PROPERTIES OF 1-BUTYL-3-METHYLIMIDAZOLIUM BROMIDE IONIC LIQUID AND ITS BLENDS WITH WATER AND BROMIDES OF SILVER, COPPER AND TANTALUM
IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA
Ionic liquids with N,N¢-dialkylimidazolium cation characterized now as "green" solvents are investigated intensively to find their practical application. In this research the physical-chemical, electrochemical and corrosion properties of 1-butyl-3-methylimidazolium bromide (BMImBr) and its blends with water and bromides of silver (I), cupper (II) and tantalum (V) were studied. BMImBr is a hygroscopic ionic liquid and in depending on a water content can exists as a solid, liquid, metastable
... cooled melt, and two-phase system – liquid and crystalline hydrate of BМImBr´0.5Н2О composition. At 1:1 components ratio the structural transformation of the melt (СН2О<50 mol%) « the solution (СН2О>50 мол.%) was observed. The BMImBr ionic liquid is a good solvent towards bromides of silver (I), cupper (II) and tantalum (V). These salts destroy the inter- and intramolecular interactions of BMImBr and generate the complex metal-containing ions with Br- anion of ionic liquid. As a result the glass temperature and the density increased, the melting point decreased and on isotherms of dynamic viscosity and specific electro conductivity a distinct minimum was observed at the low concentration range of the salt. Electrochemical window of BMImBr is 1.9 V and it is limited by bromide ions oxidation in the anodic potential range and by imidazolium cations reduction in the cathodic potential range. Additions of the water and the metals salt are an electrochemical active. In their presence the redox processes proceeds inside of the electrochemical window and the discharge-ionization process is the limiting steps. From IL studied the thin films of silver and copper can be deposited with good adhesion on metal substrates including tantalum and titanium. Investigated ionic liquids are a corrosive fluid, and corrosion of the metal increases dramatically in the presence of the same cations.