Page 532 - Polymer-based Nanocomposites for Energy and Environmental Applications

Polypyrrole-based nanocomposite adsorbents 485

17.15 Summary and future outlook

This chapter presented polypyrrole CP as a class of polymer that has versatile appli-
cations in different fields of human endeavor. Incorporation of nanomaterials in poly-
pyrrole matrix to form polymer nanocomposites has been described as an important
route to enhance the properties of traditional polypyrrole for different applications.
The chapter featured polypyrrole-based materials as suitable candidates for the reten-
tion of contaminants from their aqueous solutions. In particular, efforts were made to
review the literature on the applicability of polypyrrole-based nanocomposite adsor-
bents for the removal of radiocations from liquid radioactive wastes. However, more
than half of those available studies have applied nonradioactive cations in their stud-
ies. This may be related to the difficulties and limitations of handling liquid radioac-
tive wastes. Considering the high sorption capacities reported for various
contaminants, it is no doubt that polypyrrole-based nanocomposites will have poten-
tial use in liquid radioactive waste treatment such as nuclear waste effluents from
nuclear power plant operation and those from nuclear medicine or radioactive
laundry waste.
Based on the literature, many of the important variables that describe adsorption
behaviors of contaminants from waste solutions, such as solution pH, contact time,
cation concentration, temperature, adsorbent composition and concentration, compo-
sition of waste solution, and interfering ions, have been few considered. The available
information suggests that some of these variables play a significant role on the cat-
ionic/adsorbent interactions, but it is somewhat difficult to draw general conclusion
except that the variables have been considered independently. Apart from this, as there
are limited studies on liquid radioactive wastes, it would be desirable to see studies
that consider radioactive solutions, radiation effect, thermal effect, and/or the pres-
ence of decay products from the radioisotopes that may introduce other variables
in the sorption system.
Besides, the limited availability of high-quality nanomaterials coupled with high
cost of production is still a challenge to the use of most nanomaterials for the
preparation of polypyrrole-based nanocomposite adsorbents, and also, processing
of polypyrrole-based nanocomposites is somewhat challenging to achieve high
adsorption performance. A great deal of care and expertise is needed to control the
dispersion and orientation of many nanomaterials in order to optimize polypyrrole
nanocomposite performance for adsorption. Hence, there is still an urgent need for
further explorations of different low-cost nanomaterials, so that more cost-effective
and/or environmentally friendly materials can be developed and utilized.
In conclusion, more studies on the fabrication of polypyrrole-based nanocomposite
materials for adsorption are desirable. As adsorption studies on the applications of
polypyrrole-based nanocomposite adsorbents are still largely laboratory-based, indus-
trial application will be desirable, which will help to address many other issues that
may arise during mass production of these adsorbents and their implementation in
adsorption of radioactive materials from their radioactive waste solutions.