CN103949242A

CN103949242A - Method for preparing bismuth tungstate (Bi2WO6) flaky nano-material

Info

Publication number: CN103949242A
Application number: CN201410122390.XA
Authority: CN
Inventors: 吴庆生; 秦宇航
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2014-03-28
Filing date: 2014-03-28
Publication date: 2014-07-30
Anticipated expiration: 2034-03-28
Also published as: CN103949242B

Abstract

The invention relates to a method for preparing bismuth tungstate (Bi2WO6) flaky nano-material having high-efficiency visible-light photocatalytic activity. The conventional bismuth tungstate nano-material consists of flaky nano-particles gathered and stacked in a ball shape. While according to the invention, the bismuth tungstate nano-material, prepared by adopting a one-step hydrothermal method and through adjusting solvent proportion, consists of dispersed nano flakes. The obtained nano flakes are uniform in thickness and are highly dispersed. The flaky structure enables crystal faces with photocatalytic activity of the material to be exposed at the maximum, such that the material has extremely high photocatalytic activity. Besides, the material has selectivity, and is greatly different in absorption and degradation of different organic dyes. The method for preparing the flaky nano-material is simple, and low in cost, and the flaky nano-material has wide application prospects in the field of wastewater treatment.

Description

Bismuth tungstate (Bi 2wO 6) preparation method of flake nano material

Technical field

The invention belongs to material technology field, relate to a kind of bismuth tungstate (Bi ₂wO ₆) preparation method of flake nano material.

Background technology

From Fujishima in 1972 and Hongda, since " Nature " delivers about TiO2 photodissociation water, semiconductor light-catalyst just must be studied by extensive as a kind of new catalysis material.The reported first such as Kudo in 1999 bismuth tungstate be greater than at wavelength under the visible radiation of 420 nm and there is photocatalytic activity, its energy gap (about 2.7eV), can have by excited by visible light and under visible ray higher catalytic activity.Exactly because such characteristic, bismuth tungstate is used as a kind of novel catalysis material and has caused increasing concern.

At visible light-responded lower bismuth tungstate (Bi ₂wO ₆) degrading organic dye waste water effectively, therefore, bismuth tungstate is at degradable organic pollutant, and waste water control field has very important practical value.

Traditional tungstates photochemical catalyst is normally with the preparation of high-temperature calcination method, this process has not only consumed a large amount of energy, and the sample particle size of preparing is large, and the specific area of catalyst reduces greatly, though can realize visible light-respondedly, photocatalysis efficiency is unsatisfactory.Although the hydro-thermal method extensively adopting has solved the problems such as high energy consumption and too low reference area, the bismuth tungstate nano particle synthesizing is mostly gathering, stacking form, cannot make material light catalysis activity crystal face must expose to greatest extent.Cannot make the photocatalysis performance of bismuth tungstate nano material obtain maximum representing.

Summary of the invention

The object of the invention is to overcome the above the deficiencies in the prior art that approach most, discloses a kind of monodispersed bismuth tungstate (Bi ₂wO ₆) preparation method of nano lamellar material, the method only adopts one step hydro thermal method synthetic, very simple, with low cost, less demanding to equipment; Nano-sheet structural material of the present invention is compared gathering in the past, the material of stacked has more efficient photocatalytic activity, and meanwhile, the absorption to different dyes and degraded also have compared with high selectivity.

The technical scheme providing is:

A kind of bismuth tungstate (Bi ₂wO ₆) preparation method of flake nano material, it is characterized in that, comprise the following steps: according to Na ₂wO ₄2H ₂o and Bi (NO ₃) ₃5H ₂the amount of substance of O is than sampling for 1:2, by Na ₂wO ₄2H ₂o and Bi (NO ₃) ₃5H ₂o is dissolved in respectively in deionized water and isooctanol separately, and deionized water and isooctanol volume ratio are 1:4, carries out respectively the magnetic agitation of certain hour, carries out the magnetic agitation of certain hour after two kinds of solution of gained are mixed again.This solution, as in polytetrafluoroethylene (PTFE) reactor, is carried out to the hydro-thermal reaction of a period of time at a certain temperature.By the material of preparing, through repeatedly washing, ultrasonic, centrifugal, drying operation, makes Bi ₂wO ₆flake nano material.

Tradition bismuth tungstate nano material is the clustered stacked spheroiding nano particle of sheet, and by comparison, the present invention adopts one step hydro thermal method, the bismuth tungstate nano material of preparing by adjusting solvent ratio, and this material is the nanometer sheet of disperseing.。The nanometer sheet even thickness that the present invention prepares, good dispersion.Laminated structure must expose the active crystal face of material light catalysis to greatest extent, has high visible light catalysis activity.This material also possesses selectively simultaneously, and to the absorption of different organic dyestuff, degraded has larger difference.This flake nano material preparation method is simple, with low cost, has broad application prospects at sewage treatment area.

Specifically, the advantage that technical solution of the present invention embodies is:

1, the present invention's medicine used is all bought and is obtained from market, and preparation method is simple, to equipment and experiment condition without too high requirement, easy operating.

2, the material that prepared by the present invention is nano lamellar material, has great specific area, active material light catalysis crystal face must be exposed to greatest extent simultaneously, thereby significantly improve its photocatalytic activity.

3, the product that prepared by the present invention, in having efficient photocatalysis performance, also possesses selective absorption and degradation selectivity to different dyes.As a kind of novel catalysis material, have broad application prospects in waste water control field.

Brief description of the drawings

Fig. 1 is bismuth tungstate (Bi ₂wO ₆) the SEM photo of nanometer sheet.

Fig. 2 is bismuth tungstate (Bi ₂wO ₆) part of nanometer sheet amplifies SEM photo.

Fig. 3 is bismuth tungstate (Bi ₂wO ₆) the XRD collection of illustrative plates of nanometer sheet.

Fig. 4 is bismuth tungstate (Bi ₂wO ₆) the TEM photo of nanometer sheet.

Fig. 5 is bismuth tungstate (Bi ₂wO ₆) photo of catalytic degradation rhodamine B different time sections.

Fig. 6 is bismuth tungstate (Bi ₂wO ₆) photo of catalytic degradation methylene blue different time sections.

Fig. 7 is bismuth tungstate (Bi ₂wO ₆) photo of catalytic degradation methyl orange different time sections.

Fig. 8 is bismuth tungstate (Bi ₂wO ₆) the degradation efficiency broken line graph of three kinds of dyestuffs of catalytic degradation.

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.The all raw materials that participate in reaction system in embodiment are commercially available, Na ₂wO ₄2H ₂o, Bi (NO ₃) ₃5H ₂o, isooctanol be all purchased from Solution on Chemical Reagents in Shanghai company of Chinese Medicine group, above chemical reagent be analyze pure, not purified direct use.

first step bismuth tungstate (Bi ₂ wO ₆ ) preparation and the sign of nanometer sheet

1.1 get respectively 8ml deionized water and 32ml isooctanol to conical flask, add respectively therein the Na of 164.9 milligrams ₂wO ₄2H ₂bi (the NO of O and 485.1 milligrams ₃) ₃5H ₂o, magnetic agitation 1h at ambient temperature, rotating speed is 150rpm.Fully be dissolved to evenly to solid, obtain settled solution;

1.2 mix these two parts of settled solutions, obtain suspension solution, magnetic agitation 1h at ambient temperature, and rotating speed is 150rpm;

1.3 proceed to this solution in 50mL teflon-lined autoclave, are heated to 180 DEG C in Electric heat oven, after insulation 20h, naturally cool to room temperature;

1.4 by still solution take out after, take out supernatant liquor, bottom solid sample is used respectively to deionized water and ethanol, each supersound washing twice, after by solid sample centrifugation.Then solid sample is positioned in the vacuum drying chamber of 60 DEG C, dries 4-8 hour, obtain grey powder;

The 1.5 grey sample powder that take a morsel are bonded on conducting resinl, and metal spraying is observed pattern, by field emission scanning electron microscope (Hitachi S-4800), 20,000 5000 times of multiplication factors (Fig. 1)under condition, can find out, the bismuth tungstate sample journey sheet of preparing is scattered stacking, better dispersed. adjusting enlargement ratio is 80,000 times, can be observed the structure (Fig. 2) of single nanometer sheet, nanometer sheet smooth surface, thickness is unanimous on the whole, is about 50nm.

1.6 by sample powder compacting, as for in Bruker D8 X-ray diffractometer, test, obtain X ray diffracting spectrum (Fig. 3), can find out that sample degree of crystallinity is good from diffraction peak shape.

1.7 get little power sample, ultrasonic being scattered in a small amount of ethanol, and the solution of getting 50 microlitre left and right drips on copper mesh, at room temperature allows ethanol naturally volatilize.Then use high-resolution projection microscope (TEM, JEM-2100, JEOL) to observe sample.In Fig. 4, a is the single sheet sample observing under projection Electronic Speculum.In Fig. 4, b is high-resolution sample photo, can find out that its lattice parameter is 0.315nm, and this is consistent with (113) crystal face of rhombic system.

the experiment of second step simulation Visible Light Induced Photocatalytic

Bismuth tungstate nanometer sheet sample is placed in 60 DEG C of heating 30 minutes by 2.1, makes sample have best catalytic performance.

The rhodamine B solution of 2.2 configuration 20mg/mL, gets wherein 30mL and is placed in photocatalysis instrument glass tube.

2.3 add 30mg bismuth tungstate nanometer sheet sample in glass tube, are then placed in photocatalysis instrument (Xu Jiang electrical machinery plant), use the middle pressure xenon lamp of 300W, and remove ultraviolet light with filter plate, simulate visible light catalytic condition with this.

2.4 before carrying out light-catalyzed reaction, first the solution in glass tube carried out the magnetic agitation of 1 hour in dark situation, then sampling.By the solution centrifugal taking out, retain upper strata dye solution.

2.5 by xenon lamp energising, carries out photocatalytic degradation, every sampling in 1 hour once, totally four times, then processes according to method in 2.4.

2.6 fig. 5for bismuth tungstate nanometer sheet sample catalysis rhodamine B (RhB) solution degradation, the dye solution of different time sections, can find out, dyestuff is close to and is degraded completely.

2.7 fig. 6 and Fig. 7, be under experiment condition same as described above, bismuth tungstate nanometer sheet sample catalytic degradation methylene blue (MB) and methyl orange (MO) solution, the dye solution that different time sections is extracted.

2.8 from fig. 5-7in can find out, in the present invention, the bismuth tungstate nanometer sheet of synthesized has the photocatalytic degradation effect under efficient organic dyestuff adsorption effect and visible ray.

2.9 contrast three width figure simultaneously can find out, bismuth tungstate nanometer sheet is for different organic dyestuff, and its absorption property and Photocatalytic Degradation Property have larger difference.Be embodied in, to adsorption capacity the best of methylene blue (MB), to the photocatalytic degradation best results of rhodamine B (RhB), methyl orange (MO) adsorbed and degradation effect without obvious.

2.10 Fig. 8 carry out the dye solution in Fig. 5-7 uV, visible light test(BWS003, Newark, D), degradation rate-time broken line graph of making, can more intuitively show the selective absorption catalytic performance of bismuth tungstate nanometer sheet excellence in the present invention.

Claims

1. a bismuth tungstate (Bi ₂wO ₆) preparation method of flake nano material, it is characterized in that, comprise the following steps:

According to Na ₂wO ₄2H ₂o and Bi (NO ₃) ₃5H ₂the amount of substance of O is than sampling for 1:2, by Na ₂wO ₄2H ₂o and Bi (NO ₃) ₃5H ₂o is dissolved in respectively in deionized water and isooctanol separately, and deionized water and isooctanol volume ratio are 1:4, carries out respectively the magnetic agitation of certain hour, carries out the magnetic agitation of certain hour after two kinds of solution of gained are mixed again;

This solution, as in polytetrafluoroethylene (PTFE) reactor, is carried out to the hydro-thermal reaction of a period of time at a certain temperature;

The material of preparing is through conventional washing, ultrasonic, centrifugal, dry, make Bi ₂wO ₆flake nano material.