Enhanced extraction of phenol from model oils using ionic liquids elucidated with neutron diffraction

Abstract

Aromatic cation ionic liquids (ILs) based on alkylpyridiniums are shown to be good phenol extractants from model oils (hexane/toluene).

The structure of protic ionic liquids based on sulfuric acid, doped with excess of sulfuric acid or with water

“…70 Similar features are observed in aprotic ILs containing N-alkylpyridinium cations, arising from anions associating equatorially around pyridinium cations. 71,72,73 In contrast to typical ionic liquid structure, there is very close anion-anion interaction in both PILs. The corresponding {SO4}-{SO4} associations (Figure 3, top, blue dashed and solid curves) closely resemble sulfate associations in 'neat' sulfuric acid (first shell at 4.6 Å, second one at 6.6-11 Å).…”

Phenol Recovery from Aromatic Solvents by Formation of Eutectic Liquids with Trialkyl-2,3-dihydroxypropylammonium Chloride Salts

“…where [phenol] init and [phenol] f inal are, respectively, the initial and post extraction concentrations of phenol determined in the model oil phase. The results and a comparison with the data that were obtained for representative tetraalkylammonium chlorides (from Turner et al [29]) and from choline chloride are shown in Table 3. All of the salts tested showed good extraction of phenol from hexane, with greater than 87% removal while using 1 and 2.…”

“…Examining data from the screening of extraction with a broad range of tetraalkylammonium halide salts ([NR 4 ]X, R = Me, Et, Pr, Bu, and X = Cl, Br, I) [29] and comparison with the literature, some clear trends in the impact of the different eutectic forming organic salts on phenol extraction are apparent. There is a need for a hard, basic anion (supporting phenol-OH hydrogen bond donation to the anion as a primary association mode [30,36]), and the extraction efficiency increases, in general, with increasing size of the N-alkyl substituents from Me-Bu, as seen for the [NR 4 ]I salts, where phenol extraction from hexane increased from 7% to 96%.…”

“…Studies of eutectic mixtures of phenol with aromatic ionic liquid salts using neutron scattering [29,30] identified the solvation of phenol molecules by both the cation and anion components of the salt, and that phenol extraction is enhanced when more weakly coordinating anions are used. This has been interpreted as a consequence of a reduction in the strength of cation-anion association, allowing for increasingly favourable cation-phenol interactions to facilitate improved extraction.…”

Ionic liquid-assisted synthesis of mesoporous polymers and carbon materials: the self-assembly mechanism

“…The results above also provide explanations on why phenolic compounds with different hydroxyl groups present different extraction efficiencies during extraction from waste water by employing imidazolium-based ILs. [48][49][50] The extraction percentage for phenol generally exceeds 90%, while that for resorcinol is smaller than 60%. 48 Phenol resides mostly in the hydrophobic phase of the IL cation, but its H-bonding ability via -OH results in a small ratio of phenol remaining in the aqueous phase.…”