Simultaneous inner- and outer-sphere arsenate adsorption on corundum and hematite

被引:232
作者
Catalano, Jeffrey G. [1 ]
Park, Changyong [1 ]
Fenter, Paul [1 ]
Zhang, Zhan [2 ]
机构
[1] Argonne Natl Lab, Div Chem, Argonne, IL 60439 USA
[2] Washington Univ, Adv Photon Source, St Louis, MO 63141 USA
关键词
D O I
10.1016/j.gca.2008.02.013
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
The ability to predict the fate and transport of arsenic in aquatic environments, its impact on water quality and human health, and the performance and cost-effectiveness of water treatment systems relies on understanding how it interacts with solid surfaces. In situ resonant surface X-ray scattering measurements of arsenate adsorption at pH 5 in 0.01 M NaCl on corundum and hematite (012) surfaces demonstrate that arsenate surface complexation is unexpectedly bimodal, adsorbing simultaneously as inner- and outer-sphere species. In addition, this bimodal behavior is found to be independent of the total arsenate solution concentration, and thus surface coverage, over the range of 10(-6) to 10(-3) M. Alternative mechanisms to produce the observed As distributions, such as arsenate dimerization or surface precipitation of an aluminum or ferric arsenate, are inconsistent with the experimentally-determined total and As-specific density profiles. Based on the location of the outersphere arsenate in relation to the surfaces studied, possible binding mechanisms include electrostatic attraction, hydrogen bonding to surface oxygen functional group, and configurational stabilization by interfacial water. Although the observation of outer-sphere arsenate surface complexes on a metal oxide surface is unprecedented, it is unclear if such species were absent in previous molecular-scale studies, as it is difficult for methods commonly used to investigate the mechanisms of arsenate adsorption to conclusively identify or rule out the presence of outer-sphere species when inner-sphere species are also present. (c) 2008 Elsevier Ltd. All rights reserved.
引用
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页码:1986 / 2004
页数:19
相关论文
共 114 条
[1]  
ALLISON J.D., 1991, MINTEQA2 PRODEFA2 GE
[2]  
[Anonymous], REV MINERAL
[3]   Effects of pH and ionic strength on the adsorption of phosphate and arsenate at the goethite-water interface [J].
Antelo, J ;
Avena, M ;
Fiol, S ;
López, R ;
Arce, F .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 2005, 285 (02) :476-486
[4]   Residence time effects on arsenate surface speciation at the aluminum oxide-water interface [J].
Arai, Y ;
Sparks, DL .
SOIL SCIENCE, 2002, 167 (05) :303-314
[5]   Arsenate adsorption mechanisms at the allophane - water interface [J].
Arai, Y ;
Sparks, DL ;
Davis, JA .
ENVIRONMENTAL SCIENCE & TECHNOLOGY, 2005, 39 (08) :2537-2544
[6]   X-ray absorption spectroscopic investigation of arsenite and arsenate adsorption at the aluminum oxide-water interface [J].
Arai, Y ;
Elzinga, EJ ;
Sparks, DL .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 2001, 235 (01) :80-88
[7]   Effects of dissolved carbonate on arsenate adsorption and surface speciation at the hematite-water interface [J].
Arai, Y ;
Sparks, DL ;
Davis, JA .
ENVIRONMENTAL SCIENCE & TECHNOLOGY, 2004, 38 (03) :817-824
[8]   Arsenic speciation and reactivity in poultry litter [J].
Arai, Y ;
Lanzirotti, A ;
Sutton, S ;
Davis, JA ;
Sparks, DL .
ENVIRONMENTAL SCIENCE & TECHNOLOGY, 2003, 37 (18) :4083-4090
[9]   Uranyl adsorption and surface speciation at the imogolite-water interface: Self-consistent spectroscopic and surface complexation models [J].
Arai, Yuji ;
McBeath, M. ;
Bargar, J. R. ;
Joye, J. ;
Davis, J. A. .
GEOCHIMICA ET COSMOCHIMICA ACTA, 2006, 70 (10) :2492-2509
[10]  
Bethke C., 2002, GEOCHEMISTS WORKBENC