Showing papers on "Sodium dichromate published in 2019"

Suppressed oxygen evolution during chlorate formation from hypochlorite in the presence of chromium(VI)

Abstract: BACKGROUND: Chromium(VI) is a crucial electrolyte component in industrial chlorate production. Due to its toxicity, iturgently needs to be abandoned and its functions fulfilled by new solutions. In ...

Gelation behavior as a function of concentration of sodium thiosulfate for PAM gels cross-linked with chromium

Abstract: Existing reducing agents for cross-linking polymers are expensive and toxic and mostly limited for water shut off applications. A gelation study was performed on a safer, cheaper, more soluble, and short-lived gel by cross-linking polyacrylamide and chromium as a cross-linking agent using a rheometer and bead-pack porous media. The effect of concentration of sodium thiosulfate as the reducing agent was investigated to determine conditions for optimum yield strength and the gelation time and behavior which has never been published before. For a fixed minimum concentration (for the gel to form) of polyacrylamide and sodium dichromate, the gel yield strength vs. sodium thiosulfate concentration showed a somewhat bell-shaped curve initially increasing, reaching a peak at 2000 ppm, and then starting to decrease. The gelation formed by sodium thiosulfate was comparatively weak and short lived as compared to the ones formed by other reducing agents. Gel started to form instantaneously, reached a peak in 2 h, began to decrease, and then stabilized at 40 cp. The mobility reduction trends were similar to the yield strength curve. The short-lived gel could be useful to improve the waterflood mobility ratio far away from the wellbore without compromising on ease of injectivity.

Phytochemical analysis and nephroprotective effect of cactus (Opuntia ficus-indica) cladodes on sodium dichromate-induced kidney injury in rats.

Abstract: Environmental and occupational exposure to chromium compounds, especially hexavalent chromium, is widely recognized as potentially nephrotoxic in humans and animals. The present study aimed to assess the efficacy of cactus (Opuntia ficus-indica) against sodium dichromate-induced nephrotoxicity, oxidative stress, and genotoxicity. Cactus cladodes extract (CCE) was phytochemically studied and tested in vitro for its potential antioxidant activities. Additionally, the preventive effect of CCE against sodium dichromate-induced renal dysfunction in a Wistar rat model (24 rats) was evaluated. For this purpose, CCE at a dose of 100 mg/kg was orally administered, followed by 10 mg/kg sodium dichromate (intraperitoneal injection). After 40 days of treatment, the rats were sacrificed, and the kidneys were excised for histological, lipid peroxidation, and antioxidant enzyme analyses. The phenol, flavonoid, tannin, ascorbic acid, and carotenoid contents of CCE were considered to be important. Our analyses showed that 1 mL of CCE was equivalent to 982.5 ± 1.79 μg of gallic acid, 294.37 ± 0.84 μg of rutin, 234.78 ± 0.24 μg of catechin, 204.34 ± 1.53 μg of ascorbic acid, and 3.14 ± 0.51 μg of β-carotene. In vivo, pretreatment with CCE was found to provide significant protection against sodium dichromate-induced nephrotoxicity by inhibiting lipid peroxidation, preserving normal antioxidant activities, and protecting renal tissues from lesions and DNA damage. The nephroprotective potential of CCE against sodium dichromate toxicity might be due to its antioxidant properties.

Mutant Frequency is not Increased in Mice Orally Exposed to Sodium Dichromate.

Abstract: The in vivo mutagenicity of hexavalent chromium in the small intestine, the target organ of tumorgenicity, was examined by means of a transgenic mouse gene mutation assay. Sodium dichromate dihydrate was administered orally in drinking water to male gpt delta mice at a dose of 85.7 or 257.4 mg/L for 28 days or at a dose of 8.6, 28.6 or 85.7 mg/L for 90 days. No significant increase in gpt mutant frequency relative to that in control mice was observed in the small intestine in either the 28- or 90-day study, whereas 28-day oral administration of potassium bromate, a positive control substance, increased mutant frequency.

Resource treatment method for chromium-containing sludge

Abstract: The invention discloses a resource treatment method for chromium-containing sludge. The resource treatment method comprises: S1, crushing chromium-containing sludge, and dissolving with a strong acidsolution to obtain a Cr(III)-containing solution; S2, adding an oxidizing agent to the Cr(III)-containing solution, carry out an oxidation reaction to obtain a Cr(VI)-containing solution, adjusting the pH value to achieve an alkaline state, and adding sodium carbonate to precipitate residual metal ions so as to obtain a solution containing sodium chromate and sodium sulfate; S3, adjusting the pH value of the solution containing sodium chromate and sodium sulfate to 2-5 to convert sodium chromate into sodium dichromate so as to obtain a solution containing sodium dichromate and sodium sulfate;and S4, carrying out evaporation concentration and re-crystallization on the solution containing sodium dichromate and sodium sulfate to obtain a sodium dichromate crystal, such that the chromium element is converted into sodium dichromate so as to be recycled. According to the present invention, with the method, chromium-containing sludge can be treated to obtain a sodium dichromate crystal, andthe quality meets the indexes of the first-class products and the qualified products specified in Sodium Dichromate for Industrial Use GB/T1611-2003.

Combined treatment method for discarded sodium dichromate and emulsion

Abstract: The invention discloses a combined treatment method for discarded sodium dichromate and an emulsion The oxidizing property of sodium dichromate and reductibility of an organic matter in the emulsionof a materializing workshop are used, and the emulsion and the sodium dichromate are mixed to cause a redox reaction of a mixed solution, the high-valent chromium ion in sodium dichromate is reduced to a low-toxicity low-valent chromium ion, and the organic matter in the emulsion is removed; the mixed liquid after the reaction is dehydrated by direct pressure filtration, and a separated solid matter is solidified, and the filtered water is introduced to a sewage station after reaching the standard for uniform treatment In this way, by treating waste, the hexavalent chromium in sodium dichromate is reduced to trivalent chromium which is less toxic, and the organic matter in the emulsion is removed, and by sedimentation and pressure filtration, the treated wastewater reaches the standard and is introduced into a sewage treatment system, after the final disposal is qualified, the product is reused, and the filtered sludge enters a solidification workshop for landfill treatment

Method for treating wastewater formed by producing hydrocortisone by adopting chromic anhydride and application of method

Abstract: The invention discloses a method for treating wastewater formed by producing hydrocortisone by adopting chromic anhydride and an application of the method, and relates to the technical field of hydrocortisone preparation. The method includes mixing the wastewater formed by producing the hydrocortisone by adopting the chromic anhydride with a sodium hydroxide aqueous solution; filtering to remove insoluble substances; heating the mixed solution; adding excess oxygen for an oxidation reaction; evaporating the obtained material to remove water until the material is viscous; adding a concentratedsulfuric acid aqueous solution for an acidification reaction; filtering to obtain the aqueous solution; and drying the solution to obtain a mixture containing sodium sulfate and sodium dichromate. Thechromium-containing mixed salt treated by the method can replace the chromic anhydride to preform a reoxidation reaction, so that the environmental protection pressure produced by current hydrocortisone enterprises is relieved; the bipolar membrane treatment is preformed on the byproduct sodium sulfate obtained after treatment to obtain a sodium hydroxide and sulfuric acid solution; and after reprocessing, the sodium hydroxide and sulfuric acid solution is recycled to a treatment section of chromium-containing wastewater, so that materials in the whole process are recycled, and material wasteis reduced.

Device and technology for treating acidic wastewater by producing expansible graphite through sodium dichromate process

Abstract: The invention discloses a device for treating acidic wastewater by producing expansible graphite through a sodium dichromate process. The device comprises a graphite recycling unit, a regulating unit,a reduction reaction unit, a neutral reaction unit, a filter pressing unit, a liquid storage unit and a filtering unit, wherein the graphite recycling unit is used for recycling expansible graphite particles; the regulating unit is used for balancing water quality; the reduction reaction unit is used for reducing hexavalent chromium in wastewater into trivalent chromium; the filter pressing unitis used for dewatering and drying the generated sludge; the filtering unit is used for removing heavy metal particles and suspended solids formed in wastewater; all the units are connected with each other in turn. The invention also discloses a technology for treating acidic wastewater by producing expansible graphite through the sodium dichromate process. According to the invention, wastewater treatment is stable and reaches standard, treatment load is high and treatment cost is low.

Quick test for methanol and ethylene glycol detection in alcoholic drinks

Abstract: Novelty: a method for the detection of high-level methanol or/and ethylene glycol in alcoholic drinks is disclosed. Purpose: to completely convert alcohols to carbon dioxide and ethanol to liquid ethanoic acid. Detection process: the sample of the alcoholic drink is introduced in a vessel-reactor containing hexavalent chromium trioxide with traces of thick sulfuric acid solution and sodium dichromate; the aforementioned elements are supported on low-granularity zeolite. Being in contact with the material of the reactor, the alcohols of the drink react very quickly on the basis of the below-mentioned reactions (see chemical formula). The reactions describe the very fast Jones oxidation of the alcohols of the sample. The produced carbon dioxide is drawn through a tube to the detection vessel containing a sodium hydroxide solution and rose-colored phenolphthalein. Due to the pH reduction caused by carbon dioxide entering the detection vessel, the colour of the solution disappears.

Method of extracting vanadium and chromium from vanadium-chromium slag

Abstract: FIELD: metallurgy.SUBSTANCE: invention relates to metallurgy of vanadium and chromium, particularly to utilization of vanadium and chromium contained in vanadium-chrome slags. Method comprises the following steps: a. obtaining mixture of slags with calcined soda and aluminum salt, from which granules are obtained, b. annealing granules containing vanadium-chromium slag, resulting in granules of sintered material; c. obtaining granules of sintered material for water leaching and subsequent separation of leached suspension into solid substance and liquid, resulting in obtaining a solution containing vanadium and chromium, and residues; d. adding calcium oxide to precipitate vanadium for time of 50 to 120 minutes, and obtaining unrefined calcium vanadate and a chromium-containing solution; e. obtaining purified calcium vanadate and flushing water containing vanadium and chromium; wherein washing water containing vanadium and chromium is used for leaching burnt sintered material; f. obtaining sodium dichromate from a chromium-containing solution through carbonization and using a byproduct, sodium bicarbonate, as a sodium-containing additive during vanadium-chrome slag burning.EFFECT: effective utilization of vanadium and chromium from slags.6 cl, 3 ex

Composite catalyst for propiconazole cyclization reaction and preparation method thereof

Abstract: A composite catalyst for propiconazole cyclization reaction and a preparation method thereof are disclosed, the composite catalyst is prepared from the following raw materials in parts by weight: 1.5-3.5 parts of zinc trifluoromethanesulfonate, 0.8 to 2.2 parts of sodium trinitrobenzene sulfonate, 0.6 to 1.4 parts of sodium dichromate and 9.5-10.6 parts of a catalyst carrier; according to the preparation method disclosed by the invention, the zinc trifluoromethanesulfonate, the sodium trinitrobenzene sulfonate and the sodium dichromate are compounded together through the catalyst carrier to prepare the composite catalyst, and the composite catalyst is good in stability and excellent in performance, so that the reaction medium environment of the propiconazole cyclization reaction can be improved, the rate of the propiconazole cyclization reaction and the yield of a cyclization substance are increased, the recovery is convenient and thorough, no impurities can be brought to the subsequent bromination reaction, the yield of the bromination reaction is not affected, and the yield and purity of the final propiconazole original medicine are improved.

Evaporative concentration apparatus and concentration technology for sodium dichromate

Abstract: The invention discloses an evaporative concentration apparatus for sodium dichromate. The apparatus comprises a preheating device, a falling film evaporation device, a forced circulation evaporation device and a vapor compression device which are sequentially connected, and further comprises an automatic control system connected with the above devices. The apparatus has the advantages of simple structure, small occupied area, realization of the automatic treatment process of high-efficiency concentration of a sodium dichromate solution from a low density to a high density, low energy consumption and no damage to the environment. The invention also discloses a concentration technology for sodium dichromate. The technology includes the following steps: preheating of a stock solution, first-stage evaporative concentration, two-stage evaporative concentration, and vapor compression for finally obtaining a sodium dichromate concentrate having a density of 58 DEG Be. The technology has the characteristics of simple process steps, low energy consumption and low production cost. Compared with conventional technologies, the technology utilizing the MVR technique has the advantages of high automation degree and high product yield.

Exploration of croconic acid disodium salt as an organic battery electrode material

Abstract: We investigated croconic acid disodium salt for potential use as Li-ion battery material. The crystal was shown to be a promising electrode material with a medium to short battery cycle lifetime. We embarked in a thorough computational study based on classical molecular dynamics simulations to characterize this system and identify optimization strategies to improve battery lifetime. Through long-timescale molecular dynamics simulations in the Canonical Ensemble and Isothermal-Isobaric ensembles, we first established that the custom force field that we generated for this system reproduces the known thermodynamics of the Croconic acid disodium salt dihydrate crystal. In a second step, we predict the existence of a quasi-degenerate denser polymorph which is slightly less stable at room temperature and becomes more stable starting T=420K compared to the known crystal structure as determined by X-Ray crystallography. Interestingly, we find that upon adding lithium the system chooses the denser phase even at room temperature. Lithiation of the denser phase leads to moderate volume increases of about 0.75% for each additional 1% lithiation. By extrapolation of the results of the simulations, we conjecture that a phase transition takes place in the very first stages of lithiation. This should initially reduce the volume, resulting in the formation of cracks in the material contributing to a short battery cycle lifetime. We thus propose to assemble batteries based on croconate at an elevated temperature.

Synthetic process of isatin

Abstract: The invention discloses a synthetic process of isatin, comprising the steps of S1, adding indigo, water and copper dichloride into a reactor, heating a reaction system to 60-90 DEG C, stirring to allow dissolving, introducing pure oxygen slowly, and allowing to react at 60-90 DEG C for 3-6 h; S2, filtering when the temperature is 60-90 DEG C, washing filter cake with water once to three times, anddrying at 80-100 DEG C to obtain isatin. Water is used as a solvent to the reaction system herein, using massive sulfuric acid is not required, and the water as the solvent is reusable; oxygen is used as a catalyst and is nontoxic and clean as compared to sodium dichromate, and sodium dichromate is of heavy metal type and explosive type and is highly dangerous to the environment, while oxygen isnontoxic and harmless; indigo is used as the raw material which is low in price, and industrial production of indigo helps greatly reduce the production cost; the yield of the synthetic process reaches 85% which is evidently higher than the prior yield which is 70-80%.

Method for removing chlorine of sodium dichromate by electrolysis

Abstract: The invention discloses a method for removing chlorine of sodium dichromate by electrolysis. The method includes the following steps: an anolyte and a catholyte are heated for raising temperature; theanolyte is a sodium dichromate solution or a sodium chromate alkaline solution; the catholyte is a sodium hydroxide solution or a sodium chromate solution; an electrolytic cell circulation pump is turned on, the anolyte is pumped into an anode cavity in an electrolytic cell through an anode pump, the catholyte is pumped into a cathode cavity in the electrolytic cell through a cathode pump, and direct current is introduced to an anode plate of the anode cavity and a cathode plate of the cathode cavity for performing electrolysis; wherein the electrolytic cell is a diaphragm electrolytic cell;and a separation diaphragm is disposed between the cathode cavity and the anode cavity of the diaphragm electrolytic cell. The method can acidify the sodium dichromate solution while the chlorine is removed by the electrolysis, the amount of sulfuric acid acidification added during a production process of the sodium dichromate can be reduced to some extent, new impurities are not introduced in a whole process, the content of chloride ions is reduced, the quality of a product is improved, and during a process, the quantity of output of by-product mirabilite in production of the sodium dichromate is reduced.

Desulfurizer for coal washing

Abstract: The invention belongs to the technical field of desulfurizers, and particularly relates to a desulfurizer for desulfurizing of coal washing, which aims at providing a desulfurizer with the purposes ofeffectively complexing and cleaning inorganic sulfur in the coal and generating the sulfides and other harmful matters into harmful matters via chemical reaction. The desulfurizer is prepared from the following raw materials in parts by weight according: 10 to 25 parts of sodium hypochlorite, 12 to 20 parts of ammonium persulfate, 5 to 12 parts of sodium glycollate, 6 to 10 parts of sodium acetate, 7 to 12 parts of potassium citrate, 6 to 8 parts of sodium gluconate, 5 to 9 parts of ethylenediamine tetraacetic acid, 1 to 12 parts of ferric sulfate, 10 to 15 parts of triethanolamine, 3 to 9 parts of sodium dichromate, 3 to 5 parts of aluminum ferric chloride, 1 to 2 parts of urea, 3 to 5 parts of sodium bicarbonate, 0.1 to 0.5 part of octadecyl trimethyl ammonium chloride, 0.5 to 0.8 partof sodium dodecyl benzene sulfonate, 0.2 to 0.4 part of a dispersant, and 50 to 90 parts of water.