title: Arsenic removal from water using flame-synthesized iron oxide nanoparticles with variable oxidation states.
abstract: We utilized gas-phase diffusion flame synthesis, which has potential for large-scale production of metal oxide nanoparticles, to produce iron oxide nanoparticles (IONPs) with variable oxidation states. The efficacy of these materials in removal of arsenate (As(V) ) from water was assessed. Two different flame configurations, a diffusion flame (DF) and an inverse diffusion flame (IDF), were employed to synthesize six different IONPs by controlling flame conditions. The IONPs produced in the IDF configuration (IDF-IONPs) had smaller particle diameters (4.8 - 8.2 nm) and larger surface areas (141-213 m2/g) than the IONPs produced in the DF configuration (29 nm, 36 m2/g), which resulted in their higher adsorption capacities. As(V) adsorption capacities of the IDF-IONPs increased when the IONPs were synthesized in more oxidizing conditions. The fully oxidized IDF-IONPs, maghemite (γ-Fe2O3), showed the highest As(V) adsorption capacity, comparable to that of magnetite nanocrystals synthesized by thermal decomposition of iron pentacarbonyl and equivalent to three to four times higher capacity than that of a commonly used goethite-based adsorbent. All IONPs were magnetically responsive, which is of great importance for solid-liquid separation. This study demonstrates that the IONPs synthesized in gas-phase flame, particularly IDF-IONPs, are excellent adsorbents because of their high As(V) sorption capacity, potential for large-scale production, and useful magnetic property.
authors: Department of Mechanical and Aerospace Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, U.S.A.
authors: Aamir D
authors: AD
authors: Abid
authors: Masakazu
authors: M
authors: Kanematsu
authors: Thomas M
authors: TM
authors: Young
authors: Ian M
authors: IM
authors: Kennedy
references: Environ Sci Technol. 2010 May 1;44(9):3388-94
references: 20355701
references: Chem Commun (Camb). 2004 Oct 21;(20):2306-7
references: 15489993
references: Science. 2002 Jun 21;296(5576):2145-6
references: 12077388
references: ACS Nano. 2010 Jul 27;4(7):3979-86
references: 20552997
references: Environ Sci Technol. 2011 Jan 15;45(2):561-8
references: 21158435
references: J Aerosol Sci. 2010 Mar 1;41(3):257-265
references: 20228941
references: Environ Sci Technol. 2005 Mar 1;39(5):1291-8
references: 15787369
references: Environ Sci Technol. 2007 Jul 15;41(14):5114-9
references: 17711232
references: Science. 2002 Jun 21;296(5576):2143-5
references: 12077387
references: Lancet. 1988 Feb 20;1(8582):414-5
references: 2893213
references: Environ Sci Technol. 2008 Sep 15;42(18):6949-54
references: 18853814
references: Science. 2006 Nov 10;314(5801):964-7
references: 17095696
references: Environ Sci Technol. 2008 May 15;42(10):3786-90
references: 18546723
references: Environ Sci Technol. 2003 Sep 15;37(18):4182-9
references: 14524451
references: J Hazard Mater. 2007 Mar 22;141(3):575-80
references: 16978766