Adsorptive removal of fluoride by micro-nano hierarchical web of activated carbon fibers

Abstract

This study describes the development of aluminum impregnated hierarchal web of carbon fibers for the removal of dissolved fluoride in water. Micrometer-sized activated carbon fibers (ACF) were used as a substrate to grow carbon nanofibers (CNF) by chemical vapor deposition (CVD) using Ni as a catalyst. The hierarchal web of micro-nanocarbon fibers (ACF/CNF) thus prepared was impregnated with aluminum (in its metallic state) and then tested for the adsorption of fluoride ions over the concentration range of 1-50 ppm in water under both batch and flow conditions. The adsorbent web showed significant adsorption of fluoride ions. In addition, the total fluoride uptake was observed to be larger on aluminum impregnated ACF/CNF web than on its parent material, the ACF alone impregnated with Al. Various analytical techniques including the scanning electron microscopy (SEM), Raman spectroscopy, and the elemental analyzer were employed to characterize the Al-impregnated ACF/CNF. The SEM images showed a complex 3D network of nanofibers uniformly deposited with Al. This study is a step in developing a general platform suitable for producing potable water that also specifically addresses the problem of fluoride removal.