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CN108479759A - A kind of visible-light response type La doped wolframic acid bismuth catalyst and preparation method thereof - Google Patents

A kind of visible-light response type La doped wolframic acid bismuth catalyst and preparation method thereof Download PDF

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CN108479759A
CN108479759A CN201810373222.6A CN201810373222A CN108479759A CN 108479759 A CN108479759 A CN 108479759A CN 201810373222 A CN201810373222 A CN 201810373222A CN 108479759 A CN108479759 A CN 108479759A
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catalyst
doped
wolframic acid
acid bismuth
preparation
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CN108479759B (en
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钟爽
孙锐
李晨阳
张凤君
吕晨
李明
吴磊
韩言锋
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Jilin Jianzhu University
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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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/24—Chromium, molybdenum or tungsten
    • B01J23/31—Chromium, molybdenum or tungsten combined with bismuth
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/30—Treatment of water, waste water, or sewage by irradiation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/38—Organic compounds containing nitrogen

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Abstract

A kind of visible-light response type La doped wolframic acid bismuth catalyst of present invention offer and preparation method thereof, belongs to photocatalysis technology field, La doped wolframic acid bismuth catalyst is by bismuth nitrate (Bi (NO3)3·5H2O), lanthanum chloride (LaCI3·7H2O), sodium tungstate (Na2WO4·2H2O sediment) is made through solvent thermal reaction in ethylene glycol, then will be made after washing of precipitate and drying, La doped ratio is 2 10wt% in the La doped wolframic acid bismuth catalyst.La‑Bi2WO6Catalyst has good photocatalysis performance, can be used for photocatalysis degradation organic contaminant, especially antibiotic contamination.When La doping ratios are 5%, La Bi2WO6Photocatalysis effect it is best.Under the simulated solar irradiation irradiation condition of 300W xenon lamps, catalyst is up to 96.25% to the removal rate for the tetracycline that initial concentration is 30mg/L.

Description

A kind of visible-light response type La doped wolframic acid bismuth catalyst and preparation method thereof
Technical field
It is specially a kind of suitable for the visible light-responded of sewage disposal the present invention relates to a kind of catalyst and preparation method thereof Type La doped wolframic acid bismuth catalyst and preparation method thereof, belongs to photocatalysis technology field.
Background technology
In recent years, the abuse of antibiotic compound makes not only all there are different journeys in soil, deposit in water body The residue of degree detects situation[1].Antibiotic compound usually has degradation half life shorter compared with POPs.But by In the substance in animal husbandry and a large amount of uses of culture fishery, constantly supplemented into environment, it in the environment can be with Reach the accumulative effect of " lasting ", therefore the antibiotic contamination is known as "false" persistent pollutant[2-3]。
It is not currently both at home and abroad very ripe to the research of the practical degradation technique of tetracycline wastewater[4,5], therefore research and develop new Treatment technology, so that the degradation effect of tetracycline antibiotics is obviously improved using the method being simple and efficient is becoming current state Inside and outside research hotspot.Antibiotic minimizing technology more conventional at present has biological treatment[6], physisorphtion[7], chemistry at Reason method etc..Wherein method of chemical treatment includes general chemistry facture and advanced chemical oxidation technology (AOPs) again.Compared to Biological treatment is long operation cycle, biotoxication phenomenon easily occurs, physisorphtion is the separation for realizing tetracycline compound It can not achieve the purpose that removal degradation, general chemistry facture Meteorological are higher, easily cause the disadvantage of secondary pollution etc., it is high Grade oxidation technology with the process of its simple and flexible and not will produce secondary pollution environment friendly it is more widely accepted For suitable antibiotic contamination minimizing technology.Photocatalysis oxidation technique is exactly one kind of high-level oxidation technology, using partly leading Body photochemical catalyst pollutant difficult to degrade in generating the free radical material with strong oxidizing property under illumination condition to waste water carries out Thoroughly oxidation and removal.Therefore, photocatalysis technology is as a kind of emerging high-level oxidation technology, in the processing of tetracycline wastewater Aspect has broad prospects and research significance[8]。
Photocatalysis technology originates from late 1970s, is a kind of emerging using redox reaction as the sewage of principle Treatment technology.Photochemical catalyst is often used some special semi-conducting materials, by the difficult to degrade of some complexity under the conditions of normality The thorough oxygenolysis of noxious material is converted into CO2、H2The substances such as O have valence compared with traditional physical sewage water treatment method Lattice are cheap, reaction condition require it is relatively low, the advantages that reaction product harmless non-secondary pollution[9]。
Bismuth tungstate semiconductor light-catalyst is modified, codope rare earth element introduce defect and nonmetalloid into Enter lattice and substitutes O.Synergistic effect can be generated, light induced electron-is reduced while reducing semiconductor light-catalyst energy gap The recombination rate in hole, to greatly improve the photocatalytic activity of catalyst[10-12]。
Using photocatalysis technology, modified bismuth tungstate photocatalyst is added into Tri-Biocin under the driving of visible light Object-quadracycline is reacted, and it is CO that can make the final mineralising of tetracycline2、H2O、NH4 +Equal substances, to make pollutant obtain Effectively to remove[13].Therefore, it is had broad prospects using photocatalysis technology processing tetracycline wastewater, for high concentration The improvement of antibiotic compound pollutant effluents provides certain theoretical foundation.
Bismuth tungstate (Bi2WO6) it is a kind of perofskite type oxide, have by WO6(Bi2O2)2+The sandwich-like of composition Perovskite-like lamellar structure.Bi2WO6Energy gap be only 2.69eV, can more effectively absorb visible light, and Bi2WO6 Special sandwich configuration and photoelectricity characteristic so that it has certain foreground in terms of water pollution control.Bi2WO6Although With TiO2Compared to the response section for having widened visible light, but the recombination rate of its photo-generate electron-hole is still very high, photocatalysis effect Fruit is still not ideal enough.Therefore, to being modified, its band gap width is further decreased, and reduce answering for photo-generate electron-hole Conjunction rate becomes the research hotspot of current novel bismuth series photocatalyst.
The method that being modified at present to semiconductor light-catalyst makes its photocatalysis performance be improved and improve has metal Element/nonmetal doping, surface deposited metal or metal oxide, semiconductors coupling etc., can be effectively by modification Energy gap is reduced, to make the red shift of absorption band edge and further decrease the recombination rate of photo-generated carrier.This research uses rare earth Lanthanoid metal element doping semiconductor light-catalyst bismuth tungstate prepares La-Bi2WO6Visible light responsive photocatalyst.Rare earth lanthanum element Doping the main reason for alloing the activity of photochemical catalyst to increase be attributed to the following：
1. lanthanide series rare-earth elements have, special and active 4f electron structures, this be advantageous to electronics transition and The formation of new energy level can reach the effect that photochemical catalyst absorbs band edge red shift by thulium and wolframic acid dopping effect Fruit.The doping of rare earth element can make bismuth tungstate that distortion of lattice occur, to generate lattice defect so that the conduction band and valence of script With occurring new intermediate level i.e. doped energy-band between energy level, energy gap narrows, and is conducive to electronics and transition occurs and improves Responsiveness of the catalyst to visible light.
2. the generation of lattice defect effectively inhibits photo-generate electron-hole pair as the trap center of photo-generated carrier It is compound, enable the progress that light-catalyzed reaction is lasting.
3. the doping of rare earth element inhibits the growth of bismuth tungstate crystal, crystallite dimension is made to become smaller, it is effectively increased to urge The migration rate of the specific surface area of catalyst particles, photo-generated carrier greatly improves, catalyst to the utilization rate of visible light also Enhancing[14]。
4. in relation to studies have shown that rare earth element ion has certain oxygen storage capacity, when the oxygen concentration in reaction solution is high Shi Jinhang stores up oxygen, and oxygen release is carried out when oxygen concentration is too low.And the oxygen for being adsorbed on catalyst surface is main light induced electron capture Agent can react with light induced electron and generate peroxide O2 -, inhibit the compound of light induced electron and hole[15]。
It can be seen that using the method for Rare Earth Lanthanum element doping to Bi2WO6Photochemical catalyst is modified, and is had and is improved Bi2WO6The practical application of the potential quality of photocatalytic activity, efficient process and photocatalysis technology to tetracycline wastewater has centainly Significance for Environment.
[1] Ge Linke, Zhang Siyu, Xie Qing wait photochemistry behavior [J] the Chinese sciences of antibiotic in water environment:Change It learns, 2010 (2):124-135.
[2] it going into business good jade, Hu Jianying, Sun Jianxian wait pharmaceuticals in environment and personal care articles [J] chemical progress, and 2009 (z1):389-399.
[3]Watkinson AJ,Murby E J,Kolpin D W,et al.The occurrence of antibiotics in an urban watershed:from wastewater to drinking water.[J] .Science of the Total Environment,2009,407(8):2711-23.
[4] Zheng's pendant, Qin Fang, white wave wait .TiO2@carbon nanotube adsorptions remove quadracycline [J] environmental project journals, 2015,9(8):3615-3624.
[5] Lu Changyu, Guan Wei are saved, and Peng Yuexin waits .TiO2The ion-exchanged of nanotube and photocatalysis are gone four in water removal Research [J] Beijing University of Chemical Technology's journals (natural science edition) of ring element, 2015,42 (1):81-86.
[6] it is big to show Adsorption law and its mechanism study [D] Nankai of the wealth tetracycline antibiotics on activated sludge by Song It learns, 2014.
[7]Ahmed M B,Zhou J L,Ngo H H,et al.Adsorptive removal of antibiotics from water and wastewater:Progress and challenges[J].Science of the Total Environment,2015,532:112-126.
[8]Yahiaoui I,Aissani-Benissad F,Fourcade F,et al.Removal of tetracycline hydrochloride from water based on direct anodic oxidation(Pb/ PbO2,electrode)coupled to activated sludge culture[J].Chemical Engineering Journal,2013,221(2):418-425.
[9]Kubacka A,M,G.Advanced nanoarchitectures for solar photocatalytic applications.[J].Chemical Reviews,2016,112(3):1555-614.
[10] Wang Ye, Li Bin, Dong Lihui wait .Tb3+Adulterate Bi2WO6The preparation of photochemical catalyst and its Photocatalytic Performance Study [J] Guangxi University journal natural science edition, 2014 (6):1378-1384.
[11] Zou Xuejun, Dong Yuying, Sun Hongjie wait .F/Ce to adulterate Bi2WO6Orange [J] the water of visible light photocatalysis oxidation methyl Resource and Hydraulic Projects journal, 2016,27 (1):54-58.
[12]Wang D,Shen H,Li G,et al.La and F co-doped Bi2MoO6architectures with enhanced photocatalytic performance via synergistic effect[J].Rsc Advances,2016,6(75).
[13] the refreshing .Bi of clock2WO6The preparation of base visible light catalyst and in a continuous flow reactor degradation tetracycline wastewater Research [D] Jilin University, 2016.
[14] Chen Jianhua, Wang Xiaolin, Zhang Peixin wait nano titanium dioxide powder ion dopings research [J] Guangxi University Journal (natural science edition), 2005,30 (1):44-50.
[15] the red rare earth mixing with nano TiO of Hou Ting2Structure and characteristic electron research [D] Sichuan Universitys, 2006.
Invention content
The present invention is directed to currently with the inefficient problem of single bismuth tungstate photocatalyst processing antibiotics waste water, Utilize the special nature of rare earth lanthanum element, it is proposed that a kind of visible-light response type La doped wolframic acid bismuth catalyst, it is visible to improve Photocatalysis technology is to the removal efficiency of antibiotic in water body, in addition, the invention also provides the preparation methods of above-mentioned catalyst.
In order to solve the above technical problems, the present invention is achieved by following technical solution：
A kind of visible-light response type La doped wolframic acid bismuth catalyst is by bismuth nitrate (Bi (NO3)3·5H2O), chlorination Lanthanum (LaCI3·7H2O), sodium tungstate (Na2WO4·2H2O precipitation) is made through high-temperature high-voltage reaction in ethylene glycol, it then will precipitation It is made after washing and drying, La doped ratio is 2-10wt% in the La doped wolframic acid bismuth catalyst.
Preferably, the bismuth nitrate, lanthanum chloride, sodium tungstate molar ratio be 1:(0.04-0.2):2.
A kind of preparation method of visible-light response type La doped wolframic acid bismuth catalyst, includes the following steps：
S1, by bismuth nitrate (Bi (NO3)3·5H2O it) is dissolved in ethylene glycol, while by lanthanum chloride (LaCI3·7H2O it) adds Into in above-mentioned solution, magnetic agitation obtains solution A to entirely molten；
S2, with beaker by sodium tungstate (Na2WO4·2H2O it) is dissolved into ethylene glycol (EG), obtains solution B, magnetic agitation is extremely Quan Rong；
S3, solution B is poured slowly into solution A, continuing stirring 1.0-2.0h with magnetic stirring apparatus makes solution be uniformly mixed After be transferred in autoclave that the reaction was complete, cooled to room temperature；
S4, upper liquid is poured out after catalyst fines completely sedimentation after opening kettle, is 1 by volume with ethyl alcohol and water:1 Mixed cleaning solution cleans repeatedly, finally discards supernatant liquid and dries bottom catalyst in baking oven, will be catalyzed with agate mortar Agent is ground to careful powdered to get to finished product La doped wolframic acid bismuth catalyst (La-Bi2WO6)。
Preferably, the molar ratio 1 in the step S1 between bismuth nitrate, lanthanum chloride, sodium tungstate:(0.04-0.2):2.
Calculate mass according to amount mol and the relative molecular mass of substance, then divided by bismuth tungstate quality, obtained quality Score 2-10wt%.
Preferably, temperature is 160 DEG C -180 DEG C in the step S3 mesohigh reaction kettles, reaction time 16-24h.It is high Pressure is difficult to detect in warm autoclave, and pressure is weighed by temperature, and temperature more high pressure is bigger.In closed high temperature In autoclave, pressure when reaching above-mentioned temperature is required pressure in the present invention.
Preferably, wash number is 3-5 times in the step S4, and temperature is 50-80 DEG C in the baking oven.
Compared with prior art, the technique effect that the present invention has is as follows：
(1) present invention is used prepares La-Bi by a step solvent-thermal method of solvent of ethylene glycol2WO6Catalyst, preparation process Simply, without adjusting solution ph, preparation condition is mild, is not influenced on the crystal phase structure of bismuth tungstate after rear earth lanthanum doping, this The prepared La-Bi of invention2WO6Catalyst crystal degree is high, pattern is uniform.
(2) La-Bi prepared by the present invention2WO6Catalyst has good photocatalysis performance, can be used for photocatalytic degradation Organic pollution, especially antibiotic contamination.When La doping ratios are 5wt%, La-Bi2WO6Photocatalysis effect most It is good.Under the simulated solar irradiation irradiation condition of 300W xenon lamps, removal rate of the catalyst to the tetracycline that initial concentration is 30mg/L Up to 96.25%, than the Bi of undoped La2WO6Catalyst degradation rate (88.92%) improves 7.33%.
(3) La-Bi prepared by the present invention2WO6After there is catalyst good stability, 4 repetitions to test, catalyst 90.44% is still up to the removal rate of tetracycline.Such catalyst has in terms of handling organic pollutants widely answers Use foreground.
Description of the drawings
Fig. 1 is La-Bi2WO6The XRD spectrum of catalyst series；Wherein, (a)：0%La-Bi2WO6；(b)：2%La- Bi2WO6；(c)：5%La-Bi2WO6；(d)：10%La-Bi2WO6；
Fig. 2 is scanning electron microscopic observation catalyst sample microscopic appearance and distribution of particles figure；Wherein, (a) is pure Bi2WO6It sweeps Retouch electron microscope；(b) it is La-Bi2WO6Scanning electron microscope (SEM) photograph；
Fig. 3 is 5%La-Bi2WO6The energy spectrum diagram of catalyst；
Fig. 4 is 5%La-Bi2WO6The transmission electron microscope picture of catalyst；Wherein, (illustration is (a) transmission electron microscope surface texture figure Electron diffraction diagram) (b) high-resolution-ration transmission electric-lens figure；
Fig. 5 is La-Bi2WO6UV-Vis DRS abosrption spectrogram (UV-Vis)；Wherein, (a) UV-Vis collection of illustrative plates；(b) Absorption band edge graph；
Fig. 6 is La-Bi2WO6The infrared spectrogram of catalyst series；
Fig. 7 is 5%La-Bi2WO6Xps energy spectrum analysis chart；Wherein, (a)：Full figure is composed；(b)：Bi4f；(c)：W4f；(d)： O1s；(e)：La 3d；
Fig. 8 is La-Bi2WO6Degradation effect figure of the catalyst to tetracycline；(a) different doping ratio photochemical catalyst photocatalysis Degradation quadracycline curve；(b) adsorption curve figure of the different doping ratio photochemical catalysts to quadracycline；
Fig. 9 is 5%La-Bi2WO6The repetition empirical curve of catalyst.
Specific implementation mode
To keep the technical problem to be solved in the present invention, technical solution and advantage clearer, below in conjunction with attached drawing and tool Body embodiment is described in detail.
The present invention is carried for the inefficient problem of existing single bismuth tungstate photocatalyst processing antibiotics waste water A kind of visible-light response type La doped wolframic acid bismuth catalyst is supplied.
Visible-light response type La doped bismuth tungstate (La-Bi2WO6) using solvent-thermal method preparation, specific method is catalyst： By the bismuth nitrate (Bi (NO of 4mmol (1.9393g)3)3·5H2O it) is dissolved in 40mL ethylene glycol, while by the chlorine of different proportion Change lanthanum (LaCI3·7H2O it) adds into aforesaid liquid, obtains solution A -1 (lanthanum chloride 0.0149g=0.04mmol is added), A-2 (lanthanum chloride 0.0743g=0.2mmol is added) in (be added lanthanum chloride 0.0371g=0.1mmol), A-3, and magnetic agitation 1h is to complete It is molten；Use 100mL beakers by the sodium tungstate (Na of 2mmol (0.6596g) simultaneously2WO4·2H2O), it is dissolved into the ethylene glycol of 30mL (EG) 5 parts of identical solution Bs are obtained in, magnetic agitation 1h is to complete molten；Solution B is slowly poured into solution A -1, A-2 respectively, In A-3, continuing stirring 30min with magnetic stirring apparatus makes solution be transferred to after mixing in 100mL autoclaves, in 160- 16-24h, cooled to room temperature are reacted under the conditions of 180 DEG C.Upper liquid is fallen after catalyst fines completely sedimentation after opening kettle Go out, is 1 with ethyl alcohol and water mixed proportion:1 cleaning solution cleans 3-5 times repeatedly, each 30min.Liquid is finally discarded supernatant the bottom of by Portion's catalyst is dried in 50-80 DEG C of baking oven, is ground to catalyst with agate mortar careful powdered to get to finished product La-Bi2WO6Catalyst series, La doping ratios are respectively 2wt%, 5wt%, 10wt%.
In addition, preparing bismuth tungstate (Bi2WO6) catalyst as a comparison, preparation method is as follows：
By the bismuth nitrate (Bi (NO of 4mmol (1.9393g)3)3·5H2O it) is dissolved in 40mL ethylene glycol, obtains solution A, Magnetic agitation 1h；Simultaneously using the beaker of 100mL by the sodium tungstate (Na of 2mmol (0.6596g)2WO4·2H2O) it is dissolved into 30mL Ethylene glycol (EG) in, obtain solution B, magnetic agitation 1h；Solution B is slowly poured into solution A, magnetic stirrer is used 30min makes solution be transferred to after mixing in the autoclave that liner range is 100mL, reacts 20h under the conditions of 160 DEG C, Cooled to room temperature.Upper liquid is poured out after catalyst fines completely sedimentation after opening kettle, with ethyl alcohol and water mixed proportion It is 1:1 cleaning solution cleans 3-5 times repeatedly under magnetic stirring, each 30min.It finally discards supernatant liquid bottom catalyst exists It dries, is ground to catalyst with agate mortar careful powdered to get bismuth tungstate (Bi in 60 DEG C of baking ovens2WO6) catalyst.
Different doping is arranged than determining that the best photochemical catalyst of activity is mixed by carrying out photocatalytic degradation experiment in the present invention Miscellaneous ratio is carried out at the same time the characterization tests such as XRD, SEM, TEM, observes the internal structure and optical absorption characteristics of material.Change not Same experiment primary condition, probes into influence of the different condition to photocatalysis effect, so that it is determined that the optimum response of photocatalytic degradation Condition completes the research to doping type visible light catalysts.
La-Bi2WO6Catalyst and Bi2WO6Characterization test interpretation of result
1, XRD analysis
Variation of the different doping than the crystal the Nomenclature Composition and Structure of Complexes of catalyst is investigated with XRD, as shown in Figure 1.
Pure Bi as can be seen from Figure 12WO6The characteristic diffraction peak of (La doped is than 0%) and standard PDF cards #73-2020 mono- It causes, and peak intensity is higher, therefore illustrates that the catalyst crystal degree prepared is preferable, complete crystal form.With the catalyst of La dopings Characteristic diffraction peak and pure Bi2WO6Almost the same, but with the increase of La dopings, the intensity of diffraction maximum gradually weakens, crystal face is to 2 Θ augment directions have offset.This is because the doping of rare earth element plays inhibition grain growth, unit cell volume is made to decline, than Surface area increases.La3+Ionic radius be 0.103nm, with Bi3+Ionic radius it is identical, this illustrates La3+Replace Bi3+It is not brilliant The main reason for grain becomes smaller.The reason of crystal grain reduction crystallinity reduces is that the doping of Rare Earth Lanthanum inhibits the shape of bismuth tungstate nucleus Complete crystal structure cannot be formed by generating defect at, structure cell and distortion of lattice occurring, but with crystallite or unformed shape Little particle exists.
2, sem analysis
Scanning electron microscopic observation catalyst sample microscopic appearance and distribution of particles are as shown in Figure 2.
Fig. 2 (a) is that amplification factor is Bi under 40000 times2WO6Scanning electron microscope (SEM) photograph, it can be seen that the catalyst prepared is in Reveal the spherical uniform distribution of particle, the generation of internal reunion bulky grain may be added drop-wise to after catalyst ultrasound pre-treatment Number is excessive on silicon chip so that it is related that scattered catalyst generates adhesion reunion again.Examine each catalyst granules It can be seen that rough laminated structure.Fig. 2 (b) is that amplification factor is 5%La-Bi under 40000 times2WO6Scanning electron microscope Figure, it can be seen that the catalyst granules of doping 5%La elements is more fine and closely woven, more uniformly spreads, disperses.But still show table The rough sheet-like particle sphere structure in face.
In addition, passing through 5%La-Bi2WO6Energy spectrum diagram (Fig. 3) it can be seen that La elements be successfully doped into Bi2WO6It urges In agent.Bi2WO6Main composition element be C, O, Si, W, Bi, Au, wherein Si elements to carry catalyst sample when self-scanning Silicon chip, C and O elements may be that solvent-thermal method prepare the use of ethylene glycol in catalyst, and metal spraying introduces when Au is scanning electron microscope. 5%La-Bi2WO6Energy spectrum diagram in add La elements, illustrate La-Bi2WO6It is prepared by success.
3, tem analysis
Pure Bi is chosen in all samples2WO6, 5%La-Bi2WO6Two samples are research object, and TEM points are carried out to it Analysis, as shown in Figure 4.
Fig. 4 (a) is 5%La-Bi2WO6Transmission electron microscope surface texture figure (illustration is electron diffraction diagram), can be with from figure Find out that the catalyst sample particle of preparation is uniformly dispersed, show particle size 10nm-20nm grain structure.Diffraction in figure The cyclic structure of glass mark may indicate that catalyst sample belongs to polycrystalline structure.It can be bright from Fig. 4 (b) high-resolution-ration transmission electric-lens figures It is aobvious to see there are the different lattice fringe of two kinds of extending directions, both are measured by using Digital Micrograph softwares Different crystal faces shows that fringe spacing is 0.315nm and 0.272nm, corresponds to Bi respectively2WO6(131) crystal face and (200) it is brilliant Face, it is corresponding with XRD diffraction maximums.
4, UV-Vis is analyzed
Band structure is an important factor for influencing catalyst activity, and the catalyst that different La are adulterated with ratio carries out ultraviolet spectra Analysis is as shown in Figure 5.
Fig. 5 is La-Bi2WO6UV-Vis DRS abosrption spectrogram (UV-Vis).It can be seen that preparing from Fig. 5 (a) Catalyst visible region (within the scope of ＞ 400nm) have certain absorbing amount, light absorpting ability 5%La-Bi2WO6Most Greatly, 10%La-Bi2WO6It is minimum.Apparent red shift is produced to can see optical absorption edge after rare earth doped element in bismuth tungstate, La-Bi2WO6The absorption rate of visible light in sunlight is had been significantly improved.Fig. 5 (b) is by tangential method in different doping Tangent line is done in the absorption curves of ratio can obtain 0%, 2%, the absorption band of the photochemical catalyst of 5%, 10%La doping ratios Side wave length is followed successively by 386nm, 412nm, 415nm, 420nm, and seeing below formula (1) by conductor material Intrinsic Gettering wavelength equation can To show that the energy gap (band gap width) of each doping ratio catalyst is followed successively by 2.98eV, 2.95eV, 2.84eV, 3.01eV. With increasing for La dopings, the energy gap of the semiconductor light-catalyst of preparation is lower, to the responsiveness of visible light It increases, but work as doping ratio more than certain value to make, continues to increase with doping ratio, energy gap is no longer reduced and risen instead Height also decreases to the responsiveness of visible light.It can be obtained from UV-Vis DRS abosrption spectrogram, preparation is urged The doping ratio that the photocatalysis performance of agent is best is 5%La-Bi2WO6。
λg=1240/ Δ Eg (1)
In formula 1, long wavelength threshold λgUnit be nm；ΔEgUnit is eV.
5, FT-IR is analyzed
Infrared spectrum analysis is carried out to judge chemical bonding structure existing for its inside, as shown in Figure 6 to catalyst sample.
Fig. 6 is different doping ratio La-Bi2WO6The infrared spectrogram (FT-IR) of catalyst.In 3500cm-1、1590cm-1 Place is the absorption peak of-OH (O-H) bending vibrations, this is because absorbing the moisture in air when catalyst sample exposes in air It is caused.Positioned at 1380cm-1The absorption peak at place is caused by N-O bending vibrations, this is because containing in catalyst preparation raw material There is NO3-Presence.This it appears that the main absorption section band of catalyst sample is located at 400-1000cm from figure-1Between, It is mainly Bi-O, W-O, W-O-W bending vibrations in the absorption peak of this low wavestrip section.But we are it can also be seen that work as La Doping ratio it is excessively high 10% when, be located at the catalyst absorption peak unobvious of low band.
6, XPS analysis
In XPS analysis, it can carry out qualitatively to analyze the member of each substance in product according to the location of electron binding energy Plain type measures the surface composition of sample, that is, determines the chemical valence of element.
XPS compose full scanning can preliminary judgement sample surface chemical composition.It is scanned one by the full spectrum to sample We can detect wholly or largely element in secondary measurement.In order to obtain the accurate location in conjunction with energy, the chemistry of element is identified State carries out narrow region high-resolution close scanning to the element that needs are identified.
Fig. 7 is 5%La-Bi2WO6The x-ray photoelectron spectroscopy figure of catalyst, (a) full figure compose (b) Bi4f (c) W4f (d) O1s (e) La 3d combine energy it can be seen that the element that catalyst sample includes mainly is Bi, W, O, La from Fig. 7 (a) wherein in sample The nytron pollutant carried essentially from instrument itself positioned at the C1s of 284.6eV.Fig. 7 (b) can be seen that the XPS of Bi4f There are two obvious characteristic peaks in figure, i.e. combination can be the Bi4f at 159.1e V7/2Bi4f5/2 at track spectral peak and 164.3eV Track spectral peak, this with lot of documents report to go out peak position identical, it was demonstrated that 5%La-Bi2WO6Bi ions are deposited with+trivalent in sample .Fig. 7 (c) be sample W4f XPS analysis collection of illustrative plates, electron binding energy appear in 35.2eV and 37.5e V correspond to W4f5/2 and The inner electron of W4f7/2 illustrates that the valence state of W is+6 valences, identical as document report.Fig. 7 (e) shows the 284.6eV of La3d tracks There is electron binding energy characteristic peak in place, corresponds to+the presence of trivalent La elements.Further illustrate La3+Into Bi2WO6In lattice, To improve the light-catalyzed reaction performance of catalyst.Asymmetric peak shows sample surfaces there are two in O1s collection of illustrative plates in Fig. 7 (d) The oxygen of kind compound state.Swarming fitting result shows, is Bi in conjunction with that can be peak at 530.4eV2WO6Lattice Oxygen in crystal (Olatt), Bi-O keys and W-O keys are derived from.In conjunction with the absorption oxygen that can belong to sample surfaces for the peak at 531.8eV (Oads)。
The determination of La doping ratios
Using quadracycline as target contaminant, drop of the different La doping than photochemical catalyst is carried out under 450W xenon sources Solution tests and completes corresponding absorption property and investigates as shown in Figure 8.
From Fig. 8 (a) it can be seen that the catalyst activity for being doped with earth La increases compared with bismuth tungstate. (turn on light 150min) bismuth tungstate only has 88.92% to the removal rate of a concentration of 30mg/L tetracyclines when reaction time is 180min, 2%La-Bi2WO6Removal rate be 90.73%, and 5%La-Bi2WO6Removal rate be up to 96.25,10%La-Bi2WO6Go Except rate is reduced to 92.06% again.Therefore there is the optimum doping ratios of rare earth La for explanation.When doping ratio is less than optimum doping Than when, photochemical catalyst fails to generate the trap of enough capture photo-generated carriers, therefore electron-hole pair cannot efficiently separate To which best catalytic performance cannot be reached.When reaching optimum doping ratio, the separation of electron-hole reaches optimum degree, this When photocatalysis effect it is best.But with further increasing for doping, Bi2WO6Surface electronic cloud (charge layer) thickness is subtracted Small, at this moment only the transmission depth of ultraviolet light can again be dropped with charge layer consistency of thickness, the separation of level of electron-hole pair Low, the photocatalysis performance of photochemical catalyst is declined again.Therefore there is optimum doping ratios.
Observation chart 8 (b) is it can be seen that the adsorption saturation time of different catalysts is 30min or so, in 30min- The concentration level of tetracycline is almost unchanged during 180min.It can be seen that absorption property height is 10%La- from adsorption curve Bi2WO6＞ 5%La-Bi2WO6＞ 2%La-Bi2WO6＞ Bi2WO6。
Catalyst stability is investigated
To the 5%La-Bi of preparation2WO6The investigation that catalyst carries out photocatalysis stability is as shown in Figure 9.
Fig. 9 is catalyst stability figure, the 5%La-Bi as can be seen from the figure prepared2WO6Catalyst is carrying out 4 times four Ring element (30mg/L) degradation repeats to show preferable stability in experimentation.Observe that catalyst utilizes again from figure When tetracycline adsorption levels are substantially reduced, but reflect what same time removal rate was gradually reduced in Photocatalytic Degradation Process Phenomenon.This may be cleaned due to only carrying out the simple agitation of catalyst with ethyl alcohol every time, carry out degradation experiment after drying again. Therefore cleaning process is not thorough the Catalyst Adsorption performance that will have a direct impact on preparation, so cause to the adsorbance of tetracycline and Removal rate all declines.Repeat after the experiment of 4 catalyst degradations the removal rate (90.44%) of tetracycline and the 1st time (96.60%) it compares and is declined slightly, this is also related to the loss of catalyst fines in experimentation.Through weighing, and add for the first time After 0.05g is measured compared to the 4th degradation, catalyst residue 0.041g, loss late is about 18%.In conclusion the present embodiment Prepared La-Bi2WO6Composite catalyst has relatively stable photocatalytic activity under visible light conditions.
The above is the preferred embodiment of the present invention, it is noted that for those skilled in the art For, without departing from the principles of the present invention, several improvements and modifications can also be made, these improvements and modifications It should be regarded as protection scope of the present invention.

Claims (6)

1. a kind of visible-light response type La doped wolframic acid bismuth catalyst, which is characterized in that it is by bismuth nitrate, lanthanum chloride, tungsten Precipitation is made through high-temperature high-voltage reaction in ethylene glycol in sour sodium, then will be made after washing of precipitate and drying, the La doped tungsten La doped ratio is 2-10wt% in sour bismuth catalyst.
2. La doped wolframic acid bismuth catalyst according to claim 1, which is characterized in that the bismuth nitrate, lanthanum chloride, wolframic acid The molar ratio of sodium is 1:(0.04-0.2):2.
3. a kind of preparation method of visible-light response type La doped wolframic acid bismuth catalyst, which is characterized in that include the following steps：
S1, bismuth nitrate is dissolved in ethylene glycol, while lanthanum chloride is added into above-mentioned solution, magnetic agitation is obtained to entirely molten Solution A；
S2, sodium tungstate is dissolved into ethylene glycol with beaker, obtains solution B, magnetic agitation is to complete molten；
S3, solution B is poured slowly into solution A, continuing stirring with magnetic stirring apparatus, so that solution is transferred to high pressure after mixing anti- Answer in kettle that the reaction was complete, cooled to room temperature；
S4, upper liquid is poured out after catalyst fines completely sedimentation after opening kettle, is 1 by volume with ethyl alcohol and water:1 mixing Cleaning solution clean repeatedly, finally discard supernatant liquid and dry bottom catalyst in baking oven, ground catalyst with agate mortar It is milled to careful powdered to get to finished product La doped wolframic acid bismuth catalyst.
4. the preparation method of La doped wolframic acid bismuth catalyst according to claim 3, which is characterized in that in the step S1 Molar ratio 1 between bismuth nitrate, lanthanum chloride, sodium tungstate:(0.04-0.2):2.
5. the preparation method of La doped wolframic acid bismuth catalyst according to claim 3, which is characterized in that in the step S3 Temperature is 160 DEG C -180 DEG C in autoclave, reaction time 16-24h.
6. the preparation method of La doped wolframic acid bismuth catalyst according to claim 3, which is characterized in that in the step S4 Wash number is 3-5 times, and temperature is 50-80 DEG C in the baking oven.
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CN111774053A (en) * 2020-07-06 2020-10-16 重庆工程职业技术学院 Method for preparing dysprosium-doped nano-sheet bismuth tungstate photocatalyst
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CN114075074B (en) * 2020-08-17 2023-03-14 厦门稀土材料研究所 Rare earth doped tungstate-based high-entropy ceramic and preparation method thereof
CN114075074A (en) * 2020-08-17 2022-02-22 厦门稀土材料研究所 Rare earth doped tungstate-based high-entropy ceramic and preparation method thereof
CN112007633A (en) * 2020-09-15 2020-12-01 西北矿冶研究院 La/Bi2WO6Preparation method and application of photocatalyst
CN113231099A (en) * 2021-05-21 2021-08-10 吉林大学 Preparation and application of Z-type polypyrrole-bismuth tungstate photocatalyst
CN113769779A (en) * 2021-08-16 2021-12-10 中化学朗正环保科技有限公司 Photocatalyst for treating amine-containing organic matter sewage and preparation method and application thereof
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