Thermal conductivities of nine different bis­((trifluoromethyl)­sulfonyl)­imide-based ionic liquids (ILs), [C2mim]­[NTf2], [C4mmim]­[NTf2], [C8mim]­[NTf2], [P1,4,4,4]­[NTf2], [N1,1,1,4]­[NTf2], [N1,8,8,8]­[NTf2], [C4 3mpy]­[NTf2], [C4 4mpy]­[NTf2], and [C4mpy]­[NTf2], have been measured using the modified transient plane source method (MTPS) over the temperature range from 298 to 348 K at atmospheric pressure. The thermal conductivities of all the studied ILs are in the range of 0.120–0.150 W·m–1·K–1, with a combined expanded uncertainty of 0.01 W·m–1·K–1 at a 95% confidence level. In all cases, thermal conductivity decreases with increasing temperature and follows a linear trend, as is typical for most liquids and falls within the reported range for ILs. Two existing group contribution models (GCMs) with differing modeling philosophies have also been extended and tested against a database consisting of this new data combined with all existing IL thermal conductivity data in the literature. The extended GCMs yielded average absolute relative deviations of 5.5% and 4.9%, respectively, for the entire dataset.

Produced water (PW) generated from the petroleum industry, during the extraction of oil and gas, has harmful impacts on human health and aquatic life, due to its complex nature. Therefore, it is necessary to treat it before discharging it into the environment in order to avoid serious environmental concerns. In this research, oil adsorption from PW was investigated using clay-alginate beads loaded with ionic liquids (ILs), as the adsorbent material. The effects of several process parameters, such as the initial concentration of oil, contact time, pH, and temperature on the removal efficiency of the beads, were analyzed and optimized. Different characterization methods, such as the Fourier transform infrared spectrophotometer (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and thermal gravimetric analysis (TGA), were used to investigate the surface morphology, the chemical bond structure and functional group, and the thermal stability of the ILs-based beads. The results revealed that the clay-alginate-ILs beads indicated a removal efficiency of 71.8% at the optimum conditions (600 ppm initial oil concentration, 70 min contact time, 10 pH, and at room temperature) with an adsorption capacity of 431 mg/g. The FTIR analysis confirmed the successful chemical bond interaction of the oil with the beads. The SEM analysis verified that the beads have a porous and rough surface, which is appropriate for the adsorption of oil onto the bead’s surface. The TGA analysis provides the thermal degradation profile for the clay-alginate-ILs. The beads used in the adsorption process were regenerated and used for up to four cycles.

Produced water contaminated with oil has adverse effects on human health and aquatic life. Providing an efficient method for the removal of oil from produced water is a challenging task. In this study, the effects of carbon chain length and the cation nature of ionic liquids (ILs) on the removal efficiency of oil from produced water were investigated. For this purpose, seven ILs containing the bis (trifluoromethylsulfonyl) imide (NTf2) anion, and various cations such as imidazolium, pyridinium, phosphonium, and ammonium, were employed for the removal of oil from produced water via liquid–liquid extraction. The effects of process parameters such as the initial concentration of oil in produced water, contact time, pH, salinity, phase ratio, and temperature on the removal efficiency of oil were studied and optimized. 1-Decyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([C10mim][NTf2]) (IL4) was found to give the highest oil extraction efficiency of 92.8% under optimum conditions. The extraction efficiency was found to increase with increasing cation alkyl chain length from C2 to C10. The extraction efficiency of ILs based on cations follows the order imidazolium > ammonium > phosphonium > anpyridinium. Fourier Transform infrared spectroscopy (FTIR) was used to explore the ILs interaction with oil using [C10mim][NTf2] as a model. In addition, 1H and 13C NMR spectra were recorded to obtain a better understanding of the molecular structure of IL and to investigate the peak shifts in H and C atoms. Moreover, the cell viability of the most efficient IL, [C10mim][NTf2], in human cells was investigated. It has been concluded that this IL exhibited minimal cytotoxic effects at lower concentrations against human cell lines and is effective for the extraction of oil from aqueous media.