Method and device for continuously preparing nano lanthanum hydroxide under ultrasonic condition

Abstract

The invention discloses a method and a device for continuously preparing nano lanthanum hydroxide under an ultrasonic condition. The method for continuously preparing nano lanthanum hydroxide under the ultrasonic condition comprises the following steps: preparing an alkali solution and a lanthanum salt solution; the preparation method comprises the following steps: synchronously adding an alkali solution and a lanthanum salt solution into a tubular reactor, simultaneously carrying out continuous mixing reaction under an ultrasonic condition, and then carrying out centrifugal washing and drying to obtain the nano lanthanum hydroxide. According to the invention, the reaction of alkali and lanthanum salt is carried out in the tubular reactor, and ultrasonic wave is used for strengthening impact and material mixing, so that the reaction rate is accelerated, the raw materials are contacted more sufficiently, the dispersion degree is higher, particle aggregation is effectively inhibited, and the preparation of the lanthanum hydroxide nanocrystal with uniform size is facilitated. The synthesis process is simple, continuous preparation can be achieved, the reaction is completed at a time, the reaction period is short, a surfactant does not need to be used, the cleaning process is simple and safe, operation is easy, repeatability is good, and the prepared nano lanthanum hydroxide nanocrystals are small in size and more uniform.

Description

Technical Field

[0001] The invention relates to the technical field of nano material preparation, and in particular to a method and a device for continuously preparing nano lanthanum hydroxide under ultrasonic conditions. Background Art

[0002] Lanthanum is one of the rare elements in nature. Trivalent lanthanum ion compounds have a strong affinity with phosphorus and low oral bioavailability. They combine with phosphorus in food in the gastrointestinal tract to form lanthanum phosphate molecules with low water solubility and poor permeability through biological membranes, and are excreted from the body with feces, thereby achieving the purpose of reducing blood phosphorus and effectively controlling hyperphosphatemia. Therefore, they can be used in the field of phosphate binders. Nanostructured lanthanum hydroxide has a larger specific surface area and reactivity, so it can improve the phosphorus removal effect of phosphate binders.

[0003] At present, there are three methods for preparing lanthanum hydroxide: precipitation method, microemulsion method, hydrothermal method, etc. Among them, the precipitation method is the most widely used, but the process is complicated, the raw material consumption is large, the purity is low, the product particle size is large, and the distribution is uneven. The microemulsion method usually forms a reverse microemulsion medium to produce La (OH) 3. The La (OH) 3 prepared by this method has a small particle size, a controllable particle size, and can be carried out at room temperature and pressure. The reaction is mild, the equipment is simple, and it is easy to control. However, this method consumes a large amount of solvents, surfactants, and co-surfactants, and the cost is high. It is difficult to remove these organic substances from the surface of the product particles. The product has a high impurity content, and industrial-scale production is very difficult. The hydrothermal method requires reaction under high temperature and high pressure conditions in the reactor. The reaction conditions are relatively strict and the reaction time is long.

[0004] Therefore, there is an urgent need to provide a preparation process of lanthanum hydroxide to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies and to provide a method and device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions, so as to solve the technical problems in the prior art that the preparation of nano-lanthanum hydroxide is complicated, the reaction temperature is high and an auxiliary agent needs to be introduced.

[0006] In a first aspect, the present invention provides a method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions, comprising the following steps: preparing an alkali solution and a lanthanum salt solution; The alkaline solution and the lanthanum salt solution are added into the tubular reactor simultaneously, and a continuous mixing reaction is carried out under ultrasonic conditions, and then the nano-lanthanum hydroxide is obtained by centrifugal washing and drying.

[0007] In a second aspect, the present invention provides a nano-lanthanum hydroxide, which is obtained by the method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions provided by the first aspect of the present invention.

[0008] In a third aspect, the present invention provides a device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions, the device comprising: an alkaline solution raw material tank, a lanthanum salt solution raw material tank, a tubular reactor, a primary product receiver, and an ultrasonic generator; The feed port of the tubular reactor is connected to the alkali solution raw material tank and the lanthanum salt solution raw material tank, and the discharge port of the tubular reactor is connected to the primary product receiver; The ultrasonic generator comprises a water bath, and the tubular reactor is arranged in the water bath.

[0009] Compared with the prior art, the beneficial effects of the present invention include: The present invention conducts the reaction of alkali and lanthanum salt in a tubular reactor, strengthens the impact by ultrasonic wave, strengthens the mixing of materials, thereby accelerating the reaction rate, making the raw materials contact more fully, and the dispersion degree greater, effectively suppressing the agglomeration of particles, and facilitating the preparation of lanthanum hydroxide nanocrystals with uniform size. The present invention has a simple synthesis process, can be prepared continuously, the reaction is completed once, the reaction cycle is short, no surfactant is needed, the cleaning process is simple and safe, and the operation is simple, the repeatability is good, and the prepared nano-lanthanum hydroxide nanocrystals are smaller in size and more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic structural diagram of an embodiment of a device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions provided by the present invention; wherein 1 is an alkaline solution raw material tank, 2 is a lanthanum salt solution raw material tank, 3 is a tubular reactor, 4 is a primary product receiver, 5 is an ultrasonic generator, 6 is a peristaltic pump, 7 is a three-way connector, 8 is a first connecting pipe, and 9 is a second connecting pipe; Figure 2 XRD diagram of nano-lanthanum hydroxide prepared in Examples 1 to 6 of the present invention; Figure 3 TEM images of nano-lanthanum hydroxide prepared in Examples 1 to 6 of the present invention; wherein (a) is Example 1, (b) is Example 2, (c) is Example 3, (d) is Example 4, (e) is Example 5, and (f) is Example 6; Figure 4 TEM images of nano-lanthanum hydroxide prepared in Comparative Examples 1 to 3 of the present invention; wherein (a) and (b) are Comparative Example 1, (c) and (d) are Comparative Example 2, and (e) and (f) are Comparative Example 3. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0012] In a first aspect, the present invention provides a method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions, comprising the following steps: S1. preparing an alkali solution and a lanthanum salt solution; S2. Adding the alkaline solution and the lanthanum salt solution into the tubular reactor simultaneously, and performing continuous mixing reaction under ultrasonic conditions, followed by centrifugal washing and drying to obtain nano lanthanum hydroxide.

[0013] The present invention conducts the reaction of alkali and lanthanum salt in a tubular reactor. Under ultrasonic conditions, the liquid raw material will generate strong vibration and impact force when propagating, producing the effect of mixing and stirring. Through ultrasonic wave-enhanced impact, the two strengthening means of impact flow and ultrasonic wave are used to further strengthen the mixing of materials, thereby accelerating the reaction rate, promoting particle dispersion, and generating a high-speed micro-jet effect. Under these conditions, the raw materials are more fully contacted, the degree of dispersion is greater, and particle agglomeration is effectively suppressed, which is conducive to the preparation of lanthanum hydroxide nanocrystals with uniform size. In addition, the present invention can regulate the size of nano-lanthanum hydroxide by changing the concentration, flow rate, reaction temperature and ultrasonic power of nano-lanthanum hydroxide raw materials; the synthesis process of the present invention is simple, can be prepared continuously, the reaction is completed once, the reaction cycle is short, no surfactant is needed, the cleaning process is simple and safe, and the operation is simple, the repeatability is good, and the prepared nano-lanthanum hydroxide nanocrystals are smaller and more uniform in size.

[0014] In this embodiment, in the alkaline solution and the lanthanum salt solution, the molar ratio of hydroxide to lanthanum is greater than 3:1, preferably (3.05-3.5):1, and more preferably 3.1:1.

[0015] In this embodiment, in step S1, the base is at least one of sodium hydroxide, potassium hydroxide, and ammonia water.

[0016] In this embodiment, in step S1, the concentration of the alkaline solution is 0.062 ~ 3.1 mol·L -1 , further to 0.077~ 3.1 mol·L -1 .

[0017] In this embodiment, in step S1, the lanthanum salt is at least one of lanthanum chloride and lanthanum nitrate.

[0018] In this embodiment, in step S1, the concentration of the lanthanum salt is 0.02 to 1 mol·L -1 , further 0.025 ~ 1mol·L -1 .

[0019] In this embodiment, in step S1, during the simultaneous addition, the flow rates of the alkaline solution and the lanthanum salt solution are both 0.768-3.072 ml / min.

[0020] Preferably, the flow rates of the base solution and the lanthanum salt solution are the same.

[0021] In this embodiment, in step S1, the alkaline solution and the lanthanum salt solution are simultaneously added to the tubular reactor through a peristaltic pump, and the rotation speed of the peristaltic pump is 15 to 60 r / min.

[0022] In this embodiment, in step S2, the temperature of the continuous mixing reaction is 25-80° C., and the time of the continuous mixing reaction is 0.5-11 min.

[0023] In this embodiment, in step S2, the power of the ultrasound is 40 to 100 kW, further 70 to 100 kW.

[0024] In a second aspect, the present invention provides a nano-lanthanum hydroxide, which is obtained by the method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions provided by the first aspect of the present invention.

[0025] In a third aspect, the present invention provides a device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions, the device comprising: an alkaline solution raw material tank 1, a lanthanum salt solution raw material tank 2, a tubular reactor 3, a primary product receiver 4, and an ultrasonic generator 5; The feed port of the tubular reactor 3 is connected to the alkali solution raw material tank 1 and the lanthanum salt solution raw material tank 2, and the discharge port of the tubular reactor 3 is connected to the primary product receiver 4; The ultrasonic generator 5 comprises a water bath, and the tubular reactor 3 is arranged in the water bath.

[0026] In this embodiment, the tubular reactor 3 is a glass spiral tube with an inner diameter of 2 mm, an outer diameter of 4 mm, a spiral diameter of 50 mm, a spiral number of 5 to 35, and a total length of 86.5 to 557.5 cm.

[0027] In this embodiment, the ultrasonic generator 5 is a numerically controlled ultrasonic cleaner, and the specific model is KQ5200DE.

[0028] In this embodiment, the feed end of the tubular reactor 3 is also provided with a peristaltic pump 6, a three-way joint 7 and a first connecting pipe 8. The two feed ports of the three-way joint 7 are respectively connected to the alkaline solution raw material tank 1 and the lanthanum salt solution raw material tank 2 through the pipeline of the peristaltic pump 6, and the discharge port of the three-way joint 7 is connected to the feed port of the tubular reactor 3 through the first connecting pipe 8.

[0029] Preferably, the three-way connector 7 is a Y-shaped three-way connector.

[0030] In this embodiment, a second connecting pipe 9 is further provided at the discharge end of the tubular reactor 3 , and the discharge port of the tubular reactor 3 is connected to the primary product receiver 4 through the second connecting pipe 9 .

[0031] Preferably, the first connecting tube 8 and the second connecting tube 9 are both silicone hoses.

[0032] Preferably, the length of the first connecting tube 8 is 10 cm; the length of the second connecting tube 9 is 18 cm.

[0033] Example 1 Prepare 50 ml of 0.025 mol·L -1 100ml of lanthanum chloride solution, prepare 50ml of sodium hydroxide solution at a ratio of hydroxide ion: lanthanum ion = 3.1:1, and mix the two solutions according to Figure 1 The device reacts, the peristaltic pump rate is 15 r / min, the flow rate is 0.768ml / min, the ultrasonic power is 70 kW, the reaction temperature is 25 ℃, the inner diameter of the glass spiral pipe is 2mm, the outer diameter is 4mm, the spiral diameter is 50mm, the number of spiral turns is 35, the total length of the glass spiral pipe is 557.5cm, the length of the first connecting pipe 8 is 10cm, the length of the second connecting pipe 9 is 18cm, and the time for the liquid to go from the three-way joint to the primary product receiver is 620s. The primary product receiver is used for collection, centrifuged and washed three times with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The XRD spectrum of lanthanum hydroxide prepared under this condition is shown in Figure 2 As shown in the TEM image Figure 3 As shown in (a). Under the preparation conditions of Example 1, the average length of n-LH is 32.58±10.85 nm, and the product has a small particle size, uniform distribution and good dispersibility.

[0034] Example 2 Prepare 50 ml of 0.025 mol·L -1 100ml of lanthanum chloride solution, prepare 50ml of sodium hydroxide solution at a ratio of hydroxide ion: lanthanum ion = 3.1:1, and mix the two solutions according to Figure 1 The device reacts, controls the peristaltic pump rate to 60r / min, the flow rate to 3.072ml / min, the ultrasonic power to 100 kW, the reaction temperature to 25°C, the inner diameter of the glass spiral tube to be 2mm, the outer diameter to be 4mm, the spiral diameter to be 50mm, the number of spiral turns to be 35, the total length of the glass spiral tube to be 557.5cm, the length of the first connecting tube 8 to be 10cm, the length of the second connecting tube 9 to be 18cm, and the time for the liquid to travel from the three-way joint to the primary product receiver to be 155s. The primary product receiver is used for collection, centrifuged and washed three times with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The XRD spectrum of lanthanum hydroxide prepared under this condition is shown in FIG. Figure 2 As shown in the TEM image Figure 3 As shown in (b), under the preparation conditions of Example 2, the average length of n-LH is 47.45±14.16 nm, and the product has a small particle size, uniform distribution and good dispersibility.

[0035] Example 3 Prepare 50 ml of 0.025 mol·L -1 100ml of lanthanum chloride solution, prepare 50ml of sodium hydroxide solution at a ratio of hydroxide ion: lanthanum ion = 3.1:1, and mix the two solutions according to Figure 1 The device reacts, controls the peristaltic pump rate to be 15r / min, the flow rate to be 0.768ml / min, the ultrasonic power to be 100 kW, the reaction temperature to be 25°C, the inner diameter of the glass spiral tube to be 2mm, the outer diameter to be 4mm, the spiral diameter to be 50mm, the number of spiral turns to be 35, the total length of the glass spiral tube to be 557.5cm, the length of the first connecting tube 8 to be 10cm, the length of the second connecting tube 9 to be 18cm, and the time for the liquid to travel from the three-way joint to the primary product receiver to be 620s. The primary product receiver is used for collection, centrifuged and washed three times with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The XRD spectrum of lanthanum hydroxide prepared under this condition is shown in FIG. Figure 2 As shown in the TEM image Figure 3 As shown in (c), under the preparation conditions of Example 3, the average length of n-LH is 37.75±9.80 nm, and the product has a small particle size, uniform distribution and good dispersibility.

[0036] Example 4 Prepare 50 ml of 0.025 mol·L -1 100ml of lanthanum chloride solution, prepare 50ml of sodium hydroxide solution at a ratio of hydroxide ion: lanthanum ion = 3.1:1, and mix the two solutions according to Figure 1 The device reacts, controls the peristaltic pump rate to 60r / min, the flow rate to 3.072ml / min, the ultrasonic power to 100 kW, the reaction temperature to 25°C, the inner diameter of the glass spiral tube to be 2mm, the outer diameter to be 4mm, the spiral diameter to be 50mm, the number of spiral turns to be 5, the total length of the glass spiral tube to be 86.5cm, the length of the first connecting tube 8 to be 10cm, the length of the second connecting tube 9 to be 18cm, and the time for the liquid to travel from the three-way joint to the primary product receiver to be 33s. The primary product receiver is used for collection, centrifuged and washed three times with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The XRD spectrum of lanthanum hydroxide prepared under this condition is shown in FIG. Figure 2 As shown in the TEM image Figure 3 As shown in (d), under the preparation conditions of Example 4, the average length of n-LH is 41.82±8.04 nm, and the product has a small particle size, uniform distribution and good dispersibility.

[0037] Example 5 Prepare 50 ml of 0.025 mol·L -1100ml of lanthanum chloride solution, prepare 50ml of sodium hydroxide solution at a ratio of hydroxide ion: lanthanum ion = 3.1:1, and mix the two solutions according to Figure 1 The device reacts, controls the peristaltic pump rate to 60r / min, the flow rate to 3.072ml / min, the ultrasonic power to 100 kW, the reaction temperature to 80°C, the inner diameter of the glass spiral tube to be 2mm, the outer diameter to be 4mm, the spiral diameter to be 50mm, the number of spiral turns to be 35, the total length of the glass spiral tube to be 557.5cm, the length of the first connecting tube 8 to be 10cm, the length of the second connecting tube 9 to be 18cm, and the time for the liquid to travel from the three-way joint to the primary product receiver to be 155s. The primary product receiver is used for collection, centrifuged and washed three times with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The XRD spectrum of lanthanum hydroxide prepared under this condition is shown in FIG. Figure 2 As shown in the TEM image Figure 3 As shown in (e), under the preparation conditions of Example 5, the average length of n-LH is 40.32±11.03 nm, and the product has a small particle size, uniform distribution and good dispersibility.

[0038] Example 6 Prepare 50 ml of 1 mol·L -1 100ml of lanthanum chloride solution, prepare 50ml of sodium hydroxide solution at a ratio of hydroxide ion: lanthanum ion = 3.1:1, and mix the two solutions according to Figure 1 The device reacts, controls the peristaltic pump rate to 60r / min, the flow rate to 3.072ml / min, the ultrasonic power to 100 kW, the reaction temperature to 25°C, the inner diameter of the glass spiral tube to be 2mm, the outer diameter to be 4mm, the spiral diameter to be 50mm, the number of spiral turns to be 35, the total length of the glass spiral tube to be 557.5cm, the length of the first connecting tube 8 to be 10cm, the length of the second connecting tube 9 to be 18cm, and the time for the feed liquid to travel from the three-way joint to the primary product receiver to be 155s. The primary product receiver is used for collection, centrifuged and washed three times with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The XRD spectrum of lanthanum hydroxide prepared under this condition is shown in FIG. Figure 2 As shown in the TEM image Figure 3 As shown in (f), under the preparation conditions of Example 6, the average length of n-LH is 39.84±13.64 nm, and the product has a small particle size, uniform distribution and good dispersibility.

[0039] like Figure 2As shown, the characteristic diffraction peak positions of 15.68°, 27.55°, 28.20°, 39.74°, and 48.73° of the XRD spectrum of n-LH prepared in Example 1 of the present invention are consistent with the characteristic peaks of 15.665°, 27.308°, 27.972°, 39.477°, and 48.643° in PDF#36-1481, corresponding to (100), (110), (101), (201), and (211) crystal planes, respectively, proving that the method of the present invention successfully prepares nano-lanthanum hydroxide.

[0040] Comparative Example 1 Compared with Example 1, the only difference is that no tubular reactor is used and no ultrasound is performed, and the lanthanum chloride solution and the sodium hydroxide solution are directly added dropwise to the primary product receiver at the same time for stirring reaction, as follows: Prepare 50 ml of 0.025 mol·L -1 Lanthanum chloride solution, 50ml sodium hydroxide solution is prepared at a ratio of hydroxide: lanthanum ion = 3.1:1, and the lanthanum chloride solution and sodium hydroxide solution are simultaneously added to the primary product receiver for stirring reaction. The peristaltic pump rate is 15 r / min, the flow rate is 0.768ml / min, and the reaction temperature is 25 ℃. After the addition is completed, stirring is stopped; centrifugal washing is performed three times with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The TEM image of lanthanum hydroxide prepared under this condition is shown in FIG. Figure 4 As shown in (a) and (b), under the preparation conditions of Comparative Example 1, the average length of n-LH is 100.67±40.85 nm.

[0041] Depend on Figure 4 (a) and (b) show that the lanthanum hydroxide nanocrystals prepared by this method have irregular shapes, large particle sizes, uneven particle size distribution, irregular morphology, poor uniformity, and are easy to agglomerate.

[0042] Comparative Example 2 Compared with Example 1, the only difference is that no tubular reactor is used, and the lanthanum chloride solution and the sodium hydroxide solution are directly added dropwise to the primary product receiver at the same time for ultrasonic reaction, as follows: Prepare 50 ml of 0.025 mol·L -1 Lanthanum chloride solution, 50ml sodium hydroxide solution is prepared at a ratio of hydroxide: lanthanum ion = 3.1:1, and the lanthanum chloride solution and sodium hydroxide solution are simultaneously added to the primary product receiver for ultrasonic reaction. The peristaltic pump rate is 15 r / min, the flow rate is 0.768ml / min, the reaction temperature is 25 ℃, and the ultrasonic power is 70kW. After the addition is completed, the ultrasound is stopped; it is washed three times by centrifugation with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The TEM image of lanthanum hydroxide prepared under this condition is shown in Figure 2. Figure 4As shown in (c) and (d), under the preparation conditions of Comparative Example 2, the average length of n-LH is 113.425±37.63 nm.

[0043] This method does not use a tubular reactor under the reaction conditions of Example 1. Figure 4 (c) and (d) show that the prepared lanthanum hydroxide nanocrystals have uncertain or irregular shapes, large particle sizes, and are easy to agglomerate.

[0044] Comparative Example 3 Compared with Example 1, the only difference is that no ultrasound is performed, and the lanthanum chloride solution and the sodium hydroxide solution are directly reacted continuously, as follows: Prepare 50 ml of 0.025 mol·L -1 100ml of lanthanum chloride solution, prepare 50ml of sodium hydroxide solution at a ratio of hydroxide ion: lanthanum ion = 3.1:1, and mix the two solutions according to Figure 1 The device was reacted, the peristaltic pump rate was 15 r / min, the flow rate was 0.768 ml / min, the reaction temperature was 25 °C, the inner diameter of the glass spiral pipe was 2 mm, the outer diameter was 4 mm, the spiral diameter was 50 mm, the number of spiral turns was 35, the total length of the glass spiral pipe was 557.5 cm, the length of the first connecting pipe 8 was 10 cm, the length of the second connecting pipe 9 was 18 cm, and the time for the liquid to travel from the three-way joint to the primary product receiver was 620 s. The primary product receiver was used for collection, centrifuged and washed three times with deionized water, and then freeze-dried to obtain lanthanum hydroxide nanocrystals. The TEM image of lanthanum hydroxide prepared under this condition is shown in Figure 2. Figure 4 As shown in (e) and (f), under the preparation conditions of Comparative Example 3, the average length of n-LH is 80.313±21.95 nm.

[0045] This method does not use ultrasonic means under the reaction conditions of Example 1. Figure 4 (e) and (f) show that the prepared lanthanum hydroxide nanocrystals have a rod-like structure, relatively uniform particle size distribution, and regular morphology, but the particle size is large and easy to agglomerate.

[0046] By comparing Examples 1-6 with Comparative Examples 1-3, it can be seen that the particle size of lanthanum hydroxide prepared in Examples 1-6 is smaller and the distribution is more uniform, indicating that the present application can not only improve the dispersibility of lanthanum hydroxide and avoid agglomeration through ultrasound + continuous reaction, but also obtain small-particle nano lanthanum hydroxide with uniform particle size distribution.

[0047] Compared with the prior art, the beneficial effects of the present invention include: (1) The present invention uses ultrasound + tubular reactor as the reaction site. Under the action of ultrasound, tensile stress appears inside the liquid, forming negative pressure. The pressure reduction causes the gas dissolved in the liquid to be supersaturated, escaping to form small bubbles. The tiny bubbles vibrate, grow and continuously accumulate energy under the action of the ultrasonic field. When the cavitation bubbles vibrate (steady-state cavitation) or collapse (transient cavitation), huge energy is released and microjets with fast speed and strong impact force are generated, so that the tiny particles in the liquid raw materials are impacted and rubbed, thereby enhancing mixing and mass transfer. The solution achieves efficient mixing during the flow process, which can resist the gravity deposition of solid powder, and can strengthen the reaction precipitation process, promote uniform nucleation, and prepare nanomaterials with uniform particles.

[0048] (2) The present invention combines the dual advantages of tubular reactors and ultrasound, and effectively solves the problem of low mixing efficiency in tubular reactions. The cavitation effect and micro-jet effect of ultrasound can enhance the mixing effect in the tubular reactor, making the reaction more uniform and efficient. The tubular reactor can also be designed with parameters such as flow form, flow rate, number of channels, etc. according to the requirements of different reactions.

[0049] (3) The device of the present invention is simple and can realize the rapid and continuous production of lanthanum hydroxide nanocrystals, avoiding the conventional discontinuous production and reducing its reaction cycle. It can obtain high-quality lanthanum hydroxide nanocrystals with a narrow particle size distribution in a relatively short time, and has good economic benefits and application prospects.

[0050] (4) The present invention has many advantages such as simple process, easy adjustment of structural parameters, strong operational controllability, stable product performance, and low energy consumption. It has strong industrialization conditions and prospects and can be scaled up to achieve the continuous preparation of nano-lanthanum hydroxide under industrial ultrasonic conditions.

[0051] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions, characterized in that: The following steps are involved: preparing an alkali solution and a lanthanum salt solution; The alkaline solution and the lanthanum salt solution are added into a tubular reactor simultaneously, and continuous mixing reaction is carried out under ultrasonic conditions, followed by centrifugal washing and drying to obtain nano lanthanum hydroxide.

2. The method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions according to claim 1, characterized in that: In the alkaline solution and the lanthanum salt solution, the molar ratio of hydroxide to lanthanum is greater than 3:

1.

3. The method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions according to claim 1, characterized in that: The alkali is at least one of sodium hydroxide, potassium hydroxide and ammonia water; and / or, The concentration of the alkaline solution is 0.062 ~ 3.1 mol·L -1 and / or, The lanthanum salt is at least one of lanthanum chloride and lanthanum nitrate; and / or, The concentration of the lanthanum salt is 0.02 ~ 1 mol·L -1 .

4. The method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions according to claim 1, characterized in that: During the simultaneous addition, the flow rates of the alkaline solution and the lanthanum salt solution are both 0.768-3.072 ml / min.

5. The method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions according to claim 1, characterized in that: The temperature of the continuous mixing reaction is 25-80° C., the time of the continuous mixing reaction is 0.5-11 min, and the power of the ultrasound is 40-100 kW.

6. A nano lanthanum hydroxide, characterized in that: The nano lanthanum hydroxide is obtained by the method for continuously preparing nano lanthanum hydroxide under ultrasonic conditions as described in any one of claims 1 to 5.

7. A device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions, characterized in that: The device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions comprises: an alkaline solution raw material tank, a lanthanum salt solution raw material tank, a tubular reactor, a primary product receiver and an ultrasonic generator; wherein: The feed port of the tubular reactor is connected to the alkaline solution raw material tank and the lanthanum salt solution raw material tank, and the discharge port of the tubular reactor is connected to the primary product receiver; The ultrasonic generator comprises a water bath, and the tubular reactor is arranged in the water bath; The device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions is used to perform the method for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions as described in any one of claims 1 to 5.

8. The device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions according to claim 7, characterized in that: The tubular reactor is a glass spiral tube; and / or, The ultrasonic generator is a numerically controlled ultrasonic cleaner.

9. The device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions according to claim 7, characterized in that: The feeding end of the tubular reactor is also provided with a peristaltic pump, a three-way joint and a first connecting pipe, and the discharging end of the tubular reactor is also provided with a second connecting pipe; The two feed ports of the three-way joint are respectively connected to the alkaline solution raw material tank and the lanthanum salt solution raw material tank through the pipeline of the peristaltic pump, and the discharge port of the three-way joint is connected to the feed port of the tubular reactor through the first connecting pipe; The discharge port of the tubular reactor is connected to the primary product receiver through the second connecting pipe.

10. The device for continuously preparing nano-lanthanum hydroxide under ultrasonic conditions according to claim 9, characterized in that: The three-way connector is a Y-shaped three-way connector; The first connecting tube and the second connecting tube are both silicone hoses.

Images