Kochmarskii V.
PhD in Physics, supervisor of Physical and Technological Laboratory of Aqueous
Systems (PTLAS), National University of Water and Environmental Engineering, Rivne,
Ukraine
Melnyk V.
Senior lecturer, National University of Water and Environmental Engineering,
Rivne, Ukraine
FORMATION OF CALCIUM CARBONATE FROM MODEL
SOLUTIONS. THEORETICAL AND EXPERIMENTAL INVESTIGATIONS
Introduction. Comprehension of physical and chemical foundations of calcium
carbonate crystallization process except theoretical scientific interest in crystallization
that is accompanied by chemical reactions [1-6] is of practical significance [7-9] for
many branches of water engineering. For example, solid CaCO
3
formation is important
channel of CO
2
removal from its circulation in nature. Modeling of the process of solid
CaCO
3
formation is important to comprehend the ways of CO
2
greenhouse gases
conservation in the form of sedimentary oceanic carbonates. The process of mud
injection of oil and water producing wells is connected with CaCO
3
formation. Of
importance is the development of the ways of preventing solid precipitation on
boundary surfaces having contacts with water medium where such precipitation
deteriorates the conditions of water transport or precipitation on heat exchanging
surfaces that reduces heat exchangers efficiency and causes energy resources losses
and equipment service life reduction.
The purpose of the paper is the development and analysis of physical, chemical
and mathematical models of the process of controlled carbonate crystallization in
quasiequilibrium approximation and the dynamic model of the process; comparison
of the model calculations with the experimental results to determine the boundaries of
quasiequilibrium approximation and the suggested dynamic models use.
Formulation of general model of CaCO3 formation process. Analyze an open
calcium-hydrocarbonate system like:
"CaCl
2
+ NaHCO
3
+ HOH + CO
2
",
that exchanges carbon dioxide CO
2
with the environment and where solid calcium
carbonate formation is possible. Let us consider that pH < 10 in the given CHCS.
Indicate components concentrations of the system, mol/dm
3
,
.
X
X
X
Sc
:
sum
Carbonat
(1)
],
[CaCO
X
,
]
[CaHCO
X
,
]
[CaCO
X
],
[Ca
X
],
[H
X
O],
[H
X
],
Cl
[
X
],
[OH
X
],
[CO
X
],
[CO
X
],
[HCO
X
3
2
1
0
3
38
3
18
3
10
2
8
7
2
6
-
5
-
4
2
3
3
2
2
3
1
+
+
=
=
=
=
=
=
=
=
=
=
=
=
+
+
+
−
−
- 1370 -