Hollow Polyaniline Microsphere/Fe3O4 Nanocomposite as an Effective Adsorbent for Removal of Arsenic from Water

Abstract Polyaniline hollow microsphere (PNHM)/Fe 3 O 4 magnetic nanocomposites have been synthesized by a novel strategy and characterized. Subsequently, PNHM/Fe 3 O 4 -40 (Fe 3 O 4 content: 40 wt.%) was used as an adsorbent for the removal of arsenic (As) from the contaminated water. Our investigations showed 98–99% removal of As(III) and As(V) in the presence of PNHM/Fe 3 O 4 -40 following pseudo-second-order kinetics ( R 2 > 0.97) and equilibrium isotherm data fitting well with Freundlich isotherm ( R 2 > 0.98). The maximum adsorption capacity of As(III) and As(V) correspond to 28.27 and 83.08 mg g −1 , respectively. A probable adsorption mechanism based on X-ray photoelectron spectroscopy analysis was also proposed involving monodentate-mononuclear/bidentate-binuclear As-Fe complex formation via legend exchange. In contrast to NO 3 − and SO 4 2− ions, the presence of PO 4 3− and CO 3 2− co-ions in contaminated water showed decrease in the adsorption capacity of As(III) due to the competitive adsorption. The regeneration and reusability studies of spent PNHM/Fe 3 O 4 -40 adsorbent showed ~83% of As(III) removal in the third adsorption cycle. PNHM/Fe 3 O 4 -40 was also found to be very effective in the removal of arsenic (<10 μg L −1 ) from naturally arsenic-contaminated groundwater sample.