(397m) Defluoridation of Water Using Amine Functionalized Cellulose Nanofibers

Fluoride
content in potable water that is higher than the World Health Organization (WHO)
limit of 1.5 mg L^-1, can cause fluorosis [1]. As groundwater in several
countries is affected by excess fluoride content, there is a great need for the
treatment of fluoride contaminated water [2]. Several defluoridation techniques
such as adsorption, ion exchange, coagulation-precipitation, and membrane
process have been reported in the literature. However, adsorption technique is widely
studied because of its economic viability, easy operation, low maintenance cost
and efficiency of fluoride ion removal [3-5].

In
this study, we have investigated the fluoride removal capacity of amine-functionalized
cellulose nanofibers derived from modified electrospun cellulose acetate fibers
under batch conditions. Electrospun cellulose acetate nanofibers were modified
by the deacetylation process to get the cellulose fibers. Further, the surface
of cellulose fibers was functionalized with amine functional groups using
ethylenediamine to improve its binding capacity for fluoride ions. Thus prepared
adsorbent was characterized with field emission scanning electron microscopy
(FESEM), Fourier transform infrared spectrophotometer (FT-IR) and Brunauer-Emmett-Teller
(BET) surface analyzer.

Figure
1: SEM images of electrospun cellulose acetate fibers at different
magnifications

Batch
adsorption experiments were performed as the function of contact time, the
dosage of adsorbent, initial fluoride concentration, temperature, and pH.
Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were applied to
the equilibrium data and adsorption kinetics were tested by pseudo-first-order
and pseudo-second-order kinetic models to determine the best-fit of sorption kinetics.
To regenerate the adsorbent, desorption experiments were carried out for
fluoride adsorbed nanofibers at various pH values by adding 0.1 M HCl or 0.1 M
NaOH. Finally, the prepared adsorbent was successfully used for the field water
sample collected from a nearby fluoride affected village.

References:

1.    
World Health Organization. Guidelines for
drinking-water quality, First addendum to third addition, Vol. 1,
Recommendations.-3^rd ed.

2.    
Jagtap, S., Yenkie, M.K., Labhsetwar, N., and
Rayalu, S. Fluoride in drinking water and defluoridation of water, Chem. Rev. 2012,
112, 2454-2466.

3.    
Meenakshi, Maheshwari, R.C. Fluoride in drinking
water and its removal, J. Hazard. Mater. 2006, B137, 456-463.

4.    
Gupta, V.K., Ali, I., Saini, V.K. Defluoridation
of wastewaters using waste carbon slurry, Water Res. 2007, 41,
3307-3316.

5.    
Chen, N., Zhang, Z., Feng, C., Li, M., Zhu, D.,
Chen, R., Sugiura, N. An excellent fluoride sorption behavior of ceramic
adsorbent, J. Hazard. Mater. 2010, 183, 460-465.