Wastewater treatment method

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a wastewater treatment method which comprises the following steps: feeding wastewater and air into a micro-channel reactor and enabling the wastewater and the air to flow in the micro-channel reactor; irradiating the micro-channel reactor by adopting a light source, and carrying out photocatalytic degradation; wherein the depth of a reaction channel in the micro-channel reactor is 0.1 mm-1 mm, the width of the reaction channel is 2 mm-20 mm, and a photocatalyst film is arranged on at least part of the inner wall of the reaction channel. By adopting the wastewater treatment method provided by the invention, catalyst separation treatment is not needed, the mass transfer efficiency is high, and the photocatalytic degradation efficiency is high.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a method for treating wastewater. Background Technology

[0002] Water bodies are severely polluted due to industrial wastewater discharge, the use of antibiotics, and the use of pharmaceuticals in agricultural products. Physical or chemical methods are generally used to treat organic pollutants in water. Physical methods, mainly including adsorption and flocculation sedimentation, usually cannot fundamentally eliminate pollutants. Chemical methods, such as ozone oxidation, Fenton's reagent oxidation, and photocatalytic oxidation, primarily work by degrading organic pollutants into smaller molecules, thereby completely eliminating them. However, ozone oxidation and Fenton's reagent oxidation require the use of ozone, H₂O₂, and Fe²⁺. 2+ Chemical reagents such as solutions are costly and can easily cause environmental pollution. Therefore, photocatalytic degradation, as a green and low-carbon method for degrading organic pollutants, has been widely studied.

[0003] Traditional photocatalytic degradation methods include powder suspension systems and thin-film systems. In powder suspension systems, nanoparticle catalyst powder is directly added to polluted water. However, the photocatalyst particles dispersed in the water cause severe light scattering, affecting light absorption at the reaction centers. Furthermore, since the catalyst powder remains suspended in the water after degradation, it needs to be separated to prevent secondary pollution. Separating nano-sized photocatalysts from water is very difficult and costly. Thin-film systems, on the other hand, involve fixing the catalyst onto a substrate to form a thin film. While this eliminates the need for catalyst recovery, traditional thin-film reactors suffer from low photocatalytic degradation efficiency due to the limited specific surface area of ​​the catalyst and low three-phase mass transfer efficiency between the gas, liquid, and solid phases. Summary of the Invention

[0004] Based on this, this application provides a wastewater treatment method that does not require catalyst separation, has high mass transfer efficiency, and high photocatalytic degradation efficiency.

[0005] This application provides a wastewater treatment method, which includes the following steps:

[0006] Wastewater and air are fed into and flow within the microchannel reactor;

[0007] Photocatalytic degradation is achieved by irradiating a microchannel reactor with a light source.

[0008] The microchannel reactor has a reaction channel with a depth of 0.1 mm to 1 mm and a width of 2 mm to 20 mm, and at least part of the inner wall of the reaction channel is provided with a photocatalyst film.

[0009] In some embodiments, a pretreatment step is included before the wastewater and air are fed into the microchannel reactor: adjusting the pH of the wastewater to a preset pH value; optionally, the preset pH value is 3 to 7.

[0010] In some implementations, the wastewater flow rate is 5 mL / min to 30 mL / min.

[0011] In some implementations, the air flow rate is 5 mL / min to 250 mL / min.

[0012] In some embodiments, the photocatalyst film includes one or more of the following: titanium dioxide film, zinc oxide film, nitrogen-doped titanium dioxide film, carbon-doped titanium dioxide film, and titanium dioxide-silicon dioxide film.

[0013] In some embodiments, the microchannel reactor includes a substrate, which includes a first substrate and a second substrate that are detachably coupled. Each of the opposing surfaces of the first substrate and the second substrate is provided with an inlet channel, a reaction unit communicating with the inlet channel, and an outlet channel communicating with the reaction unit. The reaction unit includes an arc-shaped channel and a microfluidic channel that are interconnected. A separator is provided in the arc-shaped channel, and the surface of the separator closer to the opposing surface is lower than the opposing surface. The corresponding inlet channel, arc-shaped channel, microfluidic channel and outlet channel on the first substrate and the second substrate are independently coupled to form a reaction channel.

[0014] In some implementations, the surface of the fluid distributor closest to the opposite surface is 0.02 mm to 0.04 mm lower than the opposite surface.

[0015] In some embodiments, the shape of the fluid separator is rhomboid, with a side length of 1 mm to 4 mm and an angle of 90° to 150° along the direction of liquid flow.

[0016] In some implementations, the number of arc-shaped channels and microfluidic channels is independently multiple, the arc-shaped channels and microfluidic channels are arranged alternately and interconnected, and the multiple arc-shaped channels and multiple microfluidic channels are distributed along the same direction or in a meandering manner.

[0017] In some implementations, the widths of the microfluidic channel, the sample inlet channel, and the sample outlet channel are each independently 2 mm to 10 mm.

[0018] In some implementations, the length of the arc-shaped channel is 4mm to 6mm.

[0019] In some implementations, the width of the arc-shaped channel is 5mm to 20mm.

[0020] Compared with the prior art, this application has the following beneficial effects:

[0021] This application achieves photocatalytic degradation of organic pollutant molecules in wastewater by passing wastewater and air through a photocatalyst film loaded on the inner wall of a microchannel reactor with submicron dimensions. The submicron depth of the reaction channel enhances mixing and mass transfer efficiency, while the millimeter width reduces internal resistance and increases liquid flow rate, thus significantly improving photocatalytic degradation efficiency. Furthermore, the photocatalyst film is fixed to the inner wall of the reaction channel and does not disperse into the wastewater solution, eliminating the need for subsequent catalyst separation and reducing costs. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a wastewater treatment method according to one embodiment of this application.

[0024] Figure 2 This is a schematic diagram of a microchannel reactor according to one embodiment of this application.

[0025] Figure 3 This is a schematic diagram of multiple interconnected arc-shaped channels in one embodiment of this application.

[0026] Explanation of reference numerals in the attached figures

[0027] 10. Microchannel reactor;

[0028] 100, First substrate; 200, Second substrate;

[0029] 110, First feed inlet; 120, Second feed inlet; 130, Discharge outlet; 140, Sample inlet channel; 1510, Arc-shaped channel; 1520, Flow divider; 160, Sample outlet channel; 170, Microflow channel; 180, Threaded through hole; 210, First blind hole; 220, Second blind hole; 230, Third blind hole. Detailed Implementation

[0030] A detailed reference is now provided to embodiments of this application, one or more of which are described below. Each embodiment is provided for explanation and not for limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0031] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.

[0032] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0033] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0034] In this article, when referring to units of data ranges, if a unit is only followed by the right endpoint, it means that the units of the left and right endpoints are the same.

[0035] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0036] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0037] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0038] like Figure 1As shown, the first aspect of this application provides a wastewater treatment method, which includes the following steps:

[0039] S1. Wastewater and air are fed into the microchannel reactor and flow within it.

[0040] S2. Photocatalytic degradation is carried out by irradiating the microchannel reactor with a light source.

[0041] The microchannel reactor has a reaction channel with a depth of 0.1 mm to 1 mm and a width of 2 mm to 20 mm, and at least part of the inner wall of the reaction channel is provided with a photocatalyst film.

[0042] It should be noted that, in this application, "width" refers to the dimension perpendicular to the direction of liquid flow within the plane defined by the first direction X and the second direction Y; "length" refers to the dimension along the direction of liquid flow within the plane defined by the first direction X and the second direction Y; "depth" refers to the dimension along a third direction, which is a direction simultaneously perpendicular to the first direction X and the second direction Y; and "height" refers to the dimension along a third direction.

[0043] This application achieves photocatalytic degradation of organic pollutant molecules in wastewater by passing wastewater and air through a photocatalyst film loaded on the inner wall of the reaction channel in a microchannel reactor with submicron dimensions.

[0044] The reaction channel has a submicron depth, which enhances the mixing and mass transfer efficiency within the channel. Its millimeter width reduces internal resistance and increases liquid flow rate, thus significantly improving photocatalytic degradation efficiency. Furthermore, the photocatalyst film is fixed to the inner wall of the reaction channel, preventing dispersion into the wastewater solution and eliminating the need for subsequent catalyst separation, thereby reducing costs.

[0045] In some implementations, a pretreatment step is included before the wastewater and air are fed into the microchannel reactor: the pH of the wastewater is adjusted to a preset pH value.

[0046] In some implementations, the preset pH value is 3 to 7.

[0047] In some embodiments, the flow rate of the wastewater is 5 mL / min to 30 mL / min, including but not limited to 5 mL / min, 10 mL / min, 20 mL / min, and 30 mL / min.

[0048] In some embodiments, the air flow rate is 5 mL / min to 250 mL / min, including but not limited to 5 mL / min, 50 mL / min, 100 mL / min, 200 mL / min, and 250 mL / min.

[0049] This application ensures the degradation efficiency of photocatalysis by controlling the flow rates of wastewater and air within a suitable range, thus guaranteeing sufficient wastewater holding capacity in the microchannel reactor reaction channel and providing enough oxygen reactants for the generation of active superoxide radicals in the photocatalytic reaction.

[0050] It is understood that this application does not specifically limit the type of photocatalyst film. Without departing from the overall inventive concept of this application, any known photocatalyst film can be applied to this application. The following is only an example. In some embodiments, the photocatalyst film includes, but is not limited to, one or more of titanium dioxide film, zinc oxide film, nitrogen-doped titanium dioxide film, carbon-doped titanium dioxide film, and titanium dioxide-silicon dioxide film.

[0051] In some embodiments, a photocatalyst film is prepared on at least a portion of the inner wall of the reaction channel using physical vapor deposition.

[0052] In some embodiments, the thickness of the photocatalyst film is 10 nm to 1000 nm.

[0053] In some embodiments, the photocatalyst film is a titanium dioxide film.

[0054] Titanium dioxide thin films were prepared using a vacuum evaporation coating machine and PVD (physical vapor deposition) technology. Specifically, titanium pentoxide (Ti3O5) was heated in a vacuum environment using an electron gun evaporator, causing its vapor phase to sublimate and deposit onto the inner wall of the reaction channel to form a titanium dioxide thin film. The vacuum level was 1×10⁻⁶. -5 Toor~6×10 -5 The substrate temperature is 60℃~100℃, the ion bombardment working time is 2min~50min, the argon (Ar) flow rate is 5sccm~80sccm, the oxygen flow rate is 10sccm~200sccm, and the oxygen partial pressure (based on the sum of the argon and oxygen flow rates as a percentage, with oxygen as the percentage of the flow rate) is 10%~80%, in order to prevent titanium ions from losing oxygen during the evaporation process and to ensure that it is completely converted into a titanium dioxide thin film.

[0055] In some embodiments, the light source is an ultraviolet light source and / or a visible light source, used to excite the photocatalyst to generate charge carriers. After the photocatalyst is excited to generate charge carriers, it transfers water molecules and oxygen molecules adsorbed on the interface through redox reactions to form active free radical species. The active free radical species cause the organic pollutants in the wastewater to break bonds, degrade into small molecules, and finally mineralize into inorganic products such as carbon dioxide and water.

[0056] In some implementations, the wavelength of the light source is 250nm to 600nm.

[0057] It is understandable that the light source can be placed around the microchannel reactor, on the upper or lower surface of the microchannel reactor, or on the upper or lower surface of the microchannel reactor alone.

[0058] It is understood that, without departing from the overall inventive concept of this application, any wastewater that can be photocatalytically degraded can be treated using the treatment method provided in this application. Hereinafter, for example only, the wastewater includes at least one of methyl orange wastewater, methylene blue wastewater, and amoxicillin wastewater.

[0059] like Figures 2-3 As shown, a second aspect of this application provides a microchannel reactor 10, including a substrate. The substrate includes a first substrate 100 and a second substrate 200 that are detachably coupled. Each of the opposing surfaces of the first substrate 100 and the second substrate 200 is provided with a sample inlet channel 140, a reaction unit communicating with the sample inlet channel 140, and a sample outlet channel 160 communicating with the reaction unit.

[0060] The reaction unit includes an interconnected arc-shaped channel 1510 and a microfluidic channel 170; a fluid separator 1520 is provided in the arc-shaped channel 1510, and the surface of the fluid separator 1520 near the opposite surface is lower than the opposite surface.

[0061] The corresponding sample inlet channel 140, arc-shaped channel 1510, microfluidic channel 170 and sample outlet channel 160 on the first substrate 100 and the second substrate 200 respectively cooperate to form a reaction channel, and at least one of the reaction channels is provided with a photocatalyst film on its inner wall.

[0062] It is understood that the corresponding sample inlet channels 140 on the first substrate 100 and the second substrate 200 cooperate to form a first reaction channel. The corresponding arc-shaped channels 1510 on the first substrate 100 and the second substrate 200 cooperate to form a second reaction channel. The corresponding microfluidic channels 170 on the first substrate 100 and the second substrate 200 cooperate to form a third reaction channel. The corresponding sample outlet channels 160 on the first substrate 100 and the second substrate 200 cooperate to form a fourth reaction channel.

[0063] In some implementations, the maximum depth of the second reaction channel is 0.1 mm to 1 mm.

[0064] The microchannel reactor 10 provided in this application, by setting up an arc-shaped channel 1510 and a separator 1520 structure, allows the fluid flowing through the arc-shaped channel 1510 to be divided into two by the separator 1520 within the arc-shaped channel 1510, and then reunited at the outlet of the arc-shaped channel 1510. This alternating process promotes the convective mixing of the liquid sample, improves the mass transfer effect, increases the degradation efficiency, and has low energy consumption.

[0065] The microchannel reactor 10 used in this application has a small channel size and a large specific surface area, which can accommodate more reactants per unit reactor volume, and thus requires a smaller volume to process the same reactants.

[0066] The microchannel reactor 10 provided in this application eliminates the need for separation of liquid and catalyst, thereby improving production efficiency.

[0067] The microchannel reactor 10 provided in this application is composed of a first substrate 100 and a second substrate 200 that can be detachably fitted, which facilitates disassembly and cleaning and reduces the difficulty of cleaning.

[0068] This application performs a surface reduction process on the fluid distributor 1520, that is, sets the surface of the fluid distributor 1520 closer to the opposite surface to be lower than the opposite surface, while ensuring the liquid distribution effect and the tight bonding between the first substrate 100 and the second substrate 200.

[0069] In some embodiments, a photocatalyst film is provided on the inner wall of the sample inlet channel, the arc-shaped channel, the microfluidic channel, and the sample outlet channel.

[0070] In some embodiments, the surface of the fluid separator 1520 on the side closest to the opposite surface is 0.02 mm to 0.04 mm lower than the opposite surface.

[0071] In some embodiments, the shape of the fluid separator 1520 is circular or square.

[0072] In some embodiments, the shape of the fluid separator 1520 is rhomboid, with a side length of 1mm to 4mm and an angle of 90° to 150° along the direction of liquid flow.

[0073] In some embodiments, the distributor 1520 is centrally located within the arcuate channel 1510, and the width of the distributor 1520 is 1 / 2 to 1 / 4 of the width of the arcuate channel 1510.

[0074] It should be noted that the width of the fluid distributor 1520 in this application refers to the maximum width of the fluid distributor 1520, and the width of the arc-shaped channel 1510 refers to the maximum width of the arc-shaped channel 1510.

[0075] If the size of the distributor 1520 is too small, the distribution effect will be poor and the processing will be difficult; while if the size is too large, the internal resistance will be increased. Therefore, this application sets the width of the distributor 1520 to 1 / 2 to 1 / 4 of the width of the arc channel 1510 in order to reduce the processing difficulty, reduce the internal resistance, and improve the distribution effect.

[0076] In some embodiments, the widths of the microfluidic channel 170, the sample inlet channel 140, and the sample outlet channel 160 are each independently 2mm to 10mm, including but not limited to 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, and 10mm.

[0077] In some embodiments, the depths of the microfluidic channel 170, the sample inlet channel 140, and the sample outlet channel 160 are each independently 0.05 mm to 0.5 mm, including but not limited to 0.05 mm, 0.1 mm, 0.2 mm, 0.4 mm, and 0.5 mm. Further, the depths of the microfluidic channel 170, the sample inlet channel 140, and the sample outlet channel 160 are each independently 0.05 mm to 0.2 mm.

[0078] It should be noted that the widths of the microfluidic channel 170, the sample inlet channel 140, and the sample outlet channel 160 in this application refer to the maximum widths of the microfluidic channel 170, the sample inlet channel 140, and the sample outlet channel 160, respectively. The depths of the microfluidic channel 170, the sample inlet channel 140, and the sample outlet channel 160 refer to the maximum depths of the microfluidic channel 170, the sample inlet channel 140, and the sample outlet channel 160, respectively.

[0079] Since the flow channels of the traditional microchannel reactor 10 are all set to the micrometer scale in all directions, the internal resistance is very large and the liquid flow rate is small. Therefore, this application sets the width of the microchannel 170, the sample inlet channel 140 and the sample outlet channel 160 to the millimeter scale and the depth to the submicrometer scale, which increases the liquid flow rate while ensuring the submicrometer scale effect.

[0080] In some embodiments, the length H of the arc-shaped channel 1510 is 4mm to 6mm, including but not limited to 4mm, 4.5mm, 5mm, 5.5mm, and 6mm.

[0081] It should be noted that the length H of the arc-shaped channel 1510 refers to the length of a single arc-shaped channel 1510. See [link / reference]. Figure 3 .

[0082] In some embodiments, the length and width W of the arc-shaped channel 1510 are 5mm to 20mm, including but not limited to 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 15mm, and 20mm.

[0083] Because a depth of less than 0.05 mm would create significant resistance to liquid flow, while a depth greater than 0.5 mm would reduce mass transfer efficiency, the depth of the arc-shaped channel 1510 is 0.05 mm to 0.5 mm, including but not limited to 0.05 mm, 0.1 mm, 0.2 mm, 0.4 mm, and 0.5 mm. Further, the depth of the arc-shaped channel 1510 is 0.05 mm to 0.2 mm to reduce resistance and improve mass transfer efficiency.

[0084] It should be noted that, in this application, the width W of the arc-shaped channel 1510 refers to the maximum width of the arc-shaped channel 1510. The depth of the arc-shaped channel 1510 refers to the maximum depth of the arc-shaped channel 1510.

[0085] This application increases the flow rate of liquid while ensuring the micron-scale effect by setting the width W and length H of the arc channel 1510 to millimeters and the depth to micrometers.

[0086] In some embodiments, the arc-shaped channel 1510 is a circular arc-shaped channel 1510, with the line connecting the inlet and outlet of the arc-shaped channel 1510 as the axis of symmetry, and the circular arc-shaped channel 1510 has a bilateral symmetrical structure.

[0087] In some embodiments, the number of arc-shaped channels 1510 and microfluidic channels 170 is independently multiple, the arc-shaped channels 1510 and microfluidic channels 170 are arranged alternately and communicate with each other, and the multiple arc-shaped channels 1510 and multiple microfluidic channels 170 are distributed along the same direction or in a meandering manner.

[0088] In some embodiments, the length of the microfluidic channel 170 between two adjacent arcuate channels 1510 distributed along the same direction is 1 / 2 to 1 / 8 of the length of the arcuate channel 1510.

[0089] In some embodiments, the first substrate 100 further includes a first feed port 110 and a second feed port 120, each of which is independently connected to the reaction unit through a sample inlet channel 140 for the inflow of wastewater and air. It is understood that both the first feed port 110 and the second feed port 120 are through-holes disposed on the first substrate 100.

[0090] In some embodiments, the first substrate 100 further includes a discharge port 130, which is located at the end of the sample outlet channel 160 away from the reaction unit for liquid outflow.

[0091] In some embodiments, the second substrate 200 further includes a first blind via 210, a second blind via 220, and a third blind via 230. The first blind via 210 cooperates with the first feed port 110 to form a first sample inlet port, the second blind via 220 cooperates with the second feed port 120 to form a second sample inlet port, and the third blind via 230 cooperates with the discharge port 130 to form a sample outlet port.

[0092] In some embodiments, both the first substrate 100 and the second substrate 200 are glass substrates.

[0093] Glass substrates include, but are not limited to, one or more of borosilicate glass substrates, quartz glass substrates, and high aluminosilicate glass substrates.

[0094] In some embodiments, threaded through holes 180 are independently provided on the side areas of the first injection port, the second injection port, and the outlet port, and are fixed by bolts to the threaded through holes 180 to prevent leakage from the injection port and the outlet port.

[0095] In some embodiments, the first cover plate and the second cover plate are bonded together by adhesive.

[0096] In some embodiments, the first cover plate and the second cover plate are bonded together by heat fusion.

[0097] Because a titanium dioxide thin film was deposited on the first substrate 100 and the second substrate 200 before thermal fusion, the opposing surfaces of the first substrate 100 and the second substrate 200 become rough, which in turn prevents the thermal fusion process from being performed and makes it impossible for the first substrate 100 and the second substrate 200 to fit tightly together.

[0098] Therefore, in some embodiments, a shielding film is provided on the opposing surfaces of the first substrate 100 and the second substrate 200 to shield and protect the opposing surfaces, ensuring a tight fit between the first substrate 100 and the second substrate 200.

[0099] However, since the distributors 1520 exist independently and are not connected to each other, it is difficult to perform shielding treatment. Therefore, during the deposition of the titanium dioxide film, the distributors 1520 will also be coated with titanium dioxide film, causing the upper surface of the distributors 1520 (the side surface near the opposite surface) to protrude a portion relative to the first substrate 100. Therefore, this application performs a surface reduction treatment on the distributors 1520, that is, the side surface of the distributors 1520 near the opposite surface is 0.02mm~0.04mm lower than the opposite surface, so as to ensure that the first substrate 100 and the second substrate 200 are tightly bonded together, while ensuring the function of liquid diversion.

[0100] In this application, the preparation method of the microchannel reactor 10 is not particularly limited. Without departing from the overall inventive concept of this application, any known method that can be used to prepare the microchannel reactor 10 can be applied to this application.

[0101] It is understandable that, in the process of preparing the microchannel reactor 10 provided in this application, all processing surfaces need to be chamfered in order to prevent the glass substrate from cracking during processing.

[0102] A third aspect of this application provides a photocatalytic reaction apparatus, including a microchannel reactor 10 as provided in the second aspect of this application, and a light source for irradiating the microchannel reactor 10.

[0103] In some embodiments, a peristaltic pump is provided at the first feed inlet 110 to provide driving force for the wastewater to be pumped into the sample inlet channel 140.

[0104] An air pump is provided at the second inlet 120. The air pump is connected to the second inlet 120 through a rubber tube and continuously pumps air into the sample inlet channel 140 to provide oxygen to the microchannel reactor 10. Oxygen, as one of the reactants in the photocatalytic reaction, acts as an electron acceptor and forms free radical active species.

[0105] Understandably, wastewater and air flow from the inlet port to the outlet port under the pressure of the pump. During the flow, the liquid and gas mix to form Taylor flow, bubble flow and annular flow. The gas-liquid mixture comes into contact with the photocatalyst on the inner wall of the reaction channel during the flow to form liquid-solid interface, gas-solid interface and gas-liquid-solid three-phase interface.

[0106] In some embodiments, the discharge port 130 is connected to a collection bottle via a connecting pipe for collecting treated wastewater into the collection bottle.

[0107] Understandably, if multiple cycles are required, the first inlet 110 can be connected to a collection bottle via a connecting pipe, and the wastewater in the collection bottle can be pumped into the microchannel reactor 10 by a peristaltic pump for the next treatment, thus repeating the reaction cycle. Alternatively, multiple microchannel reactors 10 can be connected in series until the organic pollutants in the wastewater are completely degraded.

[0108] Furthermore, this application provides the following specific embodiments and comparative examples to further illustrate the specific implementation of this application and its advantages.

[0109] Example 1

[0110] The microchannel reactor 10 has dimensions of 170mm × 145mm × 4mm (length, width, and height) and includes a substrate. The substrate includes a first substrate 100 and a second substrate 200 that can be detachably fitted together. Both the first substrate 100 and the second substrate 200 are high borosilicate glass substrates. Each of the opposing surfaces of the first substrate 100 and the second substrate 200 is provided with an inlet channel 140, a reaction unit communicating with the inlet channel 140, and an outlet channel 160 communicating with the reaction unit. The reaction unit includes an interconnected arc-shaped channel 1510 and a microfluidic channel 170. A separator 1520 is provided inside the arc-shaped channel 1510. The surface of the separator 1520 on the side closest to the opposing surface is 0.03mm lower than the opposing surface. The corresponding inlet channel 140, arc-shaped channel 1510, microfluidic channel 170, and outlet channel 160 on the first substrate 100 and the second substrate 200 respectively cooperate to form a reaction channel. The inner wall of each reaction channel is provided with a titanium dioxide film. The reaction channel has a depth of 0.4 mm. The sample inlet channel 140, microfluidic channel 170, and sample outlet channel 160 are all 6 mm wide. The arc-shaped channel 1510 is a circular arc-shaped channel with a width of 12.5 mm and a length of 5 mm. The distance between two adjacent arc-shaped channels 1510 in the same column is 1.5 mm. The fluid separator 1520 is a rhombus-shaped island with a side length of 2.5 mm and a rhombus angle of 45° along the first direction. The titanium dioxide film has a thickness of 500 nm.

[0111] The first substrate 100 is provided with a first inlet 110 and a second inlet 120, each of which is independently connected to the reaction unit through a sample inlet channel 140. The first substrate 100 is also provided with an outlet 130, which is connected to a sample outlet channel 160. The second substrate 200 is provided with a first blind hole 210, a second blind hole 220, and a third blind hole 230, which are respectively provided corresponding to the first inlet 110, the second inlet 120, and the outlet 130. After the first substrate 100 and the second substrate 200 are thermally fused together, the first blind hole 210 and the first inlet 110 cooperate to form a liquid inlet port, the second blind hole 220 and the second inlet 120 cooperate to form an air inlet port, and the third blind hole 230 and the outlet 130 cooperate to form a sample outlet port.

[0112] The microchannel reactor 10 is equipped with ultraviolet lamps fixed at parallel positions above and below, with a wavelength of 365 nm and an irradiation intensity of 5 mW / cm². 2 .

[0113] A 10 mg / L methyl orange wastewater solution (pH 3.5) is pumped into the sample inlet channel 140 through the first inlet 110 at a flow rate of 30 mL / min. Air is pumped into the sample inlet channel 140 through the second inlet 120 at a flow rate of 120 mL / min. The microchannel reactor 10 is then irradiated with ultraviolet light, causing the methyl orange wastewater solution to undergo photocatalytic degradation within the microchannel reactor 10. Finally, the solution flows out of the microchannel reactor 10 through the sample outlet channel 160.

[0114] The solution flowing out of outlet 130 is repeatedly pumped into microchannel reactor 10 to achieve the cyclical photocatalytic degradation.

[0115] Example 2

[0116] The processing in this embodiment is basically the same as that in embodiment 1, except that the depth of the reaction channel in embodiment 2 is 0.2 mm.

[0117] Example 3

[0118] The treatment in this embodiment is basically the same as that in embodiment 2, except that the wastewater in embodiment 3 is a methylene blue wastewater solution (pH 5.0).

[0119] Example 4

[0120] The treatment in this embodiment is basically the same as that in embodiment 2, except that the wastewater in embodiment 4 is an amoxicillin wastewater solution (pH 3.5).

[0121] Example 5

[0122] The processing method of this embodiment is basically the same as that of embodiment 1, except that the depth of the reaction channel in embodiment 5 is 0.1 mm.

[0123] Example 6

[0124] The processing in this embodiment is basically the same as that in embodiment 1, except that the depth of the reaction channel in embodiment 6 is 1 mm.

[0125] Comparative Example 1

[0126] The reactants were the same as in Example 2, using a 10 mg / L aqueous solution of methyl orange waste (pH 3.5).

[0127] A titanium dioxide film of the same area as in Example 2 was deposited on a flat glass plate. The flat glass plate was placed in a beaker, and the same amount of methyl orange wastewater solution was injected into the beaker. Air was pumped into the methyl orange wastewater solution using a conduit. Ultraviolet lamps with a wavelength of 365 nm and an irradiance of 10 mW / cm² were fixed at parallel positions above and below the beaker. 2 When a beaker is irradiated with ultraviolet light, the methyl orange wastewater solution undergoes photocatalytic degradation within the beaker.

[0128] Comparative Example 2

[0129] The treatment of this comparative example is basically the same as that of Example 1, except that the depth of the reaction channel in Comparative Example 2 is 0.08 mm.

[0130] Comparative Example 3

[0131] The treatment of this comparative example is basically the same as that of Example 1, except that the depth of the reaction channel in Comparative Example 3 is 1.2 mm.

[0132] Test case

[0133] (1) The photocatalytic degradation rate of the wastewater after photocatalytic degradation in Examples 1-3, Examples 5-6 and Comparative Examples 1-3 was tested.

[0134] Take 5 ml of wastewater sample into a cuvette, insert the cuvette into a spectrophotometer, and measure the absorbance at the wavelength of maximum absorption. Measure the absorbance value A of the solution at the wavelength of maximum absorption. t The photocatalytic degradation rate η at time t satisfies the following formula:

[0135] η=(A0-A t ) / A0×100%.

[0136] Where A0 is the absorbance of the initial wastewater solution, A t The absorbance is denoted as t. The time required for complete degradation of organic pollutants in the wastewater was determined, and the results are shown in Table 1 below.

[0137] (2) The concentration of the wastewater solution in Example 4 was measured using liquid chromatography, and the time required for complete degradation of organic pollutants in the wastewater was calculated directly based on the relative area of ​​the peaks in the liquid chromatography. The results are shown in Table 1 below.

[0138] Table 1

[0139]

[0140] According to the data comparison in Table 1, compared with Comparative Example 1, the microchannel reactor in this application significantly improves the photocatalytic degradation efficiency. In particular, the photocatalytic degradation efficiency of Example 2 is more than 10 times higher than that of Comparative Example 1.

[0141] Based on the comparison of Examples 1, 2, and 6 and Comparative Examples 2-3, it can be seen that when the width of the reaction channel is fixed, as the depth of the reaction channel gradually increases within a certain range, the photocatalytic degradation time shows a trend of first decreasing and then increasing, that is, the photocatalytic degradation efficiency first increases and then decreases.

[0142] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0143] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for treating wastewater, characterized in that, The processing method includes the following steps: Wastewater and air are fed into and flow within a microchannel reactor; The microchannel reactor is irradiated with a light source to carry out photocatalytic degradation; The microchannel reactor has a reaction channel with a depth of 0.1 mm to 1 mm and a width of 2 mm to 20 mm, and at least a portion of the inner wall of the reaction channel is provided with a photocatalyst film.

2. The wastewater treatment method according to claim 1, characterized in that, A pretreatment step is also included before the wastewater and air are fed into the microchannel reactor: Adjust the pH value of the wastewater to a preset pH value; Optionally, the preset pH value is 3 to 7.

3. The wastewater treatment method according to claim 1, characterized in that, The flow rate of the wastewater is 5 mL / min to 30 mL / min, and / or The air flow rate is 5 mL / min to 250 mL / min.

4. The wastewater treatment method according to claim 1, characterized in that, The photocatalyst film includes one or more of the following: titanium dioxide film, zinc oxide film, nitrogen-doped titanium dioxide film, carbon-doped titanium dioxide film, and titanium dioxide-silicon dioxide film.

5. The wastewater treatment method according to any one of claims 1-4, characterized in that, The microchannel reactor includes a substrate, which includes a first substrate and a second substrate that can be detachably fitted together. Each of the first substrate and the second substrate has an inlet channel, a reaction unit communicating with the inlet channel, and an outlet channel communicating with the reaction unit on its opposite surfaces. The reaction unit includes interconnected arc-shaped channels and microfluidic channels; a fluid separator is provided in the arc-shaped channel, and the surface of the fluid separator on the side closest to the opposite surface is lower than the opposite surface; The corresponding sample inlet channel, arc-shaped channel, microfluidic channel, and sample outlet channel on the first substrate and the second substrate are independently combined to form the reaction channel.

6. The wastewater treatment method according to claim 5, characterized in that, The surface of the fluid separator closest to the opposite surface is 0.02 mm to 0.04 mm lower than the opposite surface.

7. The wastewater treatment method according to claim 5, characterized in that, The shape of the fluid separator is rhomboid, with a side length of 1mm to 4mm and an angle of 90° to 150° along the direction of liquid flow.

8. The wastewater treatment method according to claim 5, characterized in that, The number of arc-shaped channels and microfluidic channels is independently multiple. The arc-shaped channels and microfluidic channels are arranged alternately and are interconnected. The multiple arc-shaped channels and multiple microfluidic channels are distributed along the same direction or in a meandering manner.

9. The wastewater treatment method according to claim 5, characterized in that, The widths of the microfluidic channel, the sample inlet channel, and the sample outlet channel are each independently 2mm to 10mm.

10. The wastewater treatment method according to claim 5, characterized in that, The arc-shaped channel satisfies at least one of the following characteristics: (1) The length is 4mm~6mm; (2) Width is 5mm~20mm.

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