CN106466605A - A kind of Fe3O4@SiO2The preparation method of@ZnO magnetic nanometer photocatalyst - Google Patents
A kind of Fe3O4@SiO2The preparation method of@ZnO magnetic nanometer photocatalyst Download PDFInfo
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- CN106466605A CN106466605A CN201610628500.9A CN201610628500A CN106466605A CN 106466605 A CN106466605 A CN 106466605A CN 201610628500 A CN201610628500 A CN 201610628500A CN 106466605 A CN106466605 A CN 106466605A
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- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 title claims abstract description 315
- 239000011941 photocatalyst Substances 0.000 title claims abstract description 42
- 238000002360 preparation method Methods 0.000 title claims abstract description 29
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 161
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- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims description 8
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- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 description 2
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- ZSDSQXJSNMTJDA-UHFFFAOYSA-N trifluralin Chemical compound CCCN(CCC)C1=C([N+]([O-])=O)C=C(C(F)(F)F)C=C1[N+]([O-])=O ZSDSQXJSNMTJDA-UHFFFAOYSA-N 0.000 description 1
- HRXKRNGNAMMEHJ-UHFFFAOYSA-K trisodium citrate Chemical class [Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O HRXKRNGNAMMEHJ-UHFFFAOYSA-K 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/80—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with zinc, cadmium or mercury
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/33—Electric or magnetic properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/39—Photocatalytic properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
- B01J37/0063—Granulating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
- B01J37/341—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
- B01J37/344—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of electromagnetic wave energy
- B01J37/346—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of electromagnetic wave energy of microwave energy
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Health & Medical Sciences (AREA)
- Plasma & Fusion (AREA)
- Toxicology (AREA)
- Catalysts (AREA)
Abstract
A kind of Fe3O4@SiO2The preparation method of@ZnO magnetic nanometer photocatalyst, comprises the steps：(1) weigh 2.24g Zn (CH3COO)2·2H2O is added in a 100mL DEG solution, and ultrasonic wave added dissolves, and microwave heating obtains the first intermediate reaction liquid；(2) weigh 0.2g Fe3O4@SiO2It is added in another 20mL DEG solution, ultrasonic wave added dissolves, microwave heating obtains the second intermediate reaction liquid；(3) the first intermediate reaction liquid and the second intermediate reaction liquid are mixed, microwave heating obtains mixed reaction solution；(4) it is cooled to room temperature, centrifugation, cleaning, obtain final product after being dried.Compared with existing photocatalyst, the inventive method gained Fe3O4@SiO2The photocatalytic activity of@ZnO is higher, and more preferably, the scope of application is wider for stability, and good Magneto separate performance is also beneficial to reduce secondary pollution.
Description
Technical field
The present invention relates to field of catalyst preparation, specifically a kind of Fe3O4@SiO2The system of@ZnO magnetic nanometer photocatalyst
Preparation Method.
Background technology
Photocatalyst is exactly to play catalytic degradation effect under the exciting of photon, accelerates or to slow down photochemistry anti-
Should, but itself is not involved in the general designation of the chemical substance of reaction again.Under the conditions of under room temperature, electric conductivity between conductor and insulator it
Between material be referred to as semi-conducting material.The semi-conducting material possessing certain photocatalytic degradation capability is referred to as conductor photocatalysis
Agent.The simple synthetic method of magnetic ZnO, quick, and have that environment-protecting asepsis, low cost, stability is high, photocatalytic activity by force with
And easily the features such as recycle, can effectively remove the organic pollution of difficult for biological degradation in eliminating water, be more satisfactory photocatalysis material
Material.But current synthetic method haves such problems as that power consumption, time-consuming, dispersant or raw material are poisonous, and the material settling out synthesizing
Property is poor, photocatalytic activity is low and solid-liquid separation effect is poor, is current problem demanding prompt solution.Research worker is to magnetic both at home and abroad
Rest on the degraded dye liquor stage more the exploration of ZnO, process the research of paranitrophenol waste water of difficult for biological degradation and document rarely has
Report is it would be highly desirable to further study and application.
Content of the invention
For effectively solving the problems referred to above, the present invention is with Fe3O4For magnetic core, coated Si O2Protective layer, ZnO is as multi-functional outer
Shell, using the method synthesis Fe of Microwave-assisted firing, diglycol (DEG) auxiliary agent adding asepsis environment-protecting3O4@SiO2@
ZnO magnetic nanometer photocatalyst.
To achieve these goals, present invention employs technical scheme below：
A kind of Fe3O4@SiO2The preparation method of@ZnO magnetic nanometer photocatalyst, comprises the steps：
(1) it is Zn (CH according to w/v3COO)2·2H2O:DEG=2.0～2.5g:90～110mL mixes, and surpasses
Sound aid dispersion 10～12min, then in microwave power be 550～650W, temperature be 145～155 DEG C under conditions of heating 5～
8min, obtains the first intermediate reaction liquid；
(2) it is Fe according to w/v3O4@SiO2:DEG=0.15～0.25g:15～20mL mixes, and ultrasonic wave added
Dispersion 10～12min, then in microwave power be 550～650W, temperature be 145～155 DEG C under conditions of heat 5～8min,
Obtain the second intermediate reaction liquid；
(3) according to volume parts meter, 90～110 part of first intermediate reaction liquid and 15～25 part of second intermediate reaction liquid are mixed
Close, then microwave power be 550～650W, temperature be 155～165 DEG C under conditions of heat 15～20min, obtain mixing anti-
Answer liquid；
(4) reactant liquor to be mixed is cooled to room temperature, centrifugation, washes the DEG solution of solid residue, vacuum drying
Afterwards, obtain Fe3O4@SiO2@ZnO magnetic nanometer photocatalyst, is stored in drying tower.
Described Fe3O4@SiO2It is prepared by the following method：
(1) according to volume parts meter, the ammonia that 1 part of mass fraction is 25% is mixed with 1.8～2.2 parts of dehydrated alcohol,
It is configured to ammonia-ethanol solution；
(2) according to volume parts meter, 1 part of tetraethyl orthosilicate is mixed with 8～12 parts of dehydrated alcohol, be configured to positive silicic acid second
Ester-ethanol solution；
(3) first count by weight, by 0.8～1.2 part of Fe3O4It is mixed to get first with 0.8～1.2 part of sodium citrate to mix
Compound material, adds the ratio of 240～260mL dehydrated alcohol and 240～260mL deionized water according still further to every gram of first mixed material
Add dehydrated alcohol and deionized water, ultrasonic disperse 10～12min in the first mixed material, obtain Fe3O4Disperse system；
(4) first according to volume parts meter, measure respectively 13～17 parts of ammonia-ethanol solution, 10～12 parts of tetraethyl orthosilicates-
Ethanol solution and 220～280 parts of Fe3O4Disperse system, then by tetraethyl orthosilicate-ethanol solution and ammonia-ethanol solution simultaneously by
Gradually instill Fe3O4Disperse system, in course of reaction, makes temperature of reaction system maintain 68～72 DEG C by Microwave-assisted firing, and carries out
Lasting mechanical agitation, the response time is 20～30min；
(5) products therefrom is centrifuged, washing, after vacuum drying, obtains Fe3O4@SiO2, it is stored in drying tower.
Described Fe3O4It is prepared by the following method：
(1) count by weight, by 120～150 parts of FeCl3·6H2O, 340～380 parts of CH3COONa and 10～20 part
Sodium citrate mix homogeneously obtains the second mixed material, adds 8～10 milliliters of ethylene glycol according still further to every gram of second mixed material
Bulking value ratio adds ethylene glycol in the second mixed material, is uniformly mixing to obtain mixed liquor；
(2) mixed liquor is transferred in politef hydrothermal reaction kettle, makes reactor be 190～210 DEG C in temperature
Heat 8～10h in Muffle furnace, be then centrifuged for separating, washing, be dried, obtain monodispersed Fe3O4Nano material.
Compared with prior art, the beneficial effect that the present invention possesses：
With TiO2Compare, the inventive method gained Fe3O4@SiO2The photocatalytic activity of@ZnO is higher, and stability more preferably, is fitted
Wider with scope, good Magneto separate performance is also beneficial to reduces cost and reduces the harm that secondary pollution brings.8 times continuous
Recycling experiment does not make degradation rate occur significantly declining, and the degradation rate in the 8th cycle is still up to 82.3%；Urge
Not there is significant change in the XRD diffracting spectrum before and after change, show Fe3O4@SiO2The stability of@ZnO is high.The present invention not only may be used
Synthesis for ZnO and similar semiconductors coupling catalysis material provides new method and thinking, also helps thorough elimination ring
Larger paranitrophenol pollutant are endangered, the exploration of the present invention is to other quick green syt catalysis materials and light in border
Catalytic degradation poisonous and hazardous petroleum phenol pollutant also have important reference value.The diglycol that the present invention uses
(DEG) it is to be obtained by oxirane and ethylene glycol, substantial amounts of hydroxyl can be decomposited at a certain temperature, promote to produce between ion
Give birth to sterically hindered and ion can not be combined with each other, this can reduce the particle diameter of nano material, can stop nano material again
Reunite.In addition, the boiling point of the specific heat capacity of 2.31kJ/ (kg K) and 245 DEG C, illustrate that it is a kind of microwave heat transfer property
Excellent solvent.
Brief description
Fig. 1 is Fe3O4@SiO2The preparation flow schematic diagram of@ZnO.
Fig. 2 is different plus the Fe of quantity of magnetism preparation3O4@SiO2The photocatalysis efficiency of@ZnO.
Fig. 3 is different plus the quantity of magnetism XRD spectrum：(a)0.05g·g-1, (b) 0.2g g-1, (c) 0.3g g-1.
Fig. 4 is different plus the quantity of magnetism hysteresis curve：(a)0.3g·g-1, (b) 0.2g g-1, (c) 0.05g g-1.
Fig. 5 is the FESEM shape appearance figure of microwave heating time：A, d (15min), b, e (30min), c, f (60min).
Fig. 6 is the Fe of different microwave heating time preparations3O4@SiO2The photocatalysis efficiency of@ZnO.
Fig. 7 is FESEM shape appearance figure:(a)Fe3O4；(b)Fe3O4@SiO2；(c)ZnO；(d-f)Fe3O4@SiO2@ZnO.
Fig. 8 is XRD spectrum：(a)Fe3O4@SiO2, (b) Fe3O4.
Fig. 9 is XRD spectrum：(a) ZnO, (b) Fe3O4, (c) Fe3O4@SiO2@ZnO.
Figure 10 is FT-IR spectrum：(a)Fe3O4@SiO2, (b) Fe3O4.
Figure 11 is FT-IR spectrum：(a) ZnO, (b) Fe3O4, (c) Fe3O4@SiO2@ZnO.
Figure 12 is DRS absorption spectrum and (Ahv)2- hv curve：(a)Fe3O4, (b) ZnO, (c) Fe3O4@SiO2@ZnO.
Figure 13 is the contrast of hysteresis curve：(a)Fe3O4, (b) Fe3O4@SiO2, (c) Fe3O4@SiO2@ZnO.
Figure 14 is the impact to photocatalytic degradation efficiency for the light source.
Figure 15 is the impact to photocatalytic degradation efficiency for the catalyst amountses.
Figure 16 is the impact to photocatalytic degradation efficiency for the paranitrophenol initial concentration.
Figure 17 is the impact to adsorption efficiency for the paranitrophenol initial concentration.
Figure 18 is the paranitrophenol salinity of different light application times.
Figure 19 is the absorption spectrum change of paranitrophenol.
Figure 20 is the maximum absorption wavelength change curve under different pH.
Figure 21 is the impact to adsorption efficiency for the paranitrophenol original ph.
Figure 22 is the impact to photocatalysis efficiency for the paranitrophenol original ph.
The impact to photocatalysis efficiency for the concentration for HA for the Figure 23.
Figure 24 is the photocatalytic degradation efficiency change curve continuously recycling for 8 times.
Figure 25 is the XRD spectrum before and after photocatalytic degradation：Before (a) catalysis, after (b) catalysis.
Figure 26 is zero order reaction kinetics matching.
Figure 27 is pseudo-first order reaction kinetics matching.
Figure 28 is ZnO photocatalysis oxidation reaction mechanism figure under ultraviolet light.
Figure 29 is Fe3+Improve the mechanism of photocatalysis performance.
Figure 30 is the different degradation pathway schematic diagrams of paranitrophenol.
Specific embodiment
Below by embodiment, technical scheme is further elaborated.
Embodiment 1
Chapter 1, preparation method
A kind of Fe3O4@SiO2The preparation method of@ZnO magnetic nanometer photocatalyst, comprises the steps：
(1) weigh 2.24g Zn (CH3COO)2·2H2O is added in a 100mL DEG solution, and carries out ultrasonic wave added
Dissolving 10min, then in microwave power be 600W, temperature be 150 DEG C under conditions of heat 5min, obtain the first intermediate reaction
Liquid；
(2) weigh 0.2g Fe3O4@SiO2It is added in another 20mL DEG solution, and carry out ultrasonic wave added dissolving
10min, then in microwave power be 600W, temperature be 150 DEG C under conditions of heat 5min, obtain the second intermediate reaction liquid；
(3) the first intermediate reaction liquid and the second intermediate reaction liquid are mixed, then microwave power be 600W, temperature be
Heat 15min under conditions of 160 DEG C, obtain mixed reaction solution；
(4) reactant liquor to be mixed is cooled to room temperature, cleans the DEG of residual after centrifugation with ethanol in proper amount and deionized water
Solution, obtains Fe after vacuum drying3O4@SiO2@ZnO magnetic nanometer photocatalyst, is stored in drying tower, for suction afterwards
Attached experiment and photocatalytic degradation experiment.
Described Fe3O4@SiO2It is prepared by the following method：
(1) ammonia that 5mL mass fraction is 25% is joined with 10ml dehydrated alcohol and be mixed and made into ammonia-ethanol solution；
(2) 1mL tetraethyl orthosilicate and 10ml dehydrated alcohol are hybridly prepared into tetraethyl orthosilicate-ethanol solution；
(3) weigh 0.2g Fe3O4Be placed in beaker with 0.2g sodium citrate, add 100mL dehydrated alcohol and 100mL go from
Sub- water, ultrasonic disperse 10min, Microwave-assisted firing makes temperature of reaction system maintain 70 DEG C, by tetraethyl orthosilicate-ethanol solution
It is gradually dropped with ammonia-ethanol solution, course of reaction carries out lasting mechanical agitation, the response time is 30min simultaneously；
(4) products therefrom carries out the heart and separates, and some times of deionized water, washing with alcohol, after vacuum drying 3h, collects
End-product Fe3O4@SiO2In drying tower, so that follow-up preparation uses.
Described Fe3O4It is prepared by the following method：
(1) precise 1.35g FeCl3·6H2O、3.6g CH3COONa and 0.15g sodium citrate, adds 40mL second
Glycol, obtains mixed liquor；
(2) after mixed liquor high-speed stirred 1h, will move in the politef hydrothermal reaction kettle that capacity is 50mL, make reaction
Kettle 200 DEG C of work 8h in Muffle furnace, are then centrifuged for separating, and after repeatedly washing through ethanol and deionized water, are placed in 70 DEG C of vacuum
Drying baker is dried, and obtains monodispersed Fe3O4Nano material, the sample after dried is placed in drying tower, so that subsequently real
Test use.
Synthesis Fe3O4@SiO2The flow process of@ZnO magnetic nanometer photocatalyst is as shown in Figure 1.
Chapter 2, Fe3O4@SiO2The performance study of@ZnO
2.1 experimental raw and characterizing method
2.1.1 experiment reagent
The used chemical agent of this chapter test and its corresponding molecular formula, technical specification and production firm are listed in table 1 in detail.
Table 1 main chemical and technical specification
2.1.2 experimental apparatus
The used key instrument of this chapter test is listed in Table 2 below in detail.
Table 2 experimental apparatus
2.1.3 material characterization method
The N of sample2Adsorption and desorption isotherms measurement adopts Tristar II3020 adsorption instrument, and before test, sample is in vacuum bar
The lower 100 DEG C of degassings in advance of part are no less than 6h.BET specific surface area passes through the Brunauer-Emmett-Teller (BET) method
It is calculated.Pore volume (Vt) and aperture (D) adopt The Barrett-Joyner-Halenda (BJH) by isothermal line desorption branch
Model calculates gained, its mesopore volume relative pressure p/p0Adsorbance at=0.99 is calculated.
The INSTRUMENT MODEL that Electronic Speculum characterizes is SU-8020 field emission scanning electron microscope (FESEM), for observing gained material
The pattern of material.Running voltage is 10.0kV, about 50～100K times of amplification.Sample powder is scattered in ethanol first, mixing
Ultrasonic 10min, then mixed liquor is dropped in copper duplex contained network, subsequently contained network is placed on square aluminum slice, uses after air-drying
Aluminium flake is fixed on microscope carrier conducting resinl, finally moves into vacuum chamber and is imaged.
X-ray diffraction (XRD), is approximated the atomic distance of crystal by the wavelength of X-ray, when leading to X-ray transparent crystal
Diffraction can occur.The X-ray diffractometer that experiment uses comes from the D/max 2500V that Japanese Shimadzu Corporation produces, for true
The crystal formation of random sample product, crystalline phase, purity and density etc..Running voltage 40kV of instrument, accelerates electric current 20mA, and Cu/K α is ray
Source λ=0.15406nm, scanning angle 2 θ=10～80 ° and sweep speed are 5 °/min.
Fourier infrared spectrum (FTIR) is mainly by the infrared absorption characteristic of sample come its chemical analysis of identification and analysis
With molecular structure.Test gained infared spectrum is contrasted with standard comparison card or standard scan collection of illustrative plates, is drawn by similarity
The species of compound, the intensity according to absworption peak and half-peak breadth measure constituent content.Produced using U.S. Nicolet
Nicolet Nexus 470 is tested, and makes transparent sheet with KBr pressed disc method, and measurement wave-number range is 4000～400cm-1.
UV-vis DRS spectrum (UV-vis DRS) is a kind of main of evaluation catalyst absorbing properties quality
Means.Due to gap shifts, semi-conducting material corresponding UV-vis DRS absorption spectrum is led to change, then by curve
Variation tendency calculates the optical absorption characteristics of semi-conducting material.Divided using the UV-3600 type ultraviolet-visible that Japanese Shimadzu Corporation produces
Light photometer is tested.With BaSO4As reference, sweep speed is 0.6nm s-1, absorption value sweep limitss be 300～
800nm.Following two formula are mainly applied to calculate the energy gap of material and corresponding light absorption wavelength：
Wherein h, v,λ, A and Eg represent planck constant (J S) respectively, frequency of light wave (Hz), absorbance (a.u.),
Light absorption wavelength (nm), absorptance constant and energy gap (eV),
Vibrating specimen magnetometer (VSM) is the equipment testing magnetic material performance on the basis of electromagnetic induction.The present invention
Measured using 7410 types VSM of Lake shore company of the U.S. and include：The indexs such as saturation magnetic intensity, coercivity and residual magnetization.
At room temperature, external magnetic field sweep limitss are ± 20KOersted, and step rate is 6Oe s-1.
2.2 preparation factors are investigated
The difference of preparation condition can directly influence pattern, structure and the performance of composite, in order to synthesize small size, height
Performance, the Fe of nucleocapsid structure3O4@SiO2@ZnO magnetic composite, need to optimize preparation condition.The present invention uses the method for fractional steps
Preparation Fe3O4@SiO2@ZnO magnetic nanometer composite material, involved controllable parameter is more, in reference literature and seminar forefathers
On the basis of experience, 2 crucial preparation influence factors are mainly investigated：Plus the quantity of magnetism and microwave heating time.
(1) add the impact of the quantity of magnetism
On the basis of 2.2.1, Fe is set3O4@SiO2Quality be 0～0.30g scope level point at equal intervals, other systems
Standby factor all keeps constant, by material characterization and photocatalytic degradation experiment, investigate plus the quantity of magnetism to the size of material, pattern and
The impact of photocatalytic activity.
(2) impact of microwave heating time
To synthesize Fe in 2.2.13O4@SiO2The method of@ZnO magnetic nanometer composite material and plus the quantity of magnetism be optimized for base
Plinth, the different microwave heating time of setting three, respectively 15,30,60min, other factorses remain unchanged, and are tested by photocatalysis
And the sign of material, inquire into the impact of different sizes, pattern and photocatalytic activity to product for the microwave heating time.
2.3 photocatalytic activity evaluation
Paranitrophenol microgranule 0.200g after precise drying, dissolves constant volume in dislocation 1L volumetric flask, makes
200mg·L-1Storing solution standby.The dilution that this experiment variable concentrations p-nitrophenyl phenol solution used is all from storing solution is joined
System.Solution used by this chapter does not all adjust original ph.
The present invention adopts BL-GHX-V type photochemical reaction instrument Solar Photocatalytic Degradation of P-nitrophenol waste water, using 300W high pressure
Mercury lamp is as light source.Experimental technique is：By a certain amount of catalyst and 25mL 30mg L-1Paranitrophenol add quartz anti-
Answer in device, after the ultrasonic 10min in dark place, to reach adsorption equilibrium, light application time is 120min to stirring 30min.Catalytic kinetic class hour,
Light application time is adjusted to 180min, takes 5mL sample liquid centrifugation at set intervals, is placed in UV-2550 UV-vis spectroscopy light
In degree meter, with deionized water as reference, measure the extinction value changes in its maximum absorption wave strong point for the paranitrophenol, calculate degraded
Rate DR (%).
Wherein, C0、CtThe instantaneous concentration of the concentration of paranitrophenol and t after illumination when being respectively dark adsorption equilibrium.
2.4 results and discussion
Efficiently and conveniently synthesize Fe using microwave-assisted-solvent-thermal method3O4@SiO2@ZnO magnetic nanometer photocatalyst, needs
Rung by size, pattern, crystal formation, chemical analysis, molecular structure and magnetic that different characterizing methods further appreciates that products therefrom
Feature should be waited.
2.4.1 plus the quantity of magnetism impact
The size in specific surface area and pore volume aperture directly affects material absorption, catalytic performance.General specific surface area and pore volume
Aperture is bigger, and the absorbability of material is stronger, and entrained catalysis activity point position is more, and the utilization rate of photon is higher, photocatalysis
Degradation capability is also stronger.Table 3 is shown as the different specific surface areas adding quantity of magnetism synthetic material, pore volume aperture.Can from table
Go out, 0.2g g-1Plus the material specific surface area of the quantity of magnetism and pore volume aperture are maximum, its specific surface area is than 0.3g g-1Plus the quantity of magnetism
Sample will have more 1/3, and pore volume is 0.05g g-1Plus 3 times of quantity of magnetism material, aperture is 2 times.
The different Fe adding quantity of magnetism preparation of table 33O4@SiO2The N of@ZnO2- BET parameter
Fig. 2 is the Fe of synthesis under the conditions of difference plus the quantity of magnetism3O4@SiO2@ZnO magnetic composite photocatalytic degradation is to nitro
The degradation rate of phenol-time effects curve.It can be seen that as addition Fe3O4@SiO2Quality be 0 when, p-nitrophenyl
The degradation rate of phenol is only 78.9%, is that 7 serial level points are minimum.With adding being gradually increased of the quantity of magnetism, photocatalytic activity is also steady
Step rises, as addition Fe3O4@SiO2Quality be 0.3g when, in solution, 93.8% paranitrophenol molecule is degraded.Degraded
Rate is with Fe3O4@SiO2The increase of quality and rising is because that photon excitation valence-band electrons migrate to conduction band, has and is catalyzed by force
Photoelectron-the hole pair of oxidability, but its life-span is extremely short, is susceptible to be combined, inertia Fe3O4@SiO2For photoelectron-hole
More attachment point positions are provided, effectively reduce it and compound probability occurs, so that the efficiency of catalytic degradation paranitrophenol improves.
From in figure it is found that adding the quantity of magnetism is 0.2,0.25 and 0.3g g-1When, final degradation rate is respectively 93.8,90.6 and
88.9%, that is, the photocatalytic activity of three be more or less the same.
Fig. 3 is the X ray diffracting spectrum that three kinds of differences add the quantity of magnetism, a, b, c of in figure represent respectively plus the quantity of magnetism be 0.05,
0.2、0.3g·g-1.It can be seen that being 0.05g g when adding the quantity of magnetism-1When, the feature that ZnO only in composite is spread out
Penetrate peak；Fe in composite3O4The intensity of characteristic diffraction peak strengthens with the increase adding the quantity of magnetism, and material tends to show
Fe3O4Feature.
Fig. 4 is the hysteresis curve collection of illustrative plates that three kinds of differences add the quantity of magnetism, a, b, c of in figure represent respectively plus the quantity of magnetism be 0.3,0.2,
0.05g·g-1.The maximum of hysteresis curve be material saturation magnetic intensity, its as the important indicator of material magnetic response ability,
The value of general saturation magnetic intensity is bigger, and the magnetic of material is stronger.The saturation magnetic intensity of a and b material will be apparently higher than a, explanation
0.2、0.3g·g-1Plus the magnetism of material of quantity of magnetism synthesis is better than 0.05g g-1.Contrast 0.2 and 0.3g g-1Two kinds plus the quantity of magnetism,
Find 0.3g g-1Plus the linear of the material hysteresis loop line of quantity of magnetism synthesis is not so good as 0.2g g-1, there are certain hysteresis.
And 0.2g g-1Plus the final material of quantity of magnetism synthesis then has superparamagnetism, when there is externally-applied magnetic field, material can be directed receipts
, there are not hysteresis in collection.Consider photocatalytic activity, magnetic response ability, active ingredient and the cost of magnetic composite,
0.2g·g-1Plus the quantity of magnetism be optimal.
2.4.2 the impact of microwave heating time
Compare traditional heating mode, the method for Microwave-assisted firing has efficient, safety, heats up uniformly, reduces reaction and lives
Change the advantages such as energy.In addition, when microwave-assisted prepares material, it can also carry out the other stirring of molecular level to reaction system, makes
More preferably, smaller, pattern is more regular for the dispersibility of material, reduces the agglomeration of nano material and traditional heating mode is made
The drawbacks of hot-spot becoming.Microwave-assisted can greatly shorten the cycle of material preparation, can efficiently control cost and material
The characteristic of material.Therefore, for reduces cost, shorten the cycle, synthesis size, pattern, the material of excellent performance, inquire into different microwaves
The impact to synthetic material performance for the time of auxiliary heating is particularly important.
A, b, c in Fig. 5 represent respectively the microwave-assisted time be 15,30,60min synthesis Fe3O4@SiO2@ZnO is put low
FESEM shape appearance figure under big multiple, and d, e, f are then three different microwave heating time synthetic materials under high-amplification-factor
FESEM shape appearance figure.In the case of can be seen that low amplification by FESEM shape appearance figure, the Microwave-assisted firing time is 15min
Material scatter preferably, pattern is more homogeneous, regular, and the material of 30 and 60min microwave heating time synthesis all exists necessarily
Reunion phenomenon, wherein 60min synthesis material reunite be particularly acute；In the case of high-amplification-factor, find that 60min adds
The material of hot time preparation is serious due to reuniting, and the size of portion of material is greatly affected with pattern impact, and 15 Hes
The material morphology rule of 30min synthesis, but under the conditions of 15min, the scantling of synthesis is less.Both in the bar of high and low amplification
Under part, scantling prepared by the 15min microwave-assisted time, pattern are more preferable, are because the prolongation with microwave heating time, body
In system, the amount of-OH gets more and more so that resulting materials surface is negatively charged, the reaction residue in easy articulated system or centre
Body, and then with size, impact is produced to pattern.
What Fig. 6 showed is the impact of the photocatalytic activity-time of three kinds of different Microwave-assisted firing time synthetic materials
Curve.It can be seen that with the increase of catalysis time, degradation rate all assumes first rapid increase, after gradually slow down, finally
Reach the trend of balance.From curve, the material of 30min microwave heating time synthesis has a high light catalysis activity, 15min time
It, and the material of used time 60min synthesis is the weakest, final degradation rate is respectively：98.8%th, 94.5% and 83.3%.Mainly because
Material for used time 60min synthesis is reunited seriously so as to be greatly reduced with the contact probability of photon, paranitrophenol, leads to light
Catalysis activity is not high.
By contrast it is found that 15 and 30min Microwave-assisted firing synthetic materials photocatalytic activity gap very little.
Consider size, pattern, photocatalytic activity and the cost of resulting materials, the Microwave-assisted firing time selecting 15min is optimal.
2.4.3 the sign of material and analysis
(1)N2- BET analyzes
Table 4 is shown as the Fe of solvent-thermal method preparation3O4, commercial TiO2And ZnO and Fe of Microwave-assisted synthesis3O4@SiO2@
The N of ZnO2- BET tests characterization result.As seen from table, Fe3O4@SiO2The specific surface area of@ZnO is 3 times of ZnO, is TiO22
Times.Compare ZnO and TiO2, the Fe of present invention synthesis3O4@SiO2In@ZnO unit mass, entrained active site position is more, photon
Utilization ratio is higher.
Table 4Fe3O4、ZnO、TiO2And Fe3O4@SiO2The N of@ZnO2- BET parameter
(2) FESEM analysis
With ethylene glycol as solvent, solvent structure Fe3O4Nano material, has carried out size, morphology analysis to it, such as Fig. 7
Shown in (a), as can be seen from the figure gained Fe3O4Favorable dispersibility, size uniformity, pattern rule.Wherein Fe3O4Nano material
Size Control in ± 50nm, pattern is ball-type, illustrates to receive using suitable dispersant, solvent and preparation method energy effective control
The growth of rice material and synthesis.
Fig. 7 (b) is Fe3O4@SiO2FESEM shape appearance figure.As seen from the figure, ball-type Fe3O4The pattern warp of nano-particle
Cross SiO2Modify and there occurs very big change.By contrast, gained Fe3O4@SiO2The surface profile of material thickens, size
Also affected by certain with pattern, but also illustrated inertia SiO from another point of view2Granule has been coated on ball-type effectively
Fe3O4Surface, prevent it oxidized, improve water solublity, the biocompatibility of material simultaneously.
Under conditions of microwave-assisted, using Zn (CH3COO)2·2H2O, DEG and Fe3O4@SiO2Prepare Fe respectively3O4@
SiO2@ZnO and ZnO nano material.Fig. 7 (c) is ZnO, and Fig. 7 (d-f) is then Fe3O4@SiO2The FESEM figure of@ZnO.Both contrasts
Shape appearance figure it is found that ZnO nano granule there occurs the more serious agglomeration of ratio, in irregular shape, size heterogeneity, and
Fe3O4@SiO2The dispersive property of@ZnO is good, and based on ball-type, size Control is in 80～150nm.Examine three differences of figure to put
The Fe of big multiple3O4@SiO2@appearance of ZnO figure is it is found that Fe is compared on its surface3O4Material seems more coarse, is because that microwave is auxiliary
Help while flash heat transfer, also provide the other stirring action of molecular level, the ZnO nano granule of high-quality can not only be produced,
And can make that it is more dispersed, be more uniformly coated on Fe3O4@SiO2The surface of composite.
(3) XRD analysis
Before and after Fe is coated by contrast3O4With Fe3O4@SiO2The crystalline phase of both XRD diffraction pattern analysis of bi-material with
Purity.Fig. 8 (a) is shown that Fe3O4@SiO2Diffracting spectrum, Fig. 8 (b) is Fe3O4Diffracting spectrum.As can be seen from Fig.,
Fe3O4The all of characteristic diffraction peak of nano material is all corresponded with the standard diffraction peak of spectrogram JCPDS card No.99-0073, its
In 7 characteristic diffraction peaks：2 θ=30.1 °, 35.5 °, 37.1 °, 43.1 °, 53.5 °, 57.0 ° and 62.6 ° corresponding crystal faces are respectively
For：(220), (311), (222), (400), (422), (511) and (440), show that the product synthesizing is with inverse spinel knot
The Fe of structure3O4.Additionally, impurity peaks do not occur in diffracting spectrum, illustrate that the crystal purity synthesizing is very high, crystal along having
(311) crystal face growth of maximum surface free energy.By contrast, Fe3O4@SiO2Characteristic diffraction peak intensity be below Fe3O4Material
Expect, and 37.1 ° of corresponding (222) crystal faces disappear.That is due to inertia SiO2Layer plays protection Fe3O4Effect so that crystal face
Capped, the transmission hindering X-ray to a certain extent is so that diffraction peak intensity weakens.
Fig. 9 respectively illustrates ZnO, Fe3O4And Fe3O4@SiO2The XRD diffracting spectrum of@ZnO.Wherein a, b, c represent respectively
ZnO、Fe3O4And Fe3O4@SiO2The diffraction spectrum of@ZnO.As seen from the figure, 9 principal character diffraction maximum 2 θ=31.7 ° of ZnO,
34.4 °, 36.2 °, 47.5 °, 56.5 °, 62.8 °, 66.3 °, 67.9 ° and 69.0 ° corresponding crystal faces are respectively：(100)、(002)、
(101), (102), (110), (103), (200), (112) and (201), all with standard diagram JCPDS card No.36-1451 in
Characteristic diffraction peak is consistent, and there are not impurity peaks, illustrates that with DEG be solvent, the ZnO of Microwave-assisted synthesis has hexagonal wurtzite
Crystal structure, and crystal purity is very high.In conjunction with Fe3O4With the diffracting spectrum of ZnO, it can be found that Fe3O4@SiO2@ZnO not only has
Fe3O4Characteristic diffraction peak, there is also the characteristic diffraction peak of ZnO.In 2 θ=31.7 °, 34.4 °, 36.2 °, 47.5 °, 56.5 ° and
67.9 ° occur in that obvious ZnO characteristic diffraction peak, and in 2 θ=30.1 °, 35.5 °, 43.1 °, 53.5 ° and 62.6 ° of diffraction maximums correspond to
Be Fe3O4Characteristic diffraction peak, but the obvious skew of composite diffraction maximum does not occur, absolutely prove Fe3O4@SiO2@ZnO is multiple
There is not alloying in synthetic body.In addition, it is apparent that the characteristic diffraction peak peak type of ZnO is sharp and half-peak breadth in Fig. 9 (c)
Narrow, compare Fe3O4Characteristic diffraction peak intensity be substantially eager to excel a lot, and a part of Fe3O4Characteristic diffraction peak disappear, root
May infer that Fe according to a variety of signs3O4Surrounded by ZnO.
(4) FT-IR analysis
Figure 10 is Fe3O4With Fe3O4@SiO2Infrared absorption spectroscopy.Contrast two spectrum it is found that Figure 10 (a) and figure
10 (b) is in 550cm-1Place is respectively provided with an absworption peak, is the stretching vibration peak of Fe-O, and Fe3O4@SiO2Diffracting spectrum Figure 11 (b)
In 958cm-1Place has had more the asymmetric stretching vibration peak of the Si-O being caused by the motion of oxonium ion.Meanwhile, do not find second two
The characteristic absorption peak of alcohol, does not find other impurity peaks yet, shows Fe3O4With Fe3O4@SiO2There is very high purity, SiO2
It is coated on Fe well3O4Surface.
Figure 11 is ZnO, Fe3O4And Fe3O4@SiO2The infrared ray diffraction spectrum of@ZnO.Wherein a, b, c represent respectively ZnO,
Fe3O4And Fe3O4@SiO2The absorption spectrum of@ZnO.From Figure 11 (a), ZnO nano material is in 500cm-1Place absworption peak be
The characteristic absorption peak of Zn-O, 3240cm-1Place's absworption peak is the stretching vibration peak of-OH, and-OH derives from the pyrolysis of DEG；1430 with
1540cm-1Respectively correspond to C-O and C=O stretching vibration peak, absorption peak strength weaker 2857 and 2927cm-1It is then C-H's
Characteristic absorption peak, they derive from-CH3COO, illustrates centrifugation, also has a small amount of-CH after washing3COO remains.From 2-12
C () is it is found that Fe3O4@SiO2@ZnO absorption spectrum possesses Fe3O4The all of characteristic absorption peak with ZnO, but Fe3O4Absorption
Peak will be markedly less than ZnO, illustrates that ZnO has successfully been coated on Fe3O4Surface.
(5) UV-vis DRS analysis
Figure 12 such as is at the different samples of quality is UV-Vis DRS absorption spectrum between 200～800nm in wavelength
(UV-visDRS).A, b, c in Figure 12 represents Fe respectively3O4, ZnO and Fe3O4@SiO2The diffusing reflection spectrum of@ZnO.By Figure 12
A () can be seen that black Fe3O4Nano-particle all has absworption peak in the range of 300～700nm, and its maximum absorption band is than ZnO
With Fe3O4@SiO2@ZnO is much lower, shows Fe3O4Not strong with the responding ability of ultraviolet light to visible ray, there is no photocatalytic degradation
The ability of pollutant.Contrast 2-13 (b) and 2-13 (c) are it is found that ZnO and Fe3O4@SiO2@ZnO is in 200～400nm scope
Inside there is very strong light absorpting ability, show obvious ultraviolet light response ability.But, Fe3O4@SiO2@ZnO there occurs slightly
Red shift, also can have certain responding ability to the light of wavelength bigger beyond ultraviolet light.Because nucleocapsid structure is by different crystal
Composition, between lattice, difference can make shell matter constantly extrude nuclear matter, produce stress-strain effect, ultimately result in composite wood
There is red shift in material band gap.As (Ahv) in Figure 122Shown in-hv curve, by making (Ahv)2- hv curve and cutting that hv axle intersects
ZnO and Fe is calculated after line3O4@SiO2@ZnO energy gap is respectively 3.35eV and 3.21eV, and corresponding optical absorption peak is located respectively
In 370 and 385nm.Interpretation of result shows, multilayer coating structure does not make the photoresponse ability of photocatalyst occur significantly
Reduce, Fe3O4@SiO2@ZnO has outstanding ultraviolet light response ability.
(6) VSM analysis
Figure 13 shows magnetic field intensity when being 20KOe, and under room temperature condition, the magnetic hysteresis of the different magnetic materials of equal quality is returned
Line.A, b, c in Figure 13 represents Fe respectively3O4、Fe3O4@SiO2And Fe3O4@SiO2The hysteresis curve of@ZnO.As seen from the figure,
Fe3O4、Fe3O4@SiO2And Fe3O4@SiO2The coercitive value of@ZnO is respectively less than 5Oe, and illustrative material has all reached the mark of superparamagnetism
Accurate.The saturation magnetic intensity of magnetic material reaches 16.3emu g-1When, when there is externally-applied magnetic field, magnetic material just can be determined
To collecting.Fe3O4、Fe3O4@SiO2And Fe3O4@SiO2The saturation magnetic intensity of@ZnO is respectively 83.1,63.5 Hes
32.5emu·g-1, illustrate that three kinds of materials all show very strong magnetic force performance, be that recycling of catalyst lays the foundation, energy
The cost of effective control catalyst, realizes the commercial Application of catalyst early.
Chapter 3, Fe3O4@SiO2The absorption of@ZnO and Photocatalytic Performance Study
3.1 photocatalytic degradation experiments
Photocatalytic degradation is tested with the simulated wastewater of paranitrophenol as target contaminant, and the photocatalysis inquiring into catalyst are lived
Property and stability.Fe3O4@SiO2@ZnO is with the condition preparation after chapter 2 optimization.TiO2Generally acknowledge at present, photocatalysis performance
Outstanding catalyst, has the energy gap of 3.30eV and outstanding photocatalysis stability.With TiO2Contrasted, more intuitively
Embody Fe3O4@SiO2The quality of@ZnO photocatalysis performance.Mainly investigate the factor of 6 impact properties of catalysts, including：
Light source, catalyst amountses, the initial concentration of waste water, initial pH, the impact to catalyst of light application time and HA concentration, also finally
Carried out catalyst recycles experiment.
3.1.1 photocatalytic degradation influence factor
(1) light source
3 different scenes of principal set up are tested in the impact of light source：Dark, ultraviolet light and sunlight, and in ultraviolet light
Under the conditions of opened up a blank not adding catalyst more.Pipette 25mL 30mg L-1Paranitrophenol in circle
In column type quartz reactor, add some Fe3O4@SiO2@ZnO catalyst, is carried out 10min supersound process and is secretly adsorbed with 30min,
To reach dark adsorption saturation.Under different light sources, light application time is all set as 120min, and reaction takes supernatant to carry out after terminating
Centrifugation, by solution after centrifugation as the extinction measuring paranitrophenol in UV-2550 type ultraviolet-visible spectrophotometer
Value, and calculate degradation rate DR.
(2) catalyst amountses
Pipette 25mL certain density p-nitrophenyl phenol solution to reactor, respectively 0～1.4g L-1Between scope etc.
Every Fe3O4@SiO2@ZnO and TiO2Catalyst is added in reactor, is placed in photochemical reaction instrument after supersound process 10min
Carry out the dark adsorption reaction of 30min, after reaching adsorption-desorption balance, prolonged exposure 120min, take appropriate supernatant to measure wherein
The concentration of paranitrophenol, calculates degradation rate.
(3) initial concentration
Pipetting mass concentration is 0～200mg L-1The p-nitrophenyl phenol solution of variable concentrations change, in reactor, adds
Said determination draws Fe3O4@SiO2@ZnO and TiO2Optimum level dosage, mixed liquor supersound process 10min dark is adsorbed
Reaction 30min, makes system reach adsorption-desorption balance.After ultraviolet light 120min, supernatant analysis is taken to measure DR.
(4) light application time
Under the conditions of above-mentioned optimal factor level, by a certain amount of p-nitrophenyl phenol solution respectively with Fe3O4@SiO2@ZnO
And TiO2Photocatalyst is sufficiently mixed, and is irradiated under mercury lamp through pre-treatment.Irradiation time is adjusted to 0～180min, and
It is sampled at interval of a period of time, sample liquid is placed in the light carrying out 200～700nm scope on spectrophotometer after being centrifuged
Spectrum scanning.Additionally, employing the COD (COD that potassium dichromate method measures the remaining p-nitrophenyl phenol solution of degradedCr),
CODCrClearance η (%) computational methods are as follows：
In formula, CODCrAnd CODCr0It is expressed as t and the COD of initial time degraded solutions.
In order to further appreciate that the contact of absorption-catalysis, expand Fe3O4@SiO2@ZnO is to three kinds of different initial concentrations
The adsorption experiment of p-nitrophenyl phenol solution.Respectively 10, the 30 and 50mg L of 300mL-1P-nitrophenyl phenol solution as taper
In bottle, add a certain amount of catalyst, 30 DEG C of waters bath with thermostatic control are vibrated 240min, taken supernatant at set intervals in light splitting light
Measure light absorption value in degree meter, and calculate clearance.
(5) original ph
On the basis of above-mentioned optimum dosage, light application time and initial concentration, carry out the initial of p-nitrophenyl phenol solution
PH value is 3～10 photocatalytic degradation experiment.In the case of not doing any regulation, the original ph of solution is 6.68.Experiment is adopted
Use 0.1mol L-1HNO3With 1mol L-1NaOH the original ph of solution is adjusted.After pre-treatment, in ultraviolet
It is irradiated under light.After experiment terminates, measure the solution concentration of different original ph, calculate respective DR.Additionally, also carrying out
PH value is 3,7 and 10 Fe3O4@SiO2@ZnO adsorbs paranitrophenol solution experiments.Both certain density for 25mL p-nitrophenyl
Phenol moves in conical flask, the equivalent catalyst of input, and 240min is vibrated in constant temperature water bath with thermostatic control, samples at set intervals, measures
The clearance of sample liquid.
(6) impact of HA
HA is the larger molecular organics matter being widely present in water, and basic structure is nitrogen compound and aromatic compound
Condensation substance, phenyl ring carries the functional groups such as substantial amounts of carboxyl, hydroxyl, carbonyl, quinonyl, methoxyl group, inquires into the concentration of HA in water
Impact to photocatalysis performance can process for actual waste water and provide reliable theoretical foundation.Basis in above-mentioned factor optimum level
On, the concentration of Setup Experiments HA is 0～8mg L-1, after experiment terminates, measure the DR of paranitrophenol in supernatant.
3.1.2 recycle experiment
On the basis of 3.1.1 experimental result, carry out 8 continuous circulation experiments.Operating procedure is as follows：Catalyst is divided
Dissipate the dark adsorption treatment of the supersound process carrying out 10min in paranitrophenol waste water and 30min.In 300W high voltage mercury lamp
Under irradiation, Solar Photocatalytic Degradation of P-nitrophenol solution, take 5mL sample liquid centrifugation at set intervals, measure instantaneous moment
DR.After the Catalysis experiments of a cycle terminate, with Magnet, photocatalyst is oriented collection, and removes molten in reactor
Liquid, rejoins equal-volume, isocyatic paranitrophenol waste water, carries out photocatalysis experiment again, until the 8th continuous circulation
Terminated using experiment.Recycle after experiment terminates, the catalyst being collected with Magneto separate is carried out washing, dried, again
Carry out XRD characterization test.
3.2 photocatalysis results and discussion
3.2.1 the impact of light source
Semiconductor light-catalyst is different to the photoresponse ability of dissimilar light source, big less to frequency of energy gap
Photoresponse ability is strong, little then contrary of energy gap.So, suitable light source be inquire into catalyst light degradation ability primary because
Element.Figure 14 is the impact to catalyst light degradation p-nitrophenyl phenol solution for the light source.Can draw there is no the feelings of illumination from figure
Under condition, Fe3O4@SiO2@ZnO can remove in solution 12.7% paranitrophenol.Characterization result shows, Fe3O4@SiO2@ZnO is only
There is photoresponse ability to the light for below 800nm for the wavelength, and it is seen that the ratio that light accounts for is 20 times of ultraviolet light in sunlight,
Both visible ray can be replaced with sunlight.ZnO photocatalyst due to energy gap larger it is seen that the responding ability of light is not strong, but by
Figure can be seen that Fe3O4@SiO2@ZnO also can preferably degrade p-nitrophenyl phenol solution under visible light, and degradation rate reaches
47.3%, it is because that its unique structure can effectively expand photoresponse scope.From blank, paranitrophenol is in ultraviolet
Auto-degradation poor ability under light, illumination 120min only degrades 3.1%, and adds Fe3O4@SiO2After@ZnO photocatalyst,
Degradation rate improves 87.6%.Although Fe3O4@SiO2@ZnO has certain responding ability to visible ray, but under ultraviolet light conditions
Photocatalytic pollutant degradation more thorough, so ultraviolet light is more suitable for Fe3O4@SiO2@ZnO carries out photocatalytic degradation organic contamination
Thing.
3.2.2 the impact of catalyst amountses
In Photocatalytic Degradation Process, the attribute that catalyst itself possesses determines the power of its photocatalytic activity, but
Different reaction conditions also can photocatalytic degradation result produce significant impact.Figure 15 is the dosage of catalyst to photocatalysis
The impact of degradation experiment.As illustrated, with Fe3O4@SiO2@ZnO and TiO2The increase of photocatalyst dosage, degraded takes the lead in
Gradually gentle after rapid increase, and it is finally reached stable.This trend mainly due to when dosage is relatively low, the work of catalyst
Property point position limited it is impossible to make full use of light source offer photon, lead to the photoelectron-hole exciting to lazy weight it is impossible to produce
Enough OH and O of life2 -Carry out catalytic oxidation process.With the increase of catalyst amountses, photon energy is effectively utilised,
So degradation rate assumes the trend of swift and violent growth.However, be not catalyst amount The more the better.Because when catalyst gradually increases
Many, collision probability between granule increases, nano-particle easily occur to reunite and so that photocatalytic activity point position does not increase anti-fall；With
When, the increase of catalyst also can make photon be difficult to pass through solution, produces light masking phenomenon；Additionally, occurring the probability of light scattering to increase
Plus be also a key factor causing degradation rate lifting difficult.So, the dosage with catalyst increases, and degradation rate is final
Trend towards steadily.Illustrate that suitable catalyst amountses can improve photocatalytic degradation efficiency, and can effective control cost.Catalysis
Agent concentration is 0.4g L-1When, in energy degraded solutions, 91.2% paranitrophenol, does not result in waste, is therefore chosen as being catalyzed
The optimum dosage of agent.
The photocatalytic degradation curve of two kinds of different catalysts of contrast is it is found that compare TiO2, Fe3O4@SiO2@ZnO is combined
The photocatalytic activity of photocatalyst is higher.Because, inherently a kind of outstanding photocatalyst of one side ZnO；On the other hand,
The Fe of nucleocapsid structure3O4@SiO2@ZnO specific surface area is bigger, does not only have higher photon utilization rate, and can be photoelectron-sky
Cave, to providing more attachment point positions, stops quickly being combined of photoelectron-hole pair, and then photocatalytic activity is increased
By force.Illustrate that the present invention prepares the Fe of gained3O4@SiO2@ZnO magnetic nano photochemical catalyst material possesses very strong photocatalytic activity.
3.2.3 the impact of initial concentration
Characteristic according to photocatalyst selects suitable pollutant initial concentration just can carry out efficiently photocatalytic degradation, saves
Cost.Therefore, investigate the impact to properties of catalyst for the catalytic substrate concentration and seem particularly significant.Figure 16 is Fe3O4@SiO2@
ZnO and TiO2Dosage be 0.4g L-1On the basis of, investigate paranitrophenol initial concentration in 0～200mg L-1Model
Enclose the impact to photocatalyst.As illustrated, with the increase of paranitrophenol concentration, delaying occurs in the degradation rate of two kinds of catalyst
Slow decline.Initial concentration is 30mg L-1When, Fe3O4@SiO2@ZnO and TiO2Degradation rate higher, respectively 91.2% He
84.7%；And initial concentration is 200mg L-1When, both photocatalytic activity difference as little as 19.4% and 12.4%.This
The reason photocatalyst is with the increase of catalytic substrate concentration, the phenomenon that degradation efficiency appearance reduces in various degree is broadly divided into：One
Aspect, the increase of concentration of substrate is so that the contaminant molecule in reactor increases, and photoelectron-hole that photocatalyst produces
To limited amount, lead to catalysis oxidation scarce capacity, contaminant degradation is not thorough；On the other hand it is due to paranitrophenol itself
Color there is certain light absorptive, the transmission ability of the higher photon of concentration is lower, and catalyst surface can be by more right
Nitrophenol molecule surrounds, and the probability that photon contacts with catalyst greatly reduces, and in a disguised form reduces the intensity of ultraviolet light, leads to
The reduction of photocatalytic activity.
The degradation rate curve of two kinds of catalyst of contrast it is found that during low concentration, Fe3O4@SiO2@ZnO can effectively stop electricity
To being combined, its catalytic degradation efficiency is higher than TiO in son-hole2；With the increase of concentration of substrate, the probability contacting photon becomes
Low, then energy gap is higher, the more preferable TiO of ultraviolet light response ability2Photonexcited electron-hole pair can more effectively be utilized；
In addition, the photocatalysis stability of magnetic composite will be slightly poorer to TiO during high concentration2Material, is also to lead to its degradation rate to be less than
TiO2A principal element.So, the present invention prepares the Fe of gained3O4@SiO2@ZnO magnetic nano photochemical catalyst material is at low bottom
Very strong photocatalytic activity is shown during thing concentration, but, improving its performance in high concentration of substrate is that we will send out from now on
Exhibition and the direction made great efforts.
In order to further appreciate that the contact of the absorption-degradation property of catalyst, investigate Fe3O4@SiO2@ZnO absorption is different
The impact of the paranitrophenol-time of initial concentration.As can be seen from Figure 17,10,30,50mg L-1Initial concentration solution
In the range of 30～45min, all reach adsorption equilibrium, such as：Initial concentration is 30mg L-1, Fe3O4@SiO2@ZnO saturation is adsorbed
Capacity is 9.8mg g-1.But, the Photocatalytic activity of catalyst is but very strong.This is due to the life-span in photoelectron-hole pair
Extremely short, pollutant must adsorb in advance and just can carry out photocatalytic degradation on the surface of catalyst, reach one quickly absorption-
Desorption process, the rapid replacement of new pollutant is decomposed, could improve the photocatalytic activity of catalyst.As illustrated, when dirt
Dye thing initial concentration is 50mg L-1When, catalyst surface has adsorbed the paranitrophenol molecule of excess, leads to photocatalysis performance
Reduce.So, through comprehensive analysis and consideration, dark adsorption time selects 30min, and the initial concentration of p-nitrophenyl phenol solution selects
30mg·L-1.
3.2.4 the impact of light application time
The length of light application time is inseparable with the height of the disposal efficiency, and general light application time is longer, catalytic degradation
Efficiency is higher.Therefore, inquire into catalyst optimum light application time tool to be of great significance.Figure 18 is shown that Fe3O4@
SiO2During@ZnO Solar Photocatalytic Degradation of P-nitrophenol, solution not COD in the same timeCrValue.As illustrated, paranitrophenol gives up
The COD in water 0min momentCrIt is worth for 60.2mg L-1, through the photocatalytic degradation of 90min, its CODCrValue drops to 7.6mg L-1, i.e. CODCrClearance is up to 87.4%.Additionally, by block diagram as can be seen that CODCrValue declines in the range of 30～60min
Degree is maximum, degradation efficiency highest now.Illustrate that paranitrophenol, by successful mineralising, is Photocatalytic Oxidation.
From the influence curve of paranitrophenol photocatalytic activity-light application time, continue the ultraviolet lighting of 180min
Penetrate, paranitrophenol auto-degradation rate is only 3.5%.So, the physicochemical property of paranitrophenol is sufficiently stable.Two kinds of catalyst
Degradation rate curve all with the increase of light application time and rapid increase, then gradually slow down, be finally reached balance.Compare it
Under, the photocatalytic degradation initial stage, TiO2Catalytic degradation speed faster, through the ultraviolet light of 30min, just degraded
50.1% p-nitrophenyl phenol solution, and now Fe3O4@SiO2The catalysis degradation modulus of@ZnO are 43.6%.After 90min, Fe3O4@
SiO2The performance of@ZnO is better than TiO2.Through the ultraviolet light of 180min, solution eventually becomes colourless, transparent liquid.By
In structure, the nature difference of nano material, cause both to adsorb the ability difference of pollutant, lead to two kinds of catalyst of catalysis initial stage
Photocatalytic activity there is gap.Absorption is inseparable with photocatalytic degradation, and absorption, as a supporting process, promotees
Enter the carrying out of photocatalytic degradation.But the increase with light application time, photoelectron-hole that catalyst excites is to progressivelying reach one
Optimum state, Fe3O4@SiO2The catalytic degradation ability of@ZnO is better than TiO2.Fe3O4@SiO2@ZnO in light application time is
The catalysis degradation modulus of 120min and 180min are respectively 90.8% and 98.5%, both gap very littles.Because through after a while
Ultraviolet light, the paranitrophenol molecule in solution gradually decreases, with OH and O2 -Contact probability diminish, so fall
Solution rate rises slow.So selecting 120min to be Fe3O4@SiO2During the optimum illumination of@ZnO photocatalyst degraded paranitrophenol
Between.
Figure 19 is shown that light application time is 0～180min, and p-nitrophenyl phenol solution in the same time is not in 200～700nm
In the range of ultraviolet-ray visible absorbing scanning optical spectrum.As seen from the figure, light application time increases, and paranitrophenol feature at 401nm is inhaled
The intensity receiving peak is but gradually reduced, and finally vanishes from sight, in conjunction with CODCrThe change of collection of illustrative plates it is believed that after Catalysis experiments terminate,
There is not paranitrophenol molecule in solution.In catalytic process, the maximum absorption band of paranitrophenol occurs in that red shift,
412nm is moved to by 401nm it may be possible to due to the cracking of phenyl ring ,-NO in degradation process2Produce in the middle of the disengaging of group and generation
Thing leads to.
3.2.5 the impact of original ph
The original ph of solution can change catalyst and the charge characteristic on pollutant surface, also can affect dividing of catalyst
Scattered property and OH and O2 -Formation, so investigate catalyst photocatalytic degradation optimum pH be significant.Figure 20 is
Under condition of different pH, the maximum absorption wavelength change curve of paranitrophenol molecule in solution.As illustrated, paranitrophenol exists
Under conditions of alkalescence and neutrality, a length of 401nm of maximum absorption wave；Its in acid condition, maximum absorption wavelength then be 317nm.
Additionally, p-nitrophenyl phenol solution is under the conditions of different pH, maximum absorption wavelength does not all occur significantly to offset, basicly stable
317 or 401nm, both paranitrophenol molecule had preferable stability in the case of different pH value.
Figure 21 is the impact of solution difference original ph-adsorption capacity.Experiment is to be 30mg L in initial concentration-1Base
Carry out on plinth.As seen from the figure, the front 30min that the adsorption capacity curve of 3 different original ph is carried out in experiment is all steady
Step rise, but original ph be 3 and 10 adsorption capacity with adsorption experiment carrying out, occur drastically decline.But pH value is 7
Adsorption capacity but still maintain higher level, show when pH close to neutral when, the absorbability of catalyst, stability
All reach optimal.
Figure 22 is the impact of solution difference original ph-the disposal efficiency.As illustrated, solution original ph is 3～10
In the range of, Fe3O4@SiO2@ZnO and TiO2The degradation rate curve of catalyst all assumes elder generation and first gradually rises, and decline rapidly afterwards becomes
Gesture.Fe3O4@SiO2@ZnO optimum photocatalytic degradation pH value is 8, degradation rate now is up to 93.5%, strong acid, highly basic
Environment all can not effectively improve the photocatalytic activity of catalyst.Due to, under strong acid condition, there are a large amount of H in solution+, p-nitrophenyl
The free electron on phenol surface is susceptible to protonation ,-NO2On oxygen atom be susceptible to protonation, stop to nitre
Base phenol molecule is contacted with the surface of catalyst, makes OH and O2 -It is hardly formed, so degradation rate is not high；When there is highly basic ring
During border, substantial amounts of OH-Make catalyst surface negatively charged, lead to the Van der Waals force between paranitrophenol and catalyst and electrostatic
Effect significantly weakens, and the absorption property of catalyst substantially reduces so that the photocatalytic activity of catalyst declines.Additionally, ZnO shell
It is one kind typically optimum oxide, have certain dissolving under strong acid and strong base.Although Fe3O4@SiO2@ZnO is strong in pH
Performance under acid, highly basic has declined, but minimum degradation rate still can reach 83.8%, and can be seen that from curve
TiO2Show undesirable in the case of strong acid, highly basic,, when pH value is 10, degradation rate is down to 72.7% for it.So, preparation institute
The Fe obtaining3O4@SiO2@ZnO has wider pH subject range, and it is better than TiO to the adaptability of pH change2Photocatalyst.
3.3.6HA impact
HA is prevalent in natural water body as a kind of larger molecular organicses, mainly by C, H, O, N and micro S, P etc.
Elementary composition, carry abundant active group, these groups enable it to have excellent absorption, ion exchange, complexation and sequestration
Power.So, the impact to catalyst degradation performance for the concentration of HA in discussion solution has great practical significance.Figure 23 is that HA is dense
Spend for 0～8mg L-1Under the conditions of, the impact of two kinds of photocatalyst for degrading paranitrophenols.As illustrated, Fe3O4@SiO2@ZnO
And TiO2With the increase of HA concentration, first slow rising is presented to the degradation rate of organic pollution, rapid downward trend afterwards.
HA concentration is 0.5,3 and 8mg L-1When, degradation rate is respectively 90.1%, 98.7% and 88.2%.It is primarily due to：Low concentration
When HA pore volume aperture be provided that substantial amounts of absorption surface, being quickly combined of photoelectron-hole pair can be prevented, and HA with to nitro
Van der Waals force between phenol and electrostatic attraction can make the paranitrophenol molecule of catalyst surface quickly be desorbed, catalyst
The increased activity of catalyst can be led to combined with new paranitrophenol molecule generation again；HA has certain extinction in itself
Property, when HA is in high concentration, in solution, substantial amounts of HA molecule is also easy to produce mutually exclusive, so that the utilization rate of photon is reduced, and HA energy
With paranitrophenol, catalyst and other material in solution chelate, complexation and ion exchange, ultraviolet light is produced and hides
Cover, so that degradation rate is declined.Two kinds of different catalyst of contrast, it can be found that HA is to Fe3O4@SiO2The facilitation of@ZnO is more
Substantially, because the Fe after modifying3O4@SiO2@ZnO magnetic nanometer composite material has more preferable water solublity and substances compatible
Property, Fe3O4@SiO2@ZnO is more stable in the environment.In summary, when HA concentration is in 2～5mg L-1In the range of when, can strengthen
Fe3O4@SiO2The photocatalytic activity of@ZnO.
3.3.7 recycle performance evaluation
In the actual application of catalyst, the stability of catalysis material and recycle ability ever more important.Fe3O4@
SiO2@ZnO photocatalyst has outstanding magnetic response ability, and in the case of there is externally-applied magnetic field, photocatalyst can be by rapidly
Directional collecting.Figure 24 is Fe3O4@SiO2The catalysis degradation modulus of the continuous circulation experiment of 8 times of@ZnO photocatalyst are over time
Impact.As seen from the figure, compare the 1st cycle, the degradation rate of paranitrophenol occurs in that in 7 circulation experiments subsequently carrying out
Slight decline.Wherein, the degradation rate in the 1st cycle and the 8th cycle is respectively 90.8% and 82.3%, shows Fe3O4@
SiO2@ZnO recycles experiment through 8 times, and catalysis degradation modulus do not occur and significantly decline.Two adjacent cycles,
The degradation rate of paranitrophenol about differs 1%, shows Fe3O4@SiO2After@ZnO photocatalyst is recycled for multiple times, still have relatively
Strong photocatalytic activity and very high stability.Slight decline occurs be because：On the one hand it is catalyst in Magneto separate mistake
A small amount of loss occurs in journey；On the other hand it is that photoetch effect makes the active site bit quantity of catalyst surface reduce.So,
Fe3O4@SiO2@ZnO has the good ability that recycles, in actual applications great development potentiality.
Figure 25 is the forward and backward X-ray diffraction spectra of 8 circulation experiments of catalyst.Two collection of illustrative plates of contrast are it is known that 8 times circulate
Test that forward and backward XRD spectrum is basically identical, be only the change that the intensity of both diffraction maximums occurs somewhat.Diffraction maximum before catalysis
After being slightly better than catalysis, it is that catalyst occurs a small amount of loss to lead to.Again show that the Fe of present invention synthesis3O4@SiO2@ZnO magnetic
Property nano composite photo-catalyst has very high photocatalysis stability.
Chapter 4, models fitting and Analysis on Mechanism
4.1 catalytic kineticses models
Conventional catalytic model has Langmuri-Hinshelwood kinetic model (L-H model).By to experiment number
According to carrying out models fitting, explain and inhale the rule that Photocatalytic Degradation Process meets.
L-H kinetic model is the adsorption process embodying reactant by Langmuir Isothermal Model, and assumes surface
React the determiner for system reaction rate, evaluated with the performance to catalyst.I.e. reactant is in solid catalyst table
Quick adsorption-desorption process is occurred on face, the level of coverage on catalyst surface becomes positive correlation to reaction rate with reactant.
Wherein, the slope of linear relationship represents light-catalyzed reaction speed constant；
Work as KadC>>When 1, KadC+1≈KadC, catalyst reaches adsorption saturation state to reactant, meets zero order reaction, side
Formula can be expressed as：
C=C0-k0t (4-1)
Work as KadC<<When 1, KadC+1 ≈ 1, that is, catalyst adsorption saturation state is reached far away to reactant, meet one-level anti-
Should, equation can be expressed as：
Wherein, KadAdsorption equilibrium coefficient (L mg for reaction-1)；k0(mg·(L·min)-1) and k ' (min-1) respectively
Represent the reaction rate constant of zero level and first-order model；C0For reactant initial concentration (mg L-1)；C represents the concentration of reactant
(mg·L-1)；T is catalysis time.
4.2 experimental technique
Pipette 25mL certain density p-nitrophenyl phenol solution in eight circle of position column type quartz reactors of photochemical reaction instrument
Interior, it is separately added into the Fe of equivalent3O4@SiO2@ZnO or TiO2, after 10min ultrasonic disperse and the dark adsorption treatment of 30min, in
Under 300W mercury lamp, take 5mL sample liquid centrifugation at set intervals, be placed in UV-2550 type ultraviolet-visible spectrophotometer,
Measure the concentration of paranitrophenol, and carry out L-H models fitting and obtain catalytic kineticses major parameter.
4.3 model analysiss
According to formula (4-1), formula (4-2), with t as abscissa, respectively with C0- C and ln (C0/ C) it is vertical coordinate, to Fe3O4@
SiO2@ZnO and TiO2The experimental data of Solar Photocatalytic Degradation of P-nitrophenol carries out linear fit.Figure 26 respectively illustrates Fe3O4@
SiO2The zero order reaction kinetics of@ZnO photocatalyst and the linear fit curve of pseudo-first order reaction kinetics, the power simulating
Learn model parameter to be shown in Table 5.From Figure 26 and Figure 27, pseudo-first order reaction kinetics models fitting linearly preferable, from table 5
In understand, the coefficient R of two kinds of catalyst pseudo-first order reaction kinetics models is greater than zero order reaction kinetics, R1 2It is respectively
0.985 and 0.989, Fe is described3O4@SiO2@ZnO and TiO2The surface adsorption ability of photocatalyst is weak, Fe3O4@SiO2@ZnO and
TiO2The process of Solar Photocatalytic Degradation of P-nitrophenol more meets pseudo-first order reaction kinetics model.Fe3O4@SiO2@ZnO and TiO2's
Pseudo-first order reaction kinetics reaction constant is respectively 0.024 and 0.018min-1, show Fe3O4@SiO2@ZnO photocatalytic degradation pair
The Mean Speed of nitrophenol compares TiO2Faster, photocatalytic activity is higher.
Table 5 photodegradation kinetics linear fit parameter
4.4 enhanced photocatalytic mechanisms are inquired into
Fe is understood according to photocatalysis experiment3O4@SiO2@ZnO has high light catalysis activity.Wherein, Fe3O4Photoresponse ability
Poor, this is consistent with the characterization result of UV-vis DRS, and that play a key effect is Multifunctional housing ZnO, so ZnO
Photocatalytic mechanism, also for Fe3O4@SiO2The photocatalytic mechanism of@ZnO.Exist between the conduction band (CB) of ZnO and valence band (VB)
Forbidden band, their energy difference is referred to as energy gap.The band gap of general energy gap is wider, and energy difference is bigger, excite photoelectron-
Hole is bigger to the photon energy needing.Photoelectron-hole to be produce OH and O2 -Key, and OH and O2 -Again
Can further degradation of contaminant.The photocatalysis dominant mechanism of ZnO is shown in below equation, and schematic diagram is as shown in figure 28：
ZnO+hv→ZnO(eCB -+hvB +) (4-3)
The present invention prepares the Fe of gained3O4@SiO2The photocatalytic activity of@ZnO magnetic nanometer composite material is better than TiO2Receive
Rice photocatalyst, is primarily due to Fe3O4@SiO2The specific surface area of@ZnO reaches 27.52m2·g-1, TiO2Specific surface area only
For 12.15m2·g-1It is known that Fe3O4@SiO2The specific surface area of@ZnO is TiO22 times, on the one hand it be provided that more activity
The utilization ratio of photon, to absorb photon, is improved in point position；On the other hand more attachment point positions can be provided to photoelectron again, prevent
Quickly being combined of photoelectron-hole pair, improves the photochemical catalytic oxidation ability of material.In addition studies have found that, be exposed to catalyst
The Fe on surface3+, it can effectively catch light induced electron, and reaction generates Fe2+, and the Fe of less stable2+Again easily and in system
Dissolved oxygen reaction generate Fe3+, considerably reduce photoelectron-hole probability compound to generation.Reaction formula is as follows, illustrates
Figure is as shown in figure 29：
eCB -+Fe3+→Fe2+(4-7)
Inquire into the process that paranitrophenol is progressively degraded in light-catalyzed reaction, contribute to us and more profoundly understand this
Class compound is by the mechanism of photocatalytic degradation.In Fe3O4@SiO2In@ZnO suspension, paranitrophenol is different by two kinds
Approach is by catalysis oxidation：The Oxidation that the mutual transfer of the hydroxylating of aromatic rings and electronics, proton causes.No matter which kind of way
Footpath, OH and O2 -All play vital role etc. the free radical of strong oxidizing property.It is special that OH has very strong electrophilic
Property, easily electron density highest carbon atom on aromatic rings is launched a offensive, so the attribute of carbon atom is to determine on aromatic rings
Reaction carries out the key of which kind of catalytic route.When OH attacks the carbon atom carrying unpaired electron on aromatic rings, its C-O key
It is susceptible to rupture, ultimately result in the cracking of aromatic rings；When OH attacks the carbon atom of stable in properties on aromatic rings, aromatic rings
On-NO2It is susceptible to depart from, is replaced by-OH, constantly attacked by OH, the product of two kinds of approach occurs mutually to turn
Change, be finally gradually degraded to intermediate product or the inorganic molecules product of nonhazardouss.The catalytic degradation machine of two kinds of different approaches
Reason is shown in Figure 30.
Embodiment 2
A kind of Fe3O4@SiO2The preparation method of@ZnO magnetic nanometer photocatalyst, comprises the steps：
(1) it is Zn (CH according to w/v3COO)2·2H2O:DEG=2.0g:90mL mixes, and ultrasonic wave added dispersion
Min, then in microwave power be 550W, temperature be 145 DEG C under conditions of heat 5min, obtain the first intermediate reaction liquid；(2) press
It is Fe according to w/v3O4@SiO2:DEG=0.15g:15mL mixes, and ultrasonic wave added dispersion 10min, then in microwave work(
Rate is 550W, temperature heats 5min under conditions of being 145 DEG C, obtains the second intermediate reaction liquid；(3) according to volume parts meter, will
90 part of first intermediate reaction liquid and the mixing of 15 part of second intermediate reaction liquid, then microwave power be 550W, temperature be 155 DEG C
Under the conditions of heat 15min, obtain mixed reaction solution；(4) reactant liquor to be mixed is cooled to room temperature, centrifugation, washes solid
The DEG solution of residual, after vacuum drying, obtains Fe3O4@SiO2@ZnO magnetic nanometer photocatalyst, is stored in drying tower.
Described Fe3O4@SiO2It is prepared by the following method：
(1) according to volume parts meter, the ammonia that 1 part of mass fraction is 25% is mixed with 1.8 parts of dehydrated alcohol, is configured to
Ammonia-ethanol solution；(2) according to volume parts meter, 1 part of tetraethyl orthosilicate is mixed with 8 parts of dehydrated alcohol, is configured to positive silicic acid
Ethyl ester-ethanol solution；(3) first count by weight, by 0.8 part of Fe3O4It is mixed to get the first mixture with 0.8 part of sodium citrate
Material, adds the ratio of 240mL dehydrated alcohol and 240mL deionized water to the first mixed material according still further to every gram of first mixed material
Middle addition dehydrated alcohol and deionized water, ultrasonic disperse 10min, obtain Fe3O4Disperse system；(4) first according to volume parts meter, point
Do not measure 13 parts of ammonia-ethanol solution, 10 parts of tetraethyl orthosilicate-ethanol solution and 220 parts of Fe3O4Disperse system, then by positive silicic acid
Ethyl ester-ethanol solution and ammonia-ethanol solution are gradually dropped Fe simultaneously3O4Disperse system, in course of reaction, by Microwave-assisted firing
Make temperature of reaction system maintain 68 DEG C, and carry out lasting mechanical agitation, the response time is 20min；(5) products therefrom is carried out
Centrifugation, washing, after vacuum drying, obtain Fe3O4@SiO2, it is stored in drying tower.
Described Fe3O4It is prepared by the following method：
(1) count by weight, by 120 parts of FeCl3·6H2O, 340 parts of CH3COONa and 10 part of sodium citrate mixing is all
Even obtain the second mixed material, according still further to every gram second mixed material add 8～10 milliliters of ethylene glycol bulking value ratio to
Add ethylene glycol in second mixed material, be uniformly mixing to obtain mixed liquor；(2) mixed liquor is transferred to politef hydro-thermal anti-
Answer in kettle, make reactor temperature be 190 DEG C Muffle furnace in heat 8h, be then centrifuged for separate, washing, be dried, obtain single point
Scattered Fe3O4Nano material.
Embodiment 3
A kind of Fe3O4@SiO2The preparation method of@ZnO magnetic nanometer photocatalyst, comprises the steps：
(1) it is Zn (CH according to w/v3COO)2·2H2O:DEG=2.5g:110mL mixes, and ultrasonic wave added divides
Scattered 12min, then in microwave power be 650W, temperature be 155 DEG C under conditions of heat 8min, obtain the first intermediate reaction liquid；
(2) it is Fe according to w/v3O4@SiO2:DEG=0.25g:20mL mixes, and ultrasonic wave added dispersion 12min, then in micro-
Wave power is 650W, temperature heats 8min under conditions of being 155 DEG C, obtains the second intermediate reaction liquid；(3) according to volume parts
Meter, by 110 part of first intermediate reaction liquid and the mixing of 25 part of second intermediate reaction liquid, then microwave power be 650W, temperature be
Heat 20min under conditions of 165 DEG C, obtain mixed reaction solution；(4) reactant liquor to be mixed is cooled to room temperature, centrifugation, cleaning
Fall the DEG solution of solid residue, after vacuum drying, obtain Fe3O4@SiO2@ZnO magnetic nanometer photocatalyst, is stored in drying tower
Interior.
Described Fe is prepared using improved sol-gal process3O4@SiO2, step is as follows：
(1) according to volume parts meter, the ammonia that 1 part of mass fraction is 25% is mixed with 2.2 parts of dehydrated alcohol, is configured to
Ammonia-ethanol solution；(2) according to volume parts meter, 1 part of tetraethyl orthosilicate is mixed with 12 parts of dehydrated alcohol, is configured to positive silicon
Acetoacetic ester-ethanol solution；(3) first count by weight, by 1.2 parts of Fe3O4It is mixed to get the first mixing with 1.2 parts of sodium citrates
Material, adds the ratio of 260mL dehydrated alcohol and 260mL deionized water to the first mixture according still further to every gram of first mixed material
Add dehydrated alcohol and deionized water, ultrasonic disperse 12min in material, obtain Fe3O4Disperse system；(4) first according to volume parts meter,
Measure 17 parts of ammonia-ethanol solution, 12 parts of tetraethyl orthosilicate-ethanol solution and 280 parts of Fe respectively3O4Disperse system, then by positive silicon
Acetoacetic ester-ethanol solution and ammonia-ethanol solution are gradually dropped Fe simultaneously3O4Disperse system, in course of reaction, by microwave-assisted plus
Heat makes temperature of reaction system maintain 72 DEG C, and carries out lasting mechanical agitation, and the response time is 30min；(5) products therefrom enters
Row centrifugation, washing, after vacuum drying, obtain Fe3O4@SiO2, it is stored in drying tower.
Described Fe is prepared using solvent-thermal method3O4, step is as follows：
(1) count by weight, by 150 parts of FeCl3·6H2O, 380 parts of CH3COONa and 20 part of sodium citrate mixing is all
Even obtain the second mixed material, add the bulking value ratio of 10 milliliters of ethylene glycol to second according still further to every gram of second mixed material
Add ethylene glycol in mixed material, be uniformly mixing to obtain mixed liquor；(2) mixed liquor is transferred to politef hydrothermal reaction kettle
In, make reactor temperature be 210 DEG C Muffle furnace in heat 10h, be then centrifuged for separate, washing, be dried, obtain monodispersed
Fe3O4Nano material.
Claims (3)
1. a kind of Fe3O4@SiO2The preparation method of@ZnO magnetic nanometer photocatalyst is it is characterised in that comprise the steps：
(1) it is Zn (CH according to w/v3COO)2·2H2O:DEG=2.0～2.5g:90～110mL mixes, and ultrasonic auxiliary
Help dispersion 10～12min, then in microwave power be 550～650W, temperature be 145～155 DEG C under conditions of heating 5～
8min, obtains the first intermediate reaction liquid；
(2) it is Fe according to w/v3O4@SiO2:DEG=0.15～0.25g:15～20mL mixes, and ultrasonic wave added dispersion
10～12min, then in microwave power be 550～650W, temperature be 145～155 DEG C under conditions of heat 5～8min, obtain
Second intermediate reaction liquid；
(3) according to volume parts meter, by 90～110 part of first intermediate reaction liquid and 15～25 part of second intermediate reaction liquid mixing,
Then microwave power be 550～650W, temperature be 155～165 DEG C under conditions of heat 15～20min, obtain hybrid reaction
Liquid；
(4) reactant liquor to be mixed is cooled to room temperature, centrifugation, washes the DEG solution of solid residue, after vacuum drying, obtains
To Fe3O4@SiO2@ZnO magnetic nanometer photocatalyst, is stored in drying tower.
2. preparation method as claimed in claim 1 is it is characterised in that described Fe3O4@SiO2It is prepared by the following method：
(1) according to volume parts meter, the ammonia that 1 part of mass fraction is 25% is mixed with 1.8～2.2 parts of dehydrated alcohol, prepares
Ammonification water-ethanol solution；
(2) according to volume parts meter, 1 part of tetraethyl orthosilicate is mixed with 8～12 parts of dehydrated alcohol, be configured to tetraethyl orthosilicate-
Ethanol solution；
(3) first count by weight, by 0.8～1.2 part of Fe3O4It is mixed to get the first mixture with 0.8～1.2 part of sodium citrate
Material, adds the ratio of 240～260mL dehydrated alcohol and 240～260mL deionized water to the according still further to every gram of first mixed material
Add dehydrated alcohol and deionized water, ultrasonic disperse 10～12min in one mixed material, obtain Fe3O4Disperse system；
(4) first according to volume parts meter, 13～17 parts of ammonia-ethanol solution, 10～12 parts of tetraethyl orthosilicate-ethanol are measured respectively
Solution and 220～280 parts of Fe3O4Disperse system, then tetraethyl orthosilicate-ethanol solution and ammonia-ethanol solution are gradually dripped simultaneously
Enter Fe3O4Disperse system, in course of reaction, makes temperature of reaction system maintain 68～72 DEG C by Microwave-assisted firing, and carries out continuing
Mechanical agitation, the response time be 20～30min；
(5) products therefrom is centrifuged, washing, after vacuum drying, obtains Fe3O4@SiO2, it is stored in drying tower.
3. preparation method as claimed in claim 2 is it is characterised in that described Fe3O4It is prepared by the following method：
(1) count by weight, by 120～150 parts of FeCl3·6H2O, 340～380 parts of CH3COONa and 10～20 portion of Fructus Citri Limoniae
Sour sodium mix homogeneously obtains the second mixed material, adds the weight of 8～10 milliliters of ethylene glycol according still further to every gram of second mixed material
Volume ratio adds ethylene glycol in the second mixed material, is uniformly mixing to obtain mixed liquor；
(2) mixed liquor is transferred in politef hydrothermal reaction kettle, makes the Muffle that reactor is 190～210 DEG C in temperature
Heat 8～10h in stove, be then centrifuged for separating, washing, be dried, obtain monodispersed Fe3O4Nano material.
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| CN113979509A (en) * | 2021-11-05 | 2022-01-28 | 北京农学院 | Application of ultrathin sheet metal hydroxide in antibiotic degradation |
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| WO2009026141A1 (en) * | 2007-08-17 | 2009-02-26 | University Of Florida Research Foundation, Inc. | Supercrystalline colloidal particles and method of production |
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