Fe-Grown Carbon Nanofibers for Removal of Arsenic(V) in Wastewater

An Fe-impregnated hierarchal web of carbon fibers was synthesized and evaluated as an adsorbent for arsenic(V) removal from wastewater. The web was prepared by growing carbon nanofibers (CNFs) on the activated carbon microfibers (ACFs) by chemical vapor deposition (CVD) using Fe as a catalyst. Fe was found to play a bifunctional role in the development of the micro-/nanoweb of carbon fibers: (1) as a catalyst for growing CNFs and (2) as an adsorbent for removing arsenic(V) from water. The method of preparation consisted of impregnation of substrate ACFs with ferric chloride, calcinations followed by reduction to convert oxides of Fe to the metallic state, growth of CNFs by CVD, and subsequent mild sonication of the web to open its pore spaces. The Fe-impregnated adsorbent was tested for the removal of arsenic(V) over the concentration range of 1-50 mg/L in water under both batch and flow conditions. The results showed comparable or greater removal of arsenic(V) compared to that obtained with commercial adsorbents. The prepared adsorbent was characterized by various analytical techniques such as BET area and pore size distribution (PSD), elemental analysis, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis.