475 results about "Potassium ferrocyanide" patented technology

A fire-extinguishing aerosol not generating harmful substance for electric equipment (computer, communication equipment, electric generator, etc) is prepared from oxidant (strontium nitrate or strontium nitrate / potassium nitrate), reducer (guanidine nitrate or dicyandiamide) and modifier (potassium ferrocyanide, aluminium powder, carbon powder and phenolic resin). After it is ignited by sensor, alot of fire-extinguishing particles are generated to cover on the object to be protected while the inert gas is generated for extinguishing fire.

The invention relates to a preparing method for ferrocyanide with high load / silica hybrid material, belonging to a preparing method for radionuclide ion absorbing material. The method uses the salt solution with metal ion such as Mn, Sn, Ti, Fe, and Ni so on to react with potassium (sodium) ferrocyanide so as to obtain nanometer particle of ferrocyannide. The particle is fixed by silica solution in water system or is fixed by polymerization siloxane in organic solvent and proper inorganic acid, organic amine or amine water is added to obtain hybrid gel. The hybrid gel is dried, rubbed and screened to obtain ferrocyanide with high load / silica hybrid material. The high load of the material is high and the absorption to nuclide ion is strong. In addition, the material intensity can satisfy the demand of packed bed. The particle diameter can be controlled so as to avoid the problem that the water resistance of bed layer generated by ferrocyanide used alone is overlarge.

A new prophylactic mixture is prepared for the effective decorporation of *Cs, *Sr, *I from affected subjects in the event of an accidental release of the radioisotopes in the environment due to any nuclear accident. The prophylactic mixture comprising: 1) Calcium Potassium Ferrocyanide [CaK2Fe(CN)6] 2) Calcium Iodate, and 3) Calcium Carbonate, can be formulated in the form of a single tablet, capsule or suspension for easy administration to the radiation affected subjects in cases of emergency or nuclear fallout. Also claimed are the compound calcium potassium ferrocyanide (CaK2Fe(CN)6) and the use thereof for decorporation of *Cs in subjects affected by nuclear radiation.

The invention relates to a low-toxicity and environmentally friendly gold and silver oredressing additive as well as a preparation method and application thereof. The main raw materials of the additive comprise sodium hydroxide, sodium carbonate, urea and potassium ferrocyanide. The preparation method comprises the following steps of: heating the sodium hydroxide, the sodium carbonate, the urea and the potassium ferrocyanide to 600-1,000 DEG C, and after the materials reach a molten state, continuing to preserve heat for 1-2 hours; directly cooling to normal temperature; and demoulding to obtain a nubby gold and silver oredressing additive. The product of the invention can be widely applied to producing noble metal mines, such as soaking, core spraying, and the like of gold oxide mines, silver oxide mines, copper oxide mines, and also can be used for industrial production industries of electroplating, and the like for replacing highly toxic sodium cyanide chemicals. Compared with other non-toxic sodium cyanide drugs, the additive provided by the invention has the advantages of good effect, stable drug properties, environmental friendliness, lower cost, and the like.

The invention discloses the production method of an environmentally-friendly noble metal mineral processing reagent. The method comprises the following steps: putting potassium ferrocyanide and urea after being mixed into a reactor; adding a pH regulator during the slow temperature rise process; heating to the molten state; taking a small amount of molten material detection samples, cooling and dissolving into water; measuring the pH value, enabling the molten material pH value to be 8-14; keeping the molten temperature for 5-60 minutes; and cooling to the normal temperature, thus the environmentally-friendly noble metal mineral processing reagent is obtained. The product obtained from the invention can be widely applied to the production of noble metal mine, such as the soaking, core spray of gold oxide ores, silver oxide ores and copper oxide ores, also can be used in industrial production industries such as electroplating, and used as medicaments for replacing toxic Cymag; and compared with all the other non-toxic or low-toxicity mineral processing reagents, the noble metal mineral processing reagent has the advantages of good effect, stable drug property, environmentally-friendly product, simple production method, low cost and the like.

A fire-extinguishing aerosol not generating harmful substance for electric equipment (computer, communication equipment, electric generator, etc) is prepared from oxidant (strontium nitrate or strontium nitrate / potassium nitrate), reducer (guanidine nitrate or dicyandiamide) and modifier (potassium ferrocyanide, aluminium powder, carbon powder and phenolic resin). After it is ignited by sensor, a lot of fire-extinguishing particles are generated to cover on the object to be protected while the inert gas is generated for extinguishing fire.

The invention discloses a micron-grade magnetic core coated ferrocyanide adsorbent for removing Cs ions in radioactive wastewater and a preparation method thereof. The adsorbent takes magnetic Fe3O4 as a core, the surface is coated with a dense SiO2 single layer serving as a protective layer, and an active component is metal ion stabilized potassium ferrocyanide coated on the outer layer, wherein stabilized metal ions comprise Ti, Zn, Cu, Ni, Co, and Zr. The particle size of the adsorbent is 0.2-5 μm, the adsorbent in the outermost layer is conductive to improving the adsorption efficiency for Cs+ ions, and an external magnetic field is adopted for realizing solid-liquid phase separation. The preparation method comprises the following steps: coating a hydrated metal oxide of Ti, Zr or Co, Ni, Cu or Zn on the surface of Fe3O4SiO2 to form a composite magnetic material, wherein the hydrated oxide performs hydroxyl polymerization reaction with the surface of SiO2 to produce M—O—Si bonds to improve the bonding strength between M and the surface of SiO2; and finally reacting the composite magnetic material with a potassium ferrocyanide solution to form the required composite adsorbent, wherein the metal ions M achieve the effects of stabilizing the ferrocyanide and also achieve a bridge effect for bonding the ferrocyanide and the composite magnetic material together.

The invention discloses a positive electrode material for a potassium ion battery and a preparation method thereof, and the potassium ion battery. The positive electrode material has a chemical formula of K<x>P[R(CN)<6>], wherein x is no less than 0 and no more than 2, P is a transition metal ion, and R is Fe<2+> or Fe<3+>. The preparation method comprises the following steps: dissolving potassium ferricyanide or potassium ferrocyanide and a transition metal salt to prepare a uniform solution; then carrying out a hydrothermal reaction; separating a precipitate produced in the hydrothermal reaction; and carrying out washing and vacuum drying so as to obtain the positive electrode material. The preparation method in the invention is simple in process, easy to operate, low in cost for required raw materials and suitable for large-scale industrial production. The prepared positive electrode material has an open three-dimensional network frame structure, and great interstitial sites allow potassium ions to shuttle and to be stored, so the potassium ion battery assembled from the positive electrode material has high discharge capacity, long cycle life, and high energy density and power density.

The invention relates to a method for quickly determining the content of additive of a plurality of types in food. An adopted technical scheme is as follows: a solid sample is accurately weighed into a centrifuge tube, petroleum ether or n-hexane is additionally arranged to become homogenate, and supernatant fluid is removed by centrifugation; after the petroleum ether or the n-hexane in the residue are volatilized, the mixed solvent of ethanol, ammonia and water is additionally arranged, ultrasonic extraction is carried out, and the supernatant fluid is obtained by centrifugation as sample liquid for testing; the sample liquid for testing is adopted, potassium ferrocyanide solution and zinc acetate solution are additionally arranged, the mixture is mixed uniformly and centrifuged; the supernatant fluid is concentrated in water bath at 60DEG C to 100DEG C; concentrated solution is transferred to a measuring flask with water; the pH value is regulated to 5 to 7, water is additionally arranged to fix the capacity to a scale; the mixture is mixed uniformly, is filtered by a 0.45mum microfiltration membrane and arranged in a sample bottle as sample liquid; and the sample liquid is tested in a liquid chromatograph by gradient elution under variable wavelengths. According to the invention, the method for quickly determining the content of additive of a plurality of types in food is simple and easy, has high precision, high accuracy, high sensitivity, has the recovery rate being above 80 percent, and is used for determining the content of additive of a plurality of types in food at the same time.

The invention discloses a FeS nano-material and a preparation method thereof. The FeS nano-material has a sheet structure, wherein the thickness of a sheet is 20-100 nanometers, and the length of the sheet is 0.2-5 microns. The preparation method comprises the steps of (1) dissolving potassium ferrocyanide and sodium sulfide into water, then adding a surfactant, and uniformly mixing; (2) reacting for 3-50 hours under hydrothermal conditions at 140-220 DEG C, and naturally cooling to room temperature; (3) centrifuging, washing and drying an obtained product to obtain a sheet FeS capacitor electrode material. The FeS nano-material disclosed by the invention is simple and efficient, and is suitable for large-scale production; a prepared super-capacitor material has a relatively large specific surface area, relatively high specific capacitance and potential application values.

The invention discloses prussian blue nano-scale hollow olivary microballoons, and belongs to the technical field of prussian blue materials. A preparation method of the prussian blue nano-scale hollow olivary microballoons comprises the following steps that 1, acrylamide as a monomer, N,N'-methylenebisacrylamide as a cross-linking agent, ammonium persulfate as an initiator and ethanol as a solvent are prepared into crosslinked polyacrylamide hydrogel microballoons by a dispersion polymerization technology; 2, hydrogel microballoon / ethanol suspending liquid is added with a Fe<3+> salt aqueoussolution; 3 the mixed solution obtained by the step 2 is stirred violently for one night so that the crosslinked polyacrylamide hydrogel microballoons swelled by Fe<3+> deform; 4, a potassium ferrocyanide aqueous solution is added dropwisely into the mixed solution treated by the step 3 to form prussian blue shells; and 5, the solvent is removed so that the prussian blue nano-scale hollow olivarymicroballoons are obtained. The preparation method of the prussian blue nano-scale hollow olivary microballoons has the advantages of simple operation, low cost, good adaptability for large-scale production, and controllability of microballoon sizes. The prussian blue nano-scale hollow olivary microballoons have nano-scale short axis sizes and micron-scale long axis sizes, and can be utilized widely for drug slow release, sensors, electrode materials and the like.

The invention discloses a preparation method of a prussian blue analogue nano-material and a use of the prussian blue analogue nano-material in a sodium-ion battery. The preparation method at least utilizes a metal M-containing salt and potassium ferrocyanide as raw materials and a coprecipitation method to prepare a prussian blue analogue nano-material. The prussian blue analogue nano-material has a chemical formula of MHCNFe, wherein metal M represents at least one of Ni, Cu, Fe and Co. The preparation method has simple processes, utilizes cheap raw materials and is suitable for large scale industrial production. The prussian blue analogue nano-material has uniform nanoscale and grain sizes, is used as a sodium-ion battery negative electrode active material and has high cycling stability.

The invention discloses a vacuum potassium carbonate method for utilizing coke oven coal gas desulphurization and decyanation waste liquid recycling as a resource. The method is also suitable to be used in other waste liquids containing high concentration cyanide and sulfide. According to the method, cyanide and sulfide are simultaneously precipitated; the precipitate is separated by centrifugation; the waste liquid processed from desulphurization and decyanation is processed through pH regulation and coagulant dosing; the processed waste liquid is discharged into a carbonization wastewater biochemical treatment system, and is treated; ferrocyanide precipitate is subject to a reaction with added lye in a high temperature, and is converted into potassium ferrocyanide; potassium ferrocyanide is disoluted, and is separated by centrifugation, such that potassium ferrocyanide mother liquor is obtained; potassium ferrocyanide mother liquor is cooled and crystallized, such that potassium ferrocyanide product is obtained. The method has advantages of simple equipment and convenient operation. With the method, simultaneous desulphurization and decyanation can be realized, requirements of subsequent treatments are satisfied, the wastes are utilized as resources, and economic benefits are brought in.

The invention provides a preparation method of potassium titanium hexacyanoferrate adopting tiny ball-shaped silicagel as carrier, which relates to a preparation method of high specific surface potassium titanium hexacyanoferrate adopting tiny ball-shaped silicagel as carrier. The method is that fashioned porous tiny ball-shaped silicagel under the protection of nitrogen and in the condition of heating and refluxing reacts with organic solvent solution of tetrabutyl titanate. The acquired tiny ball-shaped silicagel loaded with unformed titanium dioxide is dried, dipped in hydrochloric acid solution of kalium ferrocyanatum and then reacting for 12-24h to acquire the high specific surface potassium titanium hexacyanoferrate by adopting tiny the ball-shaped silicagel as carrier. Potassium titanium hexacyanoferrate in the material has adjustable loading amount, good adsorptivity to nuclides, high specific surface, good particle sphericility and solidity, and avoids over-limit moisture resistance of bed layer caused by exclusive use of potassium titanium hexacyanoferrate particles; moreover, owing to existence of Ti-O-Si covalent bond, potassium titanium hexacyanoferrate particles and tiny ball-shaped silicagel can link closely, and do not lose easily during the waste water disposal.

The invention relates to a manganese dioxide / ferric oxide nanometer composite material as well as a preparation method and application thereof, and belongs to a preparation technology and application field of inorganic matter composite materials. The structure of the composite material is characterized by utilizing a manganese dioxide nanometer bar as main body and covering nanometer ferric oxide granules on the surface of the manganese dioxide nanometer bar, wherein the composite material is prepared by utilizing potassium ferrocyanide and potassium permanganate as raw materials, and performing hydro-thermal synthesis, solid-liquid separation and drying steps on the raw materials, and the prepared inorganic nanometer composite material has excellent supercapacitor property. The preparation method of manganese dioxide / ferric oxide nanometer composite material provided by the invention is simple in structure and low in cost, and no dispersing agent or template is added; furthermore, the obtained manganese dioxide / ferric oxide nanometer composite material has the advantages of strong controllability, excellent supercapacitor property, and the like, so that the manganese dioxide / ferric oxide nanometer composite material has brilliant industrial application prospect.

The invention provides preparation of a Prussian blue photo-Fenton catalyst; ferric trichloride, ferric nitrate, ferric sulfate or ammonium ferrous sulfate, potassium ferricyanide, and potassium ferrocyanide are used as raw materials, and are dissolved in ultrapure water respectively to prepare a solution containing iron ions and ferricyanide ions; molecular sieve, kaolin or construction waste are used as carriers, and Prussian blue is fixed on the carriers to obtain fixed Prussian blue photo-Fenton catalyst. The invention also provides a method for degrading organic pollutants by the Prussian blue photo-Fenton catalyst, which comprises mixing of the prepared photo-Fenton catalyst with hydrogen peroxide under a light condition to degrade organic simulated pollutants. The method of the invention is simple and practical; the catalyst is suitable for recycle, can both effectively remove chroma of polluted water, and reduce COD of the polluted water.

The invention relates to a silicone rubber chemical copper plating process, which belongs to the chemical copper plating process. The process is as follows: put the silicone rubber in a tri-alkali solution prepared by sodium hydroxide, sodium carbonate and trisodium phosphate, remove oil, and then wash with water; put it in hydrochloric acid solution to roughen, and wash with water; Soak and sensitize the silicone rubber with a solution prepared with hydrochloric acid solution, the pH value is 0.5-1.9, and wash with water; soak and activate the silicone rubber with a solution prepared with silver nitrate and ammonia water, and wash with water; add sulfuric acid Electroless copper plating is carried out in the copper plating solution, the pH value of the plating solution is required to be 12-13, and the copper plating product is obtained; the plating solution is composed of copper sulfate, formaldehyde, disodium edetate, potassium ferrocyanide and Dilute solution of sodium hydroxide. Advantages: 1. The electroless plating equipment is simple and cost-saving. 2. The copper plating layer on the surface of the silicone rubber is uniform and dense with high strength. 3. The micro-actuator with silicone rubber as the driving body has good flexibility, corrosion resistance and working stability. It can be divided into required shapes within a certain size range, and can work stably in wet and dry environments. .

The invention discloses Prussian blue and Prussian blue analogue nanosheet film materials and an in-situ preparation method thereof. A substrate is modified with two high-molecular polymers with opposite charges, namely PAH (poly allylamine hydrochloride) and PSS (sodium polystyrene sulfonate), and Prussian blue or Prussian blue analogue square nanosheets are synthesized in situ on the modified substrate with metal ionic salt and potassium ferrocyanide as raw materials. A test of a prepared nanosheet film through ultraviolet-visible spectroscopy, a scanning electron microscope and a transmission electron microscope proves that the nanosheets have controllable size and are uniformly dispersed. The growth direction of the nanosheets is limited by the porous network of the high-molecular polymers, so that the nanosheets are square or rectangular, water is used as a solvent in the whole preparation process of the film and is harmless to the environment, the preparation process is simple and feasible, the cost is low, equipment is simple, the film materials with different kinds of functionality are obtained by changing the variety of simple ions, and the in-situ preparation method has important application value in the field of material preparation.

A preparation method for ferrocyanide zirconium Kalium taking bead silica gel as carrier relates to the preparation method for ferrocyanide zirconium Kalium with high specific surface and taking the bead silica gel as the carrier. In the method, fashioned porous bead silica gel react with the solution of zirconium oxychloride under the condition of heating and refluxing, acquired bead silica gel loaded with amorphous zirconium dioxide is dried and then dipped in the hydrochloric acid solution of yellow potassium ferrocyanide for reaction under stirring for 12-24 hours, thus the hybrid material of ferrocyanide zirconium Kalium with high specific surface and taking bead silica gel as the carrier is obtained. The load of ferrocyanide of the material can be adjusted and the material has strong adsorption capability for nuclide ion, high specific surface, good particle degree of sphericity, and being uneasy to break, which avoids the problem of oversized bed water resistance caused by using ferrocyanide zirconium Kalium particles separately; besides, owing to the existence of Zr-O-Si covalent bond, nano ferrocyanide zirconium Kalium particles can closely combine with the bead silica-gel, thus being uneasy to run away in the process of waste water treatment.

This invention relates to a quick test reagent box and its application of nitrite composed of a reaction post, colorimetric cylinder, 1-naphthol, sulfanilic acid hydrochloric acid solution, potassium ferrocyanide, zine acetate, borax saturated solution and a comparison card. The test method includes: preparing a sample process fluid to be processed in chromogenic reaction to compare with the comparison card and determine the content of nitrite in the sample to judge if it has exceeded the target by transformation, which can semiquantitatively test nitrite in foodstuff and the lowest detection limit is 0.1mg / kg.

The invention relates to a method for removing thallium from wastewater, which can be used for removing thallium from thallium-containing wastewater, and belongs to the technical field of environmental protection. The method comprises the following steps: adding a reducing agent into the wastewater to reduce trivalent thallium in the wastewater into univalent thallium under a sufficient stirring condition, sufficiently mixing a potassium ferrocyanide solution and an excessive amount of ferric trichloride solution to obtain a mixture of Prussian blue, ferric trichloride and water, adding the mixture into the wastewater, adding a ferric coagulant solution, and performing stirring and solid-liquid separation to separate thallium in a solid phase from a water body, namely remove the thallium from the wastewater. The method has the characteristics of low thallium removal cost, simple thallium removal process, no secondary pollution and the like, and is also very suitable for thallium removal treatment of thallium-containing wastewater with relatively high COD.

The invention relates to a method for detecting content of fructooligosaccharide in infant formula milk rice flour. The method comprises the following steps: accurately weighting a sample; placing the sample into a volumetric flask; adding hot water for dissolving; mixing uniformly; ultrasonically shaking; cooling to room temperature; accurately adding a potassium ferrocyanide solution and a zinc acetate solution, shaking and uniformly mixing, adding water for achieving a constant volume, and uniformly shaking; standing; filtering by using filter paper; accurately transferring supernate to the volumetric flask until constant volume is achieved by using acetonitrile; shaking and uniformly mixing; filtering through a 0.45 micron organic filter film; performing HPLC (High Performance Liquid Chromatography) measuring and quantifying according to an external standard method, namely, firstly, preparing a standard working solution and respectively injecting the standard working solution into the HPLC, measuring a corresponding peak area and drawing a standard curve, then injecting the prepared sample solution into the HPLC, measuring the corresponding peak area and quantifying the sample on the basis of the standard curve, thereby obtaining the concentration of the sample solution; and calculating the percentage of the content of fructooligosaccharide according to a formula. The method has the advantages of convenience, high speed, accuracy and the like.

The invention relates to a stable kit for measuring NEFA (non-esterified fatty acid) through an enzymic method. The kit comprises two separate liquid reagents, namely, a reagent 1 and a reagent 2 which are respectively placed, and is good in stability and anti-interference performance. The enzymic method is adopted to measure NEFA, and the method is easy, convenient and easy to operate. According to the kit, novel chromogen is selected, and anti-interference agents such as ascorbic acid oxidase and potassium ferrocyanide are added into the formula at the same time, so that the reagent has the characteristics of being high in sensitivity and anti-interference performance; a liquid stabilization technology is adopted, and a series of special stabilizers, chelating agents and enzymatic protective agents are added, so that the reagent is good in stability, and can be widely applied to most semi / full automatic biochemical analyzers, and used for monitoring human body fat metabolic status, lipid level, and the like, and clinical popularization is facilitated.

The invention discloses a prussian-blue derivative Cd2[Fe(CN)6] nanorod and a preparation method thereof. The preparation method for the Cd2[Fe(CN)6] nanorod comprises: firstly adding proper amount of potassium ferrocyanide, polyethylene glycol (PEG-400), a cadmium salt and deionized water into a hydrothermal reaction kettle core, putting into a baking oven and performing 120 DEG C-180 DEG C constant-temperature reaction, and naturally cooling to room temperature after the reaction is finished; and performing centrifugation washing and drying on the prepared product, so as to prepare the Cd2[Fe(CN)6] nanorod. After the prepared Cd2[Fe(CN)6] powder is tested by an X-ray diffractometer and a scanning electron microscope, Cd2[Fe(CN)6] is a nanorod, is uniform in particle size distribution, and can be used as a material used for making electrochromic devices and a secondary battery electrode material.

The invention relates to a method for synthesizing Alpha-iron oxide red nanocrystalline of different shapes by hydrothermal control, belonging to the technical field of inorganic nano material preparation technology. In the invention, water is taken as a solvent, yellow potassium ferrocyanide is dissolved in water, and hydrogen peroxide is added as an oxidant, the ion concentration of hexacyanoferrate is controlled within the range of 0.01-1mol / L, the volume ratio between water and hydrogen peroxide is 0-10:1, and precursor solution is obtained. Then, the precursor is put in a hermetic reaction kettle lined with polytetrafluoroethylene for 0.5-48 hours of crystallization at the temperature of 100-180 DEG C to obtain the Alpha-iron oxide red nanocrystalline. The Alpha-iron oxide red synthesized by the method is uniform in size distribution, controllable in shape, low in cost, simple in equipment, safe and easy in operation, excellent in technique repetition and stable in product quality, and is suitable for industrial large scale production.

The invention belongs to the technical field of radioelement treatment methods, and particularly relates to a method for removing radiocesium 137 with titanium potassium ferrocyanide spherical particles, which comprises the following steps: adding titanium potassium ferrocyanide spherical particles into a sea water sample containing cesium 137, putting the sea water sample containing cesium 137 in a constant temperature oscillator, and waiting for some time to remove the radiocesium 137. The titanium potassium ferrocyanide spherical particles have high adsorption capacity for cesium, and can not be easily decomposed, and the adsorptive particles can be easily recycled; the particles which adsorb cesium can be converted into oxides to facilitate temporary storage; and the experimental conditions are mild. The saturation adsorption capacity for cesium of the titanium potassium ferrocyanide spherical particles is 0.9-1.3 mmol Cs / g dry composite particles, and the adsorption capacity for radiocesium in the sea water sample containing cesium 137 (the total cesium content is 5-10 times of radiocesium), of which the radiation dose is 2500-75000 Bq / ml, is up to 97% after 8 hours.

The invention belongs to the technical field of a method for preparing a compound ferrous iron cyanide titanium potassium magnetic ball, and in particular relates to the compound ferrous iron cyanide titanium potassium magnetic ball and a preparation method thereof. The method comprises the following steps of: preparing a magnetic ferroferric oxide silicon dioxide microballoon by using a ferroferric oxide magnetic particle with the grain diameter of 0.3-0.8 microns as a core and using tetraethoxysilane as a silicon source; then preparing a magnetic ferroferric oxide silicon dioxide-titanium oxide spherical particle by taking dichloro oxotitanium as a titanium source; and finally, preparing the compound ferrous iron cyanide titanium potassium magnetic ball by using potassium ferrocyanide as a soaking agent. The method has simple steps and is mild in experiment condition; and the grain diameter of the prepared compound ferrous iron cyanide titanium potassium magnetic ball is 0.05-0.2mm, the saturation capacity of absorbed cesium is 1.0 mmolCs / g-1.4 mmolCs / g dry compound particles; and therefore, the method for preparing the compound ferrous iron cyanide titanium potassium magnetic ball has the advantages that the absorption capacity of the ferrous iron cyanide titanium potassium to the cesium is preserved under the mild condition, the analysis is difficult to carry out, and the absorbed particles are easy to recover; and particulate matter of the absorbed cesium can be transformed to oxide to be conveniently stored.

The invention discloses a cobalt-iron bimetallic nitride composite electrocatalyst and a preparation method thereof. The electrocatalyst comprises the components by the mass percentage: 20-52% of ironnitride, 44-26% of cobalt nitride and the balance being carbon cloth. The preparation method comprises the steps: refluxing carbon cloth with concentrated nitric acid, cleaning and drying; preparinga cobalt nitrate aqueous solution, adding the cobalt nitrate aqueous solution into a prepared 2-methylimidazole aqueous solution, uniformly stirring and mixing, adding the treated carbon cloth into the obtained mixed solution, carrying out a reaction at room temperature, cleaning and drying to obtain a ZIF-67 / carbon cloth composite material; adding the ZIF-67 / carbon cloth composite material into aprepared potassium ferrocyanide aqueous solution, carrying out a reaction at room temperature, cleaning and drying, calcining, and cooling to room temperature to obtain the iron nitride / cobalt nitride / carbon cloth composite material. The prepared electrocatalyst can greatly reduce overpotential and Tafel slope, has good electrical conductivity, and can greatly improve the water decomposition andcatalytic oxygen production efficiency of the composite electrocatalyst.

The invention discloses an enzyme-colorimetric method for detecting residual hydrogen peroxide in foods. The enzyme-colorimetric method comprises the following steps of: weighing a sample and adding zinc sulfate and potassium ferrocyanide to precipitate fat and protein; filtering and adjusting the pH (Potential of Hydrogen) value of filtering liquid to 7.6; filtering again and adding a hydrogen peroxide enzyme reagent solution into filtering liquid; enabling the volume to be constant; determining the absorbance at a part of 470nm; and calculating the content of the hydrogen peroxide in the sample. The method disclosed by the invention is simple, fast and accurate and has small interference.

The invention provides a special gold dissolving agent for a gold ore. The special gold dissolving agent is prepared by reacting and mixing carbonate or bicarbonate, hydroxide, permanganate, perchlorate, persulphate, ammonium salt, sodium ferrocyanide or potassium ferrocyanide. The gold dissolving agent has the advantages of rapidly dissolving metal gold, selectively leaching gold from various gold ores, being low in toxicity and the like.