Abstract
Ph.D. (Chemistry)
The exponential increase in global population and rapid industrialization have been
identified as two prime concerns of the modern world which are continually upsetting the
earth’s ecology by introducing various xenobiotic substances into different spheres of the
ecosystem. Water as an essential component of the ecosystem and a precious resource to
support human life serves as an “absolute sink” for many of these externally introduced
contaminants. Amongst the various water resources, groundwater constitutes 97 % of the
globally available freshwater and serves as the only economically feasible source of drinking
water for more than 50 % of the world population. However, the drinking water quality is
deteriorating at an alarming rate due to the presence of various toxic water pollutants like
lead (Pb), chromium (Cr), mercury (Hg), arsenic (As), nitrate (NO3
-) and fluoride (F-) in
ground or surface water more than their standard allowable limits set by various health
organizations. Fluoride (F-), as one of the vital micronutrients, has a significant prophylactic
effect over dental and bone health in humans up to a certain extent (1.0-1.5 mg/L) as
stipulated by World Health Organization (WHO). However, prolonged exposure to
excessive fluoride intake becomes detrimental to dental and skeletal health, as well as leads
to various non-skeletal manifestations. Hence, it is a prerequisite to alleviate excess fluoride
in drinking water to bring down its concentration to standard permissible limits, and in
reference to the same over the last few decades, several water defluoridation technologies
have been developed such as precipitation/coagulation, membrane based processes, ion
exchange and adsorption. The critical assessment of these techniques has revealed that
adsorption serves as technically most simple, easy to handle, economic, and reliable system
for providing fluoride free drinking water and thus has emerged as a most captivating and
widely employed defluoridation technique in fluoride stricken areas of developing countries.
The efficacy of an adsorption system is mainly governed by the adsorbent, and as a result,
over past few years, various materials have been documented as promising fluoride
adsorbents. Although each adsorbent has its unique superior characteristics, however the
drawbacks associated with several conventional adsorbents such as low adsorption capacity,
poor mechanical stability and narrow working pH range have been visibly noted in the
defluoridation research. The present study was therefore undertaken to address the above
issues, where the intrinsic ion-exchange behaviour and unique electrochemical properties of
conducting polymers encouraged the investigation and exploration of their fluoride...