Modeling VLE and LLE of Deep Eutectic Solvents (DES) and Ionic Liquids (IL) Using PC-SAFT Equation of State. Part II

This study aims to use Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) to describe the phase behavior of systems containing DESs and ILs. The DESs are based on Tetrabutylammonium chloride ([N4444]Cl) and Tetrabutylammonium bromide (TBAB) as hydrogen bond acceptors, and levulinic acid (LevA) and Diethylene Glycol (DEG) as hydrogen bond donors in the mole ratio of 1:2 and 1:4, respectively. The predicted phase equilibrium data from PC-SAFT has been compared to those from COSMO-RS and NRTL predictions. ILs studied in this work are low viscosity ether-functionalized pyridinium-based ILs [EnPy][NTf2] and [CmPy][NTf2], while 1-(2-methoxyethyl)-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)-amide) ([COC2mPYR][NTf2]) and 1-propyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide ([Pmim][NTf2]) were used for the study of the LLE systems with n-heptane + thiophene and n-hexane + ethylbenzene, respectively. In the last part, mixtures of linear alkanes and perfluoroalkanes have been studied to predict the phase behavior of perfluoroalkylalkanes with their linear alkane counterparts and comparisons have been made against SAFT-Mie pair potential.

Exchange Counterion in Polycationic Hydrogels: Tunability of Hydrophobicity, Water State, and Floating Capability for a Floating pH Device

Smart gel materials are capable of controlling and switching swelling, water state, and wettability properties triggered by external stimuli. In this study, we fabricated a series of polyelectrolyte hydrogels bearing a 3-trimethylammoniumpropyl pendant to a methacrylamide-based backbone and examined the switchability with hydrophobic-like counteranions. The exchange between the initial chloride and camphor sulfate (CaS), dodecyl sulfate (DS), and perfluorooctanoate (PFO) counterions was investigated. The kinetics of the exchange showed that the fast exchange (within 4 h) of PFO allowed for a favorable coordination for ion pairing, resulting in a decrease in hydration. The reversibility of the exchange to the Cl- ion was only enabled for the CaS ion due to its bulkiness, while the PFO and DS hydrogels were unable to exchange, even by using tetrabutylammonium chloride, which is a structurally similar reagent, due to aggregation or the coagulates in the collapsed state of the linear tails of the counterions. The hydrogels exhibited a modulable water state and water swelling. Moreover, the hydrogels containing DS and PFO, as counterions, showed surface hydrophobic (contact angle 90°) and high hydrophobic (110°) behavior, respectively. The Raman spectrometry fluorescence with a pyrene probe indicated an increase in strong hydrogen-bonded water molecules, water confinement, and hydrophobic domains in the PFO hydrogel. Moreover, the PFO-modified hydrogel demonstrated a free-floating ability on the water surface, with a strong water repellency, showing that it has the potential to be applied in a floating pH detection device to distinguish between volatile and nonvolatile bases in a controlled manner.

Bulk assembly of 0D organic tin(II) chloride hybrid with high anti-water stability

A lead-free compund of (TBAC)SnCl3 (TBAC = tetrabutylammonium chloride) with high anti-water stability was reported, which can be stable in water for 24 hours. Upon photoexcitation, this compound exhibits a...

Branched nanofibers with tiny diameters for air filtration via one-step electrospinning

Engineering the surface morphology of fibers has been attracting significant consideration in various areas and applications. In this study, polyvinylidene fluoride (PVDF) branched nanofibers with a diameter of less than 50 nm are electrospun directly at a low relative humidity by adding tetrabutylammonium chloride. The effects of the branched structure on the specific surface area and pore size distribution are investigated, and the filtration properties of the air filter based on branched nanofiber webs with different basis weights are studied. The results exhibit that the air filter based on PVDF branched nanofibers with the basis weight of 1 g/m2 has an outstanding filtration efficiency (99.999%) to 0.26 µm sodium chloride particles under the pressure drop of 126.17 Pa. We believe that this study can be used as a useful reference for the preparation of branched nanofibers through one-step electrospinning.

Generation and Reactivity of a NiIII2(μ-1,2-peroxo) Complex

Ni-based oxide materials are promising candidates for catalyzing the oxygen evolution reaction. The detailed mechanism of water splitting in these systems has been of interest with a goal of understanding the intermediate species vital for catalytic activity. A potential intermediate species prior to release of oxygen is a bridging Ni^III₂(<i>μ</i>-1,2-peroxo) complex. However, Ni₂(<i>μ</i>-1,2-peroxo) complexes are rare in general and are unknown with oxidation states higher than Ni^II. Herein, we report the isolation of such an unusual high-valent species in a Ni^III₂(<i>μ</i>-1,2-peroxo) complex, which has been characterized using single-crystal X-ray diffraction and X-ray absorption, NMR, and UV-vis spectroscopies. In addition, treatment with excess tetrabutylammonium chloride results in regeneration of the precursor Ni–Cl species, implicating the reversible release of oxygen or a reactive oxygen species. Taken together, this suggests that Ni^III₂(<i>μ</i>-1,2-peroxo) species are accessible and may be viable intermediates during the oxygen evolution reaction.

Generation and Reactivity of a NiIII2(μ-1,2-peroxo) Complex

Ni-based oxide materials are promising candidates for catalyzing the oxygen evolution reaction. The detailed mechanism of water splitting in these systems has been of interest with a goal of understanding the intermediate species vital for catalytic activity. A potential intermediate species prior to release of oxygen is a bridging Ni^III₂(<i>μ</i>-1,2-peroxo) complex. However, Ni₂(<i>μ</i>-1,2-peroxo) complexes are rare in general and are unknown with oxidation states higher than Ni^II. Herein, we report the isolation of such an unusual high-valent species in a Ni^III₂(<i>μ</i>-1,2-peroxo) complex, which has been characterized using single-crystal X-ray diffraction and X-ray absorption, NMR, and UV-vis spectroscopies. In addition, treatment with excess tetrabutylammonium chloride results in regeneration of the precursor Ni–Cl species, implicating the reversible release of oxygen or a reactive oxygen species. Taken together, this suggests that Ni^III₂(<i>μ</i>-1,2-peroxo) species are accessible and may be viable intermediates during the oxygen evolution reaction.