Hollow Polyaniline Microsphere/Fe(3)O(4) Nanocomposite as an Effective Adsorbent for Removal of Arsenic from Water

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.