Abstract:
The main objective of this study was to examine fluoride adsorption potential of thermally activated
termite mound (TTM) under batch adsorption experimentalsetup. Thermal activation of the mound in between
100 to 5000C increased the adsorption efficiency (~ 50 to ~ 79%), whereas activation above 5000C decreased
the efficiency. The removal of fluoride was optimal (~ 91%) in the pH ranging from 3 to 10. Adsorption kinetics
data followed pseudo-second order equation (R2> 0.99). Freundlich and Dubinin-Radushkevich isotherms
satisfactorily described the equilibrium isotherm data (R2> 0.98, χ2< 0.25). The obtained mean sorption energy,
EDR, was 11.12 kJ/mol suggesting chemisorption as the predominant sorption mechanism. Fluoride adsorption
was significantly decreased in the presence of CO3
2-
and PO4
3-
at a higher concentration range. TTM effectively
reduced 7.56 mg/L fluoride in groundwater to below 1.5 mg/L. Fluoride loaded adsorbent was successfully
regenerated with NaOH solution for effective reuse. The results of this study demonstrated that TTM could be a
promising defluoridation material requiring further investigation for practical applicability.
