of sodium and chlorine observed in the EDXS data could be due to the fact that the precipitates were washed with water after synthesis and most NaCl would thus have been washed out.…”

“…ILs are nowadays (after an initial phase, where this aspect was completely ignored) regarded as moderately toxic. This is mostly due to the fact that (i) many ILs either have long alkyl tails on the cation or that (ii) some of the anions such as PF 6 − can degrade and form, among others, hydrofluoric acid, which is toxic [65–66]. In spite of this, the current data show that the extraction process used for sample purification is suitable to produce materials free of IL: neither EA (Table 5) nor EDXS (which is less sensitive, Table 2 and Table 4) detected any nitrogen in the current samples.…”

Controlled Synthesis of Polyions of Heavy Main-Group Elements in Ionic Liquids

“…Recently, several comprehensive reviews on syntheses of inorganic compounds in ILs have been published by Taubert [52], Feldmann [28], Dehnen [51], Janiak [42,53], Scrosati and Passerini [48], Morris [54], Mudring [55], Prechtl [56], Zhu [57], Dai [58], and Ruck [23,27,59] among others.…”