CN101786006A

CN101786006A - Preparation method of bismuth oxybromide photocatalyst

Info

Publication number: CN101786006A
Application number: CN 201010141878
Authority: CN
Inventors: 方艳芬; 程根伟; 鲁旭阳; 范继辉
Original assignee: Institute of Mountain Hazards and Environment IMHE of CAS
Current assignee: Institute of Mountain Hazards and Environment IMHE of CAS
Priority date: 2010-04-08
Filing date: 2010-04-08
Publication date: 2010-07-28
Anticipated expiration: 2030-04-08
Also published as: CN101786006B

Abstract

A preparation method of bismuth oxybromide with high-efficient visible light activities adopts cetyl pyridine bromide as raw material, the surfactant has the functions of providing bromine source and structure template agent simultaneously, and the bismuth oxybromide with stable structure and performance and high activity can be obtained. Dilute nitric acid solution dissolved with Bi(NO3)3 is dripped into the cetyl pyridine bromide solution to produce faint yellow precipitate, and then the pH value needs to be adjusted to 7; and the mass ratio of the two raw materials meets nBi: nBr=1: 1.5. The bismuth oxybromide synthesized by the method is faint yellow solid powder and has no special smell. The bismuth oxybromide has quadrangular crystal form detected by an instrument, the specific surface area is large, the surface aperture is small, the band gap is 2.62eV, the crystallinity is 98.3% of layer crystal, the product purity is more than 99.9%, the visible light activity of the prepared bismuth oxybromide is high, and various organic dyes and microcystic toxins can be degraded effectively in a short time.

Description

A kind of preparation method of bismuth oxybromide photocatalyst

Technical field

The present invention relates to a kind of degraded toxic organic pollutant function Preparation of catalysts method that has, be specifically related to a kind of preparation method of bismuth oxybromide photocatalyst.

Background technology

The tradition nano titanium oxide is represented the multiple poisonous organic pollution of can degrading efficiently as the typical case of efficient oxidation technology always.But must use the application bottleneck of ultraviolet light as light source owing to there is, seeking a kind of novel photochemical catalyst that can directly absorb visible light at present is new thinking.Bismuth oxybromide (BiOBr) has unique Open architecture and the simultaneous structure of indirect transition pattern, and the effective separation and the electric charge that help hole-duplet shift, so this catalyst possesses very high visible light photocatalysis active.Adopt surfactant bromohexadecane yl pyridines to come synthetic bromide bismuth oxide (BiOBr) not appear in the newspapers.

Summary of the invention

The objective of the invention is to provide a kind of employing surfactant bromohexadecane yl pyridines to come the synthetic bromide bismuth oxide, thereby obtain a kind of preparation method who possesses the bismuth oxybromide of efficient visible light activity.

The object of the present invention is achieved like this: a kind of preparation method of bismuth oxybromide photocatalyst under 30-50 ℃ of temperature, will be dissolved with Bi (NO ₃) ₃Dilute nitric acid solution, be added drop-wise in surfactant bromohexadecane yl pyridines (CPB) solution, the amount of substance ratio of two raw materials satisfies nBi: nBr=1: 1.5, regulate the pH to 7 of mixed liquor again with alkali lye, put into reactor in 160-180 ℃ of heating, material after heating finishes obtains powdered substance through centrifugal filtration, will obtain bismuth oxybromide photocatalyst behind the resulting powdered substance cleaning, drying.The alkali lye that is used to regulate the pH of mixed value is sodium hydroxide solution.

Described concentration of sodium hydroxide solution is 6mol/L.

The time that solution after the adjusting pH value heats in reactor is 13-20h.

Bi (NO ₃) ₃6H ₂The O pressed powder is dissolved in and obtains being dissolved with Bi (NO in the dilute nitric acid solution ₃) ₃Dilute nitric acid solution.

The preparation method of bismuth oxybromide photocatalyst provided by the invention, adopt the bromohexadecane yl pyridines as raw material, compare with traditional bromine source such as cetyl ammonium bromide or sodium bromide, this surfactant exists stable pyridine ring structure, this will help preparing the bismuth oxybromide that possesses stable laminated structure, architectural characteristics such as the degree of crystallinity of raising bismuth oxybromide, specific area etc., the visible light activity of bismuth oxybromide is greatly improved, under visible light, dyeing waste water and Microcystin is all had degrading activity efficiently.

The bismuth oxybromide that possesses the efficient visible light activity by the present invention obtains has following advantage:

(1) bismuth oxybromide possesses stable layer structure, the big (12.03m of specific area ²g ^-1), the degree of crystallinity height can reach 98.2%, is pure positive cubic type crystal, and its energy gap is 2.62eV, but absorbing wavelength is greater than the visible light of 473nm;

(2) visible light activity height, efficient degradation organic dyestuff and Microcystin at short notice, under radiation of visible light (in the 220min of λ 〉=420nm), the degradation rate that for concentration is the microcapsule phycotoxin MC-LR of 3mg/L can reach 100%, and adopts the synthetic degradation efficiency of bismuth oxybromide under the visible light condition of raw materials such as cetyl ammonium bromide or sodium bromide scarcely desirable.

(3) preparation method is simple, mild condition, handling safety;

But bismuth oxybromide is the efficient degradation dyeing waste water under the visible light condition, is example with all types of dyestuffs of degrading:

Concrete response parameter is as follows: catalyst amount is 0.4g/L; PH is 3.0; Reaction temperature is a room temperature; Light source be visible light (λ 〉=420nm, Eav=25000Lux); Reaction time is 30min and 90min.Select all kinds dyestuff with and degradation efficiency see following table for details:

The detection method of dyestuff residual concentration is: certain reaction time sampling 4mL is in the 5mL centrifuge tube, in the centrifugal 10min of 10000 commentaries on classics/min, use ultraviolet-uisible spectrophotometer to measure its absorbance A in the maximum absorption wave strong point of dyestuff, (λ=566nm), the absorbance that obtains has been expressed its degradation efficiency at 566nm as the maximum absorption wavelength of dyestuff acid brilliant pink SRB; Utilize total organic carbon (TOC) analyzer to measure total organic carbon TOC value, it has expressed the mineralization rate to substrate.

With absorbance A under the differential responses time and reaction initial absorbance A ₀Ratio (A/A ₀) with time mapping, the kinetic curve of each dyestuff that obtains degrading, the expression bismuth oxybromide is to the degradation efficiency of different dyes, as shown in Figure 1;

As shown in Figure 1 bismuth oxybromide can efficient degradation under the visible light condition various types of dyestuff acid brilliant pink SRB, when irradiation 90min, degradation rate to SRB can reach 99%, is 86% to the degradation rate of RhB, also can degrade 14% at 90min to the azo dyes of difficult degradation.

Utilize TOC value and the initial TOC of reaction under the reaction time ₀Ratio (TOC/TOC between the value ₀) map with the time, obtain the mineralising effect curve, as shown in Figure 2.

As shown in Figure 2, as we can see from the figure, the radiation of visible light BiOBr of process 120min just can reach 63.3% to the mineralization rate of RhB

Bismuth oxybromide is efficient degradation algae toxin under the visible light condition, is example with the microcapsule phycotoxin MC-LR:

Concrete response parameter is as follows: the microcapsule phycotoxin MC-LR initial concentration is 3.0mg/L; Catalyst amount is 10mg/L; Reaction temperature is a room temperature; Light source be visible light (λ 〉=420nm, Eav=25000Lux) and long wave ultraviolet light (UVA); Reaction time is 240min.

The detection method of microcapsule phycotoxin MC-LR residual concentration: certain hour certain reaction time sampling 0.5mL is in the 1.5mL centrifuge tube at interval, and the centrifugal 15min of 15000 commentaries on classics/min measures MC-LR concentration by high-efficient liquid phase analysis.Analysis condition is as follows: chromatographic column is Kromasil 100 C18,250mm * 4.6mm, 5 μ m; Flowing is methyl alcohol mutually: 0.05% trifluoroacetic acid aqueous solution=65: 35; Flow velocity is 0.6m L/min; It is 238nm that ultraviolet detects wavelength; Sample size is 20 μ L; The MC-LR appearance time is at 12.5min.

Microcapsule phycotoxin MC-LR according to the differential responses time goes out peak area S and reacts initial MC-LR to go out peak area S ₀Ratio and reaction time mapping obtain the degradation kinetics curve, as shown in Figure 3.

As shown in Figure 3, the bismuth oxybromide photocatalyst of preparation can efficient degradation noxious material Microcystin under the visible light condition.Do not adding under the catalyst condition, simple visible light, λ 〉=420nm without any degradation, after dropping into bismuth oxybromide, only reacts 220min to the algae toxin, and bismuth oxybromide is that the degradation rate of the microcapsule phycotoxin MC-LR of 3mg/L just reaches 100% to concentration; Do not adding under the catalyst condition, under the simple long wave ultraviolet light, UV-365nm only brings 0.9% degraded to the algae toxin, after dropping into bismuth oxybromide, only passes through the irradiation of 60min, and bismuth oxybromide just reaches 100% to the degradation rate of algae toxin.

Description of drawings

Fig. 1 is the degrade kinetic curve of dissimilar dyestuffs of the bismuth oxybromide that synthesizes;

Fig. 2 is the bismuth oxybromide that the synthesizes mineralising curve to acid brilliant pink SRB;

The bismuth oxybromide that Fig. 3 synthesizes under visible light and long wave ultraviolet light condition to the degradation kinetics curve of microcapsule phycotoxin MC-LR;

Fig. 4 for raw material adopts different bismuth bromine contents than (nBi: the nBr) kinetic curve of prepared bismuth oxybromide degraded acid brilliant pink;

Fig. 5 is the kinetic curve of the bismuth oxybromide degraded acid brilliant pink of preparation under the condition of different pH;

Fig. 6 is dyestuff acid brilliant pink (SRB) structure chart;

Fig. 7 is the microcapsule phycotoxin MC-LR structure chart;

Fig. 8 is XRD (x-ray powder diffraction instrument) figure of the BiOBr that obtains of the present invention;

Fig. 9 is the reflection ultra-violet absorption spectrum of the BiOBr that obtains of the present invention;

Figure 10 is the sem photograph of the BiOBr that obtains of the present invention.

The specific embodiment

Embodiment:

The bismuth oxybromide that the present invention obtains is to adopt the bromohexadecane yl pyridines as raw material, with Bi (NO ₃) ₃6H ₂The O pressed powder is dissolved in and obtains being dissolved with Bi (NO in the dilute nitric acid solution ₃) ₃Dilute nitric acid solution, again with Bi (NO3) ₃6H ₂After the O drips of solution is added in the bromohexadecane yl pyridines solution, need to regulate pH to 7; The amount of substance ratio of two raw materials satisfies nBi: nBr=1: 1.5.

Fig. 1 has expressed the degrade kinetic curve of all types of dyestuffs of bismuth oxybromide, and as can be seen from the figure, bismuth oxybromide all has in various degree degraded to all types of dyestuffs, and this catalyst of surface possesses the efficient degradation effect to dyeing waste water;

Fig. 2 expressed bismuth oxybromide can be at short notice effective mineralising dyestuff acid brilliant pink SRB;

Fig. 3 has expressed and present best titanium dioxide (P ₂O ₅) photochemical catalyst compares, the bismuth oxybromide algae toxin of all degrading at high speed under visible light and long wave ultraviolet light;

Fig. 4 has expressed as bismuth bromine content ratio, i.e. nBi: nBr=1: bismuth oxybromide possessed best degradation efficiency in 1.5 o'clock;

Fig. 5 has expressed when pH is neutrallty condition, and bismuth oxybromide possesses best degradation efficiency.

Bismuth oxybromide is the faint yellow solid powder, no special odor.Its crystal formation of instrument detecting is positive tetragonal structure, and specific area is 12.03m ²g ^-1, surface apertures is little, and total pore volume is 0.13cm ³/ g, its energy gap is 2.62eV, and degree of crystallinity is 98.3% layered crystal, and product purity is greater than 99.9%.

The preparation method of bismuth oxybromide:

1.152g bromohexadecane yl pyridines (CPB) solution is dissolved in the 60mL water, is mixed with the CPB solution of 19.2mg/mL, obtain under 40 ℃ of water bath condition, taking by weighing Bi (NO ₃) ₃6H ₂O is dissolved in 15mL1.2mol/L HNO ₃In, it slowly is added drop-wise in the surfactant bromohexadecane yl pyridines solution that mixes, the amount of substance that satisfies bismuth ion and bromide ion is than being nBi: nBr=1: 1.5, produce a large amount of faint yellow precipitations in the dropping process, then use the 6mol/LNaOH regulator solution to required pH7, continue to stir 1h afterwards, pour in the reactor then, in 160-180 ℃ of reaction 14-19h, suction filtration sample and with distilled water washing three times is milled after 50 ℃ of oven dry under air conditions and can be obtained bismuth oxybromide photocatalyst.

Claims

1. the preparation method of a bismuth oxybromide photocatalyst is characterized in that: under 30-50 ℃ of temperature, will be dissolved with Bi (NO ₃) ₃Dilute nitric acid solution, be added drop-wise in surfactant bromohexadecane yl pyridines (CPB) solution, the amount of substance ratio of two raw materials satisfies nBi: nBr=1: 1.5, regulate the pH to 7 of mixed liquor again with alkali lye, put into reactor in 160-180 ℃ of heating, material after heating finishes obtains powdered substance through centrifugal filtration, will obtain bismuth oxybromide photocatalyst behind the resulting powdered substance cleaning, drying.

2. the method for preparation method's bismuth oxybromide of a kind of bismuth oxybromide photocatalyst according to claim 1 is characterized in that: the alkali lye that is used to regulate the pH of mixed value is sodium hydroxide solution.

3. the method for preparation method's bismuth oxybromide of a kind of bismuth oxybromide photocatalyst according to claim 2, it is characterized in that: described concentration of sodium hydroxide solution is 6mol/L.

4. the method for preparation method's bismuth oxybromide of a kind of bismuth oxybromide photocatalyst according to claim 1 is characterized in that: regulating the time that the solution after the pH value heats in reactor is 13-20h.

5. the method for preparation method's bismuth oxybromide of a kind of bismuth oxybromide photocatalyst according to claim 1 is characterized in that: with Bi (NO ₃) ₃6H ₂The O pressed powder is dissolved in and obtains being dissolved with Bi (NO in the dilute nitric acid solution ₃) ₃Dilute nitric acid solution.