Method and system for position-selective loading of a catalyst induced by fluid flow

Abstract

The present invention relates to a method and system for position-selective loading of a catalyst induced by fluid flow, which is provided with a flow channel and a catalyst carrier having a forest-like micro-wire array structure located in the flow channel. A first solution containing a catalyst R for inducing the production of active reducing species and a second solution containing a catalyst O for inducing the production of active oxidizing species are respectively introduced into the flow channel at a specific flow rate and in opposite directions. By means of the fluid flow inertia and the steric effect of the catalyst carrier, the catalyst R and the catalyst O are respectively loaded on two opposite specific surfaces of each micro-wire of the catalyst carrier, constructing a catalyst array with spatially separated and "R-O...R-O" alternating distribution along the flow channel direction, so as to induce the spatial and temporal separation of active hydrogen (·H) and hydroxyl radicals (·OH) and alternately generate them in sequence along the flow direction, and finally realize the dynamic cascade synergistic dehalogenation mineralization of polyhalogenated organic pollutants and the synergistic efficiency enhancement treatment of wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a method for position-selective loading of a catalyst induced by fluid flow, which can selectively construct the loading position of the catalyst, achieve spatial separation of two catalysts with different properties on the same catalyst carrier, and further enable the use of two catalysts with different properties on the catalyst carrier and induce the spatial-temporal separation of ·H and ·OH and their alternating generation in sequence along the flow direction. The present invention also relates to a system that can implement the method for position-selective loading of the catalyst based on fluid flow.

[0002] In addition, the present invention also relates to the use of the method and system of the present invention in removing polyhalogenated organic pollutants in water treatment. Background Art

[0003] Polyhalogenated Organic Pollutants (PHOPs) are organic pollutants in which most hydrogen atoms in the molecule are replaced by halogen atoms. Their use in fields such as pesticides, wood preservatives, and herbicides over the past few decades has caused serious pollution of the environment such as water bodies and soil. As a class of priority control pollutants with characteristics such as high toxicity, environmental persistence, and bioaccumulation, PHOPs have currently been restricted / banned from production and use, but their environmental pollution still persists and they are frequently detected in water bodies, soil environments, or even the human body, which has attracted widespread attention worldwide. Due to the low environmental content of PHOPs and the C–X (X represents a halogen atom) structure with high ionization energy, the removal effect of traditional biological and chemical sewage treatment units on them is very limited. In addition, these traditional treatment processes may accumulate small molecule intermediate products, whose toxicity is even higher than that of the parent pollutants. It is worth noting that the high toxicity of PHOPs is highly correlated with the presence of C–X. Therefore, it is crucial to develop advanced and efficient PHOPs treatment technologies to achieve complete dehalogenation and thorough mineralization, which can provide strong support for ensuring the safety of residential water use and promoting the construction of a healthy China.

[0004] Advanced Oxidation Processes (AOPs) combine an oxidant with an activation strategy and use highly reactive oxidation species (such as ·OH, 1 O2) generated during the activation process to achieve the degradation of organic pollutants. Among them, ·OH (E 0= 2.7 V) is considered to be one of the most oxidizing species. It can not only achieve dehalogenation of PHOPs through the hydroxylation pathway, but also non-selectively mineralize the PHOPs parent and its dehalogenation products (such as small molecule organic acids). Therefore, the development of ·OH-based AOPs technology is considered a promising PHOPs degradation technology and has been confirmed in many cases. Nevertheless, the ·OH-driven PHOPs degradation reaction is not only thermodynamically unfavorable but also kinetically slow. This is attributed to the fact that the halogen atom is an electron-withdrawing group, which reduces the highest occupied molecular orbital energy of PHOPs, thus inhibiting the electrophilic attack reaction of ·OH on C–X and making it difficult for PHOPs to undergo hydroxylation dehalogenation. Moreover, the more halogen atoms in PHOPs, the more significant the hindrance to the above electrophilic attack reaction. For this reason, many scholars have proposed strengthening strategies such as ·OH spatial confinement and energy input to improve the hydroxylation dehalogenation and mineralization performance of PHOPs, but none of them can fundamentally avoid the originally unfavorable AOPs reaction. In contrast, active hydrogen (·H, E 0 = -2.3 V) is a strong reducing species. It can easily achieve hydrodehalogenation of PHOPs through the nucleophilic attack reaction on C–X, but the highly toxic dehalogenation products generated cannot be completely removed through the ·H-driven hydrogenation reaction. It should be noted that as the number of halogen atom substitutions decreases, the (partial) dehalogenation products of PHOPs become more resistant to the ·H-driven hydrodehalogenation reaction but easier to the ·OH-driven hydroxylation dehalogenation reaction. It can be seen from this that during the degradation process, with the change in the number of halogen atom substitutions, the PHOPs parent pollutant and its dehalogenation products often exhibit different or even opposite redox characteristics, resulting in the inability of a single (·OH) oxidation method or (·H) reduction method to take into account the efficient dehalogenation and mineralization of both the parent pollutant and the dehalogenation products. Therefore, to achieve the efficient dehalogenation and mineralization of PHOPs, it is urgent to develop new degradation technologies that can meet the requirements of efficient dehalogenation and mineralization of the PHOPs parent and its dehalogenation products.

[0005] In view of the characteristic that "polyhalogenated organic pollutants are easier to reduce, while oligohalogenated organic pollutants are easier to oxidize", most scholars adopt a two-step reduction-oxidation system, that is, first use a reduction method to dehalogenate the PHOPs parent, and then use an oxidation system to oxidatively decompose the dehalogenated products. This combined degradation method has the advantages of fast degradation rate, complete dehalogenation and thorough mineralization. However, this two-step reduction-oxidation combined method still faces major challenges. For example, due to the dynamic changes in the redox properties of the PHOPs parent and its dehalogenated products, it is impossible to ensure that highly reducing and highly oxidizing species attack the PHOPs parent and its dehalogenated products in the most (better) matching reaction path, resulting in the overall dehalogenation mineralization reaction is still hindered. In comparison, the one-step reduction-oxidation combined method is also favored because of its simple operation, that is, by constructing a catalyst on a single substrate material, using the simultaneously generated highly reducing and oxidizing species to synergistically degrade the PHOPs parent and its dehalogenated products. However, the key technical bottleneck of this one-step reduction-oxidation combined method is that it is not only unable to avoid the mutual quenching of highly reducing and oxidizing active species due to spatial proximity, but also unable to ensure that the two can attack the PHOPs matrix and its dehalogenated products in order and efficiently, resulting in the overall dehalogenation mineralization efficiency of PHOPs being limited. Based on the above analysis, according to the characteristics of the molecular structure of PHOPs, a catalyst with spatial separation and ordered structure is constructed to induce the spatiotemporal controllable generation of highly reducing and oxidizing species, and a cascade catalytic degradation system matching the PHOPs reduction / oxidation dehalogenation and oxidation mineralization with the most (better) optimal reaction energy barrier can provide a unique solution for the efficient dehalogenation mineralization of PHOPs. However, up to now, on micro / nanoscale substrate materials, the construction of a spatially separated and ordered distribution structure of two or more catalysts is highly dependent on substrates with specific structures / properties and advanced loading technologies (such as 3D printing technology), but this does not meet the current requirements for the construction of water treatment units that emphasize simplicity, low price and high efficiency. Therefore, it is urgent to develop new water treatment unit construction technologies to enable active species to take into account the efficient dehalogenation and mineralization of PHOPs matrix and its dehalogenation products, but it still faces huge challenges. Summary of the invention

[0006] In view of this, the present invention provides a method and system for position-selective loading of catalysts induced by fluid flow, wherein a catalyst R for inducing the generation of active reducing species and a catalyst O for inducing the generation of active oxidizing species are respectively loaded on two opposite specific surfaces of each micrometer line of the catalyst carrier by means of the inertia of fluid flow and the steric effect of the catalyst carrier, and a catalyst array with spatial separation and extending along the flow channel in the form of "RO...RO" alternating distribution is constructed to induce the temporal and spatial separation of ·H and ·OH and their alternating generation in sequence along the flow direction, ultimately realizing the dynamic cascade synergistic dehalogenation mineralization of polyhalogenated organic pollutants and synergistic treatment of wastewater.

[0007] The first aspect of the present invention discloses a method for position-selective loading of a catalyst induced by fluid flow, comprising the following steps:

[0008] S1, setting a flow channel and constructing a catalyst carrier with a forest-like micro-wire array structure in the flow channel, having gaps between the micro-wires of the catalyst carrier;

[0009] S2, introducing a first solution containing a catalyst R for inducing the production of active reducing species into the flow channel at a specific flow rate, and making the first solution collide with and contact the first surface of the catalyst carrier by means of fluid flow inertia and the steric effect of the catalyst carrier, so that the catalyst R contained therein adheres to the first surface of the catalyst carrier in the form of nano-sized metal single particles to construct a catalytic reduction zone; wherein the first surface is the surface of the catalyst carrier facing the inflow direction of the first solution;

[0010] S3, after step S2, introducing a second solution containing a catalyst O for inducing the production of active oxidizing species into the flow channel at a corresponding specific flow rate in a direction opposite to the flow direction of the first solution, and making the second solution collide with and contact the second surface of the catalyst carrier by means of fluid flow inertia and the steric effect of the catalyst carrier, so that the catalyst O contained therein adheres to the second surface of the catalyst carrier in the form of nano-sized metal alloy particles to construct a catalytic oxidation zone; wherein the second surface is the other surface opposite to the first surface of the catalyst carrier.

[0011] Wherein, in the present invention, each micro-wire in the forest-like micro-wire array structure can be regarded as an individual catalyst carrier, that is, according to the method disclosed in the present invention, the catalyst R for inducing the production of active reducing species is selectively loaded on the first surface of the micro-wire, and the catalyst O for inducing the production of active oxidizing species is selectively loaded on the second surface of the micro-wire, and thus a catalytic reduction zone and a catalytic oxidation zone can be respectively constructed on two opposite surfaces of the micro-wire.

[0012] According to the method disclosed in the first aspect of the present invention, wherein the catalyst R is a metal catalyst selected from one or more of the following: Pt, Pd, Ni, such that the catalyst R adheres to the first surface in the form of nano-sized metal single particles.

[0013] According to the method disclosed in the first aspect of the present invention, wherein the catalyst O is a metal catalyst which is Pd-Au formed by mixing in proportion, such that the catalyst O adheres to the second surface in the form of nano-sized metal alloy particles.

[0014] According to the method disclosed in the first aspect of the present invention, the specific flow rate of the first solution and the corresponding specific flow rate of the second solution are both flow rates of 6 - 20 cm / s. In a particularly preferred embodiment, the specific flow rate of the first solution is set to 6.8 cm / s. Similarly, in a particularly preferred embodiment, the corresponding specific flow rate of the second solution is set to 6.8 cm / s.

[0015] According to the method disclosed in the first aspect of the present invention, in step S1, a fluid tube is provided, and the lumen of the fluid tube forms the flow channel; micron Fe3O4 particles are injected into the lumen, and a parallel magnetic field perpendicular to the flow channel is used to drive the micron Fe3O4 particles to spontaneously form a magnetically constrained micron wire array in the lumen as a catalyst carrier, wherein the magnetically constrained micron wire array is perpendicular to the lumen and extends along the flow channel direction.

[0016] The second aspect of the present invention discloses a system for implementing the method disclosed in the first aspect of the present invention, which includes a fluid tube, a catalyst carrier, and a pumping device. Among them, the lumen of the fluid tube forms the flow channel, the catalyst carrier is configured as a forest-like micron wire array in the flow channel, and the pumping device is configured to be able to introduce a first solution containing a catalyst R for inducing the generation of active reducing species into the flow channel at a specific flow rate, and make the first solution collide and contact with the first surface of the catalyst carrier by means of fluid flow inertia and the steric effect of the catalyst carrier, so that the catalyst contained therein adheres to the first surface of the catalyst carrier in the form of nano metal single particles to construct a catalytic reduction zone; and, after the first solution is introduced, the pumping device can introduce a second solution containing a catalyst O for inducing the generation of active oxidizing species into the flow channel in the opposite direction at a corresponding specific flow rate, and make the second solution collide and contact with the second surface of the catalyst carrier by means of fluid flow inertia and the steric effect of the catalyst carrier, so that the catalyst O contained therein adheres to the second surface of the catalyst carrier in the form of nano metal alloy particles to construct a catalytic oxidation zone; wherein the first surface is the surface of the catalyst carrier facing the inflow direction of the first catalyst solution, and the second surface is the other surface of the catalyst carrier opposite to the first surface.

[0017] According to the system disclosed in the second aspect of the present invention, it further includes a magnetic constraint device, which includes permanent magnets respectively arranged above and below the fluid tube to provide a parallel magnetic field perpendicular to the fluid tube so that the micron Fe3O4 particles injected into the flow channel spontaneously form a micron wire array and are magnetically constrained in the lumen as the catalyst carrier.

[0018] According to the system disclosed in the second aspect of the present invention, the catalyst carrier is a micron wire array perpendicular to the flow channel formed by micron Fe3O4 particles under a parallel magnetic field, and the micron wire array extends along the flow channel direction.

[0019] The third aspect of the present invention discloses a use, specifically, the use of the method disclosed in the first aspect of the present invention and / or the system disclosed in the second aspect of the present invention for removing polyhalogenated organic pollutants in water treatment.

[0020] The fourth aspect of the present invention discloses a water catalytic treatment system, which includes the system disclosed in the second aspect of the present invention.

[0021] Beneficial effects: In the method and system of the present invention based on fluid flow-induced catalyst position-selective loading, a flow channel and a catalyst carrier located in the flow channel are provided. The first solution containing the catalyst R for inducing the generation of active reducing species and the second solution containing the catalyst O for inducing the generation of active oxidizing species can be introduced into the flow channel in opposite directions at specific flow rates respectively. Under the fluid flow inertia at a specific flow rate and the steric hindrance effect of the catalyst carrier, the catalyst R for inducing the generation of active reducing species and the catalyst O for inducing the generation of active oxidizing species are respectively attached to different surfaces of each micron wire serving as the catalyst carrier, realizing the selective construction of the catalyst loading position, and achieving the spatial separation of two different types of catalysts on the same carrier, that is, constructing a catalyst array with spatial separation and extending along the flow channel direction in the form of "R-O…R-O" alternating distribution, so as to induce the spatial and temporal separation of ·H and ·OH and generate them alternately in sequence along the flow direction, and then be able to carry out reduction reactions and oxidation reactions alternately in sequence, ultimately realizing the dynamic cascade synergistic dehalogenation mineralization of polyhalogenated organic pollutants and the synergistic efficiency enhancement treatment of wastewater.

[0022] The technical solution of the present invention will be disclosed in detail below in combination with the embodiments shown in the drawings and the reference numerals. Description of the Drawings

[0023] Figure 1 Shows the step flow chart of the method in the present invention.

[0024] Figure 2 In (a) and Figure 2 In (b) shows the morphology and average size of the micron Fe3O4 particles used in the present invention.

[0025] Figure 3 In (a)-(d) shows the morphology, distribution, average size of the formed micron wires and average spacing of the magnetic confinement micron wire array composed of micron Fe3O4 particles as the catalyst carrier in the fluid tube.

[0026] Figure 4 Shows the schematic diagram of the system device for realizing the catalyst position-selective loading of the disclosed method in the present invention.

[0027] Figure 5 In (a) and Figure 5(b) shows schematic diagrams of the position-selective loading of Pd and Pd-Au as two groups of catalysts respectively.

[0028] Figure 6 The device schematic diagram of the water catalytic treatment system of the present invention is shown.

[0029] Figure 7 (a)-(e) show the flow field distribution when a solution containing model catalyst particles flows through the micro-wires at different loading flow rates and the simulation diagrams of the adsorption distribution of the micro-wires to the model catalyst particles.

[0030] Figures 8(a) and 8(b) show the Pd and Au morphologies and element distribution diagrams on the first surface and the second surface of the titanium wire as a catalyst carrier at a high loading flow rate.

[0031] Figures 9(a) and 9(b) show the Pd and Au morphologies and element distribution diagrams on the first surface and the second surface of the titanium wire as a catalyst carrier at a low loading flow rate.

[0032] Figure 10 The Pd morphology and element distribution diagram on the surface of typical micron Fe3O4 particles of the composition position-selective Pd@Fe3O4 micro-wire array prepared by the method based on the present invention are shown.

[0033] Figure 11 The Pd-Au morphology and element distribution diagram on the surface of typical micron Fe3O4 particles of the composition position-selective Pd-Au@Fe3O4 micro-wire array prepared by the method based on the present invention are shown.

[0034] Figures 12(a) and 12(b) respectively show the Pd and Pd-Au morphologies and element distribution diagrams on the surface of typical micron Fe3O4 particles of the composition position-selective Pd&Pd-Au@Fe3O4 micro-wire array prepared by the method based on the present invention.

[0035] Figure 13 The Pd and Pd-Au morphologies and element distribution diagrams on the surface of typical micron Fe3O4 particles of the position-nonselective Pd&Pd-Au@Fe3O4 micro-wire array prepared at a low loading flow rate are shown.

[0036] Figure 14 The Pd and Pd-Au morphologies and element distribution diagrams on the surface of typical micron Fe3O4 particles of the composition uniformly distributed Pd&Pd-Au@Fe3O4 micro-wire array prepared by the traditional batch adsorption method are shown.

[0037] Figures 15(a)-(c) show the comparison of the 2,4-DCP degradation, dechlorination and mineralization performances of the catalytic system formed by the method based on the present invention and other types of systems in the water treatment system.

[0038] Figure 16 Shows the generation of ·H and ·OH in the catalytic system formed by the method of the present invention and other catalytic systems under different atmosphere conditions. Detailed implementation manners

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other.

[0041] Figure 1 Shows the step flow chart of the method in the present invention. Combining Figure 1 As shown, a method for position-selective loading of a catalyst based on fluid flow induction is disclosed in the first aspect of the present invention, including the following steps:

[0042] S1, set a flow channel and construct a catalyst carrier with a forest-like micro-wire array structure in the flow channel, and there are gaps between the micro-wires of the catalyst carrier;

[0043] S2, introduce a first solution containing a catalyst R for inducing the generation of active reducing species into the flow channel at a specific flow rate. By means of the inertia of fluid flow and the steric effect of the catalyst carrier, the first solution collides with and contacts the first surface of the catalyst carrier, so that the catalyst R contained therein adheres to the first surface of the catalyst carrier in the form of nano metal single particles to construct a catalytic reduction zone; wherein the first surface is the surface of the catalyst carrier facing the inflow direction of the first solution;

[0044] S3, after step S2, introduce a second solution containing a catalyst O for inducing the generation of active oxidizing species into the flow channel in the direction opposite to the flow direction of the first solution at a corresponding specific flow rate. By means of the inertia of fluid flow and the steric effect of the catalyst carrier, the second solution collides with and contacts the second surface of the catalyst carrier, so that the catalyst O contained therein adheres to the second surface of the catalyst carrier in the form of nano metal alloy particles to construct a catalytic oxidation zone; wherein the second surface is the other surface opposite to the first surface of the catalyst carrier.

[0045] Based on the method of the present invention, catalysts with different properties can be selectively loaded on different surfaces of the catalyst support, thereby achieving spatial separation of the catalyst for inducing the generation of active reducing species and the catalyst for inducing the generation of active oxidizing species on the same catalyst support, enabling two catalysts with different properties (the catalyst R for inducing the generation of active reducing species and the catalyst O for inducing the generation of active oxidizing species, respectively) to be simultaneously loaded on each micron line serving as the catalyst support, thus constructing a catalyst array with spatial separation and extending along the flow channel direction in the form of an alternating distribution of "R - O... R - O", for inducing the spatial and temporal separation of ·H and ·OH and alternately generating them in sequence along the flow direction, and further enabling the reduction reaction and the oxidation reaction to be alternately carried out in sequence, ultimately achieving the dynamic cascade synergistic dehalogenation mineralization of polyhalogenated organic pollutants and the synergistic efficiency improvement treatment of wastewater.

[0046] In an embodiment of the method, the catalyst R is a metal catalyst, which is selected from one or more of the following: Pt, Pd, Ni, such that the catalyst R is attached to the first surface of the catalyst support in the form of nano - metal elemental particles.

[0047] In an embodiment of the method, wherein the catalyst O is a metal catalyst, which is Pd - Au formed by mixing in proportion, such that the catalyst O is attached to the second surface of the catalyst support in the form of nano - metal alloy particles.

[0048] In an embodiment of the method, in a preferred embodiment, the specific flow rate of the first solution is the same as the corresponding specific flow rate of the second solution. Specifically, the specific flow rate of the first solution can be set to 6 - 20 cm / s, and in a particularly preferred embodiment, the specific flow rate of the first solution is set to 6.8 cm / s. Similarly, the corresponding specific flow rate of the second solution can also be set to 6 - 20 cm / s, and in a particularly preferred embodiment, the corresponding specific flow rate of the second solution is set to 6.8 cm / s. Of course, those skilled in the art can understand that the specific flow rate of the first solution and the corresponding specific flow rate of the second solution can also be set differently.

[0049] In an embodiment of the method, the first solution containing the catalyst R for inducing the generation of active reducing species is formed by adding a precursor of the catalyst R for inducing the generation of active reducing species to deionized water; and / or, the second solution containing the catalyst O for inducing the generation of active oxidizing species is formed by adding a precursor of the catalyst O for inducing the generation of active oxidizing species to deionized water. In a preferred embodiment, the catalyst R for inducing the generation of active reducing species is set to Pd, which exists in the first solution in the form of Pd 2+ ; while the catalyst O for inducing the generation of active oxidizing species is set to Pd - Au mixed in proportion, where Pd exists in the form of Pd 2+exists in the second solution in the form of, while Au exists in the second solution in the form of Au 3+ exists in the second solution. Pd in the first solution 2+ and Pd in the second solution 2+ and Au 3+ are first captured onto the surface of negatively charged Fe3O4 micro-wires by electrostatic adsorption and reduced to nano-metal particles by Fe3O4 under acidic conditions. Of course, those skilled in the art should also be able to understand that in the present invention, catalyst R and catalyst O can also be catalyst single particles. For example, catalyst R can be Pd single. In addition, regarding the attachment of the catalyst single or catalyst precursor to the surface of the catalyst support, it can be achieved by electrostatic adsorption or by other acting forces, as long as it can achieve the attachment of the induced active reducing species and the induced active oxidizing species to the corresponding specific surfaces with different catalysts respectively.

[0050] In an embodiment of the method, in step S1, a fluid tube is provided, and the lumen of the fluid tube forms the flow channel; micron Fe3O4 particles are injected into the lumen, and the micron Fe3O4 particles are driven by a parallel magnetic field perpendicular to the flow channel to spontaneously form a magnetically confined micron-wire array in the lumen as the catalyst support, wherein the magnetically confined micron-wire array is perpendicular to the lumen and extends along the flow channel direction.

[0051] In a specific embodiment, a plurality of micron-wires formed by the magnetic confinement action of the parallel magnetic field can form a micron-wire array in the lumen of the fluid tube. Among them, the selected micron Fe3O4 particles have a morphology as Figure 2 (a) shown, with an average particle size of 136±62μm, as Figure 2 (b) shown. Figure 3 (a) and Figure 3 (b) show the micron-wire structure formed in the fluid tube and the arrangement of the micron-wires in the fluid tube, and the average size and average spacing of the formed micron-wires are 362±99μm (as Figure 3 (c) shown) and 981±260μm (as Figure 3 (d) shown), respectively. In the present invention, the micron-wire array plays a key role in the process of realizing position-selective loading of the catalyst: (1) The large size of the micron-wires is conducive to realizing the contact and collision of the fluid flow-induced with the specific surface of the micron-wires; (2) The large gap between the micron-wires not only allows the fluid with a high flow rate to flow through the micron-wire array quickly, but also does not cause mutual interference between the fluids flowing through the gaps between the micron-wires; (3) The micron-wire array has ultra-high hydraulic stability.

[0052] Figure 4 shows a schematic structural diagram of the system for implementing the disclosed method in the present invention. Combining Figure 4As shown, the second aspect of the present invention discloses a system for implementing the method disclosed in the first aspect of the present invention, which includes a fluid pipe 1, a catalyst carrier 4, and a pumping device 3. Among them, the lumen of the fluid pipe 1 forms a flow channel; the catalyst carriers 4 are configured in multiple numbers in the flow channel and are configured as a forest-like micro-wire array in the flow channel. The pumping device 3 is configured to be able to introduce a first solution containing a catalyst R for inducing the production of active reducing species into the flow channel at a specific flow rate. By means of the fluid flow inertia and the catalyst carrier steric effect, the first solution collides with and contacts the first surface of the catalyst carrier 4, so that the catalyst R for inducing the production of active reducing species is adsorbed on the first surface of the catalyst carrier 4 in the form of nano metal elemental particles to construct a catalytic reduction zone; and, after the introduction of the first solution, the pumping device 3 can also pump a second solution containing a catalyst O for inducing the production of active oxidizing species into the flow channel in the opposite direction at a corresponding specific flow rate. By means of the fluid flow inertia and the catalyst carrier steric effect, the second solution collides with and contacts the second surface of the catalyst carrier 4, so that the catalyst O is adsorbed on the second surface of the catalyst carrier 4 in the form of nano metal alloy particles to construct a catalytic oxidation zone; where the first surface is the surface of the catalyst carrier 4 facing the inflow direction of the first solution, and the second surface is the other surface of the catalyst carrier 4 opposite to the first surface.

[0053] Combined with Figure 5 (a) and Figure 5 (b), the manner in which different catalysts are selectively loaded on the same catalyst carrier in the present invention can be clearly understood. As Figure 5 (a) shows, first, at a specific flow rate of the first solution, Pd, as the catalyst R for inducing the production of active reducing species, adheres to the first surface of the catalyst carrier; subsequently, at a specific flow rate of the second solution, Pd-Au, as the catalyst O for inducing the production of active oxidizing species, adheres to the second surface of the catalyst. Among them, Figure 5 the arrow in (a) represents the flow direction of the first solution, Figure 5 the arrow in (b) represents the flow direction of the second solution. It can be seen from this that the flow directions of the first solution and the second solution are opposite, and the first surface to which Pd, as the catalyst R for inducing the production of active reducing species, adheres and the second surface to which Pd-Au, as the catalyst O for inducing the production of active oxidizing species, adheres are two mutually opposite surfaces on the catalyst carrier.

[0054] In an embodiment of the system disclosed in the second aspect of the present invention, it further includes a magnetic confinement device 2, which includes permanent magnets respectively arranged above and below the fluid pipe 1 to provide a parallel magnetic field perpendicular to the fluid pipe so that the micron Fe3O4 particles injected into the flow channel spontaneously form a micron wire array and are confined in the lumen by the magnetic field as the catalyst carrier 4.

[0055] In an embodiment of the system disclosed in the second aspect of the present invention, the catalyst carrier 4 is a micron wire array perpendicular to the flow channel formed by micron Fe3O4 particles under a parallel magnetic field, and the micron wire array extends along the flow channel direction.

[0056] The third aspect of the present invention discloses a use, specifically, the use of the method disclosed in the first aspect of the present invention and / or the system disclosed in the second aspect of the present invention for removing polyhalogenated organic pollutants in water treatment.

[0057] The fourth aspect of the present invention discloses a water catalytic treatment system, which includes the system disclosed in the second aspect of the present invention. Specifically, as Figure 6 shown, in this water catalytic treatment system, it includes a feed solution 5, a pumping device 3, a fluid pipe 1, and a catalyst carrier 4. Among them, the catalyst carrier 4 located in the fluid pipe 1 has constructed a catalytic reduction zone and a catalytic oxidation zone based on the method disclosed in the first aspect of the present invention and the system disclosed in the second aspect of the present invention. The feed solution 5 is pumped into the fluid pipe 1 under the operation of the pumping device 3, and successively flows through the catalytic reduction zone and the catalytic oxidation zone of the catalyst array, and successively alternates to perform reduction reactions and oxidation reactions, thereby removing polyhalogenated organic pollutants in the feed solution and realizing the purification treatment of the feed solution.

[0058] Among them, in a specific embodiment of the water catalytic treatment system, the pumping device 3 is set as a peristaltic pump. And, an electrolytic cell 6 is connected to the container of the feed solution 5 to supply H2 and O2 to the feed solution 5.

[0059] In addition, the fifth aspect of the present invention discloses a catalytic system, which includes a catalyst carrier 4 and a catalytic reduction zone and a catalytic oxidation zone constructed on the catalyst carrier 4; wherein, the catalytic reduction zone is formed by introducing a first solution containing a catalyst for generating active reducing species into the flow channel at a specific flow rate, and by means of the fluid flow inertia and the catalyst carrier steric effect, the first solution collides and contacts the first surface of the catalyst carrier 4, so that the catalyst R for inducing the generation of active reducing species is adsorbed on the first surface of the catalyst carrier 4 in the form of nano metal elemental particles; the first surface is the surface of the catalyst carrier 4 facing the inflow direction of the first solution; the formation method of the catalytic oxidation zone is that in the direction opposite to the fluid flow direction of the first solution, a second solution containing a catalyst for inducing the generation of active oxidation species is introduced into the flow channel at a corresponding specific flow rate, and by means of the fluid flow inertia and the catalyst carrier steric effect, the second solution collides and contacts the second surface of the catalyst carrier 4, so that the catalyst O is adsorbed on the second surface of the catalyst carrier 4 in the form of nano metal alloy particles; the second surface is the other surface of the catalyst carrier 4 opposite to the first surface.

[0060] In an embodiment of the catalytic system disclosed in the fifth aspect of the present invention, wherein the catalyst R for inducing the generation of active reducing species is a metal catalyst, which is selected from one or more of the following: Pt, Pd, Ni, such that the catalyst R for inducing the generation of active reducing species is attached to the first surface in the form of nano metal elemental particles.

[0061] In an embodiment of the catalytic system disclosed in the fifth aspect of the present invention, wherein the catalyst O for inducing the generation of active oxidizing species is a metal catalyst, which can specifically be Pd-Au mixed in proportion, such that the catalyst O for inducing the generation of active oxidizing species is attached to the second surface in the form of nano metal alloy particles.

[0062] Of course, regarding the attachment of the catalyst elemental or catalyst precursor to the surface of the catalyst carrier, it can be achieved through electrostatic adsorption generated in fluid flow, or can also be achieved by other acting forces, as long as the different catalysts for inducing reduction and inducing oxidation can be respectively attached to the corresponding specific surfaces.

[0063] In an embodiment of the catalytic system disclosed in the fifth aspect of the present invention, wherein the specific flow rate of the first solution can be set to 6-20 cm / s. In a particularly preferred embodiment, the specific flow rate of the first solution is set to 6.8 cm / s. Similarly, the corresponding specific flow rate of the second solution can also be set to 6-20 cm / s. In a particularly preferred embodiment, the corresponding specific flow rate of the second solution is set to 6.8 cm / s.

[0064] In an embodiment of the catalytic system disclosed in the fifth aspect of the present invention, wherein the first solution containing the catalyst R for inducing the generation of active reducing species is formed by adding the catalyst R for inducing the generation of active reducing species to deionized water; and / or, the second solution containing the catalyst O for inducing the generation of active oxidizing species is formed by adding the catalyst O for inducing the generation of active oxidizing species to deionized water. In a preferred embodiment of the catalytic system of the present invention, the catalyst R for inducing the generation of active reducing species is set to Pd, which exists in the first solution in the form of Pd 2+ ; while the catalyst for inducing the generation of active oxidizing species is set to Pd-Au, wherein Pd exists in the second solution in the form of Pd 2+ , and Au exists in the second solution in the form of Au 3+ . Pd 2+ in the first solution and Pd 2+ and Au 3+ in the second solution are first captured onto the surface of the negatively charged Fe3O4 micro wires through electrostatic adsorption and are reduced to nano metal particles by Fe3O4 under acidic conditions.

[0065] In an embodiment of the catalytic system disclosed in the fifth aspect of the present invention, the catalyst support 4 is a micron wire array formed by vertically arranging micron Fe3O4 particles under the action of magnetic confinement.

[0066] In an embodiment of the catalytic system disclosed in the fifth aspect of the present invention, a fluid tube 1 is further included. The lumen of the fluid tube 1 forms a flow channel. A plurality of micron wires of the catalyst support 4 are arranged along the extension direction of the flow channel, and there is a gap between the micron wires of adjacent catalyst supports 4.

[0067] In an embodiment of the catalytic system disclosed in the fifth aspect of the present invention, the fluid tube 1 is a rectangular tube; the catalyst support 4 is a micron wire array formed by micron Fe3O4 particles in the lumen under a parallel magnetic field, and the micron wire array extends perpendicular to the lumen and along the extension direction of the flow channel.

[0068] In the embodiments disclosed in the first to fifth aspects of the present invention, the active reducing species is preferably active hydrogen (·H), and the active oxidizing species is preferably hydroxyl radical (·OH). That is to say, in the present invention, the catalyst R is a catalyst for inducing the production of active hydrogen, preferably Pd, so as to construct a catalytic reduction zone on the first surface of the catalyst support; the catalyst O is a catalyst for inducing the production of hydroxyl radicals, preferably Pd-Au formed by mixing in proportion, so as to construct a catalytic oxidation zone on the second surface of the catalyst support.

[0069] The method, the system for implementing the method, the catalytic system and the water treatment system of the present invention will be introduced below using Pd as the catalyst for inducing the production of active reducing species and Pd-Au as the catalyst for inducing the production of active oxidizing species.

[0070] Among them, micron Fe3O4 particles with an average particle size of 136±62 μm are selected as the basis for constructing the catalyst support 4; with the help of palladium chloride (PdCl2, 98%), potassium tetrachloroaurate (KAuCl4, 98%) and deionized water, a first solution containing Pd and a second solution containing Pd-Au are constructed, and the first solution and the second solution can also be called precursor solutions. When verifying the results, the polyhalogenated organic pollutant used is 2,4-dichlorophenol (2,4-DCP, 98%). These materials and chemicals involved can all be purchased from the current commercial market.

[0071] In the system for implementing the method of the present invention, the fluid tube 1 used is a hollow rectangular quartz tube, and its size can be 150 mm in inner length, 6 mm in width, and 2 mm in height. The magnetic confinement device 2 includes two N52 rectangular permanent magnets, which are arranged in a coaxial parallel attraction mode. The tube body forming the flow channel is between the two permanent magnets, that is, the quartz tube is inserted into the gap between the two permanent magnets and remains parallel to the magnets. One end of the quartz tube is equipped with a three-way valve and a switching switch for collecting water samples. And a peristaltic pump is provided as the pumping device 3 to pump the first solution and the second solution into the flow channel in opposite directions respectively in sequence.

[0072] At the beginning, micron Fe3O4 particles are injected into the lumen of the quartz tube, and then a magnetic confinement device is constructed by means of permanent magnets arranged above and below the quartz tube to provide a parallel magnetic field perpendicular to the fluid tube so that the micron Fe3O4 particles in the lumen of the quartz tube spontaneously form a micron wire array as the catalyst carrier 4. Specifically, the formed micron wire array is composed of a plurality of micron wires perpendicular to the lumen and extending along the parallel magnetic induction lines to the top and bottom of the lumen, and the plurality of micron wires extend along the flow channel direction. The formation of the micron wire array as the catalyst carrier 4 can be realized by referring to the scheme disclosed in the patent WO2024 / 008124A1, which will not be elaborated here.

[0073] With the aid of the aforementioned system, in the method of the present invention, by means of the peristaltic pump as the pumping device 3, first, the first solution containing Pd 2+ is introduced into the flow channel at a specific flow rate of 6.8 cm / s, so that the first solution containing Pd 2+ rapidly flows through the micron wire array of the catalyst carrier 4. Due to the fluid flow inertia and the catalyst carrier steric effect, the first solution collides with the first surface of the micron wires of the catalyst carrier 4, thereby inducing the generation of active reducing species. The catalyst Pd is adsorbed on the first surface of the micron wires of the catalyst carrier 4 in the form of nano-metal single particles to construct a catalytic reduction zone; wherein the first surface is the surface of the micron wires of the catalyst carrier 4 facing the inflow direction of the first solution; then, the pumping operation of the first solution is stopped, and then, in the direction opposite to the fluid flow direction of the first solution, the second solution containing Pd 2+ -Au 3+ is introduced into the flow channel at a corresponding specific flow rate of 6.8 cm / s, so that the second solution containing Pd 2+ -Au 3+The second solution rapidly flows through the micro - wire array of the catalyst support 4. Due to the fluid - flow inertia and the steric - hindrance effect of the catalyst support, the second solution collides with and contacts the second surface of the micro - wires of the catalyst support 4, thereby inducing the generation of active oxygen species. Pd - Au is adsorbed on the second surface of the micro - wires of the catalyst support 4 in the form of nano - alloy particles to construct a catalytic oxidation region. Wherein the second surface is the other surface of the micro - wires of the catalyst support 4 opposite to the first surface.

[0074] The method of the present invention can also be described as follows: The realization of the selective construction of different catalysts at different surface positions of the same catalyst support in the present invention is based on the electrostatic adsorption - reduction mechanism. Specifically: Pd in the first solution 2+ and Pd in the second solution 2+ and Au 3+ are first captured on the surface of the negatively charged Fe3O4 micro - wire array through electrostatic attraction, and then reduced to nano - metal particles by Fe3O4 under acidic conditions. The specific operation process is as follows: By exposing the Fe3O4 support to Pd 2+ and / or Pd 2+ -Au 3+ precursor solutions for preparation: Using a peristaltic pump, Pd and / or Pd - Au are loaded onto the Fe3O4 micro - wire array at a flow rate of 6.8 cm / s, thereby preparing position - selective Pd&Pd - Au@Fe3O4 micro - wire arrays, position - selective Pd@Fe3O4 micro - wire arrays, and position - selective Pd - Au@Fe3O4 micro - wire arrays. Typically, to prepare a position - selective Pd&Pd - Au@Fe3O4 micro - wire array, first, micron - sized Fe3O4 particles (80 mg) are loaded into the inner cavity of a quartz tube, thereby spontaneously forming a forest - like micro - wire array. Then, the precursor solution of Pd 2+ is pumped into the lumen of the tube and flows through the Fe3O4 micro - wire array at a flow rate of 6.8 cm / s for 12 h. Immediately afterwards, the precursor solution of Pd 2+ -Au 3+ is pumped into the lumen of the tube and flows through the Fe3O4 micro - wire array at a flow rate of 6.8 cm / s for 12 h. After completing the second loading procedure, the loaded micro - wire array remains in the lumen for subsequent catalytic degradation tests and characterizations. In the present invention, the catalytic system formed based on this method is named the position - selective Pd&Pd - Au@Fe3O4 micro - wire array.

[0075] Based on the method of the present invention, two catalysts (i.e., Pd and Pd-Au) can be selectively loaded onto the first surface and the second surface of each micro-wire respectively, and are spatially separated, where the two surfaces are back-to-back in the spatial structure. When a solution dissolving H2 and O2 is pumped along the flow channel, it causes the main active substances ·H and ·OH to be generated on the first surface and the second surface of the selective Pd&Pd-Au@Fe3O4 micro-wire at each position respectively, and are generated alternately in sequence along the flow direction, thereby improving the catalytic degradation, dechlorination and mineralization efficiency of 2,4-DCP, which is much higher than the corresponding treatment efficiency in the non-position-selective Pd&Pd-Au@Fe3O4 micro-wire array system. The present invention opens up a broad prospect for the position-selective loading of catalysts on the surface of carriers, thus realizing the efficient and green purification of PHOPs in water.

[0076] In the present invention, different catalysts are loaded on different surfaces of the catalyst carrier 4 and catalytic reduction zones and catalytic oxidation zones are respectively formed in a spatially separated manner, which is achieved by means of the position-selective loading mechanism induced by high flow rate. Figure 5 (a) and Figure 5 (b) respectively show schematic diagrams of Pd and Pd-Au as two catalysts being selectively loaded onto two specific surfaces of each micro-wire successively. Combining Figure 5 (a) and Figure 5 (b), when the fluid containing the catalyst flows through the micro-wire in the lumen at a specific loading flow rate relatively fast, the flowing fluid tends to contact the upstream surface of the micro-wire rather than the downstream surface. This is the result of the combined action of fluid flow inertia and the steric hindrance effect of the micro-wire. The position-selective preference caused by the high-flow-rate flow makes the interaction (such as electrostatic adsorption) opportunity between the catalyst and the upstream surface higher than that with the downstream surface. In other words, more catalyst precursors are selectively loaded onto the upstream surface of the micro-wire (i.e., the catalyst carrier 4). Here, the upstream surface is referenced by the flow direction of the fluid. When loading the first solution, the first surface is the upstream surface, and the opposite second surface is the downstream surface; while when loading the second solution, the second surface of the catalyst carrier 4 is the upstream surface, and the opposite first surface is the downstream surface.

[0077] In order to verify this fluid flow-induced position preference, the present invention first used COMSOL Multiphysics 6.2 to perform computational fluid dynamics simulations. Figure 7 (a)-(e) show the adsorption distribution of the catalyst in the particle state on the surface of the catalyst carrier 4 at different fluid flow rates in the simulation analysis, where the black dots in the figure represent the model catalyst and the middle circle represents the catalyst carrier 4, Figure 7 (a) has a loading flow rate of 0.1 cm / s, Figure 7(b) The flow rate of the load is 2 cm / s, Figure 7 (c) The flow rate of the load is 4 cm / s, Figure 7 (d) The flow rate of the load is 7 cm / s, Figure 7 (e) The flow rate of the load is 10 cm / s. Among them, in Figure 7 (a), the particles are evenly distributed on the surface of the catalyst support 4 in a circular pattern. As the flow rate of the load increases, the model catalyst becomes increasingly concentrated on the first surface of the catalyst support 4, while there is no attachment of the model catalyst on the second surface of the catalyst support 4, as shown in Figure 7 (d) and Figure 7 (e). Based on the method of the present invention, the model catalyst is all attached to the first surface of the catalyst support 4, thereby realizing the position-selective loading of the catalyst. That is, Figure 7 (a)-(e) show the high-flow-rate-induced position-selective loading principle of loading the catalyst onto the micro-wire according to position. When the flow rate of the load is small (≤1.0 cm / s), the model catalyst is loaded on both the first surface and the second surface of the catalyst support 4, and the distribution is relatively uniform. When the flow rate of the load increases to 4 cm / s, the number of particles of the model catalyst loaded on the first surface is much larger than the number of particles loaded on the second surface. When the flow rate of the load increases to 7 cm / s, the particles are only loaded on the first surface and not on the second surface. Moreover, the greater the flow rate, the higher the position selectivity of the model catalyst adsorbed on the first surface of the catalyst support 4. All in all, the computational fluid dynamics simulation results confirm that the loading distribution of the model catalyst on the first surface and the second surface of the catalyst support 4 highly depends on the magnitude of the flow rate of the load.

[0078] To further confirm the above computational fluid dynamics simulation results, in the present invention, micro-titanium wires were also used as the model catalyst support, and the loading experiments of Pd and Au on the surface of the micro-titanium wires were carried out, where the distribution of Pd and Au on the first surface and the second surface of the micro-titanium wires highly depends on the magnitude of the flow rate of the load. Specifically, when a load flow rate of 8.0 cm / s is adopted, Pd in the solution 2+ is selectively enriched in the form of nanoparticles on the first surface of the micro-titanium wire, rather than on the second surface of the micro-titanium wire as shown in Fig. 8(a). Moreover, the second surface of the micro-titanium wire can be further used for selectively loading other catalysts (such as Au). The loading method is to replace the Pd 2+ solution with an Au 3+ solution and further reverse-pump the corresponding solution, then the Au in the solution 3+It is selectively enriched in the form of nanogold particles on the second surface of the micron titanium wire, as shown in Fig. 8(a). In contrast, when the loading flow rate is reduced to 0.3 cm / s, Pd and Au are uniformly distributed on the two surfaces of the micron titanium wire, that is, there is no position-selective enrichment of Pd and Au on the surface of the micron titanium wire, as shown in Figs. 9(a) and 9(b).

[0079] Based on the method of the present invention, it is possible to achieve position-selective loading of the target catalyst on two different surfaces of the micron wire. This high-flow-rate-induced position-selective loading provides new opportunities for constructing a spatially separated and orderly distributed catalyst structure, thereby providing potential for advanced purification processes such as cascade reactions in a micro-scale flow-through reactor.

[0080] Comparative experiment

[0081] First, flow-through catalytic experiment

[0082] For comparison, the following catalytic systems were constructed respectively:

[0083] ⅰ) Under the same loading conditions as described above, that is, under the same loading conditions as those for constructing the position-selective Pd&Pd-Au@Fe3O4 micron wire array, the position-selective Pd@Fe3O4 micron wire array and the position-selective Pd-Au@Fe3O4 micron wire array were prepared by pumping a single Pd and Pd-Au precursor solution through a peristaltic pump, that is, the position-selective Pd@Fe3O4 micron wire array loaded only with Pd and the position-selective Pd-Au@Fe3O4 micron wire array loaded only with Pd-Au. Figure 10 Shows the distribution of nano-Pd elemental particles on the surface of typical micron Fe3O4 particles constituting the position-selective Pd@Fe3O4 micron wire array. Figure 11 Shows the distribution of nano-Pd-Au alloy particles on the surface of typical micron Fe3O4 particles constituting the position-selective Pd-Au@Fe3O4 micron wire array.

[0084] ⅱ) The position-nonselective Pd&Pd-Au@Fe3O4 micron wire array was prepared at a lower loading flow rate (for example, 0.9 cm / s).

[0085] ⅲ) Uniformly distributed Pd&Pd-Au@Fe3O4 micron particles were prepared by a traditional batch adsorption method, which can expose all surfaces of the micron Fe3O4 particles to the Pd and Pd-Au precursor solutions equally, and then they were introduced into the flow channel to form a uniformly distributed Pd&Pd-Au@Fe3O4 micron wire array under the action of a parallel magnetic field. That is, it is not formed by the method of loading with a fluid at a specific speed disclosed in the present application, but by means of a traditional batch adsorption method.

[0086] Unless otherwise specified, all catalytic experiments were carried out on the aforementioned constructed catalytic system at a pressure of 0.83 ± 0.0 bar.

[0087] Specifically, as Figure 6 shown, the fluid tube 1 is connected to a pumping device 3 (i.e., a peristaltic pump), a glass container for the feed solution 5, and an electrolytic cell 6 through a conduit. The 2,4-DCP solution (10 mg / L, 50 mL, initial pH = 5.4 ± 0.1) in the glass container was first aerated with a mixed gas of H2 and O2 to remove the air in the catalytic system. Then the catalytic system was closed to increase the internal working pressure to a predetermined value (0.83 ± 0.01 bar) to increase the concentration of dissolved H2 and O2 in the 2,4-DCP solution. The pressurized 2,4-DCP solution was pumped into the fluid tube 1 along the Pd loading at a flow rate of 0.2 cm / s. At predetermined time intervals, water samples were collected downstream of the fluid tube 1 by switching the three-way valve connected to the fluid tube 1.

[0088] Second, experiment on the influence of the loading flow rate on the catalyst position distribution

[0089] First, attempts were made to selectively load Pd and Pd-Au on two surfaces of Fe3O4 microwires at a flow rate of 6.8 cm / s. The EDS elemental maps in Figures 12(a) and 12(b) visually confirmed the presence of a large number of Pd-rich Fe3O4 microparticles and Pd-Au-rich Fe3O4 microparticles in the position-selective Pd&Pd-Au@Fe3O4 microwire arrays, which are respectively one of the two most representative microparticles in the position-selective Pd&Pd-Au@Fe3O4 microwire arrays. For the Pd-rich Fe3O4 microparticles, Pd was selectively enriched on a part of its surface in the form of nano-sized metallic elemental particles, rather than the entire surface, as shown in Figure 12(a). For the Pd-Au-rich Fe3O4 microparticles, the distribution of Pd and Au on its surface also had a similar position selectivity, and the Pd distribution was in good agreement with the Au distribution, with a mass ratio of 1.1 ± 0.2:1, close to the predetermined value (1:1), existing in the form of nano-sized metal alloy particles, as shown in Figure 12(b).

[0090] However, when the loading flow rate was reduced to 0.9 cm / s, only Pd-Au-rich Fe3O4 microparticles were present in the position-nonselective Pd&Pd-Au@Fe3O4 microwire arrays, and the mass ratio of Pd to Au was 2.0 ± 0.1:1, which was greater than the corresponding mass ratio of the position-selective Pd&Pd-Au@Fe3O4 microwire arrays prepared under the loading flow rate condition of 6.8 cm / s (as Figure 13as shown). This is similar to the situation where only micron-sized Fe3O4 particles rich in Pd-Au appear after traditional batch adsorption( Figure 14 as shown). As can be understood by those skilled in the art, traditional batch adsorption only facilitates the uniform (rather than position-selective) adsorption of Pd and Pd-Au on the surface of micron-sized Fe3O4 particles. Therefore, the micron-sized Fe3O4 particles rich in Pd-Au produced by traditional batch adsorption method form a position-nonselective Pd&Pd-Au@Fe3O4 micron wire array in the magnetic confinement lumen.

[0091] This comparison demonstrates that position-selective Pd&Pd-Au@Fe3O4 microwires can be successfully prepared by a high-flow-induced position-selective loading strategy, highlighting the importance of fluid loading rate.

[0092] Effect experiment - The position-selective distribution of the catalyst promotes the catalytic degradation, dechlorination, and mineralization of 2,4-DCP

[0093] Figure 15(a) shows that even under the conditions of pressurized H2 and O2, the removal rate of bare (i.e., unloaded catalyst) Fe3O4 microwires for 2,4-DCP is only 25% within 6 h. In addition, the dechlorination and mineralization of 2,4-DCP are also quite limited (as shown in Figure 15(b) and Figure 15(b) respectively). These research results indicate that the catalytic activity and adsorption capacity of the catalyst support Fe3O4 for 2,4-DCP are limited.

[0094] However, after loading Pd and Pd-Au on the surface of Fe3O4 microwires based on the method disclosed in the present invention to form the catalytic system and catalytic system in the present invention, the catalytic degradation ability of 2,4-DCP under the conditions of pressurized H2 and O2 is significantly improved (Figure 15(a)), which indicates that Pd and Pd-Au can play a key role in driving the catalytic degradation of 2,4-DCP by activating H2 and O2. Moreover, the position-selective Pd&Pd-Au@Fe3O4 microwire array system can completely catalytically degrade 2,4-DCP within only 2 h, which has better catalytic performance than the position-selective Pd@Fe3O4 microwire array and the position-selective Pd-Au@Fe3O4 microwire array systems. This is attributed to the fact that the main active substances generated in the flow-through reactor of the position-selective Pd&Pd-Au@Fe3O4 microwire array are ·H and ·OH, which synergistically promote the catalytic degradation of 2,4-DCP.

[0095] Similarly, the catalytic degradation rate of the position-selective Pd&Pd-Au@Fe3O4 microline array system for 2,4-DCP within 2 h is higher than that of the position-nonselective Pd&Pd-Au@Fe3O4 microline array system and the uniformly distributed Pd&Pd-Au@Fe3O4 microline array system. These comparison results indicate that loading Pd and Pd-Au on the two surfaces of Fe3O4 microlines respectively can improve the catalytic degradation performance of 2,4-DCP. Obviously, compared with the position-nonselective Pd&Pd-Au@Fe3O4 microline array system and the uniformly distributed Pd&Pd-Au@Fe3O4 microline array system, the position-selective Pd&Pd-Au@Fe3O4 microline array system requires less Pd and Au loading and lower corresponding cost to achieve the same 2,4-DCP degradation rate. In summary, the flow-through reactor assembled with the position-selective Pd&Pd-Au@Fe3O4 microline array constructed by the present invention has the best catalytic degradation performance for 2,4-DCP.

[0096] Figure 15(b) shows a similar phenomenon in the dechlorination of 2,4-DCP. Specifically, the position-selective Pd&PdAu@Fe3O4 microline array system can achieve complete dechlorination of 2,4-DCP within only 2 h, while the dechlorination rate of 2,4-DCP in other catalytic systems does not exceed 69%. The dechlorination effect of 2,4-DCP in the catalytic system of the position-selective Pd&PdAu@Fe3O4 microline array is the best, which is related to the enhanced generation of ·H and ·OH in this system, and they synergistically promote the dechlorination of 2,4-DCP. Figure 16 The generation of ·H and ·OH under different atmosphere conditions in the catalytic system formed by the method of the present invention and other types of catalytic systems is shown. It can be seen that ·H and ·OH are significantly enhanced in the catalytic system of the position-selective Pd&PdAu@Fe3O4 microline array.

[0097] Similarly, the catalytic system of the position-selective Pd&PdAu@Fe3O4 microline array shows the highest 2,4-DCP mineralization rate (95%), which is at least 32% higher than the 2,4-DCP mineralization rate of other catalytic systems (Figure 15(c)). This enhanced mineralization rate is mainly due to the oxidation induced by the enhanced generation of ·OH and the dechlorination driven by the enhanced generation of ·H and ·OH. It is not difficult to understand that the mineralization degree of 2,4-DCP in the catalytic system of the position-selective Pd@Fe3O4 microline array is the lowest, only 11%, mainly because this system mainly generates ·H rather than ·OH.

[0098] As can be seen from the above comparison, the position-selective distribution of Pd and Pd-Au on the position-selective Pd&Pd-Au@Fe3O4 micro-wire arrays plays a key role in enhancing the catalytic degradation, dechlorination, and mineralization of 2,4-DCP. That is, under the high-flow fluid loading conditions of the present invention, the catalytic system formed by the position-selective loading of Pd and Pd-Au endows the two groups of catalysts with a spatially separated and alternately ordered structure, promoting the enhanced and sequential alternation of ·H and ·OH generation, and achieving efficient dehalogenation and deep mineralization of polyhalogenated organic pollutants.

[0099] For ease of description, spatial relative terms, such as "above", "on top of", "on the upper surface", "over", etc., may be used herein to describe the spatial positional relationship of one device or feature to other devices or features as shown in the figures. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "on top of" other devices or structures will then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the corresponding explanations of the spatial relative descriptions used herein will be made accordingly.

[0100] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of the described features, steps, operations, devices, components, and / or combinations thereof.

[0101] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented, for example, in an order other than those illustrated or described herein. In addition, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0102] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for site-selective loading of a catalyst based on fluid flow induction, characterized in that: The following steps are involved: S1, setting a flow channel and constructing a catalyst carrier having a forest-like micrometer wire array structure in the flow channel, wherein there are gaps between the micrometer wires of the catalyst carrier; S2, introducing a first solution containing a catalyst R for inducing the generation of active reducing species into a flow channel at a specific flow rate, and making the first solution collide and contact with a first surface of the catalyst carrier by means of fluid flow inertia and the steric effect of the catalyst carrier, so that the catalyst R contained therein is attached to the first surface of the catalyst carrier in the form of nano-metal elemental particles, so as to construct a catalytic reduction zone; wherein the first surface is a surface of the catalyst carrier facing the inflow direction of the first solution; S3, after step S2, in a direction opposite to the flow direction of the first solution, a second solution containing a catalyst O for inducing the generation of active oxidizing species is introduced into the flow channel at a corresponding specific flow rate, and the second solution is brought into collision contact with a second surface of the catalyst carrier by means of fluid flow inertia and a steric effect of the catalyst carrier, so that the catalyst O contained therein is attached to the second surface of the catalyst carrier in the form of nano-metal alloy particles, so as to construct a catalytic oxidation zone; wherein the second surface is another surface opposite to the first surface of the catalyst carrier; In step S1, a fluid tube is provided, wherein the lumen of the fluid tube forms the flow channel; Micron Fe3O4 particles are injected into the lumen, and with the help of a parallel magnetic field perpendicular to the flow channel, the micron Fe3O4 particles are driven to spontaneously form a magnetically constrained micron wire array in the lumen as a catalyst carrier, wherein the magnetically constrained micron wire array is a forest-like micron wire array that is perpendicular to the lumen and extends along the flow channel.

2. The method according to claim 1, characterized in that The catalyst R is a metal catalyst selected from one or more of the following: Pt, Pd, Ni, so that the catalyst R is attached to the first surface in the form of nano-metal single substance particles.

3. The method according to claim 1, characterized in that The catalyst O is a metal catalyst, which is Pd—Au mixed in a certain proportion, so that the catalyst O is attached to the second surface in the form of nano-metal alloy particles.

4. The method according to claim 1, characterized in that: The specific flow rate of the first solution and the corresponding specific flow rate of the second solution are both 6-20 cm / s.

5. A system for implementing the method according to any one of claims 1 to 4, characterized in that: include: a fluid tube, the lumen of which forms a flow channel; a catalyst carrier structured as a forest-like micron-wire array within the flow channel; A pumping device, which is configured to introduce a first solution containing a catalyst R for inducing the generation of active reducing species into a flow channel at a specific flow rate, and to make the first solution collide with a first surface of the catalyst carrier by means of fluid flow inertia and a catalyst carrier steric effect, so that the catalyst R contained therein is attached to the first surface of the catalyst carrier in the form of nano-metal single substance particles, so as to construct a catalytic reduction zone; Furthermore, after the first solution is introduced, the pumping device can introduce a second solution containing a catalyst O for inducing the generation of active oxidizing species into the flow channel at a corresponding specific flow rate in the opposite direction, and make the second solution collide and contact with the second surface of the catalyst carrier by means of the inertia of fluid flow and the steric effect of the catalyst carrier, so that the catalyst O contained therein is attached to the second surface of the catalyst carrier in the form of nano-metal alloy particles, so as to construct a catalytic oxidation zone; wherein the first surface is the surface of the catalyst carrier facing the direction of inflow of the first catalyst solution, and the second surface is another surface on the catalyst carrier opposite to the first surface; It also includes a magnetic confinement device, which includes permanent magnets respectively arranged above and below the fluid tube to provide a parallel magnetic field perpendicular to the fluid tube so that the micron Fe3O4 particles injected into the flow channel spontaneously form a micron wire array and are confined in the tube cavity by the magnetic field to serve as the catalyst carrier.

6. The system according to claim 5, characterized in that The catalyst carrier is a micron wire array perpendicular to the flow channel formed by micron Fe3O4 particles under a parallel magnetic field, and the micron wire array extends along the flow channel direction.

7. Use of the system according to claim 5 or 6 for removing polyhalogenated organic pollutants in water treatment.

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