Apparatus and method for regulating morphology of metal oxalate precipitation

Abstract

The present application relates to a kind of device and method for regulating metal oxalate precipitation morphology, the device includes first-stage micro-mixer and second-stage micro-mixer in series with the first-stage micro-mixer, the outlet end of the first-stage micro-mixer is connected with the inlet end of the second-stage micro-mixer by pipeline, and the outlet end of the second-stage micro-mixer is also connected with collector by pipeline.The method is: the nitric acid solution in the first syringe, the europium nitrate solution in the second syringe and the oxalic acid solution in the third syringe are mixed to obtain precipitate and mother liquor, and the precipitate is dried after washing to obtain metal oxalate precipitate with different morphology, wherein the nitric acid solution and / or oxalic acid solution is added to the mixture at different flow rates.Compared with prior art, the present application can effectively regulate the morphology of metal oxalate precipitate in real time by changing the flow rate of raw materials, and the flow rate parameters of raw materials are easy to adjust, so that continuous batch operation can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oxalate preparation, and particularly to a device and method for regulating the precipitation morphology of metal oxalate. BACKGROUND

[0002] In recent years, with the development of material industry, metal oxides, especially rare earth oxides, are widely used as fluorescent materials, colored glass, catalytic materials, etc. The chemical and physical properties of functional materials composed of rare earth oxides are closely related to their size and shape, and the requirements for the morphology, size, chemical activity and other physical and chemical properties of rare earth compounds in the technical field are gradually increasing. Therefore, the precise design and synthesis of rare earth oxide materials with special morphology and adjustable size are attracting strong attention from researchers. At present, people have successfully prepared various inorganic compounds with hierarchical structure through synthesis methods such as self-propagating combustion, precipitation method, solvothermal method and sol-gel method, and have screened out some powdery materials with specific micro-nano structure. Among these methods, the precipitation method is a cost-effective, efficient and easy-to-produce method, and is also the most widely used method for preparing rare earth oxide precursors. In the existing precipitation reaction, the nucleation and growth process of the crystal is mainly affected by adjusting the raw material ratio and the mixing degree of the reactor, which is relatively complex to realize. SUMMARY

[0003] The present application aims to overcome the above-mentioned defects of the prior art, i.e. the need to simultaneously adjust the raw material ratio and the mixing degree of the reactor to affect the nucleation and growth process of the crystal, and provides a device and method for regulating the precipitation morphology of metal oxalate.

[0004] The object of the present application can be achieved by the following technical solutions:

[0005] One of the technical solutions of the present application is to provide a device for regulating the precipitation morphology of metal oxalate, comprising a first-stage micro-mixer and a second-stage micro-mixer connected in series with the first-stage micro-mixer, the outlet end of the first-stage micro-mixer being connected to the inlet end of the second-stage micro-mixer through a pipeline, and the outlet end of the second-stage micro-mixer being further connected to a collector through a pipeline.

[0006] Further, the first-stage micro-mixer and the second-stage micro-mixer are both passive mixers.

[0007] Still further, the first-stage micro-mixer is a T-shaped micro-mixer, and the second-stage micro-mixer is a Y-shaped micro-mixer.

[0008] Further, two inlet ends of the first-stage micro-mixer are respectively connected with a first injector and a second injector, and two inlet ends of the second-stage micro-mixer are respectively connected with an outlet end of the first-stage micro-mixer and a third injector.

[0009] The second technical scheme of the present application provides a method for regulating the morphology of metal oxalate precipitation, and the method comprises the following steps:

[0010] (1) nitric acid solution, europium nitrate solution and oxalic acid solution are respectively configured in the first injector, the second injector and the third injector;

[0011] (2) the nitric acid solution in the first injector (1) and the europium nitrate solution in the second injector (2) are flowed into the first-stage micro-mixer (4), and then the mixture is continuously flowed into the second-stage micro-mixer (5) and mixed with the oxalic acid solution injected through the third injector (3) to react, and then the obtained reaction product is filtered, washed and dried to obtain the metal oxalate precipitation;

[0012] In step (2), the morphology of the obtained metal oxalate precipitation is regulated by regulating the flow rates of the nitric acid solution and / or the oxalic acid solution.

[0013] Further, in step (1), the concentration of the nitric acid solution is 1M, the concentration of the europium nitrate solution is 0.4mM, and the concentration of the oxalic acid solution is 0.2M.

[0014] Further, in step (2), the flow rate of the nitric acid solution is 1-5mL / min.

[0015] Further, in step (2), the flow rate of the europium nitrate solution is 5mL / min.

[0016] Further, in step (2), the flow rate of the oxalic acid solution is 7-15mL / min.

[0017] Further, in step (2), the drying temperature is 80℃.

[0018] The nitric acid solution and the europium nitrate solution are mixed and flowed into the second-stage micro-mixer, the mixed solution flowed into the second-stage micro-mixer provides an acidic environment for the oxalic acid precipitation, and the precipitation reaction occurs immediately when the oxalic acid solution flowed into the second-stage micro-mixer contacts the mixed solution. The present application regulates the morphology of the obtained metal oxalate precipitation by regulating the flow rates of the nitric acid solution and the oxalic acid solution.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) Compared with the traditional kettle type precipitation mode, the morphology of the metal oxalate precipitation can be effectively controlled in real time by only changing the flow rate of the raw material.

[0021] (2) The process adopted by the present application is simple, the raw material flow rate parameter is easy to control, and continuous batch operation can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the device of the present application.

[0023] Figure 2 is an electron microscope morphology diagram of metal oxalate precipitation A in the example.

[0024] Figure 3 is an electron microscope morphology diagram of metal oxalate precipitation B in the example.

[0025] Figure 4 is an electron microscope morphology diagram of metal oxalate precipitation C in the example.

[0026] Figure 5 is an electron microscope morphology diagram of metal oxalate precipitation D in the example.

[0027] Figure 6 is an electron microscope morphology diagram of metal oxalate precipitation E in the example.

[0028] Figure 7 is a fluorescence emission spectrum diagram of the product after calcination of metal oxalate precipitation C in the example and a commercial europium oxide luminescent material.

[0029] The figures are identified as follows:

[0030] 1 - first syringe, 2 - second syringe, 3 - third syringe, 4 - first stage micro-mixer, 5 - second micro-mixer, 6 - collector. DETAILED DESCRIPTION

[0031] The present application will be described in detail below in conjunction with the drawings and specific examples.

[0032] In the following examples and comparative examples, if no special description is given for the raw materials or processing techniques, it means that they are all conventional commercially available raw material products or conventional processing techniques in the art.

[0033] Example 1:

[0034] Figure 1The device for regulating the morphology of metal oxalate precipitation of the application comprises a first-stage micro-mixer 4 and a second-stage micro-mixer 5 connected in series with the first-stage micro-mixer 4, the outlet end of the first-stage micro-mixer 4 is connected with the inlet end of the second-stage micro-mixer 5 through a pipeline, and the outlet end of the second-stage micro-mixer 5 is further connected with a collector 6 through a pipeline. The first-stage micro-mixer 4 and the second-stage micro-mixer 5 are both passive mixers, and preferably the first-stage micro-mixer 4 is a T-shaped micro-mixer and the second-stage micro-mixer 5 is a Y-shaped micro-mixer. The two inlet ends of the first-stage micro-mixer 4 are respectively connected with a first syringe 1 and a second syringe 2, and the two inlet ends of the second-stage micro-mixer 5 are respectively connected with the outlet end of the first-stage micro-mixer 4 and a third syringe 3.

[0035] The method for regulating the morphology of metal oxalate precipitation utilizes the above device to regulate the morphology of metal oxalate precipitation, comprising the following steps:

[0036] (1) 1M nitric acid solution, 0.4mM europium nitrate solution and 0.2M oxalic acid solution are respectively configured in the first syringe 1, the second syringe 2 and the third syringe 3;

[0037] (2) Firstly, the nitric acid solution and the europium nitrate solution in the first syringe 1 are passed into the first-stage micro-mixer 4 at a flow rate of 0.5mL / min, slowly flow into the second-stage micro-mixer 5, and then flow out from the outlet end of the second-stage micro-mixer 5. Then the europium nitrate solution in the second syringe 2 is passed into the first-stage micro-mixer 4 at a flow rate of 0.5mL / min and discharged, so as to make the nitric acid solution soak the first-stage micro-mixer 4 and the second-stage micro-mixer 5 and the europium nitrate solution soak the first-stage micro-mixer 4. After 2min, the europium nitrate solution in the second syringe 2 is flowed into the first-stage micro-mixer 4 from the inlet end of the first-stage micro-mixer 4 at a flow rate of 5mL / min, while the nitric acid solution in the first syringe 1 is flowed into the first-stage micro-mixer 4 from the inlet end of the first-stage micro-mixer 4 at different flow rates, and then discharged from the outlet end of the first-stage micro-mixer 4 to the second-stage micro-mixer 5 while mixing;

[0038] (3) Meanwhile, the oxalic acid solution in the third syringe 3 is flowed into the second-stage micro-mixer 5 from the inlet end of the second-stage micro-mixer 5 at a flow rate of 10mL / min to react, so as to obtain a reaction product which is discharged from the outlet end of the second-stage micro-mixer 5;

[0039] (4) The collector 6 filters and collects the precipitation, repeatedly rinses the precipitation with water, and then dries at 80℃ for 16h to obtain the metal oxalate precipitation.

[0040] The main reaction equation of the precipitation is as follows: Eu 3+ +H2C2O4→Eu2(C2O4)3↓+H +

[0041] The flow rates of the three solutions are as follows:

[0042]

[0043] Metal oxalate precipitate A, B and C were prepared by different flow rates of nitric acid solution. It was found by electron microscope that metal oxalate precipitate A was long strip shape (as shown in Figure 2 ), metal oxalate precipitate B was flower-shaped particles (as shown in Figure 3 ), and metal oxalate precipitate C was layered particles (as shown in Figure 4 ).

[0044] Metal oxalate precipitate C, D and E were prepared by different flow rates of oxalic acid solution. It was found by electron microscope that metal oxalate precipitate C was layered particles (as shown in Figure 4 ), metal oxalate precipitate D was block-shaped particles (as shown in Figure 5 ), and metal oxalate precipitate E was needle-shaped particles (as shown in Figure 6 ).

[0045] Metal oxalate precipitate A and D, and metal oxalate precipitate B and E were prepared by different flow rates of nitric acid solution and oxalic acid solution. It was found by electron microscope that metal oxalate precipitate A was long strip shape (as shown in Figure 2 ), metal oxalate precipitate D was block-shaped particles (as shown in Figure 5 ). Metal oxalate precipitate B was flower-shaped particles (as shown in Figure 3 ), and metal oxalate precipitate E was needle-shaped particles (as shown in Figure 6 ).

[0046] The fluorescence emission spectrum of calcined metal oxalate precipitate C was observed under 255 nm excitation light, and the results are shown in Figure 7 . The sample of calcined metal oxalate precipitate C (labeled as As-prepared in the figure) has higher fluorescence performance than the commercial europium oxide luminescent material (labeled as Commercial in the figure) of the same weight.

[0047] In summary, it can be seen that adjusting the flow rates of nitric acid solution and oxalic acid solution plays an important role in the morphology of metal oxalate precipitate. When the flow rate of oxalic acid solution is constant, increasing the flow rate of nitric acid solution leads to an increase in the acidity of the whole system, which makes the morphology of metal oxalate precipitate change from fine strip to layered particles, as shown in Figures 2-4 . When the flow rate of nitric acid solution is fixed, increasing the flow rate of oxalic acid solution leads to a change in the supersaturation of the whole system, which makes the morphology of metal oxalate precipitate change from layered particles to needle-shaped particles, as shown in Figures 5-6The morphology of the metal oxalate precipitate changes (such as shown in Figs. 1-6) when the flow rate of both the nitric acid solution and the oxalic acid solution is increased, depending on the acidity and supersaturation of the whole system. Figure 2 , 5 or 3, 6).

[0048] Comparative Example 1:

[0049] Compared with Example 1, most of them are the same, the difference is that the flow rate of europium nitrate solution is changed from 5 mL / min to 10 mL / min, which are marked as A'-E' respectively.

[0050] The metal oxalate precipitates A'-E' prepared in the experiment are observed by electron microscope, and it is found that they are similar to the metal oxalate precipitates A-E in Example 1 respectively. It is shown that changing the flow rate of europium nitrate solution is not a necessary feature to control the morphology of metal oxalate precipitate.

[0051] The above description of the examples is for the purpose of facilitating the understanding and use of the invention by those skilled in the art. Those skilled in the art can easily make various modifications to the examples, and apply the general principles described herein to other examples without creative labor. Therefore, the present invention is not limited to the above examples, and the improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for regulating the morphology of metal oxalate precipitation, characterized in that, The device for implementing the method for regulating the morphology of metal oxalate precipitation comprises a first-stage micro-mixer (4) and a second-stage micro-mixer (5) connected in series with the first-stage micro-mixer (4), the outlet end of the first-stage micro-mixer (4) is connected with the inlet end of the second-stage micro-mixer (5) through a pipeline, and the outlet end of the second-stage micro-mixer (5) is further connected with a collector (6) through a pipeline; The two inlet ends of the first-stage micro-mixer (4) are respectively connected with a first syringe (1) and a second syringe (2), and the two inlet ends of the second-stage micro-mixer (5) are respectively connected with the outlet end of the first-stage micro-mixer (4) and a third syringe (3); The method for regulating the morphology of metal oxalate precipitation comprises the following steps: (1) nitric acid solution, europium nitrate solution and oxalic acid solution are respectively configured in the first syringe (1), the second syringe (2) and the third syringe (3); (2) the nitric acid solution in the first syringe (1) and the europium nitrate solution in the second syringe (2) are flowed into the first-stage micro-mixer (4), mixed and then continuously flowed into the second-stage micro-mixer (5), and mixed and reacted with the oxalic acid solution injected through the third syringe (3), and after the obtained reaction product is filtered, washed and dried, the metal oxalate precipitation is obtained; In step (2), the morphology of the obtained metal oxalate precipitation is regulated by regulating the flow rate of the nitric acid solution and / or the oxalic acid solution, specifically: when the flow rate of the oxalic acid solution is unchanged, the flow rate of the nitric acid solution is increased, the acidity of the whole system is increased, and the morphology of the metal oxalate precipitation is gradually changed from a fine strip to a layered particle; when the flow rate of the nitric acid solution is fixed, the flow rate of the oxalic acid solution is increased, the supersaturation of the whole system is changed, and the morphology of the metal oxalate precipitation is changed from a layered particle to a needle-shaped particle.

2. The method of claim 1, wherein the metal oxalate is selected from the group consisting of calcium oxalate, magnesium oxalate, sodium oxalate, potassium oxalate, and combinations thereof. In step (1), the concentration of the nitric acid solution is 1 M, the concentration of the europium nitrate solution is 0.4 mM, and the concentration of the oxalic acid solution is 0.2 M.

3. The method of claim 1, wherein the metal oxalate is selected from the group consisting of calcium oxalate, magnesium oxalate, sodium oxalate, potassium oxalate, and combinations thereof. In step (2), the flow rate of the nitric acid solution is 1-5 mL / min.

4. The method of claim 1, wherein the metal oxalate is selected from the group consisting of calcium oxalate, magnesium oxalate, sodium oxalate, potassium oxalate, and combinations thereof. In step (2), the flow rate of the europium nitrate solution is 5 mL / min.

5. The method of claim 1, wherein the metal oxalate is selected from the group consisting of calcium oxalate, magnesium oxalate, sodium oxalate, potassium oxalate, and combinations thereof. In step (2), the flow rate of the oxalic acid solution is 7-15 mL / min.

6. The method of claim 1, wherein the metal oxalate is selected from the group consisting of calcium oxalate, magnesium oxalate, sodium oxalate, potassium oxalate, and combinations thereof. In step (2), the drying temperature is 80°C.

7. The method of claim 1, wherein the metal oxalate is selected from the group consisting of calcium oxalate, magnesium oxalate, sodium oxalate, potassium oxalate, and combinations thereof. The first-stage micro-mixer (4) and the second-stage micro-mixer (5) are both passive mixers.

8. The method of claim 1, wherein the metal oxalate is selected from the group consisting of calcium oxalate, magnesium oxalate, sodium oxalate, potassium oxalate, and combinations thereof. The first-stage micro-mixer (4) is a T-shaped micro-mixer, and the second-stage micro-mixer (5) is a Y-shaped micro-mixer.

Images