A device and method for recycling heavy metals in industrial wastewater

Abstract

The application provides a device and method for recycling heavy metals in industrial wastewater, which comprises a hydrogen sulfide gas supply unit, a heavy metal recycling unit and a catalyst production unit; the heavy metal recycling unit comprises a first shell, which is provided with a water inlet, a water outlet, an air inlet, an exhaust port and a first material outlet, and is provided with a gas distribution assembly and a stripping assembly in the first shell; the gas distribution assembly comprises a hydrophobic hollow fiber membrane, and the hydrogen sulfide gas supply unit is communicated with the hollow inner cavity of the hydrophobic hollow fiber membrane through the air inlet of the first shell; the catalyst production unit comprises a second shell, which is provided with a second material inlet, a third material inlet and a catalyst outlet, and is provided with a Joule heat flash evaporation device in the second shell; and the first material outlet is communicated with the second material inlet. The device can recycle heavy metals in industrial wastewater to regenerate a composite catalyst with economic prospects, and realizes the resource utilization of industrial wastewater.

Description

Technical Field

[0001] This invention relates to the field of water treatment, and more particularly to an apparatus and method for recycling heavy metals from industrial wastewater. Background Technology

[0002] Heavy metal industrial wastewater mainly comes from industries such as mining, non-ferrous metal smelting and processing, electroplating, and pesticides. It mainly contains heavy metals such as copper (Cu), zinc (Zn), nickel (Ni), cadmium (Cd), and cobalt (Co). How to effectively treat heavy metal industrial wastewater and recycle heavy metals is a key research focus and challenge in industrial wastewater treatment and resource utilization.

[0003] Conventional methods for treating heavy metal industrial wastewater mainly involve chemical precipitation, which adjusts the solution pH to cause heavy metal ions to form hydroxide precipitates, or physical separation methods such as ion exchange resins, adsorbents, and reverse osmosis. Traditional chemical precipitation methods require large amounts of alkaline substances to adjust the pH and also generate significant amounts of hazardous precipitated waste; the pH of the post-reaction solution also needs to be adjusted to neutral. Physical separation methods can transfer target pollutants from water to resins or adsorbents, but the high cost and low regeneration efficiency of these materials limit their application in high-concentration heavy metal industrial wastewater. Furthermore, these existing methods only achieve the separation of heavy metals from industrial wastewater and do not enable the resource utilization of these heavy metals. Summary of the Invention

[0004] This invention provides a device for recycling heavy metals in industrial wastewater. The device can recover heavy metals from industrial wastewater and use the recovered heavy metal ions to regenerate economically promising graphene catalysts loaded with metal sulfides, thereby achieving efficient resource utilization of industrial wastewater.

[0005] The present invention also provides a method for recycling heavy metals in industrial wastewater using the above-mentioned device. This method is simple and easy to implement, and can achieve the recycling and reuse of heavy metals in industrial wastewater with the help of the above-mentioned device.

[0006] On the one hand, the present invention provides an apparatus for recycling heavy metals in industrial wastewater, including a heavy metal recovery unit and a catalyst production unit;

[0007] The heavy metal recovery unit includes a first housing, which has a water inlet, a water outlet, a hydrogen sulfide inlet, an exhaust outlet, and a first material outlet. The first housing contains an air distribution assembly and a stripping assembly. The air distribution assembly includes a hydrophobic hollow fiber membrane, and the hydrogen sulfide inlet communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane.

[0008] The catalyst production unit includes a second shell, which is provided with a second material inlet, a third material inlet and a catalyst outlet. The second shell is equipped with a Joule heat flash evaporator.

[0009] The first material outlet is connected to the second material inlet.

[0010] In an optional embodiment, the system further includes a water purification unit and an oxidant supply unit. The water purification unit includes a third housing, which has a fourth material inlet, a fifth material inlet, an industrial wastewater inlet, and a purified water outlet. A stirring device is provided inside the third housing. The catalyst outlet on the second housing is connected to the fourth material inlet, and the fifth material inlet is connected to the oxidant outlet of the oxidant supply unit.

[0011] And / or, the purified water outlet and the water inlet on the first housing are connected by a detachable pipe.

[0012] In an optional embodiment, the system further includes a separation unit comprising a fourth housing having a liquid inlet, a liquid outlet, and a sludge outlet; a separation membrane is provided within the separation chamber; the liquid inlet and liquid outlet are located on opposite sides of the separation membrane; the sludge outlet and liquid inlet are located on the same side of the separation membrane; the liquid inlet is connected to the outlet of the first housing; and the liquid outlet is connected to the industrial wastewater inlet of the third housing.

[0013] In an optional embodiment, the stripping assembly includes a drive member and a stripping member electrically connected, the drive member driving the stripping member to strip solids attached to the surface of the hydrophobic hollow fiber membrane and conveying the stripped solids to the catalyst outlet.

[0014] In an optional embodiment, the first housing is further provided with at least two liquid guide plates, located on both sides of the gas distribution assembly.

[0015] In an optional embodiment, the gas distribution assembly includes a membrane support and a hydrophobic hollow fiber membrane fixed by the membrane support. The membrane support includes a cavity that communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane. The hydrogen sulfide inlet communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane through the cavity of the membrane support.

[0016] Furthermore, the present invention provides a method for recovering heavy metals from industrial wastewater using the above-mentioned device, comprising the following steps:

[0017] 1) Hydrogen sulfide gas is introduced into the cavity of the hydrophobic hollow fiber membrane through the hydrogen sulfide gas supply unit;

[0018] 2) The industrial wastewater to be treated enters the heavy metal ion recovery unit through the inlet of the first shell and comes into full contact with the surface of the hydrophobic hollow fiber membrane to react and generate metal sulfides.

[0019] 3) The stripping component strips the metal sulfide from the surface of the hydrophobic hollow fiber membrane and sends it to the catalyst production unit in sequence through the first material outlet and the second material inlet. The carbon material is sent to the catalyst production unit through the third material inlet. The metal sulfide and carbon material are mixed in the catalyst production unit and heat-treated by the Joule heat flash evaporation equipment to obtain the graphene catalyst loaded with metal sulfide.

[0020] In an optional embodiment, the method further includes a step of purifying industrial wastewater discharged from the outlet of the first housing by contacting a mixture of a graphene catalyst and an oxidant containing the loaded metal sulfide.

[0021] Preferably, the mass ratio of the graphene catalyst loaded with metal sulfides to the oxidant is 1 to 50:1.

[0022] In an optional embodiment, the mass ratio of the metal sulfide precipitate to the carbon material is 1:1 to 10.

[0023] In an optional embodiment, the heat treatment includes the following process: starting from room temperature, the temperature is raised to 300-1500°C after 3-5 seconds, held for 1-60 seconds, and then raised again to 500-2000°C after 3-5 seconds, held for 1-60 seconds.

[0024] The device of this invention employs a bubble-free aeration method for hydrogen sulfide, causing heavy metal ions in industrial wastewater to precipitate as solid metal sulfides on the membrane surface, reducing the ineffective escape of hydrogen sulfide and improving hydrogen sulfide utilization efficiency. Furthermore, the solid metal sulfide precipitate and carbon materials can be synthesized into a graphene catalyst loaded with metal sulfides via Joule heating flash evaporation, realizing the recovery and reuse of heavy metals in industrial wastewater. Optionally, the aforementioned graphene catalyst loaded with metal sulfides can also be used in downstream processes for catalytic oxidation purification of industrial wastewater, thereby alleviating the increasingly strained water resources and achieving efficient resource utilization of the graphene catalyst loaded with metal sulfides. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] Figure 1 This invention provides a device for recycling heavy metals from industrial wastewater, as a specific embodiment of the present invention.

[0027] In the diagram, 001: Heavy metal recovery unit, 0011: Water inlet, 0012: Water outlet, 0013: Hydrogen sulfide inlet, 0014: Exhaust outlet, 0015: Gas distribution assembly, 0016: First material outlet, 002: Catalyst production unit, 0021: Second material inlet, 0022: Third material inlet, 0023: Catalyst outlet, 0024: Joule heat flash evaporation equipment;

[0028] Figure 2 This is a schematic diagram showing the connection relationship of each unit of a device for recycling heavy metals in industrial wastewater according to a specific embodiment of the present invention.

[0029] In the diagram, 005: hydrogen sulfide gas supply unit, 001: heavy metal recovery unit, 002: catalyst production unit, 003: purification unit, 004: separation unit, and 006: oxidant supply unit.

[0030] Figure 3 This is a schematic diagram of the purification unit and separation unit of a device for recycling heavy metals in industrial wastewater according to a specific embodiment of the present invention.

[0031] In the diagram, 0031: Fourth material inlet, 0032: Fifth material inlet, 0033: Industrial wastewater inlet, 0034: Purified water outlet, 0035: Stirring device, 0041: Liquid inlet, 0042: Liquid outlet, 0043: Sludge outlet, 0045: Separation membrane.

[0032] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of the application will be clearly and completely described below in conjunction with the embodiments of the invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, the terms describing positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0036] In a first aspect, the present invention provides a device for recycling heavy metals from industrial wastewater, combined with... Figure 1 The device is described in detail, including a heavy metal recovery unit 001 and a catalyst production unit 002.

[0037] The heavy metal recovery unit includes a first housing, which has an inlet 0011, an outlet 0012, a hydrogen sulfide inlet 0013, an exhaust outlet 0014, and a first material outlet 0016. The first housing contains an air distribution assembly 0015 and a stripping assembly. The air distribution assembly includes a membrane support and a hydrophobic hollow fiber membrane fixed by the membrane support. The hydrogen sulfide inlet 0013 communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane.

[0038] The catalyst production unit includes a second shell, on which a second material inlet 0021, a third material inlet 0022 and a catalyst outlet 0023 are provided, and a Joule heat flash evaporation device 0024 is provided inside the second shell.

[0039] The first material outlet 0016 is connected to the second material inlet 0021.

[0040] In this invention, a hydrophobic hollow fiber membrane is used to allow hydrogen sulfide gas to contact and react with heavy metal ions in industrial wastewater through bubble-free aeration. The bubble-free aeration method can reduce the ineffective dissipation of hydrogen sulfide and improve the utilization efficiency of hydrogen sulfide. The generated solid metal sulfide precipitate adheres to the surface of the hydrophobic hollow fiber membrane. The solid metal sulfide can be peeled off from the surface of the hydrophobic hollow fiber membrane by a peeling component and transported to the second shell. At the same time, carbon material is transported to the second shell and mixed with the solid metal sulfide. Finally, the carbon material and the solid metal sulfide react through a Joule thermal flash evaporation device to obtain a graphene catalyst loaded with metal sulfides.

[0041] For example, the second housing includes a first conveyor and a second conveyor, wherein the first conveyor is used to accurately convey the materials from the second material inlet 0021 and the third material inlet 0022 into the Joule hot flash evaporator, and the second conveyor is used to send the catalyst out through the catalyst outlet; the first conveyor and the second conveyor can be conveying pipes or conveying robotic arms.

[0042] Preferably, one end of the hollow inner cavity of the hydrophobic hollow fiber membrane is connected to the hydrogen sulfide inlet 0013, and the other end is preferably a closed structure to prevent hydrogen sulfide gas from escaping from the hydrophobic hollow fiber membrane and to save reaction gas.

[0043] It is understood that the aforementioned first and second shells can be configured in any form capable of containing wastewater, such as any shell composed of a cylinder, cube, prism, etc., formed by the top, top surface, and side surfaces. The aforementioned hydrophobic hollow fiber membrane can be of any shape, including but not limited to a curtain, cube, hollow cube, or tree-like structure composed of several fiber membranes. To increase the contact area between the hydrophobic hollow fiber membrane and the wastewater, it is preferable to configure the hydrophobic hollow fiber membrane as a curtain type. Furthermore, based on the volume of the water purification unit, a curtain-type hydrophobic hollow fiber membrane with a large surface area should be designed. For example, the hydrophobic hollow fiber membrane can be composed of six spaced-apart curtain-type hydrophobic polytetrafluoroethylene hydrophobic hollow fiber membranes. When the cross-sectional area of ​​the first shell is 4m²... 2 The effective area of ​​each of the above-mentioned hydrophobic hollow fiber membranes is 3.6 m². 2 The hydrophobic hollow fiber membrane can be made of materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polypropylene (PP), and polyethylene (PE), or a hydrophobically modified ceramic membrane. The outer diameter of the hydrophobic hollow fiber membrane filaments ranges from 0.3 to 8 mm, the inner diameter ranges from 0.15 to 6 mm, the pore size ranges from 0.05 to 0.45 μm, the water contact angle is 90 to 170°, the porosity is 30% to 70%, and the bubble point is 0.5 MPa.

[0044] In one specific embodiment, the system further includes a hydrogen sulfide gas supply unit 005, which includes an air bladder. The air bladder is provided with an air inlet and an air outlet. The air outlet is connected to the hydrogen sulfide gas inlet 0013. After passing through the air bladder, the hydrogen sulfide gas enters the hydrophobic hollow fiber membrane. The air bladder is used to control and buffer the gas pressure inside the membrane. The hydrophobic hollow fiber membrane is preferably a closed-end hydrophobic hollow fiber membrane, which makes full use of the hydrogen sulfide gas while further saving processing resources and processing space. A pressure gauge can be installed on the air bladder to monitor the pressure of the entire gas distribution assembly in real time.

[0045] Preferably, the above-mentioned device further includes a water purification unit 003 and an oxidant supply unit 006, and the connection relationship of each unit can be found in the appendix. Figure 2 See the structural schematic diagram of the water purification unit. Figure 3 It includes a third shell, on which a fourth material inlet 0031, a fifth material inlet 0032, an industrial wastewater inlet 0033, and a purified water outlet 0034 are provided. A stirring device 0035 is provided inside the third shell. The catalyst outlet on the second shell is connected to the fourth material inlet, and the fifth material inlet is connected to the oxidant outlet of the oxidant supply unit.

[0046] When the apparatus of the present invention includes a water purification unit and an oxidant supply unit, industrial wastewater can be catalytically oxidized using a graphene catalyst loaded with metal sulfides to achieve the purification and recovery of industrial wastewater. The industrial wastewater here can be industrial wastewater discharged from the heavy metal recovery unit or untreated industrial wastewater.

[0047] More preferably, the purified water outlet 0034 and the water inlet 0011 on the first housing are connected by a detachable pipe. When the graphene catalyst carrying metal sulfides is used for too long, metal ions are lost, which may cause the catalyst to become deactivated. At this time, the purified water outlet 0034 and the water inlet 0011 on the first housing can be connected by a pipe so that the water containing metal ions flows back into the heavy metal recovery unit 001 for recycling.

[0048] Since industrial wastewater may contain a small amount of impurities that are insoluble in water, in order to prevent these impurities from accumulating in the device for a long time and affecting the use of the device, technicians can regularly clean the solid deposits in the device. Preferably, the industrial wastewater can be filtered to remove impurities before being introduced into the heavy metal recovery unit, or the industrial wastewater can be filtered to remove impurities after passing through the heavy metal recovery unit before being introduced into the purified water outlet 0034.

[0049] In one specific embodiment, the above-mentioned device further includes a separation unit 004, and the connection relationship of each unit can be found in the appendix. Figure 2 See the structural schematic diagram of the separation unit. Figure 3The separation unit includes a fourth housing, which has a liquid inlet 0041, a liquid outlet 0042, and a sludge outlet 0043. A separation membrane 0045 is provided in the separation chamber. The liquid inlet 0041 and the liquid outlet 0042 are located on opposite sides of the separation membrane. The sludge outlet 0043 is located on the same side of the separation membrane as the liquid inlet 0041. The liquid inlet 0041 is connected to the outlet 0012 of the first housing, and the liquid outlet 0041 is connected to the industrial wastewater inlet 0033 of the third housing.

[0050] It is understood that the liquid inlet 0041 and liquid outlet 0042 are located on the left and right sides of the separation membrane, respectively. As to whether they are on the top or bottom of the membrane, the present invention does not make a special limitation. The separation membrane can be a microfiltration membrane, which is used to separate solids and liquids. Even if the solid sludge is retained on the liquid inlet 0041 side, the liquid flows through the separation membrane to the liquid outlet 0042 side and then flows through the liquid outlet 0042 to the water purification unit 003 for wastewater purification.

[0051] For example, the separation membrane described above includes a number of pores with a diameter of 0.05 μm to 1 μm.

[0052] Preferably, the stripping assembly includes a drive member and a stripping member, which are electrically connected. The drive member is used to drive the stripping member to strip the solids attached to the surface of the hydrophobic hollow fiber membrane and to transport the stripped solids to the catalyst outlet.

[0053] For example, the stripping member can move up, down, left, right or vibrate. The driving member includes an electric drive control system and a conveying system. The conveying system includes a collecting member and a conveying member. The electric drive controls the stripping member to strip through an electrical signal and causes the stripped material to fall into the collecting member (the collecting member can be a container for holding objects). The control system controls the conveying member to transport the stripped material in the collecting member to the catalyst outlet.

[0054] Preferably, the gas distribution assembly includes a membrane support and a hydrophobic hollow fiber membrane fixed by the membrane support. The membrane support includes a cavity that communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane. The hydrogen sulfide inlet communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane through the cavity of the membrane support.

[0055] In one specific embodiment, a hollow pipe is provided at any position of the membrane support. The hollow pipe can be part of the support or a separate part. One end of the hollow pipe is sealed, and the other end is connected to the hydrogen sulfide supply unit through the hydrogen sulfide inlet of the first housing. The surface of the hollow pipe includes a plurality of holes, and the hollow cavities of the plurality of hydrophobic hollow fiber membranes that make up the curtain-type hydrophobic hollow fiber membrane correspond to and are connected to these holes.

[0056] The hollow membrane support can be connected to the top or bottom surface of the first housing via a connecting device, or it can be vertically erected inside the first housing by its own supporting force.

[0057] Preferably, the first housing is further provided with at least two liquid guide plates, which are located on both sides of the gas distribution assembly.

[0058] Preferably, the above-mentioned device further includes an exhaust gas recovery unit, which includes a gas inlet and a gas outlet. The exhaust gas recovery unit is equipped with a drying component inside. The gas inlet of the exhaust gas recovery unit is connected to the exhaust port 0014 of the first housing. The gas outlet of the exhaust gas recovery unit is connected to the hydrogen sulfide inlet 0013 of the first housing through a conveying pipe. The conveying pipe is equipped with a one-way valve to control the gas to flow unidirectionally from the recovery unit to the hydrogen sulfide inlet 0013. The drying component is used to dry the exhaust gas.

[0059] Secondly, the present invention provides a method for recovering heavy metals from industrial wastewater using the above-mentioned apparatus, comprising the following steps:

[0060] 1) Hydrogen sulfide gas is introduced into the cavity of the hydrophobic hollow fiber membrane through the hydrogen sulfide gas supply unit;

[0061] 2) The industrial wastewater to be treated enters the heavy metal ion recovery unit through the inlet of the first shell and comes into full contact with the surface of the hydrophobic hollow fiber membrane to react and generate metal sulfides.

[0062] 3) The stripping component strips the metal sulfide from the surface of the hydrophobic hollow fiber membrane and sends it to the catalyst production unit in sequence through the first material outlet and the second material inlet. The carbon material is sent to the catalyst production unit through the third material inlet. The metal sulfide and carbon material are mixed in the catalyst production unit and heat-treated by the Joule heat flash evaporation equipment to obtain the graphene catalyst loaded with metal sulfide.

[0063] The aforementioned carbon materials include, but are not limited to, at least one of the following: carbon black, graphene, carbon nanotubes, biochar, biomass, or liquids containing dissolved carbon-nitrogen ring substances (such as aniline, melamine, polyamide, etc.); wherein, the biochar may be formed by sintering waste crop straw.

[0064] It is understood that the aforementioned hydrogen sulfide gas should be kept dry. As for its flow rate and pressure, technicians can adjust them according to the actual situation; for example, a flow rate of 0.01–12 m³ / s. 3 / h, pressure 0.01~0.5bar;

[0065] Preferably, the above method further includes a step of purifying the industrial wastewater discharged from the outlet of the first housing by contacting a mixture containing the graphene catalyst and oxidant containing the loaded metal sulfide; it is understood that this can be performed using a device including a purification unit 003 and an oxidant supply unit 006.

[0066] Preferably, the mass ratio of the graphene catalyst loaded with metal sulfide to the oxidant is 1 to 50:1.

[0067] The mixing ratio of metal sulfide to carbon material directly affects the proportion of metal sulfide loaded in the catalyst, and thus affects the catalytic activity of the catalyst. Therefore, in order to ensure the purification effect of water, the mass ratio of metal sulfide to carbon material is preferably 1:1 to 10.

[0068] To ensure a more complete reaction, the particle size of the metal sulfide and carbon material is no higher than 5 mm. However, if the particle size of the raw materials is too small, the metal sulfide loading will be easily lost. Therefore, preferably, the particle size of the metal sulfide and carbon material is in the range of 100 μm to 3 mm.

[0069] Preferably, the heat treatment includes the following process: starting from room temperature, the temperature is raised to 300-1500°C after 3-5 seconds, held for 1-60 seconds, and then raised again to 500-2000°C after 3-5 seconds, held for 1-60 seconds. Under these conditions, the metal sulfide precipitate can fully react with the carbon material, thereby generating a graphene catalyst with uniformly supported metal sulfides.

[0070] The present invention will be described in detail below with reference to specific embodiments:

[0071] The hydrophobic hollow fiber membrane is made of polytetrafluoroethylene (PTFE) with the following parameters: pore size of 0.22 μm and porosity of 65%. Biochar is also used.

[0072] Example 1

[0073] This example provides a device for recycling heavy metals from industrial wastewater, combined with... Figure 2 The device includes a hydrogen sulfide gas supply unit 005, a heavy metal recovery unit 001, a catalyst production unit 002, a purification unit 003, a separation unit 004, and an oxidant supply unit 006.

[0074] Combination Figure 1The heavy metal recovery unit 001 includes a first housing, which has an inlet 0011, an outlet 0012, a hydrogen sulfide inlet 0013, an exhaust outlet 0014, and a first material outlet 0016. The first housing contains a gas distribution assembly 0015, a stripping assembly, and two liquid guide plates located on either side of the gas distribution assembly. The gas distribution assembly includes a membrane support and a curtain-type hydrophobic hollow fiber membrane fixed by the membrane support. The membrane support includes a cavity that communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane. The hydrogen sulfide gas supply unit 005 communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane through the hydrogen sulfide inlet 0013 of the first housing and the cavity of the membrane support. The stripping assembly is used to strip solids from the surface of the hydrophobic hollow fiber membrane and deliver them to the catalyst production unit 002.

[0075] The catalyst production unit 002 includes a second housing, on which a second material inlet 0021, a third material inlet 0022 and a catalyst outlet 0023 are provided. A Joule hot flash evaporation device 0021 is provided inside the second housing. The first material outlet 0016 is connected to the second material inlet 0021.

[0076] See the structural schematic diagram of the water purification unit 003. Figure 3 It includes a third shell, on which a fourth material inlet 0031, a fifth material inlet 0032, an industrial wastewater inlet 0033, and a purified water outlet 0034 are provided. A stirring device 0035 is provided inside the third shell. The catalyst outlet on the second shell is connected to the fourth material inlet 0031, and the fifth material inlet 0032 is connected to the oxidant outlet of the oxidant supply unit.

[0077] See the structural schematic diagram of separation unit 004. Figure 3 The separation unit includes a fourth housing, which has a liquid inlet 0041, a liquid outlet 0042, and a sludge outlet 0043. A separation membrane 0045 is provided in the separation chamber. The liquid inlet 0041 and the liquid outlet 0042 are located on opposite sides of the separation membrane. The sludge outlet 0043 is located on the same side of the separation membrane as the liquid inlet 0041. The liquid inlet 0041 is connected to the outlet 0012 of the first housing, and the liquid outlet 0041 is connected to the industrial wastewater inlet 0033 of the third housing.

[0078] Comparative Example 1

[0079] This example provides a device for recycling heavy metals in industrial wastewater, which is basically the same as in Example 1, except that the Joule heat flash evaporation device 0021 in the second shell is replaced with a traditional tubular furnace.

[0080] Experimental Example 1

[0081] This example provides a method for recovering heavy metals from industrial wastewater using the apparatus of Example 1. The industrial wastewater used in this example contains heavy metal ions such as copper, cobalt, and nickel, with concentrations of 50 g / L, 100 mg / L, and 20 mg / L, respectively, and the COD in the wastewater is approximately 1000 mg / L. The specific steps include:

[0082] 1) Hydrogen sulfide gas is introduced into the cavity of the hydrophobic hollow fiber membrane through hydrogen sulfide gas supply unit 005 (hydrogen sulfide gas flow rate is 0.4 m³ / s). 3 / h);

[0083] 2) The industrial wastewater to be treated enters the heavy metal ion recovery unit through the inlet 0011 of the first shell and comes into full contact with the surface of the hydrophobic hollow fiber membrane to react and generate metal sulfides; at the same time, the industrial wastewater flows into the separation unit 004 through the outlet 0012 for separation, and the separated industrial wastewater flows into the water purification unit 003.

[0084] 3) The stripping assembly strips the metal sulfides (particle size 1-3 mm) from the surface of the hydrophobic hollow fiber membrane and sequentially sends them to the catalyst production unit 002 through the first material outlet 0016 and the second material inlet 0021. Biochar (particle size 1-3 mm) is sent to the catalyst production unit through the third material inlet 0022. The metal sulfides and carbon materials are mixed in the catalyst production unit, wherein the mass ratio of metal sulfides to carbon materials is 1:6. The mixture is then heat-treated by the Joule heat flash evaporation equipment 0024 to obtain a graphene catalyst loaded with metal sulfides. The heat treatment includes the following process: starting from room temperature, the temperature is raised to 600°C after 3 seconds, held for 50 seconds, and then raised again for 3 seconds to 1000°C, held for 50 seconds.

[0085] 4) The graphene catalyst loaded with metal sulfides enters the water purification unit 003 through the fourth material inlet 0031, and the 200 mg / L hydrogen peroxide solution enters the water purification unit 003 through the fourth material inlet 0032. Stirring is performed using inlet 0035, thus purifying the industrial wastewater. Testing shows that after treatment, the concentrations of heavy metal ions such as copper, cobalt, and nickel in the industrial wastewater are all below 0.5 mg / L, and the COD is reduced to 100–200 mg / L.

[0086] Experimental Example 2

[0087] This example provides a method for recovering heavy metals from industrial wastewater using the apparatus of Example 1. The industrial wastewater used in this example contains a molybdenum ion concentration of 1-2 g / L and a COD of approximately 200 mg / L. The specific steps include:

[0088] 1) Hydrogen sulfide gas is introduced into the cavity of the hydrophobic hollow fiber membrane through the hydrogen sulfide gas supply unit 005 (hydrogen sulfide gas flow rate is 1 m³ / min).3 / h);

[0089] 2) The industrial wastewater to be treated enters the heavy metal ion recovery unit through the inlet 0011 of the first shell and comes into full contact with the surface of the hydrophobic hollow fiber membrane to react and generate metal sulfides; at the same time, the industrial wastewater flows into the separation unit 004 through the outlet 0012 for separation, and the separated industrial wastewater flows into the water purification unit 003.

[0090] 3) The stripping assembly strips the metal sulfides (particle size 3-5 mm) from the surface of the hydrophobic hollow fiber membrane and sequentially sends them to the catalyst production unit 002 through the first material outlet 0016 and the second material inlet 0021. Biochar (particle size 3-5 mm) is sent to the catalyst production unit through the third material inlet 0022. The metal sulfides and carbon materials are mixed in the catalyst production unit, wherein the mass ratio of metal sulfides to carbon materials is 1:10. The mixture is then heat-treated by the Joule heat flash evaporation equipment 0024 to obtain a graphene catalyst loaded with metal sulfides. The heat treatment includes the following process: starting from room temperature, the temperature is raised to 800°C after 5 seconds, held for 30 seconds, and then raised again for 5 seconds to 1200°C, held for 40 seconds.

[0091] 4) The graphene catalyst loaded with metal sulfides enters the water purification unit 003 through the fourth material inlet 0031, and the 300 mg / L persulfate solution enters the water purification unit 003 through the fourth material inlet 0032. Stirring is performed using inlet 0035, thus purifying the industrial wastewater. Testing shows that after treatment, the concentration of molybdenum ions in the industrial wastewater is below 1 mg / L, and the COD is reduced to 50–80 mg / L.

[0092] Comparative Test Example 1

[0093] The apparatus used in Comparative Example 1 was employed to recover heavy metals from industrial wastewater. The method was essentially the same as in Experimental Example 1, except that the metal sulfides and carbon materials were heat-treated in a tubular furnace to obtain a graphene catalyst loaded with metal sulfides. The heat treatment included the following steps: starting from room temperature, the temperature was raised to 1000℃ after 15 minutes, held at that temperature for 30 minutes, and then lowered to room temperature after 90 minutes, during which nitrogen gas was introduced at a flow rate of 1 L / min to maintain an inert atmosphere. Testing showed that the COD of the treated industrial wastewater decreased to 600–700 mg / L.

[0094] Comparative Test Example 2

[0095] Similar to Example 1, the only difference is that the Joule flash evaporation equipment 0024 was not used for heat treatment; instead, metal sulfides were used directly as catalysts. Testing showed that the COD of the treated industrial wastewater decreased to 800–900 mg / L.

[0096] Comparative Test Example 3

[0097] Similar to Example 1, the only difference is that the Joule flash evaporation equipment 0024 performs the heat treatment process as follows: starting from room temperature, the temperature is raised once, reaching 1500℃ after 10 seconds, and held for 0–60 seconds, without a second temperature increase. Testing showed that the COD of the treated industrial wastewater decreased to 300–400 mg / L.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for recovering heavy metals from industrial wastewater using a device, characterized in that, This includes the use of a device to recover and utilize heavy metals from industrial wastewater, the device comprising a heavy metal recovery unit and a catalyst production unit; The heavy metal recovery unit includes a first housing, which has a water inlet, a water outlet, a hydrogen sulfide inlet, an exhaust outlet, and a first material outlet. The first housing contains an air distribution assembly and a stripping assembly. The air distribution assembly includes a hydrophobic hollow fiber membrane, and the hydrogen sulfide inlet communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane. The catalyst production unit includes a second shell, which is provided with a second material inlet, a third material inlet and a catalyst outlet, and is equipped with a Joule heat flash evaporator inside the second shell; The first material outlet is connected to the second material inlet; The stripping assembly includes a drive unit and a stripping unit, which are electrically connected. The drive unit is used to drive the stripping unit to strip the solids attached to the surface of the hydrophobic hollow fiber membrane and to transport the stripped solids to the catalyst outlet. The first housing is also provided with at least two liquid guide plates, which are located on both sides of the gas distribution assembly; The method includes the following steps: 1) Hydrogen sulfide gas is introduced into the cavity of the hydrophobic hollow fiber membrane through the hydrogen sulfide gas supply unit; 2) The industrial wastewater to be treated enters the heavy metal ion recovery unit through the inlet of the first shell and comes into full contact with the surface of the hydrophobic hollow fiber membrane to react and generate metal sulfides. 3) The stripping component strips the metal sulfide from the surface of the hydrophobic hollow fiber membrane and sends it to the catalyst production unit in sequence through the first material outlet and the second material inlet. The carbon material is sent to the catalyst production unit through the third material inlet. The metal sulfide and carbon material are mixed in the catalyst production unit and heat-treated by the Joule heat flash evaporation equipment to obtain the graphene catalyst loaded with metal sulfide.

2. The method according to claim 1, characterized in that, Also includes: The step involves purifying industrial wastewater discharged from the outlet of the first housing by contacting a mixture of a graphene catalyst and an oxidant containing the loaded metal sulfide.

3. The method according to claim 2, characterized in that, The mass ratio of the graphene catalyst loaded with metal sulfides to the oxidant is 1~50:

1.

4. The method according to claim 1, characterized in that, The mass ratio of the metal sulfide precipitate to the carbon material is 1:1 to 10.

5. The method according to claim 1, characterized in that, The heat treatment includes the following process: starting from room temperature, the temperature is raised to 300-1500℃ after 3-5 seconds, held for 1-60 seconds, and then raised again to 500-2000℃ after 3-5 seconds, held for 1-60 seconds.

6. The method according to claim 1, characterized in that, It also includes a water purification unit and an oxidant supply unit. The water purification unit includes a third housing, which is provided with a fourth material inlet, a fifth material inlet, an industrial wastewater inlet, and a purified water outlet. A stirring device is provided inside the third housing. The catalyst outlet on the second housing is connected to the fourth material inlet, and the fifth material inlet is connected to the oxidant outlet of the oxidant supply unit. And / or, the purified water outlet and the water inlet on the first housing are connected by a detachable pipe.

7. The method according to claim 6, characterized in that, It also includes a separation unit, which includes a fourth housing with a liquid inlet, a liquid outlet and a sludge outlet; a separation membrane is provided in the separation chamber; the liquid inlet and the liquid outlet are located on opposite sides of the separation membrane; the sludge outlet and the liquid inlet are located on the same side of the separation membrane; the liquid inlet is connected to the outlet of the first housing; and the liquid outlet is connected to the industrial wastewater inlet of the third housing.

8. The method according to any one of claims 6-7, characterized in that, The gas distribution assembly includes a membrane support and a hydrophobic hollow fiber membrane fixed by the membrane support. The membrane support includes a cavity that communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane. The hydrogen sulfide inlet communicates with the hollow inner cavity of the hydrophobic hollow fiber membrane through the cavity of the membrane support.

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