File Download

There are no files associated with this item.

  Links for fulltext
     (May Require Subscription)
Supplementary

Article: Oxidation of As(III) by MnO 2 in the absence and presence of Fe(II) under acidic conditions

TitleOxidation of As(III) by MnO 2 in the absence and presence of Fe(II) under acidic conditions
Authors
KeywordsAcidity
Adsorption
Arsenic
Diffusion
Geochemistry
Issue Date2011
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/gca
Citation
Geochimica Et Cosmochimica Acta, 2011, v. 75 n. 2, p. 368-379 How to Cite?
AbstractOxidation of As(III) by natural manganese (hydr)oxides is an important geochemical reaction mediating the transformation of highly concentrated As(III) in the acidic environment such as acid mine drainage (AMD) and industrial As-contaminated wastewater, however, little is known regarding the presence of dissolved Fe(II) on the oxidation process. In this study, oxidation of As(III) in the absence and presence of Fe(II) by MnO 2 under acidic conditions was investigated. Kinetic results showed that the presence of Fe(II) significantly inhibited the removal of As(III) (including oxidation and sorption) by MnO 2 in As(III)-Fe(II) simultaneous oxidation system even at the molar ratio of Fe(II):As(III)=1/64:1, and the inhibitory effects increased with the increasing ratios of Fe(II):As(III). Such an inhibition could be attributed to the formation of Fe(III) compounds covering the surface of MnO 2 and thus preventing the oxidizing sites available to As(III). On the other hand, the produced Fe(III) compounds adsorbed more As(III) and the oxidized As(V) on the MnO 2 surface with an increasing ratio of Fe(II):As(III) as demonstrated in kinetic and XPS results. TEM and EDX results confirmed the formation of Fe compounds around MnO 2 particles or separated in solution in Fe(II) individual oxidation system, Fe(II) pre-treated and simultaneous oxidation processes, and schwertmannite was detected in Fe(II) individual and Fe pre-treated oxidation processes, while a new kind of mineral, probably amorphous FeOHAs or FeAsO 4 particles were detected in Fe(II)-As(III) simultaneous oxidation process. This suggests that the mechanisms are different in Fe pre-treated and simultaneous oxidation processes. In the Fe pre-treated and MnO 2-mediated oxidation pathway, As(III) diffused through a schwertmannite coating formed around MnO 2 particles to be oxidized. The newly formed As(V) was adsorbed onto the schwertmannite coating until its sorption capacity was exceeded. Arsenic(V) then diffused out of the coating and was released into the bulk solution. The diffusion into the schwertmannite coating and the oxidation of As(III) and sorption of both As(V) and As(III) onto the coating contributed to the removal of total As from the solution phase. In the simultaneous oxidation pathway, the competitive oxidation of Fe(II) and As(III) on MnO 2 occurred first, followed by the formation of FeOHAs or FeAsO 4 around MnO 2 particles, and these poorly crystalline particles of FeOHAs and FeAsO 4 remained suspended in the bulk solution to adsorb As(III) and As(V). The present study reveals that the formation of Fe(III) compounds on mineral surfaces play an important role in the sorption and oxidation of As(III) by MnO 2 under acidic conditions in natural environments, and the mechanisms involved in the oxidation of As(III) depend upon how Fe(II) is introduced into the As(III)-MnO 2 system. © 2010 Elsevier Ltd.
Persistent Identifierhttp://hdl.handle.net/10722/139198
ISSN
2015 Impact Factor: 4.315
2015 SCImago Journal Rankings: 3.016
ISI Accession Number ID
Funding AgencyGrant Number
Strategic Research Theme on Sustainable Environment (Sustainable Water)
Faculty of Science of The University of Hong Kong
National Natural Science Foundation of China41003040
Natural Science Foundation of Tianjin10JCYBJC06000
Funding Information:

This work is partially supported by the Strategic Research Theme on Sustainable Environment (Sustainable Water) and the Faculty of Science of The University of Hong Kong (J-DG), and the National Natural Science Foundation of China (No. 41003040) and the Natural Science Foundation of Tianjin (No. 10JCYBJC06000) (XH). We thank experiment assistance from Ms. Jessie Lai, Technical support of TEM analysis from Mr. Frankie Chan (EM unit, HKU), XRD analysis from Ms. Xiao Fu (Earth Sciences Department, HKU), XPS analysis from Mr. Rayman Chan (HKSTP) and BET analysis from Ms. Crystal Cheung (Chemistry Department, HKU), and additional support of Yong Liu and Hai-Tao Ren (Tianjin University). We also greatly thank Prof. Donald Sparks and anonymous reviewers for constructive reviews and insightful comments.

References

 

DC FieldValueLanguage
dc.contributor.authorHan, Xen_HK
dc.contributor.authorLi, YLen_HK
dc.contributor.authorGu, JDen_HK
dc.date.accessioned2011-09-23T05:46:33Z-
dc.date.available2011-09-23T05:46:33Z-
dc.date.issued2011en_HK
dc.identifier.citationGeochimica Et Cosmochimica Acta, 2011, v. 75 n. 2, p. 368-379en_HK
dc.identifier.issn0016-7037en_HK
dc.identifier.urihttp://hdl.handle.net/10722/139198-
dc.description.abstractOxidation of As(III) by natural manganese (hydr)oxides is an important geochemical reaction mediating the transformation of highly concentrated As(III) in the acidic environment such as acid mine drainage (AMD) and industrial As-contaminated wastewater, however, little is known regarding the presence of dissolved Fe(II) on the oxidation process. In this study, oxidation of As(III) in the absence and presence of Fe(II) by MnO 2 under acidic conditions was investigated. Kinetic results showed that the presence of Fe(II) significantly inhibited the removal of As(III) (including oxidation and sorption) by MnO 2 in As(III)-Fe(II) simultaneous oxidation system even at the molar ratio of Fe(II):As(III)=1/64:1, and the inhibitory effects increased with the increasing ratios of Fe(II):As(III). Such an inhibition could be attributed to the formation of Fe(III) compounds covering the surface of MnO 2 and thus preventing the oxidizing sites available to As(III). On the other hand, the produced Fe(III) compounds adsorbed more As(III) and the oxidized As(V) on the MnO 2 surface with an increasing ratio of Fe(II):As(III) as demonstrated in kinetic and XPS results. TEM and EDX results confirmed the formation of Fe compounds around MnO 2 particles or separated in solution in Fe(II) individual oxidation system, Fe(II) pre-treated and simultaneous oxidation processes, and schwertmannite was detected in Fe(II) individual and Fe pre-treated oxidation processes, while a new kind of mineral, probably amorphous FeOHAs or FeAsO 4 particles were detected in Fe(II)-As(III) simultaneous oxidation process. This suggests that the mechanisms are different in Fe pre-treated and simultaneous oxidation processes. In the Fe pre-treated and MnO 2-mediated oxidation pathway, As(III) diffused through a schwertmannite coating formed around MnO 2 particles to be oxidized. The newly formed As(V) was adsorbed onto the schwertmannite coating until its sorption capacity was exceeded. Arsenic(V) then diffused out of the coating and was released into the bulk solution. The diffusion into the schwertmannite coating and the oxidation of As(III) and sorption of both As(V) and As(III) onto the coating contributed to the removal of total As from the solution phase. In the simultaneous oxidation pathway, the competitive oxidation of Fe(II) and As(III) on MnO 2 occurred first, followed by the formation of FeOHAs or FeAsO 4 around MnO 2 particles, and these poorly crystalline particles of FeOHAs and FeAsO 4 remained suspended in the bulk solution to adsorb As(III) and As(V). The present study reveals that the formation of Fe(III) compounds on mineral surfaces play an important role in the sorption and oxidation of As(III) by MnO 2 under acidic conditions in natural environments, and the mechanisms involved in the oxidation of As(III) depend upon how Fe(II) is introduced into the As(III)-MnO 2 system. © 2010 Elsevier Ltd.en_HK
dc.languageengen_US
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/gcaen_HK
dc.relation.ispartofGeochimica et Cosmochimica Actaen_HK
dc.subjectAcidity-
dc.subjectAdsorption-
dc.subjectArsenic-
dc.subjectDiffusion-
dc.subjectGeochemistry-
dc.titleOxidation of As(III) by MnO 2 in the absence and presence of Fe(II) under acidic conditionsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0016-7037&volume=75&issue=2&spage=368&epage=379&date=2011&atitle=Oxidation+of+As(III)+by+MnO2+in+the+absence+and+presence+of+Fe(II)+under+acidic+conditions-
dc.identifier.emailLi, YL: yiliang@hku.hken_HK
dc.identifier.emailGu, JD: jdgu@hkucc.hku.hken_HK
dc.identifier.authorityLi, YL=rp01354en_HK
dc.identifier.authorityGu, JD=rp00701en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.gca.2010.10.010en_HK
dc.identifier.scopuseid_2-s2.0-78650204462en_HK
dc.identifier.hkuros194103en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-78650204462&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume75en_HK
dc.identifier.issue2en_HK
dc.identifier.spage368en_HK
dc.identifier.epage379en_HK
dc.identifier.eissn0016-7037-
dc.identifier.isiWOS:000286349600003-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridHan, X=37110924600en_HK
dc.identifier.scopusauthoridLi, YL=27171876700en_HK
dc.identifier.scopusauthoridGu, JD=7403129601en_HK
dc.identifier.citeulike8133486-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats