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Titolo:
OXIDATION OF DIMETHYLSELENIDE BY DELTA-MNO2 - OXIDATION-PRODUCT AND FACTORS AFFECTING OXIDATION RATE
Autore:
WANG BW; BURAU RG;
Indirizzi:
US GEOL SURVEY,DIV WATER RESOURCES,2800 COTTAGE WAY,ROOM 2233 SACRAMENTO CA 95825 UNIV CALIF DAVIS,DEPT LAND AIR & WATER RESOURCES DAVIS CA 95616
Titolo Testata:
Environmental science & technology
fascicolo: 6, volume: 29, anno: 1995,
pagine: 1504 - 1510
SICI:
0013-936X(1995)29:6<1504:OODBD->2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
MANGANESE(IV) OXIDES; SELENIUM; SEDIMENTS; BIOMETHYLATION; DISSOLUTION; SPECIATION; REDUCTION; ORGANICS; MARINE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
43
Recensione:
Indirizzi per estratti:
Citazione:
B.W. Wang e R.G. Burau, "OXIDATION OF DIMETHYLSELENIDE BY DELTA-MNO2 - OXIDATION-PRODUCT AND FACTORS AFFECTING OXIDATION RATE", Environmental science & technology, 29(6), 1995, pp. 1504-1510

Abstract

Volatile dimethylselenide (DMSe) was transformed to a nonvolatile Se compound in a delta-MnO2 suspension. The nonvolatile product was a single compound identified as dimethylselenoxide based on its mass spectra pattern. After 24 h, 100% of the DMSe added to a delta-MnO2 suspension was converted to nonpurgable Se as opposed to 20%, 18%, and 4% conversion for chromate, permanganate, and the filtrate from the suspension, respectively. Manganese was found in solution after reaction. Theseresults imply that the reaction between manganese oxide and DMSe was a heterogeneous redox reaction involving solid phase delta-MnO2 and solution phase DMSe. Oxidation of DMSe to dimethylselenoxide [OSe(CH3)(2)] by a delta-MnO2 suspension appears to be first order with respect to delta-MnO2, to DMSe, and to hydrogen ion with an overall rate law ofd[OSe(CH3)(2)]/dt = 95 M(-2) min(-1) [MnO2](1)[DMSe](1)[H+](1) for the MnO2 concentration range of 0.89 x 10(-3) - 2.46 x 10(-3) M, the DMSe concentration range of 3.9 x 10(-7) - 15.5 x 10(-7) M Se, and a hydrogen ion concentation range of 7.4 x 10(-6) - 9.5 x 10(-8) M. A general surface site adsorption model is consistent with this rate equation if the uncharged \ OMnOH is the surface adsorption site. DMSe acts as a Lewis base, and the manganese oxide surface acts as a Lewis acid. DMSe adsorption to \ OMnOH can be viewed as a Lewis acid/base complex between the largely p orbitals of the DMSe lone pair and the unoccupied e(g) orbitals on manganese oxide. For such a complex, frontier molecular orbital theory predicts electron transfer to occur via an inner-sphere complex between the DMSe and the manganese oxide.

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Documento generato il 03/12/20 alle ore 14:24:27