Conductive catalytic hydrophobic membrane, method for preparing same, and use thereof

Abstract

The application provides a conductive catalytic hydrophobic membrane, which comprises a conductive layer, a catalytic layer and a hydrophobic membrane, wherein the catalytic layer is loaded on the conductive layer to form a conductive catalytic layer; and the conductive catalytic layer is loaded on the hydrophobic membrane to form the conductive catalytic hydrophobic membrane. The conductive catalytic hydrophobic membrane is applied to the treatment of ammonia-nitrogen-containing wastewater, coupling of membrane separation and an electrochemical process, so that the conductive catalytic hydrophobic membrane has the characteristics of strong anti-pollution ability and high ammonia recovery efficiency, and has important significance for widening the range of membrane technology in the field of water treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of functional membrane separation technology and water treatment, and more particularly, to a conductive catalytic hydrophobic membrane and a preparation method and application thereof. BACKGROUND

[0002] With the increasing of world population, the advancing of urbanization rate and industrialization process, more and more high ammonia-nitrogen wastewater is discharged into the water environment, which has an important impact on human health and ecological environment dynamic balance.

[0003] At present, there are many processes for removing and recovering ammonia-nitrogen, such as biological methods such as AO, AAO, physical methods such as stripping, reverse osmosis, ion exchange membrane adsorption, and chemical methods such as chemical precipitation. Since the concept of zero discharge was proposed, membrane ammonia removal technology with membrane separation as the core has been welcomed in the treatment of industrial wastewater due to its small occupation, high treatment efficiency and high ammonia recovery rate.

[0004] The traditional membrane ammonia removal technology mainly adds an alkaline agent to the membrane ammonia removal system, the alkaline agent reacts with water to generate hydroxyl ions, the hydroxyl ions react with ammonium ions to generate ammonia gas, and then the ammonia gas is separated and recovered by permeating through the hydrophobic membrane under the driving of the vapor pressure. However, the traditional membrane ammonia removal process adds alkaline agents such as sodium hydroxide and quicklime, which brings additional agent cost, and the added alkaline agents are also easy to cause membrane fouling, membrane wetting and other phenomena, affecting the ammonia recovery effect and the service life of the membrane. SUMMARY

[0005] Therefore, the present application provides a conductive catalytic hydrophobic membrane and a preparation method and application thereof, so that the conductive catalytic hydrophobic membrane couples the membrane separation and the electrochemical process in the membrane ammonia removal system, does not need to add an alkaline agent, generates hydroxyl ions in situ at the interface of the conductive catalytic hydrophobic membrane by the action of an external voltage, reacts with ammonium ions in ammonia-nitrogen wastewater to generate ammonia gas and recovers ammonia. The conductive catalytic hydrophobic membrane has the characteristics of strong anti-pollution ability and high ammonia recovery efficiency, and has important significance for widening the range of membrane technology in the field of water treatment.

[0006] According to an aspect of the present application, a conductive catalytic hydrophobic membrane is provided, comprising: a conductive layer, a catalytic layer and a hydrophobic membrane, wherein the catalytic layer is loaded on the conductive layer to form a conductive catalytic layer; and the conductive catalytic layer is loaded on the hydrophobic membrane to form the conductive catalytic hydrophobic membrane.

[0007] According to an embodiment of the present application, in the conductive catalytic hydrophobic membrane, the material of the conductive layer comprises a material with a conductive function; the material of the catalytic layer comprises a metal material with a catalytic hydrogen evolution function; and the material of the hydrophobic membrane comprises a high polymer material with a support layer.

[0008] According to an embodiment of the present application, the material with electrically conductive function in the conductive catalytic hydrophobic membrane includes: carbon material or stainless steel grid material, the carbon material includes carbon felt, carbon paper or carbon cloth; the metal material with catalytic hydrogen evolution function includes: nickel, iron, cobalt, copper, nickel-based alloy, iron-based alloy, cobalt-based alloy or copper-based alloy;

[0009] The polymer material with the support layer includes: polytetrafluoroethylene or polyvinylidene fluoride.

[0010] According to another aspect of the present application, a preparation method of a conductive catalytic hydrophobic membrane is provided, including:

[0011] loading the metal material with catalytic hydrogen evolution function on the conductive layer to form a conductive catalytic layer;

[0012] loading the conductive catalytic layer on the hydrophobic membrane to form a conductive catalytic hydrophobic membrane;

[0013] wherein, loading the metal material with catalytic hydrogen evolution function on the conductive layer to form a conductive catalytic layer includes:

[0014] preparing a first electroplating solution, wherein the first electroplating solution is prepared by adding a first metal salt as a solute in a solvent;

[0015] loading the metal ion in the first electroplating solution on the material with electrically conductive function by electroplating with the material with electrically conductive function as a cathode and the inert material or the metal material with catalytic hydrogen evolution function as an anode, to form a catalytic layer, wherein the conductive layer and the catalytic layer form a conductive catalytic layer.

[0016] According to an embodiment of the present application, loading the metal material with catalytic hydrogen evolution function on the conductive layer to form a conductive catalytic layer further includes:

[0017] preparing a second electroplating solution, wherein the second electroplating solution is prepared by adding a second metal salt as a solute in a solvent;

[0018] loading the metal ion decomposed from the second metal salt in the second electroplating solution on the material with electrically conductive function by electroplating with the material with electrically conductive function as a cathode and the inert material or the metal material with catalytic hydrogen evolution function as an anode, to form an intermediate catalytic layer;

[0019] adding a third metal salt in the second electroplating solution to obtain a third electroplating solution;

[0020] loading the metal ion of the solute in the third electroplating solution on the intermediate catalytic layer to form a catalytic layer, wherein the conductive layer and the catalytic layer form a conductive catalytic layer.

[0021] According to an embodiment of the present application, loading the conductive catalytic layer on the hydrophobic membrane to form a conductive catalytic hydrophobic membrane further includes:

[0022] The back surface of the conductive layer in the conductive catalytic layer is attached to the hydrophobic membrane to form a conductive catalytic hydrophobic membrane, wherein the back surface of the conductive layer in the conductive catalytic layer is a surface away from the catalytic layer in the conductive catalytic layer.

[0023] According to the embodiment of the present application, the temperature of the first electroplating solution, the second electroplating solution and the third electroplating solution is 20-60℃; the current density of electroplating is 20-30 mA / cm 2 .

[0024] According to the embodiment of the present application, the first metal salt of the solute in the first electroplating solution comprises at least one of iron salt, nickel salt, cobalt salt or copper salt; the metal ion in the metal salt has a catalytic hydrogen evolution effect.

[0025] According to the embodiment of the present application, the second metal salt comprises at least one of nickel salt, iron salt or copper salt; the third metal salt comprises at least one of iron salt, molybdenum salt, tin salt or zinc salt.

[0026] According to another aspect of the present application, there is provided an application of the conductive catalytic hydrophobic membrane, which is used for ammonia-nitrogen wastewater treatment, wherein the conductive catalytic hydrophobic membrane is coupled with an electrochemical process to realize a membrane deamination recovery technology without additional addition of alkaline reagent; the conductive catalytic hydrophobic membrane is obtained according to the embodiment of the present application, or is prepared according to any one of the preparation methods of the embodiment of the present application.

[0027] According to the embodiment of the present application, a conductive catalytic hydrophobic membrane is provided, which couples membrane separation with electrochemistry, without additional addition of alkaline reagent in the membrane deamination system, and in-situ generates OH- at the interface of the conductive catalytic hydrophobic membrane under the action of an applied voltage, reacts with NH4 + in the ammonia-nitrogen wastewater to generate ammonia gas, and recovers ammonia on the water production side of the hydrophobic membrane. In addition, under the action of electrochemistry, the conductive catalytic hydrophobic membrane carries a negative charge, which electrostatically repels the pollutants also carrying a negative charge, thereby improving the anti-pollution ability of the conductive catalytic hydrophobic membrane, electrostatically attracts NH4 + carrying a positive charge, and improves the mass transfer rate of NH4 + , so that the conductive catalytic hydrophobic membrane has the characteristics of strong anti-pollution ability and high ammonia recovery efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0028] The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments of the present application taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 The structural composition of the conductive catalytic hydrophobic membrane according to the embodiment of the present application is shown in the schematic diagram;

[0030] Figure 2 Flow chart for a method of preparing a conductive catalytic hydrophobic membrane according to an embodiment of the present application;

[0031] Figure 3 Schematic diagram of a method of forming a conductive catalytic layer according to an embodiment of the present application;

[0032] Figure 4 Schematic diagram of a method of forming a conductive catalytic layer according to another embodiment of the present application; and

[0033] Figure 5 NH4 + - N concentration-time graph.

[0034] [Explanation of Reference Numerals]

[0035] - conductive catalytic hydrophobic membrane;

[0036] 1 - conductive layer;

[0037] 2 - catalytic layer;

[0038] 3 - conductive catalytic layer;

[0039] 4 - hydrophobic membrane;

[0040] 5 - first electroplating solution;

[0041] 6 - first metal salt;

[0042] 7 - intermediate catalytic layer;

[0043] 8 - second electroplating solution;

[0044] 9 - second metal salt;

[0045] 10 - third electroplating solution; and

[0046] 11 - third metal salt; DETAILED DESCRIPTION

[0047] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It should be understood, however, that the description which follows is merely illustrative and is not intended to limit the scope of the present application. In the following detailed description of embodiments of the present application, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that one or more embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring aspects of the present application.

[0048] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0049] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0050] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). Similarly, when using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0051] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of the present invention. Throughout the accompanying drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding the present invention. Furthermore, the shapes and dimensions of the components in the drawings do not reflect actual size and proportion, but are only schematic representations of the embodiments of the present invention.

[0052] Similarly, it should be understood that, in order to streamline the invention and aid in understanding one or more aspects, various features of the invention may sometimes be grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of the invention. However, this approach should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim.

[0053] In the related art, in the traditional membrane deamination process, alkali reagents such as sodium hydroxide and quicklime need to be added, the alkali reagents react with water to generate hydroxyl ions, the hydroxyl ions react with ammonium ions to generate ammonia, and the ammonia is recovered by penetrating the traditional hydrophobic membrane under the driving of the vapor pressure. In the traditional process, alkali reagents such as sodium hydroxide and quicklime need to be added, which will bring additional reagent cost, and the added alkali reagents are easy to cause membrane fouling, membrane wetting and other phenomena, which affect the ammonia recovery effect and the service life of the membrane.

[0054] Therefore, the present application provides a conductive catalytic hydrophobic membrane, which can generate hydroxyl ions in situ at the interface of the conductive catalytic hydrophobic membrane under the action of an applied voltage, react with ammonium ions in ammonia-nitrogen wastewater to generate ammonia, and recover ammonia by penetrating the conductive catalytic hydrophobic membrane, so as to realize ammonia recovery without adding alkali reagents, and improve the membrane anti-pollution ability and the ammonia recovery effect.

[0055] According to an embodiment of the present application, a conductive catalytic hydrophobic membrane is provided, which comprises: a conductive layer, a catalytic layer and a hydrophobic membrane, wherein the catalytic layer is loaded on the conductive layer to form a conductive catalytic layer; and the conductive catalytic layer is loaded on the hydrophobic membrane to form a conductive catalytic hydrophobic membrane.

[0056] Figure 1 The structure of the conductive catalytic hydrophobic membrane according to the embodiment of the present application is schematically shown.

[0057] As shown in Figure 1 , the conductive catalytic hydrophobic membrane can comprise: a conductive layer 1, a catalytic layer 2 and a hydrophobic membrane 4. The catalytic layer 2 is loaded on the conductive layer 1 to form a conductive catalytic layer 3 together with the conductive layer 1. The hydrophobic membrane 4 can load the conductive catalytic layer 3 on the hydrophobic membrane 4 to form a conductive catalytic hydrophobic membrane.

[0058] In this embodiment, under the action of an applied voltage, water on the surface of the conductive layer 1 is electrolyzed by the voltage, and the catalytic layer 2 plays a role of catalyzing hydrogen evolution, so that water catalyzes hydrogen evolution at a lower current density, thereby generating a large amount of OH - on the interface of the conductive catalytic hydrophobic membrane. On the one hand, OH - adsorbs NH4 + in ammonia-nitrogen wastewater, and reacts with NH4 + to form ammonia, and ammonia molecules are separated by penetrating the hydrophobic membrane 4 under the driving of the vapor pressure, and react with water on the other side of the hydrophobic membrane 4 to generate ammonia water, thereby realizing ammonia recovery and completing the treatment of ammonia-nitrogen wastewater. On the other hand, OH- makes the surface of the conductive catalytic hydrophobic membrane material carry a negative charge, repels the negatively charged pollutants, and thus reduces the occurrence of membrane pollution.

[0059] It should be noted that Figure 1The shown structure is only an example of the structural composition of the embodiment of the present application, to help the skilled in the art understand the technical content of the present application, but does not mean that the conductive catalytic hydrophobic membrane and its composition of the present application is limited to Figure 1 The shape shown can be any shape that can meet the ammonia-nitrogen waste liquid treatment, such as a circle, an ellipse, an irregular figure, etc., according to actual needs.

[0060] It should be understood that Figure 1 The number of conductive layers, catalytic layers and hydrophobic membranes in the above-mentioned embodiment is only illustrative, and any number of conductive layers, catalytic layers and hydrophobic membranes can be provided according to actual needs.

[0061] According to the embodiment of the present application, the conductive catalytic hydrophobic membrane can couple membrane separation with an electrochemical process, without the need to add an alkaline agent in the membrane deamination system, so that the system generates OH - in situ at the interface of the conductive catalytic hydrophobic membrane under the action of an applied voltage, reacts with NH4 + in the ammonia-nitrogen waste liquid to generate ammonia gas, and the ammonia gas molecules pass through the hydrophobic membrane 4 to react with water on the other side of the hydrophobic membrane 4 to generate ammonia water, thereby realizing ammonia recovery. In addition, under the action of electrochemistry, the conductive catalytic hydrophobic membrane carries a negative charge, which will electrostatically repel the pollutants also carrying a negative charge, thereby improving the anti-pollution ability of the conductive catalytic hydrophobic membrane. Electrostatic attraction occurs between the conductive catalytic hydrophobic membrane and NH4 + carrying a positive charge, thereby improving the mass transfer rate of NH4 + and realizing efficient and energy-saving removal and recovery of ammonia-nitrogen in wastewater.

[0062] According to the embodiment of the present application, the material of the conductive layer 1 of the conductive catalytic hydrophobic membrane can include a material having a conductive function; the material of the catalytic layer 2 includes a metal material having a catalytic hydrogen evolution function; and the material of the hydrophobic membrane 4 includes a high polymer material with a support layer.

[0063] According to the embodiment of the present application, in the conductive catalytic hydrophobic membrane, the material having a conductive function can also include a carbon material or a stainless steel grid material, wherein the carbon material can include but is not limited to carbon felt, carbon paper or carbon cloth, etc.

[0064] In the embodiment of the present application, the carbon material or the stainless steel grid material is used as the conductive functional material to realize good conduction of current, and has a series of excellent properties such as high temperature resistance, corrosion resistance, fatigue resistance, creep resistance, etc.

[0065] According to the embodiment of the present application, the metal material having a catalytic hydrogen evolution function can also include nickel (Ni), iron (Fe), tin (Sn), zinc (Zn), nickel-molybdenum alloy (Ni-Mo), nickel-tin alloy (Ni-Sn) or iron-molybdenum alloy (Fe-Mo), etc.

[0066] In the process of combining membrane separation technology and electrochemical technology, it is found that the efficiency of recovering ammonia is closely related to the rate of hydrogen evolution to produce hydroxyl radical. If the hydrogen evolution cathode material in traditional industrial production (such as soft steel, etc.) is used, its stability will gradually deteriorate in the process of long-term electrolysis in a high-temperature strong alkali environment. The single noble metal of platinum group (such as Ru, Rh, Pd, Ir, Pt, etc.) with strong stability and high catalytic hydrogen evolution activity cannot be applied on a large scale due to high cost.

[0067] According to the embodiment of the present application, the metal such as nickel and / or nickel-based alloy can be used as the catalytic hydrogen evolution material of the catalytic layer, which reduces the preparation cost, and enables the conductive catalytic hydrophobic membrane to have the acid and alkali resistance while maintaining good catalytic hydrogen evolution performance.

[0068] According to the embodiment of the present application, the high polymer material with a support layer further includes polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) and the like.

[0069] According to the embodiment of the present application, the PTFE or PVDF with a support layer is used to prepare the conductive catalytic hydrophobic membrane, which is flexible and wear-resistant, and has excellent chemical corrosion resistance and oxidation resistance. Due to the high lubrication and non-adhesion properties of PTFE itself, the adhesion of pollutants on the conductive catalytic hydrophobic membrane is reduced, and the membrane fouling phenomenon is avoided.

[0070] It should be noted that the above-mentioned materials are only used to illustrate the embodiment of the present application, and according to actual needs, the conductive functional material can be any material that can play a conductive role, such as copper, aluminum or conductive paint. Similarly, the selection of the catalytic hydrogen evolution material and the hydrophobic membrane material is not limited, and can be adaptively changed according to the use requirements.

[0071] According to the embodiment of the present application, the present application further proposes a preparation method of the conductive catalytic hydrophobic membrane, which is used to prepare the conductive catalytic hydrophobic membrane as described above.

[0072] Figure 2 A flow chart of the preparation method of the conductive catalytic hydrophobic membrane according to the embodiment of the present application is schematically shown.

[0073] As shown in Figure 2 , the preparation method includes steps S1-S2.

[0074] Step S1, loading the metal material with catalytic hydrogen evolution effect on the conductive layer to form a conductive catalytic layer.

[0075] Step S2, loading the conductive catalytic layer to the hydrophobic membrane to form a conductive catalytic hydrophobic membrane.

[0076] The process of loading a metal material with catalytic hydrogen evolution activity onto a conductive layer to form a conductive catalytic layer may include steps S101-S102.

[0077] Step S101: Prepare a first electroplating solution, wherein the first electroplating solution is prepared by adding a first metal salt as a solute to a solvent.

[0078] Step S102: Using a conductive material as the cathode and an inert material or a metal material with catalytic hydrogen evolution activity as the anode, metal ions from the first electroplating solution are loaded onto the conductive material by electroplating to form a catalytic layer. The conductive layer and the catalytic layer form a conductive catalytic layer. Figure 3 This illustration shows the method for forming a conductive catalyst layer.

[0079] For example, Figure 3 The schematic diagram illustrates a process flow diagram of a method for forming a conductive catalyst layer according to an embodiment of the present invention.

[0080] Combination Figure 3 As shown, the conductive catalyst layer of the present invention can be formed by electroplating, loading a metal material with catalytic hydrogen evolution activity onto the conductive layer 1 to form the catalyst layer 2, and the conductive layer 1 and the catalyst layer 2 together form the conductive catalyst layer 3.

[0081] The first electroplating solution 5 is prepared by adding a first metal salt 6 (solute) to a solvent. The solvent of the first electroplating solution 5 can be water, or an ionic liquid prepared by mixing one of fatty acids, citric acid, or malonic acid with choline chloride, or an ionic liquid prepared by mixing one or two of ethylene glycol, glycerol, triethylene glycol, or urea with choline chloride.

[0082] It should be noted that the present invention does not limit the selection of solvents for electroplating solutions. The above-mentioned solvent types are only illustrative examples of embodiments of the present invention. The solvent for electroplating solutions can be any solvent that meets the requirements of dissolving solvent and electroplating.

[0083] In addition, the solute in the first electroplating solution 5 is the first metal salt 6. After the solvent dissolves the first metal salt 6, it forms a corresponding metal cation, which can be a plating metal cation with catalytic hydrogen evolution effect, or other ions that maintain the stability of the cation concentration in the electroplating solution.

[0084] According to an embodiment of the present invention, the first metal salt 6 may include at least one of the following: iron salt, nickel salt, cobalt salt, or copper salt.

[0085] Specifically, in the electroplating process of this invention embodiment, the conductive functional material can be the electrode to be plated (cathode), and the anode material can be an inert material or a metal material with catalytic hydrogen evolution effect.

[0086] According to the embodiment of the present application, when the anode material is an inert material (such as a titanium plate), the metal cations provided by the first metal salt 6 are reduced to form a plating layer (i.e., the catalytic layer 2) on the surface of the conductive functional material (i.e., the conductive layer 1) to be plated.

[0087] It should be noted that the titanium plate mentioned above is only an example, and according to actual needs, the conductive inert material as the anode can be replaced by one or more of titanium mesh, metal platinum strip, graphite strip / piece, carbon fiber cloth, and inert electrode materials, and there is no specific requirement for the shape.

[0088] In the embodiment, the conductive catalytic layer 3 is loaded on the hydrophobic membrane 4 to prepare a conductive catalytic hydrophobic membrane, which can include: adhering the back surface of the conductive layer 1 in the conductive catalytic layer 3 to the hydrophobic membrane 4, including: using hot pressing, hot compressing, glueing, and physical clamping methods to prepare the conductive catalytic hydrophobic membrane. The back surface of the conductive layer in the conductive catalytic layer is the surface away from the catalytic layer in the conductive catalytic layer.

[0089] According to the embodiment of the present application, the conductive catalytic layer 3 is loaded on the hydrophobic membrane 4 to prepare a conductive catalytic hydrophobic membrane, which can also include: mixing the conductive material and the catalytic material in an organic solvent and spraying it on the surface of the membrane material, and also using a non-solvent phase inversion method to load the conductive catalytic layer material on the surface of the membrane.

[0090] In addition, the method of loading the catalytic layer 2 on the conductive layer 1 is not limited to electroplating, and according to actual needs, other methods capable of loading metal materials with catalytic hydrogen evolution function on the conductive layer 1 (such as using hydrothermal reaction loading, etc.) can also be used.

[0091] The embodiment of the present application discloses another method of loading metal materials with catalytic hydrogen evolution function on a conductive layer to form a conductive catalytic layer, which includes steps S201-S204.

[0092] Step S201, preparing a second electroplating solution, wherein the second electroplating solution is prepared by adding a second metal salt as a solute in a solvent.

[0093] Step S202, using a material with conductive function as a cathode, using an inert material or a metal material with catalytic hydrogen evolution function as an anode, and using electroplating to load the metal ions decomposed from the second metal salt in the second electroplating solution on the material with conductive function to form an intermediate catalytic layer.

[0094] Step S203, adding a third metal salt to the second electroplating solution to obtain a third electroplating solution.

[0095] Step S204, loading the metal ions of the solute in the third electroplating solution on the intermediate catalytic layer to form a catalytic layer, wherein the conductive layer and the catalytic layer form a conductive catalytic layer. Figure 4 Another method for forming the conductive catalytic layer is schematically illustrated. Figure 4 A flowchart schematically illustrating a method for forming a conductive catalytic layer according to another embodiment of the present application is shown.

[0096] Embodiments of the present application adopt a "two-step electroplating" method. Figure 4 As shown, the second electroplating solution 8 is prepared by adding a second metal salt 9 (solute) in a solvent. In the first step of electroplating, the second metal salt 9 is decomposed to form metal cations to be plated, the conductive functional material (i.e., the conductive layer 1) is the cathode, and the metal material with catalytic hydrogen evolution function is the anode. Under the electrolysis, the metal cations after the decomposition of the second metal salt 9 are deposited on the surface of the conductive layer 1 to form a metal plating layer (i.e., the intermediate catalytic layer 7).

[0097] After the first step of electroplating, the concentration of the metal cations in the second electroplating solution 8 is reduced. At this time, a third metal salt 11 is added to the second electroplating solution 8 to obtain a third electroplating solution 10. The third metal salt 11 is decomposed in a solvent to form another metal cation to be plated, and another metal plating layer is formed through the second step of electroplating to form a conductive catalytic layer 3 together with the intermediate catalytic layer 7. In the second step of electroplating, the cathode is the combination of the intermediate catalytic layer 7 and the conductive layer 1, and the anode still uses the material in the first step of electroplating.

[0098] In some embodiments of the present application, the second metal salt 9 and the third metal salt 11 are both single metal salts. The metal cations after the decomposition of the second metal salt 9 are deposited on the conductive layer 1 to form the intermediate catalytic layer 7, which is a metal plating layer corresponding to the second metal salt 9. The third metal salt 11 forms another metal plating layer, which can be a metal plating layer corresponding to the second metal salt 9 and the third metal salt 11.

[0099] When the metal material with catalytic hydrogen evolution function is used as the anode, the anode material generates corresponding metal cations through electrolysis. The metal cations are deposited on the conductive layer 1 together with the metal cations corresponding to the second metal salt 9 to form the intermediate catalytic layer 7, and together with the metal cations corresponding to the second metal salt 9 and the third metal salt 11 to form another alloy plating layer, i.e., to realize the synthesis of the conductive layer to form the conductive catalytic layer 3.

[0100] It should be understood that the present application does not limit the second metal salt 9 and the third metal salt 11 to single metal salts. The above description is only an example of the intermediate catalytic layer 7 and the conductive catalytic layer 3 formed by "two-step electroplating", and the metal salt in the electroplating solution can correspond to one or more metals.

[0101] The second metal salt 9 in the second electroplating solution 8 is different from the first metal salt 6, and the metal cation formed by the decomposition of the second metal salt 9 also has the characteristic of easy deposition, so as to ensure that the to-be-plated metal of the intermediate catalytic layer 7 has the catalytic hydrogen evolution characteristic and is well combined with the conductive layer 1, thereby avoiding the peeling phenomenon of the catalytic layer 3.

[0102] Similarly, in the third electroplating solution 10, the third metal salt 11 is different from the second metal salt 9, and the corresponding metal of the third metal salt 11 has a more excellent catalytic hydrogen evolution effect, and the metal cation formed by the decomposition of the third metal salt 11 forms another metal plating layer, so as to improve the OH- production rate of the prepared conductive catalytic hydrophobic membrane.

[0103] According to the embodiment of the present application, before electroplating the conductive layer 1, the corresponding conductive functional material is pretreated, including but not limited to ethanol cleaning and the like, so as to improve the conductivity of the conductive functional material and realize good combination with the plating layer.

[0104] According to the embodiment of the present application, the conductive catalytic layer 3 is loaded on the hydrophobic membrane 4 to form a conductive catalytic hydrophobic membrane, including:

[0105] The back surface of the conductive layer 1 in the conductive catalytic layer 3 is attached to the hydrophobic membrane 4 to form a conductive catalytic hydrophobic membrane, wherein the back surface of the conductive layer 1 in the conductive catalytic layer 3 is the surface away from the catalytic layer 2 in the conductive catalytic layer 3.

[0106] In the embodiment of the present application, the temperature (i.e. the working temperature of the electroplating tank) of the first electroplating solution, the second electroplating solution and the third electroplating solution is set to 20-60℃, which is beneficial to improve the catalytic hydrogen evolution effect of the conductive catalytic hydrophobic membrane. The current density of the electroplating process is 20-100 mA / cm 2 , so as to avoid the decomposition of the solvent of the electroplating solution to produce gas, and make the prepared conductive catalytic layer 7 smooth and flat, so as to ensure the catalytic hydrogen evolution activity of the prepared conductive catalytic hydrophobic membrane.

[0107] According to the embodiment of the present application, the electroplating working temperature of the first electroplating solution, the second electroplating solution and the third electroplating solution can be 20℃, 30℃, 40℃, 50℃ or 60℃; and the current density can be 20 mA / cm 2 , 40 mA / cm 2 , 60 mA / cm 2 , 80 mA / cm 2 or 100 mA / cm 2 .

[0108] According to the embodiment of the present application, if the electroplating working temperature is too high or too low, the electroplating layer (i.e. the conductive catalytic layer 7) is prone to fall off. Similarly, too high current density will cause the decomposition of the solvent of the electroplating solution to produce gas, which indirectly reduces the catalytic hydrogen evolution activity of the prepared conductive catalytic hydrophobic membrane.

[0109] According to the embodiment of the present application, the first metal salt 6 of the solute in the first electroplating solution 5 comprises at least one of the following: a nickel salt, an iron salt, a molybdenum salt or a zinc salt, and the metal ion in the metal salt has a catalytic hydrogen evolution effect.

[0110] In an exemplary embodiment, the first metal salt 6 can be a single metal salt (such as a nickel salt), and the catalytic layer 2 formed by electroplating is a single metal plating layer (such as a nickel metal plating layer). In another embodiment, the first metal salt 6 is a plurality of metal salts (such as a nickel salt and a molybdenum salt), and the catalytic layer 2 formed by electroplating is an alloy plating layer (such as a nickel-molybdenum alloy plating layer).

[0111] The embodiment of the present application uses one or more metal salts for electroplating, so that the obtained metal plating layer has good catalytic hydrogen evolution activity, indirectly improves the mass transfer rate of NH4 + , and further realizes efficient treatment of ammonia-nitrogen-containing waste liquid.

[0112] It should be noted that the above-mentioned metal salt types are only examples of the embodiments of the present application, and other catalytic hydrogen evolution metal corresponding metal salts can also be selected according to actual needs.

[0113] According to the embodiment of the present application, the second metal salt 9 can comprise at least one of the following: a nickel salt, an iron salt or a copper salt; and the third metal salt 11 can comprise at least one of the following: an iron salt, a molybdenum salt or a zinc salt.

[0114] In an exemplary embodiment, carbon felt is used as the conductive functional material (cathode), a nickel metal rod is used as the anode material, the second metal salt can be a nickel salt, a nickel metal plating layer is loaded on the carbon felt through the electroplating process to form a nickel-carbon felt; and a molybdenum salt is added to the electroplating solution, a nickel-molybdenum alloy plating layer is loaded on the nickel-carbon felt through the electroplating process, and finally a conductive catalytic layer 3 is formed.

[0115] In the embodiment of the present application, the metal plating layer corresponding to the second metal salt 9 is formed on the surface of the conductive functional material, which has the catalytic hydrogen evolution characteristics and is well combined with the conductive layer 1, avoiding the peeling phenomenon of the catalytic layer 3. The corresponding metal of the third metal salt 11 has a more excellent catalytic hydrogen evolution effect, which improves the OH - production rate of the conductive catalytic hydrophobic membrane, indirectly improves the mass transfer rate of NH4 + , and further realizes efficient treatment of ammonia-nitrogen-containing waste liquid.

[0116] According to the embodiment of the present application, the present application also discloses an application of a conductive catalytic hydrophobic membrane for ammonia-nitrogen wastewater treatment, wherein the conductive catalytic hydrophobic membrane is combined with an electrochemical process to realize ammonia recovery in the membrane separation process; the conductive catalytic hydrophobic membrane is obtained according to the embodiment of the present application, or is prepared according to any one of the preparation methods of the embodiment of the present application.

[0117] In the conductive catalytic hydrophobic membrane of this invention, the conductive catalytic hydrophobic membrane electrode serves as the cathode and is connected to the negative terminal of a DC power supply, while the conductive inert electrode material serves as the anode and is connected to the positive terminal of the DC power supply. The electrodes are connected using wires, and the operating voltage range is 0–30V. The conductive layer 1 conducts current and provides an applied voltage. The catalytic layer 2 and the conductive layer 1 together form the conductive catalytic layer 3, which electrolyzes water to produce hydrogen, generating OH- on its surface. - To adsorb NH4 + It reacts with the ammonia to form ammonia gas. Using a cross-flow filtration method, the ammonia gas permeates through the hydrophobic membrane 4 under the push of vapor pressure. The ammonia gas that permeates through the membrane is collected by the recovery liquid, thus completing the removal and recovery of ammonia from the ammonia nitrogen wastewater.

[0118] Figure 5 This illustration schematically demonstrates the application of a conductive catalytic hydrophobic membrane according to an embodiment of the present invention in the recovery of NH4 from ammonia nitrogen wastewater treatment. + -N concentration-time plot.

[0119] like Figure 5 As shown, as the treatment time increased from 0 min to 480 min, hydrogen evolution reaction occurred at the cathode, and OH groups were generated in the region near the cathode. - As ion concentration increases, OH - NH4 in ammonia nitrogen wastewater + The reaction produces ammonia gas, which is absorbed by the recovery liquid through the conductive catalytic hydrophobic membrane. The NH4+ in the recovery liquid... + The concentration of -N increased linearly from 0 mg / L to 21.4 mg / L, ultimately achieving efficient separation and recovery of ammonia nitrogen from wastewater.

[0120] The conductive catalytic hydrophobic membrane provided by this invention is applied to the treatment of ammonia nitrogen wastewater, coupling membrane separation with an electrochemical process. This eliminates the need for additional alkaline reagents in the membrane deammoniation system, allowing the system to generate OH- in situ at the conductive catalytic hydrophobic membrane interface under the influence of an applied voltage. - With NH4 in ammonia nitrogen waste liquid + The reaction generates ammonia gas, which is then recovered through the hydrophobic membrane 4. Furthermore, under electrochemical action, the conductive catalytic hydrophobic membrane becomes negatively charged, causing electrostatic repulsion with similarly negatively charged pollutants. This enhances the antifouling ability of the conductive catalytic hydrophobic membrane, allowing it to react with positively charged NH4+. + Electrostatic attraction occurs, increasing NH4+. + The high mass transfer rate enables the conductive catalytic hydrophobic membrane to exhibit strong anti-fouling capabilities and high ammonia recovery efficiency.

[0121] It should be noted that the connection mode of the wire, and the range of the working voltage in the above embodiments are only examples, and can be changed as needed. Similarly, the cross-flow filtration method is only used to illustrate the processing process, and other filtration forms including dead-end filtration (only as an example) can also be used.

[0122] According to the embodiment of the present application, in the application process of the conductive catalytic hydrophobic membrane, the anode conductive material can be composed of one or two of titanium, platinum, stainless steel, graphite sheet or carbon fiber cloth inert electrode material, but is not limited to the above materials.

[0123] According to the embodiment of the present application, in the application process of the conductive catalytic hydrophobic membrane, the ammonia recovery can be achieved by vacuum or air sweeping to recover ammonia, or by flowing sulfuric acid, water and other solutions good for ammonia solubility over the membrane surface to recover ammonia.

[0124] The preparation method and application of the conductive catalytic hydrophobic membrane of the present application are further described and illustrated by specific examples. However, it should be noted that the specific examples described below are only used as examples, and the protection scope of the present application is not limited thereto.

[0125] The chemicals and raw materials used in the following examples are commercially available or obtained by known preparation methods.

[0126] Example 1

[0127] The preparation method of the conductive catalytic hydrophobic membrane Ni-Mo / carbon felt-PTFE of the present embodiment is implemented according to the following steps:

[0128] I. Preparation of the second electroplating solution: mix choline chloride, urea and ethylene glycol raw materials in a closed container at the same molar ratio, then place it in a water bath device, control the temperature at 85°C. Stir the mixed solution until the three are completely dissolved, and finally form a colorless transparent viscous ionic liquid.

[0129] Take a certain amount of ionic liquid and add nickel sulfate, nickel chloride, boric acid and sodium dodecyl benzene sulfonate to it in sequence to prepare the electroplating solution.

[0130] II. Forming an intermediate catalytic layer: use cast nickel as anode and carbon felt as cathode, keep the solution pH at 3-4, control the plating solution temperature at 20-60°C, and electroplate Ni on the carbon felt to form Ni-carbon felt.

[0131] III. Preparation of the third electroplating solution: take a certain amount of ionic liquid and add nickel sulfate, sodium citrate and ammonium molybdate to it in sequence to prepare the electroplating solution.

[0132] Four, forming conductive catalytic layer: with titanium mesh as anode, Ni-carbon felt as cathode, controlling plating solution temperature as 20-60℃, plating Ni-Mo on Ni-carbon felt to form conductive catalytic material.

[0133] Five, preparing conductive catalytic hydrophobic membrane: under 0.2-0.3Mpa pressure and 120-180℃ temperature, pressing the prepared conductive catalytic material to PTFE membrane surface to prepare conductive catalytic hydrophobic membrane material Ni-Mo / carbon felt-PTFE.

[0134] Example 2

[0135] The application of conductive catalytic hydrophobic membrane Ni-Mo / carbon felt-PTFE of the embodiment is implemented according to the following process:

[0136] One, connecting wastewater treatment component: conductive hydrophobic membrane experiment is carried out in self-made membrane component, conductive catalytic hydrophobic membrane as working cathode is connected with direct current power negative pole through wire, titanium mesh as working anode is connected with direct current power negative pole through wire, and the two electrodes are placed in parallel.

[0137] Two, carrying out wastewater treatment: adopting cross-flow filtration, raw water is wastewater with ammonia nitrogen concentration of 300mg / L, which enters the component at 300ml / min, and 2% volume fraction dilute sulfuric acid as recovery liquid passes through the component at 60ml / min. 40A / m 2 of current is passed to the electrode to carry out ammonia nitrogen recovery.

[0138] Those skilled in the art can understand that the features described in various embodiments and / or claims of the present application can be combined and / or integrated in various ways, even if such combinations or integrations are not explicitly described in the present application. In particular, the features described in various embodiments and / or claims of the present application can be combined and / or integrated in various ways without departing from the spirit and teachings of the present application. All these combinations and / or integrations fall within the scope of the present application.

[0139] The embodiments of the present application are described above. However, these embodiments are only for illustrative purposes, and are not intended to limit the scope of the present application. Although each embodiment is described above separately, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present application is defined by the appended claims and their equivalents. Without departing from the scope of the present application, those skilled in the art can make various substitutions and modifications, which should all fall within the scope of the present application.

Claims

1. Use of an electrically conductive catalytic hydrophobic membrane for ammonia nitrogen wastewater treatment, said electrically conductive catalytic hydrophobic membrane being combined with an electrochemical process to enable the recovery of ammonia during a membrane separation process, said electrically conductive catalytic hydrophobic membrane comprising: A conductive layer, a catalytic layer and a hydrophobic membrane, wherein, The catalytic layer is loaded on the conductive layer to form a conductive catalytic layer, and the material of the catalytic layer comprises a metal material having a catalytic hydrogen evolution effect; the hydrophobic membrane, the conductive catalytic layer is loaded onto the hydrophobic membrane to form a conductive catalytic hydrophobic membrane, the conductive catalytic layer is used to catalyze the hydrogen evolution reaction in the electrochemical process, so that the interface of the conductive catalytic hydrophobic membrane generates OH - .

2. The application of the conductive catalytic hydrophobic membrane for ammonia-nitrogen wastewater treatment according to claim 1, wherein, The material of the conductive layer comprises a material having a conductive function; The material of the hydrophobic membrane comprises a high polymer material with a supporting layer.

3. The application of the conductive catalytic hydrophobic membrane for ammonia-nitrogen wastewater treatment according to claim 2, wherein, The material having a conductive function comprises a carbon material or a stainless steel grid material, and the carbon material comprises carbon felt, carbon paper or carbon cloth; The metal material having a catalytic hydrogen evolution effect comprises nickel, iron, cobalt, copper, nickel-based alloy, iron-based alloy, cobalt-based alloy or copper-based alloy; The high polymer material with a supporting layer comprises polytetrafluoroethylene or polyvinylidene fluoride.

4. Use of the conductive catalytic hydrophobic membrane according to any one of claims 1 to 3 for the treatment of ammonia-nitrogen wastewater, wherein, A preparation method of the conductive catalytic hydrophobic membrane, comprising: loading a metal material having a catalytic hydrogen evolution effect on the conductive layer to form a conductive catalytic layer; loading the conductive catalytic layer on a hydrophobic membrane to form a conductive catalytic hydrophobic membrane; The loading of the metal material having a catalytic hydrogen evolution effect on the conductive layer to form a conductive catalytic layer comprises: preparing a first electroplating solution, wherein the first electroplating solution is prepared by adding a first metal salt as a solute in a solvent; loading metal ions in the first electroplating solution on a material having a conductive function as a cathode and an inert material or a metal material having a catalytic hydrogen evolution effect as an anode by electroplating to form a catalytic layer, wherein the conductive layer and the catalytic layer form a conductive catalytic layer.

5. Use of the electrically conductive catalytic hydrophobic membrane according to claim 4 for ammonia-nitrogen wastewater treatment, wherein, The loading of the metal material having a catalytic hydrogen evolution effect on the conductive layer to form a conductive catalytic layer comprises: preparing a second electroplating solution, wherein the second electroplating solution is prepared by adding a second metal salt as a solute in the solvent; loading metal ions decomposed from the second metal salt in the second electroplating solution on the material having a conductive function as a cathode and an inert material or a metal material having a catalytic hydrogen evolution effect as an anode by the electroplating to form an intermediate catalytic layer; adding a third metal salt in the second electroplating solution to obtain a third electroplating solution; loading metal ions of the solute in the third electroplating solution on the intermediate catalytic layer to form a catalytic layer, wherein the conductive layer and the catalytic layer form a conductive catalytic layer.

6. Use of the electrically conductive catalytic hydrophobic membrane according to claim 4 for ammonia-nitrogen wastewater treatment, wherein, The loading of the conductive catalytic layer on a hydrophobic membrane to form a conductive catalytic hydrophobic membrane comprises: attaching the back surface of the conductive layer in the conductive catalytic layer to the hydrophobic membrane to form the conductive catalytic hydrophobic membrane, wherein the back surface of the conductive layer in the conductive catalytic layer is a surface away from the catalytic layer in the conductive catalytic layer.

7. Use of the electrically conductive catalytic hydrophobic membrane according to claim 5 for ammonia-nitrogen wastewater treatment, wherein, The temperature of the first electroplating solution, the second electroplating solution and the third electroplating solution is 20-60℃; the current density of the electroplating is 20-100 mA / cm 2 .

8. Use of the electrically conductive catalytic hydrophobic membrane according to claim 4 for ammonia-nitrogen wastewater treatment, wherein, The first metal salt of the solute in the first electroplating solution comprises at least one of a nickel salt, an iron salt, a cobalt salt or a copper salt, and the metal ions in the metal salt have a catalytic hydrogen evolution effect.

9. Use of the electrically conductive catalytic hydrophobic membrane according to claim 5 for ammonia-nitrogen wastewater treatment, wherein, The second metal salt includes at least one of a nickel salt, an iron salt, and a copper salt; and the third metal salt includes at least one of an iron salt, a molybdenum salt, a tin salt, or a zinc salt.

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