Thermal Stability and Kinetic Study of Benzimidazolium Based Ionic Liquid

Phytotoxic responses of wheat to an imidazolium based ionic liquid in absence and presence of biochar

Research on ionic liquids (ILs) and biochars (BCs) is a novel site of scientific interest. An experiment was designed to assess the effect of 1-propanenitrile imidazolium trifluoro methane sulfonate ([C₂NIM][CF₃SO₃]) ionic liquid (IL) and IL-BC combination on the wheat plant. Three working standards of the IL; 50, 250, 500 and 1000 mg/L, prepared in deionized water, were tested in the absence and presence of BC on wheat seedling. Results indicated significant decrease ‏in seed germination (%), length, fresh weight, chlorophyll a, b and carotenoid contents of wheat ‏seedlings at 250, 500 and ‏1000 mg/L of the ‏IL. An admirable increase in phenolic and 2,2-diphenyl-1-picrylhydrazyl (DPPH) contents of wheat seedlings was noted at 250, 500 and ‏1000 mg/L of the IL. The application of BC significantly ‏ameliorated the negative effects of IL on the selected parameters of ‏wheat. It is inferred that the undesirable effects of the IL on wheat growth can be positively restored by addition of BC.

Hydrophobic ammonium based ionic liquids for efficient extraction of textile dyes from aqueous media: Extraction study and antibacterial evaluation

Alizarin red S (ARS) extraction from aqueous medium was carried out using hydrophobic ionic liquids (ILs) containing trioctylammonium cation paired with 4-tert-butylbenzoate ([TOA][Butbenz] (IL1), 4-phenylbutanoate ([TOA][PheBut] (IL2), 3-4-dimethylbenzoate ([TOA][DMbenz] (IL3), naphthoate, ([TOA][Naph]) (IL4), salicylate ([TOA][Sali]) (IL5) and nonanedioate ([TOA]2[Nona]) (IL6). The findings demonstrated that all of the tested ILs were efficient for extracting ARS, however, [TOA]2[Nona] was more effective than others. For the extraction of ARS from the aqueous phase, the effects of various parameters including the initial pH of the dye solution, contact time, ILs to dye volume ratio (VIL:VW), dye concentration, temperature, and salt effect were investigated. The spontaneity of the liquid-liquid extraction of ARS from the aqueous phase to the IL phase was confirmed by thermodynamic parameters. More than 90% of the ARS was extracted from the aqueous phase to the IL phase throughout all experiments. Interaction of selected IL with dyes were confirmed using FTIR analysis. The standard bacterial strains of Escherichia coli (E. coli) ATCC BAA-2471 (gram negative) and Methicillin-resistant Staphylococcus (MRSA) ATCC 43300 (gram positive) were used for evaluating antibacterial activity. The lower dose (250 ppm), the ILs1, 2, 3, 4, 5, and 6 inhibited 0.40, 1.50, 6.50, 1.50, 2.50, and 0.50 mm growth of E. coli, and 4.0, 2.0, 16.50, 0.40, 5.0, and 3.50 mm growth of MRSA, respectively. The experimental findings confirmed that the present ILs can be utilized as an effective solvent for ARS and other dyes extraction from aqueous media.

Improving performance of mesoporous MOF AlTp impregnated with ionic liquids for CO2 adsorption

In this work, the CO₂ adsorption performance of metal-organic frameworks (MOFs) impregnated with ionic liquids (ILs) was studied using quartz crystal microbalance (QCM) at the temperature of 298.15 K and pressures up to 5 bar. The hybrid composites consist of aluminum terephthalate metal-organic framework (AlTp) impregnated of 1-butyl-4-methyl pyridinium and 1-butyl-3-methylimidazolium-based ionic liquids (ILs) with different anions, viz. tetrafluoroborate ([BF₄]^-), thiocyanate ([SCN]^-), chloride ([Cl]^-), and bromide ([Br]^-). ILs-impregnated AlTp synthesized was characterized using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), the thermogravimetry analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. CO₂ adsorption isotherms of the IL/AlTp composites and AlTp were measured to evaluate the ILs effect on the CO₂ adsorption of the AlTp. Comparison of CO₂ adsorption in ILs/AlTp with different anion ([Cl]^-, [Br]^-, [SCN]^-, [BF₄]^-) reveals that CO₂ adsorption in ILs/AlTp was increased in the order as: [BF₄]^- < [SCN]^- < [Br]^- < [Cl]^-. The results show that [BMPyr][Cl]/AlTp the highest CO₂ adsorption capacity, 2.6 times higher than that of AlTp at 5 bar and 298.15 K which helps to guide the logical design of new mixtures for gas separation applications. Also, adsorption/desorption test show that regeneration performance of [BMPyr][Cl]/AlTp is 96.53% after five consecutive cycles adsorption/desorption.

Comprehensive evaluation of ionic liquid [Bmim][PF6] for absorbing toluene and acetone

Absorption is an eminent technology for volatile organic compounds (VOCs) elimination with the merits of high efficiency and low cost. Absorbent plays a critical role in the absorption process, and the thermal stability, saturation capacity, and regeneration performance should be concerned. As a kind of green and eco-friendly solvent, ionic liquid (IL) is expected to be a substitute for the conventional VOCs absorbent. In this study, 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF₆]) is employed to absorb the modeling VOCs (toluene and acetone). Moreover, the used [Bmim][PF₆] is recovered by thermal distillation and the reusability is then conducted by consecutive batch experiments. Based on that, the thermal stability of [Bmim][PF₆] is comprehensively examined, in which the kinetic and thermodynamic parameters are also calculated. Results reveal that [Bmim][PF₆] owned promising toluene absorption performance with inlet concentration of 3000 mg/m³ and flow rate of 300 mL/min at 20 °C, it possesses the saturated adsorption capacity of 5.16 mg/g. [Bmim][PF₆] also shows satisfying thermal stability up to 610 K. In addition, thermal distillation is proved to be a reliable regeneration route on account of the recovered [Bmim][PF₆] remained satisfying capacity even after five cycles.

Thermal Stability of Ionic Liquids: Current Status and Prospects for Future Development

Ionic liquids (ILs) are the safest solvent in various high-temperature applications due to their non-flammable properties. In order to obtain their thermal stability properties, thermogravimetric analysis (TGA) is extensively used to analyze the kinetics of the thermal decomposition process. This review summarizes the different kinetics analysis methods and finds the isoconversional methods are superior to the Arrhenius methods in calculating the activation energy, and two tools—the compensation effect and master plots—are suggested for the calculation of the pre-exponential factor. With both parameters, the maximum operating temperature (MOT) can be calculated to predict the thermal stability in long-term runnings. The collection of thermal stability data of ILs with divergent cations and anions shows the structure of cations such as alkyl side chains, functional groups, and alkyl substituents will affect the thermal stability, but their influence is less than that of anions. To develop ILs with superior thermal stability, dicationic ILs (DILs) are recommended, and typically, [C4(MIM)2][NTf2]2 has a decomposition temperature as high as 468.1 °C. For the convenience of application, thermal stability on the decomposition temperature and thermal decomposition activation energy of 130 ILs are summarized at the end of this manuscript.