L. M. Ramenskaya

The Influence of Water on the Physicochemical Characteristics of 1-Butyl-3-methylimidazolium Bromide Ionic Liquid

A modified synthesis of 1-butyl-3-methylimidazolium bromide (BMImBr) was suggested and performed, and some physicochemical properties of the product containing 0.64–13.6 wt % water were determined. Water increased the electrical conductivity and decreased the viscosity and melting point of the substance but weakly influenced its density. Water in amounts of 5–8 wt % (45–50 mol %) caused structural changes. The BMImBr · 0.5H2O crystal hydrate was found to be stable thermodynamically.

Anodic Oxidation of Silver in 1-Butyl-3-Methylimidazolium Bromide Ionic Liquid

Electrochemical oxidation of silver in the 1-butyl-3-methylimidazolium bromide ([BMIm]Br) ionic liquid is studied by cyclic voltammetry, chronopotentiometry, chronoammetry, and gravimetry. Two electrode processes irreversibly proceed on the silver electrode in the potential range studied: the formation of compound [BMIm]+[AgBr2]−, which is soluble in [BMIm]Br, and difficultly soluble AgBr.

Electrochemical behavior of copper in 1-butyl-3-methylimidazolium bromide-copper(II) bromide binary ionic liquid

The methods of potentiometry, voltammetry, and gravimetry are used to study the electrochemical behavior of copper in the BMImBr-CuBr2 ionic liquid (0–30.5 mol % CuBr2). It is shown that electrochemical reduction of copper(II) occurs irreversibly, in two one-electron stages (transfer coefficient α of the cathodic process are 0.58 and 0.46, accordingly, for the first and second stages). Diffusion coefficients of copper-containing ions DCu(II) at 60°C are 1.3 × 10−7 and 1.6 × 10−7 cm2 s−1 in melts with the CuBr2 concentration of 0.1 and 1.5 mol kg−1 of BMImBr, accordingly. High (up to 98%) deposition efficiency and high-quality copper deposit can be obtained in the potential range of −2.0 to −1.8 V (vs. a platinum quasireference electrode). It is found that the copper corrosion rate grows at an increase in the CuBr2 concentration in the binary melt and is comparable with that in aqueous solutions of H2SO4-CuSO4.

Interaction of ionic liquids based on 1-butyl-3-methylimidazolium cation with hydrated cellulose according to the data of infrared spectroscopy

AbstrtactMethods of Fourier-transform infrared spectroscopy and gravimetry were used to study hydrated cellulose films doped with ionic liquids based on the 1-butyl-3-methylimidazolium cation with either chloride, or trifluoroacetate, or bis(trifluoromethylsulfonyl)imid anions. The ionic liquid is retained in the polymer matrix mainly due to the formation of hydrogen bonds between the ionic liquid anion and protons of the hydroxy groups of cellulose, the strength of hydrogen bonding decreasing in the series of [Cl]− > [CF3CO2]− ≫ [N(Tf)2]−.

Electrochemical Properties of the System of Ag—1-Butyl-3-Methylimidazolium Bromide Low- Temperature Ionic Liquid—Silver Bromide

The methods of potentiometry, electrochemical impedance spectroscopy, cyclic voltammetry, and gravimetry were used to study the electrochemical behavior of a silver electrode in low-temperature ionic liquids of BMImBr and BMImBr—AgBr, and also the process of cathodic reduction of Ag(I) compounds out of a BMImBr—AgBr melt. It is shown that an AgBr film is formed on the silver surface and its properties are determined by the ionic liquid composition. It is found that the process of silver electrodeposition from a BMImBr—AgBr binary alloy occurs irreversibly, at a high current efficiency (up to 100%) and a good quality of the deposit at low current densities. At 70°C, the transfer coefficients of the cathodic process (α = 0.56 and 0.16) and diffusion coefficients (DAg(I) = 0.48 × 10−7 cm2/s and 3.3 × 10−7 cm2/s) of silver-containing ions are determined in ionic liquids with the AgBr concentration of 0.81 and 1.53 mol/kg BMImBr, accordingly.

Immobilization of imidazolium cation based ionic liquids on thin polymer films

Methods of gravimetry, optical microscopy, FTIR spectroscopy, and conductometry were applied to the study of the adsorption of the following ionic liquids: 1-butyl-3-methylimidazolium chloride, bistrifluoromethylsulfonylimide, and trifluoroacetate on thin-layer films of polymers of different nature including polypropylene, polyethylene terephthalate, polytetrafluoroethylene, poly(vinyl chloride), and hydrated cellulose. It was established that the hydrated cellulose film can serve as polymer matrices for the ionconducting 1-butyl-3-methylimidazolium halide salts. The hydrated cellulose additive in the ionic liquids promotes their immobilization on the poly(vinyl chloride) film.

The Physicochemical Characteristics of the 1-Butyl-3-methylimidazolium Bromide-Polyethylene Glycol-Water System

Mixtures of 1-butyl-3-methylimidazolium bromide (BMImBr) with polyethylene glycol (PEG) (molecular weights 1500 and 40000) containing 4–74 wt % BMImBr were studied. Thermogravimetric and differential scanning calorimetry measurements showed that the compatibility of BMImBr and PEG improved as the molecular weight of the polymer decreased. At a BMImBr: PEG1500 weight ratio of 1: 3, a phase-stable composite formed. The results of conductometric measurements were used to determine the diffusion coefficients D± and conductivity f of BMImBr in mixtures. BMImBr behaved as a strong electrolyte in the mixtures under consideration. Cyclic voltammetry with a platinum electrode was used to show that, as distinct from the BMImBr-H2O system, water in the BMImBr-PEG1500-H2O system did not exhibit electrochemical activity within the “electrochemical window” of BMImBr.

Electrochemical oxidation of tantalum and niobium in 1-butyl-3-methylimidazolium bromide melt containing water admixtures

The niobium and tantalum anodic oxidation is studied using electrochemical methods in a ionic liquid, 1-butyl-3-methylimidazolium bromide (BMImBr), containing water admixtures. It is found that resistive oxide layers are formed on the metal surface in the polarization process and their growth follows the complicated parabolic or inverse logarithmic laws. It is shown that under the given conditions, the chemical stability of oxide layers on niobium is considerably lower than that on tantalum.

Electrochemical properties of 1-butyl-3-methylimidazolium bromide melt containing water impurities

AbstractThe effect of a water impurity (1.8–10 wt %) on the conductivity of the ionic liquid-H2O binary system was studied in a wide temperature range. It was shown that the interaction between components is characteristic of this system, and the molar ratio of components 1: 1 is boundary between the structures of solution and melt. The basic kinetic features of electrochemical reduction of water of the BMImBr-H2O binary system were determined by voltammetry with linear potential sweep. The transfer coefficient for the cathodic process (α = 0.46) and H2O molecule diffusivities were determined depending on the water content (