Sodium dichromate

About: Sodium dichromate is a research topic. Over the lifetime, 421 publications have been published within this topic receiving 6202 citations. The topic is also known as: Disodium salt & sodium bichromate.

Novel Method for Producing Chromic Oxide without Hexavalent Chromium Pollution by Acid Leaching

Abstract: Chromic oxide (Cr2O3) is one of the most important chromic salts and is widely used in industrial applications. Traditionally, Cr2O3 is prepared from chromium trioxide (CrO3) or sodium dichromate (Na2Cr2O7), both of which are manufactured from chromite ore. However, traditional manufacturing processes are time-consuming, inefficient, and energy-consuming, and they can catheuse severe environmental pollution by discharging large quantities of solid residues containing Cr in the form of Cr(VI) compounds. These compounds are also harmful to human health. Therefore, developing an environmentally friendly production process is of great concern to the chromic oxide industry. In this study, a new method for producing Cr2O3 without hexavalent chromium pollution was investigated. In this novel process, 97% of the total Cr—in the form of chromium sulfate (Cr2(SO4)3)—and Fe are leached from ferrochrome alloy using sulfuric acid. The concentration of Fe in the Cr2(SO4)3 solution can be reduced to 2 mg/L after precipitating with oxalic acid and extracting with di (2-ethylhexyl) phosphate. Cr2O3 is then produced by precipitating Cr from the Cr2(SO4)3 solution with sodium hydroxide, followed by calcination of the precipitated Cr(OH)3 at 500°C. Using this method, Cr2O3 with a purity of up to 99.3% was obtained in this study. Throughout the process, Cr existed only in the form of Cr(III); thus, the pollution caused by hexavalent Cr was eliminated, and environmentally friendly production of Cr2O3 was achieved.

Producing Cr 2 O 3 nanooxide from chromite concentrates

Abstract: High-purity (99.9+%) nanosize Cr2O3 was produced from chromite concentrates. Sodium dichromate was produced from an alkaline melt of chromite ore and then nanosize Cr2O3 was obtained by reaction between sodium dichromate and sulphur. Nanooxides were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. The size of particles was 50–148 nm. The nanoparticles show a loosely agglomerated structure. The presented method is simple and economical.

Long-acting glassware detergent

Abstract: The invention discloses a long-acting glassware detergent, which is prepared from the following raw materials in parts by weight: 4-9 parts of 75% ethanol, 5-10 parts of 30% hydrochloric acid solution, 2-7 parts of sodium sulfate, 4-10 parts of sodium percarbonate, 1-5 parts of sodium stearate, 3-10 parts of sodium dichromate dihydrate, 4-10 parts of phosphoric acid, 4-10 parts of sodium cumenesulfonate, 2-7 parts of aloe, 4-10 parts of sodium gluconate, 1-3 parts of fresh ginger, 4-9 parts of sodium alkyl sulfonate and 45 parts of deionized water The long-acting glassware detergent has the beneficial effects that the detergent is good in cleaning effect, long in acting time, free of stimulus to skin, safe and nontoxic

Synthesis of Oxidized Derivatives of 10‐Deuterobenzo[A]Pyrene

Abstract: A series of oxidized derivatives of 10-deuterobenzol[a]pyrene (10-D-BaP) were synthesized. Oxidation of 10-D-BaP with sodium dichromate dihydrate yielded the 1,6-, 3,6-, and 6,12-quinones of 10-D-Bap. Upon electrophilic aromatic substitution of 10-D-BaP with sodium nitrate, N-bromosuccinimide, and N-chlorosuccinimide we were afforded 6-nitro-10-D-BaP, 6-bromo-10-D-BaP, and 6-chloro-10-D-BaP, respectively, in high yields. The Vilsmier-Haack reaction of 10-D-BaP provided 6-formyl-10-D-BaP which upon reduction with sodium borohydride, yielded 6-hydroxymethyl-10-D-BaP. Reduction with hydrazine in n-amyl alcohol gave 6-methyl-10-D-BaP. Reduction of 6-nitro-10-D-BaP with hydrazine and Pd/C yielded 6-amino-10-D-BaP. The synthesized compounds, which are known metabolites of benzo[a]pyrene and are useful substrates for metabolism, are important compounds for mechanistic study of the chemical carcinogenesis by benzo[a]pyrene.

Pretreatment of stainless steel prior to coloring

Abstract: PURPOSE:To provide a uniform color tone free from color shading to stainless steel, by subjecting the steel to electrolytic treatment as an anode in a specified acidic and oxidizing pretreating soln. before coloring the steel. CONSTITUTION:Stainless steel is subjected to electrolytic treatment as an anode in a highly oxidizing pretreating soln. of current density for 30sec-10min before coloring the surface of the steel. The soln. contains >=1 kind of compound selected from chromic acid, chromates such as sodium chromate and dichromates such as sodium dichromate by 10-100g/l expressed in terms of CrO3 and 50-300g/l sulfuric acid. By coloring the pretreated steel by a conventional method, a uniform color tone free from color shading can be provided in case of stainless steel plates which are different from each other in history of manufacture as well as the same stainless steel plate.