In this study, the extractive desulfurization of model fuel oil with ionic liquids (ILs) has been studied in an attempt to gain insights into the dominant forces controlling the extraction efficiencies of aromatic sulfur compounds, thiophene and dibenzothiophene. This work investigates the intrinsic properties of a series of common ILs based on a constant (molar) amount of IL to directly draw insights into the intrinsic properties of each IL’s extraction capability. Experimentally both the cation and anion size influenced the efficiency of extraction, following the trend pyridinium > imidazolium > pyrrolidinium for the cation and [NTf2]− > [OTf]− > [PF6]− > [BF4]− for the anion. Similar trends are observed for both thiophene and dibenzothiophene. Density functional theory modeling, using the APFD method, was employed to quantify the complexation energies and corresponding dispersion contributions between thiophene and the cations as well as between thiophene and the anions used in this work, showing a similar trend to the experimental results. Through a combination of experimental and computational analyses it is suggested that the dominant force in extraction is dispersion-driven binding between the ions and S-compounds.

Ionic Liquids (ILs) have been suggested as useful extractants of aromatic nitrogencontaining compounds (N-compounds) from fuel oils. In this systematic study, ILs based on common cations and anions are employed as extractants of the archetypical N-compounds pyridine and indole from a model oil consisting of decane and toluene. The performance of these ILs as extractants of N-compounds is compared and rationalized. It is demonstrated that the cation and anion sizes (offering more surface area for extractants to interact) are the major factors determining the effectiveness of N-compounds extraction, although hydrogen bond donor/acceptor abilities of ILs can also play a role in the removal of these N-compounds. In this study, some ILs are found to dissolve considerable amount of oil contents. This undesired property can be controlled by the size of IL ions

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The reversible electrodeposition of zinc was investigated in an aqueous electrolyte containing zinc bromide (50 mM) and 1-ethylpyridinium bromide ([C2Py]Br, 50 mM) by cyclic voltammetry, chronoamperometry, and scanning electron microscopy. Unusual voltammetric behaviour for the Zn/ZnII redox couple was observed in the presence of [C2Py]Br. Passivation of the redox couple was observed after a single deposition–stripping cycle at switching potentials more negative than −1.25 V versus Ag/AgCl. This unusual behaviour was attributed to the reduction of 1-ethylpyridinium cations to pyridyl radicals and their follow-up reactions, which influenced the zinc electrochemistry. This behaviour was further seen to modify the nucleation process of electrodeposition, which altered the morphology of zinc electrodeposits.

The suitability of N-ethylpyridinium bromide as a potential electrolyte additive for zinc electrodeposition in aqueous solution has been investigated by a combination of cyclic voltammetry, bulk electrolysis, scanning electron microscopy, synthesis and NMR spectroscopy. The current magnitudes of the Zn/Zn(II) redox reaction observed at the electrode decreased dramatically after a single deposition/stripping cycle in the presence of N-ethylpyridinium bromide at switching potentials more negative than −1.30 V vs Ag/AgCl. This is attributed to the reduction of the N-ethylpyridinium cation to form a pyridyl radical that subsequently and rapidly dimerizes. The proposed dimer was synthesized and shown to have a low solubility in aqueous solutions, consistent with a passivation of the electrode surface by precipitation and inhibition of redox behavior. Based on this understanding for the pyridinium cation reduction, alternative pyridinium-based additives have been examined in order to determine their influence on zinc electrodeposition.