CN110015691B

CN110015691B - Method for preparing nano-scale barium molybdate particles

Info

Publication number: CN110015691B
Application number: CN201910445944.2A
Authority: CN
Inventors: 柴金岭; 宋苗苗
Original assignee: Shandong Normal University
Current assignee: Shandong Normal University
Priority date: 2019-05-27
Filing date: 2019-05-27
Publication date: 2021-10-01
Anticipated expiration: 2039-05-27
Also published as: CN110015691A

Abstract

The invention relates to a method for preparing nano barium molybdate particles, which takes W/O microemulsion consisting of diethyl malonate, ethanol and water as a template and adopts a double microemulsion method to synthesize nano barium molybdate. Firstly, constructing a diethyl malonate/ethanol/water microemulsion system; then respectively preparing barium salt and molybdate microemulsion, and mixing the aqueous solution of barium salt with diethyl malonate and ethanol to obtain barium salt W/O microemulsion; mixing the aqueous solution of molybdate with diethyl malonate and ethanol to obtain W/O microemulsion of molybdate; the nano-scale barium molybdate particles with different particle sizes are obtained by controlling the reaction conditions.

Description

Method for preparing nano-scale barium molybdate particles

Technical Field

The invention belongs to the technical field of nano material preparation, and particularly relates to a method for preparing nano barium molybdate particles.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Recently, the preparation of nano-scale molybdates has received attention. Because of the unique structure and the luminescent property, the material can be used for fluorescent powder, optical fiber, pigment, ion conductor and the like. Of the numerous molybdate products, BaMoO with scheelite structure₄The material has green light emitting characteristic and special photoelectric application prospect, and thus becomes an important material in the photoelectric field.

It is well known that nanoparticles have many characteristic properties compared to large-sized particles because of their small size. Such as surface effects, small-scale effects, quantum-size effects, macroscopic quantum tunneling effects, and the like. The properties of the nanoparticles are related to the composition, size, structure, morphology and the like of the nanoparticles, and also determine the application prospects of the nanoparticles in the fields of optics, electricity, chemical catalysis, biology and the like.

The preparation of nano-micron inorganic materials with special size and morphology has important significance for the development of material chemistry and the development of effective nanoparticle preparation technology, so that the controllable synthesis of nano structures is always a research hotspot in the field of nano technology. Recently, there has been an increasing interest in the controlled synthesis of polyhedral nanoparticles. The preparation method of the nano-particles is commonly a gas phase precipitation method,precipitation methods, sol-gel methods, hydrothermal synthesis methods, and microemulsion synthesis methods. Most of the preparation methods have the defects of complex preparation process, complicated process, higher cost and the like. BaMoO₄The preparation of the BaMoO is generally carried out by adopting a solid-phase reaction, and in recent years, the BaMoO with nanometer or micrometer scale is prepared by adopting a W/O microemulsion method₄And (4) crystals. The inventor finds that the particle size of the generated nano barium molybdate cannot be controlled by the conventional W/O microemulsion method.

Disclosure of Invention

In view of the above problems occurring in the prior art, it is an object of the present invention to provide a method for preparing nano-sized barium molybdate particles. The invention relates to a method for synthesizing a nano material by constructing surfactant-free microemulsion by a diethyl malonate/ethanol/water ternary mixed system and by means of a unique structure of a W/O area. The method aims to exert the application value of the surfactant-free method and avoid the defects of the existence of the surfactant on the preparation of the nano material; secondly, the size of the synthetic material can be controlled by regulating and controlling the reaction temperature and the reaction time; thirdly, the BaMoO with good structure and appearance and higher application value is synthesized by the method₄And (3) nanoparticles.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a method for preparing nano barium molybdate particles takes W/O microemulsion consisting of diethyl malonate, ethanol and water as a template, and adopts a double microemulsion method to synthesize nano barium molybdate.

The invention uses the W/O microemulsion composed of diethyl malonate, ethanol and water as a template, the W/O phase area range in the formed ternary phase diagram is larger, and the beneficial effects are as follows: on one hand, the range of each reactant for preparing the nano barium molybdate can be enlarged, on the other hand, the particle size of the prepared nano barium molybdate can be adjusted, and the nano barium molybdate with different particle sizes can be obtained by adjusting the reaction time and the reaction temperature in the W/O phase region range of the microemulsion system, so that the adjustment of the particle size of the nano barium molybdate is realized. The method comprises the following specific steps:

constructing a diethyl malonate/ethanol/water microemulsion system;

mixing the aqueous solution of barium chloride with diethyl malonate and ethanol to obtain W/O microemulsion of barium chloride;

mixing the aqueous solution of sodium molybdate with diethyl malonate and ethanol to obtain W/O microemulsion of sodium molybdate;

and dropwise adding the W/O microemulsion of barium chloride into the W/O microemulsion of sodium molybdate to react to obtain a product, and washing and drying the product to obtain the nano barium molybdate.

The synthesis principle is as follows: firstly, diethyl malonate, ethanol and MoO-containing solution are utilized₄ ²⁺Aqueous solution or Ba²⁺Preparing W/O microemulsion without surfactant from water solution, mixing two microemulsions containing different ions, and mixing Ba²⁺With MoO₄ ²⁺Rapid binding to BaMoO₄White precipitate. When BaMoO is in solution₄After the particles are generated, the particles are controlled by the droplet structure of the W/O microemulsion and gradually grow in the droplets, and the particle size of the finally generated material is nano-scale.

In some embodiments, Na₂MoO₄Microemulsion and BaCl₂The mass ratio of the ethanol to the diethyl malonate to the water in the microemulsion is equal.

Two microemulsions with the same mass ratio are both W/O structures in order to ensure that the two microemulsions have the same structure.

Preferably, in the W/O microemulsion of the barium salt, the mass ratio of the barium salt aqueous solution to the ethanol to the diethyl malonate is 3.0:7.0: 9.2; preferably, in a W/O microemulsion of molybdate, Na₂MO₄The mass ratio of the aqueous solution, ethanol and diethyl malonate is 3.0:7.0: 9.2.

In some embodiments, BaCl₂And Na₂MoO₄The concentration of (B) was the same as 0.025 mol/L.

In some embodiments, Na₂MoO₄Microemulsion and BaCl₂The microemulsion reaction is carried out directly at room temperature; preferably, the reaction time at room temperature is 90-110h, 10-14h or 22-26 h.

In some embodiments, Na₂MoO₄Microemulsion and BaCl₂The microemulsion reaction conditions are that hydrothermal reaction is carried out after mixing at room temperature, the temperature of the hydrothermal reaction is 150-170 ℃, and the time of the hydrothermal reaction is 10-14 h.

The particle size and morphology of the nano barium molybdate obtained by different reaction temperatures and reaction times are different, and the properties of the barium molybdate material have certain difference, so that the obtained nano barium molybdate is more widely applied.

In some embodiments, the barium molybdate nanomaterial is washed by sequentially washing with deionized water and ethanol. And washing the nano barium molybdate to remove impurity ions.

In some embodiments, the drying method is drying for 10-14h in an oven at 50-70 ℃.

The barium molybdate nano material prepared by the method.

In some embodiments, the barium molybdate nanomaterial has a particle size of 50-200 nm.

The barium molybdate nano material is applied to the preparation of an electronic luminescent material.

The invention has the beneficial effects that:

compared with the traditional microemulsion method, the method utilizes diethyl malonate, ethanol and water to construct the W/O microemulsion, and is simple and convenient in preparation method and low in preparation cost because the method does not contain a surfactant, and all solvents are almost harmless to human bodies and the environment, so that the method accords with the green chemical concept. The reaction time is controllable, and the size of the obtained nano material can be directly controlled;

compared with the method for preparing nano barium molybdate by microemulsion in the prior art, the microemulsion system has larger W/O phase region, so the proportion range of diethyl malonate, ethanol and water is larger, and the range of the diethyl malonate, the ethanol and the water is adjustable, so the formed W/O microemulsion is easier and more stable (compared with the method for preparing nano barium molybdate by microemulsion in the prior art, the microemulsion system adopts a new ester substance, namely diethyl malonate, to form microemulsion with water and ethanol). And the W/O microemulsion system formed by diethyl malonate can be regulated and controlled to prepare barium molybdate with different nano particle sizes by regulating and controlling the temperature and the reaction time.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the invention and not to limit the invention.

FIG. 1 is a ternary phase diagram of diethyl malonate, ethanol and water according to example 1, wherein the contents of the system components are mass contents. Two regions can be seen in fig. 1, one being a multiphase region (shaded in the figure). Second is a single phase region (blank portion in the figure). Wherein I in the single-phase region represents O/W microemulsion, II represents W/O microemulsion, III represents B.C. type microemulsion, and the synthesis of nano material is carried out in the W/O microemulsion of the single-phase region.

FIG. 2 is an X-ray diffraction pattern of 50nm, 100nm and 200nm barium molybdate nanoparticles obtained in examples 2 to 4.

FIG. 3 is an X-ray diffraction pattern of barium molybdate nanoparticles having a diameter of 50nm obtained in example 2 after a reaction time of 100 hours at 25 ℃.

FIG. 4 is a SEM photograph of the barium molybdate nanoparticles of example 2 having a diameter of 50nm obtained after a reaction time of 100h at 25 ℃.

FIG. 5 is a transmission electron micrograph of barium molybdate nanoparticles having a diameter of 50nm obtained after reaction of example 2 at 25 ℃ for 100 hours.

FIG. 6 is an X-ray diffraction pattern of barium molybdate nanoparticles having a diameter of 100nm obtained in example 3 after 24 hours of reaction at 160 ℃.

FIG. 7 is a SEM image of the barium molybdate nanoparticles of 100nm in diameter obtained in example 3 after 24h reaction at 160 ℃.

FIG. 8 is a TEM image of barium molybdate nanoparticles having a diameter of 100nm obtained in example 3 after a reaction time of 24 hours at 160 ℃.

FIG. 9 is an X-ray diffraction pattern of barium molybdate nanoparticles having a diameter of 200nm obtained in example 4 after 12 hours of reaction at 160 ℃.

FIG. 10 is a SEM photograph of barium molybdate nanoparticles 200nm in diameter obtained in example 4 after 12h reaction at 160 ℃.

FIG. 11 is a transmission electron micrograph of barium molybdate nanoparticles having a diameter of 200nm obtained after 12 hours of reaction at 160 ℃ in example 4.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise. The invention will be further illustrated by the following examples

Example 1

Constructing a diethyl malonate/ethanol/water surfactant-free microemulsion system:

weighing diethyl malonate and water in a dry and clean test tube according to the mass ratio of 9:1, 8:2, 7:3, 6:4, 5:5, 4:6 and 3: 7. 1.0g of the binary mixture of 2:8 and 1:9, and then placing the test tube into a constant-temperature water bath kettle to keep the constant temperature, wherein the temperature of the water bath kettle is kept at 25 +/-0.2 ℃. Under magnetic stirring, ethanol is dripped into the mixed liquid in the test tube dropwise, and the mixed liquid becomes clear gradually from turbidity. The mass of ethanol added at clarification was recorded. This operation was repeated three times and the average of the ethanol mass was plotted. The mass of ethanol added into each test tube is as follows: 0.1811g, 0.283g, 0.3396g, 0.3679g, 0.4104g, 0.4245g, 0.4104g, 0.4273g and 0.3651 g. A ternary phase diagram is drawn as shown in figure 1.

Partitioning of microemulsion systems of different structures in the single-phase region:

dividing the structure of a surfactant-free microemulsion single-phase region by means of an electric conduction method: adding clean and dry test tubes into the test tubes according to the mass ratio: ultrapure water (18.25 M.OMEGA.. multidot.cm) in a ratio of 1:9, 2:8, 3:7, 4:6 and 5:5 and ethanol, the total mass of the ultrapure water and the ethanol being fixed to 4 g. Diethyl malonate is gradually added under magnetic stirring, the test tube is placed in a water bath kettle at the temperature of 25 +/-0.2 ℃ for six minutes at constant temperature, and the conductivity value of the mixed solution is measured by using a conductivity meter DJS-0.1 type electrode. Three microstructures of O/W, B.C. and W/O are marked according to a change curve of the conductivity value along with the increase of the diethyl malonate content (as shown in figure 1).

Example 2

50nm BaMoO₄The preparation method of the nano-particles comprises the following steps:

(1) 0.025mol/L of Na is prepared₂MoO₄The aqueous solution was mixed with 7.0g of ethanol and 9.2g of diethyl malonate weighed on an analytical balance, and 3g of Na was gradually added under stirring₂MoO₄An aqueous solution. Stirring at room temperature for 30min to obtain a mixture containing MoO₄ ^2-W/O microemulsion of (1).

(2) 0.025mol/L BaCl is prepared₂The aqueous solution was mixed with 7.0g of ethanol and 9.2g of diethyl malonate weighed on an analytical balance, and 3.0g of BaCl was gradually added with stirring₂An aqueous solution. Stirring at room temperature for 30min to obtain Ba-containing powder²⁺W/O microemulsion of (1).

(3) The Ba content obtained in the step (2)²⁺The W/O microemulsion is added into the MoO-containing solution obtained in the step (1) dropwise under the magnetic stirring₄ ^2-The W/O microemulsion of (1) is magnetically stirred for 100 hours to form milky mixed solution while keeping the reaction temperature at about 25 ℃. And then, centrifugally separating all the mixed solution, washing the mixed solution twice by using deionized water and ethanol, and then placing the washed mixed solution in an oven at 60 ℃ for 12 hours for drying to be tested. The X-ray diffraction patterns of the obtained 50nm nano barium molybdate are shown in FIGS. 2 and 3, and 1 at the upper right corner of FIG. 3 represents 50 nm. FIG. 4 shows a scanning electron micrograph of the 50nm barium molybdate nanoparticles by field emission scanning, and FIG. 5 shows a transmission electron micrograph of the 50nm barium molybdate nanoparticles by transmission scanning, showing that the shape of the 50nm barium molybdate particles is spheroidal as shown in FIGS. 4 and 5.

Example 3

100nm BaMoO₄The preparation method of the nano-particles comprises the following steps:

(1) 0.025mol/L of Na is prepared₂MoO₄The aqueous solution was mixed with 7.0g of ethanol and 9.2g of diethyl malonate weighed on an analytical balance, and 3.0g of Na was gradually added under stirring₂MoO₄An aqueous solution. Stirring at room temperature for 30min to obtain a mixture containing MoO₄ ^2-W/O microemulsion of (1).

(2) 0.025mol/L BaCl is prepared₂The aqueous solution was mixed with 7.0g of ethanol and 9.2g of diethyl malonate weighed on an analytical balance, and 3g of BaCl was gradually added under stirring₂An aqueous solution. Stirring at room temperature for 30min to obtain Ba-containing powder²⁺W/O microemulsion of (1).

(3) The Ba content obtained in the step (2)²⁺The W/O microemulsion is added into the MoO-containing solution obtained in the step (1) dropwise under the magnetic stirring₄ ^2-In the W/O microemulsion, the reaction temperature is fixed at about 25 ℃, and magnetic stirring is kept for 5min to form milky mixed solution; then transferring the mixed solution into a polytetrafluoroethylene reaction kettle, and reacting for 24 hours at 160 ℃; and naturally cooling to room temperature, taking all samples, centrifugally separating, washing with deionized water and ethanol twice respectively, and then placing in an oven at 60 ℃ for 12h for drying to be tested.

An appropriate sample was taken for X-ray diffraction detection (XRD) as shown in FIGS. 2 and 6, and 2 at the upper right corner of FIG. 6 represents 100 nm. As shown in fig. 7, which is a field emission electron microscope (SEM) picture, and fig. 8, which is a Transmission Electron Microscope (TEM) picture, it is clear from fig. 7 and 8 that the shape of 100nm barium molybdate is spheroidal.

Example 4

200nm BaMoO₄The preparation method of the nano-particles comprises the following steps:

(2) 0.025mol/L BaCl is prepared₂Aqueous solution, using analytical balance7.0g of ethanol and 9.2g of diethyl malonate were weighed and mixed, and 3.0g of BaCl was gradually added under stirring₂An aqueous solution. Stirring at room temperature for 30min to obtain Ba-containing powder²⁺W/O microemulsion of (1).

(3) The Ba content obtained in the step (2)²⁺The W/O microemulsion is added into the MoO-containing solution obtained in the step (1) dropwise under the magnetic stirring₄ ^2-In the W/O microemulsion, the reaction temperature is controlled to be about 25 ℃, and magnetic stirring is kept for 5min to form milky mixed solution; then transferring the mixed solution into a polytetrafluoroethylene reaction kettle, and reacting for 12 hours at 160 ℃; and naturally cooling to room temperature, taking all samples, centrifugally separating, washing with deionized water and ethanol twice respectively, and then placing in an oven at 60 ℃ for 12h for drying to be tested.

X-ray diffraction detection (XRD) of an appropriate sample is shown in FIGS. 2 and 9, and 3 at the upper right corner of FIG. 9 represents 200 nm. As shown in fig. 10 and 11, the results of field emission electron microscope (SEM) examination and Transmission Electron Microscope (TEM) examination are shown in fig. 10 and 11, and it is understood that the shape of the 200nm barium molybdate is polygonal-like.

The barium molybdate nanoparticles prepared in the above examples 2, 3 and 4 were subjected to X-ray diffraction detection, and the XRD patterns of the products are shown in fig. 2 and 5. XRD pattern confirms that the prepared product is BaMoO₄(the XRD pattern is consistent with that of JCPDS card number 29-0193 barium molybdate), and the crystallinity of the sample is better. BaMoO with different nanometer sizes can be obtained by changing the reaction time₄The method of the invention has better regulation and control performance. In addition, synthetic BaMoO₄Having different properties in terms of electroluminescence, etc., which is an extended BaMoO₄The application of the material provides the possibility.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method of preparing nano-sized barium molybdate particles, characterized in that: synthesizing nano barium molybdate by using a W/O microemulsion consisting of diethyl malonate, ethanol and water as a template and adopting a double microemulsion method;

constructing a diethyl malonate/ethanol/water microemulsion system;

mixing the aqueous solution of barium salt with diethyl malonate and ethanol to obtain W/O microemulsion of barium salt;

mixing the aqueous solution of molybdate with diethyl malonate and ethanol to obtain W/O microemulsion of molybdate;

dropwise adding the W/O microemulsion of barium salt into the W/O microemulsion of molybdate to react to obtain a product, and washing and drying the product to obtain nano barium molybdate;

the barium salt is BaCl₂Wherein the molybdate is Na₂MO₄An aqueous solution.

2. The method of claim 1, wherein: na (Na)₂MoO₄Microemulsion and BaCl₂The mass ratio of the ethanol to the diethyl malonate to the water in the microemulsion is equal.

3. The method of claim 2, wherein: in the W/O microemulsion of the barium salt, the mass ratio of the barium salt aqueous solution, the ethanol and the diethyl malonate is 3.0:7.0: 9.2.

4. The method of claim 3, wherein: in W/O microemulsion of molybdate, Na₂MO₄The mass ratio of the aqueous solution, ethanol and diethyl malonate is 3.0:7.0: 9.2.

5. The method of claim 1, wherein: the concentrations of the barium salt and the molybdate are the same and are 0.025 mol/L.

6. The method of claim 1, wherein: na (Na)₂MoO₄Microemulsion and BaCl₂The microemulsion reaction is carried out at room temperature or hydrothermal reaction to obtain the nano barium molybdate.

7. The method of claim 6, wherein: the reaction time at room temperature is 90-110h, 10-14h or 22-26 h.

8. The method of claim 1, wherein: na (Na)₂MoO₄Microemulsion and BaCl₂The microemulsion reaction condition is that hydrothermal reaction is carried out after mixing at room temperature.

9. The method of claim 8, wherein: the temperature of the hydrothermal reaction is 150-170 ℃, and the time of the hydrothermal reaction is 10-14 h.

10. The method of claim 2, wherein: the method for washing the barium molybdate nano material is to wash the barium molybdate nano material by using deionized water and ethanol in sequence.

11. The method of claim 2, wherein: the drying method is drying for 10-14h in an oven at 50-70 ℃.

12. The barium molybdate nanomaterial prepared by the method of any one of claims 1 to 11.

13. The barium molybdate nanomaterial of claim 12, wherein: the particle size of the barium molybdate nano material is 50-200 nm.

14. Use of the barium molybdate nanomaterial of claim 12 or 13 in the preparation of an electroluminescent material.