Geoscience Reference
In-Depth Information
Figure 4.15 Kinetic curves of
malachite dissolution in ammonia
aqueous solutions at 20
C and
75
C
[106]
.
(a) at 20°C
3M
40
2M
20
1M
0
40
80
120
Hours
(b) at 75°C
30
3M
2M
20
1M
10
0
20
40
60
80
100
120
Hours
shows kinetic curves of malachite dissolution in ammonia aqueous solutions at
20
C (a) and at 75
C (b) respectively. As can be seen from
Figure 4.15
, equilibrium
copper contents in the ammonia solutions increase as ammonia concentration
increases and they decrease as temperature rises.
These examples give a more or less complete picture with regard to the type of
solvent, the PT conditions, and the progress made in the search for new solvents
for various inorganic compounds under hydrothermal conditions. All these studies
yield crystal growth kinetics, the phase-pure product.
Thus, hydrothermal physical chemistry is a fast growing field that is going to play
a key role in the twenty-first century in the preparation of future materials. The physi-
cochemical data will provide an insight into the actual hydrothermal reaction mecha-
nism and in turn will bring down the PT conditions of the preparation of materials.
4.6 Thermodyanmic Calculations for the Intelligent
Engineering of Materials
Hydrothermal research has significantly changed in the twenty-first century with
researchers giving up the Edisonian trial and errors approach for designing hydro-
thermal experiments, which is highly time consuming and very expensive due to
frequent failures in experimental results. It is well known that the hydrothermal
