48 results about "Potassium chromate" patented technology

The invention belongs to the technical field of crystal defect testing, and particularly relates to an FPD testing method for a monocrystalline silicon wafer micro-viewpoint defect, which comprises the following steps: accurately cutting off the head and the tail of a silicon rod to eliminate an end defect, and preparing a pure substrate by adopting an A-surface machine grinding / B-surface maintaining asymmetric treatment and segmented cleaning process; after pretreatment with a specifically proportioned corrosive liquid, carrying out temperature-controlled etching by using potassium dichromate-hydrofluoric acid to form a characteristic V-shaped pattern on the surface, and realizing visual identification by corresponding different defects to different patterns; gridding detection points are designed based on stress distribution, laser positioning coordinate mapping is performed, an imaging-correction-noise reduction-segmentation-intelligent classification algorithm chain is constructed to realize full-automatic detection, and a detection-analysis-optimization full-process data driving quality control system is established through visual data such as a thermodynamic diagram and a type matrix. And large-scale production of semiconductor silicon wafers is supported.

The invention discloses an ultrahigh-burning-speed double-layer ignition sheet in the technical field of thermal batteries, and the ultrahigh-burning-speed double-layer ignition sheet is prepared by the following steps: step 1, slurry preparation: using distilled water to immerse loose asbestos paper until the loose asbestos paper is soft, then crushing the loose asbestos paper, adding zirconium powder, and uniformly mixing to obtain a zirconium powder paper pulp solution; respectively adding barium chloride and potassium chromate into the zirconium powder paper pulp solution in a stirring state to obtain a turbid liquid containing the loose asbestos, the zirconium powder and the barium chromate, performing suction filtration to obtain a mixture containing the barium chromate, the zirconium powder and the loose asbestos, dispersing the mixture in an adhesive, and uniformly stirring to obtain slurry; wherein the mass ratio of the loose asbestos to the barium chloride to the zirconium powder to the potassium chromate is (1-10): (35-45): (15-20): (25-35); and secondly, the slurry prepared in the first step is sprayed on an ultra-high-burning-rate Al-Ni film, drying is conducted for 1.5-2.5 h under the condition of 120-180 DEG C in argon shielding gas, and the ultra-high-burning-rate double-layer ignition sheet is obtained. Compared with the prior art, the ultrahigh-burning-speed double-layer ignition sheet prepared by the invention is higher in burning speed.

The present application relates to a special coating for water-cooled wall surface of coal-fired boiler, in particular to a coating for water-cooled wall surface of coal-fired boiler, a preparation method and application thereof. The coating comprises nano-tungsten powder, tungsten carbide, rare earth compound, sodium borate, potassium chromate, rock asphalt, binder, modifier, dispersant, defoaming agent, curing agent and solvent. The coating is fused on the water-cooled wall surface of coal-fired boiler, the obtained coating has good interface bonding with the water-cooled wall base material, low porosity, avoids the penetration of corrosive gas and liquid, solves the corrosion problem of water-cooled wall, and also avoids the reduction of coating hardness and wear resistance; the coating is not easy to wear and damage in long-term use, can improve the high-temperature resistance, hardness, corrosion resistance and wear resistance of the water-cooled wall surface of boiler, effectively prolongs the service life of the water-cooled wall surface of boiler, and further ensures the safe and stable operation of coal-fired boiler.

Provided is a large specific surface area isomelanin-based carbon nanomaterial and a preparation method thereof. The preparation method of the isomelanin nanomaterial is to prepare a mixed solution of 1,8-dihydroxynaphthalene in acetone and water, and add a trichloride hexahydrate iron solution to the solution to form a 1,8-dihydroxynaphthalene-iron ion complex solution, then add a potassium dichromate solution to stir the reaction to obtain a black turbid solution, and centrifuge and wash to obtain the isomelanin nanomaterial; the isomelanin nanomaterial is subjected to high temperature heat treatment under an inert atmosphere, and KOH activation is performed to obtain an isomelanin nanomaterial with a large specific surface area. The preparation method of a supercapacitor electrode sheet is to mix the prepared carbon nanomaterial, carbon black and polytetrafluoroethylene, ultrasonically disperse them in an aqueous solution, dry them, roll them to obtain a black film, and press them on a current collector to obtain an electrode sheet. The isomelanin nanomaterial with a large specific surface area prepared by the method has high specific capacitance and cycle stability, and has broad applications in energy fields including supercapacitors.

The invention discloses a fluoride-salt-free and nitrate-free steel plate enamel high-temperature titanium creamy yellow cover glaze as well as a preparation method and application thereof, and belongs to the technical field of enamel. The cover glaze is prepared from quartz, anhydrous borax, rutile, potassium feldspar, trisodium phosphate, potassium carbonate, potassium dichromate and zinc oxide according to a specific mass ratio. The preparation method comprises the following steps: mixing the raw materials, melting at 1300 + / -10 DEG C in a pure oxygen environment, and quenching after wiredrawing to detect a molten state. The overglaze completely avoids the use of fluoride salt and nitrate, the problems of fluoride emission and environmental protection equipment blockage are solved from the source, the fluorine content of the product is not detected through detection, the product meets the European Union REACH regulation limit value requirements, and meanwhile, the overglaze has good hue, luster and firing adaptability, is suitable for a steel plate matrix, has the firing temperature of 840-880 DEG C and the firing time of 820-830 minutes, and has good application prospects. The method can be used for producing green and environment-friendly enamel products.

The invention discloses a recycling system and process for plastic masterbatches. The plastic masterbatches are subjected to pretreatment, differentiation treatment and purification treatment in sequence by using a pretreatment unit, a differentiation unit, a purification unit and a transport unit. The pretreatment unit processes the plastic masterbatches into particles with consistent particle size and glossiness. In the subsequent potassium chromate treatment, the chroma and glossiness of organic masterbatches and inorganic masterbatches can be more obviously contrasted. After the chroma and glossiness of the plastic masterbatches with consistent particle size and glossiness are changed, the consistency of the particles in the subsequent treatment process can be ensured, and the accuracy of the differentiation process is improved. The potassium chromate treatment in the differentiation treatment can change the glossiness and chroma of the organic masterbatches and the inorganic masterbatches. The organic masterbatches and the inorganic masterbatches can be differentiated according to the glossiness and chroma changes of the organic masterbatches and the inorganic masterbatches after the potassium chromate treatment, thereby solving the defect in the prior art that the organic and inorganic masterbatches cannot be accurately recycled respectively.

The invention provides a method and device for detecting chlorine components in an oilfield chemical agent and application, and the method for detecting the chlorine components in the oilfield chemical agent comprises the following steps: pretreating a sample, and extracting the total chlorine components in the sample to obtain a to-be-detected solution containing the total chlorine components of the sample; mixing a potassium chromate aqueous solution with the to-be-detected solution; diluting the silver nitrate aqueous solution into a standard working solution with a concentration gradient; dropwise adding the standard working solution into the to-be-detected solution according to the concentration sequence from low to high until the color of the solution is just changed; and recording the consumption drop number of the standard working solution under each concentration so as to calculate the total chlorine component content. According to the method, a series of standard working solutions diluted by the silver nitrate aqueous solution with the concentration gradient are prepared, so that the measuring range is enlarged, the method is suitable for detecting the oilfield chemical agents with different chloride ion concentrations, and the chlorine content in the oilfield chemical agents can be rapidly detected.

The present invention discloses a modification method for polyethylene suspension fillers used in a moving bed biofilm reactor. This method uses polyethylene fillers as the matrix. After treating the surface of the fillers with an acidic potassium dichromate mixed solution, it is immersed in an aqueous solution of a coupling agent (silane coupling agent KH-560, silane coupling agent KH-570, titanate coupling agent CS-311), and activated carbon powder and gelatin protein as modifiers are added, successfully loading activated carbon and gelatin protein onto the surface of the fillers. Based on conventional polyethylene fillers, after treating the surface with an acidic potassium dichromate mixed solution, the present invention utilizes the cross-linking reaction of the coupling agent with macromolecular compounds to make the surface of the fillers carry hydrophilic groups such as hydroxyl and carbonyl groups, providing favorable conditions for the rapid growth of microorganisms on the surface of the fillers and enhancing the film-forming effect of the fillers. During the sewage treatment process, it is superior to conventional fillers in terms of the film-forming speed of the fillers, the amount of biofilm, the tightness between the biofilm and the carrier, and the microbial activity, etc.

The invention discloses a method for measuring dissolved oxygen in aquaculture tail water by a spectrophotometric method based on an iodine-ascorbic acid-potassium dichromate system, and belongs to the technical field of water quality detection. The method comprises the following steps: sequentially adding a manganese sulfate solution and an alkaline potassium iodide solution into a to-be-detected culture tail water sample, sealing a container, fully reacting, and standing after the reaction is finished to completely precipitate Mn2O3; adding a citric acid solution, sealing, reacting, completely dissolving the precipitate and releasing the iodine elementary substance, adding water and an ascorbic acid-potassium dichromate mixed color developing agent into the solution after the reaction is finished, fixing the volume, sealing, uniformly mixing, and carrying out a color developing reaction in a dark place; a blank sample is used for reference, the culture tail water subjected to color development is placed in a sample pool of a spectrophotometer, the spectrophotometric value of the sample is measured at the wavelength of 360 nm, and the dissolved oxygen concentration is calculated according to a standard curvilinear equation. The method provided by the invention reduces the detection limit of the traditional spectrophotometric method, and has the advantages of high sensitivity, strong anti-interference capability, high speed and rapidness in operation, wide application range, greenness and environmental protection.

The embodiment of the invention relates to a method for measuring the chloride ion concentration in water-based drilling fluid, which comprises the following steps: acquiring the voltage of a chloride ion sensor in various standard liquids with known concentrations at a preset constant temperature, and establishing a calibration corresponding relation between the voltage and the chloride ion concentration; diluting a to-be-detected water-based drilling fluid sample into a to-be-detected mixed solution according to a fixed proportion; and maintaining the to-be-measured mixed solution at the constant temperature, measuring the voltage of the to-be-measured mixed solution by using a chloride ion sensor, determining the concentration value of the to-be-measured mixed solution based on the calibration corresponding relation, and calculating the actual chloride ion concentration value of the water-based drilling fluid by combining the fixed proportion. According to the embodiment, a traditional chemical titration agent is abandoned, the potential safety hazard that an operator makes contact with toxic strong acid and carcinogenic potassium chromate is eliminated, the water-based drilling fluid to be detected is adjusted to the optimal linear range of a chloride ion sensor through quantitative dilution, and the detection efficiency and timeliness are greatly improved.

The invention relates to a method for improving Fe < 2 + > detection precision by decarburization through a magnetic separation method. The method comprises the following steps: weighing a detection sample; carrying out magnetic separation on the weighed sample by using a small high-intensity magnetic separator, and separating carbon from iron minerals by virtue of magnetic difference through separation of the magnetic separator; determining the ratio of iron minerals to carbon content in the sample; measuring the ferrous content of the separated iron mineral sample by a potassium dichromate volumetric method; calculating the ferrous content in the whole sample according to the determined proportion of the iron mineral content to the carbon content in the sample; according to the method, the carbon in the test sample is abandoned in advance through the magnetic separation process, so that the titration end point of the potassium dichromate volumetric method is determined more accurately, the detection process is simple and easy to operate, and the accuracy of the test result of the Fe < 2 + > content of the carbonaceous iron minerals is greatly improved.

The application discloses a steel plate enamel high-temperature titanium milk yellow face glaze free of fluorinated salt and nitrate, a preparation method and application thereof, and belongs to the technical field of enamel. The face glaze is prepared from quartz, zero-water borax, rutile, potassium feldspar, trisodium phosphate, potassium carbonate, potassium dichromate and zinc oxide according to specific mass proportions. The preparation comprises raw material mixing, smelting at 1300+ / -10 DEG C under a pure oxygen environment, and rapid cooling after wire drawing detection of the smelting state. The face glaze completely avoids the use of fluorinated salt and nitrate, eliminates fluorine emission and environmental protection equipment blockage problems from the source, the fluorine content of the product is not detected through detection, meets the limit value requirements of the EU REACH regulation, has good color, gloss and firing adaptability, is suitable for a steel plate substrate, has a firing temperature of 840-880 DEG C, and can be used for the production of green and environmentally-friendly enamel products.

The application discloses a kind of light absorption material glass for high-definition ultra-short inverter and preparation method thereof, and the light absorption material glass includes the following weight percentage components: quartz sand 40-50%, boric acid 6-12%, alumina 7-15%, sodium carbonate 1-10%, potassium carbonate 1-10%, lithium carbonate 0-2%, basic magnesium carbonate 0-3%, calcium carbonate 0-5%, barium nitrate 1-3%, zirconium oxide 0-3%, copper oxide 1-3%, potassium permanganate 3-6%, potassium chromate 0.2-1%, diiron trioxide 1-5%, cobalt trioxide 1-6%, nickel oxide 1-6%, vanadium pentoxide 1-6%, cerium oxide 0-1%. The light absorption material glass of the application is used for preparing ultra-short inverter, which can effectively improve the transmittance and resolution of ultra-short inverter.

The invention relates to the technical field of chemical analysis, and relates to a method for measuring the content of an iron phase in iron-containing dust slime, which comprises the following steps: 1, preparing an iron-containing dust slime sample, and carrying out ball milling processing on the iron-containing dust slime to obtain an iron phase sample; 2, weighing an iron phase sample A0, placing the iron phase sample A0 in a container, adsorbing magnetic substances in the iron phase sample A0 by adopting a magnet, respectively weighing the adsorbed magnetic substance A1 and the remaining sample A '0, and detecting the content of magnetic metal iron in the magnetic substance A1 by utilizing a potassium dichromate method; step 3, mixing the residual sample A '0 with anhydrous sodium carbonate according to a mass fraction ratio of 1: (2-5), marking the mass fraction ratio of the anhydrous sodium carbonate to the residual sample A' 0 as k, and marking the fully ground and uniformly mixed sample as A '' 0; respectively detecting the contents of wFe < 1 >, wFe < 2 > and wFe < 3 > in the weighed uniformly mixed sample by using a potassium dichromate method; and 4, carrying out normalization calculation on the content results obtained in the step 2 and the step 3 to finally obtain the contents of total iron (TFe), metallic iron (MFe), ferrous iron (Fe < 2 + >) and ferric iron (Fe < 3 + >) in the iron phase sample A0.

The invention discloses a formula of an eosin staining solution, and every 1000 ml of the eosin staining solution comprises the following components: 5-8 g of eosin which is any one of water-soluble eosin Y or alcohol-soluble eosin Y; 2.5 to 3.5 g of potassium dichromate; 5-25 g of picric acid; 5 to 60 ml of absolute ethyl alcohol; the balance is water, and the water is any one of deionized water or distilled water. According to the eosin staining solution formula disclosed by the invention, the absolute ethyl alcohol not only can promote good dissolution of all the components and effectively ensure a good uniform mixing effect among all the components, but also can be used as a dehydrating agent and can play a role in dehydrating and fixing cells, so that a cell environment in tissues is similar to the tissues, cell coloring in the tissues is facilitated, and the quality of the cells in the tissues is improved. The dyeing liquid has a certain level dyeing effect, is clear in coloring, avoids overdyeing, uneven dyeing and other conditions, utilizes the synergistic effect of potassium dichromate and picric acid, promotes the dissolution of each component, ensures the stability of the dyeing liquid, is simpler to prepare, is not easy to fade, and has a longer period of validity.

The invention discloses fluoride-salt-free and nitrate-free low-temperature titanium creamy yellow surface glaze for steel plate enamel as well as a preparation method and application of the surface glaze, and belongs to the technical field of enamel. The cover glaze is prepared from quartz, borax anhydrous, trisodium phosphate, titanium dioxide, potassium feldspar, magnesium carbonate, potassium carbonate, potassium dichromate and zinc oxide according to a specific mass ratio. The preparation method comprises the following steps: mixing the raw materials, melting at 1300 + / -10 DEG C in a pure oxygen environment, and quenching after wiredrawing to detect a molten state. The overglaze completely avoids the use of fluoride salt and nitrate, the problems of fluoride emission and environmental protection equipment blockage are solved from the source, the fluorine content of the product is not detected through detection, the limit value requirement of the European Union REACH regulation is met, meanwhile, the overglaze has good hue, luster and firing adaptability and is suitable for a steel plate matrix, the firing temperature is 760-800 DEG C, and the firing time is 2-3 hours. The method can be used for producing green and environment-friendly enamel products.

The invention provides a conductive oxidation solution for an aluminum alloy material and a conductive oxidation method for the aluminum alloy material, and belongs to the technical field of alloy material surface protection. The conductive oxidation liquid for the aluminum alloy material comprises the following components: 2.5 g / L to 3 g / L of chromic anhydride, 2.0 g / L to 2.5 g / L of potassium dichromate and 1 g / L to 1.2 g / L of sodium fluoride. The conductive oxidation liquid for the aluminum alloy material is adopted for chemical oxidation, and a conductive oxidation layer formed on the surface of the aluminum alloy not only has good conductivity, but also has good corrosion resistance and high-temperature stability.

The invention discloses a preparation method of a high-entropy oxide catalyst for CO2 hydrogenation, and belongs to the field of catalyst preparation. Comprising the steps that hydrated salt particles of Co, Ni, Cu and Zn are selected and put into a ball mill to be evenly ground for 30 min; adding alkaline sylvite to provide an alkaline environment for the catalyst system, and continuously grinding for a period of time; adding potassium chromate and an oxidation catalyst system, continuously grinding for a period of time to oxidize Co < 2 + > into Co < 3 + >, and reducing the potassium chromate into an oxide; and washing the ground product with a solvent to prepare the CoCrNiCuZnOx catalyst. The preparation method has the beneficial effects that mechanochemical synthesis is carried out by adopting a ball milling method, the catalyst can be prepared only through room-temperature grinding and subsequent washing steps, the requirement of high-temperature calcination is avoided, and the energy consumption and the cost are remarkably reduced. The method is simple, efficient and suitable for large-scale commercial production.

The invention belongs to the technical field of nano materials, and particularly relates to a preparation and transfer method of an inclined chromic oxide single-crystal nanosheet. The preparation method specifically comprises the following steps: uniformly mixing potassium chromate and chromic chloride to obtain precursor powder; transferring the precursor powder into a porcelain boat, and covering the surface of the precursor powder with a molecular sieve; enabling the oxide layer of the SiO2 / Si substrate to face downwards and obliquely cover the molecular sieve; and then transferring into a vacuum tube furnace, heating and reacting, and cooling to obtain the inclined chromic oxide single crystal nanosheet on the surface of the SiO2 / Si substrate. The inclined chromium oxide single crystal nanosheet is placed on other clean substrates, and the chromium oxide single crystal nanosheet is transferred to other clean substrates through mechanical pressing. The method provided by the invention has the advantages of good controllability, good repeatability, high yield, low cost, no pollution in transfer and the like.

The invention belongs to the technical field of ferrite core processing aids, and discloses a chemical polishing solution for a ferrite product as well as a preparation method and application of the chemical polishing solution. The chemical polishing solution comprises, by mass, 4%-8% of sulfuric acid, 2%-5% of phytic acid, 1%-6% of potassium dichromate, 0.5%-5% of polyether modified polysiloxane quaternary ammonium salt, 0.2%-2% of sodium chloride and the balance water. According to the chemical polishing solution disclosed by the invention, the phytic acid is used for replacing conventional phosphoric acid and is compounded with sulfuric acid and potassium dichromate, so that the polishing process of the dichromic acid and sulfuric acid with strong oxidizing property on the surface of a ferrite product can be effectively coordinated; and the chemical polishing effect of the ferrite product is obviously improved.

This invention discloses a method for degreasing ceramic packing, relating to the field of degreasing technology. The method involves preparing a degreasing solution, injecting it into the packed tower, and circulating it using a reflux pump. The degreasing solution includes sulfuric acid, potassium dichromate, and hydrogen peroxide. This invention employs an innovative degreasing solution that effectively removes siloxanes from the surface of the ceramic packing, significantly improving clogging and eliminating clogging issues after a period of use, thus meeting production requirements.

The invention discloses a ferric oxide / phosphomolybdic acid composite material and a preparation method and use thereof. Firstly, Fe2O3 nanoparticles and Dawson type phosphomolybdic acid P2Mo are prepared. 18 ; Tetrabutylammonium bromide was used as a surfactant to convert Dawson type P2Mo 18 The ferric oxide / phosphomolybdic acid composite material is prepared by compounding with Fe2O3 nanoparticles, and the preparation process is simple. The prepared ferric oxide / phosphomolybdic acid composite material can photocatalytically degrade methylene blue and potassium dichromate, and the degradation effect is good. The final degradation rate of methylene blue can reach 99%, and the degradation rate of potassium dichromate solution after adding methanol can reach 96%.

The invention discloses a fluoride-salt-free and nitrate-free medium-temperature titanium creamy yellow overglaze for steel plate enamel as well as a preparation method and application of the overglaze, and belongs to the technical field of enamel. The cover glaze is prepared from quartz, anhydrous borax, rutile, potassium feldspar, magnesium carbonate, trisodium phosphate, calcium carbonate, potassium dichromate and zinc oxide according to a specific mass ratio. The preparation method comprises the following steps: mixing the raw materials, melting at 1300 + / -10 DEG C in a pure oxygen environment, and quenching after wiredrawing to detect a molten state. The overglaze completely avoids the use of fluoride salt and nitrate, eliminates the problems of fluoride emission and environmental protection equipment blockage from the source, the fluorine content of the product is not detected through detection, the product meets the European Union REACH regulation limit value requirements, has good hue, luster and firing adaptability, is suitable for a steel plate matrix, has the firing temperature of 800-840 DEG C and the firing time of 20-30 minutes, and can be widely applied to the production of steel plates. The method can be used for producing green and environment-friendly enamel products.

The application discloses a steel plate enamel medium-temperature titanium milk yellow face glaze free of fluorinated salt and nitrate, a preparation method and application thereof, and belongs to the technical field of enamel. The face glaze is prepared from quartz, zero-water borax, rutile, potassium feldspar, magnesium carbonate, trisodium phosphate, calcium carbonate, potassium dichromate and zinc oxide according to specific mass proportions. The preparation comprises raw material mixing, smelting at 1300+ / -10 DEG C under a pure oxygen environment, and rapid cooling after wire drawing detection of the smelting state. The face glaze completely avoids the use of fluorinated salt and nitrate, eliminates fluorine emission and environmental protection equipment blockage problems from the source, the fluorine content of the product is not detected through detection, meets the limit value requirements of the EU REACH regulation, has good color, gloss and firing adaptability, is suitable for a steel plate substrate, has a firing temperature of 800-840 DEG C, and can be used for the production of green and environmentally-friendly enamel products.

A method for measuring the ferrous iron content in a laterite nickel ore, comprising the following steps: (1) decomposing a laterite nickel ore sample by using a first mixed acid solution to obtain a sample solution; (2) mixing a second mixed acid solution and the sample solution, and dropwisely adding sodium diphenylamine sulfonate to the obtained mixed solution as an indicator; (3) titrating the mixed solution by using a potassium dichromate standard solution, a titration endpoint being reached when the color of the solution changes to purple blue; and (4) calculating the ferrous iron content in the laterite nickel ore sample on the basis of the consumption amount of the potassium dichromate standard solution, wherein the first mixed acid solution in step (1) comprises a sulfuric acid solution and a hydrofluoric acid solution, and the second mixed acid solution in step (2) comprises a sulfuric acid solution, a phosphoric acid solution and a boric acid solution.

The invention discloses a method for manually detecting chlorine ion content in gas water. The method comprises the following steps: acquiring to-be-detected gas with a certain volume; introducing the coal gas to be detected into a potassium hydroxide solution until no new precipitate is generated; filtering by using quick quantitative filter paper until the water is clear and has no obvious color; transferring the filtered liquid into a 250mL conical flask, adding two drops of phenolphthalein indicator, and adjusting the pH value by using a nitric acid solution until the pH value is just changed to be colorless from red; and adding a potassium chromate indicator, and titrating with a silver nitrate standard titration solution until brick red appears. Through the systematic pretreatment and manual titration steps, the chlorine ion content in the gas water can be rapidly, accurately and reliably measured; the time of the whole process is controlled within 30 minutes from sampling to titration completion; the pretreatment and determination time required by traditional manual titration is greatly shortened.

The invention discloses a method for determining the content of free chlorine in a chlorine-containing organic matter, which comprises the following steps: a) mixing a sample to be detected with the volume of V sample and a water-insoluble organic solvent to form a mixed organic phase, then adding a water phase containing neutral salt or a phosphate buffer solution with the pH value of neutral with the volume of V water, and oscillating; b) after standing and layering, separating a water phase; c) adding a potassium chromate indicator into the water phase with the volume of Vwater ', titrating with a silver nitrate standard solution with the concentration of C until the water phase becomes red, and recording the volume V of the consumed silver nitrate standard solution; d) blank test: under the condition of not adding the sample, repeating the steps a) to c), and recording the volume V0 of the consumed silver nitrate standard solution; and e) substituting the obtained V sample, V water, V water ', C, V0 and V into the following formula to calculate the free chlorine content WCl. According to the method, through a specific organic medium environment, effective separation of free chlorine and main interferents is realized, and the determination is accurate.

The invention discloses a device and a method for on-line measurement of chloride ions in sewage of a urea hydrolyzer, an outlet of a first sampling valve is communicated with a reaction center through a coil cooler, a filter tube, a cation exchange column and a reverse osmosis unit in sequence, and a luminescent tube is arranged on one side in the reaction center; a color sensor is arranged on the other side in the reaction center; an outlet of the second demineralized water reagent bottle, an outlet of the phenolphthalein indicator reagent bottle, an outlet of the nitric acid solution reagent bottle, an outlet of the sodium hydroxide solution reagent bottle, an outlet of the potassium chromate solution reagent bottle and an outlet of the silver nitrate standard solution reagent bottle are communicated with an inlet of the multi-channel switching valve, and an outlet of the multi-channel switching valve is communicated with the reaction center; according to the device and the method, the chloride ion concentration in the sewage of the urea hydrolyzer can be measured on line.

The invention relates to a method for selectively and efficiently separating and recovering chromium from vanadium and chromium slag leaching liquid. According to the technical scheme, the method comprises the steps that vanadium and chromium slag sub-molten salt is subjected to alkaline leaching, and vanadium and chromium slag leaching liquid is obtained; and the vanadium and chromium slag leaching solution is put into an evaporation device to be evaporated and concentrated, and the vanadium and chromium slag alkaline leaching concentrated solution is obtained. Putting the vanadium and chromium slag alkaline leaching concentrated solution into a crystallizer, adding a potassium-containing additive into the vanadium and chromium slag alkaline leaching concentrated solution, and carrying out reaction, solid-liquid separation and washing under a first stirring condition to obtain potassium sodium chromate crystals and a post-crystallization solution; dissolving the potassium sodium chromate crystal to obtain a potassium sodium chromate solution, and adjusting the pH value with sulfuric acid; and adding sodium sulfite into the potassium sodium chromate solution, reacting under a second stirring condition, and carrying out solid-liquid separation to obtain a chromium hydroxide solid. And calcining the chromium hydroxide solid to obtain chromium sesquioxide. The method has the characteristics of simple process, low cost, strong adaptability and environmental friendliness, is suitable for the vanadium-chromium-containing solution with high strong alkalinity, and is good in vanadium-chromium separation effect and high in chromium recovery rate.

The invention discloses a method for quantitatively determining cellulose in a plant sample. The process comprises a series of precise steps for extracting and measuring the cellulose content, and calibration is carried out by using a standard starch curve. Initially, a plant leaf sample is freeze-dried at a temperature of-30 DEG C to-40 DEG C for at least 3 days to ensure complete freezing, and then ground and screened through a 40-60 mesh screen. And then storing the dried sample at-20 DEG C for further use. 0.05 g of a dried sample is transferred into a 50 ml centrifugal tube, and 10 ml of acetate-nitrate is added into the centrifugal tube; putting the mixture into a boiling water bath, heating for 25 minutes, and stirring; after heating, centrifuging a sample at 8000rpm for 15 minutes, and then washing with deionized water; and adding a potassium dichromate-sulfuric acid mixture to further treat the sample. A series of starch standard substances are prepared and are subjected to similar treatment with plant samples, and a cellulose quantitative standard curve is established. And finally, measuring the absorbance of the sample liquid at 610nm by using an ultraviolet spectrograph, so as to determine the cellulose content according to the prepared standard curve. The method provides a reliable, accurate and repeatable method for quantifying cellulose in plant tissues.