Device and method for degrading paralytic saxitoxin through plasma discharge

Abstract

The invention discloses a device and method for degrading paralytic saxitoxin through plasma discharge, and belongs to the technical field of plasmas, the device comprises a container, a reactor, a high-voltage pulse power supply and an air pump; an electric field, ultraviolet radiation and high-activity RO (N) S generated in the plasma generation process through gas ionization can comprehensively act on toxic groups of toxins, effective plasma dosage is kept, the mother nucleus structure of the toxins can be destroyed, steady-state free radicals are generated, and finally low-toxicity or non-toxic products are formed. The method has the advantages of being good in effect, short in period, low in temperature, free of residues, free of secondary pollution and the like, and can be applied to paralytic saxitoxin degradation.

Description

Technical Field

[0001] The invention belongs to the field of plasma technology, and in particular relates to a device and method for degrading paralytic shellfish toxins by plasma discharge. Background Art

[0002] Paralytic shellfish toxins (PSTs) are natural neurotoxins produced by some dinoflagellates in the marine environment. They are the most widely distributed, most harmful, and most accident-prone type of algal toxins in the world. They have strong neurotoxicity and are easily highly accumulated and persist for a long time in vector organisms such as fish, shrimp, and shellfish. They are then transmitted and accumulated step by step through the food chain, and finally transferred into humans and animals, posing a serious threat to human health.

[0003] PSTs is a general term for a class of tetrahydropurine tricyclic toxins with complex and diverse structures and a wide variety of species. According to the different substituents, they can be divided into four categories, including carbamates, decarbamoyls, N-sulfonamide carbamoyls and deoxydecarbamoyls. Gonyautoxin 1 (GTX1) and Gonyautoxin 4 (GTX4) belong to the carbamate PSTs with strong toxicity; Gonyautoxin 6 (GTX6) belongs to the N-sulfonamide carbamoyl PSTs with moderate toxicity. PSTs can be absorbed through the digestive tract and flow through the blood to various tissues and organs of organisms to exert toxic effects. The toxic mechanism in the body is basically similar. PSTs poisoning can cause an increase in the level of reactive oxygen in cells, induce cellular oxidative stress, lead to oxidative damage to biological molecules such as DNA, proteins and lipids, and cause severe cytotoxicity; at the same time, through the functional groups carried by themselves, they reversibly bind to the Na+ channels on the membranes of nerve and muscle cells, block the Na+ channels, destroy normal depolarization, and cause an imbalance in the distribution of ions inside and outside the cells, affecting the normal conduction of nerve signals and muscle contraction, thereby producing neurotoxicity. The color, smell and taste of fish, shrimp and shellfish contaminated by PSTs are normal, and cannot be removed through processing. In the early stage of human poisoning, people will feel nausea, vomiting, and numbness of the mouth, tongue and lips, and then the numbness will slowly spread to the face, neck and limbs. In severe cases, it will cause difficulty in exhaling, paralysis of muscles throughout the body and even death. PSTs contamination of fish, shrimp and shellfish will not only cause great economic losses, but also pose a serious threat to food safety. Nearly 2,000 cases of PSTs poisoning occur worldwide each year, of which the mortality rate of humans is as high as 15%. Up to now, the degradation method of PSTs is not yet mature, so it is particularly important to carry out research on green, safe and efficient PSTs degradation technology.

[0004] Plasma is the fourth state of matter besides solid, liquid and gas, and can be generated by gas discharge. The principle is to apply a strong electric field to the air so that electrons gain energy and break free from the constraints of gas atoms or molecules, resulting in field ionization; these electrons, as seed electrons, collide with gas molecules under the action of strong electric field force, resulting in collision ionization; the newly generated free electrons are continuously accelerated under the action of electric field force and collide with other gas molecules. This process occurs cyclically, forming an electron avalanche and eventually generating plasma. The main components of plasma include charged particles (electrons, positive and negative ions), excited particles (excited atoms, molecules), free radicals (OH •, etc.) and active nitrogen and oxygen substances RO(N)S, etc., which have high chemical activity and are applied in energy, environment, materials, food, medical and other fields. Previous studies have found that low-temperature plasma can be used to degrade fungal toxins in food. The electric field, ultraviolet radiation and highly active RO(N)S generated during the gas ionization process to produce plasma can act comprehensively on the toxic groups of the toxins while maintaining an effective plasma dose. It can destroy the toxin parent nucleus structure, produce steady-state free radicals, and ultimately form low-toxic or non-toxic products. It has many advantages such as good effect, short cycle, low temperature, no residue, and no secondary pollution, and can be applied to PSTs degradation research. Summary of the invention

[0005] In view of the technical problems raised in the background technology, the present invention proposes a device and method for degrading paralytic shellfish toxins by plasma discharge.

[0006] The present invention is achieved through the following technical solutions:

[0007] A device for degrading paralytic shellfish toxins by plasma discharge, comprising a container, a reactor, a high-voltage pulse power supply and an air pump;

[0008] The reactor comprises an inner cylinder and an outer cylinder, a reaction chamber is formed between the inner cylinder and the outer cylinder, a part of the cylinder wall of the outer cylinder forms a mesh grid, the reactor is arranged in a container, the mesh grid part is immersed in the reaction liquid in the container, the high-voltage pulse power supply is connected to the reaction chamber of the reactor through a voltage line, and the air pump is connected to the reaction chamber of the reactor through an air inlet pipe.

[0009] In the above technical solution, the reactor also includes a flange and fixing rods for fixing. The number of flanges is 2, and the number of fixing rods is 5. The flanges are arranged on both sides of the reactor, and the fixing rods are evenly distributed around the reactor along the circumference. The two sides are connected through the through holes on the flanges and fixed by nuts.

[0010] In the above technical solution, a metal ring is arranged outside the grid portion of the reactor, and the metal ring is grounded through a wire.

[0011] In the above technical solution, the device also includes an oscilloscope, which is connected to a voltage probe and a current detection coil. The voltage probe is connected to a voltage line of a high-voltage pulse power supply and is grounded, and the wire of the metal ring passes through the current detection coil.

[0012] In the above technical solution, the pulse width of the high-voltage pulse power supply is 100 ns, the voltage is 12 kV, and the frequency is 2 kHz.

[0013] A method for degrading paralytic shellfish toxins by plasma discharge, comprising the following steps:

[0014] Step 1, placing a reaction liquid containing paralytic shellfish toxin in a container, turning on an air pump, and immersing a grid portion of the reactor in the reaction liquid in the container;

[0015] Step 2, turning on the air pump to introduce air into the reaction chamber of the reactor;

[0016] Step 3, set the high voltage pulse power supply pulse width, voltage, frequency and reaction time, and start the reaction;

[0017] Step 4: Turn off the high-voltage pulse power supply, take out the reactor, turn off the air pump, and complete the reaction.

[0018] In the above technical solution, the pulse width of the high-voltage pulse power supply is 100 ns, the voltage is 12 kV, the frequency is 2 kHz, and the response time is 1-10 min.

[0019] In the above technical solution, the reaction time is preferably 1 min, 5 min or 10 min.

[0020] Beneficial effects:

[0021] The present invention selects low-temperature plasma treatment as the core technology, and applies the generated low-temperature plasma to the degradation of paralytic shellfish toxins, thereby reducing the concentration of toxins and weakening their toxic effects. This provides a new path and scientific basis for building green, safe and efficient technology to degrade PSTs from the ocean. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a schematic diagram of the structure of a device for degrading paralytic shellfish toxins by plasma discharge.

[0023] Figure 2 It is a schematic diagram of the local structure of the reactor in the present invention.

[0024] Figure 3 It is a schematic diagram of the cross-sectional structure of the reactor in the present invention.

[0025] Figure 4The effect of low-temperature plasma treatment on the concentrations of GTX1, 4, and 6 in PSTs solution at different degradation times.

[0026] Figure 5 Effects of GTX1, 4, and 6 on zebrafish mortality before and after plasma treatment.

[0027] Figure 6 This is the effect of GTX1, 4, and 6 on the hatching rate of zebrafish before and after plasma treatment.

[0028] Among them: 1 is a high-voltage pulse power supply, 2 is an oscilloscope, 3 is a voltage probe, 4 is a reactor, 5 is a current detection coil, 6 is an air pump, 7 is an air inlet pipe, 8 is a voltage line, 9 is a fixing rod, 10 is a flange, 11 is a metal ring, 12 is a grid, 13 is a container, 14 is a reaction liquid, 15 is an inner cylinder, 16 is an outer cylinder, and 17 is a reaction chamber. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. However, the following embodiments are limited to explaining the present invention, and the protection scope of the present invention should include the entire contents of the claims, and through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0030] Example 1 A device for degrading paralytic shellfish toxins by plasma discharge

[0031] like Figure 1 , Figure 2 and Figure 3 As shown, a device for degrading paralytic shellfish toxins by plasma discharge includes a container 13, a reactor 4, a high-voltage pulse power supply 1 and an air pump 6;

[0032] The reactor 4 includes an inner tube 15 and an outer tube 16, a reaction chamber 17 is formed between the inner tube 15 and the outer tube 16, a part of the tube wall of the outer tube 16 forms a mesh 12, the reactor 4 is arranged in a container 13, the mesh part is immersed in the reaction liquid 14 in the container 13, the high-voltage pulse power supply 1 is connected to the voltage line 8, the voltage line 8 is connected to the reaction chamber 17 of the reactor 4 through a stainless steel pipe, and the air pump 6 is connected to the reaction chamber 17 of the reactor 4 through an air inlet pipe 7.

[0033] In this embodiment, the reactor 4 also includes a flange 10 and a fixing rod 9 for fixing. The number of flanges 10 is 2, and the number of fixing rods 9 is 5. The flanges 10 are arranged on both sides of the reactor 4, and the fixing rods 9 are evenly distributed around the reactor 4 along the circumference. The two sides are connected through the through holes on the flange 10 and fixed by nuts; a metal ring 11 is arranged on the outside of the grid 12 of the reactor 4, and the metal ring 11 is grounded through a wire; the device also includes an oscilloscope 2, the oscilloscope 2 is connected to a voltage probe 3 and a current detection coil 5, the voltage probe 3 is connected to the voltage line 8 of the high-voltage pulse power supply 1 and is grounded, and the wire of the metal ring 11 passes through the current detection coil 5.

[0034] Example 2 A method for degrading paralytic shellfish toxins by plasma discharge

[0035] Methods: A high-voltage pulse power supply was used to discharge a large amount of RO(N)S and ultraviolet radiation to act on the PSTs extract through the plasma reactor. The relative contents and degradation efficiency of GTX1, GTX4 and GTX6 in the PSTs extract were detected by high-performance liquid chromatography, and the developmental toxicity changes were detected by zebrafish test.

[0036] Instruments and reagents: high-voltage pulse power supply (Xi'an Lingfengyuan Electronic Technology Co., Ltd.), plasma reactor, air pump, high-voltage probe, current probe, oscilloscope, 100 mL of paralytic shellfish toxin extract (the concentrations of GTX1, GTX4, and GTX6 in the original solution are 2413.321 ng / mL, 1663.981 ng / mL, and 330.350 ng / mL, respectively), 50 mL centrifuge tube, 15 mL centrifuge tube, Millex-GP filter (0.22 µm, 33 mm), 100 mL beaker, and purified water.

[0037] Experimental steps:

[0038] 1. Material handling

[0039] Take 20 mL of PSTs extract, dilute it 10 times, and take 30 mL of the diluted PSTs solution in a beaker each time for PSTs plasma discharge degradation treatment. The treatment time is set to 1 min (short time), 5 min (medium time), and 10 min (long time).

[0040] 2. Plasma degradation treatment

[0041] The discharge device consists of a power supply, a gas supply system, a plasma reactor and an electrical measurement system. The power supply in this study uses a high-voltage pulse power supply, which can generate repeated pulses with a rise and fall time of 50 ns and a pulse width of 100 ns. During the test, the voltage is fixed at 12 kV and the frequency is 2 kHz. The gas supply system consists of a hose that directly connects the air pump to the reactor, and the air enters the plasma reactor along the hose for ionization. The reactor structure is as follows Figure 2 As shown in the figure, it is composed of two nested cylindrical structures of different sizes. The inner and outer electrodes are made of quartz. The discharge occurs between the two electrodes, and the electrode gap is fixed at 2 mm. The air pump injects air into the ionization zone between the two electrodes through the air inlet. Under the action of the strong electric field, the gas molecules or atoms in the air are ionized into charged particles, excited ions, free radicals or RO(N)S, etc., and then the air is blown out into the PSTs solution through the small holes densely distributed under the outer electrode. The reactor is fixed on a stainless steel tube, which is connected to the output end of a high-voltage pulse power supply as a high-voltage electrode. The grid of the reactor is partially grounded as a grounding electrode. During the test, the voltage and current waveforms are measured by an oscilloscope.

[0042] 3. Degradation rate verification

[0043] Referring to the national standard GB 5009.213-2016 "National Food Safety Standard Determination of Paralytic Shellfish Toxins in Shellfish", the high performance liquid chromatography method was used to determine the concentrations of GTX1, GTX4, and GTX6 toxins in the PSTs solution and determine their degradation rates.

[0044] 4. Biological effect verification

[0045] Wild-type zebrafish were raised in the Aisheng zebrafish breeding system. Males and females (at a ratio of 2:1) were placed on both sides of the mating box the night before the experiment. The partition in the middle of the mating box was removed after light was applied on the morning of the experiment. After 1 hour, the eggs were collected and the dead and broken eggs were discarded. 20 fertilized eggs were placed in PSTs solution without plasma treatment and after plasma treatment for 10 minutes for biological effect verification. The effect of plasma treatment on the developmental toxicity of GTX1, GTX4, and GTX6 was analyzed by the mortality rate and hatching rate of zebrafish after a certain period of breeding.

[0046] In the zebrafish experiment, a plasma-untreated group and a plasma-treated group were set up. The mortality rate of zebrafish at 24 h, 48 h, 72 h, and 96 h after administration and the hatching rate at 48 h, 72 h, and 96 h were counted at different test substance concentrations. The changes in the developmental toxicity of GTX1, GTX4, and GTX6 on zebrafish after 10 min of plasma treatment were analyzed.

[0047] result

[0048] 1. Plasma degradation test results

[0049] The results of low temperature plasma degradation of paralytic shellfish toxins GTX1, GTX4, and GTX6 are shown in Table 1 and Figure 4 As shown in the figure, when treated for 1 min, the concentrations of GTX1 and GTX6 decreased, and the concentration of GTX4 increased slightly; when treated for 5 min, the concentrations of the three paralytic shellfish toxins decreased by nearly 10%; the degradation effect was best when treated for 10 min, and the concentrations of GTX1, GTX4, and GTX6 decreased by 55.33%, 77.2%, and 65.06%, respectively. At this time, the concentrations of the three toxins in the PSTs solution were 133.53 ng / mL, 128.46 ng / mL, and 21.50 ng / mL, respectively. Therefore, low-temperature plasma can significantly reduce the concentrations of GTX1, GTX4, and GTX6 in the PSTs solution.

[0050] Table 1 Effect of low-temperature plasma treatment on the concentrations of GTX1, 4, and 6 in PSTs solution at different degradation times

[0051] 2. Biological validation test results

[0052] The results of the zebrafish experiment are shown in Table 2 below. The mortality rate of zebrafish fed with the PSTs solution in the group without plasma treatment increased in a time-dependent and concentration-dependent manner, and its median lethal concentration LC50 = 70.02 ng / mL; while the developmental toxicity of the same concentration of PSTs solution to zebrafish was significantly weakened after plasma treatment, LC50 = 119.49 ng / mL, and the mortality rate was significantly lower than that of the group without plasma treatment. The results of the zebrafish hatching rate are shown in Table 3 below. No zebrafish in the two groups hatched 48 hours after administration. The hatching rates at 72 hours and 96 hours after administration were 70.59% and 94.12%, respectively, which were significantly higher than 0% and 46.67% in the group without plasma treatment. Therefore, the degradation effect is best when the plasma treatment is 10 minutes. The experimental data are shown in Table 3. Figure 5 , Figure 6 shown.

[0053] Table 2 Effects of PSTs solution on zebrafish mortality before and after plasma treatment (concentration in GTX1)

[0054] Table 3 Effects of PSTs solution before and after plasma treatment on the hatching rate of zebrafish

[0055] in conclusion:

[0056] The experimental results show that:

[0057] (1) The best effect was achieved when low-temperature plasma was used to treat paralytic shellfish toxins GTX1, GTX4, and GTX6 for 10 min, and the toxin concentration decreased in a time-dependent manner.

[0058] (2) The results of the zebrafish experiment showed that plasma treatment for 10 min could significantly reduce the developmental toxicity of paralytic shellfish toxins GTX1, GTX4, and GTX6 to zebrafish.

[0059] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A device for degrading paralytic shellfish toxins by plasma discharge, characterized in that: It includes a container, a reactor, a high-voltage pulse power supply and an air pump; The reactor comprises an inner cylinder and an outer cylinder, a reaction chamber is formed between the inner cylinder and the outer cylinder, a part of the cylinder wall of the outer cylinder forms a mesh grid, the reactor is arranged in a container, the mesh grid part is immersed in the reaction liquid in the container, the high-voltage pulse power supply is connected to the reaction chamber of the reactor through a voltage line, and the air pump is connected to the reaction chamber of the reactor through an air inlet pipe.

2. The device for degrading paralytic shellfish toxins by plasma discharge according to claim 1, characterized in that: The reactor also includes a flange and a fixing rod for fixing. The number of flanges is 2 and the number of fixing rods is 5. The flanges are arranged on both sides of the reactor. The fixing rods are evenly distributed around the reactor along the circumference. The two sides are connected through the through holes on the flanges and fixed by nuts.

3. The device for degrading paralytic shellfish toxins by plasma discharge according to claim 1, characterized in that: A metal ring is arranged outside the grid portion of the reactor, and the metal ring is grounded through a wire.

4. The device for degrading paralytic shellfish toxins by plasma discharge according to claim 3, characterized in that: The device also includes an oscilloscope, which is connected to a voltage probe and a current detection coil. The voltage probe is connected to a voltage line of a high-voltage pulse power supply and is grounded. The wire of the metal ring passes through the current detection coil.

5. The device for degrading paralytic shellfish toxins by plasma discharge according to claim 1, characterized in that: The high-voltage pulse power supply has a pulse width of 100 ns, a voltage of 12 kV, and a frequency of 2 kHz.

6. A method for degrading paralytic shellfish toxins by plasma discharge, characterized in that: The steps include: Step 1, placing a reaction liquid containing paralytic shellfish toxins in a container, turning on an air pump, and immersing a grid portion of the reactor in the reaction liquid in the container; Step 2, turning on the air pump to introduce air into the reaction chamber of the reactor; Step 3, set the high voltage pulse power supply pulse width, voltage, frequency and reaction time, and start the reaction; Step 4: Turn off the high-voltage pulse power supply, take out the reactor, turn off the air pump, and complete the reaction.

7. The method for degrading paralytic shellfish toxins by plasma discharge according to claim 6, characterized in that: The high-voltage pulse power supply has a pulse width of 100 ns, a voltage of 12 kV, a frequency of 2 kHz, and a reaction time of 1-10 min.

8. The method for degrading paralytic shellfish toxins by plasma discharge according to claim 6, characterized in that: The reaction time is 1 min, 5 min or 10 min.

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