Showing papers on "Sodium dichromate published in 2011"
TL;DR: Overall, the data suggest that Cr(VI) in drinking water can induce oxidative stress, villous cytotoxicity, and crypt hyperplasia in the mouse intestine and may underlie the MOA of intestinal carcinogenesis in mice.
76 citations
TL;DR: Transcriptional changes in response to genotoxicant exposure proved more sensitive than measurement of DNA strand breaks by the Comet assay and the extensive differences in transcription between adults and neonates emphasized the importance of life stage in toxicant testing with Daphnia.
32 citations
Patent•
20 Apr 2011
TL;DR: In this article, a method for recycling vanadium pentoxide and sodium dichromate, which utilizes the discharged wastes, i.e., vanadium-containing and chromium-calcium-containing slag in the process for producing sodium dichrome as raw materials.
Abstract: The invention discloses a method for recycling vanadium pentoxide and sodium dichromate, which utilizes the discharged wastes, i.e. vanadium-containing and chromium-calcium-containing slag in the process for producing sodium dichromate as raw materials. The method comprises the following steps: pulping the raw materials by using water and adding pure alkali into the mixture; dissolving out pentavalent vanadium and hexavalent chromium in the slag; filtering calcium carbonate residues; acidifying an alkali solution by using sulphuric acid; keeping the temperature and curing; filtering and precipitating; enabling the acid liquid enriched in hexavalent chromium to enter the procedure for producing the sodium dichromate to produce the sodium dichromate; heating and dissolving sodium polyoxovanadate by using a sodium hydroxide solution and regulating the pH value; filtering and removing impurities; adding sulphuric acid into a rich vanadium liquid to acidify until the pH value is between about 4 and 5; adding an ammonium salt; and regulating the pH value to 2-2.5 by using the sulphuric acid; crystallizing the poly-vanadium acid ammonium to precipitate under the condition of heating and stirring; and filtering, washing and baking to prepare the qualified finished product of vanadium pentoxide. The method can be used for realizing the cleaning production in the chromium salt industry.
13 citations
Patent•
26 Jan 2011
TL;DR: In this article, a method for preparing sodium bichromate dihydrate (Na2Cr2O7.2H2O) by using an ion-membrane electrolytic method is presented.
Abstract: The invention provides a method for preparing sodium bichromate dihydrate (Na2Cr2O7.2H2O) by using an ion-membrane electrolytic method. The method is as follows: a one-membrane two-room electrolytic cell assembly is formed by using a cation-exchange membrane, a negative electrode and a positive electrode; sodium chromate alkali solution is introduced into an anode chamber. Dilute sodium hydroxidesolution is introduced into a cathode chamber; after direct current is connected, negative ions and positive ions respectively move to the anode chamber and the cathode chamber under the action of anelectric field; the positive ions enters into the cathode chamber by a positive ion membrane, thus obtaining alkali liquor in the cathode chamber; sodium acid chromate solution is obtained in the anode chamber; simultaneously, the negative electrode and the positive respectively output hydrogen and oxygen; sodium bichromate dihydrate products are dissolved out by evaporating and cooling off the sodium acid chromate solution. The Sodium bichromate dihydrate products prepared by the method has high purity; the utilization rate of the raw materials is close to 100%; byproduct sodium hydroxide has high economic value; no waste materials containing chromium are recycled or discharged in the production process; therefore, the method is safe and environment friendly.
4 citations
Patent•
30 Mar 2011
TL;DR: In this article, a clean method for preparing low-sulfur chromium oxide green is described, in which the chromium salt is taken as a raw material and a reducing gas is used as a reducing agent; and the method comprises the following steps of: performing reaction on the Chromium salt and the reducing gas at the temperature of between 300 and 800 DEG C for 0.5 to 5 hours; cooling, washing the reaction mixture with water, filtering, and drying to obtain an intermediate product; performing ball milling on the intermediate product at a rotating speed of
Abstract: The invention discloses a clean method for preparing low-sulfur chromium oxide green. The chromium salt is taken as a raw material and a reducing gas is taken as a reducing agent; and the method comprises the following steps of: performing reaction on the chromium salt and the reducing gas at the temperature of between 300 and 800 DEG C for 0.5 to 5 hours; cooling, washing the reaction mixture with water, filtering, and drying to obtain an intermediate product; performing ball milling on the intermediate product at a rotating speed of 0 to 500rpm/min for 0 to 5 hours; hydrothermally leaching the ball milling product at the temperature of between 100 and 250 DEG C for 0 to 30 hours, washing, filtering and drying to obtain a leacheate; and calcining the leacheate at the temperature of between 600 and 1,300 DEG C in protective atmosphere to obtain the low-sulfur chromium oxide green and a byproduct of chromium-free sodium hydroxide. The chromium salt is sodium dichromate or sodium dichromate; and the reducing gas is hydrogen, natural gas, ammonia gas, coal gas or a mixture thereof.
3 citations
TL;DR: In this article, a passivator consisting of phytic acid, hydrogen peroxide, boric acid and polyethylene glycol was optimized by orthogonal experiment.
Abstract: Passivator components of phytic acid, hydrogen peroxide, boric acid and polyethylene glycol was optimized by orthogonal experiment. Corrosion resistance of passivation film of brass-strip was invertigated by salt spraying, weight loss and electrochemical test. The results show that the optimization passivator consists of phytic acid (50% mass fraction) 8ml/L, hydrogen peroxide (mass fraction 30%) 30ml/L, boric acid 5g/L, polyethylene glycol 15ml/L and additive 4g/L. Corrosion current density and corrosion rate of the brass-strip specimens coated by rich-phytic acid passivator are similar to that treated by traditional sodium dichromate passivator, the characteristic of anti-tarnish slightly better than that coated by sodium dichromate passivator. The feature of rich-phytic acid passivator is environmental protection.
3 citations
TL;DR: In this article, the reaction conditions were optimized for 2-methylnaphthalene oxidation with sodium dichromate in aqueous sulfuric acid in the presence of fat-soluble vitamin K3.
Abstract: The reaction conditions were optimized for 2-methylnaphthalene oxidation to 2-methyl-1,4-naphthoquinone (fat-soluble vitamin K3) with sodium dichromate in aqueous sulfuric acid.
2 citations
Patent•
17 Aug 2011
TL;DR: In this paper, a method for reducing trace element lead in sodium dichromate and chromic anhydride products was proposed, which includes the steps as follows: taking sodium chromate neutral solution in the production of calcium-free roasted sodium dichrome; adding lead acetate or lead seed crystal which accounts for 0.02%-0.1% sodium chromates neutral solution until the lead content in the solution reaches 300ppm-500ppm; adjusting the pH value to 8-10 by sodium hydroxide solution with mass percent concentration of 30%; adding a heavy
Abstract: The invention discloses a method for reducing trace element lead in sodium dichromate and chromic anhydride products. The method includes the steps as follows: taking sodium chromate neutral solution in the production of calcium-free roasted sodium dichromate; adding lead acetate or lead seed crystal which accounts for 0.02%-0.1% sodium chromate neutral solution in mass until the lead content in the solution reaches 300ppm-500ppm; adjusting the pH value to 8-10 by sodium hydroxide solution with mass percent concentration of 30%; adding a heavy metal precipitation flocculant; and reducing the lead content in the sodium chromate neutral solution below 2ppm after the processes of heat insulation, aging, filtration and the like, so as to achieve the purpose of reducing the lead content in the sodium dichromate and the chromic anhydride products. Lead flocculant precipitates are generated, and the lead flocculant precipitates can serve as lead seed crystals to use continuously after being washed by water and treated with hydrochloric acid.
1 citations
Patent•
20 Apr 2011
TL;DR: In this article, a method for preparing sodium dichromate from potassium chromate by taking barium chromate as an intermediate is presented. But the method is not suitable for high temperature and humidity conditions.
Abstract: The invention relates to a method for preparing sodium dichromate from potassium chromate by taking barium chromate as an intermediate. The method comprises the following steps: 1) mixing K2CrO4 with BaO at molar ratio of 1:(0.5-2) to obtain BaCrO4 sediment and a KOH solution, and then carrying out solid-liquid separation; 2) recycling the KOH solution obtained in step 1); 3) mixing the obtained BaCrO4 in step 1) and sodium salt at ratio of 1:(0.5-2), stirring and adjusting the pH value to 1-7 to obtain sodium salt sediment and a Na2Cr2O7 solution, then carrying out solid-liquid separation; 4) roasting the sodium salt sediment obtained in the step 3) to obtain BaO, returning the BaO to the step 1) for recycling; and 5) evaporating the Na2Cr2O7 obtained in the step 3) to obtain a Na2Cr2O7 concentrated solution and crystallizing to obtain Na2Cr2O7 crystal and mother liquor, and returning the mother liquor to the step 3) for recycling. The method provided by the invention has the advantages that the K2CrO4 product is taken as a raw material, and the conversion from potassium chromate products to the sodium dichromate products is realized by controlling conditions; the conversion conditions are mild; operability is strong; and requirements on devices are simple.
1 citations
Patent•
04 May 2011
TL;DR: In this article, an efficient multifunctional descaling agent, which is prepared by mixing hydrogen fluoride, sodium dichromate, methanol, urea and 46 percent industrial nitric acid, is presented.
Abstract: The invention discloses an efficient multifunctional descaling agent, which is prepared by mixing hydrogen fluoride, sodium dichromate, methanol, urea and 46 percent industrial nitric acid. The descaling agent has low production cost and good descaling effect.
1 citations