CN102415836A - Method for cleaning fruit/vegetable by adopting ultrasonic-photocatalytic coupling - Google Patents

Abstract

The invention discloses an ultrasonic-photocatalytic coupling fruit and vegetable cleaning method. The method comprises the following steps: adding water to the cleaning box (1) or inner container (2) of the fruit and vegetable cleaning device, and placing the fruit and vegetable to be cleaned on a porous tray plate (4), adjust the height of the porous supporting plate (4) so that the fruits and vegetables to be cleaned are completely submerged in water; oxygen and/or air are introduced into the inner container (2) through the porous supporting plate (4) ) and generate a large number of bubbles, so that oxygen and/or air are fully dissolved in the water; turn on the ultrasonic generator; turn on the ultraviolet light source (3) through the control of the controller, and the ultraviolet light emitted by the ultraviolet light source (3) passes through the light-transmitting The window (5) emits onto the photocatalyst film of the inner tank (2), and the synergistic effect of ultrasonic waves, photocatalysis and oxygen causes a large number of hydroxyl radicals OH and negative oxygen ion radicals O ₂ ^- to be generated in the water. Oxidize and degrade the pesticide residues on the surface of fruits and vegetables. By adopting the method for cleaning fruits and vegetables, the degradation rate of pesticide residues on the surface of fruits and vegetables can reach 40%-70%.

Description

Ultrasonic-photocatalytic coupling fruit and vegetable cleaning method

technical field

The invention relates to the technical field of degradation of pesticide residues, in particular to an ultrasonic-photocatalytic coupled fruit and vegetable cleaning method.

Background technique

At present, my country has become the second largest pesticide user in the world. For vegetables and fruits with a short growth period, the use of pesticides has become very common due to the large number of pests. Excessive use of pesticides has led to increasing levels of pesticide residues. In the "2011 List of Pesticide Residues in Fruits and Vegetables" released by the US Environmental Working Group (EWG), apples top the list of fruits and vegetables with the most pesticide residues, which fully indicates that excessive pesticide residues in fruits and vegetables have become a global problem. Pesticide residues not only cause harm to people's health, but also a bottleneck restricting the export of agricultural products such as fruits and vegetables in our country.

In order to solve the problem of pesticide residues in fruits and vegetables, people need to clean the fruits and vegetables before eating. The fruit and vegetable cleaning machine in the prior art mainly achieves the purpose of sterilization by generating ozone molecules under high pressure. Excessive ozone is harmful to human health, and nitrogen oxides are easily generated when this fruit and vegetable cleaning machine is working. Nitrogen oxides have a stable molecular structure and are not easy to decompose. They are carcinogens and seriously threaten human health. For example, the patent CN201001659 introduces the ozone generated by the ozone generator into the water of the fruit and vegetable purification tank to form ozone water with oxidation effect, thereby decomposing the pesticide residues in the fruits and vegetables, killing harmful microorganisms, and effectively purifying the fruits and vegetables; the patent CN201163986 uses the combination of ozone oxidation and photocatalysis The method realizes the purpose of oxidative degradation of organic pollutants.

Most of the fruit and vegetable cleaning devices in the prior art use the method of ozone oxidation, which cannot eliminate the damage and threat to human health caused by excessive ozone, and the degradation efficiency of pesticide residues is low, and it is impossible to realize automatic and continuous cleaning of large quantities of fruits and vegetables. Regarding the commercially available fruit and vegetable cleaning machines, Wang Shiwen, director of the Ozone Professional Committee of the China Federation of Industrial Economics, said that the current fruit and vegetable cleaning machines on the market mainly use ozone to "sterilize and sterilize". Although ozone is effective in this aspect, it mostly refers to the "big ozone" with high quality and concentration. The antivirus and sterilization effects of a large ozone machine with a price of more than one million yuan cannot be achieved by small household ozone machines with limited ozone output and concentration. on a par. Wang Yanhong, director of the Agricultural Product Safety and Environmental Quality Monitoring Center of the Chinese Academy of Sciences, said that many years of experiments have proved that fruit and vegetable cleaning machines can indeed remove pesticides left on the surface of some fruits and vegetables, and the higher the ozone concentration, the better the detoxification effect, but the removal power of household machines is limited. 10% to 20% ("Beijing Youth Daily" December 26, 2010).

Contents of the invention

The purpose of the present invention is to provide an ultrasonic-photocatalytic coupling fruit and vegetable cleaning method.

The ultrasonic-photocatalytic coupling fruit and vegetable cleaning method provided by the invention comprises the following steps:

Add water to the cleaning box or inner tank of the fruit and vegetable cleaning device, place the fruits and vegetables to be cleaned on the porous pallet, and adjust the height of the porous pallet so that the fruits and vegetables to be cleaned are completely submerged in the water;

introducing oxygen and/or air into the inner tank through the porous supporting plate and generating a large number of air bubbles, so that the oxygen and/or air are fully dissolved in the water;

Turn on the ultrasonic generator;

The ultraviolet light source is turned on under the control of the controller, and the ultraviolet light emitted by the ultraviolet light source is emitted to the photocatalyst film of the inner tank through the light-transmitting window. radical OH· and negative oxygen ion radicals O ₂ ^- to oxidize and degrade pesticide residues on the surface of fruits and vegetables.

Preferably, the working frequency of the ultrasonic generator is 10-1000 kHz, and the sound intensity of the ultrasonic waves emitted by it is 1-100 W·cm ^-2 .

Preferably, the ultraviolet light emitted by the ultraviolet light source has a wavelength of 100-400nm.

Preferably, the oxygen and/or air is introduced from the air source into the inner container through the porous support plate through the air conduit, and the amount of oxygen and/or air introduced is 10-50 sccm.

Preferably, the temperature of the water in the cleaning tank or the inner tank is 20-50°C.

Preferably, the time required for the method to clean fruits and vegetables is 10-30 minutes.

Preferably, the height of the porous supporting plate is adjusted through an adjustable bracket.

Preferably, the oxygen and/or air introduced into the inner tank generates a large number of bubbles through the small holes and/or microporous aeration heads on the porous support plate.

Preferably, the power of the ultrasonic generator and the movement of the adjustable bracket are controlled by the controller.

The present invention has following beneficial effects:

(1) The method for cleaning fruits and vegetables does not require ozone, which eliminates the possible harm of ozone to the human body and the environment during use;

(2) Without adding any chemical cleaning agent, the fruit and vegetable cleaning method uses the synergistic effect of ultrasonic waves, photocatalysis and oxygen to achieve the purpose of degrading pesticide residues in fruits and vegetables, which not only improves the degradation efficiency of pesticide residues, but also effectively reduces The harm to the human body and the environment has been eliminated, and green cleaning has been realized;

(3) The fruit and vegetable cleaning method is not only applicable to the cleaning of a small amount of fruits and vegetables in the family, but also to the automatic and continuous cleaning of large quantities of fruits and vegetables;

(4) By adopting the method for cleaning fruits and vegetables, the degradation rate of pesticide residues on the surface of fruits and vegetables can reach 40%-70%.

Description of drawings

Fig. 1 is the schematic diagram of the cleaning box and its internal components of the ultrasonic-photocatalytic coupling fruit and vegetable cleaning device of embodiment 1 of the present invention;

Fig. 2 is a schematic diagram of a cleaning box and its internal components of an ultrasonic-photocatalytic coupled fruit and vegetable cleaning device according to Example 2 of the present invention.

Detailed ways

The content of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1

The fruit and vegetable cleaning device adopted in the present embodiment comprises a cleaning box 101, an inner container 102 with a light-transmitting window 105, four ultraviolet light sources 103, a porous supporting plate 104, an adjustable support 106, a microporous aeration head 107, an ultrasonic generator, Controller, air source, air duct, motor and radiator. The cleaning box 101 of the cleaning device and its internal components are shown in FIG. 1 . The cleaning box 101 is made of opaque material, and its shape is a cuboid with an open upper end. The volume of the cleaning tank 101 is 5-10L. In this embodiment, the volume of the cleaning tank 101 is, for example, 5L. The liner 102 is placed in the cleaning box 101 , with open upper and lower ends, and the liner 102 can be disassembled from the cleaning box 101 . The porous supporting plate 104 is located in the inner container 102 and can move up and down in the inner container 102 . The ultraviolet light source 103 is sealed and installed at the four corners of the cleaning box 101 by the isolation cover 108 , so that the water in the cleaning box 101 cannot enter the ultraviolet light source 103 . Each of the four corners of the cleaning box 101 is provided with a light-shielding cover for blocking the ultraviolet light emitted by the ultraviolet light source 103 and emitted upward. Light-transmitting windows 105 are respectively installed at four corners of the inner container 102 . The cleaning box 101, the inner tank 102 and the ultraviolet light source 103 are arranged so that the ultraviolet light emitted by the ultraviolet light source 103 can only pass through the isolation cover 108 and the light-transmitting window 105 to the In the liner 102. The inner wall of the liner 102 except the light-transmitting window 105 is covered with a photocatalyst film. In this embodiment, the transparent window 105 and the isolation cover 108 are made of, for example, quartz glass, and the photocatalyst film is made of, for example, titanium dioxide TiO ₂ film. The adjustable bracket 106 is located under the perforated support plate 104 and is used for adjusting the height of the perforated support plate 104 . The microporous aeration head 107 is installed on the porous supporting plate 104 . One end of the gas delivery conduit is connected to the gas source, and the other end is divided into two paths, one of which is placed under the porous support plate 104 and the other is connected to the microporous aeration head 107 . The gas delivery conduit is used to introduce, for example, oxygen from the gas source into the inner tank 102 through the small holes on the porous support plate 104 and/or the microporous aeration head 107 . The small holes on the porous support plate 104 and the microporous aeration head 107 are used to generate a large number of air bubbles, so that oxygen is fully dissolved in the water. The ultrasonic generator is used to provide ultrasonic waves for the cleaning device. The controller is used for controlling the power of the ultrasonic generator, turning on and off of each of the ultraviolet light sources 103 , and the movement of the adjustable bracket 106 . The electric motor is used to power the adjustable stand 106 . The radiator is used to reduce the temperature of the cleaning device during the cleaning process.

The ultrasonic-photocatalytic coupling fruit and vegetable cleaning method provided in this embodiment includes the following steps:

Add water to the cleaning box 101 of the fruit and vegetable cleaning device, place the fruits and vegetables to be cleaned on the porous pallet 104, adjust the height of the porous pallet 104 so that the fruits and vegetables to be cleaned are completely submerged in water;

For example, oxygen is introduced into the inner tank 102 through the porous supporting plate 104 and a large number of air bubbles are generated, so that the oxygen is fully dissolved in the water;

Turn on the ultrasonic generator;

The ultraviolet light source 103 is turned on under the control of the controller, and the ultraviolet light emitted by the ultraviolet light source 103 passes through the light-transmitting window 105 and exits onto the photocatalyst film of the inner tank 102. The synergistic effect of ultrasonic waves, photocatalysis and oxygen makes water produce A large number of hydroxyl radicals OH· and negative oxygen ion radicals O ₂ ^- can oxidize and degrade pesticide residues on the surface of fruits and vegetables.

When the ultraviolet light is emitted onto the photocatalyst film, the photocatalyst film absorbs the ultraviolet light and generates photogenerated electrons and photogenerated holes. The photogenerated holes oxidize water molecules or hydroxide ions on the surface of the catalyst film to form hydroxyl radicals OH·; the photogenerated electrons interact with oxygen in water to generate negative oxygen ion radicals O ₂ ^- . The hydroxyl radical OH· and the negative oxygen ion radical O ₂ ^- have strong oxidizing properties, and can oxidize and degrade pesticide residues into non-toxic and harmless substances such as small inorganic molecules, carbon dioxide and water. The cavitation of ultrasonic waves can not only accelerate the formation of the hydroxyl radical OH· and the negative oxygen ion radical O ₂ ^- , but also pyrolyze the pesticide residue.

The working frequency of the ultrasonic generator is 10-1000kHz, and the ultrasonic sound intensity emitted by it is 1-100W·cm ^-2 . The ultraviolet light emitted by the ultraviolet light source 103 has a wavelength of 100-400nm. For example, oxygen is introduced from a gas source through the porous support plate 104 into the inner tank 102 through the gas delivery conduit, and the amount of oxygen introduced is 10-50 sccm. The temperature of the water in the cleaning tank 101 is 20-50°C. The time required for the method to clean fruits and vegetables is 10-30 minutes. The height of the perforated tray 104 is adjusted by an adjustable bracket 106 . The adjustable stand 106 is powered by an electric motor. The oxygen introduced into the inner tank 102 generates a large number of bubbles through the small holes on the porous support plate 104 and/or the microporous aeration head 107 . The temperature of the fruit and vegetable cleaning device is lowered through a radiator. The power of the ultrasonic generator and the movement of the adjustable bracket 106 are controlled by the controller. After cleaning, the cleaned fruits and vegetables are removed from the perforated pallet 104 . By adopting the method for cleaning fruits and vegetables, the degradation rate of pesticide residues on the surface of fruits and vegetables can reach 40%-70%.

Example 2

The fruit and vegetable cleaning device adopted in this embodiment includes a cleaning box 201, an inner container 202 with a light-transmitting window 205, two ultraviolet light sources 203, a porous supporting plate 204, an adjustable support 206, a microporous aeration head 207, an ultrasonic generator, Controller, air source, air duct, motor and radiator. The cleaning box 201 of the cleaning device and its internal components are shown in FIG. 2 . The cleaning box 201 is made of opaque material, and its shape is cylindrical with an open upper end. The liner 202 is placed in the cleaning box 201 with an open upper end, and the liner 202 can be disassembled from the cleaning box 201 . The volume of the inner tank 202 is 5-10L. In this embodiment, the volume of the inner tank 202 is, for example, 10L. The porous supporting plate 204 is located in the inner container 202 and can move up and down in the inner container 202 . For example, the two ultraviolet light sources 203 are installed symmetrically between the cleaning box 201 and the inner tank 202 . A light-transmitting window 205 is installed on the side wall of the inner container 202 . The cleaning box 201 , the inner tank 202 and the ultraviolet light source 203 are arranged so that the ultraviolet light emitted by the ultraviolet light source 203 can only pass through the light-transmitting window 205 and exit into the inner tank 202 . Except for the transparent window 205, the inner wall of the liner 202 is covered with a photocatalyst film. In this embodiment, the transparent window 205 is made of, for example, quartz glass, and the photocatalyst film is made of, for example, a titanium dioxide TiO ₂ film. The adjustable bracket 206 is located below the perforated support plate 204 and is used for adjusting the height of the perforated support plate 204 . The microporous aeration head 207 is installed on the porous supporting plate 204 . One end of the gas delivery conduit is connected to the gas source, and the other end is divided into two paths, one of which is placed under the porous support plate 204 and the other is connected to the microporous aeration head 207 . The air delivery conduit is used to introduce, for example, air from the air source into the inner tank 202 through the small holes on the porous support plate 204 and/or the microporous aeration head 207 . The small holes on the porous support plate 204 and the microporous aeration head 207 are used to generate a large number of air bubbles, so that the oxygen in the air is fully dissolved in the water. The ultrasonic generator is used to provide ultrasonic waves for the cleaning device. The controller is used for controlling the power of the ultrasonic generator, turning on and off of each of the ultraviolet light sources 203 , and the movement of the adjustable bracket 206 . The electric motor is used to power the adjustable stand 206 . The radiator is used to reduce the temperature of the cleaning device during the cleaning process.

The ultrasonic-photocatalytic coupling fruit and vegetable cleaning method provided in this embodiment includes the following steps:

Adding water to the inner tank 202 of the fruit and vegetable cleaning device, placing the fruits and vegetables to be cleaned on the porous supporting plate 204, adjusting the height of the porous supporting plate 204 so that the fruits and vegetables to be cleaned are completely submerged in the water;

For example, air is introduced into the inner tank 202 through the porous supporting plate 204 and a large number of air bubbles are generated, so that the oxygen in the air is fully dissolved in the water;

Turn on the ultrasonic generator;

The ultraviolet light source 203 is turned on under the control of the controller, and the ultraviolet light emitted by the ultraviolet light source 203 passes through the light-transmitting window 205 and exits onto the photocatalyst film of the inner tank 202. A large number of hydroxyl radicals OH· and negative oxygen ion radicals O ₂ ^- can oxidize and degrade pesticide residues on the surface of fruits and vegetables.

When the ultraviolet light is emitted onto the photocatalyst film, the photocatalyst film absorbs the ultraviolet light and generates photogenerated electrons and photogenerated holes. The photogenerated holes oxidize water molecules or hydroxide ions on the surface of the catalyst film to form hydroxyl radicals OH·; the photogenerated electrons interact with oxygen in water to generate negative oxygen ion radicals O ₂ ^- . The hydroxyl radical OH· and the negative oxygen ion radical ·O ₂ ^- have strong oxidizing properties, and can oxidize and degrade pesticide residues into harmless substances such as small inorganic molecules, carbon dioxide and water. The cavitation of ultrasonic waves can not only accelerate the formation of the hydroxyl radical OH· and the negative oxygen ion radical O ₂ ^- , but also pyrolyze the pesticide residue.

The working frequency of the ultrasonic generator is 10-1000kHz, and the ultrasonic sound intensity emitted by it is 1-100W·cm ^-2 . For example, air is introduced from an air source through the porous support plate 204 into the inner container 202 through the air duct, and the air flow rate is 10-50 sccm. The ultraviolet light emitted by the ultraviolet light source 203 has a wavelength of 100-400nm. The temperature of the water in the inner tank 202 is 20-50°C. The time required for the method to clean fruits and vegetables is 10-30 minutes. The height of the perforated tray 204 is adjusted by an adjustable bracket 206 . The adjustable bracket 206 is powered by an electric motor. The air introduced into the inner tank 202 generates a large number of air bubbles through the small holes on the porous support plate 204 and/or the microporous aeration head 207 . The temperature of the fruit and vegetable cleaning device is lowered through a radiator. The power of the ultrasonic generator and the movement of the adjustable bracket 206 are controlled by the controller. After cleaning, the cleaned fruits and vegetables are removed from the perforated pallet 204 . By adopting the method for cleaning fruits and vegetables, the degradation rate of pesticide residues on the surface of fruits and vegetables can reach 40%-70%.

The fruit and vegetable cleaning method provided by the present invention is not only suitable for cleaning a small amount of fruits and vegetables at home, but also suitable for automatic and continuous cleaning of large quantities of fruits and vegetables.

It should be understood that the above detailed description of the technical solution of the present invention with the aid of preferred embodiments is illustrative rather than restrictive. Those skilled in the art can modify the technical solutions recorded in each embodiment on the basis of reading the description of the present invention, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the corresponding technical solutions Essentially deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (9)

1. ultrasonic wave-photocatalysis coupled fruits and vegetables cleaning method is characterized in that this method comprises the steps:

In the cleaning case (1) of fruits and vegetables cleaning device or inner bag (2), add entry, the fruits and vegetables that needs are cleaned are placed on the porous supporting plate (4), and the height of regulating said porous supporting plate (4) makes the fruits and vegetables that need to clean be immersed in the water fully;

In said porous supporting plate (4) is incorporated into said inner bag (2) and produce great amount of bubbles, make oxygen and/or air fully be dissolved in the water oxygen and/or air;

Open supersonic generator;

Ultraviolet source (3) is opened in control through controller; The ultraviolet light that said ultraviolet source (3) sends sees through light inlet window (5) and shines on the photocatalyst film of said inner bag (2), and the synergy of ultrasonic wave, photocatalysis and oxygen makes and produces a large amount of hydroxyl radical free radical OH and negative oxygen ion free radical O in the water ₂ ^-, so that the residues of pesticides oxidative degradation of fruit and vegetable surfaces.

2. ultrasonic wave according to claim 1-photocatalysis coupled fruits and vegetables cleaning method is characterized in that the operating frequency of said supersonic generator is 10-1000kHz, and the ultrasonic wave sound intensity that it sends is 1-100Wcm ^-2

3. ultrasonic wave according to claim 1-photocatalysis coupled fruits and vegetables cleaning method is characterized in that the ultraviolet light wavelength that said ultraviolet source (3) sends is 100-400nm.

4. ultrasonic wave according to claim 1-photocatalysis coupled fruits and vegetables cleaning method; It is characterized in that; Through the gas transmission conduit with oxygen and/or air from source of the gas in said porous supporting plate (4) is incorporated into said inner bag (2), the feeding amount of oxygen and/or air is 10-50sccm.

5. ultrasonic wave according to claim 1-photocatalysis coupled fruits and vegetables cleaning method is characterized in that, the temperature of water is 20-50 ℃ in said cleaning case (1) or the said inner bag (2).

6. ultrasonic wave according to claim 1-photocatalysis coupled fruits and vegetables cleaning method is characterized in that, the time that said method is cleaned fruits and vegetables to be needed is 10-30 minute.

7. ultrasonic wave according to claim 1-photocatalysis coupled fruits and vegetables cleaning method is characterized in that, regulates the height of said porous supporting plate (4) through adjustable support (6).

8. ultrasonic wave according to claim 1-photocatalysis coupled fruits and vegetables cleaning method is characterized in that, makes the oxygen and/or the air that are incorporated in the said inner bag (2) produce a large amount of bubbles through aperture on the said porous supporting plate (4) and/or micro porous aeration head (7).

9. ultrasonic wave according to claim 1-photocatalysis coupled fruits and vegetables cleaning method is characterized in that, controls the motion of the power and the said adjustable support (6) of said supersonic generator through said controller.

Images