Showing papers on "Sodium dichromate published in 2006"

Oral chromium(VI) does not affect the frequency of micronuclei in hematopoietic cells of adult mice and of transplacentally exposed fetuses.

Abstract: Chromium(VI) compounds are genotoxic in a variety of cellular systems. Their potential carcinogenicity is affected by toxicokinetic patterns restricting bioavailability to certain targets, and by metabolic pathways affecting interaction of chromate-derived reactive species with DNA. Epidemiological data indicate that chromium(VI) can be carcinogenic to the human respiratory tract following inhalation at doses that are only achieved in certain occupational settings. However, concern has been raised that adverse effects may also result from oral intake. In order to further explore this issue, we performed studies in BDF1 and Swiss mice of both genders and various age. Sodium dichromate dihydrate and potassium dichromate were administered either with the drinking water, up to a concentration of 500 mg chromium(VI)/l for up to 210 consecutive days, or in a single intragastric dose of 17.7 mg/kg body weight. Under these conditions, no increase of the micronucleus frequency was observed in either bone marrow or peripheral blood erythrocytes. Conversely, the same compounds induced a clastogenic damage following intraperitoneal injection, which by-passes detoxification mechanisms. In addition, due to the hypothesis that susceptibility may be increased during the period of embryogenesis, we treated pregnant mice, up to a concentration of 10mg chromium(VI)/l drinking water. There was no effect on the numbers of fetuses/dam and on body weight of fetuses. Again, no toxic or genotoxic effect was observed either in bone marrow of pregnant mice or in liver and peripheral blood of their fetuses. Thus, even at doses that largely exceed drinking water standards (up to 10,000 times) or by massive intragastric administration, chromium(VI) is not genotoxic to hematopoietic cells of either adult mice or transplacentally exposed fetuses. These conclusions are consistent with the poor toxicity and lack of carcinogenicity of oral chromium(VI), and are mechanistically explained by the high efficiency of chromium(VI) detoxification processes in the gastrointestinal tract.

Variation of cell voltage with reaction time in electrochemical synthesis process of sodium dichromate

Abstract: To address the problems existing in the traditional production technique of sodium dichromate, a new green technology of producing sodium dichromate with an electrochemical synthesis method was studied. Using a self-made electrosynthesis reactor of pure titanium and stainless steel, with a multiple-unit metal oxides combination anode, a cathode of stainless steel, and a reinforcing combination cation exchange membrane with perfluorosulfonic and perfluorocarboxylic polymers, experiments were carried out on the direct electrochemical synthesis of sodium dichromate from sodium chromate. From the experimental results and electrochemical reaction principles, it was shown that the electrochemical synthesis reaction process of sodium dichromate may be quantitatively determined from the variation of the cell voltage measured macroscopically with reaction time. Cell voltages were experimentally measured at different initial sodium chromate concentrations in the anolyte, and the dependence of the cell voltage on reaction time was discussed. The mathematical model of the variation of cell voltage with reaction time and the change rate equation of cell voltage were established, and satisfactorily formulated the change law of cell voltage in the electrochemical synthesis process of sodium dichromate.

Process for preparing vitamin K3 by extraction method

Abstract: The invention relates to a process for preparing vitamin K3 through extraction method, which consists of using beta-methylnaphthalene, sodium dichromate, sulfuric acid and organic solvent as principal raw materials, using surface active agent as the catalyst, carrying out oxidation reaction under mild condition, finally conducting abstraction and addition. The invention is characterized in that, an extraction method is employed to extract 2-methyl-1,4-naphthoquinone into the organic solvent, thus inorganic foreign matter can be removed.

Corrosion inhibitors in polyurea coatings

Abstract: Durable elastomeric polyurea coatings can be applied to metal surfaces subjected to impacts and environmental corrosion. Corrosion resistance of the coatings, especially on magnesium alloy surfaces, is improved by incorporation of particulate inhibitor additives in the liquid polyurea precursor coating material. Examples of inhibitors include potassium dichromate, sodium dichromate, potassium permanganate, vanadium pentoxide, phosphorus anhydride, cerium oxide, lanthanum oxide, calcium oxide and sodium oxide.

Shaken Not Stirred: Oxidation of Alcohols with Sodium Dichromate.

Abstract: Efficient and selective oxidation of primary alcohols to the corresponding aldehydes with sodium dichromate at room temperature under solvent-free conditions by shaking is described. This new procedure can also successfully oxidise secondary alcohols.