Hollow Polyaniline Microsphere/Fe3O4 Nanocomposite as an Effective Adsorbent for Removal of Arsenic from Water
Soumi Dutta, Kunal Manna, Suneel Kumar Srivastava, Ashok Kumar Gupta, Manoj Kumar Yadav
Abstract
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.