5508 results about "Salt solution" patented technology

The invention provides a method for enhancing interface bonding and corrosion resistance of a basalt fiber composite material, and belongs to the field of fiber surface modification chemical methods. The method is realized through the following steps: firstly, treating basalt fibers by utilizing an organic solvent through high-temperature reflux to prepare desized basalt fibers; then, the desized basalt fibers are immersed in a dopamine solution to be subjected to auto-polymerization, and basalt fibers with a polydopamine coating are prepared; sequentially immersing the basalt fiber coated with the polydopamine into a zinc salt solution and a 2-methylimidazole solution, so as to prepare a ZIF-8 modified basalt fiber; and finally, mixing the ZIF-8 modified basalt fiber with resin through electrostatic coating, and molding by adopting a segmented hot-pressing method to obtain the basalt fiber composite material. According to the method, a composite structure formed by the synergistic effect of a dopamine self-polymerization layer and ZIF-8 is introduced into the surface of the basalt fiber, so that the interface bonding force between the fiber and resin and the corrosion resistance of the composite material are greatly enhanced.

The invention discloses a lithium manganese iron phosphate positive electrode material with a core-shell structure, which is prepared by the following steps: mixing a manganese source, an iron source, a phosphorus source, lithium carbonate and a carbon source, grinding and drying to prepare a pre-sintered material; then carrying out gas crushing on the pre-sintered material to obtain a pre-gas crushed material, and carrying out heat preservation at the temperature of 200-600 DEG C; putting the pre-gas crushed material subjected to heat preservation into an iron salt solution for quenching reaction to obtain iron compound coated lithium manganese iron phosphate; and finally, mixing the lithium iron manganese phosphate coated with the iron compound, a lithium source, a phosphorus source and a carbon source, grinding, drying, and carrying out secondary calcination to obtain the lithium iron manganese phosphate material with the core-shell structure. During preparation of the lithium manganese iron phosphate positive electrode material, a lithium manganese iron phosphate pre-sintered body and an iron salt solution are subjected to a quenching reaction to form an iron compound coated lithium manganese iron phosphate pre-sintered body, and then the iron compound coated lithium manganese iron phosphate pre-sintered body and other raw materials of lithium iron phosphate are subjected to a secondary calcination reaction to generate the composite positive electrode material with a core-shell structure. A coating structure is formed, the reaction between manganese and electrolyte is reduced, the dissolution of manganese is inhibited, the Gingtaler effect of manganese is relieved, and the stability of the material is improved; and the material has the advantages of high energy density, high power density, excellent cycle performance and strong core-shell interface bonding force.

The invention belongs to the technical field of CO catalytic oxidation, and particularly discloses a method for synthesizing a CuO / CeO2 catalyst through a rapid fluid mixing method and application thereof.The method comprises the steps that a copper salt solution A and a cerium salt solution B are put into a rapid fluid turbulence mixing reactor, the flow speed is controlled, a catalyst precursor is prepared after product treatment, the catalyst precursor is put into a muffle furnace, air is introduced for calcination, and the catalyst is prepared; and high selectivity and high conversion rate in CO oxidation reaction in a hydrogen-rich environment are realized. The method provided by the invention also improves the traditional MOF synthesis method, adopts water as a solvent, and reduces the synthesis conditions. The prepared catalyst has high conversion rate and selectivity, the CO conversion rate at 90 DEG C reaches 100%, and the corresponding selectivity is 100%.

The invention discloses a method for recovering lithium, nickel cobalt manganese composite hydroxide and aluminum copper powder from a waste ternary lithium ion battery pole piece. The method comprises the following steps: treating waste pole pieces of a ternary plant or a mixture of positive and negative pole pieces by using a Fenton technology, leaching by using a mixed ferric salt solution, and filtering to obtain lithium-containing leachate and slag; adjusting the pH value of the leachate, oxidizing and filtering to obtain a purified solution and ferric hydroxide precipitate, and adding the purified solution and a lithium hydroxide solution into a reactor for coprecipitation to obtain a deeply purified solution and the nickel-cobalt-manganese composite hydroxide. And dissolving the ferric hydroxide precipitate with dilute acid, adding a reducing agent to generate a ferrous salt solution, and returning the ferrous salt solution for Fenton reaction and leaching reaction. And adding the sodium carbonate saturated solution into the deep purification solution, and crystallizing and precipitating to obtain the battery-grade lithium carbonate. And performing hydrodynamic screening on the leaching residues to obtain an aluminum-copper mixture and graphite residues, and performing grinding and specific gravity separation on the aluminum-copper mixture to obtain high-purity aluminum powder and copper powder. According to the method, the iron salt is directly leached from the pole piece, the used iron salt can be recycled, and the method is suitable for large-scale recovery of the waste ternary lithium ion battery.

The invention belongs to the technical field of catalysts, and particularly relates to an alumina-based catalyst for anthraquinone hydrogenation and a preparation method thereof.The preparation method comprises the following steps that 1, aluminum salt and PVP are added into deionized water, and an aluminum salt mixed solution is obtained; (2) adding ammonium salt and cyclic polysaccharide micromolecules into deionized water to obtain an ammonium salt mixed solution; (3) dropwise adding the aluminum salt mixed solution into the ammonium salt mixed solution while stirring, and performing aging, suction filtration, drying and calcination to obtain an alumina carrier; (4) impregnating the alumina carrier with a palladium salt solution; and (5) drying, roasting and reducing the impregnated alumina carrier to obtain the alumina-based catalyst for anthraquinone hydrogenation. Macromolecular PVP (Polyvinyl Pyrrolidone) and cyclic polysaccharide micromolecules are used as composite template agents for ammonium-aluminum coprecipitation, so that not only is an alumina carrier material with a high specific surface area prepared, but also the loading capacity on palladium is improved, the dispersion of palladium is promoted, and the hydrogenation efficiency is favorably improved.

Provided in the present application are a lithium-rich manganese-based precursor material, and a preparation method therefor and the use thereof. The preparation method comprises the following steps: in a protective gas atmosphere, mixing a nickel-cobalt-manganese mixed salt solution, a precipitator solution and a complexing agent solution, subjecting same to a co-precipitation reaction until particles enter a growth stage, starting the introduction of an oxygen-containing gas, and then continuously subjecting same to the co-precipitation reaction, so as to obtain a lithium-rich manganese-based precursor material. In the preparation method of the present application, by introducing the oxidizing atmosphere in the growth stage of the precursor material, the problems of compact particle growth, being prone to agglomerating and poor morphology in the existing preparation process for a lithium-rich manganese precursor material are solved, and a lithium-rich manganese-based precursor material having high dispersity and a high specific surface area is obtained.

The invention provides a silk fibroin hydrogel preparation method, which comprises: S1, dissolving degummed silk in a neutral salt solution to obtain a silk fibroin dissolving solution; s2, diluting the silk fibroin dissolving solution prepared in the step S1 with a diluent to obtain a silk fibroin dissolving diluent; s3, carrying out physical cross-linking treatment on the silk fibroin dissolving diluent prepared in the step S2 or regulating the pH value for physical cross-linking or adding a surfactant for physical cross-linking, and incubating to obtain the silk fibroin hydrogel. The silk fibroin hydrogel is simple in preparation process, high in gelling rate, low in loss and high in raw material utilization rate.

This invention discloses a method for leaching lithium iron phosphate mixed powder with iron salts and recovering all components, belonging to the field of battery recycling. The invention uses an iron salt solution to leach the mixed powder, obtaining a lithium-containing leachate and leaching residue. Ferrous ions in the leachate are regenerated into ferric iron through acidification and oxidation, and recycled for leaching the next batch of mixed powder. After reaching a preset number of cycles, the leachate is used for re-leaching multiple batches of leaching residue to improve the lithium leaching rate. Ultimately, a enriched solution containing Li, Fe, Cu, and Al and graphite-containing iron phosphate residue are obtained. Copper is recovered from the enriched solution through iron powder replacement, and a high-purity lithium chloride solution is obtained through extraction and separation, while ferric chloride (recycled) and aluminum chloride crystals are also recovered. The leaching residue is treated with hydrochloric acid to obtain regenerated graphite, and the pH is adjusted with alkali to obtain high-purity iron phosphate. This method achieves full component recovery under mild conditions, reducing separation steps and chemical consumption through a "leaching-regeneration-leaching" cycle mechanism, thus achieving both environmental and economic benefits.

The invention discloses an electrocatalyst for acidic oxygen evolution reaction as well as a preparation method and application of the electrocatalyst, and belongs to the technical field of electrolyzed water. The preparation method of the electrocatalyst for the acidic oxygen evolution reaction comprises the following steps: growing a transition metal oxide on a conductive substrate in situ to obtain a transition metal oxide carrier; the transition metal oxide carrier is subjected to plasma treatment and then placed in a precious metal salt solution for a cation exchange reaction, and the electrocatalyst is obtained. The electrocatalyst prepared by the invention has extremely low initial overpotential (187mV) when a water electrolysis reaction is carried out in a 0.5 M H2SO4 solution, has no obvious performance degradation in a continuous acidic water electrolysis process for 4500h, shows very high operation stability, and has great application potential in the aspects of replacing a commercial RuO2 / IrO2 catalyst and reducing electrode preparation cost and acidic water electrolysis.

The invention relates to double-layer integrated asymmetric viscous hydrogel as well as a preparation method and application thereof, and belongs to the technical field of hydrogel. The invention relates to a preparation method of double-layer integrated asymmetric viscous hydrogel, which comprises the following steps: adding natural macromolecular polysaccharide and a polymeric monomer into a salt solution, stirring at room temperature, then adding an initiator and a cross-linking agent, stirring and polymerizing to obtain the double-layer integrated asymmetric viscous hydrogel. Through a one-pot method, a salt component is introduced into a hydrogel system, and the hydrogel has a double-layer structure with asymmetric viscosity under the salting-out action; in addition, the hydrogel is doped with a carbon nanotube with the surface modified by polydopamine and silver nanoparticles, so that the mechanical property and the conductivity of the hydrogel are remarkably improved. The preparation method provided by the invention is simple, is suitable for various hydrogel systems, has good universality and is easy to popularize and apply.

A method for preparing modified iron(III) phosphate, comprising the following steps: (1) preparing NH2-MIL-53(Al) nanoparticles, mixing the nanoparticles with a solvent, adding an acid solution, and heating and stirring the mixture to obtain hollow NH2-MIL-53(Al) powder; (2) using the hollow NH2-MIL-53(Al) powder to prepare a dispersion, mixing the dispersion with an iron salt solution, stirring and then drying the mixture, mixing the resulting powder with a phosphorus source solution, controlling the pH, and carrying out a reaction; and (3) carrying out sintering treatment on a material resulting from aging to obtain the modified iron(III) phosphate. Provided are iron(III) phosphate prepared according to the method and a positive electrode material. In the method, a hollow metal organic framework nanomaterial is used as a template to provide a micro reaction area for the synthesis of iron(III) phosphate, so that the microscopic morphology of the prepared iron(III) phosphate is restrained and controlled to prepare nanoscale iron(III) phosphate having a polyhedral structure.

The invention discloses a composite rare earth modified aluminum oxide fluorine removal agent as well as a preparation method and application thereof, and belongs to the technical field of wastewater treatment. The preparation method comprises the following steps: dipping Al2O3 powder into a rare earth nitrate solution, oscillating at constant temperature, filtering, washing, drying, grinding and sieving to obtain the composite rare earth modified aluminum oxide fluorine removal agent; the rare earth nitrate solution contains two or more rare earth nitrates. The rare earth nitrate solution is adopted to modify aluminum oxide, and active sites on the surface of the aluminum oxide are increased due to loading of rare earth metal elements, so that the chemical affinity of the aluminum oxide and fluorine ions is improved, the adsorption capacity of the aluminum oxide fluorine removal agent to the fluorine ions is improved, and the service life of the aluminum oxide fluorine removal agent is prolonged. Finally, the purpose of improving the fluorine removal efficiency and the fluorine removal capacity of the aluminum oxide fluorine removal agent is achieved, and meanwhile toxic and harmful chemical substances cannot be introduced into water.

The invention discloses a method for regulating the length-diameter ratio of calcium sulfate hemihydrate whiskers prepared from ardealite, and belongs to the field of ardealite resource utilization. According to the invention, carbohydrates, alcohols and other substances containing hydroxyl groups are used as the crystal modifier, and the calcium sulfate hemihydrate whisker is prepared by regulating and controlling phosphogypsum through a normal-pressure hydrothermal method, so that the length-diameter ratio of the whisker is regulated and controlled within a certain range. The method solves the problems that the length-diameter ratio of the whisker in the calcium sulfate hemihydrate whisker product prepared from ardealite is not uniform and cannot be regulated and controlled, the preparation process is tedious, the corrosivity is strong due to excessive salt solution in the reaction system, and the waste liquid has great harm to the environment, and has a good application prospect.

The invention provides a method and system for salt separation, evaporation and crystallization of printing and dyeing wastewater, and the method comprises the following steps: sequentially carrying out multi-stage synergistic pretreatment on textile printing and dyeing wastewater to remove suspended solids, degrade organic matters and reduce hardness; the pretreated wastewater is subjected to membrane salt separation treatment, and preliminary separation of salt is achieved through reverse osmosis pre-concentration and nanofiltration salt separation; and respectively carrying out evaporative crystallization treatment on the separated high-concentration salt solution to obtain high-purity sodium sulfate and sodium chloride products. According to the method, the salt recovery rate and the product purity are remarkably improved, the energy consumption and the operation cost are reduced, meanwhile, the problems that in traditional printing and dyeing wastewater treatment, salt is difficult to separate, and the crystallization purity is low are solved, and an innovative solution is provided for high-valued resource recovery of industrial wastewater.

The invention relates to a preparation method of a high-activity transition metal phosphide catalyst, which comprises the following steps: taking basic nickel cobalt carbonate (NiCo-OH / NF) grown on foamed nickel in situ as a precursor, placing the precursor at the downstream of a tubular furnace, placing NaH2PO2 at the upstream of the tubular furnace, annealing in a nitrogen atmosphere at 350 DEG C for 2 hours, and naturally cooling to obtain NiCoP / NF; the preparation method comprises the following steps: soaking NiCoP / NF in a potassium salt solution of a boride, washing, and carrying out vacuum drying to obtain a boron-potassium modified catalyst precursor NiCoP-BK / NF; in a three-electrode system, electrodeposition is carried out in an electrolyte containing a Ni source, a Fe source and deionized water, and the high-activity transition metal phosphide-nickel iron hydroxide NiCoP-BK-coated NiFe-LDH / NF heterojunction composite catalyst is obtained. The activity and stability of the transition metal phosphide catalyst can be remarkably improved, and the preparation method is simple and low in cost.

The invention discloses a low-cost large-molecular-weight fish scale collagen extraction method, and belongs to the technical field of fish scale collagen. The method comprises the following steps: (1) pretreatment: repeatedly freezing and storing fish scales and unfreezing and redissolving the fish scales; 2) impurity protein removal: taking out the fish scales, and removing fish silver; soaking in a sodium chloride solution, washing and drying; 3) extracting fish scale collagen, namely extracting the dried fish scales for 1-4 hours at 40-100 DEG C according to a solid-liquid ratio of 1: (5-20) by adopting a hydrothermal extraction mode, carrying out solid-liquid separation, and collecting fish scale collagen extract liquids in different molecular weight intervals; and 4) freeze-drying the collagen extract liquid to obtain a fish scale collagen solid product. According to the method, acid or alkali solution pretreatment is not needed, and a sodium chloride salt solution is used for mildly removing impure protein. And the structure of the fish scale collagen is relatively completely maintained while the relatively high yield is ensured.

The invention belongs to the technical field of solar cells, and particularly relates to a fluorinated biguanide salt synergistically passivated perovskite solar cell and a preparation method thereof. The method comprises the following steps: S1, coating the surface of a perovskite light absorption layer with a fluorinated biguanide hydrochloride solution to form a synergistic layer; coating the surface of the synergistic layer with a halogenated phenylethylamine solution to form a synergistic passivation layer; and S2, arranging an electron transport layer and a hole blocking layer on the surface of the passivation layer. According to the invention, the synergistic passivation layer is introduced in the preparation process of the perovskite solar cell. The introduction of the fluorinated biguanide salt passivation layer can modify the perovskite crystal and generate the low-dimensional perovskite at the crystal boundary, and the second passivation layer can interact with the low-dimensional perovskite structure, thereby further protecting the perovskite film, improving the interface of the perovskite light absorption layer and the electron transport layer, and improving the short-circuit current density, open-circuit voltage and cell efficiency of the cell.

The invention relates to the technical field of metal amino acid chelate preparation, and discloses high-bioavailability magnesium glycinate and a preparation method thereof.The method comprises the steps that a glycine solution and a magnesium salt solution are mixed, the initial pH value is adjusted to be within the alkaline range, and a low-polarity organic phase is added to construct a two-phase solvent system; dynamically adjusting the pH value of the reaction system by stages, and sequentially inducing amino and carboxyl of glycine to chelate magnesium ions step by step to form a chelate; and blending the chelated product with a chitosan-sodium alginate composite carrier, and carrying out spray drying to obtain magnesium glycinate particles. The molar ratio of magnesium ions to glycine in the chelating structure of magnesium glycinate is 1: 3. Through the synergistic effect of dynamic pH regulation and a two-phase solvent system, directional synthesis of the magnesium glycinate 1: 3 high-coordination chelate is achieved, the bioavailability and the targeted slow release performance are remarkably improved by combining a composite carrier nano embedding technology, and meanwhile, the process is efficient and environmentally friendly.

The preparation method comprises the following steps: S1, preparing a phosphoric acid solution, a hydrogen peroxide solution, a Ti salt, a phosphor salt solution and a ferrite solution; s2, Ti salt and the ferrite solution are mixed, and a titanium iron salt solution is obtained; mixing the phosphoric acid solution and the phosphorus salt solution to obtain a phosphorus source solution; s3, adding the titanium iron salt solution into a reaction kettle, and adding the hydrogen peroxide solution; s4, adding the phosphorus salt solution into the reaction kettle to obtain yellow slurry; s5, after the color of the slurry is heated to be white, white slurry is obtained; s6, carrying out solid-liquid separation on the white slurry to obtain an iron phosphate dihydrate filter cake; and S7, drying and calcining the iron phosphate dihydrate filter cake to obtain the Ti-doped battery-grade anhydrous iron phosphate. The titanium-doped iron phosphate is firstly prepared by a one-step method, the pH value of the reaction system is controlled by controlling the molar ratio of the iron element to all phosphorus elements in total phosphorus, ammonium phosphate and phosphoric acid in the reaction system, and the retention of the Ti element in the finished product and the regulation and control of the iron-phosphorus ratio in a specified range are ensured.

The invention provides an iron manganese phosphate precursor and a preparation method thereof, a lithium iron manganese phosphate positive electrode material and a preparation method thereof, a lithium ion battery and electric equipment, and relates to the technical field of new energy. The ferromanganese phosphate precursor provided by the invention comprises secondary particles composed of a plurality of primary particles, the primary particles are nano dotted particles, the diameter of the primary particles is 20-300nm, the secondary particles are of a blocky structure, and the morphology of the ferromanganese phosphate precursor can improve the electrochemical performance and the compaction density of the material. According to the preparation method of the ferromanganese phosphate precursor provided by the invention, a salt solution is taken as a base solution, and a phosphorus source solution, an oxidizing agent and a pH regulator are jointly fed, so that uniform precipitation of Mn and Fe is realized; regulation and control of nucleation, growth process, crystallinity and dotted primary particle size are realized by regulating and controlling the reaction temperature, the adding rate of the oxidant and the phosphorus source and the reaction pH value.

The invention provides an in-situ synthesis method and application of aluminum-doped battery grade manganous-manganic oxide and lithium manganate. An aluminum-doped manganous-manganic oxide precursor is synthesized in one step through a direct homogeneous oxidation method, and then the lithium manganate positive electrode material is prepared through a high-temperature solid-phase reaction. The technological parameters such as the volume of a base solution, the concentration of a manganese-containing solution, the concentration of ammonia water, the flow of a salt solution, the stirring speed and the reaction temperature are regulated and controlled, and the synthesized manganous-manganic oxide precursor is uniform in particle size and has relatively high tap density and relatively low specific surface area. The capacity retention ratio of the obtained aluminum-doped lithium manganate reaches 85.16% after the aluminum-doped lithium manganate is circulated for 100 circles at the rate of 0.2 C, and the discharge specific capacity of the aluminum-doped lithium manganate is 105.8 mAh / g at the high rate of 5C. According to the method, the efficient recycling of waste battery resources is realized, the production cost is reduced, and meanwhile, the problem of non-uniformity of a conventional doping process is solved.

The invention provides a purification and impurity removal method of a crude nickel-cobalt-manganese sulfate solution. The purification and impurity removal method comprises the following steps: (1) adding sodium thiosulfate into the crude nickel-cobalt-manganese sulfate solution to remove copper; (2) phosphate is adopted, the pH value is regulated, and titanium, iron, aluminum and the like are removed; (3) ferric sulfate is added, the pH value is regulated, and phosphorus and silicon are removed; (4) adding a bismuth agent and regulating the pH value to remove chlorine; (5) adding a fluorine agent to remove calcium and magnesium; and (6) adding a tillite mineral adsorbent to remove fluorine. According to the method, iron, aluminum, copper, fluorine, phosphorus, titanium, calcium, magnesium, chlorine, silicon and other elements can be efficiently removed from the rough nickel-cobalt-manganese sulfate solution, the loss of main metal is low, the prepared high-purity nickel-cobalt-manganese sulfate solution can directly meet the requirement of a precursor solution of a battery preparation level, the process is simple, the operation difficulty is low, industrial large-scale production is easy to achieve, and the method is suitable for industrial production. And the defects of the current preparation method of the high-purity nickel-cobalt-manganese sulfate solution are overcome.

The invention relates to the technical field of electrocatalytic CO2 reduction, and particularly discloses a copper-based electrocatalytic material which comprises a plurality of element-doped copper-based nanowires, and the doped elements are one or more of S, F, Br, N and O. The invention also discloses a preparation method of the copper-based electro-catalytic material, which comprises the following steps: mixing a solution containing the thiophenol ligand with a copper salt solution to obtain a turbid liquid; performing ultrasonic treatment, heating, stirring and aging treatment on the turbid liquid, and then performing centrifugation, washing and drying treatment to obtain a copper-based nanowire precursor; the copper-based nanowire precursor is subjected to roasting; and carrying out in-situ electrochemical activation treatment on the roasted copper-based nanowire precursor. The preparation method is simple and effective, and multi-step doping is not needed. When the copper-based electro-catalytic material is applied to preparation of ethylene through electro-catalytic carbon dioxide reduction reaction, the copper-based electro-catalytic material has high ethylene selectivity and can efficiently and stably work under high current density.

The invention belongs to the technical field of heating bodies, and particularly relates to a method for preparing a sheet-shaped heating body. The preparation method comprises the following steps: stirring and dissolving lanthanum nitrate, strontium nitrate, manganese nitrate hexahydrate and a solvent to obtain a metal salt solution; preparing the metal salt solution into a precursor, wherein the precursor is a precursor solution or precursor sol; and carrying out tape casting and drying on the precursor to obtain a biscuit sheet, and carrying out glue removal treatment and sintering on the biscuit sheet to obtain the sheet-shaped heating body. According to the preparation method, a precursor system is optimized, the dispersion stability of the precursor is improved, casting, drying and sintering processes are matched, the problem of powder agglomeration is solved, the defects of green bodies are reduced, the drying shrinkage rate of green body pieces in the preparation process is reduced, the surface roughness is reduced, the stability and heat output uniformity of a heating body are improved, and the compactness is improved.

The invention relates to the technical field of composite catalyst materials, in particular to a ferrocobalt bimetal hydroxide / BCN composite material and a preparation method and application thereof.The preparation method comprises the steps that cobalt nitrate and ferric nitrate are used for preparing a metal salt solution, sodium carbonate and sodium hydroxide are used for preparing a precipitant solution, a B-doped carbon nitride BCN material is added into the metal salt solution to form a uniform suspension, and the suspension is dried to obtain the ferrocobalt bimetal hydroxide / BCN composite material; dropwise adding the precipitant solution into the suspension to obtain a precursor solution, performing hydrothermal reaction on the precursor solution, and performing centrifugal impurity removal and drying to construct a heterostructure between layered double hydroxide and BCN in situ to obtain the Co-Fe LDH-coated BCN composite material. Through boron doping and heterostructure construction, the charge separation capacity of graphite carbon nitride is enhanced, the electron migration efficiency is improved through a heterointerface structure, the metal ion release amount and the cycle stability are controlled, and the catalytic performance is remarkably improved.

The invention belongs to the technical field of lithium batteries, and particularly relates to a lithium-rich manganese-based positive electrode material and a preparation method and application thereof. The preparation method comprises the following steps: mixing a metal salt solution, a precipitator and a complexing agent, and carrying out coprecipitation reaction on an obtained coprecipitation reaction precursor solution to obtain a lithium-rich manganese-based precursor; the metal salt solution comprises a manganese element, a cobalt element and a nickel element; and mixing the lithium-rich manganese-based precursor, a lithium source, an auxiliary agent and a dispersing agent, and calcining to obtain the lithium-rich manganese-based positive electrode material, the auxiliary agent comprises a nitrogen source or a nitrogen source and a carbon source. The first discharge specific capacity, the rate capability and the cycling stability of the lithium-rich manganese-based positive electrode material can be improved, and the problems of capacity fading, discharge voltage drop and dynamic delay in an electrochemical reaction process are solved.

The invention discloses a method for preparing an iron-nickel-molybdenum-based electrocatalyst through combination of electrodeposition and rapid Joule heat and application of the method. The method comprises the steps that S1, a porous nickel substrate is pretreated, and the pretreated porous nickel substrate is obtained; s2, obtaining a nickel salt solution, a molybdenum salt solution and a ferric salt solution; s3, obtaining a mixed solution; s4, putting the mixed solution serving as electrolyte into a dual-electrode electrolytic tank, carrying out electro-deposition treatment by taking the pretreated porous nickel substrate as a cathode and an inert electrode as an anode, and washing and drying to obtain a Fe-Ni-Mo-LDH precursor; and S5, carrying out Joule thermal pyrolysis treatment on the Fe-Ni-Mo-LDH precursor, so as to obtain the iron-nickel-molybdenum based electrocatalyst. The preparation method can effectively regulate and control the size structure of the catalyst, and is suitable for preparing iron-nickel-molybdenum-based electrocatalysts with different substrates and different sizes; and the electrocatalyst has the advantages of uniform and stable nanostructure and high loading capacity. Meanwhile, the preparation method is short in reaction time, high in heating efficiency, high in repeatability and suitable for industrial large-scale production.

The invention provides a method for preparing sodium carbonate and co-producing ammonium sulfate from sodium sulfate waste salt, and relates to the technical field of chemical engineering. The method comprises the following steps: mixing sodium sulfate waste salt with water for dissolution, mixing the obtained sodium sulfate waste salt solution with an impurity removal agent for impurity removal, and mixing the obtained impurity removal solution with ammonium bicarbonate for double decomposition reaction to obtain a reaction feed liquid; carrying out primary cold separation on the reaction feed liquid to obtain first filtrate and primary sodium bicarbonate; sequentially washing, drying and roasting the primary sodium bicarbonate to obtain a sodium carbonate product; carrying out secondary cold separation on the first filtrate, carrying out solid-liquid separation to obtain a second filtrate and mixed salt, and reusing the mixed salt in the metathesis reaction; and mixing the second filtrate with an acid adjusting agent to adjust the acid, and carrying out evaporative crystallization on the obtained solution to obtain an ammonium sulfate product and an evaporation mother solution. Industrial-grade sodium carbonate and ammonium sulfate are co-produced by using sodium sulfate waste salt, sodium carbonate and ammonium sulfate meet national standard requirements, and the recovery rate of sodium sulfate is greater than or equal to 90%.

The invention belongs to the technical field of chemical catalysis, and particularly relates to a preparation method of an alkali metal cation modified cobalt-nitrogen-carbon monatomic catalyst and application of the catalyst in electrosynthesis of hydrogen peroxide. The Co-N-C / X catalyst is obtained by taking a cobalt-containing compound as a metal source, mixing the metal source with a nitrogen-containing organic matter and a carbon material, performing rotary evaporation, grinding and high-temperature pyrolysis in an inert atmosphere, performing acid washing with strong acid to construct surface defects, and finally performing stirring adsorption with an alkali metal salt solution, suction filtration and drying. Alkali metal cations are physically adsorbed and anchored on the surface and interface of the Co-N-C catalyst instead of being dissolved in a solution, so that the electronic structure of Co active sites and the adsorption energy of the * OOH intermediate are optimized, and the problem of separation of alkali metal and a product is solved. When the catalyst is used for electro-catalytic oxygen reduction reaction, the H2O2 selectivity reaches up to 98%, the preparation process is simple, the cost is low, large-scale production can be realized, and the problems that the traditional method is high in energy consumption and large in pollution and the existing catalyst is insufficient in selectivity are solved.

The invention provides a method for degrading organic phosphorus and recycling phosphorus in water in an ozone oxidation system. According to the method, a mode of adding iron or iron salt solution step by step is innovatively adopted, so that the degradation rate of phosphorus-containing organic matters in water, the generation rate of phosphate radicals and the removal of total phosphorus in water are remarkably improved. Besides, the treatment effect is evaluated by monitoring the organophosphorus mineralization rate (taking the generation amount of phosphate radicals as an index) and the removal rate of total phosphorus in water, experiments show that the method can increase the organophosphorus mineralization rate by 30% or above, and the removal rate of total phosphorus reaches 95%. Compared with the conventional one-time addition of iron or iron salt, the method has the advantages that the mineralization rate of organophosphorus and the removal rate of total phosphorus are effectively improved through a step-by-step addition strategy, the direct precipitation of an organophosphorus intermediate product is promoted, the use amount of ozone and the addition amount of iron are remarkably reduced, the reaction time is greatly shortened, and the recovery efficiency of phosphorus resources is further improved. The method is low in cost and suitable for advanced treatment of organic phosphorus-containing wastewater in the industries of pesticides, electroplating and the like.