Surface complexation of sulfate by hematite surfaces: FTIR and STM observations

被引:101
作者
Eggleston, CM [1 ]
Hug, S
Stumm, W
Sulzberger, B
Afonso, MD
机构
[1] Univ Wyoming, Dept Geol & Geophys, Laramie, WY 82071 USA
[2] Swiss Fed Inst Technol, Fed Inst Environm Sci & Technol, CH-8600 Dubendorf, Switzerland
[3] Univ Buenos Aires, Fac Ciencias Exactas & Nat, Dept Quim Inorgan Analit & Quim Fis, RA-1428 Buenos Aires, DF, Argentina
基金
美国国家科学基金会;
关键词
D O I
10.1016/S0016-7037(97)00372-4
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
Sulfate adsorbed to hematite surfaces from aqueous solution is examined using Fourier transform infrared (FTIR) spectroscopy and scanning tunneling microscopy (STM). FTIR was carried out using an Attenuated Total Reflectance (ATR) element coated with a fixed layer of hematite particles; this configuration allowed in situ variation of pH and sulfate concentration. The FTIR results are consistent with an inner-sphere monodentate surface complex. On dried samples, sulfate may form bidentate or possibly monodentate bisulfate complexes. STM was applied to samples that were removed from solution and imaged in air, conditions corresponding to those of the dried samples in FTIR. The images show mobile adsorbates whose lifetimes were greater than 5 ms and less than 240 ms, times that bracket the average lifetimes of aqueous FeSO4+ complexes (similar to 50 ms). In addition, the images show pairs of bumps, in agreement with STM images of bisulfate adsorbed on Pt(lll) electrode surfaces (Funtikov et al., 1995). Although the STM images do not provide chemical identification, they are consistent with imaging of adsorbed inner-sphere sulfate (STM is incapable of seeing outer-sphere adsorbates). Our results suggest that categorization of adsorbates into inner-sphere and outer-sphere on the basis of macroscopic adsorption information is perhaps oversimplistic. Instead, a spectrum of intermediate behaviors is likely. Adsorbates classed (macroscopically) as outer-sphere may be those for which a relatively small proportion of adsorbates are in inner-sphere complexes at any given time. Copyright (C)1998 Elsevier Science Ltd.
引用
收藏
页码:585 / 593
页数:9
相关论文
共 48 条
[1]   Effects of simple organic acids on sorption of Cu2+ and Ca2+ on goethite [J].
Ali, MA ;
Dzombak, DA .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1996, 60 (02) :291-304
[2]  
Andermann M, 1988, SEMICONDUCTOR ELECTR, V55, P147
[3]  
[Anonymous], REV MINERAL
[4]   Outer-sphere Pb(II) adsorbed at specific surface sites on single crystal alpha-alumina [J].
Bargar, JR ;
Towle, SN ;
Brown, GE ;
Parks, GA .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1996, 60 (18) :3541-3547
[5]  
Becker U, 1996, AM MINERAL, V81, P1301
[6]   THE REACTIVITY OF FE(III) (HYDR)OXIDES - EFFECTS OF LIGANDS IN INHIBITING THE DISSOLUTION [J].
BONDIETTI, G ;
SINNIGER, J ;
STUMM, W .
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 1993, 79 (2-3) :157-167
[7]   A TEMPERATURE-JUMP STUDY OF KINETICS OF FORMATION OF MONOSULFATO COMPLEX OF IRON(3) [J].
CAVASINO, FP .
JOURNAL OF PHYSICAL CHEMISTRY, 1968, 72 (04) :1378-&
[8]   SURFACE-IONIZATION AND COMPLEXATION AT THE OXIDE-WATER INTERFACE .3. ADSORPTION OF ANIONS [J].
DAVIS, JA ;
LECKIE, JO .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 1980, 74 (01) :32-43
[9]   SCANNING-TUNNELING-MICROSCOPY STUDY OF THE SURFACE-DIFFUSION OF SULFUR ON RE(0001) [J].
DUNPHY, JC ;
SAUTET, P ;
OGLETREE, DF ;
DABBOUSI, O ;
SALMERON, MB .
PHYSICAL REVIEW B, 1993, 47 (04) :2320-2328
[10]  
Dzombak D.A., 1990, SURFACE COMPLEXATION