Geoscience Reference
In-Depth Information
In recent years, activated carbons showing high surface area are specially impreg-
nated with active metals, like Cd, Cu, W, Cr, and Mo. Such impregnated activated
carbons have additional characteristics, like antibacterial effects, absorb harmful gases
in industrial and military applications
[434]
. The hydrothermal technique is very
effective for the impregnation of active metals into activated carbon. Activated carbon
impregnated with tungsten metal has been successfully employed for the decomposi-
tion of toxic organic compounds, like phenols and nitroarenes
[435,436]
.
Feng et al.
[437
439]
have employed the hydrothermal soft chemical process for
the synthesis of tunnel manganese oxides from a layer of manganese oxide. This
process comprises of two steps: (1) Preparation of a framework precursor with lay-
ered structure and insertion of template ions or molecules (structure directing agents)
into its interlayer space by a soft chemical reaction and (2) transformation of the
template inserted precursor into a tunnel structure by hydrothermal treatment.
Hydrothermal
solvothermal processing helps greatly in the structure stabiliza-
tion of several new compounds
[440,441]
. Natural phyllosilicates are characterized
by a low thermal stability due to the presence of (OH)
2
groups in the lattice.
Through hydrothermal treatment, the replacement of (OH)
2
groups by oxygen
atoms takes place, and this, in turn, improves the thermal stability of phyllosili-
cates. Similarly, the replacement of metals can be carried out under hydrothermal
conditions to obtain new structures.
Recovery, recycling, decomposition, and treatment processes, under hydrother-
mal conditions, are going to play a major role in the twenty-first century
[442
446]
.
Figure 10.90
shows the author's imagination—a new generation, complex industry
constructed underground which will exhaust no toxic or hazardous wastes
[415]
.It
is an ideal closed system, a combination of waste treatment, energy recovery, and
formation of resource. This deals with the recovery process of human waste to
energy resource using hydrothermal technology. The authors have decomposed the
night soil without any insecticides and deodorizers using the hydrothermal
Big town
Silicate soil
adding for diatom
Farm land
Tank
Sewage
Electricity
Fish land
Fertilizer
Underground power plant
(wet combustion system)
Figure 10.90 Author's imagination—a new generation complex industry, constructed
underground and exhausting no toxic or hazardous wastes.
Source: Courtesy of N. Yoshimura.
