1070-4272/05/7811-1791C2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 11, 2005, pp. 1791!1794. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 11,
2005, pp. 1824!1826.
Original Russian Text Copyright C 2005 by Tseluikin, Solov’eva.
OF SYSTEMS AND PROCESSES
Viscous Flow of Concentrated Aqueous Solutions
V. N. Tseluikin and N. D. Solov’eva
Technological Institute, Saratov State Technical University, Engels, Saratov oblast, Russia
Received February 17, 2005; in final form, September 2005
Abstract-The dynamic viscosity, apparent molar volume, enthalpy, and Gibbs energy of activation of a vis-
cous flow of concentrated aqueous solutions of NiCl
were calculated. The concentration dependences
of these parameters were analyzed in terms of structural transformations. A polynomial approximation of
the concentration dependences of the dynamic viscosity of the solutions under study was performed using
MATLAB 6.1 software package.
The internal friction in a fluid, the energy of inter-
action between particles, and structural transforma-
tions occurring when the concentration and tempera-
ture of a solution are changed can be characterized by
analyzing the dynamic viscosity . Previously we
studied the viscous flow of NiSO
tions . The aim of this study was to examine the
concentration dependences of the dynamic viscosity of
a two-component solution of NiCl
constant concentration of iron(II) chloride (1.20 M).
These salts are the main components of chloride elec-
trolytes used in deposition of the iron3nickel alloy.
The dynamic viscosity h (cP) was calculated using
h = nr,
where n is the kinematic viscosity (cSt), and r is
density (g cm
The kinematic viscosity was determined using
a VPZh viscometer with a capillary diameter of
0.56 mm [GOST (State Standard) 10028381]. The
density was measured pycnometrically. The measure-
ment error was 0.23 0.4%. The reproducibility of the
experimental results was confirmed by calculating
the Cochran test .
The competitive action of disrupting and stabilizing
factors leads to a nonmonotonic run of the concentra-
tion dependences of the dynamic viscosity of the
solutions under study (Fig. 1). It is known [6, 7] that,
when penetrating into structural voids of water, ions
with crystallographic radii exceeding 0.130 nm (void
size) deform these voids and rupture hydrogen bonds
between molecules. The radius of the Cl
0.181 nm , and, apparently, chloride ions charac-
terized by negative hydration will disrupt the structure
of the solvent. However, Ni
radii are 0.074 and 0.080 nm, respectively, will sta-
bilize the solution structure by being freely accommo-
dated in the voids and binding free water molecules
into hydrate complexes. The considerable increase in
the viscosity of two-component solutions at NiCl
concentrations of 3.1033.86 M (Fig. 1) is probably
due to formation of a new structure of the solution,
constituted by hydrated ions bound together by hy-
The significant changes in the structure of NiCl
solutions are indicated by the nonlinear concen-
tration dependence of the apparent molar volume F
Fig. 1. Dynamic viscosity h vs. the concentration c of
in a solution with 1.20 M FeCl
. T (oC): (1) 20,
(2) 30, (3) 40, (4) 50, (5) 60, and (6) 70.