667results about "Ferroso-ferric oxides" patented technology

The present invention belongs to the technical field of design and synthesis of carbon-monoxide and carbon-dioxide-based Fischer-Tropsch synthesis catalysts, and discloses a novel iron-based Fischer-Tropsch synthesis catalyst containing both iron and carbon and a synthesis method and use thereof. The present invention specifically relates to a catalyst mixture for use in hydrogenation of CO and / or CO2, which catalyst mixture comprises i) iron oxide promoted by alkali metal, alkaline earth metal or transition metal, and ii) iron carbide. The invention further relates to a method for production of iron carbide composite comprising different iron carbides, and the use of said carbide composite in combination with alkali metal, alkaline earth metal or transition metal promoted iron oxide for use in hydrogenation of CO and / or CO2.

The invention discloses a preparation method and application of a magnetic enrichment composite SERS (Surface Enhanced Raman Scattering) detection chip, gold nanoparticles are electrostatically adsorbed on the surface of a magnetic ferroferric oxide nanoring, the prepared material is subjected to cyclodextrin modification, nanogaps among the gold nanoparticles form hot spots, a local electromagnetic field enhancement effect is generated, and the magnetic enrichment composite SERS detection chip is obtained. The cyclodextrin molecules adsorb PAHs in the environment through a hydrophobic effect and are fixed in an electromagnetic field enhancement area, amplification of Raman signals is achieved, the magnetic material serves as a carrier, aggregation of gold nanoparticles can be effectively prevented, SERS signals can be further enhanced through a magnetic enrichment effect, and therefore, the method has the advantages that the method is simple, and the application prospect is wide. The high-sensitivity and high-selectivity detection of PAHs in the tail gas of the engineering machinery vehicle is realized by constructing the magnetic composite SERS nano sensing chip.

The invention discloses a preparation method and application of a magnetic biochar-loaded bacterium composite functional material, magnetic biochar (MBC) is used as a carrier to load and fix Achromobacter denitrificans BP1 (Achromobacter denitrificans BP1, the NCBI login number is CP154792), and a magnetic biochar-loaded functional bacterium (MBC-coated BP1) is obtained. The invention relates to a water and soil purifying agent which is used for removing pollutants in water and / or soil, the pollutants comprise polycyclic aromatic hydrocarbons (PAHs) and / or heavy metals (HM) and the like, benzo [a] pyrene (BaP) and phenanthrene (Phe) in the soil can be efficiently degraded, Cr (VI) is removed, nitrate (NO3 <->) is metabolized, the soil nutrient level (organic matters, nitrogen, phosphorus and the like) can be increased, the diversity and structural functions of soil microbial communities are improved, and the water and soil purifying agent can be used for purifying water and / or soil. And a green and efficient repairing material and a technical support are provided for a compound pollution complex site.

The invention discloses a heterogeneous nanoflower electrocatalyst and a preparation method thereof. The electrocatalyst is a heterogeneous nanoflower constructed by cross-assembly of ultrathin palladium-based alloy nanosheets and ferroferric oxide nanosheets. The heterogeneous nanoflower contains two physical phases, palladium-based alloy and ferroferric oxide. The palladium-based alloy nanosheets and ferroferric oxide nanosheets cross each other to form a clear interface. The preparation method is simple and feasible, and the process is controllable. The heterogeneous nanoflower electrocatalyst has abundant interface sites, can significantly enhance the electrocatalytic performance, is a new alloy / oxide coupling material system, and is of great significance for improving the electrocatalytic activity and durability.

The invention belongs to the technical field of nuclear magnetic resonance spectrums, and particularly relates to a preparation method of a responsive multi-component material and application of the responsive multi-component material in 129Xe / 1H dual-mode signal change. According to the method, the Fe3O4 (at) SiO2 nanoparticles are used as a precursor, KMnO4 is used as a raw material, the Fe3O4 (at) SiO2 (at) MnO2 nanoparticles are synthesized, and the synthesized nanoparticles are complete in morphology and uniform in size. A transverse relaxation rate 1 / T2 signal of protons of the multi-component material obtained by the strategy is quenched, a dissolved state signal of 129Xe is basically unchanged, but after the reaction with 10mM glutathione, the 1 / T2 signal is recovered, the dissolved state signal of 129Xe is obviously reduced, the change of a 129Xe / 1H double nuclear magnetic resonance signal is realized, and the change of the 129Xe / 1H double nuclear magnetic resonance signal is realized. And the method has certain significance for enriching the application of the hyperpolarized 129Xe magnetic resonance probe and the development of a multi-mode magnetic resonance imaging nano platform.

The invention is suitable for the technical field of OER catalysts, and provides a preparation method of a nanowire array composed of a ferrocobalt-based heterostructure, and the preparation method comprises the following steps: pretreating a foamed nickel substrate; performing in-situ growth of a precursor CoFe-LDH nanosheet on the NF through a hydrothermal method; and synthesizing the nanowire array composed of the ferrocobalt-based heterostructure: putting a precursor into a muffle furnace, heating, keeping the temperature so that the precursor is thoroughly converted into a Co-Fe-O intermediate, immersing NF on which the intermediate grows into a polytetrafluoroethylene reaction kettle lining, carrying out a hydrothermal reaction, and naturally cooling to the room temperature to obtain a Co9S8-Fe3O4 / VNF composite material (the vulcanized NF is abbreviated as VNF), so that the nanowire array composed of the ferrocobalt-based heterostructure and the Co9S8-Fe3O4 / VNF composite material is obtained. The nanowire array is composed of a ferrocobalt-based heterostructure. The invention further provides a nanowire array composed of the ferrocobalt-based heterostructure and application of the nanowire array in preparation of a working electrode of an oxygen evolution reaction catalyst. According to the heterostructure catalyst provided by the invention, the adsorption strength of an OER intermediate can be optimized to realize high intrinsic OER activity, and efficient and stable water decomposition is realized.

The invention belongs to the technical field of wastewater treatment and energy recovery, and provides a regulation and control method for promoting anaerobic acid production by taking soybean molasses as a substrate through cooperation of ferroferric oxide and bamboo charcoal. Soybean molasses is used as a substrate carbon source, anaerobic activated sludge is inoculated in a medium-temperature SBR reactor, the volume ratio of reactor inflow sewage to sludge is 2: 1, ferroferric oxide and bamboo charcoal composite conductive particles which are subjected to ball milling treatment and have the concentration of 1 g / L are added to promote an anaerobic fermentation system to produce acid, and then anaerobic fermentation is carried out. The mass ratio of ferroferric oxide to bamboo charcoal in the ferroferric oxide and bamboo charcoal composite conductive particles is (1: 2)-(2: 1); monitoring the acid yield, the pH value change and the product type; and the variety and concentration of the acid-producing substance are analyzed, and the interaction of all the components in the reaction process is evaluated. The acid production rate and the total acid production amount in the anaerobic acid production process are obviously improved. And the activity of anaerobic flora is promoted. The variety distribution of acid-producing substances is obviously optimized, and the stability of the acidification process is improved.

The invention provides a method for producing carboxyl magnetic beads based on industrial solid waste, and relates to the technical field of carboxyl magnetic bead preparation, and the method comprises the following steps: preparing a saturated solution from ferrous sulfate solid waste; removing heavy metal impurities in the saturated solution by using a mixed extraction agent through an extraction method to obtain a ferrous ion crude product; synthesizing the ferrous ion crude product through a hydrothermal method to obtain ferroferric oxide particles; carrying out hydroxyl coating treatment on the ferroferric oxide particles to obtain hydroxyl coated particles; and carrying out carboxyl coating treatment on the hydroxyl coated particles to obtain the carboxyl magnetic bead material. Ferroferric oxide is produced by taking ferrous sulfate solid waste as a raw material through a hydrothermal method, then separation is carried out through a magnetic field, the separated ferroferric oxide is modified with a silicon hydroxyl coupling agent, the required iron oxyhydroxide magnetic beads are directly obtained, waste resources are utilized in an environment-friendly mode, the production cost is reduced, and the method is suitable for industrial production. And the great potential of improving the product quality and functionality is achieved.

The invention belongs to the field of adsorption materials, and discloses a porous lignin fiber adsorption material and a production process thereof, the porous lignin fiber adsorption material comprises the following raw materials by weight: 40-60 parts of lignin fiber, 20-30 parts of bamboo fiber, 5-15 parts of chitosan, 5-10 parts of sodium bicarbonate, 5-10 parts of attapulgite, 5-10 parts of zeolite, and 2-5 parts of magnetic nanoparticles; the invention aims to provide the production process of the porous lignin fiber adsorption material, the problems that the existing lignin fiber adsorption material is poor in pore structure, limited in adsorption performance, difficult to separate and the like are solved through an innovative raw material formula and an optimized production process, efficient adsorption of light components in asphalt is realized, the stability of an asphalt mixture is enhanced, and the service life of the asphalt mixture is prolonged. Meanwhile, heavy metal ions, organic pollutants and the like are efficiently adsorbed and rapidly separated, the production energy consumption is reduced, and the environmental protection property and economical efficiency of the process are improved.

The invention discloses a preparation method of a wear-resistant magnetic composite nano ferroferric oxide material, and belongs to the technical field of nano ferroferric oxide materials.The preparation method comprises the steps that coated modified ferroferric oxide composite powder, silver nitrate and absolute methanol are added into a reaction kettle, stirring and ultrasonic dispersion are conducted, then 2-aminoterephthalic acid is added, stirring and mixing are conducted, and a mixture is obtained; and after the reaction, separating to obtain the wear-resistant magnetic composite nano ferroferric oxide material. The wear-resistant magnetic composite nano ferroferric oxide material prepared by the preparation method disclosed by the invention overcomes the problem that an existing ferrite material is relatively single in electromagnetic loss mechanism in the aspect of nickel-phosphorus plated fabric, and the electromagnetic shielding effectiveness of the fabric is improved; the coated modified ferroferric oxide composite powder has good dispersity, a polydopamine coating layer on the surface of the coated modified ferroferric oxide composite powder improves the anchoring effect on silver MOF particles through a mussel-like adhesion interface, meanwhile, stress is dispersed and crack propagation is reduced through the buffering effect of the polydopamine coating layer, and the mechanical stability of the wear-resistant magnetic composite nano ferroferric oxide material is improved.

The invention belongs to the technical field of lithium battery material recovery, and particularly relates to a method for recovering a waste lithium iron phosphate positive electrode material. The method comprises the following steps: (1) grinding and sieving the positive electrode material of the waste lithium iron phosphate battery, mixing with an alkaline solution, stirring and leaching, and carrying out solid-liquid separation to obtain a lithium-rich solution and leaching residues; (2) introducing a saturated sodium carbonate solution into the obtained lithium-rich solution, carrying out heating reaction, filtering, taking a solid phase, and drying to obtain lithium carbonate; and the obtained leaching residues are dried, and ferroferric oxide is obtained. According to the method, the waste lithium iron phosphate battery positive electrode material is leached through the alkaline liquid phase, it can be guaranteed that lithium and iron in waste lithium iron phosphate are separated through a one-step leaching method, and therefore selective lithium extraction is achieved. The whole technological process is convenient to operate, mild in reaction condition and low in energy consumption, does not need to use any acid or oxidant, avoids generation of a large amount of waste liquid and harmful gas, and is high in selective lithium extraction efficiency.

The application relates to a method for one-step synthesis of strong magnetic hydrophobic Fe3O4 nanoparticles at low temperature and the Fe3O4 nanoparticles and application, and belongs to the technical field of nano material preparation. The method comprises the following steps: adding a ferrous sulfate solution into a mixed solution of sodium hydroxide and sodium nitrate, heating and stirring to react, adding oleic acid in the reaction process, and obtaining black Fe3O4 crystals after the reaction is completed. The saturation magnetization of the obtained strong magnetic hydrophobic Fe3O4 nanoparticles can reach 85.69 emu / g at most, and the water contact angle can reach 148.95 DEG. The one-step synthesis reaction only needs to use oleic acid as a regulator, avoids an extreme high-temperature and high-pressure environment, does not need to use a toxic chemical solvent, the condition is mild, the process is simple, the operation condition is easy to control, and the method has a wide application prospect.

The invention relates to the technical field of high-performance composite materials, and provides a frequency band magnetic control adjustable one-dimensional nanotube composite wave-absorbing material and a preparation method thereof.The material is composed of a one-dimensional tubular ferroferric oxide matrix and manganous-manganic oxide wrapping the outer side of the matrix, and directional arrangement is conducted through magnetic control rotation. The preparation method comprises the following steps: preparing an iron oxyhydroxide precursor through a hydrothermal synthesis method; the preparation method comprises the following steps: reducing an iron oxyhydroxide precursor by a liquid-phase pyrolysis method, and coating a manganous-manganic oxide shell layer in situ at the same time, so as to obtain a nanotube ferroferric oxide / manganous-manganic oxide composite material; and carrying out orientation arrangement on the nanotube-shaped ferroferric oxide / manganous-manganic oxide composite material through magnetic field control. According to the preparation method and the structural design, the yield, the uniformity, the magnetic performance, the electromagnetic wave absorption efficiency, the multi-band electromagnetic loss enhancement and the like of the material are remarkably improved.

According to the method, sodium carbonate, limestone and coke are used as sintering aids and are uniformly mixed with the high-iron Bayer process red mud, the mixed material is sintered by adopting a one-step low-calcium reduction sintering process, and the sintered clinker is subjected to water leaching and dissolution to obtain a sodium aluminate crude solution and filter residues. And returning the sodium aluminate crude liquid to an aluminum oxide industrial production line to prepare aluminum oxide, and carrying out a hydrolysis alkali recovery process on filter residues to obtain industrial sodium carbonate. The hydrolysis residues are subjected to magnetic separation and recovery to obtain fine iron powder, and the remaining tailings are completely harmless and can be used as raw materials of building materials or used for soil backfilling. The process is characterized in that the one-step low-calcium reduction sintering temperature is 200-300 DEG C lower than the sintering temperature of a sintering method, and the energy consumption is low; na2CaSiO4 is a sintering target product, Ca2SiO4 generally generated by a traditional sintering method is not generated, the situation that Ca2SiO4 is hydrolyzed in the water leaching process to inhibit dissolution of aluminum oxide is avoided, and the recycling rate of aluminum oxide is increased while the using amount of limestone is greatly reduced. The technological process is simple, efficient, energy-saving and free of three-waste emission, and the method is a novel method capable of treating the high-iron red mud in a large-scale and reduction mode.

The invention relates to a method for preparing an efficient electromagnetic shielding graphene film by using a rapid Joule heat technology, and belongs to the technical field of functional materials and application thereof. The method comprises the following steps: firstly, preparing a graphene oxide film through vacuum filtration, then carrying out pre-reduction treatment under the protection of argon, heating the film to 700 DEG C, and carrying out heat preservation for 1 hour so as to remove part of oxygen functional groups; and then, soaking the pre-reduced film in a ferric chloride ethanol solution, introducing a Fe3O4 nanoparticle precursor, and carrying out discharge treatment for 0.1 second under the voltage of 100V through a rapid Joule thermal reduction technology to realize rapid reduction of graphene oxide and doping of Fe3O4 nanoparticles. The finally prepared graphene film shows excellent electromagnetic shielding effectiveness in an X wave band (8-12 GHz), the electromagnetic shielding effectiveness reaches 38 dB, and the electromagnetic shielding effectiveness is improved by 2 dB compared with a sample (36 dB) not doped with Fe3O4. The method has the advantages of being easy and convenient to operate, low in energy consumption and high in reduction efficiency, meanwhile, the synergistic effect of conductivity loss, magnetic loss and dielectric loss is achieved through introduction of the Fe3O4 nanoparticles, the electromagnetic shielding performance of the material is remarkably improved, and the method is suitable for the fields of electromagnetic interference protection of electronic equipment and the like.

The present invention discloses a silicon-carbon negative electrode material modified with a magnetic transition metal oxide and a preparation method thereof, and belongs to the technical field of lithium-ion battery micro-nano materials. The preparation method provided by the present invention has readily available raw materials, low prices, a simple preparation process flow, easy operation, low energy consumption, and environmental friendliness in the preparation process. The prepared silicon-carbon negative electrode material has a uniform and dense modified layer containing a magnetic transition metal oxide, which can effectively improve the conductivity, high specific capacity, and cycle stability of the silicon-carbon negative electrode material. The first coulomb efficiency reaches more than 80%, and the specific capacity can be stabilized to a maximum of 1127mAh / g after 100 cycles, which is much higher than the current average level of this type of material. In addition, the prepared silicon-carbon negative electrode material has excellent mechanical flexibility and can be directly used in the assembly of lithium-ion batteries, and has strong application potential in flexible wearable electronic devices in the future.

The present invention relates to a method for the refining of a material comprising iron oxide and at least one contaminant selected from the group consisting of halogen and sulfur by reducing the content of the at least one contaminant, characterized by calcining the material in the presence of a gas containing water vapor. The invention also relates to a refined material obtainable from such a method and the use for catalyst production.

The invention discloses a method for obtaining a high-performance supercapacitor negative electrode material by introducing dislocation and oxygen vacancy, and belongs to the technical field of supercapacitor and battery electrode materials. A hydrazine hydrate reduction method under the assistance of a magnetic field is adopted, Ni3Fe nanospheres generated by a magnetic field induction reaction are linearly arranged into a nano chain along the magnetic field, and an anoxic environment is created on a reaction interface by regulating and controlling the proportion and temperature of argon and oxygen, so that the final reaction product Fe3O4 realizes introduction of oxygen vacancies due to insufficient oxygen in the reduction process; through temperature control, the rapid reduction process of hydrazine hydrate is realized, atoms are difficult to arrange into a perfect crystal structure, and due to the fact that the Fe reduction process is accompanied with the Fe3O4 conversion process, more structural disorder exists in Fe3O4, a large amount of blade dislocation is introduced, and finally the supercapacitor negative electrode material rich in dislocation Ni3Fe and Fe3O4 is synthesized. The electrochemical performance of the electrode material is improved on the premise that electrode components are not changed.

The invention relates to the technical field of recycling of waste battery materials, and discloses a recycling method of lithium iron phosphate battery waste, which comprises the following steps: carrying out sufficient acid leaching on the lithium iron phosphate battery waste, and carrying out solid-liquid separation to obtain a leachate; adding a sufficient amount of iron ion complexing agent competing with phosphate radicals and a sufficient amount of lithium precipitation inhibitor competing with lithium ions into the leachate, and diluting to obtain a mixed solution; the temperature is controlled to be 20-50 DEG C, alkali liquor is gradually added into the mixed solution, when the pH value of the solution reaches 3.5-4.5, the alkali liquor continues to be added, oxygen is introduced into the solution at the same time, when ferrous iron in the solution is oxidized to 30-40%, oxygen introduction is stopped, the condition is maintained for 8-12 min, after it is detected that a ferroferric oxide product appears in a system, the pH value of the solution is rapidly adjusted to 7.5-8.5, and the ferroferric oxide product is obtained. Fully aging to obtain slurry containing ferroferric oxide; and ferroferric oxide is extracted from the slurry. According to the method, ferroferric oxide with relatively high purity can be recovered and obtained.

The invention belongs to the technical field of nucleic acid extraction and magnetic bead preparation, and relates to a preparation method, an extraction reagent and an extraction method of a magnetic bead for total nucleic acid extraction of a trace cell sample. The preparation method comprises the following steps: 1, preparing magnetic fluid Fe4O3; 2, carrying out silicon-based coating on the surface of the prepared magnetic fluid Fe4O3; and 3, carrying out carboxyl modification on the surface of the magnetic bead obtained through silicon-based modification to obtain the magnetic bead for nucleic acid extraction, namely the carboxyl magnetic bead. The carboxyl magnetic beads obtained by the process provided by the invention are more favorable for obtaining high-concentration nucleic acid under the condition of low sample size, and can meet the requirements of third-generation sequencing or single-cell sequencing.

The invention belongs to the technical field of SERS (Surface Enhanced Raman Scattering) detection, and relates to a preparation method of an Ag-Fe3O4 composite SERS substrate and application of the Ag-Fe3O4 composite SERS substrate in monitoring trace pollutants in water. Based on a plasma-semiconductor synergistic enhancement mechanism, cubic Fe3O4 nano particles with exposed {100} crystal faces are synthesized through a hydrothermal method, and the cubic Fe3O4 nano particles and Ag nano particles are subjected to ultrasonic-stirring to construct the Schottky heterojunction. The substrate creatively realizes dual-channel enhancement: the local surface plasmon resonance effect of Ag nanoparticles generates electromagnetic enhancement, the narrow band gap of Fe3O4 promotes photo-induced electrons to be transferred to Ag, an interface electric field is formed, and the polarizability of adsorption molecules is remarkably increased. When the probe is applied to detection of trace pollutants in a water body, the probe molecule RB is anchored on the surface of Fe3O4 through carboxyl, and the HOMO energy level of the probe molecule RB and the valence band top of Fe3O4 generate resonance charge transfer, so that the Raman cross section is improved. The detection limit of RB under 0.25 mW laser is increased by several orders of magnitude compared with that of a single Ag substrate.

The invention provides a preparation process and application of rock sugar syrup, and belongs to the technical field of food production and processing. The purified high fructose corn syrup, purified mogroside and other high-purity components are used, the impurity content in the rock candy syrup raw materials is reduced, modified activated carbon is matched for adsorption treatment, the ash content of the rock candy syrup is reduced through the comprehensive effect, and meanwhile the light transmittance of the syrup is improved.

The invention discloses lithium sulfide and a preparation method thereof. The preparation method comprises the following steps: (1) carrying out ball-milling mixing on iron powder, sodium sulfide and lithium sulfate in a first inert atmosphere to obtain a mixture; (2) calcining the mixture in a second inert atmosphere for the first time to obtain a reaction material; (3) stirring and washing the reaction material with an alcohol solvent in a third inert atmosphere, filtering to obtain filtrate and a filter cake, performing reduced pressure distillation on the filtrate to obtain a lithium sulfide crude product, washing the filter cake with deionized water, and filtering to obtain a solid by-product; and (4) carrying out secondary calcination on the lithium sulfide crude product in a fourth inert atmosphere to obtain lithium sulfide. The preparation method provided by the invention has the advantages of few synthesis steps, simple product purification and environmental protection.

The invention discloses a resource recycling method of waste lithium iron phosphate batteries, which comprises the following steps: mixing lithium iron phosphate black powder and a chlorinating agent, and performing chlorination separation roasting to obtain roasted sand and flue gas; and the roasted product is subjected to leaching treatment, and flue gas is subjected to defluorination and dechlorination treatment through a semi-dry method. According to the recycling method, the chlorinating agent is introduced for chlorination separation roasting, phosphorus in lithium iron phosphate reacts with the chlorinating agent to generate a phosphorus-containing compound phase, high-temperature reduction conversion of iron is achieved through graphene / carbon black in the black powder, and a magnetite phase is formed; a phosphorus-containing compound phase and a magnetite phase generated in the chlorination segregation roasting process are subjected to high-temperature segregation, and lithium exists in the form of a lithium-containing compound. And the roasted sand and the flue gas are treated at the same time, so that various recycled products can be obtained, the emission of the flue gas is reduced, and the high-value recycling purpose is achieved.

The invention belongs to the technical field of solid waste treatment and resource recovery, and particularly relates to a method for efficiently recovering iron ore concentrate from iron-containing waste. The method comprises the following treatment steps: (1) uniformly mixing the iron-containing waste with a concentrated alkali solution and an additive; (2) carrying out a hydrothermal reaction on the mixture, and after the hydrothermal reaction is finished, carrying out solid-liquid separation to obtain an iron-enriched phase and a concentrated alkali solution; and (3) washing the iron-enriched phase with hot water to obtain an iron-enriched phase and washing liquid, and carrying out magnetic separation on the iron-enriched phase to obtain iron ore concentrate and tailings. The method is short in technical process, iron resources can be efficiently recycled in the form of iron ore concentrate after one-step reaction, a high-temperature calcination environment of a pyrometallurgy means is not needed, the process energy consumption is low, the requirement for a device is low, and the treatment cost is low. The used concentrated alkali solution can be recycled, the washing liquid can also be returned to the concentrated alkali solution for repeated use, the consumption of chemical reagents is low, and wastewater and waste gas are nearly zero in emission.

The invention discloses terahertz wave-absorbing foam based on magnetically-induced gradient distribution carbon nanotubes and a preparation method, and belongs to the technical field of photoelectric materials and devices. The terahertz wave-absorbing foam comprises a porous framework and a wave-absorbing agent distributed in the porous framework, wherein the porous skeleton is a PDMS matrix with holes, the wave-absorbing agent is MWCNT modified by Fe3O4 nanoparticles, and the mass percentage of the wave-absorbing agent in the wave-absorbing foam is 3-7wt%. The dielectric constant of the wave-absorbing foam is regulated and controlled by controlling the concentration of the MWCNT modified by the Fe3O4 nanoparticles, and the concentration of the MWCNT can be guided to be distributed in a longitudinal gradient manner by using an external magnetic field, so that surface electromagnetic impedance matching is realized, and finally reflection suppression and absorption enhancement of electromagnetic waves are completed; meanwhile, large-area preparation can be realized by using white granulated sugar as a sacrificial template, and the method is suitable for industrial production.

The invention provides double-signal sensing gel skin as well as a preparation method and application thereof, and relates to the technical field of flexible sensing. The preparation method of the double-signal sensing gel skin comprises the following steps: dispersing superparamagnetic ferroferric oxide colloidal nanoparticles in a hydrogel precursor solution to obtain a gel solution, and curing the gel solution in a magnetic field to obtain the gel skin, uniformly mixing water and glycerol, and adding anhydrous lithium chloride powder for multiple times under an ultrasonic condition to obtain a displacement liquid; completely immersing the gel skin into the replacement liquid to obtain the double-signal sensing gel skin. Superparamagnetic ferroferric oxide colloidal nanoparticles are used as a photonic crystal color-changing material to realize optical sensing, a glycerol / water binary solvent is used as an environment-resistant solvent to improve the low-temperature environment tolerance of gel skin, and anhydrous lithium chloride is used as a high-conductivity unit and a self-regeneration material to realize self-regeneration of the gel skin. Anhydrous lithium chloride and glycerol generate a synergistic effect of reducing the freezing point, and almost no ice crystal is formed within the temperature change of 20-40 DEG C.

The invention relates to a method for preparing fine iron powder by removing impurities from hematite slag in hydrometallurgy, and belongs to the technical field of chemical metallurgy. The method comprises the following steps: carrying out acid dissolution, impurity removal, washing and filtration on hematite slag produced in a hydrometallurgy process, mixing the hematite slag with a carbonaceous reducing agent, heating the mixed product to 800-1350 DEG C by adopting gas combustion, carrying out heat preservation reaction for 1-4 hours, and after the reaction is finished, carrying out rapid cooling, fine grinding and magnetic separation to obtain the high-purity hematite slag. The iron fine powder contains more than or equal to 70% of iron, less than or equal to 0.5% of zinc, less than or equal to 3.0% of sulfur, less than or equal to 0.1% of copper, less than or equal to 0.1% of lead, less than or equal to 0.1% of arsenic, less than or equal to 0.05% of phosphorus and less than or equal to 1.5% of SiO2. The method has the advantages that the residual impurities of the hematite slag can be deeply removed, the high-quality fine iron powder is obtained, the resource utilization rate of the hematite slag is high, the impurity removal efficiency is good, and the quality of the fine iron powder is good.

The invention relates to a preparation process of a lithium ion composite battery negative electrode material with low impedance and high rate performance. The preparation method comprises the following steps: pretreatment of artificial graphite, preparation of hollow ferroferric oxide nanospheres (H-Fe3O4), preparation of disordered nitrogen-doped carbon-coated hollow ferroferric oxide nanospheres (H-Fe3O4 (at) NC), preparation of carbon-coated artificial graphite (Ag (at) C), preparation of a porous graphite composite material (PG (at) C (at) SEI for rapid charging, preparation of an artificial SEI high-conductivity porous graphite negative electrode material (PG (at) C (at) SEI), and construction of the composite negative electrode material (rGO (at) PG (at) C (at) SEI (at) H-Fe3O4 (at) NC). According to the preparation method, a high-temperature treatment method, a doping combination method, a carbonization combination method and an etching method are creatively combined, the prepared battery negative electrode material shows good impedance high-rate performance, and the charging and discharging efficiency and the cycling stability of a lithium ion battery can be effectively improved.