CN103586015B

CN103586015B - Method for preparing regular-triangular-pyramid-shaped bismuth germinate visible-light catalyst

Info

Publication number: CN103586015B
Application number: CN201310591554.9A
Authority: CN
Inventors: 张高科; 万震
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2013-11-22
Filing date: 2013-11-22
Publication date: 2015-07-22
Anticipated expiration: 2033-11-22
Also published as: CN103586015A

Abstract

The invention relates to a method for preparing a regular-triangular-pyramid-shaped bismuth germinate visible-light catalyst. The method is characterized by comprising the following steps: (1) under a stirring condition, according to the mole number 12:1:350 of bismuth nitrate pentahydrate: germanium oxide: sodium hydroxide, dissolving the bismuth nitrate pentahydrate and the germanium oxide into a 5mol/L sodium hydroxide solution to obtain a mixed solution A; according to the mole number 1:0.0039 of cetyl trimethyl ammonium bromide: sodium hydroxide, adding the cetyl trimethyl ammonium bromide into the obtained mixed solution A to obtain a mixed solution B; (2) carrying out heat treatment for 12 hours at 180 DEG C in a constant temperature oven; (3) after washing for 5 times, drying for 5 hours under the condition of constant temperature of 70 DEG C to obtain the regular-triangular-pyramid-shaped bismuth germinate visible-light catalyst. The method has the advantages that the preparation process is simple and easy to operate, the used raw materials are free from pollution and low in cost, the morphology and the crystal structure of the target product particles are controllable and the like. The prepared light catalyst has better visible-light catalytic activity for organic pollutants.

Description

A kind of preparation method of positive Rhizoma Sparganii taper bismuth germanium oxide visible light catalyst

Technical field

The present invention relates to and there is visible light-responded positive Rhizoma Sparganii taper bismuth germanium oxide (Bi ₁₂geO ₂₀) preparation method of visible light catalyst, belong to photochemical catalyst new material technology and depollution of environment field.

Background technology

Photocatalysis oxidation technique, as a kind of emerging green environmental protection technique, directly can utilize sunshine, by pollutant degree of depth mineralising, does not produce secondary pollution, has broad application prospects in environmental improvement.In numerous conductor photocatalysis material, titanium dioxide (TiO ₂) because fast light corrosive power is strong, degree of stability is high, relative low price and to advantages such as human non-toxic's property, cause the concern of numerous experts and scholars.But from the utilization rate of solar energy, current TiO ₂also cannot be applied on a large scale in actual industrial water treatment, this is due to TiO ₂also there is a lot of defect, one is TiO ₂semiconductor can be with greater band gap, make it can not be excited under visible light conditions, this causes it lower to the utilization rate of solar energy; It two is TiO ₂quantum efficiency is lower, thus inhibits the photocatalytic degradation efficiency to pollutant.

In view of TiO ₂the defect of photochemical catalyst, researching and developing new and effective visible light-responded property catalysis material, is the key utilizing solar energy to realize optical catalytic environment purification, is also that practical inexorable trend and developing direction are moved towards in photocatalysis further.Research shows, some bismuth system oxides are as Bi ₂wO ₆, Bi ₂moO ₆, BiVO ₄, Bi ₁₂geO ₂₀etc. the ability with responding to visible light, can be used as visible light responsive photocatalytic material, and the Bi of wherein cubic system ₁₂geO ₂₀application prospect receive much concern.Bi ₁₂geO ₂₀photochemical catalyst is a kind of nontoxic, stable semi-conducting material.Its band gap is about 2.30-2.70eV, is greater than 420 nm to the absorption threshold value of light, and have active high, stability is strong, and the advantages such as wide spectral response, make it become the visible-light photocatalyst of current great potential.Bi ₁₂geO ₂₀preparation method have ball-milling method, sonochemical method, Czoncharlski method, chemical solution deposition and hydro-thermal method etc.Carrasco etc. adopt ball-milling method at normal temperatures with Bi ₂o ₃and GeO ₂for Bi prepared by raw material ₁₂geO ₂₀nano-powder (M.F. Carrasco, et, al. J. Mater. Sci. Lett., 2002,21,963-965).He etc. adopt chemical solution deposition with five nitric hydrate bismuths and tetraethoxy germanium for raw material, obtain through 650 ° of C roastings the Bi that average grain diameter is 40 – 60 nm ₁₂geO ₂₀nano-powder, products therefrom has good photocatalysis effect (C.H. He, et, al. Scripta Mater., 2006,54,1221 – 1225) to organic pollution methyl orange.

Research shows, the pattern of catalyst is also the key factor affecting its performance, and common pattern has spherical, shaft-like, sheet, Rhizoma Sparganii taper etc.Wherein the photochemical catalyst of positive triangular pyramid structure has the good and absorptivity comparatively advantages of higher of low-density, high-specific surface area, Surface Permeability, receives the very big concern of people.Therefore, preparation has the Bi of positive triangular pyramid structure ₁₂geO ₂₀visible light responsive photocatalyst had not only had higher scientific value but also had had the practical significance that environmental pollution administers.

Up to now, there is no that document and patent report cross with CTAB is that the hydro-thermal method of surfactant prepares positive triangular pyramid structure Bi ₁₂geO ₂₀photochemical catalyst.

Summary of the invention

The object of the present invention is to provide a kind of preparation method of positive Rhizoma Sparganii taper bismuth germanium oxide visible light catalyst, this preparation method is simple, controllability is high.

For achieving the above object, the technical solution used in the present invention is, a kind of preparation method of positive Rhizoma Sparganii taper bismuth germanium oxide visible light catalyst, is characterized in that it comprises the steps:

1) under agitation, by five nitric hydrate bismuths: germanium oxide: the molal quantity of NaOH is 12:1:350, five nitric hydrate bismuths and germanium oxide is dissolved in 5 mol/L sodium hydroxide solutions, obtains mixed liquor A; By softex kw (CTAB): the molal quantity of NaOH is 1:0.0039, adds softex kw (CTAB), obtain mixed liquid B in the mixed liquor A of gained;

2) above-mentioned mixed liquid B being transferred to liner is (volume compactedness is 75%) in the stainless steel cauldron of polytetrafluoroethylene (PTFE), and in 180 ° of C hydrothermal treatment consists 12 h in constant temperature oven, reaction naturally cools to room temperature after terminating taking-up;

3) by step 2) the product pure water that obtains and absolute ethyl alcohol respectively after centrifuge washing 5 times under the constant temperature of 70 ° of C dry 5 h, obtain positive Rhizoma Sparganii taper Bi ₁₂geO ₂₀photochemical catalyst.

The present invention adopts with softex kw (CTAB) for surfactant, and the hydro-thermal method being source metal with five nitric hydrate bismuths and germanium oxide prepares positive Rhizoma Sparganii taper Bi ₁₂geO ₂₀micro particles, Surfactant CTAB is forming the Bi of above specific morphology ₁₂geO ₂₀play an important role in micro particles.

The invention has the beneficial effects as follows: have that preparation technology is simple, with low cost, target product particle morphology and a feature such as crystal phase structure is controlled.Prepared photochemical catalyst has good visible light catalysis activity for organic pollution, effectively can increase the efficiency of light energy utilization, highly active catalysis material for this area adds one.

Utilize X-ray diffraction (XRD, D/MAX-RB), SEM (SEM, JSM-5610LV) and ultraviolet-visible spectrophotometer (UV751GD) measure the crystal structure of gained target product, surface topography and photocatalysis effect respectively.Result shows, and adopts the Bi obtained by the inventive method ₁₂geO ₂₀sample is positive Rhizoma Sparganii taper micro particles, and average grain diameter is 6-8 μm, has good photocatalysis effect.

Accompanying drawing explanation

In order to understand the present invention further, elaborate with embodiment below, and provide accompanying drawing and describe the positive Rhizoma Sparganii taper Bi that the present invention obtains ₁₂geO ₂₀micro particles, wherein:

Fig. 1 is obtained positive Rhizoma Sparganii taper Bi ₁₂geO ₂₀the XRD spectra of photochemical catalyst, wherein curve (a) and (b) are respectively the XRD spectra of embodiment 1 and embodiment 2 sample.

Fig. 2 is obtained positive Rhizoma Sparganii taper Bi ₁₂geO ₂₀the SEM photo of photochemical catalyst, wherein Fig. 2 (a) and 2 (b) are respectively the SEM photo of embodiment 1 and embodiment 2 sample.

Fig. 3 is obtained positive Rhizoma Sparganii taper Bi ₁₂geO ₂₀photochemical catalyst is to dye, rhodamine B(RhB) degradation effect figure, wherein Fig. 3 (a), 3 (b) and 3 (c) is respectively rhodamine B (RhB) solution at the photocatalytic degradation effect curve without the light degradation curve (blank assay) in catalysis situation, embodiment 1 and embodiment 2 sample.

Detailed description of the invention

Comparative example 1(does not adopt the softex kw of invention)

1) under normal temperature (25 ° of C) and magnetic agitation condition, 12 mmol five nitric hydrate bismuths and 1 mmol germanium oxide are dissolved in the 5 mol/L sodium hydroxide solutions of 70 mL;

2) liner above-mentioned mixed liquor being transferred to 100 mL is (volume compactedness is 75%) in the stainless steel cauldron of polytetrafluoroethylene (PTFE), and in 180 ° of C hydrothermal treatment consists 12 h in constant temperature oven, reaction naturally cools to room temperature after terminating taking-up;

3) by product pure water and absolute ethyl alcohol is centrifugal to wash after 5 times dry 5 h under the constant temperature of 70 ° of C respectively, positive Rhizoma Sparganii taper Bi is obtained ₁₂geO ₂₀photochemical catalyst.

This example obtain product XRD spectra see Fig. 1 (a).Fig. 1 (a) shows, obtain product XRD peak all with the cubic structure Bi of standard ₁₂geO ₂₀characteristic peak consistent, the sample synthesized by proving is pure cubic structure Bi ₁₂geO ₂₀.The SEM photo (see Fig. 2 (a)) of sample shows, products therefrom pattern is positive Rhizoma Sparganii taper, and its average grain diameter is 15-20 μm.

Product that this example obtains is used for rhodamine B degradation solution (5 mg/L), catalyst amounts is 5 g/L, adopts 300W dysprosium lamp as light source in experiment, irradiates wavelength X >=420 nm of light.Photocatalytic degradation experiment shows, after light-catalyzed reaction 4 h, compared with the blank assay (see Fig. 3 (a)) not adding catalyst, under visible light illumination, it is 31%(Fig. 3 (b) to the degradation rate of rhodamine B solution (5 mg/L) to obtained sample).

Embodiment 2

1) under normal temperature (25 ° of C) and magnetic agitation condition, 12 mmol five nitric hydrate bismuths and 1 mmol germanium oxide are dissolved in the 5 mol/L sodium hydroxide solutions of 70 mL, obtain mixed liquor A; Then in gained mixed liquor A, add 0.5 g softex kw (CTAB), obtain mixed liquid B;

2) liner above-mentioned mixed liquid B being transferred to 100 mL is (volume compactedness is 75%) in the stainless steel cauldron of polytetrafluoroethylene (PTFE), and in 180 ° of C hydrothermal treatment consists 12 h in constant temperature oven, reaction naturally cools to room temperature after terminating taking-up;

This embodiment obtain product XRD spectra see Fig. 1 (b).Fig. 1 (b) shows, its all XRD peak all with the cubic structure Bi of standard ₁₂geO ₂₀characteristic peak consistent, the sample synthesized by proving is pure cubic structure Bi ₁₂geO _20.the SEM photo (see Fig. 2 (b)) of sample shows, products therefrom pattern is positive Rhizoma Sparganii taper, and its average grain diameter is 6-8 μm.

Product that this embodiment obtains is used for rhodamine B degradation solution (5 mg/L), catalyst amounts is 5 g/L, adopts 300W dysprosium lamp as light source in experiment, irradiates the wavelength X >=420nm of light.Photocatalytic degradation experiment shows, after light-catalyzed reaction 4 h, compared with the blank assay (see Fig. 3 (a)) not adding catalyst, obtained sample under visible light illumination, it is 70%(Fig. 3 (c) to the degradation rate of rhodamine B (5mg/L)), positive Rhizoma Sparganii taper Bi prepared by the method is described ₁₂geO ₂₀photochemical catalyst has good visible light photocatalysis active.

Claims

1. a preparation method for positive Rhizoma Sparganii taper bismuth germanium oxide visible light catalyst, is characterized in that it comprises the steps:

2) above-mentioned mixed liquid B being transferred to liner is in the stainless steel cauldron of polytetrafluoroethylene (PTFE), and in 180 ° of C hydrothermal treatment consists 12 h in constant temperature oven, reaction naturally cools to room temperature after terminating taking-up;