Method and device for microfluidically oxidizing thiosulfate

Abstract

The invention provides a method and a device for microfluid oxidation of thiosulfate, which are characterized in that microfluid oxidation thiosulfate generates oxygen micro-nano bubbles with uniform size through a microfluid device, and the oxygen micro-nano bubbles and a thiosulfate solution are subjected to oxidation reaction under an acidic condition (pH = 1-3); the oxidation efficiency is remarkably improved by utilizing the effect of increasing the generation amount of hydroxyl free radicals in a low-pH environment and synergistically enhancing microbubbles. The method is easy and convenient to operate and mild in reaction condition, the highest oxidation rate can reach 99%, and the method is suitable for efficient treatment and resource recycling of the sulfur-containing wastewater and has the advantages of being low in cost, high in efficiency, environmentally friendly and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thiosulfate treatment, and particularly relates to a method and device for microfluidic oxidation of thiosulfate. BACKGROUND

[0002] As a common sulfur-containing compound, thiosulfate is widely present in wastewater from mineral processing, gold smelting, organic synthesis, and coking industries, and its potential harm to the environment cannot be ignored. In the natural environment, thiosulfate can be oxidized and decomposed to generate elemental sulfur and sulfate, or produce toxic hydrogen sulfide under anaerobic conditions. Therefore, it is of great environmental significance to develop efficient and environmentally friendly thiosulfate oxidation treatment technologies. The basic process of thiosulfate oxidation reaction can be represented as: The current common thiosulfate treatment methods include chemical oxidation method, biological oxidation method, and advanced oxidation process. The traditional chemical oxidation method requires adding a large amount of chemical agent, which is high in cost and easy to cause secondary pollution; the biological oxidation method is relatively environmentally friendly, but has low treatment efficiency and poor running stability; the advanced oxidation technology (such as Fenton method, UV / H2O2, etc.) has high efficiency, but the equipment is complex and the running cost is high. Therefore, there is an urgent practical need to develop an efficient, economical, and environmentally friendly thiosulfate oxidation treatment technology. SUMMARY

[0003] To solve the technical problems of low thiosulfate treatment efficiency, high running cost, and environmental pollution in the above common technologies, the present application provides a method for microfluidic oxidation of thiosulfate, comprising the steps of: Generating oxygen micro-nano bubbles by using a microfluidic device, the oxygen micro-nano bubbles and the thiosulfate solution undergo an oxidation reaction to generate oxidation products; and controlling the oxidation reaction to be carried out under the condition that the pH is 0.5-3.

[0004] Further, the size of the oxygen micro-nano bubbles is 800-1700 nanometers.

[0005] Further, the size of the oxygen micro-nano bubbles is 1000-1600 nanometers.

[0006] Further, the microfluidic device comprises a microfluidic chip assembly and / or a three-way connection PTFE pipeline assembly.

[0007] Further, the microfluidic device comprises: A feeding unit comprising a liquid inlet pipe for feeding the thiosulfate solution and a gas inlet pipe for feeding oxygen. The reaction collecting unit comprises a connecting device and a collecting pipe; the connecting device connects the liquid inlet pipe and the gas inlet pipe as a confluence point, and the collecting pipe is connected downstream of the connecting device. The thiosulfate solution and oxygen converge at the connecting device to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the reaction product is collected by the collecting pipe.

[0008] Further, the connecting device of the three-way PTFE pipe assembly is a PTFE guide pipe with an inner diameter of 1-1.2 mm; and the connecting device of the microfluidic chip assembly is a microfluidic chip.

[0009] Further, the liquid phase input flow rate of the liquid inlet pipe is 0.8-2.5 mL / min, and the gas phase input flow rate of the gas inlet pipe is 0.5-2.5 mL / min.

[0010] Further, the liquid phase input flow rate of the liquid inlet pipe is 0.5-2 mL / min, and the gas phase input flow rate of the gas inlet pipe is 1-2 mL / min.

[0011] Further, the internal channel of the microfluidic chip has a depth of 50-150 um and a width of 400-600 um.

[0012] The present application provides a microfluidic device comprising a feeding unit and a reaction collecting unit. The feeding unit comprises a liquid inlet pipe for introducing a thiosulfate solution and a gas inlet pipe for introducing oxygen. The reaction collecting unit comprises a connecting device and a collecting pipe; the connecting device connects the liquid inlet pipe and the gas inlet pipe as a confluence point, and the collecting pipe is connected downstream of the connecting device. The thiosulfate solution and oxygen converge at the connecting device to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the reaction product is collected by the collecting pipe.

[0013] Compared with the prior art, the present application has at least the following advantages: The present application focuses on the technical problems in the field of thiosulfate treatment, such as low treatment efficiency, high operating cost and possible environmental pollution, and innovatively provides a method for oxidizing thiosulfate based on microfluidic technology.

[0014] Microfluidic technology has the unique advantage of precisely manipulating fluid behavior at the micro-nano scale, enabling precise control of microbubble size, quantity, and composition. By utilizing this feature, combined with the high specific surface area, high internal pressure, and special surface charge distribution of microbubbles, a special interfacial reaction environment can be created, significantly and controllably improving gas-liquid mass transfer efficiency, laying a solid foundation for efficient oxidation of thiosulfate.

[0015] The mechanism of the method for oxidizing thiosulfate by microbubbles of the application is as follows: uniform-sized oxygen micro-nano bubbles are generated by a microfluidic device, and an oxidation reaction occurs between the bubbles and a thiosulfate solution. Under low pH conditions, the amount of hydroxyl radicals generated is significantly increased, and microbubbles can further promote their generation, and the synergistic effect of the two greatly improves the oxidation efficiency, with an oxidation rate of up to 99% under optimal conditions.

[0016] From the technical effect, the application significantly improves the treatment efficiency of thiosulfate. By precisely controlling the reaction process through microfluidic technology, the reaction time is greatly shortened, and rapid and efficient oxidation treatment is achieved. In terms of operating cost, due to the improvement of reaction efficiency, energy consumption and the amount of reagents are reduced, effectively reducing the overall operating cost. At the same time, the application uses efficient oxidation reaction, which can fully convert thiosulfate into harmless or easily treated products, reducing waste emissions and environmental pollution, and has good environmental friendliness. In summary, the application performs well in solving the technical problem of thiosulfate treatment, and has significant application value and promotion prospects. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from the structures shown in the drawings without creative labor.

[0018] Figure 1 The oxidation rate of thiosulfate in the microfluidic system under different pH conditions in the analysis example 1 of the application is analyzed.

[0019] Figure 2 The oxidation rate of thiosulfate in the microfluidic system under different bubble size conditions in the analysis example 2 of the application is analyzed.

[0020] Figure 3 The XRD pattern of the oxidation product in the example 6 and the comparative example 3 of the application is analyzed.

[0021] Figure 4It is a structural schematic diagram of a microfluidic chip in an embodiment of the present application; wherein 1 is a main channel inlet, 2 is a side channel inlet, and 3 is a microfluidic chip outlet.

[0022] Figure 5 It is a structural schematic diagram of a microfluidic chip in an embodiment of the present application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0024] In addition, the technical solutions in the various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it. When the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the protection scope of the present application.

[0025] When the embodiments give numerical ranges, it should be understood that, unless otherwise stated by the present application, each numerical range has two endpoints and any number between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application are consistent with the mastery of the prior art by those skilled in the art and the description of the present application. Any method, equipment and material of the prior art similar or equivalent to the method, equipment and material in the embodiments of the present application can also be used to realize the present application.

[0026] The present application provides a method for microfluidic oxidation of thiosulfate, comprising the steps of: The microfluidic device is used to generate oxygen micro-nano bubbles, which have an oxidation reaction with a thiosulfate solution to generate an oxidation product; and the oxidation reaction is controlled to be carried out under the condition that the pH is 0.5-3.

[0027] In the present application, the concentration of thiosulfate in the thiosulfate solution can be 10-50 g / L. In some specific embodiments, the concentration of thiosulfate in the thiosulfate solution can be 15-40 g / L, such as 15-35 g / L or 20-35 g / L.

[0028] In the experimental cases of the present application, the thiosulfate solution is specifically a sodium thiosulfate solution; therefore, the thiosulfate solution of the present application can include sodium thiosulfate.

[0029] The present application innovatively performs the oxidation reaction under the condition that the pH is 0.5-3. In some embodiments, the pH of the thiosulfate solution can be controlled to be 0.5-3 to achieve pH control during the oxidation reaction process.

[0030] It should be noted that the pH of the oxidation reaction refers to the initial pH of the thiosulfate solution.

[0031] For example, the pH of the oxidation reaction can be controlled to be 0.5-3; the applicant has innovatively found that when the pH of the oxidation reaction is 0.5-3 and the size of the gas bubbles is not greater than 2000 nanometers, the oxidation rate of the thiosulfate is not less than 80%.

[0032] For another example, the pH of the oxidation reaction can be controlled to be 0.5-2.5; the applicant has innovatively found that when the pH of the oxidation reaction is 0.5-2.5 and the size of the gas bubbles is not greater than 2000 nanometers, the oxidation rate of the thiosulfate is not less than 85%.

[0033] For another example, the pH of the oxidation reaction can be controlled to be 0.5-2.5; the applicant has innovatively found that when the pH of the oxidation reaction is 0.5-2.5 and the size of the gas bubbles is not greater than 2000 nanometers, the oxidation rate of the thiosulfate is not less than 85%.

[0034] For another example, the pH of the oxidation reaction can be controlled to be 0.5-2.5; the applicant has innovatively found that when the pH of the oxidation reaction is 0.5-2.5 and the size of the gas bubbles is not greater than 2000 nanometers, the oxidation rate of the thiosulfate is not less than 85%.

[0035] In the present application, the microfluidic device can be a microfluidic chip assembly and / or a three-way connection PTFE pipeline assembly.

[0036] In some embodiments, the microfluidic device comprises: a feeding unit comprising a liquid inlet pipe for feeding the thiosulfate solution and a gas inlet pipe for feeding oxygen; a reaction collection unit comprising a connection device and a collection pipe; the connection device connects the liquid inlet pipe and the gas inlet pipe as a confluence point, and the collection pipe is connected downstream of the connection device; wherein the thiosulfate solution and the oxygen converge at the connection device to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the resulting reaction product is collected by the collection pipe.

[0037] In some embodiments, the connection device of the three-way connection PTFE pipeline assembly can be a PTFE conduit with an inner diameter of 1-1.2 mm; and the connection device of the microfluidic chip assembly can be a microfluidic chip.

[0038] In some embodiments, as shown in Figure 4 The microfluidic chip can be a T-shaped microfluidic chip, which is made of PDMS (polydimethylsiloxane) by soft lithography process and is single-sidedly bonded with a glass plate to form a closed microchannel network. The channel depth in the chip can be 50-150 μm, and the width can be 400-600 μm, and the channel size is uniform. The T-shaped structure includes a main channel and a vertically connected side channel, and the vertical side channel is used for shearing gas to generate oxygen micro-nano bubbles with uniform size. A serpentine channel is connected after the intersection to provide longer contact and mixing time for the fluid, effectively promoting the mixing between the reactants.

[0039] In the formula, 1 is the main channel inlet, which can be connected to the gas inlet pipe in the feeding unit; 2 is the side channel inlet, which can be connected to the liquid inlet pipe in the feeding unit; and 3 is the microfluidic chip outlet, which can be connected to the collection pipe.

[0040] For example, the length and spacing of the channels in the microfluidic chip can be as shown in Figure 5

[0041] For example, the channel depth of the microfluidic chip can be 80-120 um, such as 90-110 um; and the channel width of the microfluidic chip can be 450-600 um, such as 450-550 um.

[0042] In the present application, the size of the oxygen micro-nano bubbles is 800-1700 nm.

[0043] In some specific embodiments, the size of the oxygen micro-nano bubbles can be 1000-1600 nm.

[0044] Applicants have found the relationship between the bubble size and the oxidation rate of thiosulfate (under the condition that the pH is 0.5-1.5) through research: For example, the present application can control the bubble size to be 800-1700 nm, and in this case, the oxidation rate of thiosulfate is in the range of 98%-100%.

[0045] For example, when the bubble size is 1000-1600 nm, the oxidation rate of thiosulfate is in the range of 98.5%-100%.

[0046] ​It is particularly important to note that when the bubble size exceeds the specific range of 800-1700 nm, the oxidation effect of thiosulfate will decrease. If the bubble size is too small, although the theoretical gas-liquid contact area increases, in the actual reaction system, the effective contact and reaction of oxygen with thiosulfate solution may be affected due to factors such as bubble agglomeration and poor stability; when the bubble size is too large, the gas-liquid contact area is relatively reduced, the mass transfer efficiency is reduced, and the oxidation reaction is also difficult to proceed efficiently.

[0047] This finding is contrary to conventional wisdom. In common techniques, it is taken for granted that in microfluidic technology, below a certain lower limit of bubble size (such as 300 nanometers), the smaller the bubble size, the larger the gas-liquid contact area, the higher the mass transfer efficiency, and the higher the oxidation rate. However, the research results of the present application have powerfully shown with detailed experimental data that within a specific pH range (0.5-1.5), the oxidation rate is not higher the smaller the bubble size, and only when the bubble size is within the range of 800-1700 nanometers, can thiosulfate achieve relatively complete oxidation, maintaining the thiosulfate oxidation rate above 98%.

[0048] The applicant emphasizes that even in the case where the oxidation rate is already at a relatively high level (such as above 98%), the present application is still significantly creative in terms of subtle optimization of the oxidation rate (such as from 98% to 98.5% or even higher). In the fields of industrial production and environmental treatment, the treatment of thiosulfate often needs to be carried out on a large scale and for a long time, and even a subtle increase in oxidation rate means that more thiosulfate can be treated under the same time and resource input, reducing the amount of untreated or insufficiently treated, thereby reducing the potential threat to the environment. At the same time, from the perspective of economic benefits, the increase in oxidation rate can reduce the cost of reagents, energy and other costs required in the treatment process, and improve the overall treatment efficiency and economic benefits. This finding breaks the shackles of traditional thinking, providing a new theoretical basis and operational direction for microfluidic thiosulfate oxidation technology, fully embodying the creativity of the present application in theoretical research and technical application.

[0049] It should be noted that the present application controls the flow rates of liquid and gas phases to achieve the size control of oxygen micro-nano bubbles.

[0050] For example, the liquid phase input flow rate of the liquid inlet pipe can be 0.8-2.5 mL / min, and the gas phase input flow rate of the gas inlet pipe can be 0.5-2.5 mL / min.

[0051] For another example, the liquid phase input flow rate of the liquid inlet pipe can be 0.5-2 mL / min, and the gas phase input flow rate of the gas inlet pipe can be 1-2 mL / min.

[0052] For example, the liquid phase input flow rate of the liquid inlet tube can be 0.5-1.5 mL / min, such as 0.8-1.5 mL / min or 0.5-1.2 mL / min, and the gas phase input flow rate of the gas inlet tube can be 0.5-1.5 mL / min, such as 0.8-1.5 mL / min or 0.5-1.2 mL / min.

[0053] For example, the liquid phase input flow rate of the liquid inlet tube can be 0.8-1.2 mL / min, and the gas phase input flow rate of the gas inlet tube can be 0.8-1.2 mL / min.

[0054] The present application also provides a microfluidic device, which can be applied to the method for microfluidic oxidation of thiosulfate salt according to any one of the above embodiments. The microfluidic device comprises a supply unit and a reaction collection unit. The supply unit comprises a liquid inlet tube for supplying a thiosulfate salt solution and a gas inlet tube for supplying oxygen. The reaction collection unit comprises a connecting device and a collection tube. The connecting device connects the liquid inlet tube and the gas inlet tube as a confluence point, and the collection tube is connected downstream of the connecting device. In the connecting device, the thiosulfate salt solution and the oxygen are confluenced to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the reaction product is collected by the collection tube.

[0055] In order to facilitate further understanding of the present application by those skilled in the art, examples are provided as follows: Example 1 The gas-liquid phase flow rate is set to 1 mL / min, the liquid phase is supplied with a thiosulfate salt solution with pH = 1, and the concentration of thiosulfate salt in the thiosulfate salt solution is 20 g / L.

[0056] The thiosulfate salt solution and the oxygen are confluenced in the microfluidic chip to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the reaction product is collected by the collection tube. At this time, the size of the oxygen micro-nano bubbles is 1400 nm, wherein the channel depth of the microfluidic chip is 100 um, and the channel width is 500 um.

[0057] In this embodiment, the oxidation rate of thiosulfate is about 100%.

[0058] Example 2 The gas-liquid phase flow rate is set to 1 mL / min, the liquid phase is supplied with a thiosulfate salt solution with pH = 2, and the concentration of thiosulfate salt in the thiosulfate salt solution is 20 g / L.

[0059] The thiosulfate solution and oxygen converge in the microfluidic chip to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the obtained reaction product is collected by a collection tube, at this time the size of the oxygen micro-nano bubbles is 1400nm; wherein the channel depth of the microfluidic chip is 100um, and the channel width is 500um.

[0060] Through Example 2, the oxidation rate of thiosulfate is 92%.

[0061] Example 3 The gas phase flow rate is set to 1mL / min, the liquid phase flow rate is set to 0.5mL / min, and the liquid phase is connected to a thiosulfate solution with pH=1, and the concentration of thiosulfate in the thiosulfate solution is 20g / L.

[0062] The thiosulfate solution and oxygen converge in the microfluidic chip to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the obtained reaction product is collected by a collection tube, at this time the size of the oxygen micro-nano bubbles is 1400nm; wherein the channel depth of the microfluidic chip is 100um, and the channel width is 500um.

[0063] Through Example 3, the oxidation rate of thiosulfate is 84%.

[0064] Example 4 The gas phase flow rate is set to 2mL / min, the liquid phase flow rate is set to 1mL / min, and the liquid phase is connected to a thiosulfate solution with pH=1, and the concentration of thiosulfate in the thiosulfate solution is 20g / L.

[0065] The thiosulfate solution and oxygen converge in the microfluidic chip to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the obtained reaction product is collected by a collection tube, at this time the size of the oxygen micro-nano bubbles is 2000nm; wherein the channel depth of the microfluidic chip is 100um, and the channel width is 500um.

[0066] Through Example 4, the oxidation rate of thiosulfate is 95%.

[0067] Example 5 The gas phase flow rate is set to 1mL / min, the liquid phase flow rate is set to 0.5mL / min, and the liquid phase is connected to a thiosulfate solution with pH=1, and the concentration of thiosulfate in the thiosulfate solution is 20g / L.

[0068] The thiosulfate solution and oxygen converge in the microfluidic chip to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction, and the obtained reaction product is collected by a collection tube, at this time the size of the oxygen micro-nano bubbles is 1700nm; wherein the channel depth of the microfluidic chip is 100um, and the channel width is 500um.

[0069] The thiosulfate oxidation rate was 98.2% by Example 5.

[0070] Example 6 The gas phase flow rate was set to 2 mL / min, and the liquid phase flow rate was set to 2 mL / min. The liquid phase was passed through a thiosulfate solution with a pH of 1, and the concentration of thiosulfate in the thiosulfate solution was 20 g / L.

[0071] The thiosulfate solution and oxygen converged in the microfluidic chip to generate a mixed liquid stream containing oxygen micro-nano bubbles and perform an oxidation reaction. The resulting reaction product was collected by the collection tube. At this time, the size of the oxygen micro-nano bubbles was 800 nm. The channel depth of the microfluidic chip was 100 um, and the channel width was 500 um.

[0072] The thiosulfate oxidation rate in this example was 98%. The XRD pattern of the oxidation product in this example is shown in Figure 3 Compared with the XRD pattern of the conventional large bubble oxidation product in Comparative Example 3, it can be seen that the oxidation product obtained in this example has a significant advantage in purity, showing a higher purity level. Specifically, as shown in Figure 3 The XRD spectra of the sulfur oxide products prepared under different bubble sizes (800 nm micro-bubbles and conventional large bubbles) are completely consistent with the standard spectrum SulfrS-PDF#08-0247, confirming that the main component of all oxidation products is orthorhombic elemental sulfur. The main diffraction peaks are located at 20 angles of 25.9° and 27.8°, corresponding to the 23.10, (222)(311) crystal planes of sulfur single element, respectively. By comparing the XRD spectra of samples with different bubble sizes, it can be found that as the bubble size decreases, the diffraction peak intensity of the sample relatively increases, the peak shape becomes more sharp, and the half peak width decreases, indicating that the smaller the bubble size, the higher the crystallinity of the obtained sulfur particles. In particular, the diffraction peak intensity of the 800 nm bubble sample in the range of 22-30° is significantly higher than that of other samples, indicating that the sulfur particles formed under the micro-bubble system have higher crystallinity and fewer lattice defects.

[0073] Comparative Example 1 Compared with Example 1, the pH of the thiosulfate solution was adjusted to 5 in this example, and other conditions remained unchanged.

[0074] The thiosulfate oxidation rate in this example was 20%.

[0075] Comparative Example 2 Compared with Example 1, the pH of the thiosulfate solution was adjusted to 5 in this example, and other conditions remained unchanged.

[0076] The thiosulfate oxidation rate in this example was almost 0%.

[0077] Comparative Example 3 Compared with Example 1, other conditions are unchanged, only the microfluidic technology is replaced by: oxygen is directly aerated into the thiosulfate solution with pH = 1, and the reaction occurs in the macroscopic system; the amount of oxygen used in the present comparative example is the same as that in Example 1.

[0078] The oxidation rate of thiosulfate in the present comparative example is 60%.

[0079] Analysis Example 1 On the basis of Example 1, the pH of the thiosulfate solution is adjusted in this analysis example to study the oxidation rate of thiosulfate under the condition of pH = 1-10, and the results are shown in Table 1. Figure 1

[0080] Analysis Example 2 On the basis of Example 1, the gas-liquid flow rate is adjusted in this analysis example to explore the oxidation rate of thiosulfate under different bubble sizes, and the results are shown in Table 2. Figure 2

[0081] In the above technical solutions of the present application, the above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made under the technical concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.​​

Claims

1. A method of microfluidic oxidation of thiosulfate salt, characterized by, The method comprises the steps of: Generating oxygen micro-nano bubbles by using a micro-fluid device, the oxygen micro-nano bubbles being used for oxidation reaction with a thiosulfate solution to generate an oxidation product; and controlling the oxidation reaction to be carried out under the condition that the pH is 0.5-3.

2. The method of microfluidic oxidation of thiosulfate salt according to claim 1, characterized in that, The size of the oxygen micro-nano bubbles is 800-1700 nanometers.

3. The method of microfluidic oxidation of thiosulfate salt according to claim 2, characterized in that, The size of the oxygen micro-nano bubbles is 1000-1600 nanometers.

4. The method of microfluidic oxidation of thiosulfate salt according to claim 1, wherein, The micro-fluid device comprises a micro-fluid chip assembly and / or a three-way connection PTFE pipeline assembly.

5. The method of microfluidic oxidation of thiosulfate salt according to claim 4, characterized in that, The micro-fluid device comprises: a feeding unit comprising a liquid inlet pipe for feeding the thiosulfate solution and a gas inlet pipe for feeding oxygen; a reaction collecting unit comprising a connecting device and a collecting pipe; the connecting device is connected to the liquid inlet pipe and the gas inlet pipe as a confluence point, and the collecting pipe is connected downstream of the connecting device; wherein the thiosulfate solution and the oxygen converge at the connecting device to generate a mixed liquid stream containing oxygen micro-nano bubbles and carry out oxidation reaction, and the obtained reaction product is collected by the collecting pipe.

6. The method of microfluidic oxidation of thiosulfate salt according to claim 5, wherein, The connecting device of the three-way connection PTFE pipeline assembly is a PTFE guide pipe with an inner diameter of 1-1.2 mm; and the connecting device of the micro-fluid chip assembly is a micro-fluid chip.

7. The method of microfluidic oxidation of thiosulfate salt according to claim 5, wherein, The liquid phase input flow rate of the liquid inlet pipe is 0.8-2.5 mL / min, and the gas phase input flow rate of the gas inlet pipe is 0.5-2.5 mL / min.

8. The method of microfluidic oxidation of thiosulfate salt according to claim 5, wherein, The liquid phase input flow rate of the liquid inlet pipe is 0.5-2 mL / min, and the gas phase input flow rate of the gas inlet pipe is 1-2 mL / min.

9. The method of microfluidic oxidation of thiosulfate salt according to claim 4, wherein, The internal channel of the micro-fluid chip has a depth of 50-150 um and a width of 400-600 um.

10. A microfluidic device, characterized in that, The method comprises a feeding unit and a reaction collecting unit: a feeding unit comprising a liquid inlet pipe for feeding the thiosulfate solution and a gas inlet pipe for feeding oxygen; a reaction collecting unit comprising a connecting device and a collecting pipe; the connecting device is connected to the liquid inlet pipe and the gas inlet pipe as a confluence point, and the collecting pipe is connected downstream of the connecting device; wherein the thiosulfate solution and the oxygen converge at the connecting device to generate a mixed liquid stream containing oxygen micro-nano bubbles and carry out oxidation reaction, and the obtained reaction product is collected by the collecting pipe.

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