CN109332681A - Carbon-coated iron-tri-ferrous carbide magnetic nanoparticle preparation method - Google Patents

Carbon-coated iron-tri-ferrous carbide magnetic nanoparticle preparation method Download PDF

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CN109332681A
CN109332681A CN201811486242.0A CN201811486242A CN109332681A CN 109332681 A CN109332681 A CN 109332681A CN 201811486242 A CN201811486242 A CN 201811486242A CN 109332681 A CN109332681 A CN 109332681A
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iron
carbon
tri
magnetic nanoparticle
potassium bromide
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CN109332681B (en
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李海鹏
赵利新
戴西斌
孙雪宇
李超杰
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Hebei University of Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/16—Metallic particles coated with a non-metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • B22F9/26—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions using gaseous reductors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/26—Deposition of carbon only

Abstract

The preparation method of the carbon-coated iron-tri-ferrous carbide magnetic nanoparticle of the present invention, it is related to wrapping iron-containing catalyst, this method is by the mixed solution of ironic citrate and potassium bromide, the ironic citrate particle as ferrous metal source for being evenly distributed on potassium bromide carrier surface is obtained by Freeze Drying Technique, iron oxide-potassium bromide catalyst presoma is obtained using calcining, then use chemical vapour deposition technique that magnetic nanoparticle outer layer is made as carbon-coating, core is carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product that iron and tri-ferrous carbide constitute core, the purity for overcoming obtained carbon-encapsulated iron nano particle existing in the prior art is low, the dispersibility of particle and the poor controllability of partial size, the crystallization degree of particle is low, the defect that stability is poor and comprehensive performance is bad.

Description

Carbon-coated iron-tri-ferrous carbide magnetic nanoparticle preparation method
Technical field
Technical solution of the present invention is related to wrapping iron-containing catalyst, and specifically carbon-coated iron-tri-ferrous carbide is magnetic The preparation method of nano particle.
Background technique
Carbon-coated magnetic nano particle (Carbon-encapsulated magnetic nanoparticles, referred to as CEMNPs) there is good chemical property, optical property, magnetic property, absorption property and good biocompatibility, There are huge application prospects for electricity, magnetic, photocatalysis and field of biomedicine.It is thus in recent years, this novel nano combined Material causes the extensive interest of scientific research personnel and expands a series of research work.The type of carbon-coated magnetic nano particle It is numerous, wherein carbon-coated iron-tri-ferrous carbide magnetic nanoparticle be by nano iron particles by carbon solution modeling effect after Obtained iron-tri-ferrous carbide nanometer core and closely around core carbon-coating form.This unique core-shell structure makes it have Apparent performance advantage.Firstly, since the protective effect of inertia carbon shell, avoids environment to the shadow of core ferromagnetic nano material It rings, such as the oxidation of core ferromagnetic nano material, so that solving iron-tri-ferrous carbide nano particle cannot stablize in air There are the problem of；Secondly, Armco magnetic iron-tri-ferrous carbide nano particle is coated among carbon-coating, magnetic Nano can be effectively reduced Powerful Van der Waals force between particle, reduces influencing each other for the magnet unit closed on, to make at the phenomenon that reducing reunion Magnetic property is obtained to be increased dramatically；Again, carbon-coated iron-tri-ferrous carbide magnetic nanoparticle has had both carbon material high-ratio surface Product, high temperature resistant and corrosion resistant characteristic and iron-tri-ferrous carbide nano particle magnetic property and catalytic performance.Therefore, this novel Carbon-coated magnetic nano particle realize the multifunctionality and separability of material, have in many fields very high using valence Value, specifically include catalyst, magnetic recording, Magnetic Isolation, biomedicine, targeted drug transport, electro-magnetic wave absorption, magnetic resonance at Picture and nuclear waste disposal field.But preparing iron-tri-ferrous carbide magnetic nanoparticle in the prior art, there are still made Carbon-coated iron-tri-ferrous carbide magnetic nanoparticle the structure obtained is bad, it is difficult to guarantee that its performance is stablized；Purity is low, limitation Its performance and application；Synthesize low output, it is difficult to the defect of batch production.Therefore, it is still necessary to further innovate carbon-coated iron- The synthesis technology of tri-ferrous carbide magnetic nanoparticle improves its purity and performance, solves to face in its preparation and application process Problems.
In terms of the preparation of carbon-coated iron-tri-ferrous carbide nano particle, main process has carbothermic method, heat Solution, hydro-thermal method, pulsed laser deposition, arc discharge method etc..For example, to report a kind of carbon-encapsulated iron nanometer multiple by CN107127335A The preparation method of condensation material is by the addition of short nickel stick dissolved with the toluene of ferrocene, dimethylbenzene or hexamethylene organic solution, and in nitrogen Microwave heating is carried out under gas shielded, so that carbon-encapsulated iron nanocomposite be made；CN106732598A discloses a kind of carbon packet The preparation method for covering iron nanocatalyst is the mixed solution that sucrose and hydrazine hydrate are added dropwise to iron nitrate solution, is utilized Presoma obtained is carbonized in a nitrogen atmosphere after drying, and annealing obtains carbon-encapsulated iron nanocatalyst；CN104785777A is public The preparation method of the compound of carbon nanotube/graphite coat iron nano-particle has been opened, Co (Fe, Ni) has been deposited on the monosilicon and closes After carbon nanotube, using carbon nanotube and ferrocene as carrier and source metal, plasma enhanced chemical gas is used The compound of phase sedimentation preparation carbon nanotube/graphite coat iron nano-particle；CN102990075A reports a kind of prepare The method of Carbon-coated iron nanoparticles prepares nanometer Fe using ferrous sulfate and sodium hydroxidexOyHydrate, then pass through liquid alkane Organic carbon-coated Fe is made in refluxxOyCarbon-coated iron nanoparticles are made finally by being heat-treated in particle；CN102784913A report The road hydrothermal preparing process of carbon-encapsulated iron nano particle is will to collect after glucose and nitric acid iron mixed solution hydro-thermal reaction To powder calcined under inertia/reducing atmosphere and obtain carbon-encapsulated iron nano particle；CN1935415A reports a kind of charcoal bag The magnetic superfine iron particle and its manufacturing method covered, using ball milling mixing nano ferriferrous oxide and interleaving agent, later hydrogen, The magnetic superfine iron particle of chemical vapor deposition method for preparing carbon/carbon cladding is utilized under the mixed atmosphere of carbon-source gas and inert gas； CN104117339A reports the preparation method of the adsorbent for adsorbing dyestuff, is first to be prepared with ferric trichloride and sodium hydroxide Carbon-encapsulated ferromagnetic nano is made according still further to certain proportion addition glucose utilization hydro-thermal method in the iron catalyst of sodium chloride load Grain adsorbent；CN101710512A reports the preparation method of graphene Yu carbon-encapsulated ferromagnetic nano metal composite material, is After precipitating reagent to be added to the mixed solution of ferromagnetic metal salt and graphene oxide, the composite granule being collected into is in hydrogen and carbon source Chemical vapor deposition is carried out under gas, obtains graphene/carbon encapsulated ferromagnetic nano metal composite material.The above-mentioned prior art is general Store-through is in following defect: obtained carbon-encapsulated iron nano particle purity is low, reunites serious, the poor controllability of partial size, particle Crystallization degree is low, stability is poor, comprehensive performance is bad, urges to limit carbon-encapsulated iron nano particle in electricity, magnetics, light The extensive use in the fields such as change and biomedicine.
Summary of the invention
The technical problems to be solved by the present invention are: providing the preparation of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle The mixed solution of ironic citrate and potassium bromide is evenly distributed on bromination potassium carrier table by Freeze Drying Technique acquisition by method The ironic citrate particle as ferrous metal source in face obtains iron oxide-potassium bromide catalyst presoma using calcining, then adopts It is carbon-coating that magnetic nanoparticle outer layer, which is made, with chemical vapour deposition technique, and core is the carbon coating that iron and tri-ferrous carbide constitute core Iron-tri-ferrous carbide magnetic nanoparticle product, overcome obtained carbon-encapsulated iron nano particle existing in the prior art Purity is low, the poor controllability of dispersibility of particle and partial size, the crystallization degree of particle is low, stability is poor and comprehensive performance not Good defect.
The present invention solves technical solution used by the technical problem: carbon-coated iron-tri-ferrous carbide magnetic Nano The mixed solution of ironic citrate and potassium bromide is evenly distributed on bromination by Freeze Drying Technique acquisition by the preparation method of grain The ironic citrate particle as ferrous metal source on potassium carrier surface obtains iron oxide-potassium bromide catalyst forerunner using calcining Then body uses chemical vapour deposition technique that magnetic nanoparticle outer layer is made as carbon-coating, core is that iron and tri-ferrous carbide constitute core The carbon-coated iron of the heart-tri-ferrous carbide magnetic nanoparticle product, the specific steps are as follows:
The first step prepares iron oxide-potassium bromide catalyst presoma:
It is with mass percent concentration by the five citric acid monohydrate water solutions that mass percent concentration is 1~3% first 10.03~16.7% kbr aqueous solution is mixed to form mixed solution, it is ensured that wherein iron and the mass ratio of potassium bromide are 0.01 ~0.05: 1, above-mentioned mixed solution is added in 50~70 DEG C of revolving speeds with 300~500rpm using magnetic heating stirrer 2~4h of thermal agitation is then transferred to plastic test tube and is placed in freeze drying box, is cooled down with the cooling rate of 5~20 DEG C/min To -10~-50 DEG C, above-mentioned mixed solution continues in freeze drying box under the vacuum of 1.3~13.0Pa after being frozen into solid-state Dry 24~48h, then from taken out in plastic test tube it is freeze-dried after obtain be evenly distributed on potassium bromide carrier surface As the ironic citrate particle in ferrous metal source, 10~30min is ground at 600~800rpm using planetary ball mill, by ball The ironic citrate particle as ferrous metal source for being evenly distributed on potassium bromide carrier surface obtained after mill is put into Ovenized electricity It hinders in furnace, in air atmosphere 400~700 DEG C of 30~90min of calcining, iron oxide-potassium bromide catalysis is made after being cooled to room temperature Agent presoma；
Second step prepares carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product:
Use chemical vapour deposition technique that magnetic nanoparticle outer layer is made as carbon-coating, core is that iron and tri-ferrous carbide constitute core The carbon-coated iron of the heart-tri-ferrous carbide magnetic nanoparticle product, the specific process is as follows:
Iron oxide-potassium bromide catalyst presoma of above-mentioned first step preparation is taken to be laid in quartzy Noah's ark, by square quartz Boat is placed in the flat-temperature zone of horizontal pipe furnace and closes tube furnace, and extracting the air in tube furnace by mechanical pump makes in tube furnace Vacuum degree reaches -0.05~-0.1MPa, is then slowly introducing argon gas into tube furnace with the flow velocity of 5~30mL/min, works as tubular type After vacuum degree is zero in furnace, adjustment argon flow is 100~300mL/min and with the heating rate of 2~10 DEG C/min by tubular type Furnace is warming up to 600~900 DEG C of reduction temperature of iron oxide, after reaching the reduction temperature, closes argon gas and is passed through flow at once and is The hydrogen of 100~200mL/min, and keep 0.5~2h that iron oxide is reduced to iron catalyst particle, furnace temperature is then adjusted to carbon The iron of cladding -300~450 DEG C of tri-ferrous carbide magnetic nanoparticle growth temperature, close hydrogen and be passed through at once flow for 10~ The acetylene gas of 30mL/min and the argon gas of certain flow, it is ensured that acetylene gas in the mixed gas of above-mentioned acetylene gas and argon gas Flow-rate ratio with argon gas is 1:5~15, and 10~60min of heat preservation carries out the life of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle It is long, it finally closes acetylene gas and adjusts the flow of argon gas to 100~200mL/min, stopping diamond heating making reaction product It is cooled to room temperature under argon atmosphere protection, the carbon-coated iron-carbonization for being evenly distributed on potassium bromide carrier surface is thus made Three ferromagnetic nanoparticles；
By the carbon-coated iron-tri-ferrous carbide magnetic nanoparticle obtained above for being evenly distributed on potassium bromide carrier surface It is added to the suspension for forming that concentration is 1~3mg/mL in distilled water, using ultrasonic disperse instrument with the frequency of 20~50kHz to upper It states suspension and carries out 20~40min of ultrasonic cleaning, above-mentioned suspension is transferred in centrifuge tube and in supercentrifuge later On 10~20min is centrifugated with the revolving speed of 8000~10000rpm, with will after the supernatant in rubber head dropper removal centrifuge tube Centrifuge tube is placed in electric drying oven with forced convection in 50~70 DEG C of 6~8h of drying, and it is carbon-coating that magnetic nanoparticle outer layer, which is thus made, Core is carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product that iron and tri-ferrous carbide constitute core, and purity reaches 97 ~99.5%, saturation magnetization reaches 30.53~94.8Oemu/g, and coercivity reaches 458.83~821.33Oe.
The preparation method of above-mentioned carbon-coated iron-tri-ferrous carbide magnetic nanoparticle, related raw material pass through quotient Purchase obtains, and equipment used and technique are that those skilled in the art will appreciate that.
The beneficial effects of the present invention are: compared with prior art, substantive distinguishing features outstanding that the present invention has and significant Progress is as follows:
(1) compared with a kind of preparation method of hud typed carbon-encapsulated iron nanocomposite of CN107127335A, the present invention The substantive distinguishing features outstanding having and marked improvement are:
Carbon-encapsulated iron or iron-base magnetic nano particle are remembered in adsorbent material, the magnetic of pharmaceutical carrier, heavy metal or organic dyestuff The fields such as material are recorded in use, all proposing strict requirements to the dispersibility of the partial size of the material and particle. CN107127335A prepares carbon-encapsulated iron nanocomposite using microwave metal discharge method, and ferrocene is dissolved in toluene, diformazan Benzene or hexamethylene organic solvent, ultrasound mix and the short nickel stick of discharge medium are added, and are put into industrial microwave oven later, protect in argon gas Lower carry out microwave heating.After reaction, it screens out discharge medium and grinds uniformly, obtain carbon-encapsulated iron nanocomposite.It should The prior art is due to the semi liquid state environment that reaction environment is in liquid or organic solvent carbonisation, at high operating temperatures, two cyclopentadienyls It can increase in the iron catalyst that iron decomposites, and warm-up movement occur in liquid solvent, due to van der Waals interaction, necessarily lead Causing a large amount of iron catalyst nanoparticles to reunite and be bonded together causes partial size to increase.According to existing result of study, catalyst Particle size seriously affect its catalytic performance: catalyst particle size increases, and catalytic performance significantly reduces.Therefore, the iron of reunion Nano particle catalytic performance seriously reduces, and leads to that the carbon-encapsulated iron nanocomposite partial size of synthesis is big, bad dispersibility, partial size It is unevenly distributed and performance is poor.
The present invention in the design process, has fully considered how to improve carbon-coated iron-tri-ferrous carbide magnetic nanoparticle Dispersibility and uniformity, it is prepared carbon-coated in existing invention in order to solve and then the problem of improve its service performance Iron-tri-ferrous carbide magnetic nanoparticle bad dispersibility, particle diameter distribution unevenly lead to the problem of service performance difference, and innovative mentions Go out and ironic citrate is loaded to by potassium bromide surface by the method for freeze-drying, acquisition is evenly distributed on potassium bromide carrier surface The ironic citrate particle as ferrous metal source, be in detail, by uniformly mixed potassium bromide and citric acid solution cold Dry composite under jelly state obtains the work for being dispersed in potassium bromide carrier surface by subsequent ball milling, calcining, reducing process For the ironic citrate particle in ferrous metal source, which is iron catalyst particle, also, by adjusting potassium bromide and Concentration proportioning and subsequent ball milling, calcining, the reducing process of citric acid solution realize accurate adjust to the partial size of iron catalyst particle Control.In addition, its catalytic performance is given full play in order to avoid the reunion of iron catalyst particle, using the method for chemical vapor deposition Catalytic pyrolysis acetylene synthesizes carbon-coated iron-tri-ferrous carbide magnetic nanoparticle.Also, when by for growth temperature, growth Between, the control of gas ratio, realize to synthesized carbon-coated iron-tri-ferrous carbide magnetic nanoparticle partial size and dispersion effect Accuracy controlling it is comprehensive so that tri-ferrous carbide magnetic nanoparticle partial size is small, is uniformly dispersed for synthesized carbon-coated iron- It can be good.
(2) compared with the preparation method of CN106732598A carbon-encapsulated iron nanocatalyst, the present invention has outstanding Substantive distinguishing features and marked improvement are:
For carbon-encapsulated iron or iron-base magnetic nano particle, good stability is to guarantee its catalysis, absorption and magnetic The premise that performance gives full play to, therefore, the degree of graphitization and thermal stability for improving carbon coating layer are carbon-encapsulated irons or iron-based One of the target of magnetic nanoparticle study on the synthesis.CN106732598A ultrasound and stirring under, by iron nitrate solution by It is added dropwise to the mixed solution of sucrose and hydrazine hydrate, dries and amorphous carbon-coated iron catalyst is made in carbonization under nitrogen protection Nano particle.Due to the method using pyrolysis, solid-state carbon source forms carbon coating layer by adsorption -diffusion-precipitating growth mechanism, It needs to overcome high energy barrier, to be difficult to give full play to the catalytic activity of iron catalyst particle, leads to the carbon packet of synthesis Amorphous state is presented in coating, and poor compactness and thermo oxidative stability are difficult to form good guarantor to the iron nano-particle of core Shield effect, reduces its service performance.
The present invention in the design process, has fully considered how to avoid amorphous carbon coating layer to carbon-encapsulated iron or iron-based magnetic Property nano particle performance adversely affect, so that catalyst is played good catalytic activity to make carbon coating layer have in order to reach Have the purpose compared with high graphitization degree, use ironic citrate as source of iron, potassium bromide as carrier, pass sequentially through freeze-drying, Ball milling, calcining, reduction processing step obtain dispersibility and the iron catalyst particle that has good uniformity, thereby guarantee that its catalysis is lived Property gives full play to.Then, carbon coating layer is obtained using the chemical vapor deposition of acetylene, synthesis mechanism is that gaseous carbon source is being urged Carbon atom is decomposited under agent effect and enters catalytic inner, and the carbon atom for reaching saturation state is analysed along catalyst particular crystal plane Carbon coating layer is formed out, it then follows gas-liquid-solid growth mechanism, the energy barrier for needing to overcome is low, therefore the catalysis of catalyst Activity is given full play to, to be formed by carbon coating layer with higher crystallization degree, so that carbon-coated iron-carbonization Three ferromagnetic nanoparticles have better stability, can satisfy different application field and the stability in use of the material is wanted It asks.
(3) a kind of method of the compound of carbon nanotube/graphite coat iron nano-particle is prepared with CN104785777A It compares, the substantive distinguishing features outstanding and marked improvement that the present invention has are:
Before carbon-encapsulated iron or iron-base magnetic nano particle are widely used in fields such as electricity, magnetics, optics, calorifics Scape, above-mentioned field propose harsh requirement to the quality of material, it is desirable that one of be carbon-encapsulated iron nano particle purity is high, Impurity content is few.CN104785777A is first with Co (Fe, Ni) the particle synthesizing carbon nanotubes being deposited on silicon wafer, with anti- The progress answered, ferrocene are released and are decomposited as source of iron iron nano-particle and assemble on the carbon nanotubes, pass through plasma Method synthesizing carbon nanotubes/graphite coat iron nano-particle of body enhancing chemical vapor deposition.For carbon-encapsulated iron nanometer For the use of grain, which is that the carbon nanotube synthesized at first not can be removed as impurity phase there are insoluble problem. Since carbon nanotube has good structural stability, will not disappear with the synthesis of carbon-encapsulated iron nano particle and all, and With the progress of reaction, carbon nanotube continued growth leads to have content higher, difficult in carbon-encapsulated iron nano particle synthetic product With the carbon nanotube impurity of removal, the purity of carbon-encapsulated iron nano particle has been seriously affected, has reduced its service performance.
In the method for the present invention design process, using prepare high-purity carbon-coated iron-tri-ferrous carbide magnetic nanoparticle as One of target, has fully considered the issues of purification of synthesized product, and innovative proposes using potassium bromide as carrier material Material.The fusing point of potassium bromide is 734 DEG C, in the lower synthesis temperature section of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle It is with good stability；Potassium bromide is soluble easily in water, can be by simply washing and centrifuge separation is easily removed.Therefore, originally Inventive method can prepare carbon-coated iron-tri-ferrous carbide magnetic nanoparticle of high-purity, meet different field to the product Service performance demand.
(4) with CN102990075A is a kind of prepare the method for Carbon-coated iron nanoparticles compared with, the present invention has outstanding Substantive distinguishing features and marked improvement are:
For carbon-encapsulated iron or iron-base magnetic nano particle, good stability is to guarantee its catalysis, absorption and magnetic The premise that performance gives full play to, therefore, the degree of graphitization and thermal stability for improving carbon coating layer are carbon-encapsulated irons or iron-based One of the target of magnetic nanoparticle study on the synthesis.CN102990075A obtains organic carbon using liquid alkane backflow method and wraps up FexOy, follow-up heat treatment process, which is equal to, is pyrolyzed solid-state carbon source formation carbon-encapsulated iron nano particle, in the process, You Jigu State carbon source forms carbon coating layer by decomposition-adsorption -diffusion-precipitating growth mechanism, needs to overcome high energy barrier, from And be difficult to give full play to the catalytic activity of iron catalyst particle, cause the carbon coating layer of synthesis that amorphous state, poor cause is presented Close property and thermo oxidative stability are difficult to form good protective effect to the iron nano-particle of core, reduce its service performance.
The present invention in the design process, has fully considered how to avoid amorphous carbon coating layer to carbon-encapsulated iron or iron-based magnetic Property nano particle performance adversely affect, so that catalyst is played good catalytic activity to make carbon coating layer have in order to reach Have the purpose compared with high graphitization degree, use ironic citrate as source of iron, potassium bromide as carrier, pass sequentially through freeze-drying, Ball milling, calcining, reduction processing step obtain dispersibility and the iron catalyst particle that has good uniformity, thereby guarantee that its catalysis is lived Property gives full play to.Then, carbon coating layer is obtained using the chemical vapor deposition of acetylene, synthesis mechanism is that gaseous carbon source is being urged Carbon atom is decomposited under agent effect and enters catalytic inner, and the carbon atom for reaching saturation state is analysed along catalyst particular crystal plane Carbon coating layer is formed out, it then follows gas-liquid-solid growth mechanism, the energy barrier for needing to overcome is low, therefore the catalysis of catalyst Activity is given full play to, to be formed by carbon coating layer with higher crystallization degree, so that carbon-coated iron-carbonization Three ferromagnetic nanoparticles have better stability, can satisfy different application field and the stability in use of the material is wanted It asks.
(5) compared with the hydrothermal preparing process of CN102784913A carbon-encapsulated iron nano particle, protrusion that the present invention has Substantive distinguishing features and marked improvement be:
Carbon-encapsulated iron or iron-base magnetic nano particle are remembered in adsorbent material, the magnetic of pharmaceutical carrier, heavy metal or organic dyestuff The fields such as material are recorded in use, all proposing strict requirements to the dispersibility of the partial size of the material and particle. CN102784913A prepares carbon-encapsulated iron nano particle using hydro-thermal method, and ferric nitrate and glucose solution are mixed in proportion It is even, reaction kettle is subsequently transferred in reaction 1-24 hours of 160-220 DEG C of temperature, in inert gas shielding after being centrifuged, drying Lower calcining obtains carbon-encapsulated iron nano particle.The patent is solution, at high operating temperatures, ferric nitrate due to hydro-thermal reaction environment It can increase in the iron catalyst decomposited, and warm-up movement occur in liquid solvent, due to van der Waals interaction, necessarily cause A large amount of iron catalyst nanoparticles are reunited and are bonded together and partial size is caused to increase.According to existing result of study, catalyst Particle size seriously affects its catalytic performance: catalyst particle size increases, and catalytic performance significantly reduces.Therefore, the iron of reunion is received Rice grain catalytic performance seriously reduces, and leads to that the carbon-encapsulated iron nanocomposite partial size of synthesis is big, bad dispersibility, partial size point Cloth is uneven and performance is poor.
The present invention in the design process, has fully considered how to improve carbon-coated iron-tri-ferrous carbide magnetic nanoparticle Dispersibility and uniformity, it is prepared carbon-coated in existing invention in order to solve and then the problem of improve its service performance Iron-tri-ferrous carbide magnetic nanoparticle bad dispersibility, particle diameter distribution unevenly lead to the problem of service performance difference, and innovative mentions Go out and ironic citrate is loaded to by potassium bromide surface by the method for freeze-drying, acquisition is evenly distributed on potassium bromide carrier surface The ironic citrate particle as ferrous metal source, be in detail, by uniformly mixed potassium bromide and citric acid solution cold Dry composite under jelly state obtains the work for being dispersed in potassium bromide carrier surface by subsequent ball milling, calcining, reducing process For the ironic citrate particle in ferrous metal source, which is iron catalyst particle, also, by adjusting potassium bromide and Concentration proportioning and subsequent ball milling, calcining, the reducing process of citric acid solution realize accurate adjust to the partial size of iron catalyst particle Control.In addition, its catalytic performance is given full play in order to avoid the reunion of iron catalyst particle, using the method for chemical vapor deposition Catalytic pyrolysis acetylene synthesizes carbon-coated iron-tri-ferrous carbide magnetic nanoparticle.Also, when by for growth temperature, growth Between, the control of gas ratio, realize to synthesized carbon-coated iron-tri-ferrous carbide magnetic nanoparticle partial size and dispersion effect Accuracy controlling it is comprehensive so that tri-ferrous carbide magnetic nanoparticle partial size is small, is uniformly dispersed for synthesized carbon-coated iron- It can be good.
(6) compared with a kind of magnetic superfine iron particle of charcoal cladding of CN1935415A and its manufacturing method, the present invention has Substantive distinguishing features outstanding and marked improvement be:
CN1935415A uses the method for ball milling by nano ferriferrous oxide and interleaving agent (sodium chloride, potassium chloride, chlorination Calcium) mixing, and utilize the magnetic superfine iron particle of chemical vapor deposition method for preparing carbon/carbon cladding.Its technique exists apparent unreasonable Property: since there are stronger Van der Waals forces between nano ferriferrous oxide, only by simple ball-milling technology, it is difficult to avoid receiving The agglomeration of rice corpuscles simultaneously realizes its being uniformly distributed on interleaving agent surface, therefore, directly results in the dispersion of iron catalyst Property it is poor, particle diameter distribution section is big, thus synthesis charcoal cladding magnetic superfine iron particle partial size be within the scope of 50~400nm compared with Simultaneously the phenomenon that mutually reuniting is presented in big particle diameter distribution section, seriously reduces its service performance.
The present invention in the design process, has fully considered how to improve carbon-coated iron-tri-ferrous carbide magnetic nanoparticle Dispersibility and uniformity, it is prepared carbon-coated in existing invention in order to solve and then the problem of improve its service performance Iron-tri-ferrous carbide magnetic nanoparticle bad dispersibility, particle diameter distribution unevenly lead to the problem of service performance difference, and innovative mentions Go out and ironic citrate is loaded to by potassium bromide surface by the method for freeze-drying, acquisition is evenly distributed on potassium bromide carrier surface The ironic citrate particle as ferrous metal source, be in detail, by uniformly mixed potassium bromide and citric acid solution cold Dry composite under jelly state obtains the work for being dispersed in potassium bromide carrier surface by subsequent ball milling, calcining, reducing process For the ironic citrate particle in ferrous metal source, which is iron catalyst particle, also, by adjusting potassium bromide and Concentration proportioning and subsequent ball milling, calcining, the reducing process of citric acid solution realize accurate adjust to the partial size of iron catalyst particle Control.In addition, its catalytic performance is given full play in order to avoid the reunion of iron catalyst particle, using the method for chemical vapor deposition Catalytic pyrolysis acetylene synthesizes carbon-coated iron-tri-ferrous carbide magnetic nanoparticle.Also, when by for growth temperature, growth Between, the control of gas ratio, realize to synthesized carbon-coated iron-tri-ferrous carbide magnetic nanoparticle partial size and dispersion effect Accuracy controlling it is comprehensive so that tri-ferrous carbide magnetic nanoparticle partial size is small, is uniformly dispersed for synthesized carbon-coated iron- It can be good.
(7) it is used to adsorb the preparation method and applications method of the adsorbent of dyestuff, present invention tool with CN104117339A Substantive distinguishing features outstanding and marked improvement be:
(a) there is substantive differences for the preparation process of the two and synthesis mechanism.
CN104117339A discloses a kind of ferromagnetic using iron catalyst decomposition glucose synthesis carbon coating by hydro-thermal method Property nano particle adsorbent preparation method, it is intended to the physical and chemical properties for solving magnetic adsorbent in the prior art are poor, magnetic The problem of performance is weak, and use scope is narrow, is not easily recycled in as adsorbent use process, easily causes secondary pollution. Iron catalyst is supported on sodium chloride surface by CN104117339A, is proportionally added into glucose and is made containing iron catalyst, chlorination The suspension of sodium, glucose is transferred to later using polytetrafluoroethylene (PTFE) as in the reaction kettle of substrate, in 180~220 DEG C of Muffle furnace In, constant temperature keeps 9~12h, obtains carbon-encapsulated iron nano particle.Its process mechanism is, in reaction kettle confined space, passes through Heat suspension, create the reaction environment of high temperature and pressure, glucose because of dehydration, be carbonized and iron be coated on by suction-operated and urge Agent surface.Its defective workmanship is, dissolution of this method due to carrier sodium chloride, the warm-up movement of iron nano-particle and mutually group It is poly-, can not partial size to carbon-encapsulated iron nano particle and dispersibility carry out accuracy controlling.
The present invention is that the iron catalyst particle using chemical vapour deposition technique using uniform load on potassium bromide surface cracks Gaseous carbon source acetylene obtains carbon-coated iron-tri-ferrous carbide magnetic nanoparticle method, solves carbon coating in the prior art The problem that iron-tri-ferrous carbide magnetic nanoparticle purity is low, controllability, the stability of dispersibility of particle and partial size are low.This Invention uses chemical vapour deposition technique, and iron oxide-potassium bromide catalyst presoma is laid in quartzy Noah's ark, hydrogen is successively passed through The gaseous mixture of gas, acetylene and argon gas is catalyzed acetylene on the iron catalyst particle obtained by hydrogen reducing iron oxide Cracking reaction synthesizes carbon-coated iron-tri-ferrous carbide magnetic nanoparticle.Its mechanism of action is that gaseous carbon source is made in catalyst Carbon atom is decomposited under and enters catalytic inner, and the carbon atom for reaching saturation state is precipitated to be formed along catalyst particular crystal plane Carbon coating layer, it then follows gas-liquid-solid growth mechanism.The present invention utilizes the iron catalyst granular raw for being supported on potassium bromide surface Position deposition carbon forms carbon coating layer, and by control synthesis temperature and the technological parameters such as time and acetylene-argon gas ratio, realizes For carbon-coated iron-tri-ferrous carbide magnetic nanoparticle purity, the accuracy controlling of crystallization degree, partial size and dispersibility, from And synthetic effect is more preferably.
(b) there are significant differences for the magnetic property that preparation process both causes.
In order to prepare iron catalyst particle, CN104117339A uses deposition-precipitation, chlorine is added dropwise in sodium hydroxide Change in water solution, is ferric hydroxide colloid and sodium-chloride water solution after reaction, directly dries and utilize in drying box later Mortar hand lapping.During the drying process, since the difference of the colloidal state of iron hydroxide and the dissolved state of sodium chloride causes There are sequencings for the drying of the two so as to cause lamination, and then will appear the phenomenon that iron hydroxide is reunited, and then make Iron hydroxide being uniformly distributed on sodium chloride surface difficult to realize is simply ground with agate mortar, this will lead to subsequent acquisition Iron catalyst grain diameter is big and is unevenly distributed, and catalytic performance is bad, synthesized carbon-encapsulated ferromagnetic nano grain diameter Greatly, degree of graphitization is low, bad dispersibility, and then causes its magnetic property poor, it is difficult to meet the use of carbon-coated metallic nano-particles It is required that.
For the present invention in order to obtain uniform particle sizes, well dispersed iron catalyst particle, innovative proposing passes through freezing Ironic citrate is loaded to potassium bromide surface by dry method, by uniformly mixed potassium bromide and citric acid solution in freezing shape Dry composite under state, and it is next uniform using ball milling mixing, by subsequent calcination, reducing process, can obtain evenly dispersed Iron catalyst particle on potassium bromide surface, to be conducive to giving full play to for iron catalyst catalytic activity, so that the carbon of synthesis The iron of cladding-tri-ferrous carbide magnetic nanoparticle partial size is small, degree of graphitization is high, good dispersion, effectively increases magnetic property, energy Enough meet carbon-coated iron-tri-ferrous carbide magnetic nanoparticle in numerous areas such as adsorbent material, magnetic medicine carrier materials Requirement.
It can be seen that the method for the present invention is compared with prior art CN104117339A, in mentality of designing, process mechanism, conjunction There is substantive difference at effect and innovative aspect, and has significant progress.
(8) with CN101710512A graphene and carbon-encapsulated ferromagnetic nano metal composite material and preparation method phase Than, the substantive distinguishing features outstanding and marked improvement that the present invention has are:
CN101710512A uses graphene oxide as carrier, obtains graphene and carbon coating by chemical vapor deposition Ferromagnetic nano metal composite material.It, will not be with since used graphene has nanoscale and good stability The progress of reaction and die away, and there are extremely strong Van der Waals force between carbon-encapsulated ferromagnetic nano particle, both cause It mixes and is difficult to remove by the method for purification.Therefore, for carbon-encapsulated ferromagnetic nano particle, graphene is one It plants impurity and content is very high.Meanwhile as a kind of non-ferromagnetic substance, a large amount of presence of graphene necessarily result in synthetic product The great reduction of magnetic property, seriously reduce the service performance of carbon-encapsulated ferromagnetic nano particle.
In the method for the present invention design process, using prepare high-purity carbon-coated iron-tri-ferrous carbide magnetic nanoparticle as One of target, has fully considered the issues of purification of synthesized product, and innovative proposes using potassium bromide as carrier material Material.The fusing point of potassium bromide is 734 DEG C, in the lower synthesis temperature section of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle It is with good stability；Potassium bromide is soluble easily in water, can be by simply washing and centrifuge separation is easily removed.Therefore, originally Inventive method can prepare carbon-coated iron-tri-ferrous carbide magnetic nanoparticle of high-purity, meet different field to the product Service performance demand.
Compared with prior art, the marked improvement of the method for the present invention is as follows:
(1) present invention is evenly distributed on bromine by freeze drying process acquisition using ironic citrate and potassium bromide as raw material The ironic citrate particle as ferrous metal source for changing potassium carrier surface obtains oxygen so that ironic citrate decomposes by calcining after ball milling Change iron-potassium bromide catalyst presoma, passes through hydrogen reducing iron oxide and acetylene-argon gas mixed gas chemical vapor deposition system Carbon-coated iron-tri-ferrous carbide magnetic nanoparticle is obtained, novelty is: (a) firstly, realizing using freeze drying process As ferrous metal source ironic citrate particle potassium bromide surface uniform, controlled distribution；Secondly, after matching when to solution concentration Continuous ball milling, calcining, the adjustment of reducing process, realize the accuracy controlling to iron catalyst partial size；Again, in chemical vapor deposition During, to the adjustment of generated time, temperature and acetylene-argon gas ratio, comprehensive function as a result, realizing to carbon-coated The accuracy controlling of iron-tri-ferrous carbide magnetic nanoparticle partial size, dispersibility and crystallization degree, obtain partial size it is small and uniform, The high carbon-coated iron-tri-ferrous carbide magnetic nanoparticle of good dispersion, crystallization degree；(b) using potassium bromide as carrier material Material, can be by simply washing and centrifuge separation is easily removed, and carbon-coated iron-tri-ferrous carbide that high-purity has been made is magnetic Nano particle, excellent combination property.
(2) equipment used in the method for the present invention is simple, and raw material are easy to get, and process flow is simple, and production cost is low, easily It is produced in batches in realizing, the fields such as electricity, magnetics, optics and biomedicine can be met to carbon-clad metal magnetic nanoparticle Use demand.
(3) the available purity of the present invention reaches 97~99.5%, and saturation magnetization reaches 30.53~94.80emu/g, Coercivity reaches 458.83~821.33Oe, uniform particle sizes, good dispersion, the high carbon-coated iron-tri-ferrous carbide of crystallization degree Magnetic nanoparticle product.
Detailed description of the invention
Present invention will be further explained below with reference to the attached drawings and examples.
Fig. 1 is carbon-coated iron-tri-ferrous carbide magnetic nanoparticle X-ray diffraction obtained by the embodiment of the present invention 2 Figure.
Fig. 2 is that carbon-coated iron-tri-ferrous carbide magnetic nanoparticle scanning electron obtained by the embodiment of the present invention 2 is aobvious Micro mirror photo.
Fig. 3 is the low resolved transmittance of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle obtained by the embodiment of the present invention 2 Electron micrograph.
Fig. 4 is the transmission of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle high-resolution obtained by the embodiment of the present invention 2 Electron micrograph.
Fig. 5 is carbon-coated iron-tri-ferrous carbide magnetic nanoparticle hysteresis loop obtained by the embodiment of the present invention 2.
Specific embodiment
Embodiment 1
The first step prepares iron oxide-potassium bromide catalyst presoma:
It is with mass percent concentration by the five citric acid monohydrate water solutions that mass percent concentration is 3% first 10.03% kbr aqueous solution is mixed to form mixed solution, it is ensured that wherein iron and the mass ratio of potassium bromide are 0.05: 1, are used Magnetic heating stirrer carries out heating stirring 4h to above-mentioned mixed solution in 70 DEG C of revolving speeds with 500rpm, is then transferred to plastics Test tube is placed in freeze drying box, is cooled to -50 DEG C with the cooling rate of 20 DEG C/min, above-mentioned mixed solution is frozen into solid-state Continue in freeze drying box the dry 48h under the vacuum of 1.3Pa afterwards, then from taken out in plastic test tube it is freeze-dried after obtain The ironic citrate particle as ferrous metal source for being evenly distributed on potassium bromide carrier surface obtained, is existed using planetary ball mill 30min is ground under 800rpm, the lemon as ferrous metal source for being evenly distributed on potassium bromide carrier surface that will be obtained after ball milling Sour iron particle is put into Ovenized resistance furnace, in air atmosphere 700 DEG C of calcining 90min, and oxidation is made after being cooled to room temperature Iron-potassium bromide catalyst presoma；
Second step prepares carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product:
Use chemical vapour deposition technique that magnetic nanoparticle outer layer is made as carbon-coating, core is that iron and tri-ferrous carbide constitute core The carbon-coated iron of the heart-tri-ferrous carbide magnetic nanoparticle product, the specific process is as follows:
Iron oxide-potassium bromide catalyst presoma of above-mentioned first step preparation is taken to be laid in quartzy Noah's ark, by square quartz Boat is placed in the flat-temperature zone of horizontal pipe furnace and closes tube furnace, and extracting the air in tube furnace by mechanical pump makes in tube furnace Vacuum degree reaches -0.1MPa, and argon gas is then slowly introducing into tube furnace with the flow velocity of 30mL/min, when vacuum degree in tube furnace After being zero, adjustment argon flow is 300mL/min and tube furnace is warming up to going back for iron oxide with the heating rate of 10 DEG C/min 900 DEG C of former temperature after reaching the reduction temperature, closes argon gas and is passed through flow at once as the hydrogen of 200mL/min, and keep 2h Iron oxide is reduced to iron catalyst particle, then adjusts furnace temperature to carbon-coated iron-tri-ferrous carbide magnetic nanoparticle growth It 300 DEG C of temperature, closes hydrogen and is passed through the argon gas of the acetylene gas that flow is 10mL/min and certain flow at once, it is ensured that is above-mentioned The flow-rate ratio of acetylene gas and argon gas is 1:15 in the mixed gas of acetylene gas and argon gas, and heat preservation 10min carries out carbon-coated The growth of iron-tri-ferrous carbide magnetic nanoparticle, in above-mentioned 10min insulating process, carbon atom and iron that acetylene decomposition obtains Catalyst granules is interacted, and has been obtained carbon-coated iron-tri-ferrous carbide magnetic nanoparticle, has finally been closed acetylene gas Body simultaneously adjusts the flow of argon gas to 200mL/min, and stopping diamond heating being cooled to reaction product under argon atmosphere protection Thus the carbon-coated iron-tri-ferrous carbide magnetic nanoparticle for being evenly distributed on potassium bromide carrier surface is made in room temperature；
By the carbon-coated iron-tri-ferrous carbide magnetic nanoparticle obtained above for being evenly distributed on potassium bromide carrier surface It is added to the suspension for forming that concentration is 1mg/mL in distilled water, using ultrasonic disperse instrument with the frequency of 50kHz to above-mentioned suspension Liquid carries out ultrasonic cleaning 40min, above-mentioned suspension is transferred in centrifuge tube later and on supercentrifuge with The revolving speed of 10000rpm is centrifugated 20min, and centrifuge tube is placed in electric heating with after the supernatant in rubber head dropper removal centrifuge tube In 70 DEG C of drying 8h in air dry oven, it is carbon-coating that magnetic nanoparticle outer layer, which is thus made, and core is iron and tri-ferrous carbide structure At carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product of core, purity reaches 99.5%, and saturation magnetization reaches 94.8Oemu/g, coercivity reach 458.83Oe.
Embodiment 2
The first step prepares iron oxide-potassium bromide catalyst presoma:
It is with mass percent concentration by the five citric acid monohydrate water solutions that mass percent concentration is 2% first 11.14% kbr aqueous solution is mixed to form mixed solution, it is ensured that wherein iron and the mass ratio of potassium bromide are 0.03: 1, are used Magnetic heating stirrer carries out heating stirring 3h to above-mentioned mixed solution in 60 DEG C of revolving speeds with 400rpm, is then transferred to plastics Test tube is placed in freeze drying box, is cooled to -30 DEG C with the cooling rate of 15 DEG C/min, above-mentioned mixed solution is frozen into solid-state Continue in freeze drying box the dry 36h under the vacuum of 8Pa afterwards, then from taken out in plastic test tube it is freeze-dried after obtain The ironic citrate particle as ferrous metal source for being evenly distributed on potassium bromide carrier surface, existed using planetary ball mill 20min is ground under 700rpm, the lemon as ferrous metal source for being evenly distributed on potassium bromide carrier surface that will be obtained after ball milling Sour iron particle is put into Ovenized resistance furnace, in air atmosphere 550 DEG C of calcining 60min, and oxidation is made after being cooled to room temperature Iron-potassium bromide catalyst presoma；
Second step prepares carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product:
Use chemical vapour deposition technique that magnetic nanoparticle outer layer is made as carbon-coating, core is that iron and tri-ferrous carbide constitute core The carbon-coated iron of the heart-tri-ferrous carbide magnetic nanoparticle product, the specific process is as follows:
Iron oxide-potassium bromide catalyst presoma of above-mentioned first step preparation is taken to be laid in quartzy Noah's ark, by square quartz Boat is placed in the flat-temperature zone of horizontal pipe furnace and closes tube furnace, and extracting the air in tube furnace by mechanical pump makes in tube furnace Vacuum degree reaches -0.08MPa, and argon gas is then slowly introducing into tube furnace with the flow velocity of 20mL/min, when vacuum in tube furnace After degree is zero, adjustment argon flow is 200mL/min and tube furnace is warming up to going back for iron oxide with the heating rate of 6 DEG C/min 750 DEG C of former temperature after reaching the reduction temperature, closes argon gas and is passed through flow at once as the hydrogen of 150mL/min, and keep 1h Iron oxide is reduced to iron catalyst particle, then adjusts furnace temperature to carbon-coated iron-tri-ferrous carbide magnetic nanoparticle growth It 400 DEG C of temperature, closes hydrogen and is passed through the argon gas of the acetylene gas that flow is 20mL/min and certain flow at once, it is ensured that is above-mentioned The flow-rate ratio of acetylene gas and argon gas is 1:10 in the mixed gas of acetylene gas and argon gas, and heat preservation 30min carries out carbon-coated The growth of iron-tri-ferrous carbide magnetic nanoparticle, in above-mentioned 30min insulating process, carbon atom and iron that acetylene decomposition obtains Catalyst granules is interacted, and has been obtained carbon-coated iron-tri-ferrous carbide magnetic nanoparticle, has finally been closed acetylene gas Body simultaneously adjusts the flow of argon gas to 150mL/min, and stopping diamond heating being cooled to reaction product under argon atmosphere protection Thus the carbon-coated iron-tri-ferrous carbide magnetic nanoparticle for being evenly distributed on potassium bromide carrier surface is made in room temperature；
By the carbon-coated iron-tri-ferrous carbide magnetic nanoparticle obtained above for being evenly distributed on potassium bromide carrier surface It is added to the suspension for forming that concentration is 2mg/mL in distilled water, using ultrasonic disperse instrument with the frequency of 30kHz to above-mentioned suspension Liquid carries out ultrasonic cleaning 30min, and above-mentioned suspension is transferred in centrifuge tube and on supercentrifuge with 9000rpm later Revolving speed be centrifugated 15min, with centrifuge tube is placed in electric heating forced air drying after the supernatant in rubber head dropper removal centrifuge tube In 60 DEG C of drying 7h in case, it is carbon-coating that magnetic nanoparticle outer layer, which is thus made, and core is that iron and tri-ferrous carbide constitute core Carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product, purity reach 98.2%, and saturation magnetization reaches 49.53emu/g, coercivity reach 579.63Oe.
Fig. 1 is carbon-coated iron-tri-ferrous carbide magnetic nanoparticle X-ray diffractogram obtained by the present embodiment.Figure The middle angle of diffraction corresponds to (002) crystal face of carbon for the characteristic peak at 26.2 °, and the characteristic peak at 44.7 ° corresponds to (110) crystal face of iron, Characteristic peak at 37.8 °, 39.8 °, 40.7 °, 43.8 °, 45.1 °, 45.9 °, 49.2 ° and 58.1 ° respectively corresponds tri-ferrous carbide (021), (200), (120), (210), (103), (211), (122) and (130) crystal face, this show synthesis product only by carbon, The three kinds of object phase compositions of iron and tri-ferrous carbide, the potassium bromide as carrier can be completely removed, to synthesize the carbon of high-purity The iron of cladding-tri-ferrous carbide magnetic nanoparticle.
Fig. 2 is carbon-coated iron-tri-ferrous carbide magnetic nanoparticle scanning electron microscope obtained by the present embodiment Photo.It is shown in figure, iron-tri-ferrous carbide magnetic nanoparticle surface has successfully coated carbon-coating, iron-tri-ferrous carbide does not occur The exposed phenomenon of particle；Obtained carbon-coated iron-tri-ferrous carbide magnetic nanoparticle uniform particle sizes has good dispersion Property, without apparent agglomeration, to be conducive to the abundant hair of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle performance It waves.
Fig. 3 is the low Resolution Transmission Electron of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle obtained by the present embodiment Microscope photo.It can be seen from the figure that synthesized carbon-coated iron-tri-ferrous carbide magnetic nanoparticle has apparent core Shell structure, core are iron-tri-ferrous carbide magnetic nanoparticle of torispherical, and outside is the carbon coating layer of 20-40nm, the carbon packet Coating can effectively prevent the reunion of iron-tri-ferrous carbide magnetic nanoparticle, and good protective effect is formed to it, thus anti- Only it is corroded and is aoxidized by external environment.
Fig. 4 is carbon-coated iron-tri-ferrous carbide magnetic nanoparticle high-resolution transmitted electron obtained by the present embodiment Microscope photo.It can be seen from the figure that forming close interface between carbon coating layer and iron-tri-ferrous carbide magnetic nanoparticle In conjunction with, and carbon-coating crystallization degree is good, so that synthesized carbon-coated iron-tri-ferrous carbide magnetic nanoparticle has Good thermo oxidative stability.
Fig. 5 is carbon-coated iron-tri-ferrous carbide magnetic nanoparticle hysteresis loop obtained by the present embodiment.From figure As can be seen that with the cyclically-varying of magnetic field strength, synthesized carbon-coated iron-tri-ferrous carbide magnetic nanoparticle magnetic Change intensity and complete square ring is presented, shows apparent hysteresis；Its saturation magnetization is 49.53emu/g, coercive Power is 579.63Oe, shows good magnetic property.
Embodiment 3
The first step prepares iron oxide-potassium bromide catalyst presoma:
It is with mass percent concentration by the five citric acid monohydrate water solutions that mass percent concentration is 1% first 16.7% kbr aqueous solution is mixed to form mixed solution, it is ensured that wherein iron and the mass ratio of potassium bromide are 0.01: 1, are used Magnetic heating stirrer carries out heating stirring 2h to above-mentioned mixed solution in 50 DEG C of revolving speeds with 300rpm, is then transferred to plastics Test tube is placed in freeze drying box, is cooled to -10 DEG C with the cooling rate of 5 DEG C/min, above-mentioned mixed solution is frozen into solid-state Continue in freeze drying box afterwards under the vacuum of 13.0Pa it is dry for 24 hours, then from taken out in plastic test tube it is freeze-dried after The ironic citrate particle as ferrous metal source for being evenly distributed on potassium bromide carrier surface obtained, is existed using planetary ball mill 10min is ground under 600rpm, the lemon as ferrous metal source for being evenly distributed on potassium bromide carrier surface that will be obtained after ball milling Sour iron particle is put into Ovenized resistance furnace, in air atmosphere 400 DEG C of calcining 30min, and oxidation is made after being cooled to room temperature Iron-potassium bromide catalyst presoma；
Second step prepares carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product:
Use chemical vapour deposition technique that magnetic nanoparticle outer layer is made as carbon-coating, core is that iron and tri-ferrous carbide constitute core The carbon-coated iron of the heart-tri-ferrous carbide magnetic nanoparticle product, the specific process is as follows:
Iron oxide-potassium bromide catalyst presoma of above-mentioned first step preparation is taken to be laid in quartzy Noah's ark, by square quartz Boat is placed in the flat-temperature zone of horizontal pipe furnace and closes tube furnace, and extracting the air in tube furnace by mechanical pump makes in tube furnace Vacuum degree reaches -0.05MPa, and argon gas is then slowly introducing into tube furnace with the flow velocity of 5mL/min, when vacuum degree in tube furnace After being zero, adjustment argon flow is 100mL/min and tube furnace is warming up to the reduction of iron oxide with the heating rate of 2 DEG C/min It 600 DEG C of temperature, after reaching the reduction temperature, closes argon gas and is passed through flow at once as the hydrogen of 100mL/min, and keep 0.5h Iron oxide is reduced to iron catalyst particle, then adjusts furnace temperature to carbon-coated iron-tri-ferrous carbide magnetic nanoparticle growth It 450 DEG C of temperature, closes hydrogen and is passed through the argon gas of the acetylene gas that flow is 30mL/min and certain flow at once, it is ensured that is above-mentioned The flow-rate ratio of acetylene gas and argon gas is 1:5 in the mixed gas of acetylene gas and argon gas, and heat preservation 60min carries out carbon-coated The growth of iron-tri-ferrous carbide magnetic nanoparticle, in above-mentioned 60min insulating process, carbon atom and iron that acetylene decomposition obtains Catalyst granules is interacted, and has been obtained carbon-coated iron-tri-ferrous carbide magnetic nanoparticle, has finally been closed acetylene gas Body simultaneously adjusts the flow of argon gas to 100mL/min, and stopping diamond heating being cooled to reaction product under argon atmosphere protection Thus the carbon-coated iron-tri-ferrous carbide magnetic nanoparticle for being evenly distributed on potassium bromide carrier surface is made in room temperature；
By the carbon-coated iron-tri-ferrous carbide magnetic nanoparticle obtained above for being evenly distributed on potassium bromide carrier surface It is added to the suspension for forming that concentration is 3mg/mL in distilled water, using ultrasonic disperse instrument with the frequency of 20kHz to above-mentioned suspension Liquid carries out ultrasonic cleaning 20min, and above-mentioned suspension is transferred in centrifuge tube and on supercentrifuge with 8000rpm later Revolving speed be centrifugated 10min, with centrifuge tube is placed in electric heating forced air drying after the supernatant in rubber head dropper removal centrifuge tube In 50 DEG C of drying 6h in case, it is carbon-coating that magnetic nanoparticle outer layer, which is thus made, and core is that iron and tri-ferrous carbide constitute core Carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product, purity reach 97%, and saturation magnetization reaches 30.53emu/ G, coercivity reach 821.33Oe.
Raw material involved in above-described embodiment are commercially available, and equipment used and technique are this technology necks Known to the technical staff in domain.

Claims (1)

1. carbon-coated iron-tri-ferrous carbide magnetic nanoparticle preparation method, it is characterised in that: by ironic citrate and potassium bromide Mixed solution, obtained by Freeze Drying Technique and be evenly distributed on the citric acid as ferrous metal source of potassium bromide carrier surface Iron particle obtains iron oxide-potassium bromide catalyst presoma using calcining, magnetism then is made using chemical vapour deposition technique Nano particle outer layer is carbon-coating, and core is carbon-coated iron-tri-ferrous carbide magnetic Nano that iron and tri-ferrous carbide constitute core Granule product, the specific steps are as follows:
The first step prepares iron oxide-potassium bromide catalyst presoma:
It is first 10.03 by five citric acid monohydrate water solutions and mass percent concentration that mass percent concentration is 1~3% ~16.7% kbr aqueous solution is mixed to form mixed solution, it is ensured that wherein iron and the mass ratio of potassium bromide are 0.01~0.05 : 1, heating stirring 2 is carried out to above-mentioned mixed solution in 50~70 DEG C of revolving speeds with 300~500rpm using magnetic heating stirrer ~4h is then transferred to plastic test tube and is placed in freeze drying box, -10 are cooled to the cooling rate of 5~20 DEG C/min~- 50 DEG C, above-mentioned mixed solution be frozen into after solid-state continue in freeze drying box dry 24 under the vacuum of 1.3~13.0Pa~ 48h, then from taken out in plastic test tube it is freeze-dried after obtain be evenly distributed on potassium bromide carrier surface as iron gold The ironic citrate particle in category source grinds 10~30min using planetary ball mill at 600~800rpm, will obtain after ball milling The ironic citrate particle as ferrous metal source for being evenly distributed on potassium bromide carrier surface be put into Ovenized resistance furnace, Iron oxide-potassium bromide catalyst presoma is made in 400~700 DEG C of 30~90min of calcining under air atmosphere after being cooled to room temperature；
Second step prepares carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product:
Use chemical vapour deposition technique that magnetic nanoparticle outer layer is made as carbon-coating, core is that iron and tri-ferrous carbide constitute core Carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product, the specific process is as follows:
It takes iron oxide-potassium bromide catalyst presoma of above-mentioned first step preparation to be laid in quartzy Noah's ark, quartzy Noah's ark is set In horizontal pipe furnace flat-temperature zone and close tube furnace, by mechanical pump extract tube furnace in air make the vacuum in tube furnace Degree reaches -0.05~-0.1MPa, argon gas is then slowly introducing into tube furnace with the flow velocity of 5~30mL/min, when in tube furnace After vacuum degree is zero, adjustment argon flow is 100~300mL/min and with the heating rate of 2~10 DEG C/min by tube furnace liter Temperature is to 600~900 DEG C of reduction temperature of iron oxide, after reaching the reduction temperature, close argon gas and be passed through at once flow for 100~ The hydrogen of 200mL/min, and keep 0.5~2h that iron oxide is reduced to iron catalyst particle, furnace temperature is then adjusted to carbon coating Iron -300~450 DEG C of tri-ferrous carbide magnetic nanoparticle growth temperature, close hydrogen and be passed through flow at once as 10~30mL/ The acetylene gas of min and the argon gas of certain flow, it is ensured that acetylene gas and argon in the mixed gas of above-mentioned acetylene gas and argon gas The flow-rate ratio of gas is 1:5~15, and 10~60min of heat preservation carries out the growth of carbon-coated iron-tri-ferrous carbide magnetic nanoparticle, most Acetylene gas is closed afterwards and adjusts the flow of argon gas to 100~200mL/min, and stopping diamond heating making reaction product in argon gas It is cooled to room temperature under atmosphere protection, the carbon-coated iron-tri-ferrous carbide magnetic for being evenly distributed on potassium bromide carrier surface is thus made Property nano particle；
The carbon-coated iron obtained above for being evenly distributed on potassium bromide carrier surface-tri-ferrous carbide magnetic nanoparticle is added The suspension that concentration is 1~3mg/mL is formed into distilled water, using ultrasonic disperse instrument with the frequency of 20~50kHz to above-mentioned outstanding Supernatant liquid carries out 20~40min of ultrasonic cleaning, above-mentioned suspension is transferred in centrifuge tube later and on supercentrifuge with The revolving speed of 8000~10000rpm is centrifugated 10~20min, will centrifugation after removing the supernatant in centrifuge tube with rubber head dropper Pipe is placed in electric drying oven with forced convection in 50~70 DEG C of 6~8h of drying, and it is carbon-coating, core that magnetic nanoparticle outer layer, which is thus made, Constituting carbon-coated iron-tri-ferrous carbide magnetic nanoparticle product of core for iron and tri-ferrous carbide, purity reaches 97~ 99.5%, saturation magnetization reaches 30.53~94.8Oemu/g, and coercivity reaches 458.83~821.33Oe.
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