Kinetics of Arsenopyrite Oxidative Dissolution by Oxygen

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dc.contributor.advisor Burbey, Thomas J. en_US
dc.contributor.advisor Rimstidt, J. Donald en_US
dc.contributor.advisor Schreiber, Madeline en_US
dc.contributor.author Walker, Forest P. en_US
dc.date.accessioned 2011-08-06T16:01:24Z
dc.date.available 2011-08-06T16:01:24Z
dc.date.issued 2004-04-20 en_US
dc.identifier.other etd-04212004-201854 en_US
dc.identifier.uri http://hdl.handle.net/10919/9881
dc.description.abstract The objective of this study is to use a mixed flow reactor system to determine the dissolution rate and infer potential mechanisms of arsenopyrite (FeAsS) oxidation by dissolved oxygen at 25°C and circumneutral pH. Release rates for iron, arsenic and sulfur are calculated for a variety of initial dissolved oxygen (DO) concentrations. Results indicate that the rate of arsenopyrite oxidation, represented by the rate law r = A(6.76 x 10-11) where the rate, r, is in mol/s and surface area, A, is in m2, is not significantly dependent on DO concentration. Arsenic and sulfur are released in a 1:1 molar ratio while iron is released more slowly due to precipitation of iron oxyhydroxides. Our results suggest that the rate determining step in arsenopyrite oxidation is determined by the attachment of oxygen at the anodic site in the mineral, and not the transfer of electrons from the cathodic site to oxygen, as is suggested for other sulfide minerals such as pyrite. Previous work on FeAsS oxidation has been limited to low pH conditions with ferric iron as the oxidant. However, not all arsenopyrite weathering occurs exclusively in acidic environments. For example, at an abandoned arsenopyrite mine in Virginia, the pH of ground and surface waters is consistently between 4 and 7. Results of this study provide important insight to arsenic mobilization processes and rates, at field-relevant conditions, consequently aiding in the effort to understand arsenic release and retention in the environment. en_US
dc.format.medium ETD en_US
dc.publisher Virginia Tech en_US
dc.relation.haspart Thesis_front.pdf en_US
dc.relation.haspart Title_page_abstract.pdf en_US
dc.relation.haspart Thesis_body_back.pdf en_US
dc.rights The authors of the theses and dissertations are the copyright owners. Virginia Tech's Digital Library and Archives has their permission to store and provide access to these works. en_US
dc.source.uri http://scholar.lib.vt.edu/theses/available/etd-04212004-201854 en_US
dc.subject arsenopyrite en_US
dc.subject arsenic en_US
dc.subject oxidation en_US
dc.title Kinetics of Arsenopyrite Oxidative Dissolution by Oxygen en_US
dc.type Thesis en_US
dc.contributor.department Geosciences en_US
dc.description.degree MS en_US

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