Aqueous solutions of divalent chlorides: Ions hydration shell and water structure

Abstract

By combining neutron diffraction and Monte Carlo simulations, we have determined the microscopic structure of the hydration ions shell in aqueous solutions of MgCl(2) and CaCl(2), along with the radial distribution functions of the solvent. In particular the hydration shell of the cations, show cation specific symmetry, due to the strong and directional interaction of ions and water oxygens. The ions and their hydration shells likely form molecular moieties and bring clear signatures in the water-water radial distribution functions. Apart from these signatures, the influence of divalent salts on the microscopic structure of water is similar to that of previously investigated monovalent solutes, and it is visible as a shift of the second peak of the oxygen-oxygen radial distribution function, caused by distortion of the hydrogen bond network of water.

Strong correlations between structural order and passive state at water–copper oxide interfaces

“…In terms of corrosive aqueous environments, the presence of halide anions can profoundly alter the structure and dynamics of interfacial water layers [18,33]. While the solvation characteristics of interfacial layers are expected to play an important role in corrosion initiation, they have received much less attention to date [7,33]. Recently, we have shown that ionic solvation of water near passive oxides could also play an important role in influencing halide ion adsorption and transport [18].…”

“…Additionally, there are several important questions pertaining to solvation dynamics near electrochemical interfaces, ionic transport across electrochemical double layers as well as interfacial molecular order in a typical electrochemical environment that are not yet well understood [7][8][9].…”

Communication: Electronic structure of the solvated chloride anion from first principles molecular dynamics

“…37 position of the first maximum (r max ) and minimum (r min ) of the Cl−O and Cl−D pair correlation functions and the corresponding coordination numbers are reported in Table I, together with experimental values. The latter ones differ depending on the technique used (i.e., neutron diffraction or X-ray measurements) and the type of counterions present in the solution, 5,6,[36][37][38][39][40][41] whose effect however appears to be minor. The dependence of experimental data on concentration is instead more pronounced (at least for the Cl−D coordination).…”

How safe is to safely enter in the water no-man's land?

“…Details about the sample preparation and data analysis can be found in refs. [16][17][18] and [12,19,20] for salt solutions and confined water, respectively. The BBD spectroscopy experiments have been performed at our home laboratories, by using different confining media for water, namely a powder of lysozyme protein at hydration h= 0.30 g/g (grams of water per gram of dry material) and two silica substrates (xerogel and MCM41) at hydration h = 0.57 g/g and 0.43 g/g, respectively.…”