Mechanism of Arsenic Adsorption on Magnetite Nanoparticles from Water: Thermodynamic and Spectroscopic Studies
Top Cited Papers
- 19 June 2015
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 49 (13), 7726-7734
- https://doi.org/10.1021/acs.est.5b00381
Abstract
Removal of arsenic (As) from water supplies is needed to reduce As exposure through drinking water and food consumption in many regions of the world. Magnetite nanoparticles (MNPs) are promising and novel adsorbents for As removal because of their great adsorption capacity for As and easy separation. This study aimed to investigate the adsorption mechanism of arsenate, As(V), and arsenite, As(III), on MNPs by macroscopic adsorption experiments in combination with thermodynamic calculation and microspectroscopic characterization using synchrotron-radiation-based X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). Adsorption reactions are favorable endothermic processes as evidenced by increased adsorption with increasing temperatures, and high positive enthalpy change. EXAFS spectra suggested predominant formation of bidentate binuclear corner-sharing complexes ((2)C) for As(V), and tridentate hexanuclear corner-sharing ((3)C) complexes for As(III) on MNP surfaces. The macroscopic and microscopic data conclusively identified the formation of inner-sphere complexes between As and MNP surfaces. More intriguingly, XANES and XPS results revealed complex redox transformation of the adsorbed As on MNPs exposed to air: Concomitant with the oxidation of MNPs, the oxidation of As(III) and MNPs was expected, but the observed As(V) reduction was surprising because of the role played by the reactive Fe(II).Keywords
Funding Information
- National Institute of Food and Agriculture (MICL02248)
This publication has 56 references indexed in Scilit:
- New Generation Adsorbents for Water TreatmentChemical Reviews, 2012
- Arsenic Exposure and Toxicology: A Historical PerspectiveToxicological Sciences, 2011
- Self-assembled Fe3O4-layered double hydroxide colloidal nanohybrids with excellent performance for treatment of organic dyes in waterJournal of Materials Chemistry, 2010
- Redox Transformation of Arsenic by Fe(II)-Activated Goethite (α-FeOOH)Environmental Science & Technology, 2009
- Extended X-ray Absorption Fine Structure Analysis of Arsenite and Arsenate Adsorption on MaghemiteEnvironmental Science & Technology, 2008
- The effect of nanocrystalline magnetite size on arsenic removalScience and Technology of Advanced Materials, 2007
- Low-Field Magnetic Separation of Monodisperse Fe 3 O 4 NanocrystalsScience, 2006
- Investigations on the adsorption efficiency of iron oxide coated cement (IOCC) towards As(V)—kinetics, equilibrium and thermodynamic studiesColloids and Surfaces A: Physicochemical and Engineering Aspects, 2006
- A review of the source, behaviour and distribution of arsenic in natural watersApplied Geochemistry, 2002
- Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenateGeochimica et Cosmochimica Acta, 1993