Thiols׳ extraction from “jet-fuel” assisted by ionic liquids in hollow fibre membrane contactors

Interphase Surface Stability in Liquid-Liquid Membrane Contactors Based on Track-Etched Membranes

A promising solution for the implementation of extraction processes is liquid–liquid membrane contactors. The transfer of the target component from one immiscible liquid to another is carried out inside membrane pores. For the first time, highly asymmetric track-etched membranes made of polyethylene terephthalate (PET) of the same thickness but with different pore diameters (12.5–19 nm on one side and hundreds of nanometers on the other side) were studied in the liquid–liquid membrane contactor. For analysis of the liquid–liquid interface stability, two systems widely diverging in the interfacial tension value were used: water–pentanol and water–hexadecane. The interface stability was investigated depending on the following process parameters: the porous structure, the location of the asymmetric membrane in the contactor, the velocities of liquids, and the pressure drop between them. It was shown that the stability of the interface increases with decreasing pore size. Furthermore, it is preferable to supply the aqueous phase from the side of the asymmetric membrane with the larger pore size. The asymmetry of the porous structure of the membrane makes it possible to increase the range of pressure drop values between the phases by at least two times (from 5 to 10 kPa), which does not lead to mutual dispersion of the liquids. The liquid–liquid contactor based on the asymmetric track-etched membranes allows for the extraction of impurities from the organic phase into the aqueous phase by using a 1% solution of acetone in hexadecane as an example.

Triphenyl methyl phosphonium tosylate as an efficient phase transfer catalyst for ultrasound-assisted oxidative desulfurization of liquid fuel

The novel phosphonium-based ionic liquid (IL), triphenyl methyl phosphonium tosylate ([TPMP][Tos]), has been synthesized and applied as a phase transfer catalyst (PTC) in the ultrasound-assisted oxidative desulfurization (UAODS). Oxidation of model fuel (MF) containing dibenzothiophene (DBT) was carried out using an equimolar mixture of H₂O₂-CH₃COOH as an oxidant at 40-70 °C in the presence of IL. The sulfur compound is converted into polar sulfone, and the maximum desulfurization efficiency was examined. The effect of process parameters such as reaction temperature, reaction time, molar ratio of oxidant to sulfur (n(O/S)), and the mass ratio of ionic liquid to model fuel (m(IL/MF)) was studied, and the conditions for maximizing the DBT conversion rate were found. Maximum conversion (> 99%) was obtained at a temperature of 70 °C with m(IL/MF) of 0.8. The oxidation reactivity of various sulfur compounds was studied at different time intervals. To verify the effect of ionic liquid and ultrasound irradiation, extractive desulfurization (EDS), oxidative desulfurization (ODS), and UAODS in the presence of IL were carried out. The experimental results show that the UAODS process gives the highest desulfurization efficiency. A kinetic study was performed to estimate the rate constant and the order of oxidation reaction.

Transport of imidazolium-based ionic liquids with different anion/cation species in sand/soil columns

Ionic liquids (ILs) have been widely used as environmentally friendly solvents to replace volatile organic solvents in the chemistry industries. They have a high water solubility and potential risk to organisms in the soil-water environment. At present, most studies focused on the batch sorption of ILs in soil and neglected the investigation of IL transports in soil, which results in a lack of understanding of the structure-dependent mobility of ILs in the environment. Laboratory-scale sand/soil column experiments were performed to study the transport of imidazolium-based ILs, such as [C₄mim][OTF], [C₄mim][TOS], [C₄mim][MeSO₃], [C₄mim][BF₄], [C₂mim][BF₄], and [C₆mim][BF₄] including different counteranions and alkyl chain lengths of IL cations. Batch experiments were also carried out to compare the difference of sorption distribution coefficient (K_d) between the batch and column experiments. A one-dimensional convective-dispersive model using CXTFIT code was created based on the measured breakthrough curves (BTCs) to estimate the column transport parameters. For the anion, [BF₄^-], the K_d of ILs in both batch and column experiments increased with increasing alkyl chain lengths of the IL cation. In batch tests, counteranions showed no influence on the K_d of [C₄mim][OTF], [C₄mim][TOS], [C₄mim][MeSO₃], [C₄mim][BF₄], [C₂mim][BF₄], and [C₆mim][BF₄]. However, in column tests, the BTCs of 1-butyl-3-methylimidazolium-based ILs were anion dependent as evidenced by the change of retardation factor (R) for different counteranions. Furthermore, the effects of transport distance (11cm, 15cm, 19cm, and 24cm) on the mobility of ILs were estimated. The longer distances signified an increase in the contact time and more binding sites for ILs and therefore, the smoother shapes of BTCs in column experiments.