Method and system for inducing catalyst position selective loading based on fluid flow

Abstract

The invention relates to a method and a system for inducing position selective loading of a catalyst based on fluid flow. The system is provided with a flow channel and a catalyst carrier which is positioned in the flow channel and has a forest-shaped micron linear array structure, a first solution containing a catalyst R for inducing generation of active reducing species and a second solution containing a catalyst O for inducing generation of active oxide are respectively introduced into the flow channel at a specific flow rate and in opposite directions; a catalyst R and a catalyst O are respectively loaded on two opposite specific surfaces of each microwire of a catalyst carrier by virtue of fluid flow inertia and a steric effect of the catalyst carrier, so as to construct a catalyst array which has spatial separation and extends along a flow channel direction in an R-O... R-O alternate distribution form; active hydrogen (. H) and hydroxyl radicals (. OH) are induced to be subjected to space-time separation and are sequentially and alternately generated in the flowing direction, and finally dynamic cascade synergistic dehalogenation mineralization and wastewater synergistic interaction treatment of the polyhalogenated organic pollutants are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a method for selectively loading catalyst positions based on fluid flow induction, which can selectively construct the loading position of the catalyst, realize the spatial separation of two catalysts with different properties on the same catalyst carrier, and thus enable the use of two catalysts with different properties on the catalyst carrier and can induce the temporal and spatial separation of ·H and ·OH and generate them alternately in sequence along the flow direction. The present invention also relates to a system, which can realize the method for constructing selective loading of catalyst positions based on fluid flow.

[0002] Furthermore, the present invention relates to the use of the method and system according to the invention for 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 pesticides, wood preservatives, herbicides and other fields for decades has led to serious pollution of water bodies and soil. As a class of priority controlled pollutants with characteristics such as high toxicity, environmental persistence and bioaccumulation, PHOPs have been restricted / prohibited from production and use, but their environmental pollution still persists and is frequently detected in water bodies and soil environments or even in the human body, attracting widespread attention from all over the world. Due to the low environmental content of PHOPs and the C–X (X represents halogen atoms) structure with high ionization energy, the removal effect of PHOPs by traditional biological and chemical sewage treatment units is very limited. In addition, these traditional treatment processes may accumulate small molecular intermediates, 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 residents' water use and promoting the construction of a healthy China.

[0004] Advanced Oxidation Processes (AOPs) are a technology that combines oxidants with activation strategies to utilize highly reactive oxidative species (such as OH, 1 O2) to achieve the degradation of organic pollutants. Among them, ·OH (E 0=2.7V) is considered to be one of the most oxidizing species. It can not only achieve PHOPs dehalogenation through the hydroxylation pathway, but also non-selectively mineralize PHOPs parent and its dehalogenation products (such as small molecular organic acids). Therefore, the development of ·OH-based AOPs technology is considered to be a promising PHOPs degradation technology and has been confirmed in many cases. Despite this, the ·OH-driven PHOPs degradation reaction is not only thermodynamically unfavorable, but also kinetically slow. This is attributed to the fact that halogen atoms are electron-withdrawing groups, which reduce the highest occupied molecular orbital energy of PHOPs, thereby inhibiting the electrophilic attack reaction of ·OH on C–X, making PHOPs hydroxylation and dehalogenation more difficult. Moreover, the more halogen atoms in PHOPs, the more significant the hindrance to the above-mentioned electrophilic attack reaction. To this end, many scholars have proposed strengthening strategies such as ·OH spatial confinement and energy input to improve the PHOPs hydroxylation, dehalogenation and mineralization performance, but none of them can fundamentally circumvent the originally unfavorable AOPs reaction. In contrast, active hydrogen (·H, E 0 =-2.3V) is a strong reducing species that can easily achieve PHOPs hydrodehalogenation through nucleophilic attack reactions on C–X, but the highly toxic dehalogenated products produced cannot be completely removed by ·H-driven hydrogenation reactions. It is noted that as the number of halogen atom substitutions decreases, the (partial) dehalogenated products of PHOPs become more resistant to ·H-driven hydrodehalogenation reactions, but become easier to ·OH-driven hydroxylation dehalogenation reactions. It can be seen that during the degradation process, with the change in the number of halogen atom substitutions, PHOPs parent pollutants and their dehalogenated products often show different or even opposite redox characteristics, resulting in a single (·OH) oxidation method or (·H) reduction method that cannot take into account the efficient dehalogenation mineralization of parent pollutants and dehalogenated products. Therefore, in order to achieve efficient dehalogenation mineralization of PHOPs, it is urgent to develop new degradation technologies that can meet the needs of efficient dehalogenation mineralization of PHOPs parent and their dehalogenated 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 based on fluid flow induction, comprising the following steps:

[0008] 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;

[0009] 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;

[0010] S3, after step S2, in the direction opposite to the flow direction of the first solution, a second solution containing a catalyst O for inducing the generation of active oxidative species is introduced into the flow channel at a corresponding specific flow rate, and the second solution is brought into collision 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 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.

[0011] Among them, in the present invention, each microwire in the forest-like microwire array structure can be regarded as a separate 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 microwire, and the catalyst O for inducing the production of active oxidizing species is selectively loaded on the second surface of the microwire, so that the catalytic reduction zone and the catalytic oxidation zone can be respectively constructed on the two opposite surfaces of the microwire.

[0012] According to the method disclosed in the first aspect of the present invention, 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.

[0013] According to the method disclosed in the first aspect of the present invention, 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.

[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 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 set, 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 to spontaneously form a magnetically constrained micron wire array in the lumen with the help of a parallel magnetic field perpendicular to the flow channel, 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, wherein the lumen of the fluid tube forms a flow channel, the catalyst carrier is constructed as a forest-like micron wire array in the flow channel, and the pumping device is constructed 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 by means of the fluid flow inertia and the catalyst carrier steric effect, the first solution is collided with the first surface of the catalyst carrier, so that the catalyst 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; and the pumping device can, after the first solution is introduced, 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 by means of the fluid flow inertia and the catalyst carrier steric effect, the second solution is collided with the second surface 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.

[0017] According to the system disclosed in the second aspect of the present invention, 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.

[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 in 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 according to the second aspect of the present invention.

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

[0022] The technical solution of the present invention is disclosed in detail below in conjunction with the embodiments shown in the accompanying drawings and the accompanying drawing numbers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of the steps of the method of the present invention is shown.

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

[0025] Figure 3 (a)-(d) show the morphology, distribution, average size and average spacing of the formed microwires of a magnetically confined microwire array composed of micron Fe3O4 particles as a catalyst carrier in a fluid tube.

[0026] Figure 4 A schematic diagram of a system device for realizing site-selective loading of a catalyst in the disclosed method in the present invention is shown.

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

[0028] Figure 6 The schematic diagram of the device 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 microwire at different load flow rates and the simulation diagram of the adsorption distribution of the model catalyst particles by the microwire.

[0030] Figures 8(a) and 8(b) show the Pd and Au morphologies and element distributions of the first and second surfaces of titanium wire as a catalyst support at a high loading flow rate.

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

[0032] Fig.10 The Pd morphology and element distribution diagram on the surface of a typical micron Fe3O4 particle of a composition position selective Pd@Fe3O4 micron line array prepared based on the method of the present invention are shown.

[0033] Fig.11 The Pd-Au morphology and element distribution diagram on the surface of a typical micron Fe3O4 particle of a composition position selective Pd-Au@Fe3O4 micron line array prepared based on the method of 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 micron-line array prepared based on the method of the present invention.

[0035] Fig.13 The Pd and Pd-Au morphologies and element distributions on the surface of typical micron-Fe3O4 particles of the position-non-selective Pd&Pd-Au@Fe3O4 micron-wire array prepared at a low loading flow rate are shown.

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

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

[0038] Fig.16 The production of ·H and ·OH in the catalytic system formed based on the method of the present invention and other catalytic systems under different atmosphere conditions is shown. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0041] Figure 1 The flowchart of the steps of the method of the present invention is shown. Figure 1 As shown, the first aspect of the present invention discloses a method for position-selective loading of a catalyst based on fluid flow induction, comprising the following steps:

[0042] 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;

[0043] 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;

[0044] S3, after step S2, in the direction opposite to the flow direction of the first solution, a second solution containing a catalyst O for inducing the generation of active oxidative species is introduced into the flow channel at a corresponding specific flow rate, and the second solution is brought into collision 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 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.

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

[0046] In an embodiment of the method, 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 of the catalyst carrier in the form of nano-metal single substance particles.

[0047] In an embodiment of the method, 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 of the catalyst carrier 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 to be different.

[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 catalyst precursor 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 catalyst precursor 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 is Pd 2+ The catalyst O used to induce the generation of active oxidative species is set to be a mixture of Pd-Au in a certain proportion, wherein Pd is in the form of Pd 2+exists in the second solution in the form of Au 3+ The first solution contains Pd 2+ and Pd in ​​the second solution 2+ and Au 3+ First, it is captured by electrostatic adsorption on the surface of negatively charged Fe3O4 micron wires, and is reduced to nano metal particles by Fe3O4 under acidic conditions. Of course, it should be understood by those skilled in the art that, in the present invention, catalyst R and catalyst O can also be catalyst simple particles, for example, catalyst R can be Pd simple substance. In addition, about the attachment of catalyst simple substance or catalyst precursor to the catalyst carrier surface, it can be achieved by electrostatic adsorption, and it can also be achieved by other forces, as long as it can be achieved that the induced generation of active reduction species and the induced generation of active oxidation species are attached to the corresponding specific surfaces with different catalysts.

[0050] In an embodiment of the method, in step S1, a fluid tube is provided, the lumen of the fluid tube forming 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 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.

[0051] In a specific embodiment, a plurality of micrometer wires formed by the magnetic confinement of a parallel magnetic field can form a micrometer wire array in the lumen of the fluid tube. Figure 2 As shown in (a), the average particle size is 136±62 μm. Figure 2 (b) as shown. Figure 3 (a) and Figure 3 (b) shows the microwire structure formed in the fluid tube and the arrangement of the microwires in the fluid tube, and the average size and average spacing of the formed microwires are 362±99μm (as shown in FIG. Figure 3 (c)) and 981±260μm (as shown in Figure 3 (d)). In the present invention, the microwire array plays a key role in achieving position-selective catalyst loading: (1) The large size of the microwire is conducive to the fluid flow inducing its contact and collision with the specific surface of the microwire; (2) The large gaps between the microwires not only allow the high-flow fluid to flow through the microwire array quickly, but also do not cause mutual interference between the fluids flowing through the gaps between the microwires; (3) The microwire array has ultra-high hydraulic stability.

[0052] Figure 4 The structure diagram of the system used to implement the disclosed method in the present invention is shown. 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 tube 1, a catalyst carrier 4 and a pumping device 3, wherein the lumen of the fluid tube 1 forms a flow channel; the catalyst carrier 4 is configured as a plurality of catalyst carriers 4 in the flow channel, and is configured as a forest-like micron 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 generation of active reducing species into the flow channel at a specific flow rate, and by means of the inertia of fluid flow and the steric effect of the catalyst carrier, the first solution is collided with 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 catalyst carrier 4 in the form of nano-metal single substance particles. The first surface of the catalyst carrier 4 is used to construct a catalytic reduction zone; and the pumping device 3 can also, after the introduction of the first solution, pump 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 the opposite direction, and make the second solution collide and contact with the second surface of the catalyst carrier 4 by means of the fluid flow inertia and the steric effect of the catalyst carrier, so that the catalyst O is adsorbed on the second surface of the catalyst carrier 4 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 4 facing the inflow direction of the first solution, and the second surface is another surface on the catalyst carrier 4 opposite to the first surface.

[0053] Combination 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. Figure 5 As shown in (a), first, at a specific flow rate of the first solution, Pd as a catalyst R for inducing the generation of active reducing species is attached to the first surface of the catalyst support; then, at a specific flow rate of the second solution, Pd-Au as a catalyst O for inducing the generation of active oxidizing species is attached to the second surface of the catalyst. Figure 5 The arrows in (a) indicate the flow direction of the first solution. Figure 5 The arrow in (b) indicates the flow direction of the second solution, from which it can be seen that the flow direction of the first solution is opposite to that of the second solution, and the first surface to which Pd, which is a catalyst R for inducing the production of active reducing species, is attached and the second surface to which Pd-Au, which is a catalyst O for inducing the production of active oxidizing species, is attached are two surfaces on the catalyst carrier facing away from each other.

[0054] In an embodiment of the system disclosed in the second aspect of the present invention, it also includes a magnetic confinement device 2, which includes permanent magnets respectively arranged above and below the fluid tube 1, so as 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, serving 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 micrometer wire array perpendicular to the flow channel formed by micrometer Fe3O4 particles under a parallel magnetic field, and the micrometer 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 in 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, Figure 6 As shown, the water catalytic treatment system includes a feed solution 5, a pumping device 3, a fluid pipe 1 and a catalyst carrier 4, wherein 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 flows through the catalytic reduction zone and the catalytic oxidation zone of the catalyst array in turn, and performs reduction reaction and oxidation reaction alternately in turn, thereby removing polyhalogenated organic pollutants in the feed solution and realizing the purification treatment of the feed solution.

[0058] In a specific embodiment of the water catalytic treatment system, the pumping device 3 is configured as a peristaltic pump. In addition, an electrolytic cell 6 is connected to the container of the feed solution 5 to supply H 2 and O 2 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 producing active reducing species into a flow channel at a specific flow rate, and making the first solution collide and contact with the first surface of the catalyst carrier 4 by means of the fluid flow inertia and the catalyst carrier steric effect, 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 element particles; wherein the first surface is the surface of the catalyst carrier 4 facing the inflow direction of the first solution; the catalytic oxidation zone is formed by introducing a second solution containing a catalyst for inducing the production of active oxidizing species into the flow channel at a corresponding specific flow rate in the direction opposite to the fluid flow direction of the first solution, and making the second solution collide and contact with the second surface of the catalyst carrier 4 by means of the fluid flow inertia and the catalyst carrier steric effect, 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 another 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, the catalyst R for inducing the production of active reducing species is a metal catalyst selected from one or more of the following: Pt, Pd, Ni, so that the catalyst R for inducing the production of active reducing species is attached to the first surface in the form of nano-metal element particles.

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

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

[0063] In an embodiment of the catalytic system disclosed according to the fifth aspect of the present invention, 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.

[0064] In an embodiment of the catalytic system disclosed according to the fifth aspect of the present invention, 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 is Pd 2+ exists in the first solution in the form of; and the catalyst for inducing the generation of active oxidative species is set to Pd-Au, wherein Pd is in the form of Pd 2+ exists in the second solution in the form of Au 3+ The first solution contains Pd 2+ and Pd in ​​the second solution 2+ and Au 3+ First, it is captured on the negatively charged Fe3O4 microwire surface by electrostatic adsorption and then 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 carrier 4 is a micron wire array formed by vertical arrangement of micron Fe3O4 particles under magnetic confinement.

[0066] In an embodiment of the catalytic system disclosed in the fifth aspect of the present invention, it also includes a fluid tube 1, the tube cavity of the fluid tube 1 forms a flow channel, the micron wires of the catalyst carrier 4 are constructed in multiple numbers along the extension direction of the flow channel, and there are gaps between the micron wires of adjacent catalyst carriers 4.

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

[0068] In the embodiments disclosed in the first aspect to the fifth aspect 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, in the present invention, the catalyst R is a catalyst that induces the generation of active hydrogen, preferably Pd, so that a catalytic reduction zone is constructed on the first surface of the catalyst carrier; the catalyst O is a catalyst that induces the generation of hydroxyl radicals, preferably Pd-Au formed by mixing in proportion, so that a catalytic oxidation zone is constructed on the second surface of the catalyst carrier.

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

[0070] Among them, micron Fe3O4 particles with an average particle size of 136±62μm are selected as the basis for constructing the catalyst carrier 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, wherein 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 150mm in inner length × 6mm in width × 2mm in height. The magnetic confinement device 2 includes two N52 rectangular permanent magnets, which are arranged in a coaxial parallel attraction mode, and 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. A three-way valve is installed at one end of the quartz tube, and a switching switch is provided for collecting water samples. A peristaltic pump is provided as a pumping device 3 to pump the first solution and the second solution into the flow channel in sequence in opposite directions.

[0072] At the beginning, micron Fe3O4 particles are injected into the lumen of the quartz tube, and then a magnetic confinement device is constructed with the help 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 a catalyst carrier 4. Specifically, the formed micron wire array is composed of a plurality of micron wires that are perpendicular to the lumen and extend to the top and bottom of the lumen along parallel magnetic flux lines, and the plurality of micron wires extend along the flow channel direction. The formation of the micron wire array as a catalyst carrier 4 can be achieved with the help of the scheme disclosed in patent WO2024 / 008124A1, which will not be repeated here.

[0073] With the aid of the above system, in the method of the present invention, a peristaltic pump as the pumping device 3 is first used to pump a Pd-containing 2+ The first solution of Pd was introduced into the flow channel at a specific flow rate of 6.8 cm / s. 2+ The first solution quickly flows through the micron wire array of the catalyst carrier 4, and the first solution collides and contacts with the first surface of the micron wire of the catalyst carrier 4 by means of the inertia of fluid flow and the steric effect of the catalyst carrier, thereby inducing the generation of active reducing species. The catalyst Pd is adsorbed on the first surface of the micron wire of the catalyst carrier 4 in the form of nano-metal element particles to construct a catalytic reduction zone; wherein the first surface is the surface of the micron wire of the catalyst carrier 4 facing the inflow direction of the first solution; then, the pumping of the first solution is stopped, and then the Pd-containing catalyst is pumped into the catalyst carrier 4 in the opposite direction to the flow direction of the first solution. 2+ -Au 3+ The second solution containing Pd was introduced into the flow channel at a specific flow rate of 6.8 cm / s. 2+ -Au 3+The second solution quickly flows through the micron wire array of the catalyst carrier 4, and the second solution collides and contacts with the second surface of the micron wire of the catalyst carrier 4 by means of the inertia of fluid flow and the steric effect of the catalyst carrier, thereby inducing the generation of active oxidative species. Pd-Au is adsorbed on the second surface of the micron wire of the catalyst carrier 4 in the form of nano-alloy particles to construct a catalytic oxidation zone; wherein the second surface is another surface of the micron wire of the catalyst carrier 4 opposite to the first surface.

[0074] The method of the present invention can also be described as follows: The selective construction of different catalysts on different surface positions of the same catalyst carrier in the present invention is based on an electrostatic adsorption-reduction mechanism, specifically: Pd 2+ and Pd in ​​the second solution 2+ and Au 3+ First, they are captured on the negatively charged Fe3O4 micron wire array surface by electrostatic attraction, and then reduced to nano-metal particles by Fe3O4 under acidic conditions. 2+ and / or Pd 2+ -Au 3+ Preparation in precursor solution: Pd and / or Pd-Au were loaded onto the Fe3O4 micron wire array using a peristaltic pump at a flow rate of 6.8 cm / s, thereby preparing position-selective Pd&Pd-Au@Fe3O4 micron wire arrays, position-selective Pd@Fe3O4 micron wire arrays, and position-selective Pd-Au@Fe3O4 micron wire arrays. Typically, in order to prepare position-selective Pd&Pd-Au@Fe3O4 micron wire arrays, micron Fe3O4 particles (80 mg) were first loaded into the inner cavity of a quartz tube, thereby spontaneously forming a forest-like micron wire array. Then, Pd was loaded onto the Fe3O4 micron wire array at a load flow rate of 6.8 cm / s. 2+ The precursor solution was pumped into the lumen and flowed through the Fe3O4 microwire array for 12 h. Then, Pd 2+ -Au 3+ The precursor solution is pumped into the lumen and flows through the Fe3O4 micron wire array for 12 hours; after the second loading procedure is completed, the loaded micron wire array remains in the lumen for subsequent catalytic degradation testing and characterization. In the present invention, the catalytic system formed based on this method is named as position-selective Pd&Pd-Au@Fe3O4 micron wire array.

[0075] Based on the method of the present invention, two catalysts (i.e., Pd and Pd-Au) can be selectively loaded on the first surface and the second surface of each micrometer wire, respectively, and are separated in space, wherein the two surfaces are opposite to each other in spatial structure. When a solution dissolving H2 and O2 is pumped along the flow channel, the main active substances ·H and ·OH are respectively generated on the first surface and the second surface of each position-selective Pd&Pd-Au@Fe3O4 micrometer wire, and are alternately generated 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 position-nonselective Pd&Pd-Au@Fe3O4 micrometer wire array system. The present invention opens up a promising path for the position-selective loading of catalysts on the carrier surface, thereby realizing 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 to form spatially separated catalytic reduction zones and catalytic oxidation zones, respectively, which is achieved by means of a position-selective loading mechanism induced by a high flow rate. Figure 5 (a) and Figure 5 (b) shows a schematic diagram of Pd and Pd-Au as two catalysts selectively loaded on two specific surfaces of each micrometer wire. Figure 5 (a) and Figure 5 (b), when the fluid containing the catalyst flows through the microwire in the lumen at a faster rate than a specific load flow rate, the flowing fluid is more inclined to contact the upstream surface of the microwire rather than the downstream surface of the microwire. This is the result of the combined effect of the fluid flow inertia and the microwire steric effect. The positional selectivity caused by high flow rate flow makes the interaction between the catalyst and the upstream surface (such as electrostatic adsorption) more likely than the interaction with the downstream surface. In other words, more catalyst precursors are selectively loaded onto the upstream surface of the microwire (i.e., the catalyst carrier 4). The upstream surface here is referenced to the flow direction of the fluid. When the first solution is loaded, the first surface is the upstream surface, and the opposite second surface is the downstream surface; when the second solution is loaded, 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 firstly used COMSOL Multiphysics 6.2 to perform computational fluid dynamics simulation. Figure 7 (a)-(e) show the adsorption distribution of the catalyst in 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) The load flow rate is 0.1 cm / s, Figure 7(b) The load flow rate is 2 cm / s, Figure 7 (c) The load flow rate is 4 cm / s, Figure 7 (d) The load flow rate is 7 cm / s, Figure 7 (e) The load flow rate is 10 cm / s. Figure 7 In (a), the particles are evenly distributed on the surface of the catalyst carrier 4 around the circumference, and as the loading flow rate increases, the model catalyst is increasingly enriched on the first surface of the catalyst carrier 4, while the second surface of the catalyst carrier 4 has no model catalyst attached at all. Figure 7 (d) and Figure 7 (e) As shown. Based on the method of the present invention, the model catalyst is completely attached to the first surface of the catalyst carrier 4, thereby achieving position-selective loading of the catalyst. That is, Figure 7 (a)-(e) show the principle of high flow rate induced position selective loading of the catalyst onto the micron line by position selection. When the load flow rate is small (≤1.0cm / s), the model catalyst is loaded on both the first surface and the second surface of the catalyst carrier 4, and the distribution is relatively uniform. When the load flow rate increases to 4cm / s, the number of particles loaded on the first surface by the model catalyst is much larger than the number of particles loaded on the second surface, and when the load flow rate increases to 7cm / 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 carrier 4. In summary, the computational fluid dynamics simulation results confirm that the load distribution of the model catalyst on the first surface and the second surface of the catalyst carrier 4 is highly dependent on the load flow rate.

[0078] In order to further confirm the above computational fluid dynamics simulation results, in the present invention, micron titanium wire was used as a model catalyst carrier to carry out Pd and Au loading experiments on the surface of micron titanium wire, in which the distribution of Pd and Au on the first surface and the second surface of the micron titanium wire is highly dependent on the loading flow rate. Specifically, when the loading flow rate is 8.0 cm / s, the Pd 2+ The nanoparticles are selectively enriched on the first surface of the micron titanium wire, but not on the second surface of the micron titanium wire, as shown in FIG8(a). Moreover, the second surface of the micron titanium wire can be further used to selectively load other catalysts (such as Au) by adding Pd 2+ Solution replaced with Au 3+ solution, and further reverse pumping the corresponding solution, so that Au in the solution 3+The nano-gold particles are selectively enriched on the second surface of the micron titanium wire, as shown in Figure 8 (a). In contrast, when the load flow rate is reduced to 0.3 cm / s, Pd and Au are evenly 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 Figures 9 (a) and 9 (b).

[0079] Based on the method of the present invention, the position-selective loading of the target catalyst can be achieved on two different surfaces of the micrometer wire. This high flow rate-induced position-selective loading provides new opportunities for constructing spatially separated and orderly distributed catalyst structures, thereby providing potential for advanced purification processes such as cascade reactions in microscale flow-through reactors.

[0080] Comparative experiment

[0081] First, flow-through catalytic experiment

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

[0083] ⅰ) Under the same loading conditions as mentioned above, i.e., under the same loading conditions as for constructing the position selective Pd&Pd-Au@Fe3O4 micron wire array, a single Pd and Pd-Au precursor solution was pumped by a peristaltic pump to prepare the position selective Pd@Fe3O4 micron wire array and the position selective Pd-Au@Fe3O4 micron wire array, i.e., 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, respectively. Fig.10 The distribution of nano-Pd single-element particles on the surface of typical micron-Fe3O4 particles that constitute the site-selective Pd@Fe3O4 micron-wire array is shown. Fig.11 Shown is the distribution of nano-Pd-Au alloy particles on the surface of typical micron-Fe3O4 particles that constitute the site-selective Pd-Au@Fe3O4 micron-wire array.

[0084] ii) Position-nonselective Pd&Pd-Au@Fe3O4 microwire arrays were prepared at a lower loading flow rate (e.g., 0.9 cm / s).

[0085] iii) Prepare uniformly distributed Pd & Pd-Au @ Fe3O4 micron particles by conventional batch adsorption method, which can expose all surfaces of micron Fe3O4 particles to Pd and Pd-Au precursor solutions equally, and then introduce them into the flow channel to form uniformly distributed Pd & Pd-Au @ Fe3O4 micron line arrays under the action of parallel magnetic fields. That is, it is not formed by the method disclosed in this application, which is to load the fluid at a specific speed, but by conventional batch adsorption method.

[0086] Unless otherwise stated, all catalytic experiments were performed at a pressure of 0.83 ± 0.0 bar on a catalytic system equipped with the aforementioned configuration.

[0087] Specifically, Figure 6 As shown, the fluid tube 1 is connected to the pumping device 3 (i.e., peristaltic pump), the glass container of the feed solution 5, and the 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 is first aerated with a mixed gas of H2 and O2 to remove the air in the catalytic system. Then the catalytic system is closed and its internal working pressure is raised to a predetermined value (0.83 ± 0.01 bar) to increase the concentration of H2 and O2 dissolved in the 2,4-DCP solution. The pressurized 2,4-DCP solution is pumped into the fluid tube 1 along the Pd load flow direction at a flow rate of 0.2 cm / s. At a predetermined time interval, the water sample is collected downstream of the fluid tube 1 by switching the three-way valve connected to the fluid tube 1.

[0088] Second, the effect of load flow rate on the distribution of catalyst positions

[0089] First, we tried to selectively load Pd and Pd-Au on the two surfaces of Fe3O4 micron wires at a flow rate of 6.8 cm / s. The EDS elemental spectra in Figures 12(a) and 12(b) intuitively confirmed that there were a large number of Pd-rich micron Fe3O4 particles and Pd-Au-rich micron Fe3O4 particles in the position-selective Pd&Pd-Au@Fe3O4 micron wire array, and they were one of the two most representative micron particles in the position-selective Pd&Pd-Au@Fe3O4 micron wire array. For the Pd-rich micron Fe3O4 particles, Pd was selectively enriched on part of its surface in the form of nano-metal single-substance particles, rather than on the entire surface, as shown in Figure 12(a). For Pd-Au-rich micron Fe3O4 particles, the distribution of Pd and Au on their surfaces also has similar positional selectivity, and the Pd distribution is well consistent with the Au distribution, with a mass ratio of 1.1±0.2:1, close to the predetermined value (1:1), and exists in the form of nano-metal alloy particles, as shown in Figure 12(b).

[0090] However, when the loading flow rate is reduced to 0.9 cm / s, only Pd-Au-rich micron Fe3O4 particles exist in the position-nonselective Pd&Pd-Au@Fe3O4 micron wire array, and the mass ratio of Pd to Au is 2.0±0.1:1, which is larger than the corresponding mass ratio of the position-selective Pd&Pd-Au@Fe3O4 micron wire array prepared under the loading flow rate of 6.8 cm / s (e.g. Fig.13This is similar to the situation where only Pd-Au-rich micronized Fe3O4 particles appear after conventional batch adsorption ( Fig.14 As can be understood by those skilled in the art, conventional batch adsorption is only conducive to the uniform (but not position-selective) adsorption of Pd and Pd-Au on the surface of micron Fe3O4 particles. Therefore, the Pd-Au-rich micron Fe3O4 particles produced by the conventional batch adsorption method form a position-non-selective Pd&Pd-Au@Fe3O4 micron line array in the magnetic confinement cavity.

[0091] This comparison demonstrates that site-selective Pd&Pd-Au@Fe3O4 microwires can be successfully prepared via a high-flow-induced site-selective loading strategy, emphasizing the importance of fluid loading speed.

[0092] Effect experiment - Catalyst site-selective distribution promotes catalytic degradation, dechlorination and mineralization of 2,4-DCP

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

[0094] After Pd and Pd-Au were loaded on the surface of Fe3O4 microwires based on the method disclosed in the present invention to form the catalytic system and catalytic system of the present invention, the catalytic degradation ability of 2,4-DCP under pressurized H2 and O2 conditions was 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 in just 2 hours, which is better than the catalytic performance of the position-selective Pd@Fe3O4 microwire array and the position-selective Pd-Au@Fe3O4 microwire array system. This is attributed to the fact that the main active substances produced 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 2,4-DCP by the position-selective Pd&Pd-Au@Fe3O4 microwire array system within 2 h was higher than that by the position-nonselective Pd&Pd-Au@Fe3O4 microwire array system and the uniformly distributed Pd&Pd-Au@Fe3O4 microwire array system. These comparison results indicate that loading Pd and Pd-Au on the two surfaces of Fe3O4 microwires, respectively, can improve the catalytic degradation performance of 2,4-DCP. Obviously, compared with the position-nonselective Pd&Pd-Au@Fe3O4 microwire array system and the uniformly distributed Pd&Pd-Au@Fe3O4 microwire array system, the position-selective Pd&Pd-Au@Fe3O4 microwire array system requires less Pd and Au loading to obtain the same 2,4-DCP degradation rate, and the corresponding cost is also lower. In summary, the flow-through reactor assembled with the position-selective Pd&Pd-Au@Fe3O4 micron wire array constructed by the present invention has the best catalytic degradation performance for 2,4-DCP.

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

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

[0098] From the above comparison, it can be seen that the position-selective distribution of Pd and Pd-Au on the position-selective Pd&Pd-Au@Fe3O4 micron wire array plays a key role in enhancing the catalytic degradation, dechlorination and mineralization of 2,4-DCP. That is, the catalytic system formed by the position-selective loading of Pd and Pd-Au under the high-flow fluid loading conditions of the present invention gives the two groups of catalysts a spatially separated and alternating ordered structure, which promotes the enhanced and alternating generation of ·H and ·OH, and realizes the efficient dehalogenation and deep mineralization of polyhalogenated organic pollutants.

[0099] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted 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 indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of 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 the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0102] The above are only 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 modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in 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 the direction opposite to the flow direction of the first solution, a second solution containing a catalyst O for inducing the generation of active oxidative species is introduced into the flow channel at a corresponding specific flow rate, and the second solution is brought into collision 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 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.

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. The method according to claim 1, characterized in that 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.

6. A system for implementing the method according to any one of claims 1 to 5, 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 production 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 fluid flow inertia 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 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.

7. The system according to claim 6, characterized in that 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.

8. The system according to claim 7, 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.

9. Use of the method according to any one of claims 1 to 5 and / or the system according to any one of claims 6 to 8 for removing polyhalogenated organic pollutants in water treatment.

10. A water catalytic treatment system, characterized in that: The water catalytic treatment system includes a system according to any one of claims 6-8.

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