کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4416778 1307798 2006 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Adsorption of molybdate and tetrathiomolybdate onto pyrite and goethite: Effect of pH and competitive anions
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم محیط زیست شیمی زیست محیطی
پیش نمایش صفحه اول مقاله
Adsorption of molybdate and tetrathiomolybdate onto pyrite and goethite: Effect of pH and competitive anions
چکیده انگلیسی

The adsorption of two major molybdenum (Mo) species, molybdate (MoO42-) and tetrathiomolybdate (MoS42-) onto two main iron minerals pyrite (FeS2) and goethite (FeOOH) is addressed to elucidate the possible mechanisms of molybdenum immobilization in anoxic sediments. Suspensions of MoS42- (or MoO42-) and goethite (or pyrite) in 0.1 M NaCl solution were equilibrated under anoxic conditions at 25 °C in the pH range from 3 to 10. The competitive effects of sulfate, phosphate, and silicate on the adsorption of MoO42- and MoS42- by pyrite and goethite are also addressed. Adsorption of MoO42- and MoS42- on pyrite and goethite is in general well described by a Langmuir model at low pH; the extent of sorption is a function of pH and the surface loading. Maximum sorption is observed in the acidic pH range (pH < 5) at low surface loading. The adsorption of molybdenum (μmol g−1) depends upon Mo species and on the type of iron mineral following the order: MoS42-–goethite>MoO42-–goethite>MoS42-–pyrite>MoO42-–pyrite. Phosphate appears to compete strongly with MoO42- and MoS42- for the sorption sites of pyrite and goethite. The strength of the phosphate competitive effect follows the sequence of MoO42-–goethite∼MoO42-–pyrite>MoS42-–pyrite>MoS42-–goethite. Silicate and sulfate have a negligible effect on the sorption of MoO42- and MoS42-. The preferred adsorption by iron mineral of MoS42-, as well as its behavior in the presence of competitive anions suggests that tetrathiomolybdate species may be an ultimate reservoir and may control Mo enrichment in the sediments.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemosphere - Volume 62, Issue 10, March 2006, Pages 1726–1735
نویسندگان
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