Arsenate adsorption mechanisms at the allophane - water interface

被引:106
作者
Arai, Y
Sparks, DL
Davis, JA
机构
[1] US Geol Survey, Menlo Pk, CA 94025 USA
[2] Univ Delaware, Dept Plant & Soil Sci, Newark, DE 19717 USA
关键词
D O I
10.1021/es0486770
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
We investigated arsenate (As(V)) reactivity and surface speciation on amorphous aluminosilicate mineral (synthetic allophane) surfaces using batch adsorption experiments, powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The adsorption isotherm experiments indicated that As(V) uptake increased with increasing [As-(V)](o) from 50 to 1000 mu M (i.e., Langmuir type adsorption isotherm) and that the total As adsorption slightly decreased with increasing NaCl concentrations from 0.01 to 0.1 M, Arsenate adsorption was initially (0-10 h) rapid followed by a slow continuum uptake, and the adsorption processes reached the steady state after 720 h. X-ray absorption spectroscopic analyses suggest that As(V) predominantly forms bidentate binuclear surface species on aluminum octahedral structures, and these species are stable up to 11 months. Solubility calculations and powder XRD analyses indicate no evidence of crystalline Al-As(V) precipitates in the experimental systems. Overall, macroscopic and spectroscopic evidence suggest that the As(V) adsorption mechanisms at the allophane-water interface are attributable to ligand exchange reactions between As(V) and surface-coordinated water molecules and hydroxyl and silicate ions, The research findings imply that dissolved tetrahedral oxyanions (e.g., H2PO42- and H2AsO42-) are readily retained on amorphous aluminosilicate minerals in aquifer and soils at near neutral pH. The inner-sphere adsorption mechanisms might be important in controlling dissolved arsenate and phosphate in amorphous aluminosilicate-rich low-temperature geochemical environments.
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页码:2537 / 2544
页数:8
相关论文
共 61 条
[1]   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
[2]   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
[3]   GEOCHEMICAL HETEROGENEITY IN A SAND AND GRAVEL AQUIFER - EFFECT OF SEDIMENT MINERALOGY AND PARTICLE-SIZE ON THE SORPTION OF CHLOROBENZENES [J].
BARBER, LB ;
THURMAN, EM ;
RUNNELLS, DD .
JOURNAL OF CONTAMINANT HYDROLOGY, 1992, 9 (1-2) :35-54
[4]  
Brown G., 1980, Crystal Structures of Clay Minerals and their X-ray Identification, P361, DOI [10.1180/mono-5.6, DOI 10.1180/MONO-5.6]
[5]   Nitrate and colloid transport through coarse Hanford sediments under steady state, variably saturated flow [J].
Cherrey, KD ;
Flury, M ;
Harsh, JB .
WATER RESOURCES RESEARCH, 2003, 39 (06) :SWC41-SWC410
[6]  
CLARK CJ, 1984, CLAY CLAY MINER, V32, P291, DOI 10.1346/CCMN.1984.0320407
[7]   PB2+ AND ZN2+ ADSORPTION BY A NATURAL ALUMINUM-BEARING AND IRON-BEARING SURFACE COATING ON AN AQUIFER SAND [J].
COSTON, JA ;
FULLER, CC ;
DAVIS, JA .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1995, 59 (17) :3535-3547
[8]   ALUMINUM RELEASE RATES FROM SELECTED SPODOSOL BS HORIZONS - EFFECT OF PH AND SOLID-PHASE ALUMINUM POOLS [J].
DAHLGREN, RA ;
WALKER, WJ .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1993, 57 (01) :57-66
[9]   Implications of aqueous silica sorption to iron hydroxide: Mobilization of iron colloids and interference with sorption of arsenate and humic substances [J].
Davis, CC ;
Knocke, WR ;
Edwards, M .
ENVIRONMENTAL SCIENCE & TECHNOLOGY, 2001, 35 (15) :3158-3162
[10]   X-ray absorption spectroscopy study of the effects of pH and ionic strength on Pb(II) sorption to amorphous silica [J].
Elzinga, EJ ;
Sparks, DL .
ENVIRONMENTAL SCIENCE & TECHNOLOGY, 2002, 36 (20) :4352-4357