کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
612036 880690 2007 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Investigation of pyrite oxidation by hexavalent chromium: Solution species and surface chemistry
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی شیمی کلوئیدی و سطحی
پیش نمایش صفحه اول مقاله
Investigation of pyrite oxidation by hexavalent chromium: Solution species and surface chemistry
چکیده انگلیسی

Pyrite oxidation processes by aqueous Cr(VI) were investigated at 25 °C under an argon atmosphere. Synthetic pyrite suspensions (6 g L−1) were reacted for 20 h with a range of Cr(VI) solutions from 0 to 700 μM and at pH 2–12. The main objective of this work was to investigate the reaction mechanisms by emphasizing the role of sulfur species. Aqueous chemical processes were well illustrated in acidic media where significant amounts of sulfate and iron species were determined. Sulfate anions are the final stable sulfur species involved in the reaction pathway. Experiments showing complete Cr(VI) removal from solution displayed ratios [S(VI)]/[Fe]tot < 2, probably due to a deficit in aqueous sulfur species. Experiments showing incomplete Cr(VI) removal displayed ratios [Cr(VI)]removed/[S(VI)] close to 1.5. This ratio was found to be consistent with the formation of thiosulfate (S2O2−3). Thiosulfate ions disproportionated into elemental sulfur S(0) and tetrathionate ions (S4O2−6) that were finally oxidized to sulfate anions under acidic conditions. The distribution of the oxidation state of sulfur atoms at the pyrite surface determined by XPS was additional evidence for the multistep sulfur oxidation process. The presence of elemental sulfur in the S(2p) spectra correlated well with the disproportion of thiosulfate under acidic conditions.

Pyrite oxidation by aqueous Cr(VI) is investigated by using XPS and solution analyses. Distribution of the oxidation state of sulfur atoms at the reacted surface is illustrated in the S(2p) spectrum.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Colloid and Interface Science - Volume 316, Issue 2, 15 December 2007, Pages 531–540
نویسندگان
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