29results about "Chromium trioxide" patented technology

The invention discloses a preparation method and application of a carbon dioxide hydrogenation catalyst, and belongs to the field of hydrogenation catalysis. The vanadium slag is used as a raw material, a leaching solution containing silicon, chromium and vanadium is obtained through sodium salt roasting, an aluminum source is added to remove the silicon element, meanwhile, an ordered mesoporous carbon material is added, and silicon and aluminum elements are converted into an ordered mesoporous composite oxide which is used as a hydrogenation catalyst carrier; an indium salt, a cerium salt and a nickel salt are dissolved in ethanol and mixed with the carrier for isopyknic impregnation to obtain the hydrogenation catalyst; and carrying out chromium and vanadium separation on the silicon-removed leaching solution to obtain chromium sesquioxide and the all-vanadium redox flow battery electrolyte. The catalyst has a regular pore structure, ordered mesopores provide a confinement effect, dispersion and anchoring of active components are facilitated, and the activity of the catalyst is remarkably improved.

The invention provides self-recovery chromium ion doped oxide mechanoluminescence fluorescent powder as well as a preparation method and application thereof. The chemical general formula of the self-recovery mechanoluminescence fluorescent powder is Al2 (1-x) O3: 2xCr < 3 + >, wherein x is equal to 0.3%-5%. The preparation method of the self-recovery mechanoluminescence fluorescent powder comprises the following steps: a, respectively weighing aluminum oxide and chromium oxide according to the molar ratio of each element in the chemical general formula Al2 (1-x) O3: 2xCr < 3 + >; b, grinding and uniformly mixing the weighed raw materials, and firing in air at the temperature of 1300 DEG C for 6 hours; and c, taking out the fired sample, and uniformly grinding to obtain the chromium ion doped oxide mechanoluminescence fluorescent powder. According to the chromium ion doped oxide mechanoluminescence fluorescent powder disclosed by the invention, a measured emission band main peak is located at 694 nm and is located at a biological first window (600-900 nm), and the chromium ion doped oxide mechanoluminescence fluorescent powder is expected to be used as a near-infrared mechanoluminescence biological probe; and the fluorescent powder has the advantages of no need of pre-irradiation and instant self-recovery of luminescence.

The invention discloses a chromium-containing wastewater treatment and recovery treatment line and a recovery treatment method thereof. The ion exchange system is used for carrying out ion exchange adsorption on the hexavalent wastewater; the alkali washing system is used for outputting alkali liquor to the ion exchange system; the washing system is used for outputting washing water to the ion exchange system; the pickling system is used for outputting acid liquor to the ion exchange system; the chromium recovery treatment branch line is used for receiving the hexavalent wastewater of the ion exchange system, mixing the hexavalent wastewater with sulfur powder and alkali liquor to prepare chromium hydroxide, then carrying out filter pressing on the chromium hydroxide, outputting a chromium hydroxide filter cake to the recovery calcination treatment line, and outputting a press filtrate to the press filtrate recovery branch line; the press filtrate recovery branch line is used for recovering sodium thiosulfate from the press filtrate; and the recycling and calcining treatment line is used for calcining the chromium hydroxide filter cake into Cr2O3. According to the scheme, the purposes of micro discharge and even zero discharge of the chromium-containing wastewater are achieved, and the problem that a large amount of chromium-containing hazardous waste sludge is generated by depending on a chemical reduction-precipitation method in traditional chromium-containing wastewater treatment is solved.

The invention provides a method and a system for recovering chromium and aluminum from a waste chromium catalyst. The method comprises the following steps: carrying out alkali fusion reaction on the waste chromium catalyst and sodium hydroxide to obtain alkali fusion clinker; mixing the alkali fusion clinker with water, pulping, leaching, and carrying out solid-liquid separation to obtain a water leaching solution containing Na2CrO4 and NaAlO2 and a filter cake containing Al2O3; adding a barium salt solution or solid into the aqueous extract containing Na2CrO4 and NaAlO2, reacting to generate a BaCrO4 precipitate, and carrying out solid-liquid separation to obtain a BaCrO4 filter cake and a sodium metaaluminate filtrate; reacting the BaCrO4 filter cake with an inorganic acid, and carrying out solid-liquid separation to obtain a chromic acid solution and a barium sulfate precipitate; and adding an acid solution into the sodium metaaluminate filtrate, adjusting the pH value to 7-8, and carrying out solid-liquid separation to obtain an Al (OH) 3 filter cake. According to the method, Cr (III) in the waste catalyst is directionally converted into Cr (VI) through an alkali fusion oxidation process, then the solubility difference of sodium chromate and sodium metaaluminate in an aqueous solution is fully utilized, the high-selectivity separation characteristic of barium chromate precipitation is combined, the chromium-aluminum separation problem is fundamentally solved, and the finally obtained product is excellent in purity.

The present invention discloses a high-strength and tough intracrystalline distributed Cr2O3-CNTs composite phase reinforced Cu-based composite material, as well as its preparation method and application. The method comprises the following steps: subjecting CNTs coated with a Cr(OH)3 coating on the surface to solution-assisted ball milling with Cu powder, then filtering and drying, and then dry-milling with different ball milling parameters for more than two times to mix, and vacuum sintering and hot-rolling the obtained composite powder to obtain a composite material. After sintering and hot rolling, the Cr(OH)3 on the surface of the CNTs will undergo in-situ decomposition in the Cu matrix to form Cr2O3, thereby forming a CNTs-Cr2O3-Cu composite interface with a Cr2O3 transition layer. The strength, hardness, and Young's modulus of the Cu-based composite material with this interface are significantly improved, and the strengthening efficiency of CNTs is also significantly improved. The composite material has broad application prospects in fields requiring high mechanical properties, high thermal conductivity, and high electrical conductivity.

The invention relates to a method for producing low-iron low-silicon high-quality chromium oxide green based on an electromagnetic rotary kiln, which comprises the following steps: continuously or batch-wise feeding raw materials into the electromagnetic rotary kiln, controlling the temperature in the kiln body to be 400-1100 DEG C by adjusting the current and frequency of a coil in sections, and dividing the treatment process of the materials in the kiln into a preheating section, a high-temperature reaction section, a heat preservation section and a cooling section; and staying the materials in the kiln for 3 hours, heating and calcining through heat radiation and heat conduction to generate chromium oxide green, and crushing to obtain a low-iron low-silicon high-purity chromium oxide green product. In the final product, the content of Cr2O3 can reach 99.5% or above, the content of Fe2O3 is smaller than or equal to 0.01%, the content of SiO2 is smaller than or equal to 0.1%, and the content of S is smaller than or equal to 0.003%, all indexes meet high-end application requirements, the process is accurate in control, energy-saving and environment-friendly, the structure of the rotary furnace is simplified, and the maintenance cost is low.

The invention discloses a method for preparing chromic anhydride from a sodium chromate neutral solution, which comprises the following steps: transferring the sodium chromate neutral solution into a storage tank of an anode head tank by using a pump, adjusting the temperature, transferring a sodium hydroxide solution into a storage tank of a cathode head tank, and adjusting the temperature; overflowing the sodium chromate neutral solution after temperature regulation to an anode chamber of an electrolytic bath and then overflowing to an anode circulating tank, and overflowing the sodium hydroxide solution after temperature regulation to a cathode chamber of the electrolytic bath and then overflowing to a cathode circulating tank; electrifying a cathode plate and an anode plate of the electrolytic bath with direct current to start electrolysis; pumping out an anode solution after electrolysis, adding the anode solution into a reaction kettle after evaporation, adding concentrated sulfuric acid, heating and dehydrating, and standing in a clarifier until layering; the upper layer is sodium hydrogen sulfate, and the lower layer is chromic anhydride liquid, cooling and flaking to obtain the high-quality chromic anhydride. The method can effectively shorten the production period, greatly improve the production yield, reduce the labor intensity of workers, avoid high cost of an electrolytic method and avoid a large amount of byproduct chromium-containing sodium hydrogen sulfate of a sulfuric acid method, and is economical and practical.

This invention relates to a method for preparing nano metal oxides and its use. The preparation method involves reacting a low-purity initial alloy containing the target metal element M and Al / Zn with a heated concentrated alkaline solution. Under specific reaction conditions, the initial alloy undergoes intense hydrogen evolution and Al / Zn-removal reaction, resulting in nanoscale fragmentation, followed by shape and composition reconstruction to form nano M oxides. Through further post-treatment, crystalline nano M oxides or modified nano M oxides can be obtained. This method is simple, fast, cost-effective, and suitable for large-scale production. It enables the preparation of nano metal oxides with various crystallinities, which have promising applications in fields including composite materials, catalytic materials, ceramic materials, refractory materials, advanced electronic materials, battery materials, chromogenic materials, wave-absorbing materials, wastewater degradation materials, antimicrobial materials, coatings, pigments, thermal spray materials, and sensors.

The invention relates to a preparation method and application of chromium-doped sodium titanate with high cycle stability, the chromium-doped sodium titanate is formed by solid-phase sintering of Na2CO3, nano TiO2 and Cr2O3, and optimized Cr-Na2Ti3O7 has excellent cycle stability; the preparation method comprises the following steps: taking a certain amount of Na2CO3, nano TiO2 and Cr2O3 in a corresponding proportion, adding a small amount of isopropanol, and carrying out ball milling in a ball milling instrument for 5-8 hours; completely drying in a drying box, and putting the dried product into a tubular furnace; in a closed atmosphere of high-purity argon, carrying out solid-phase sintering for 10-12 hours by adopting a step-by-step calcination method, and naturally cooling to room temperature; when the material is used as a negative electrode of a sodium ion battery, the coordination environment of sodium ions can be changed, an interlayer Ti-O bond is optimized so as to optimize an interlayer structure, the irreversible capacity generated by Na2Ti3O7 in the charge-discharge cycle process is obviously reduced, and the cycle stability and the rate performance of the battery are improved; the preparation method has important significance for developing a high-performance negative electrode material of the sodium-ion battery and improving the performance of the sodium-ion battery.

The utility model discloses a device for reducing the content of hexavalent chromium in chromium oxide green. The device comprises a frame, a starting switch is arranged on the frame, a rotating roller and a first transmission part are arranged at the top of the frame, a feeding opening is formed in the top of the rotating roller, and a cover plate is arranged above the feeding opening; a reducing agent storage bin and a chromium oxide green storage bin are arranged above the rotating roller, a first metering screw is arranged at the bottom of the reducing agent storage bin, a second metering screw is arranged at the bottom of the chromium oxide green storage bin, and discharging ports of the first metering screw and the second metering screw are aligned to a feeding port in the top of the rotating roller; the bottoms of the first metering screw and the second metering screw are connected with the top of the frame through connecting rods. Chromium oxide green and a reducing agent are added into the chromium oxide green storage bin and the reducing agent storage bin respectively, then the first metering screw and the second metering screw are controlled to feed materials in proportion, and after the set reaction time is reached, the materials flow out from a feeding port of the rotating roller rotating continuously and are scraped out through the discharging scraper.

The invention discloses a preparation method of ternary composite doped modified lithium manganate, which comprises the following steps: by taking Li2CO3 as a lithium source, a multivalent manganese oxide mixture as a manganese source and aluminum isopropoxide, magnesium isopropoxide and tetrabutyl titanate as a ternary doping source, preparing precursor powder by a sol-gel method, and then performing segmented sintering to obtain a ternary doped lithium manganate matrix; the preparation method comprises the following steps: preparing a composite coating solution from tert-butyl chromate, tetrabutyl titanate and Y2O3, carrying out fluidized bed spray coating, and carrying out segmented heating and cooling sintering, screening and demagnetizing treatment to obtain a target product. According to the preparation method, the lattice structure is synergistically optimized through a multivalent manganese source and ternary doping, the Cr2O3-TiO2 / Y2O3 composite coating layer can effectively block direct contact between a matrix and an electrolyte, the occurrence probability of interface side reactions is reduced, and the lattice stability and interface performance of the material are remarkably improved in cooperation with process regulation and control. The initial discharge specific capacity of the product is excellent, the high-temperature cycle and storage stability are greatly improved, and the manganese ion dissolving amount and the interface impedance are effectively reduced.

To provide a reducing agent that has high conversion efficiency of carbon dioxide to carbon monoxide, and can be used, for example, in a chemical looping method, and a method for producing a gas using the reducing agent.SOLUTION: The reducing agent of the present invention is used in the production of a product gas containing carbon monoxide by bringing a raw material gas containing carbon dioxide into contact with the reducing agent to reduce the carbon dioxide, the reducing agent comprising an oxygen carrier having oxygen ionic conductivity and a basic oxide supported on the oxygen carrier. The basic oxide preferably contains at least one selected from the group consisting of lithium (Li), sodium (Na), potassium (K), magnesium (Mg), manganese (Mn), cobalt (Co), strontium (Sr), and rubidium (Rb).SELECTED DRAWING: None

A method for preparing high-purity chromic oxide and by-product sodium 3-picolinate by recycling chromium-containing waste comprises the following steps: adding chromium-containing waste residues and chromium-containing sodium hydrogen sulfate into water, stirring, adding 3-methylpyridine, stirring to obtain a mixed material, adding the mixed material into a reaction kettle, stirring, and heating for reaction; recovering unreacted azeotrope of 3-methylpyridine and water after the reaction is finished, condensing the recovered material to obtain 3-methylpyridine, returning the 3-methylpyridine, cooling the reaction kettle after the recovery is finished, and pressing the material into a reaction liquid storage tank by using compressed air; filtering the feed liquid in the reaction liquid storage tank to obtain a filtrate and a filter cake, washing and filtering the filter cake to obtain hydrated chromium hydroxide, and recycling the washing liquid as recycled water; and calcining the hydrated chromium hydroxide at high temperature to obtain chromium oxide. The chromium-containing waste is adopted as the raw material, discharge of the chromium-containing waste is reduced, and the method has important economic and environment-friendly significance. The product in the process can be recycled, so that the method is more environment-friendly.

The present invention provides a Cu-Cr-O based pigment having an excellent color characteristic and improved durability. The present invention relates to a Cu-Cr-Zn-O based pigment consisting of a Cu-Cr-O based oxide and Zn derived from zinc oxide added as a modifying oxide and solid-dissolving in the Cu-Cr-O based oxide, in which the oxides have a composition formula of aCuO·bCr2O3·cZnO (mol%) in which 0.1 ≤ c ≤ 5, 45 ≤ a + c ≤ 55, and 45 ≤ b ≤ 55 (a + b + c = 100).

The invention discloses a method for preparing a sodium sulfate solution and chromic oxide of different grades from chromium-containing sodium hydrogen sulfate, which comprises the following steps: calcining the chromium-containing sodium hydrogen sulfate at high temperature to obtain a solid product and a gas product; putting the solid product into a pulping tank, adding water, pulping and dissolving until the solid product is completely dispersed, preparing a feed liquid, and carrying out filter pressing to obtain a primary filter-pressed filter cake and an acidic solution; adding alkali into the acidic solution for neutralization, preserving heat and curing, and then carrying out filter pressing to obtain a secondary filter-pressed filter cake and a slightly acidic solution; washing and filter-pressing the primary filter-pressed filter cake, and calcining to obtain low-grade chromium sesquioxide; and washing the secondary filter-pressed filter cake, carrying out filter pressing, and calcining to obtain the high-grade chromium sesquioxide. The invention provides the method for efficiently recycling the by-product chromium-containing sodium hydrogen sulfate in the production process of chromic anhydride, the problem of poison of wastes is solved, the process is simple and easy to operate, environmental protection benefits and economic benefits are considered, and the method is suitable for industrial production.

The invention provides a chromium oxide activated boron fuel and a preparation method thereof, the method takes a boron fuel as a carrier, and the method adopts a microwave precipitation method to load chromium oxide particles on the surface of the boron fuel to prepare the chromium oxide activated boron fuel. According to the microwave precipitation method, chromium trichloride and ammonia water are used as raw materials, and the chromium trichloride and the ammonia water react in a microwave synthesis instrument to generate chromium oxide precipitate. The reaction temperature of the microwave precipitation method is 80 DEG C, and the reaction time is 60 minutes. And the particle size of the chromium oxide particles is 1-10nm. The temperature corresponding to the oxidation peak of the chromium oxide activated boron fuel is 624-625 DEG C; the ignition delay time ranges from 36 ms to 38 ms. According to the Cr2O3 / B activated fuel prepared by the invention, Cr2O3 is particles on the surface of the boron fuel, Cr2O3 is highly dispersed on the surface of the B fuel and is uniformly loaded on the surface of the boron fuel, and the loading capacity is accurate and adjustable.

The invention provides a preparation method of a metal oxide material, the metal oxide material and a photoelectric device.The preparation method of the metal oxide material comprises the steps that dispersion liquid containing metal oxide is provided, the dispersion liquid and acid are mixed, and a first system is obtained; performing ultraviolet radiation treatment on the first reaction system to obtain a second system; and the second system is subjected to solid-liquid separation treatment, and the collected solid is the metal oxide material, so that the size consistency of the metal oxide material is improved.

The present invention relates to the technical field of sludge treatment, and specifically discloses a resource recovery method and recovery device for chromium-containing electroplating sludge. The chromium-containing electroplating sludge is directly mixed with water, and then a disintegrating agent is added for disintegration. The slurry is then sheared by a homogenizer at high pressure to promote slurry refinement. Liquid caustic soda, a catalyst, and an oxidizing agent are then added. Under a certain temperature and pressure, the trivalent chromium in the chromium-containing electroplating sludge is oxidized to a sodium chromate solution containing hexavalent chromium, with an oxidation rate of up to 99.9%. A low-value mixed reducing agent is added, and under a certain temperature and pressure, the sodium chromate is reduced to chromium oxide hydrate. The chromium oxide hydrate is calcined to obtain chromium oxide green. The resulting mother liquor is used to produce barium sulfate and sodium carbonate, thereby realizing resource utilization of the chromium-containing electroplating sludge. The present invention can improve the metal recovery rate of the chromium-containing electroplating sludge, and can not only recover chromium, nickel, copper, and iron in the sludge, but also recover high-purity sodium carbonate and barium sulfate.

The invention discloses a method for separating vanadium and chromium ions in vanadium slag water leaching liquid, and belongs to the technical field of metallurgical chemical engineering, the method comprises the following steps: by taking the water leaching liquid obtained after sodium salt roasting of vanadium slag as raw material liquid, removing silicon, adjusting pH, adding a reducing agent to selectively reduce hexavalent chromium into trivalent chromium, and then adsorbing chromium in the solution by using cation exchange resin, thereby obtaining the vanadium and chromium ions in the vanadium slag water leaching liquid. Vanadium in the solution is subjected to vanadium precipitation to obtain vanadium pentoxide, then chromium on the resin is desorbed with an acid solution, the pH of the desorption solution is adjusted to form chromium precipitate, and chromium trioxide is obtained after roasting. According to the method, through collaborative innovation of selective reduction, strong acid cation exchange directional adsorption and an organic solvent-free process, the problems of incomplete separation of vanadium and chromium, low recovery rate and high cost in a traditional method are solved, efficient recovery of high-purity vanadium and chromium products is realized, and the method has both environmental protection property and economical efficiency.

The present disclosure relates to a chiral metal oxide nanostructure and a method of preparing the same.

This invention employs an Al-rich or Zn-rich intermetallic compound containing a doped noble metal element as a precursor, and reacts the intermetallic compound containing the doped noble metal element with the base solution at atmospheric pressure near the boiling point of the base solution, thereby achieving high-efficiency atmospheric-pressure production of nanometal oxides doped with noble metal nanoparticles of different crystalline properties. Simultaneously, a method for producing noble metal nanoparticles based on the nanometal oxides doped with noble metal nanoparticles is also provided. The production method of this invention is characterized by a simple process, easy operation, high efficiency, and low cost, and the produced products can be used in a wide range of applications, such as composite materials, catalyst materials, ceramic materials, refractory materials, advanced electronic materials, battery materials, discoloration materials, wave-absorbing materials, wastewater decomposition materials, sterilization materials, paints, pigments, thermal spray materials, and sensors.

The application discloses a method for cleaning and reprocessing and resource utilization of waste chrome tanning scraps and application thereof, and belongs to the technical field of solid waste resource utilization. The method is to use a citric acid-EDTA composite cleaning agent to clean and process the leather scraps and separate chromium; a composite enzyme preparation is used to enzymatically hydrolyze the chromium-removed leather residue under high temperature and high pressure to extract collagen; the chromium-containing filtrate is alkalized, precipitated and calcined to recover chromium trioxide; and finally, the enzymatically hydrolyzed residue is blended with a thermoplastic polymer to extrude plastic fillers. The application realizes efficient recovery of chromium and efficient extraction of collagen, and the process is clean and environmentally friendly, without toxic and harmful emissions, so that full-component and high-value utilization of the waste is achieved.

The invention discloses a method for preparing a chromic oxide and sodium sulfate solution from chromium-containing sodium hydrogen sulfate, which comprises the following steps: preparing chromium-containing sodium hydrogen sulfate into a sheet by a sheet preparation machine, and calcining to obtain a calcined product; adding the calcined product into water to prepare a feed liquid, then adding sodium hydroxide for neutralization to prepare a mixed solution of chromic hydroxide and sodium sulfate, carrying out heat preservation and curing, then carrying out filter pressing to obtain a filter cake, then washing and carrying out filter pressing on the filter cake to obtain a chromic hydroxide filter cake, and carrying out filter pressing to obtain a filtrate which is a sodium sulfate solution; and calcining the chromium hydroxide filter cake to obtain chromium sesquioxide. According to the resource utilization method for the by-product chromium-containing sodium hydrogen sulfate in the chromic anhydride production process, the chromium-containing sodium hydrogen sulfate is converted into chromium sesquioxide and sodium sulfate solutions with high additional values, the problem of poison of waste is solved, and efficient recycling of chromium and sodium hydrogen sulfate is achieved; in addition, the method is simple in process, low in cost and suitable for industrial production.

The application provides a perovskite nitride synthesized based on a molten salt assisted template method and a preparation method and application thereof, and the chemical composition of the perovskite nitride synthesized based on the molten salt assisted template method comprises CaTaO2N, and belongs to the technical field of photocatalytic materials. The CaTaO2N prepared by the method has a unique nano-frame crystal structure, and the photocatalytic material can fully decompose pure water and produce hydrogen under visible light.

This application utilizes intermetallic compounds rich in Al or Zn, doped with noble metal elements in a solid solution, as precursors. At atmospheric pressure and near the boiling point of an alkaline solution, the intermetallic compounds doped with noble metal elements are reacted with the alkaline solution, enabling the efficient preparation of nano metal oxides with noble metal nanoparticle doping and varying degrees of crystallinity under atmospheric conditions. Additionally, based on the nano metal oxides doped with noble metal nanoparticles, this application provides a method for preparing noble metal nanoparticles. The preparation method described in this application is characterized by its simplicity, ease of operation, high efficiency, and low cost. The resulting products have broad applications in fields such as composite materials, catalytic materials, ceramic materials, refractory materials, advanced electronic materials, battery materials, chromogenic materials, microwave-absorbing materials, wastewater degradation materials, antibacterial materials, coatings, pigments, thermal spray materials, and sensors.

The invention relates to the technical field of preparation of high-purity chromium metal, in particular to a preparation method of high-purity chromium metal. The method comprises the following steps: (1) preparing a chromium trichloride solution; (2) purification: purifying the prepared chromium trichloride solution by an ion exchange method; (3) performing spray pyrolysis to prepare chromium sesquioxide; (4) gas-solid separation; and (5) chromium sesquioxide is reduced to prepare high-purity metal chromium. The method comprises the following steps: preparing a chromium trichloride solution by using metal chromium of 3N5, purifying the chromium trichloride solution by using an ion exchange method to remove heavy metal impurities in the chromium trichloride solution, and performing spray pyrolysis on the purified chromium trichloride solution to prepare high-purity chromium sesquioxide powder. Metal and interstitial element impurities such as oxygen, nitrogen and the like and low-melting-point metal impurities in the chromium sesquioxide are removed through a reduction method, and the purity of the prepared high-purity metal chromium reaches 99.999% or above. The preparation method is simple in process and few in control parameters, and the prepared chromium metal is high in purity.

The invention discloses an in-situ heterogeneous nucleation supported catalyst as well as a preparation method and application thereof. The method comprises the following steps: firstly, precipitating a conductive metal oxide carrier precursor at a low pH value of 6.0-10; a solution containing two or more metal cations of nickel, iron, cobalt, chromium, manganese, copper and zinc is precipitated on the surface of the carrier under the condition that the pH is equal to 10-14, and high-dispersion transition metal-based active nanoparticles are formed on the carrier through in-situ heterogeneous nucleation; and finally, aging, washing, drying and carrying out heat treatment to obtain the catalyst. According to the method, a particle-carrier structure with uniformly loaded active particles and a clear interface is successfully constructed through fractional precipitation and interface nucleation control, a solid solution formed by traditional coprecipitation is effectively avoided, and maximum exposure and strong interface bonding of active sites are realized. The prepared catalyst shows high activity, low overpotential and excellent long-term operation stability in water electrolysis oxygen evolution reaction, and is simple in process, good in reproducibility and suitable for large-scale production.

The invention provides a method for preparing chromium sesquioxide powder by taking chromium-containing wastewater as a raw material, and belongs to the field of sewage treatment. The method for preparing the chromium sesquioxide powder by taking the chromium-containing wastewater as the raw material comprises the following steps: mixing the chromium-containing wastewater and a pH regulator, carrying out precipitation reaction, and then carrying out solid-liquid separation to obtain a dichromate solution; the pH value of the precipitation reaction is 2-4; after the dichromate solution flows through weak base anion resin to be treated, hexavalent chromium adsorption saturated resin is obtained; ammonia water is adopted to analyze the hexavalent chromium adsorption saturated resin, and a mixed solution is obtained; the mixed solution is a mixed solution of ammonium chromate and ammonium dichromate; the mixed solution is sequentially subjected to evaporation concentration, spray drying and calcination, and chromium sesquioxide powder is obtained. The method provided by the invention is simple in preparation steps, the obtained chromium sesquioxide powder is uniform in particle size, the purity can reach 99.6%, and the purity requirement of pigment-grade chromium sesquioxide is met.

A process of chemical cleavage of leather or skins containing chromium using sodium, potassium or calcium methylates (CH3O−) or ethylates (CH3CH2O−), producing chromium hydroxide (green paste), ammonium sulfate and liquid fertilizer. The chromium trioxide III (Cr2O3) obtained was used in the production of Fe—Cr alloy. The liquid fertilizer was applied to strawberry, violet and acerola crops, and can be applied to other types of crops. The fertilizer is also compatible with pesticides, being able to compose a composition containing fertilizer and pesticide or even used to obtain products containing fertilizers and pesticides, which allow application in a single step, exempting the process in the field A solid NPK fertilizer formulation obtained by combining N recovered from waste and homogeneously mixed with K and P salts.