CN113184971B

CN113184971B - Catalytic device, preparation method thereof and piezoelectric ultrasonic degradation equipment adopting catalytic device

Info

Publication number: CN113184971B
Application number: CN202110386577.0A
Authority: CN
Inventors: 王增梅; 梁秀晨
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2021-04-12
Filing date: 2021-04-12
Publication date: 2022-03-08
Anticipated expiration: 2041-04-12
Also published as: CN113184971A

Abstract

The invention discloses a catalytic device, a preparation method and piezoelectric ultrasonic degradation equipment adopting the catalytic device, wherein the catalytic device consists of a piezoelectric vibrator produced by a 3D printing technology, an upper surface electrode and a lower surface electrode, the piezoelectric ultrasonic degradation equipment comprises a shell, the shell is provided with a plurality of key position hole grooves for installing the catalytic device, a supporting base is arranged below the shell, a driving plate and a power supply are arranged in the supporting base, a folding handle is arranged above the shell, and a switch is arranged on the handle and used for controlling the piezoelectric ultrasonic degradation process. The device disclosed by the invention combines two technical means of piezoelectric catalysis and piezoelectric atomization during working, organic pollutants can be degraded by using a piezoelectric catalysis and ultrasonic atomization dual catalysis means in the same device, the improvement of the whole degradation effect is promoted, the recycling and recovery of the device can be quickly realized after piezoelectric ultrasonic degradation by folding the grip, the cost is saved, and the practical application is facilitated.

Description

Catalytic device, preparation method thereof and piezoelectric ultrasonic degradation equipment adopting catalytic device

Technical Field

The invention belongs to piezoelectric ultrasonic catalysis equipment, and particularly relates to a piezoelectric atomization catalysis device, a preparation method thereof and equipment for degrading organic pollutants by adopting the catalysis device.

Background

Along with the development of globalization, the environmental pollution phenomenon is increasingly serious due to the discharge of industrial wastewater, piezoelectric catalysis is a novel catalytic means, and the piezoelectric potential generated by a piezoelectric material under the action of an external force can effectively promote the separation and transfer of electron hole pairs, participate in the oxidation-reduction reaction in a solution to generate active oxygen groups, and degrade pollutants existing in the environment.

The piezoelectric material is usually a nano material, and the problems that the process cost is increased because the grain diameter of the piezoelectric nano material is small and a special means is needed for recycling are also existed in the production and use processes, and on the other hand, the piezoelectric material which is not recycled has secondary pollution in the solution; furthermore, piezo catalysis alone has limited ability to degrade contaminants. Therefore, how to prepare a piezoelectric material with a precise microstructure to improve the performance and how to further improve the degradation efficiency in the piezoelectric catalysis becomes an urgent problem to be solved.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a catalytic device which can simultaneously utilize a piezoelectric catalysis and ultrasonic atomization dual catalysis means; the second purpose of the invention is to provide a preparation method of the catalytic device for improving the piezoelectric coefficient by using the 3D printing technology; the third purpose of the invention is to provide a piezoelectric ultrasonic device for degrading organic waste gas or organic waste liquid by using the catalytic device.

The technical scheme is as follows: the catalytic device comprises a piezoelectric vibrator, wherein an upper electrode and a lower electrode which are used for applying bias voltage to the piezoelectric vibrator are respectively arranged on two sides of the piezoelectric vibrator, the upper electrode and the lower electrode are fixedly connected with conducting wires, and the conducting wires are connected with a driving circuit with the frequency consistent with that of the piezoelectric vibrator; the upper electrode is provided with a micropore for generating atomization, and the micropore vibrates together with the piezoelectric vibrator; and the outer surfaces of the upper electrode and the lower electrode are wrapped with waterproof gaskets for isolating liquid.

In the catalytic device, an external driving circuit converts an electric signal into a signal matched with the resonance frequency of the piezoelectric vibrator, so that the piezoelectric vibrator is controlled to vibrate under the driving of a certain frequency, the upper surface and the lower surface of the piezoelectric vibrator generate electric potential caused by deformation, and the electric potential drives an oxidation-reduction reaction to generate active free radicals to degrade pollutants; meanwhile, the micropores are formed in the upper electrode, and the degradation principle is that pollutant molecules are attacked by strong impact micro-jet to be degraded. In the actual operation process, under the vibration of the piezoelectric vibrator, the vicinity of the micropores is subjected to rapid vibration to generate high-strength water pressure, so that cavitation bubbles can be broken to generate microjet with the speed of 110m/s, pollutants are attacked to be degraded, and the integral catalytic device simultaneously comprises two catalytic means.

Furthermore, the diameter of the micropores is 16-20 mm.

Furthermore, the upper electrode covers the whole upper surface of the piezoelectric vibrator, so that the upper electrode and the micropores can better transmit the resonant motion of the piezoelectric vibrator.

The invention also provides a preparation method of the catalytic device, which comprises the following steps:

mixing piezoelectric material powder and polyvinyl alcohol to form piezoelectric slurry, then spraying the slurry through a 3D printer to form a thin layer, stacking the thin layer by layer to form a blank body, and sintering the printed blank body at high temperature to obtain a piezoelectric vibrator;

step two, adhesive metal layers on two sides of the piezoelectric vibrator are used as an upper electrode and a lower electrode, and a micropore is formed in the center of the upper electrode;

and step three, welding leads at the end parts of the upper electrode and the lower electrode, and wrapping waterproof gaskets outside the upper electrode and the lower electrode to prepare the catalytic device.

In the preparation method, the 3D printing technology is adopted to construct the objects layer by the three-dimensional rapid forming modes of fusing, bonding, photocuring and the like on the powdered metal and the ceramic, so that the piezoelectric vibrator with a complex shape is prepared, and the piezoelectric coefficient of the piezoelectric vibrator is greatly improved due to the fact that the microstructure of the piezoelectric vibrator is more accurate. Meanwhile, the 3D printing technology can also rapidly realize the cyclic utilization and the recovery of the device after piezoelectric ultrasonic degradation while ensuring the performance of the piezoelectric vibrator.

Further, in the first step, the mass ratio of the piezoelectric material powder to the polyvinyl alcohol is 20-40: 1; the piezoelectric material powder includes any one of titanate, niobate and zirconate, but is not limited to these, and the piezoelectric material powder is selected according to the piezoelectricity of the piezoelectric material itself, and a piezoelectric vibrator with a high piezoelectric coefficient is preferably selected.

Further, in the first step, the high precision of the control layer is in the range of 0.1-1 mm during 3D printing, and the printing speed is 5-20 mm/s; the sintering temperature is 1000-1450 ℃, and the sintering time is 3-5 h. The process parameters of high-temperature sintering further influence the application of the formed blank, and the reason of high-temperature sintering is that the piezoelectric material powder is easier to react at high temperature, so that the density of the piezoelectric material is improved, a piezoelectric phase with high crystallinity is favorably formed, and the piezoelectric performance is improved.

The invention further provides equipment for piezoelectric ultrasonic degradation of organic pollutants, which comprises the catalytic device and a shell, wherein a supporting base is arranged at the bottom of the shell, a plurality of key position hole grooves for mounting the catalytic device are formed in the shell, a power supply for driving signals and a driving plate for transmitting current signals to a piezoelectric vibrator are arranged in the supporting base, the positive electrode of the power supply is electrically connected with the driving plate, the driving plate is electrically connected with the upper electrode of the catalytic device through a lead, and the lower electrode of the catalytic device is connected with the negative electrode of the power supply through a lead.

Further, in order to achieve the purpose of catalysis, it is necessary to ensure that the alternating current frequency emitted by the driving plate is consistent with the driving frequency of the piezoelectric vibrator; and in order to further facilitate the control of the whole equipment, the shell is provided with a handle, a switch for controlling the operation or the closing of the catalytic device is arranged above the handle, and the switch is electrically connected with the power supply.

The working principle of the piezoelectric ultrasonic organic pollutant degradation equipment is as follows: the method comprises the following steps of putting a recyclable keyboard type composite piezoelectric atomization catalytic device into a container containing pollutant solution, opening a switch of the device, degrading pollutants along with time, wherein the degradation is caused by two reasons, firstly, a piezoelectric vibrator can vibrate under the drive of a certain frequency, the upper surface and the lower surface can generate electric potential caused by deformation, and the electric potential drives an oxidation-reduction reaction to generate active free radicals to degrade the pollutants; on the other hand, the local energy generated by piezo atomization in the vicinity of the micro-pores can create micro-jets in the water, thereby attacking the contaminants and degrading them. After the catalysis is finished, the device can be taken out for next degradation, so that the effect of recycling is achieved.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: (1) the device disclosed by the invention combines two technical means of piezoelectric catalysis and piezoelectric atomization during working, and can degrade organic pollutants by using a piezoelectric catalysis and ultrasonic atomization dual catalysis means in the same device, so that the whole degradation effect is promoted to be improved; (2) the piezoelectric vibrator is prepared by the 3D printing technology, the piezoelectric coefficient of the piezoelectric vibrator is improved, the device can be quickly recycled and recovered after piezoelectric ultrasonic degradation by folding the handle, the cost is saved, and the practical application is facilitated.

Drawings

FIG. 1 is a schematic view of the catalytic device of the present invention;

FIG. 2 is a schematic structural diagram of the piezoelectric ultrasonic organic pollutant degradation device of the present invention;

FIG. 3 is a graph of the degradation efficiency of catalytic rhodamine b with different micropore diameters;

FIG. 4 is a graph of the degradation efficiency of catalytic rhodamine b at different times.

Detailed Description

The technical solution of the present invention is further described in detail with reference to the accompanying drawings and examples.

The catalytic device shown in fig. 1 comprises a piezoelectric vibrator 6, an upper electrode 7 and a lower electrode 8 which are connected with the upper surface and the lower surface of the vibrator, a waterproof gasket 9 which wraps the electrodes, and a lead wire 10 which is welded with a motor, wherein micropores 14 are arranged on the upper electrode 7, and a central hole is arranged in the center of the lower electrode. The piezoelectric vibrator 6 can be prepared into a structure with a special shape by a 3D printing technology, vibration is generated under response of driving alternating current frequency, the upper electrode 7 and the lower electrode 8 are connected with the piezoelectric vibrator 6 through strong glue, bias voltage can be applied to the piezoelectric vibrator 6 by the upper electrode 7 and the lower electrode 8, the waterproof gasket 9 is used for isolating liquid and avoiding short circuit of a catalytic device, micropores 14 are formed in the upper electrode and used for generating atomization, and when the piezoelectric vibrator 6 works, the micropores 14 generate high-strength water pressure under the action of rapid high-frequency vibration to break nearby cavitation bubbles and attack pollutant molecules to decompose the pollutant molecules.

Referring to fig. 2, the piezoelectric ultrasonic organic pollutant degradation equipment comprises a shell 1, wherein a support base 2 is arranged below the shell 1, the support base 2 can enhance the structural strength of the catalytic device, a folding handle 3 is arranged above the shell 1, the folding handle 3 can improve the portability of the catalytic device, and the equipment can be directly taken out of a solution after the catalytic reaction is finished. The shell 1 is internally provided with a plurality of key hole grooves 4, an independent catalytic device 5 is correspondingly arranged in each key hole groove 4, a driving plate 11 is arranged on a supporting base and used for emitting alternating-current frequency corresponding to the driving frequency of the piezoelectric atomization sheet, a power supply 12 is arranged on one side of the driving plate 11 and used for supplying power and driving signals, the positive electrode of the power supply 12 is electrically connected with one end of the driving plate 11, the other end of the driving plate 11 is connected with an upper electrode 7 through a lead 10, and one end of a lower electrode 8 is connected with the negative electrode of the power supply 12 through a lead. A switch 13 is arranged above the folding handle and can control the operation of the catalytic device to be carried out and closed.

Example 1

The organic waste liquid is treated by the equipment, and the specific treatment steps are as follows:

mixing 4g of barium calcium zirconate titanate powder and 0.2g of polyvinyl alcohol to form piezoelectric slurry, spraying the slurry through a 3D printer to form a thin layer, stacking the thin layer by layer to form a blank, controlling the layer high precision within the range of 0.5mm during 3D printing, and sintering the printed blank at 1450 ℃ for 3 hours to obtain a piezoelectric vibrator, wherein the printing speed is 10 mm/s;

step two, gluing stainless steel metal layers on two sides of the piezoelectric vibrator to serve as an upper electrode and a lower electrode, and forming a micropore with the diameter of 16mm in the center of the upper electrode;

welding wires at the end parts of the upper electrode and the lower electrode and connecting the wires with an external driving circuit, and wrapping waterproof gaskets outside the upper electrode and the lower electrode to prepare the catalytic device;

and step four, mounting the prepared catalytic devices in the key position hole grooves 4, sequentially connecting a power supply 12 and a drive plate 11 to obtain piezoelectric ultrasonic equipment, then placing the equipment in a pollutant solution, wherein the pollutant is 1mg/L rhodamine b, pressing a switch 13, filling liquid in each catalytic device, driving current signals to flow to the upper and lower electrodes of the piezoelectric vibrator from the drive plate under the drive of an external power supply, and driving the piezoelectric vibrator to work, wherein the working time of piezoelectric catalysis is 2 hours. After the degradation is finished, the solution can be directly taken out of the solution and can be used for the next degradation treatment.

Example 2

mixing 8g of barium calcium zirconate titanate powder and 0.2g of polyvinyl alcohol to form piezoelectric slurry, spraying the slurry through a 3D printer to form a thin layer, stacking the thin layer by layer to form a blank, controlling the layer high precision to be within 0.1mm during 3D printing, and sintering the printed blank at 1000 ℃ for 5 hours to obtain a piezoelectric vibrator, wherein the printing speed is 5 mm/s;

step two, gluing stainless steel metal layers on two sides of the piezoelectric vibrator to serve as an upper electrode and a lower electrode, and forming a micropore with the diameter of 20mm in the center of the upper electrode;

and step four, mounting the prepared catalytic devices in the key position hole grooves 4, sequentially connecting a power supply 12 and a drive plate 11 to obtain piezoelectric ultrasonic equipment, then placing the equipment in a pollutant solution, wherein the pollutant is 1mg/L rhodamine b, pressing a switch 13, filling liquid in each catalytic device, driving the piezoelectric vibrators to work by driving current signals to flow to the upper and lower electrodes of the piezoelectric vibrators from the drive plate under the driving of an external power supply, and driving the piezoelectric vibrators to work, wherein the working time of piezoelectric catalysis is 4 hours. After the degradation is finished, the solution can be directly taken out of the solution and can be used for the next degradation treatment.

Example 3

step one, mixing 6g of lead titanate powder and 0.2g of polyvinyl alcohol to form piezoelectric slurry, then spraying the slurry through a 3D printer to form a thin layer, stacking the thin layer by layer to form a blank, controlling the layer high precision within a range of 1mm during 3D printing, and sintering the printed blank at 1300 ℃ for 5 hours at a printing speed of 20mm/s to obtain a piezoelectric vibrator;

step two, gluing stainless steel metal layers on two sides of the piezoelectric vibrator to serve as an upper electrode and a lower electrode, and forming a micropore with the diameter of 18mm in the center of the upper electrode;

Example 4

2 groups of parallel tests are designed, the specific treatment process is the same as that of the example 1, the same degradation time is 2 hours, and the difference is that the diameters of the micropores are different, specifically 16mm and 20mm respectively; the piezoelectric catalytic degradation rates of the final tests are shown in table 1 below and fig. 3.

TABLE 1

As can be seen from table 1 and fig. 3, at the same operation time 2h, when the diameter of the micro-hole is in the range of 20mm, the degradation rate is 19%, and when the diameter of the micro-hole is 16mm, the diameter of the micro-hole is lower, and the degradation rate is reduced due to the smaller contact area between the piezoelectric micro-jet generated at the micro-hole and the contaminant. Therefore, the diameter of the micropores needs to be limited, and the diameter of the micropores is too small, resulting in a low degradation rate as a whole.

Example 5

Designing 2 groups of parallel tests, wherein the specific treatment process is the same as that of example 1, and the same 20mm micropore diameter is formed, wherein the difference is in the catalysis time, specifically 2h and 4 h; the degradation rates of the final tests are shown in table 2 below and fig. 4.

TABLE 2

As can be seen from table 2 and fig. 4, at the same micropores of 20mm, as the catalysis time is prolonged, more active radicals are generated in the catalysis process, and the longer the catalysis time is, the piezoelectric microjet impacts on pollutant molecules for a longer time, so the catalytic degradation efficiency is also improved.

Claims

1. A catalytic device, characterized by: the piezoelectric vibrator comprises a piezoelectric vibrator (6), wherein an upper electrode (7) and a lower electrode (8) which are used for applying bias voltage to the piezoelectric vibrator are respectively arranged on two sides of the piezoelectric vibrator (6), a lead (10) is fixedly connected to the upper electrode (7) and the lower electrode (8), and the lead (10) is connected with a driving circuit (15) with the frequency consistent with that of the piezoelectric vibrator (6); the upper electrode (7) is provided with micropores (14) for generating atomization, and the micropores (14) vibrate together with the piezoelectric vibrator (6); the outer surfaces of the upper electrode (7) and the lower electrode (8) are wrapped with waterproof gaskets (9) for isolating liquid;

a method of making a catalytic device comprising the steps of:

mixing piezoelectric material powder and polyvinyl alcohol to form piezoelectric slurry, then spraying the slurry through a 3D printer to form a thin layer, stacking and forming layer by layer, and sintering a printed blank at high temperature to obtain a piezoelectric vibrator;

secondly, gluing metal layers on two sides of the piezoelectric vibrator (6) to serve as an upper electrode (7) and a lower electrode (8), and forming a micropore (14) in the center of the upper electrode (7);

welding a lead (10) at the end parts of the upper electrode (7) and the lower electrode (8), and wrapping waterproof gaskets (9) outside the upper electrode (7) and the lower electrode (8) to prepare the catalytic device;

in the first step, the mass ratio of the piezoelectric material powder to the polyvinyl alcohol is 20-40: 1; the piezoelectric material powder comprises any one of titanate, niobate and zirconate.

2. The catalytic device of claim 1, wherein: the diameter of the micropores (14) is 16-20 mm.

3. The catalytic device of claim 1, wherein: the upper electrode (7) covers the entire upper surface of the piezoelectric vibrator (6).

4. A method of manufacturing the catalytic device of claim 1, comprising the steps of:

and thirdly, welding a lead (10) at the end parts of the upper electrode (7) and the lower electrode (8), and wrapping waterproof gaskets (9) outside the upper electrode (7) and the lower electrode (8) to prepare the catalytic device.

5. The method of manufacturing a catalytic device according to claim 4, characterized in that: in the first step, the mass ratio of the piezoelectric material powder to the polyvinyl alcohol is 20-40: 1; the piezoelectric material powder comprises any one of titanate, niobate and zirconate.

6. The method of manufacturing a catalytic device according to claim 4, characterized in that: in the first step, the high precision of a control layer is in the range of 0.1-1 mm during 3D printing, and the printing speed is 5-20 mm/s; the sintering temperature is 1000-1450 ℃, and the sintering time is 3-5 h.

7. A piezoelectric ultrasonic degradation device is characterized in that: comprising a catalytic device (5) according to any of claims 1 to 3.

8. The piezoelectric ultrasonic degradation apparatus of claim 7, wherein: still include casing (1), the bottom of casing (1) is equipped with support base (2), be provided with a plurality of key position hole grooves (4) that are used for installing catalytic unit (5) in casing (1), be equipped with in support base (2) and be used for drive signal's power (12) and be used for transmitting current signal drive plate (11) for piezoelectric vibrator (6), the positive pole and drive plate (11) electric connection of power (12), drive plate (11) are through wire (10) and catalytic unit's last electrode (7) electric connection, and catalytic unit's bottom electrode (8) are connected through wire (10) and the negative pole of power (12).

9. The piezoelectric ultrasonic degradation apparatus of claim 8, wherein: the alternating current frequency emitted by the driving plate (11) is consistent with the driving frequency of the piezoelectric vibrator (6).

10. The piezoelectric ultrasonic degradation apparatus of claim 8, wherein: the catalytic device is characterized in that a handle (3) is arranged on the shell (1), a switch (13) for controlling the catalytic device (5) to work or be closed is arranged above the handle (3), and the switch (13) is electrically connected with the power supply (12).