Ceramics for Sustainable Energy Technologies with a Focus on Polymer-Derived Ceramics - Novel Combustion Concepts for Sustainable Energy Development - page 496

primarily based on zeolites or silica — poses a promising alternative to conventional

chemical absorption techniques (D Alessandro et al. 2010 ).

In the application of porous ceramics for liquid media

'

filtration, e.g., for water
purification, chemical inertness and favorable anti-fouling properties are major
advantages. Filters prepared from Al 2 O 3 , SiC, and TiO 2 present economical solu-
tions for conventional filtration as well as for micro- and ultra- filtration A modi-

filters with metals or organic encapsulating compounds
permits the removal of a wide variety of pollutants, including heavy metals,
radioactive compounds, or complex organic compounds. Recent developments in
the

fication of these inorganic

field of photocatalysis, primarily involving nanoscaled TiO 2 , have also shown
great potential for the removal of organic contaminants present at low levels

(Yu et al. 2007 ).
A speci

c environmental application for ceramics and glass ceramics is
hazardous waste remediation in the form of immobilization of both conventional
and radioactive wastes. Immobilization involves the chemical incorporation of
waste products into a suitable matrix, e.g., glass, in order to prevent further release.
While the vitri cation of nuclear wastes in glass is suitable in most cases, some

types of high-level waste, especially refractory and volatile wastes, require more
advanced techniques involving the use of crystalline ceramic (monazite, zirconia,
zircon, among others) or glass ceramic immobilization materials. The use of geo-
polymers, a family of compounds in the alumino-silicate system, has been proposed
as an economic and sustainable alternative for the immobilization of hazardous,
toxic, or nuclear wastes (Komnitsas and Zaharaki 2007 ).
Advanced ceramic-based sensor systems allow not only for the monitoring of
hazardous species or pollutants, but are also bene ciency and

emission control in industrial processes. Progress in the technological

cial for energy ef

field of
advanced ceramic sensors aims toward the development of low-cost sensors with
quick response times, high sensitivity, and high reliability, even in harsh envi-
ronments, permitting the detection of a wide variety of gases such as O 2 , CO, CO 2 ,
NO x , or hydrocarbons. Next to well-established sensor systems such as YSZ-based
potentiometric oxygen sensors for automotive applications, examples for ceramic
sensors include semiconducting CO sensors made of SnO 2 , electrochemical CO 2
sensors containing Li 3 PO 4 as electrolyte, or electrochemical NO x sensors, also
based on YSZ (Akbar et al. 2006 ).

1.1.6 Energy Conservation

The ef cient use of both conventional and renewable energy carriers is a primary

factor contributing to current energy conservation efforts. One way to increase the
ef

ciency in combustion processes is the operation at higher process temperatures.
This, in turn, results in increased demands on the thermal and structural properties
of the materials used in these processes.
Ceramic thermal barrier coatings (TBC) are used in a variety of applications,
including gas turbines, in order to protect underlying metallic or composite