CN111408364A

CN111408364A - Pyroelectric catalyst for treating dye sewage at room temperature under alternating cold and heat, and preparation method and application thereof

Info

Publication number: CN111408364A
Application number: CN202010198729.XA
Authority: CN
Inventors: 胡长征; 孙朝中; 季瑞; 郭晓莹; 方亮
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2020-03-20
Filing date: 2020-03-20
Publication date: 2020-07-14
Anticipated expiration: 2040-03-20
Also published as: CN111408364B

Abstract

The invention discloses a pyroelectric catalyst for treating dye sewage at room temperature under alternating cold and heat, and a preparation method and application thereof. High-purity barium carbonate, sodium carbonate, niobium pentoxide and tantalum pentoxide are mixed according to a nominal chemical formula Ba₄Na₂Nb₄Ta₆O₃₀(BNNT) burdening according to the stoichiometric ratio, carrying out the procedures of primary ball milling, drying, column pressing, presintering, secondary ball milling and the like, utilizing high-temperature solid phase reaction, and carrying out high-energy ball milling on the final product to prepare BNNT submicron powder. After cold and hot circulation is carried out for 30 times at 25-50 ℃,the degradation rate of the dye rhodamine B is more than 99 percent. The method is low in manufacturing cost, simple in preparation, suitable for large-scale industrial production, has an excellent degradation effect on dye rhodamine B, and has important significance in the aspect of treating dye sewage degradation.

Description

Pyroelectric catalyst for treating dye sewage at room temperature under alternating cold and heat, and preparation method and application thereof

Technical Field

The invention belongs to the field of sewage treatment, relates to a method for degrading dye sewage by adopting a pyroelectric catalyst, and particularly relates to a tungsten bronze structure Ba₄Na₂Nb₄Ta₆O₃₀A method for degrading rhodamine B dye sewage by using a pyroelectric catalyst.

Background

The dye is used as an important chemical raw material and is closely related to human clothes and eating habits. But a large amount of dye sewage is generated in the production and use processes of the dye, and the sewage has the characteristics of large water quantity, complex components, deep chroma, difficult degradation and the like. And most dyes have toxicity and carcinogenicity, and seriously affect the natural environment. Effective treatment of dye sewage is a difficult problem in industry development. However, the traditional biochemical treatment of dye sewage has high operation cost and more byproducts, which easily cause secondary pollution of water. Although the photocatalytic treatment degradation is a clean and green sewage treatment method, the photocatalytic efficiency is low, and the actual application of the photocatalytic treatment degradation is restricted due to insufficient response force in a dark environment. Therefore, the method for degrading the dye sewage with green color and high catalytic efficiency is of great significance.

Disclosure of Invention

The nominal chemical formula of the pyroelectric catalyst is Ba₄Na₂Nb₄Ta₆O₃₀。

In order to realize the purpose, the invention provides a method for degrading dye sewage by alternately cooling and heating at room temperature, which has high degradation efficiency, low production cost and simple treatment. The principle is that the interior of the catalyst is polarized through the change of the environmental temperature, polarization charges appear on the surface of the material macroscopically, and the charges are combined with oxygen and hydroxide ions in dye sewage to generate active particles with strong oxidizing property, so that the organic dye is oxidized and degraded, and the principle is shown in figure 1.

Based on the research, the method is applied to the specific process that 50mg of BNNT submicron powder is added into 50m L rhodamine B solution (the concentration is 5-15 mg/L), degradation is carried out under the condition of cold and hot circulation at the temperature of 25-50 ℃, circulation is carried out for 6-30 times, centrifugal separation is carried out, the ultraviolet absorbance of the dye rhodamine B before and after degradation is measured, and the degradation rate of the dye is calculated.

The invention has the following advantages: (1) the invention adopts the traditional solid phase method to prepare and uses the high-energy ball mill to prepare the BNNT submicron powder, so that the treatment cost is low, the industrial production is convenient, and the application prospect is wide. (2) The degradation condition is simple, and only room temperature cold-hot circulation is needed. And (3) the method has good decolorizing effect when being used for treating dye wastewater, and the efficiency of degrading dye rhodamine B is up to more than 99%. (4) Is environment-friendly and does not cause secondary pollution to water.

Drawings

FIG. 1 shows Ba prepared in an example of the present invention₄Na₂Nb₄Ta₆O₃₀The catalytic principle of the pyroelectric catalyst is shown schematically.

FIG. 2 shows Ba prepared according to an embodiment of the present invention₄Na₂Nb₄Ta₆O₃₀X-ray spectra of the pyroelectric catalysts.

FIG. 3 shows Ba prepared according to an embodiment of the present invention₄Na₂Nb₄Ta₆O₃₀Surface microtopography photo of pyroelectric catalyst.

FIG. 4 shows Ba prepared by an example of the present invention₄Na₂Nb₄Ta₆O₃₀Size distribution of the pyroelectric catalyst particles.

FIG. 5 shows Ba prepared according to an embodiment of the present invention₄Na₂Nb₄Ta₆O₃₀And an ultraviolet-visible absorption spectrum data graph of the 5 mg/L rhodamine B dye solution degraded by the pyroelectric catalyst after different thermal cycle times (from 25-50 ℃), wherein an inset shows a cold-heat cycle curve.

FIG. 6 shows Ba prepared according to an embodiment of the present invention₄Na₂Nb₄Ta₆O₃₀The degradation efficiency of the pyroelectric catalyst for degrading the RhB dye by thermal cycle times (25-50 ℃) is compared with that of the RhB dye degraded by thermal catalysis without BNNT.

Detailed Description

Example 1:

BaCO with the purity of 99.99 percent₃、Na₂CO₃、Nb₂O₅And Ta₂O₅The raw materials are BaCO according to the stoichiometric ratio₃:Na₂CO₃:Nb₂O₅:Ta₂O₅Putting the ingredients in a ball milling tank at a ratio of 4:1:2: 3; selecting a zirconium dioxide ball and a nylon tank; the mass of the added raw materials is 8 percent of that of the grinding ball; the mixing and ball milling time is 24 hours, the rotating speed is 180 r/min, and the ball milling medium is absolute ethyl alcohol; putting the obtained product into a drying oven at 100 ℃ for drying for 4 hours, taking out the compression column, and raising the temperature to 1000 ℃ at the heating rate of 5 ℃/min for pre-sintering for 4 hours; taking out the pre-sintered powder, grinding, ball-milling for 24 hours by taking absolute ethyl alcohol as a ball-milling medium, uniformly mixing, drying for 4 hours at 100 ℃, grinding into powder, pressing a column, raising the temperature to 1400 ℃ at the heating rate of 5 ℃/min, preserving the temperature for 10 hours in the air atmosphere of a high-temperature furnace, sintering, naturally cooling to room temperature along with the furnace, grinding the prepared sample in an agate mortar, placing the ground sample in a high-energy ball mill at the rotating speed of 300 revolutions per minute, ball-milling for 48 hours by taking absolute ethyl alcohol as a ball-milling medium, drying for 4 hours at 100 ℃, grinding into powder, thus obtaining Ba₄Na₂Nb₄Ta₆O₃₀Submicron powder.

Example 2:

BaCO with the purity of 99.99 percent₃、Na₂CO₃、Nb₂O₅And Ta₂O₅The raw materials are BaCO according to the stoichiometric ratio₃:Na₂CO₃:Nb₂O₅:Ta₂O₅Putting the ingredients in a ball milling tank at a ratio of 4:1:2: 3; selecting a zirconium dioxide ball and a nylon tank; the mass of the added raw materials is 8 percent of that of the grinding ball; the mixing and ball milling time is 24 hours, the rotating speed is 180 r/min, and the ball milling medium is absolute ethyl alcohol; putting the obtained product into an oven at 100 ℃ for drying for 4 hours, taking out the compression column, and raising the temperature to 1100 ℃ at the heating rate of 5 ℃/min for presintering for 4 hours; taking out the presintered powder, grinding, ball milling with anhydrous ethanol as ball milling medium for 24 hr, mixing, oven drying at 100 deg.C for 4 hr, grinding into powder, pressing, heating to 1550 deg.C at a heating rate of 5 deg.C/min, maintaining the temperature in air atmosphere of high temperature furnace for 4 hr, sintering, naturally cooling to room temperature,grinding the prepared sample in an agate mortar, putting the ground sample in a high-energy ball mill at the rotating speed of 350r/min, ball-milling the sample for 36 hours by taking absolute ethyl alcohol as a ball-milling medium, drying the ball-milling medium for 4 hours at the temperature of 100 ℃, and grinding the ball-milling medium into powder to obtain Ba₄Na₂Nb₄Ta₆O₃₀Submicron powder.

Example 3:

BaCO with the purity of 99.99 percent₃、Na₂CO₃、Nb₂O₅And Ta₂O₅The raw materials are BaCO according to the stoichiometric ratio₃:Na₂CO₃:Nb₂O₅:Ta₂O₅Putting the ingredients in a ball milling tank at a ratio of 4:1:2: 3; selecting a zirconium dioxide ball and a nylon tank; the mass of the added raw materials is 8 percent of that of the grinding ball; the mixing and ball milling time is 24 hours, the rotating speed is 180 r/min, and the ball milling medium is absolute ethyl alcohol; putting the obtained product into a drying oven at 100 ℃ for drying for 4 hours, taking out the compression column, and raising the temperature to 1200 ℃ at the heating rate of 5 ℃/min for pre-sintering for 4 hours; taking out the pre-sintered powder, grinding, ball-milling for 24 hours by taking absolute ethyl alcohol as a ball-milling medium, uniformly mixing, drying for 4 hours at 100 ℃, grinding into powder, pressing a column, raising the temperature to 1500 ℃ at the heating rate of 5 ℃/min, preserving the heat for 6 hours in the air atmosphere of a high-temperature furnace, sintering, naturally cooling to room temperature along with the furnace, grinding the prepared sample in an agate mortar, placing the ground sample in a high-energy ball mill at the rotating speed of 350 revolutions per minute, ball-milling for 24 hours by taking absolute ethyl alcohol as a ball-milling medium, drying for 4 hours at 100 ℃, grinding into powder, thus obtaining Ba₄Na₂Nb₄Ta₆O₃₀Submicron powder. XRD powder diffraction analysis of the powder was carried out, as shown in FIG. 2, confirming Ba₄Na₂Nb₄Ta₆O₃₀The submicron powder has good crystallinity, is a pure-phase tetragonal tungsten bronze structure, and does not generate a second phase. FIGS. 3 and 4 show the surface microscopic morphology of BNNT and the particle size distribution of the powder particles, and the results show that the particle size of BNNT powder is 60-550 nm and the average particle size is 179 nm. Indicating that the size of the BNNT catalyst powder is submicron.

Adding 50mg BNNT submicron powder into 50m L5 mStirring the rhodamine B solution of g/L in a dark environment for one hour to achieve adsorption-desorption balance between the rhodamine B dye and a BNNT catalyst, then taking 3m L rhodamine B solution after every 6 times of circulation under the cold-hot circulation of 25-50 ℃, taking supernatant after centrifugal separation, measuring the absorption peak intensity by an ultraviolet-visible spectrophotometer, and finally obtaining the formula D (A)₀-A_t)/A₀× 100 percent calculation of degradation rate of dye rhodamine B D. figure 5 is a final rhodamine B ultraviolet absorption spectrum data chart, and the degradation rate of BNNT submicron powder to dye rhodamine B reaches 99 percent after 30 times of cold-hot circulation at 25-50 ℃ through calculation, figure 6 is a data chart added with submicron powder Ba₄Na₂Nb₄Ta₆O₃₀A comparative graph of the degradation efficiency of the RhB dye degraded by thermal cycle times (25-50 ℃) and the RhB dye degraded by directly carrying out cold-heat exchange without BNNT submicron powder. Indicating Ba₄Na₂Nb₄Ta₆O₃₀The submicron powder has a key function in the degradation process.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.

Claims

1. A pyroelectric catalyst for treating dye sewage at room temperature by alternating cold and heat is characterized in that the nominal chemical formula of the pyroelectric catalyst is Ba₄Na₂Nb₄Ta₆O₃₀。

2. The preparation method of the pyroelectric catalyst according to claim 1, characterized by comprising the following specific steps:

(1) BaCO with purity of more than 99.9 percent₃、Na₂CO₃、Nb₂O₅And Ta₂O₅As starting material, according to BaCO₃:Na₂CO₃:Nb₂O₅:Ta₂O₅Mixing the materials according to the molar ratio of 4:1:2:3, then using absolute ethyl alcohol as a ball milling medium, mixing and ball milling for 24 hours, and finally obtaining the productDrying for 4 hours at 100 ℃ to prepare a dried sample;

(2) pre-sintering the dried sample prepared in the step (1) at 1000-1200 ℃ for 4 hours to prepare a pre-sintered column body;

(3) putting the pre-sintered column body prepared in the step (2) into an agate mortar to be ground into powder, then using absolute ethyl alcohol as a ball milling medium to perform ball milling for 24 hours, uniformly mixing, drying for 4 hours at 100 ℃, then grinding into powder, pressing the column, sintering for 4-10 hours at 1400-1550 ℃ in the air atmosphere of a high-temperature furnace, then naturally cooling to room temperature along with the furnace, finally grinding the sample into powder, putting the sample into a high-energy ball mill, using absolute ethyl alcohol as a ball milling medium to perform ball milling for 24 hours, drying for 4 hours at 100 ℃, and then grinding into powder, thus obtaining Ba₄Na₂Nb₄Ta₆O₃₀The catalyst powder of (3).

3. The preparation method according to claim 2, wherein the pyroelectric catalyst is prepared from high-purity barium carbonate, sodium carbonate, niobium pentoxide and tantalum pentoxide.

4. Ba of claim 2₄Na₂Nb₄Ta₆O₃₀The preparation method of the pyroelectric catalyst is characterized in that Ba is prepared₄Na₂Nb₄Ta₆O₃₀The catalyst powder is prepared by ball milling zirconium dioxide with a ball diameter of 0.5mm and anhydrous ethanol as a ball milling medium for 24-48 h in a zirconium dioxide ceramic ball milling tank at a rotating speed of 300-350 r/min.

5. The pyroelectric catalyst of claim 1 is used for degrading rhodamine B dye sewage.

6. Use of the pyroelectric catalyst according to claim 5, characterized in that: the catalyst is used for degrading dye rhodamine B under the cold-hot circulation at 25-50 ℃, and the catalytic efficiency is 99%.