Arsenite sorption on troilite (FeS) and pyrite (FeS 2 )

Arsenite sorption on troilite (FeS) and pyrite (FeS 2 ) Arsenic is a toxic metalloid whose mobility and availability are largely controlled by sorption on sulfide minerals in anoxic environments. Accordingly, we investigated reactions of As(III) with iron sulfide (FeS) and pyrite (FeS 2 ) as a function of total arsenic concentration, suspension density, sulfide concentration, pH, and ionic strength. Arsenite partitioned strongly on both FeS and FeS 2 under a range of conditions and conformed to a Langmuir isotherm at low surface coverages; a calculated site density of near 2.6 and 3.7 sites/nm 2 for FeS and FeS 2 , respectively, was obtained. Arsenite sorbed most strongly at elevated pH (>5 to 6). Although solution data suggested the formation of surface precipitates only at elevated solution concentrations, surface precipitates were identified using X-ray absorption spectroscopy (XAS) at all coverages. Sorbed As was coordinated to both sulfur (d(As-S) = 2.35 Å) and iron (d(As-Fe) = 2.40 Å), characteristic of As coordination in arsenopyrite (FeAsS). The absorption edge of sorbed As was also shifted relative to arsenite and orpiment (As 2 S 3 ), revealing As(III) reduction and a complete change in As local structure. Arsenic reduction was accompanied by oxidation of both surface S and Fe(II); the FeAsS-like surface precipitate was also susceptible to oxidation, possibly influencing the stability of As sorbed to sulfide minerals in the environment. Sulfide additions inhibit sorption despite the formation of a sulfide phase, suggesting that precipitation of arsenic sulfide is not occurring. Surface precipitation of As on FeS and FeS 2 supports the observed correlation of arsenic and pyrite and other iron sulfides in anoxic sediments. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Geochimica et Cosmochimica Acta Elsevier

Arsenite sorption on troilite (FeS) and pyrite (FeS 2 )

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Publisher
Elsevier
Copyright
Copyright © 2002 Elsevier Science Ltd
ISSN
0016-7037
eISSN
1872-9533
D.O.I.
10.1016/S0016-7037(02)01170-5
Publisher site
See Article on Publisher Site

Abstract

Arsenic is a toxic metalloid whose mobility and availability are largely controlled by sorption on sulfide minerals in anoxic environments. Accordingly, we investigated reactions of As(III) with iron sulfide (FeS) and pyrite (FeS 2 ) as a function of total arsenic concentration, suspension density, sulfide concentration, pH, and ionic strength. Arsenite partitioned strongly on both FeS and FeS 2 under a range of conditions and conformed to a Langmuir isotherm at low surface coverages; a calculated site density of near 2.6 and 3.7 sites/nm 2 for FeS and FeS 2 , respectively, was obtained. Arsenite sorbed most strongly at elevated pH (>5 to 6). Although solution data suggested the formation of surface precipitates only at elevated solution concentrations, surface precipitates were identified using X-ray absorption spectroscopy (XAS) at all coverages. Sorbed As was coordinated to both sulfur (d(As-S) = 2.35 Å) and iron (d(As-Fe) = 2.40 Å), characteristic of As coordination in arsenopyrite (FeAsS). The absorption edge of sorbed As was also shifted relative to arsenite and orpiment (As 2 S 3 ), revealing As(III) reduction and a complete change in As local structure. Arsenic reduction was accompanied by oxidation of both surface S and Fe(II); the FeAsS-like surface precipitate was also susceptible to oxidation, possibly influencing the stability of As sorbed to sulfide minerals in the environment. Sulfide additions inhibit sorption despite the formation of a sulfide phase, suggesting that precipitation of arsenic sulfide is not occurring. Surface precipitation of As on FeS and FeS 2 supports the observed correlation of arsenic and pyrite and other iron sulfides in anoxic sediments.

Journal

Geochimica et Cosmochimica ActaElsevier

Published: Mar 1, 2003

References

  • Surface charge development on transition metal sulfides
    Bebie, J.; Schoonen, M.A.A.; Fuhrmann, M.; Strongin, D.R.
  • Disulfide disproportionation and CdS formation upon cadmium sorption on FeS 2
    Bostick, B.C.; Fendorf, S.; Fendorf, M.
  • Electrochemical evidence for metal polysulfide complexes
    Chadwell, S.J.; Rickard, D.; Luther, G.W.
  • Arsenic speciation in the environment
    Cullen, W.R.; Reimer, K.J.
  • FT-IR and FT-Raman studies of colloidal ZnS
    Gärd, R.; Sun, Z.-X.; Forsling, W.
  • Surface structural adsorption modeling of competitive binding of oxyanions by metal (hydr)oxides
    Hiemstra, T.; Van Riemsdijk, W.H.
  • Oxidation of arsenopyrite by air and air-saturated distilled water and implications for mechanism of oxidation
    Nesbitt, H.W.; Muir, L.J.; Pratt, A.R.
  • Mechanism of arsenic release to groundwater, Bangladesh and West Bengal
    Nickson, R.T.; McArthur, J.M.; Ravenscroft, P.; Burgess, W.G.; Ahmed, K.M.
  • WinXAS
    Ressler, T.
  • Arsenic chemistry in soils
    Sadiq, M.
  • Arsenic speciation in pyrite and secondary weathering phases
    Savage, K.S.; Tingle, T.N.; O’Day, P.A.; Waychunas, G.A.; Bird, D.K.
  • Diagenetic cycling of arsenic in Amazon shelf sediments
    Sullivan, K.A.; Aller, R.C.
  • Surface states and reactivity of pyrite and marcasite
    Uhlig, I.; Szargan, R.; Nesbitt, H.W.; Laajalehto, K.
  • Using X-ray absorption to probe sulfur oxidation states in complex molecules
    Vairavamurthy, A.

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