Geoscience Reference
In-Depth Information
synthesis and processing under a new concept called green materials, which deals
with industrial ecology, environmentally friendly methods, recycling, and so on.
In this regard, hydrothermal technique occupies a unique place because of its
pollution-free nature as the reactions take place within a closed system. Also, the
reactions take place at relatively lower pressure/temperature conditions, which
make the technique more popular and easier to operate.
10.9 Hydrothermal Technology for the Twenty-First Century
Belching smokestacks were viewed as a sign of progress in the nineteenth century,
worldwide, and even now, in some developing countries. Industrialization, indeed,
should be viewed as a sign of progress. It leads to higher living standards, greater
longevity, and a better quality of life.
Of late, we have begun to understand the implications of pollution and its pre-
vention, of population growth, and increased industrialization in the third world
and in the vibrant Pacific Rim economies. By the middle of the twenty-first cen-
tury, the population will increase by at least by 50% and then probably stabilize as
most countries will have relatively high standards of living. Industrial production
will probably increase at least five fold as the newly industrialized nations will
have formed a mainstream
[416]
.
Modern human society has been sustained both by a remarkable development of
advanced materials and by a huge consumption of energy and resources. As we
cannot withdraw ourselves from using them now and even in the near future, the
wastes of materials, chemicals, energy, and heat would increase markedly to cause
environmental problems on the earth (
Figure 10.87
)
[417]
. The global environment
has great effects on human lives. Far-reaching changes in social structure are being
forced upon us already by environmental issues such as global warming, desertiza-
tion, depletion of the ozone layer, and acid rain, which stem from two main pro-
blems: global scale expansion of the economic activities of industrially advanced
nations and population expansion in developing countries. Global environmental
problems will lead to great changes in the social structure of the twenty-first cen-
tury. These changes will not only affect human life and industrial activity but also
force significant reforms in fundamental concepts of manufacturing goods
[418]
.
As the earth is almost a closed system with limited biosphere, lithosphere, hydro-
sphere, and atmosphere (
Figure 10.88
), all materials should be cycled, and moreover,
heat and energy (entropy) loss should be minimized
[417,419]
. Considering these spe-
cifications, we must search for materials (1) that are less hazardous to human life, and
preferably compatible with human beings and other living species, and (2) which have
environmentally friendly processing to fabricate, to manipulate, to treat, to reuse, to
recycle, and to dispose of those materials. The term materials cycle is generally used
to designate raw materials synthesis, their fabrication, functional products, and their
disposal. It is well known that all materials are extracted from the earth and then con-
verted into functional products through various means of materials processing, usually
