Oxidation–reduction titrations and potentiometric methods provide a convenient experimental means to quantitatively determine compositions of unknown mixtures containing oxidizable/reducible species. Over the past decade, numerous titration methods have appeared in this Journal (1–6) and in standard laboratory manuals (7–10) involving common titrants such as potassium dichromate, iodine, potass...

Chromium in fumes generated in work environments including sites of welding work appears in various and complex states. Determination of chromium speciation in samples is useful for estimating the toxicity of such fumes. In the present study, determination of chromium speciation in chromium fumes prepared using a plasma metal sprayer, which are regarded as a model of actual fumes, was carried o...

Chromium is generated from several industrial processes. It occurs in different oxidation states, but Cr(III) and Cr(VI) are the most common ones. Cr(VI) is a toxic, soluble environmental contaminant. Some bacteria are able to reduce hexavalent chromium to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of considerable interest. An indigenous chromium-reducing bacteria...

The isothermal isotopic exchange reaction of O2 with 16O of chromium(VI) oxide supported on zirconia, alumina, and titania has been investigated with in situ laser Raman spectroscopy. The isotopic exchange reaction is dependent on the support type, the Cr loading, and the reaction temperature. Complete isotopic exchange of chromium(VI) oxide with O2 is difficult to achieve and requires several ...

the problem of removing pollutants from water is an important process and is becoming moreimportant with the increasing of industrial activities. one of the most important environmental problems iswater resources pollution by heavy metals. bioabsorbtion is affordable adsorbents for the removal of heavymetals from aqueous solutions. this study explores the adsorption potential of cr (vi), cd (ii...

B ak o re and N a r a in 1 studied the kinetics of the oxidation of a-hydroxy acids by chromium(VI) and found that addition of Mn(II) decreases the rate of oxidation to one half of that in absence of Mn(II), when the hydrogen ion concentration is in the range 0.1 to 0.4 M. They attributed this to the disproportionation of Cr(IV) by Mn(II) ions. K em p and W a t e r s 2 observed Mn(II) catalysis...

The mutagenicity of sodium dichromate in the Ames test was decreased as a consequence of chromium(VI) reduction by tissue postmitochondrial (S-9 or S-12) fractions from untreated rats with the following rank of efficiency: liver; kidney; and lung. The effects of lung preparations were significantly enhanced following the intratracheal administration of high doses (0.25 mg/kg) of dichromate itse...