Novel thiosalicylate-based ionic liquids for heavy metal extractions

Abstract

This study aims to develop novel ammonium and phosphonium ionic liquids (ILs) with thiosalicylate (TS) derivatives as anions and evaluate their extracting efficiencies towards heavy metals in aqueous solutions. Six ILs were synthesized, characterized, and investigated for their extracting efficacies for cadmium, copper, and zinc. Liquid-liquid extractions of Cu, Zn, or Cd with ILs after 1-24h using model solutions (pH 7; 0.1M CaCl2) were assessed using flame atomic absorption spectroscopy (F-AAS). Phosphonium-based ILs trihexyltetradecylphosphonium 2-(propylthio)benzoate [P66614][PTB] and 2-(benzylthio)benzoate [P66614][BTB] showed best extraction efficiency for copper and cadmium, respectively and zinc was extracted to a high degree by [P66614][BTB] exclusively.

Novel 3-Hydroxy-2-Naphthoate-Based Task-Specific Ionic Liquids for an Efficient Extraction of Heavy Metals

“…The IL was obtained in a high yield (≥95%) after the washing steps. A low chloride content of 0.15 wt% was achieved (Table S1 ), which is in line with or significantly lower than the values of similarly synthesized TSILs from chlorinated precursors, with contents up to 6 wt% (Mikkola et al, 2006 ; Kogelnig et al, 2008 ; Stojanovic et al, 2010 ; Fischer et al, 2011 ; Leyma et al, 2016 ). The structure of the IL was analyzed by evaluating FT-IR, 1 H-NMR as well as MS spectra, confirming the desired constitution of the compound.…”

“…This reduces the possibilities for comparisons. Nevertheless, our data clearly demonstrate that 3-hydroxy-2-naphthoate as a highly hydrophobic anion does strongly reduce leaching compared to the works of Leyma and Platzer (Platzer et al, 2015 ; Leyma et al, 2016 ), who investigated ILs composed of similar cations but less hydrophobic anions.…”

“…Successful metal extraction has been achieved by introducing functional groups in cations as well as anions. These include urea-, thiourea-, or thioether-substituted alkyl groups on the alkyl chains of imidazoles (Visser et al, 2002 ) as well as (thio-)salicylate (Stojanovic et al, 2010 ; Leyma et al, 2016 ), maltolate (Platzer et al, 2015 ), or thioglycolate (Platzer et al, 2016 ) groups as part of the anion. By choosing additional properties, e.g., the length of the alkyl chains on the cation, TSILs may simultaneously act as hydrophobic solvents and extractants (Zhao et al, 2005 ).…”

Review on Application of Quaternary Ammonium Salts for Gas Hydrate Inhibition

“…Among their advantageous characteristics include having surface-active properties, bioactive, and possess anti-microbial activity [49,50]. Over the last decade, researchers have been investigating on this class of IL and found their improved chemical and thermal stability compared to imidazolium and pyridinium based ILs, their solvating properties and unique miscibility which can be utilized in specific applications [45,[51][52][53][54]. A typical QAS consists of a positively-charged nitrogen atom attached to four carbon atoms [55].…”

Phosphonium ionic liquids as extractants for recovery of ruthenium(III) from acidic aqueous solutions

“…Ionic liquids, such as phosphonium ILs, can be used as extractants for liquid–liquid extraction of organic compounds (Marták and Schlosser 2004, 2006, 2016), lanthanides (Kumari et al 2016), heavy metals (Guo et al 2011; Leyma et al 2016; Regel-Rosocka et al 2006, 2012; Vander Hoogerstraete et al 2013) or PGMs (Cieszynska and Wisniewski 2010, 2012; Papaiconomou et al 2015; Regel-Rosocka et al 2015; Rzelewska et al 2016). They are also applied as carriers of metal ions in polymer inclusion membranes (Baczyńska et al 2016; Baczyńska and Regel-Rosocka 2013; Kogelnig et al 2011; Pośpiech 2015; Regel-Rosocka et al 2012, 2015) or supported liquid membranes (Alguacil et al 2010; de San et al 2014) and in sorption as Cyphos-impregnated resins or biopolymer capsules (Guibal et al 2008; Navarro et al 2016; Vincent et al 2008).…”