CN105771908B - A kind of magnetic silica core-shell composite material and preparation method thereof for heavy metal adsorption - Google Patents

A kind of magnetic silica core-shell composite material and preparation method thereof for heavy metal adsorption Download PDF

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CN105771908B
CN105771908B CN201610299995.5A CN201610299995A CN105771908B CN 105771908 B CN105771908 B CN 105771908B CN 201610299995 A CN201610299995 A CN 201610299995A CN 105771908 B CN105771908 B CN 105771908B
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cofe
sio
heavy metal
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CN105771908A (en
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丁新更
任春溶
付慧琴
杨辉
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Zhejiang University ZJU
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/103Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28009Magnetic properties
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28016Particle form
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/28Treatment of water, waste water, or sewage by sorption
    • C02F1/288Treatment of water, waste water, or sewage by sorption using composite sorbents, e.g. coated, impregnated, multi-layered

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Abstract

The magnetic silica core-shell composite material and preparation method thereof that the invention discloses a kind of for heavy metal adsorption, includes the following steps:(1) coprecipitation prepares CoFe2O4Nano particle;(2)Method is to CoFe obtained by step (1)2O4Nano particle carries out SiO2Cladding, obtains CoFe2O4@SiO2;(3) with gained CoFe2O4@SiO2It is raw material with 3 aminopropyl triethoxysilanes, the 4~8h that flows back at 60~100 DEG C obtains black suspension, the CoFe for being dried in vacuo amino modified after separation2O4@SiO2Chain nanocomposite.Technical solution of the present invention technique and easy to operate, it is environmental-friendly, different designs can be carried out for different heavy metals.Such material may be used on the processing of heavy metal containing sewage and radioactive wastewater.

Description

It is a kind of for the magnetic silica core-shell composite material of heavy metal adsorption and its preparation Method
Technical field
The present invention relates to heavy metal ion adsorbed, the fields such as heavy metal liquid waste processing and magnetic separation technique especially relate to And a kind of magnetic silica core of the amino functional with certain adsorption capacity of adsorption design for heavy metal ion Shell composite material new solution.
Background technology
Global economy is grown rapidly, and resource and environment has become the two large problems that the mankind are faced, and money is saved in environmental protection Source becomes the key subjects of the mankind.Water is human being's production and indispensable environmental resource element of living, nowadays heavy metal pollution Have become one of the environmental problem of most serious.Heavy metal is different from organic pollution, it cannot be biodegradable, and often exists It is accumulated in organism.Many heavy metal ion have been demonstrated toxic or carcinogen, greatly compromise the daily life of people It is living.Heavy metal containing wastewater treatment is related to people’s lives quality and living environment, and water reuse up to standard can be solved water resource Shortage, and heavy metal recovery can be utilized, therefore the improvement of heavy metal wastewater thereby and the research of purification of water quality reuse technology are mesh Preceding important topic.
Currently, main heavy metal containing wastewater treatment technology have ion-exchange, absorption method, chemical precipitation method, hyperfiltration, Membrane filter method etc., but they have oneself inherent advantages and limitation.Absorption method is at low cost, effect is good, operability By force, processing can generate the sewage of high quality, can be with desorption and regeneration etc. the advantages of, be that weight is effectively treated in one kind generally acknowledged at present The method of metallic wastewater.
Traditional adsorbent such as biological adsorption agent (bacterium, fungi, algae etc.), natural adsorbent (zeolite, diatomite, height Ridge soil, montmorillonite etc.), artificial synthesized adsorbent (activated carbon, carbon nanotube, SiO2、TiO2、ZrO2Deng).Although these are adsorbed Agent plays certain effect in terms of heavy metal containing wastewater treatment.But certain adsorbents such as nano-particle, adsorbing a huge sum of money Separation after category is highly difficult and takes a substantial amount of time, and limits the application of these adsorbents.If these are difficult to detach Adsorbent combine with magnetic property, synthesis has big specific surface area, and with the nano combined material of magnetic recovery capability Material will step major step in the application.
Magnetic adsorbent also deposits the weak problem of adsorption capacity, in order to improve the dispersibility and absorption property of adsorbent, Current research substantially may be summarized to be at 3 points:First is that ligand is carried out functionalization, such as mercaptan, organic amine, organic sulfide Object etc.;Second is that coated magnetic shell obtains the magnetic absorption of big specific surface area and high chemical stability on nano-particle Agent;Third be functional group is connected on magnetic mesoporous nano particle, such as amino, dredge base.
Invention content
In order to overcome the above-mentioned deficiencies of the prior art, it is designed for the absorption of heavy metal ion the present invention provides a kind of The magnetic silica core-shell composite material of amino functional and preparation method thereof with certain adsorption capacity.
A kind of preparation method of magnetic silica core-shell composite material for heavy metal adsorption, includes the following steps:
(1) coprecipitation prepares CoFe2O4Nano particle;
(2)Method is to CoFe obtained by step (1)2O4Nano particle carries out SiO2Cladding, obtains CoFe2O4@SiO2
(3) with gained CoFe2O4@SiO2It is raw material with 3- aminopropyl triethoxysilanes, flow back 4~8h at 60~100 DEG C Obtain black suspension, the CoFe for being dried in vacuo amino modified after separation2O4@SiO2Chain nanocomposite.
Based on it is existing research and there are the problem of, the present invention grasps low cost, high efficiency, free of contamination principle, to magnetism Adsorbent is improved from synthetic method, aspect of performance, has obtained a kind of absorption for heavy metal ion and having for designing The magnetic silica core-shell composite material new solution of the amino functional of certain adsorption capacity.Ferrospinel CoFe2O4For core, this magnetic nano-particle has high coercivity, moderate saturation magnetization, good mechanical strength Equal good characteristics.Unformed SiO2For shell, SiO2Internal magnetic core can be not only protected, also there is the stability of chemistry, it is resistance to Acid is alkaline-resisting.Amino functional magnetic silica core-shell composite material has high adsorption capacity, fast separating rate, selectivity Adsorption function etc..This new solution can need to carry out respective design according to different, this will be to heavy metal containing wastewater treatment side Progradation is played in the research in face, and a guaranteeing role is played to the production and life of people.
The present invention uses the CoFe of improved Co deposited synthesis2O4Magnetic nanoparticle,Method synthesizes SiO2For Shell, CoFe2O4For the CoFe of core2O4@SiO2Chain nanocomposite, then by circumfluence method to its amino functional.SiO2 Shell thickness can adjust on demand, surface also can be grafted corresponding adsorption group according to different adsorption entails.CoFe2O4Magnetism It can be adjusted by sintering condition, and stronger magnetism can be kept, be conducive to the separation of adsorbent.Advantage of the present invention is:System Preparation Method is simple, and manufacturing cost is low.Magnetic nanoparticle and SiO2After compound, still there is higher magnetism, it can be with quick separating. Sorbent structure is stablized, and has chain nucleocapsid.After grafted amino group group, counterweight metal copper ion has certain adsorptivity Energy.This composite modified magnetic adsorbent can be applied to the fields such as radioactive liquid waste processing, the removal of heavy metal ion.
The chain nanocomposite that the present invention is prepared since internal magnetic nanoparticle contact is good, have compared with The high intensity of magnetization, being capable of quick separating.Long-chain longer dimension, stable structure are conducive to its application.
Preferably, CoFe2O4Nano particle is prepared using improved coprecipitation, is included the following steps:
(1) source of iron and cobalt source are dissolved in deionized water according to the ratio, instill NaOH solution dropwise after mixing, obtained reddish brown Polyethylene glycol is added into gained brownish red suspension in color suspension, adjusts pH to 9-12 to obtain dark brown red after mixing suspended Liquid;
(2) gained dark brown red suspension is moved into three-neck flask, flow back 60-90min in boiling water bath, obtains black suspension Liquid, magnet separation take black precipitate, CoFe are obtained after being washed, dried, ground and being sintered successively2O4Nano particle.
It is further preferred that the source of iron is Fe (NO3)3·9H2O, cobalt source is Co (NO3)2·6H2O, source of iron and cobalt source are pressed Molar ratio 1.5~2.5:1 proportioning, wherein source of iron is dissolved in 150mL deionized waters by 0.01~0.03mol and falls into a trap;Most preferably, iron Source and cobalt source in molar ratio 2:1 proportioning, wherein source of iron is dissolved in 150mL deionized waters by 0.02mol and falls into a trap.
It is further preferred that the naoh concentration instilled is 1.0-2.0mol/L, its volume is total according to source of iron and cobalt source Mole adjust, make pH value of solution control within the scope of 10-11.
The addition of PEG and the molar ratio of cobalt source are 2:1.
It is further preferred that the drying is dry 6-12h at 80-90 DEG C in vacuum drying chamber;Most preferably, vacuum is dry Dry 12h at 80 DEG C in dry case.
Further preferably, described be sintered at 300-700 DEG C is sintered 1-7h, most preferably, 1h is sintered at 600 DEG C.
The NaOH solution that pH uses 1.0-2.0mol/L is adjusted in the step.
In the method for the present invention, the magnetic silica microballoon sample of amino functional be by improved coprecipitation,It is prepared by method and boulton process.Ammonium hydroxide (25%) is first used for doing precipitating reagent in coprecipitation process, rear to be used for adjusting solution PH so that iron, cobalt ions form precipitation completely;Polyethylene glycol (PEG 6000) is used as dispersant and template, is to form dispersion Chain structure basis.
Most preferably, 8.08g Fe (NO first3)3·9H2O and Co (NO3)2·6H2O is according to molar ratio 2:1 is dissolved in 150- In 250mL deionized waters, stirred evenly under middling speed;Then the NaOH solution 25-35mL for instilling 1.0-2.0mol/L dropwise, obtains Rufous suspension, then to the PEG that 2.9697g is added in above-mentioned suspension;After stirring evenly, with 1.0-2.0mol/L's NaOH solution adjusts suspension pH, makes it within the scope of 9-12;Obtained uniform dark brown red suspension is transferred to three-neck flask In, make its 60-90min that flows back in boiling water bath;Obtained black precipitate carries out quick separating by magnet, is then carried out to it Fully washing, until neutrality.6-12h is dried in the black precipitate of moistening in vacuum drying chamber at 80-90 DEG C, obtain bright black CoFe2O4Coarse particles, grinding obtain CoFe2O4Presoma powder.Different time (1-7h) and difference finally are carried out to presoma It is sintered at temperature (300-700 DEG C), obtains CoFe2O4Nano particle.
The present invention uses improved coprecipitation, and PEG is added on the basis of original coprecipitation as dispersant and template Agent, on the one hand can improve the dispersibility of nano magnetic particle, these particles is on the other hand made to be strapped in PEG chain structures, Form it into the kernel of chain.It after having adjusted suspension pH, flows back in boiling water bath certain time, keeps reaction more abundant.It is excellent Selection of land, it is describedMethod includes the following steps:
By CoFe2O4In nano particle ultrasonic disperse to ethyl alcohol and the mixed liquor of deionized water, adjusts pH to 10-12 and be added dropwise Ethyl orthosilicate, magnet detaches after being stirred to react 4-48h, and 60-90 DEG C of vacuum drying 6-12h, obtains CoFe after precipitation washing2O4@ SiO2Dark grey powder.
Ethyl alcohol is absolute ethyl alcohol, and the mixed volume ratio of absolute ethyl alcohol and deionized water is 1:1-3:1.
It is further preferred that CoFe2O4The mass volume ratio of nano particle and mixed liquor is 0.5-1.0g:150-250mL.
It is further preferred that CoFe2O4Ultrasonic time of the nano particle in mixed liquor is 30-60min.
PH to 10-12 is adjusted in the step uses ammonium hydroxide (25-28%).
It is further preferred that CoFe2O4(0.5-1.0g) ultrasonic disperse is to alcohol and deionized water 1:1-3:1 mixing In liquid, 15-25mL ammonium hydroxide (25-28%) is added dropwise to adjust pH value of solution in ultrasonic 30-60min, when pH value of solution is 10-12, is added dropwise 5-10mL tetraethyl orthosilicates (TEOS) stir 4-48h with given pace, and Dark grey suspension detaches with magnet, then spend from Sub- water washed several times with water is to neutrality.It is finally 60-90 DEG C of vacuum drying 6-12h in temperature, obtains CoFe2O4@SiO2Dark-grey toner Body.
The present invention existsMethod prepares CoFe2O4@SiO2In the process using vacuum drying, vacuum drying is conducive to keep The chain pattern of composite material.
Preferably, CoFe in step (3)2O4@SiO2Mass volume ratio with 3- aminopropyl triethoxysilanes is (0.5- 1.0)g:(3-6)mL.
Further preferably, first with pure aqueous isopropanol to 0.5-1.0g CoFe2O4@SiO2Fully washing ensures without water ring Then border is dipped into the pure isopropanols of 50-100mL, 3- aminopropyl-triethoxy silicon is added dropwise after 30-60min is stirred at room temperature Alkane (APTES) 3-6mL continues to stir 6h, moves it into three-neck flask, and flow back 6h at 80 DEG C, alcohol washed several times with water, magnet point From last 80-90 DEG C of vacuum drying 6-12h obtains CoFe2O4@SiO2-NH2Black powder.
Solvent is done using pure aqueous isopropanol in the step, preceding 6h is to be stirred at room temperature, and rear 6h is 80 DEG C of return stirrings;Amino The magnetic silica composite material of functionalization has higher saturation magnetization (28.09emu/g), can be at one minute Inside quickly detached by magnet.
The present invention also provides a kind of magnetic silicas for heavy metal adsorption being prepared by the preparation method Core-shell composite material.The magnetic silica composite material that the present invention is prepared has chain nucleocapsid.CoFe2O4Nanometer Particle is core, average grain size 10-15nm;SiO2For shell, average thickness 50nm.The compound that the present invention is prepared Absorption for heavy metal especially copper ion.
The adsorption process of copper ion is as follows:
The Staticadsorption experiment of copper:CoFe is mainly studied using batch process2O4@SiO2-NH2Absorption of the magnetic microsphere to copper Performance, the parameter measured in experiment include mainly this magnetic microsphere to the time of equilibrium adsorption of copper in solution, equilibrium adsorption capacity, Balance removal rate.
Test concrete operation method:In the centrifuge tube of 20 100mL, weigh respectively a certain amount of obtained by step (3) Magnetic composite powder pipettes 50mL copper nitrate standard solution in centrifuge tube, closes the lid, be put into water-bath constant temperature oscillator and shake It swings.Setting the moment respectively take out a centrifuge tube, pipette 10mL supernatants centrifugation, with liquid-transfering gun pipette 1mL supernatants in In 10mL centrifuge tubes, 10-20 times is diluted with deionized water, corresponding absorbance is obtained with atomic absorption spectrography (AAS) and copper ion is dense Degree calculates this sample to the adsorbance of copper, removal rate in solution, draws CoFe2O4@SiO2-NH2Adsorbance, removal rate to copper With the relation curve of adsorption time.
The compound special complexing according to copper ion and amino group prepared by the present invention, we carry out amino to it Functionalization.Different modifications can also be carried out according to the feature of other heavy metal ion.
Each component ratio can be adjusted specifically according to demand in magnetic core-shell complex, also can be directed to different heavy metals from The selective absorption of son carries out material different Modification designs.
Absorption method is widely used, and has the advantages that many uniquenesses for handling heavy metal containing sewage.About adsorbent Research work shows current adsorption technology there are of high cost, and it is relatively low to prepare complicated or adsorption capacity, no adsorptive selectivity etc. Disadvantage.By being grafted adsorption group, reinforces the composite modified of adsorbent, meets different adsorption conditions to improve its adsorption efficiency, Inexpensive there is high-adsorption-capacity and adsorptive selectivity and prepare simple magnetic adsorbent is prepared to be of great significance.
The chain core-shell nano magnetism of the amino functional of adsorption design provided by the invention for heavy metal ion is multiple The new solution of condensation material.The magnetic silica nanocomposite of amino functional be by improved coprecipitation,It is prepared by method and boulton process.SiO2Shell thickness can adjust on demand, surface can also connect according to different adsorption entails The corresponding adsorption group of branch.CoFe2O4Magnetism can be adjusted by sintering condition, and stronger magnetism can be kept, be conducive to The separation of adsorbent.This material we illustrates phase in the formation mechenism and material of each process to the adsorption mechanism of copper ion The explanation and theoretical foundation answered.This technical solution technique and easy to operate, it is environmental-friendly, different heavy metals can be directed to and carried out Different designs.Such material may be used on the processing of heavy metal containing sewage and radioactive wastewater.
Description of the drawings
Fig. 1 is the flow chart of preparation method of the present invention.
Fig. 2 is three kinds of product (CoFe in preparation process2O4NPs、CoFe2O4@SiO2And CoFe2O4@SiO2-NH2) formation Mechanism figure.
Fig. 3 is CoFe2O4NPs、CoFe2O4@SiO2And CoFe2O4@SiO2-NH2XRD diagram (a) and FTIR scheme (b).
Fig. 4 is CoFe2O4NPs、CoFe2O4@SiO2And CoFe2O4@SiO2-NH2SEM schemes and corresponding TEM figures.
Fig. 5 is CoFe2O4NPs、CoFe2O4@SiO2And CoFe2O4@SiO2-NH2Magnetization curve figure (a) at room temperature and magnetic Field separating effect figure (b).
Fig. 6 is the CoFe for not adding PEG (6000) (a) and addition PEG (6000) (b) to obtain2O4NPs pattern comparison diagrams.
Fig. 7 is the CoFe under different sintering temperatures2O4The XRD diagram (a) of NPs and corresponding magnetization curve figure at room temperature (b)。
Fig. 8 is the magnetic silica nanocomposite (CoFe of amino functional2O4@SiO2-NH2) copper ion is inhaled It is attached about adsorbance (b), the relation curve of removal rate (a) and adsorption time.
Specific implementation mode
With reference to specific embodiments and the drawings, the present invention is further illustrated.
Embodiment 1
Technological process is as shown in Figure 1.
Step 1:CoFe is prepared using improved coprecipitation2O4Nano magnetic particle
By Fe (NO3)3·9H2O and Co (NO3)2·6H2O is according to molar ratio 2:1 (wherein Fe (NO3)3·9H2O is It 0.02mol) is dissolved in 150mL deionized waters, is stirred evenly under middling speed.Then the NaOH solution of 2.0mol/L is instilled dropwise 25mL obtains rufous suspension, then to addition 0.02mol PEG 6,000 in above-mentioned suspension.After stirring evenly, use The NaOH solution of 2.0mol/L adjusts suspension PH, makes it within the scope of 10-11.Obtained uniform dark brown red suspension transfer Into three-neck flask, make its 90min that flows back in boiling water bath.Obtained black precipitate carries out quick separating by magnet, then It is fully washed, until neutrality.12h is dried in the black precipitate of moistening in vacuum drying chamber at 80 DEG C, obtain brilliant black Color CoFe2O4Coarse particles, grinding obtain CoFe2O4Presoma powder.1h finally is sintered to presoma at 600 DEG C, is put down The CoFe that equal size is 10-15nm2O4Nano particle.
Step 2:CoFe2O4@SiO2The synthesis of magnetic nanometer composite material
The CoFe that step 1 obtains2O4Nano particle is distributed in alcohol and the mixed solution of deionized water, when one section ultrasonic Between after suitable ammonium hydroxide (25%) is added dropwise to adjust solution PH, when solution PH is 10.5-11, tetraethyl orthosilicate is added dropwise (TEOS), 48h is stirred with given pace, Dark grey suspension detaches with magnet, then with deionized water washed several times with water to neutrality.Most It is afterwards 80 DEG C of dry 12h in true temp, obtains CoFe2O4@SiO2Dark grey powder.
Step 3:Amino modified CoFe2O4@SiO2The synthesis of magnetic nanometer composite material
The CoFe that first step 2 is obtained with pure aqueous isopropanol2O4@SiO2Fully washing ensures water-less environment, then will It is dipped into the pure isopropanols of 50mL, and the 3- aminopropyl triethoxysilanes of dropwise addition 3mL after a period of time are stirred at room temperature (APTES), continue to stir 6h, move it into three-neck flask, flow back 6h at 80 DEG C, alcohol washed several times with water, and magnet separation, 80 DEG C true The dry 12h of sky obtains CoFe2O4@SiO2-NH2Black powder.
The experiment flow figure of the obtained products of above-mentioned steps 1-3 and formation mechenism is as depicted in figs. 1 and 2.The phase of product Structure and molecular structure are tested to obtain by XRD and FTIR respectively, as shown in (a) and (b) in Fig. 3, wherein (a) is XRD diagram, (b) it is that FTIR schemes.From XRD spectrum, we, which can obtain, has formd CoFe2O4Spinel structure, and occur after coating SiO2Amorphous peak.The results of FT-IR shows the vibration of the absorption peak there are Si-O-Si, and the vibration of-NH, on the one hand says Clear silica successfully coats, and on the other hand illustrates the success of amino functional.
Product is placed under scanning electron microscope and observes its surface topography, its fine structure is observed under transmission electron microscope, such as Fig. 4 institutes Show.(a) is CoFe in Fig. 42O4The SEM of NPs schemes, and is (d) CoFe2O4The TEM of NPs schemes, and (a) and (d) can be seen that in Fig. 4 CoFe2O4Magnetic nanoparticle is evenly distributed, average diameter 10-15nm;SiO2The chain with nucleocapsid is formed after cladding Pattern, coating thickness are about 50nm, and in Fig. 4 shown in (b) and (e), (b) is CoFe in Fig. 42O4@SiO2SEM figure, (e) it is CoFe2O4@SiO2TEM figure;Pattern and fine structure all do not change after amino modified, in Fig. 4 (c) and (f) Shown, (c) is CoFe in Fig. 42O4@SiO2-NH2SEM figure, (f) be CoFe2O4@SiO2-NH2SEM figure.(a) is provided in Fig. 5 CoFe2O4、CoFe2O4@SiO2And CoFe2O4@SiO2-NH2Magnetization curve figure, their saturation magnetization is respectively 61.96、31.41、23.84emu/g.Continuously decreasing for the intensity of magnetization is the increase because of namagnetic substance, but CoFe2O4@ SiO2-NH2Also it is easy to be detached by magnet in one minute, in Fig. 5 shown in (b).
In addition step 1 does not add PEG (6000) and the CoFe that PEG (6000) is formed is added2O4Magnetic-particle pattern comparison diagram point Not as shown in (a) and (b) in Fig. 6.Not plus the reunion of the magnetic-particle of PEG (6000) is more serious, and dispersibility is preferable after addition, and Just there is certain chainlike distribution.
Step 1 to magnetic-particle be sintered under certain temperature, and the XRD diagram of the magnetic-particle obtained under different temperatures is as schemed In 7 shown in (a), accordingly in magnetization curve figure such as Fig. 7 at room temperature shown in (b).Increase with the raising crystallinity of sintering temperature Add, particle size becomes larger, saturation magnetization enhancing.
Embodiment 2
Step 2 and 3 obtained products carry out Staticadsorption experiment to Cu (II) ion in embodiment 1.
In the centrifuge tube for taking 20 100mL respectively, the quality that adsorbent is added in each volumetric flask is identical, pipettes The copper nitrate standard solution that 50mL is prepared is put into water-bath constant temperature oscillator and vibrates in ionic tube.It is respectively taken out at the setting moment One centrifuge tube, pipette 10mL supernatants centrifugation, pipette 1mL supernatants in 10mL centrifuge tubes with liquid-transfering gun, spend from Sub- water dilutes 10 times, obtains corresponding absorbance and copper ion concentration with atomic absorption spectrography (AAS), calculates this sample in solution The adsorbance of copper, removal rate, draw adsorbance, removal rate and adsorption time relation curve.
It is illustrated in figure 8 the magnetic silica composite material (CoFe of amino functional2O4@SiO2-NH2) to copper ion The relation curve about adsorbance, removal rate and adsorption time of absorption, the pH of solution are fixed as 5.(a) it is removal rate and absorption The relation curve of time is (b) relation curve of adsorbance and adsorption time.Time started, the rate of adsorption quickly, when absorption when Between be 200min when, absorption become slow, basically reach saturation.Here the magnetic silica before not providing functionalization is compound (the CoFe of material2O4@SiO2) adsorption curve, be because in 400min CoFe2O4@SiO2To copper ion substantially without absorption. This illustrates-the NH of the rear surface of amino functional2There is special complexing to copper ion.This result also illustrates CoFe2O4@ SiO2-NH2Selective absorption function.

Claims (2)

1. a kind of preparation method of magnetic silica core-shell composite material for heavy metal adsorption, which is characterized in that including Following steps:
(1) coprecipitation prepares CoFe2O4Nano particle;
Coprecipitation includes the following steps:
(a) source of iron and cobalt source are dissolved according to the ratio in deionized water, instill NaOH solution dropwise after mixing, it is outstanding to obtain rufous Polyethylene glycol is added into gained rufous suspension in supernatant liquid, adjusts pH to 9-12 to obtain dark brown red suspension after mixing;
(b) gained dark brown red suspension being moved into three-neck flask, flow back 60-90min in boiling water bath, obtains black suspension, Magnet separation takes black precipitate, and CoFe is obtained after being washed, dried, ground and being sintered successively2O4Nano particle;The source of iron is Fe(NO3)3·9H2O, cobalt source is Co (NO3)2·6H2O, source of iron and cobalt source in molar ratio 1.5~2.5:1 proportioning, wherein source of iron with 0.01~0.03moL is dissolved in 150mL deionized waters and falls into a trap;The naoh concentration of instillation be 1.0-2.0mol/L, dosage so that The pH of solution is counted within the scope of 10-11;The drying is dry 6-12h at 80-90 DEG C in vacuum drying chamber;It is described to be sintered to It is sintered 1-7h at 300-700 DEG C;
(2)Method is to CoFe obtained by step (1)2O4Nano particle carries out SiO2Cladding, obtains CoFe2O4@SiO2
Method includes the following steps:
By CoFe2O4In nano particle ultrasonic disperse to ethyl alcohol and the mixed liquor of deionized water, it is added dropwise just after adjusting pH to 10-12 Silester, magnet detaches after being stirred to react 4-48h, and 60-90 DEG C of vacuum drying 6-12h, obtains CoFe after precipitation washing2O4@ SiO2Powder;CoFe2O4The mass volume ratio of nano particle and mixed liquor is 0.5-1.0g:150-250mL;
(3) with gained CoFe2O4@SiO2It is raw material with 3- aminopropyl triethoxysilanes, the 4~8h that flows back at 60~100 DEG C is obtained Black suspension, the CoFe for being dried in vacuo amino modified after separation2O4@SiO2Chain core-shell nano composite material;Step (3) Middle CoFe2O4@SiO2Mass volume ratio with 3- aminopropyl triethoxysilanes is (0.5-1.0) g:(3-6)mL.
2. the magnetic silica nucleocapsid for heavy metal adsorption that a kind of preparation method as described in claim 1 is prepared is multiple Condensation material.
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