A tubular electrocatalytic membrane assembly filled with particle electrodes and its application

Abstract

The present invention provides a tubular electrocatalytic membrane assembly filled with particle electrodes and its application. The tubular electrocatalytic membrane assembly filled with particle electrodes includes a tubular electrocatalytic membrane and an oxygen vacancy particle electrode filled in the inner cavity of the tubular electrocatalytic membrane. The tubular electrocatalytic membrane is a cylindrical tubular electrocatalytic membrane with a single end, one end of which is closed and the other end is open. A adapter is installed at the opening of the tubular electrocatalytic membrane, and the adapter is provided with an inner cathode. One end of the inner cathode is inserted into the interior of the oxygen vacancy particle electrode, and the other end extends through the outside of the adapter to the outside of the tubular electrocatalytic membrane. The surface of the inner cathode is coated with an insulating layer. The tubular electrocatalytic membrane assembly filled with particle electrodes proposed by the present invention has a large electrochemical reaction area and active species generation capacity, can quickly and efficiently degrade organic matter in salt-containing refractory organic wastewater, and is particularly suitable for treating high-concentration refractory organic wastewater.

Description

Technical Field

[0001] The present invention relates to the field of water treatment materials, and in particular to a tubular electrocatalytic membrane assembly filled with particle electrodes and applications thereof. Background Art

[0002] The treatment of refractory organic wastewater has always been a challenge in the field of environmental engineering. Due to the low biodegradability of refractory organic matter, traditional biological treatment methods are unable to effectively remove it. Advanced oxidation technologies (ADTs) utilize highly oxidizing active species to rapidly degrade refractory organic pollutants, and electrocatalytic oxidation (ECO) has garnered significant attention from researchers. Compared to other ADTs, ECO utilizes electrons as a cleaning agent, eliminating the need for chemical reagents. It is environmentally friendly, simple to operate, and widely applicable.

[0003] In recent years, electrocatalytic membrane technology, which combines electrocatalytic oxidation with membrane technology, has become a research hotspot in this field. Electrocatalytic membranes act as both electrodes and filter materials in wastewater treatment, treating wastewater as it flows through the membrane. Compared to traditional electrocatalytic oxidation technology, electrocatalytic membranes increase the catalyst loading area and enhance the mass transfer rate of reactants, promoting electrode reactions. Consequently, electrocatalytic membranes offer greater removal efficiency for organic pollutants while consuming less power.

[0004] Currently, there are two main types of electrocatalytic membranes: plate-type and tubular. Different electrocatalytic membrane types have different requirements for reactor construction. To allow wastewater to flow through the electrocatalytic membrane, two cavities, an inlet and an outlet, need to be formed within the reactor. Because the tubular electrocatalytic membrane has its own internal cavity, the sealing between the membrane and the reactor wall is eliminated during reactor construction, making it easy to manufacture and scale up. However, since the counter electrode of a tubular electrocatalytic membrane is typically located outside the membrane, the electrode area within the membrane is not fully utilized. It is worth noting that, in addition to collecting treated wastewater, the internal cavity of the tubular electrocatalytic membrane can also serve as a space for granular electrodes, thereby increasing the electrode reaction area. Therefore, developing a device combining tubular electrocatalytic membranes and granular electrodes is of great significance for improving the treatment of difficult-to-degrade organic wastewater and reducing energy consumption. Summary of the Invention

[0005] In view of this, the present invention aims to provide a tubular electrocatalytic membrane assembly filled with particle electrodes and its application.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] In the first aspect, the present invention provides a tubular electrocatalytic membrane assembly filled with particle electrodes, comprising a tubular electrocatalytic membrane and an oxygen vacancy particle electrode filled in the inner cavity of the tubular electrocatalytic membrane, wherein the tubular electrocatalytic membrane is a single-ended cylindrical tubular electrocatalytic membrane, one end of which is closed and the other end is open; a adapter is installed at the opening of the tubular electrocatalytic membrane, and an inner cathode is provided on the adapter, one end of the inner cathode is inserted into the interior of the oxygen vacancy particle electrode, and the other end passes through the outside of the conversion head and extends to the outside of the tubular electrocatalytic membrane, and the surface of the inner cathode is wrapped with an insulating layer.

[0008] Preferably, the oxygen vacancy particle electrode is oxygen vacancy antimony tin oxide particles or oxygen vacancy lead oxide particles.

[0009] Furthermore, the oxygen vacancy particle electrode is prepared by the following steps:

[0010] (1) Nano-oxide powder with a particle size of 20-40 nm is mixed with a pore-forming agent and a binder to obtain a mixture;

[0011] (2) Place the mixture into a spherical mold with a diameter of 5-7 mm and compact it using a tablet press;

[0012] (3) The compacted particles are removed from the mold and placed in a muffle furnace, heated to 600-800 °C, and calcined at a constant temperature for 6-8 h;

[0013] (4) The calcined particles were immersed in NaBH4 solution for reduction for 10-20 min, and finally washed and dried to obtain oxygen vacancy particle electrodes.

[0014] Introducing oxygen vacancies into nano-oxides can help improve the electrocatalytic oxidation activity of particle electrodes and increase the yield of active species.

[0015] Preferably, the mass ratio of the nano-oxide powder to the pore-forming agent is (3-5):1.

[0016] Preferably, the mass ratio of the nano oxide powder to the binder is (8-10): 1

[0017] Preferably, the concentration of the NaBH4 solution is 0.5~1.5 mol / L.

[0018] Preferably, the nano oxide powder is one of nano antimony tin oxide powder and nano lead oxide particles, or a mixture of the two.

[0019] Preferably, the pore-forming agent is one or a mixture of two or more of (NH4)2CO3, NH4HCO3, and polyvinyl butyral.

[0020] Preferably, the binder is one or a mixture of two or more of paraffin oil, coal tar, and carboxymethyl cellulose.

[0021] Furthermore, the tubular electrocatalytic membrane is made of titanium membrane or carbon membrane, has a pore size between 0.5 and 50 μm, an outer diameter between 3 and 15 cm, and a membrane thickness between 2 and 3 mm.

[0022] Furthermore, the tubular electrocatalytic membrane is an electrocatalytic membrane obtained by loading metal nanocatalysts onto a titanium membrane or a carbon membrane. Specifically, it can be prepared by loading metal nanocatalysts onto a commercial titanium membrane or a carbon membrane via a sol-gel method or an electrodeposition method.

[0023] Preferably, the metal nanocatalyst is one or a mixture of two or more of SnO2-Sb, TiO2, PbO2, and manganese oxide.

[0024] Furthermore, the inner cathode is a titanium wire, stainless steel wire or graphite rod with a diameter less than 5 mm, and the inner cathode is embedded in the middle of the inner cavity of the tubular electrocatalytic membrane.

[0025] Furthermore, the insulating layer has a thickness of less than 1 mm.

[0026] Furthermore, a plurality of through holes are opened on the surface of the insulating layer, the aperture of the through holes is 1-3 mm, and the opening rate is between 60% and 80%.

[0027] Furthermore, the insulating layer is a plastic layer.

[0028] The electric field formed between the inner cathode and the tubular electrocatalytic membrane can stimulate the oxygen vacancy particle electrode to produce active species and enhance the oxidation capacity.

[0029] The purpose of the insulating layer is to prevent short circuits inside the module, and the purpose of opening holes in it is to avoid open circuits inside the module.

[0030] The adapter serves to fix the inner cathode and connect the electrocatalytic membrane anode with the external pipeline, and a passage for the treated wastewater to flow out is provided inside the adapter.

[0031] In a second aspect, the present invention provides an application of the above-mentioned tubular electrocatalytic membrane assembly filled with particle electrodes in treating salt-containing refractory organic wastewater.

[0032] In a third aspect, the present invention further provides a device for treating salt-containing refractory organic wastewater, wherein the device uses the above-mentioned tubular electrocatalytic membrane module filled with particle electrodes.

[0033] Furthermore, the device includes a tubular electrocatalytic membrane assembly filled with particle electrodes, a cylindrical outer cathode, a cylindrical reactor, a DC power supply and a pipeline, wherein the tubular electrocatalytic membrane assembly filled with particle electrodes is placed in the cylindrical reactor, the cylindrical outer cathode is arranged between the tubular electrocatalytic membrane assembly filled with particle electrodes and the cylindrical reactor and is sleeved on the outside of the tubular electrocatalytic membrane assembly filled with particle electrodes, the tubular electrocatalytic membrane assembly filled with particle electrodes is connected to the anode of the DC power supply, the inner cathode and the cylindrical outer cathode of the tubular electrocatalytic membrane assembly filled with particle electrodes are both connected to the cathode of the DC power supply, one end of the pipeline is connected to the adapter, and the other end is connected to the cylindrical reactor, and a pump is provided in the pipeline.

[0034] Furthermore, the pump is a peristaltic pump.

[0035] Furthermore, the distance between the tubular electrocatalytic membrane assembly filled with particle electrodes and the cylindrical outer cathode is 1-3 cm, and the height of the cylindrical outer cathode is 1-2 cm greater than the height of the tubular electrocatalytic membrane assembly filled with particle electrodes.

[0036] Furthermore, the current provided by the DC power supply is 15-30 mA / cm 2 between.

[0037] The working process and working principle of the above device are as follows:

[0038] A tubular electrocatalytic membrane assembly filled with granular electrodes is placed in a cylindrical reactor. A cylindrical outer cathode is placed on the outside of the tubular electrocatalytic membrane assembly filled with granular electrodes. The tubular electrocatalytic membrane assembly filled with granular electrodes is connected to the anode of a DC power supply, and the inner and outer cathodes are connected to the cathode of the DC power supply. An adapter is connected to the pipeline. Under the action of an external voltage, the salt-containing, difficult-to-degrade organic wastewater in the cylindrical reactor is treated to degrade the organic matter in the salt-containing, difficult-to-degrade organic wastewater. Under the suction of a peristaltic pump, the salt-containing, difficult-to-degrade organic wastewater passes through the tubular electrocatalytic membrane and granular electrodes in sequence, flows out of the pipeline, and then returns to the cylindrical reactor, repeating the cycle.

[0039] The conductivity of the saline-containing refractory organic wastewater is greater than 3 mS / cm and can be as high as 100 mS / cm, and the COD concentration can be as high as 2000 mg / L.

[0040] Compared with the prior art, the tubular electrocatalytic membrane assembly filled with particle electrodes described in the present invention has the following advantages:

[0041] (1) The tubular electrocatalytic membrane assembly filled with particle electrodes described in the present invention has a larger electrochemical reaction active area. Under the stimulation of the electric field formed between the inner cathode and the electrocatalytic membrane, the particle electrodes filled in the inner cavity of the tubular electrocatalytic membrane can also undergo electrochemical reactions on their surface to produce active species, thereby degrading difficult-to-degrade organic matter in the wastewater. At the same time, the inner cathode can also stimulate the active sites on the inner side of the tubular electrocatalytic membrane to produce catalytic degradation of organic matter. Through the combined action of the above two aspects, the electrochemical reaction active area of the electrode is greatly increased, which is conducive to increasing the reaction rate and reducing energy consumption.

[0042] (2) The introduction of oxygen vacancies in the tubular electrocatalytic membrane assembly filled with particle electrodes described in the present invention can further increase the yield of active species. The present invention uses NaBH4 to reduce the particle electrodes, a process that can introduce oxygen vacancies into the lattice structure. After the oxygen vacancies are introduced, under the action of electric field excitation, the particle electrodes can produce higher concentrations of active species such as ·OH, thereby increasing the degradation rate of organic matter and reducing energy consumption. In addition, the method of introducing oxygen vacancies by NaBH4 reduction is also simple and rapid to operate.

[0043] (3) Due to the large electrochemical active area and high yield of active species, the tubular electrocatalytic membrane device filled with particle electrodes described in the present invention is particularly suitable for the treatment of high-concentration, difficult-to-degrade organic wastewater. The initial COD of the treated wastewater can be as high as 2000 mg / L, and the removal rate can reach more than 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0045] Figure 1 Schematic diagram of the structure of a tubular electrocatalytic membrane assembly filled with particle electrodes;

[0046] Figure 2 X-ray photoelectron spectroscopy of SnO2-Sb particle electrode with oxygen vacancies;

[0047] Figure 3 Schematic diagram of the structure of the device for treating saline-containing refractory organic wastewater (the arrow indicates the flow direction of saline-containing refractory organic wastewater);

[0048] Figure 4 The tubular electrocatalytic membrane device filled with granular electrodes is used to remove organic matter from reverse osmosis concentrated water of printing and dyeing wastewater;

[0049] Figure 5Comparison of the organic matter removal effects of comparative application examples 1 to 5 with those of application example 1 (T is the result of comparative application example 1; T+IC is the result of comparative application example 2; T+P+IC is the result of comparative application example 3; T+P OV +IC is the result of application example 1; T+P OV* +IC is the result of comparative application example 4; T+P OV** +IC is the result of comparative application example 5; T, IC, P, P OV Represent the electrocatalytic membrane, inner cathode, particle electrode without oxygen vacancies, and particle electrode with oxygen vacancies, respectively. The * represents the oxygen vacancy particle electrode obtained by reduction outside the NaBH4 concentration range).

[0050] Reference numerals:

[0051] 1. Tubular electrocatalytic membrane assembly filled with particle electrodes; 1-1. Tubular electrocatalytic membrane; 1-2. Oxygen vacancy SnO2-Sb particle electrode; 1-3. Inner cathode; 1-4. Perforated insulating layer; 1-5. Adapter; 2. Cylindrical outer cathode; 3. Cylindrical reactor; 4. DC power supply; 5. Piping; 6. Peristaltic pump. DETAILED DESCRIPTION

[0052] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0053] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0054] Example 1

[0055] A tubular electrocatalytic membrane assembly filled with particle electrodes comprises a tubular electrocatalytic membrane 1-1, an oxygen-vacancy SnO2-Sb particle electrode 1-2 filled within the tubular electrocatalytic membrane 1-1, an inner cathode 1-3 embedded within the membrane to stimulate the oxygen-vacancy SnO2-Sb particle electrode 1-2, an open-pored insulating layer 1-4 wrapped around the surface of the inner cathode 3, and an adapter 1-5. The tubular electrocatalytic membrane 1-1 is a cylindrical, single-ended tubular electrocatalytic membrane with one closed end and the other open. The adapter 1-5 is mounted at the opening. One end of the inner cathode 1-3 is inserted into the interior of the oxygen-vacancy SnO2-Sb particle electrode 1-2, while the other end extends through the exterior of the adapter to the exterior of the tubular electrocatalytic membrane 1-1.

[0056] The oxygen vacancy SnO2-Sb particle electrode is prepared by the following steps:

[0057] (1) Take 4 g of nano-antimony tin oxide (SnO2 / Sb2O3) powder with a particle size of 20-40 nm, 1.2 g of (NH4)2CO3 (as a pore-forming agent), and 0.4 g of paraffin oil (as a binder) and mix them evenly. The mass ratio of nano-antimony tin oxide to (NH4)2CO3 is 3.3:1, and the mass ratio of nano-antimony tin oxide to paraffin oil is 10:1.

[0058] (2) Place the mixture into a spherical mold with a diameter of 6 mm and compact it using a tablet press;

[0059] (3) The compacted particles were removed from the mold and placed in a muffle furnace, heated to 800 °C at a heating rate of 2 °C / min, and calcined at 800 °C for 6 h.

[0060] (4) The calcined particles were immersed in 1 mol / L NaBH4 solution for reduction for 10 min, and finally washed and dried to obtain oxygen vacancy SnO2-Sb particle electrodes.

[0061] The tubular electrocatalytic membrane 1-1 is an electrocatalytic membrane (SnO2-Sb / Ti tubular electrocatalytic membrane) obtained by loading SnO2-Sb nanocatalyst onto a tubular titanium membrane. The pore size of the titanium membrane is 20 µm, the outer diameter of the titanium membrane is 3 cm, the wall thickness is 2 mm, and the height is 6 cm.

[0062] The inner cathode 1-3 is a stainless steel wire with a diameter of 2 mm, and the inner cathode 1-3 is embedded in the middle of the inner cavity of the tubular electrocatalytic membrane 1-1.

[0063] The open-pore insulating layers 1-4 are non-woven plastic layers with a thickness of less than 1 mm, an open-pore diameter of 1-3 mm, and an open-pore ratio of 60%-80%.

[0064] The adapter 1-5 serves to fix the inner cathode 1-3 and connect the electrocatalytic membrane anode with the external pipeline.

[0065] Figure 1 This is a schematic diagram of the structure of a tubular electrocatalytic membrane module filled with particle electrodes. Figure 2 The X-ray photoelectron spectrum of SnO2-Sb particle electrode with oxygen vacancies is shown in Figure 2. Figure 2 It can be seen that compared with the SnO2-Sb particle electrode that has not been reduced by NaBH4, Sn appears in the XPS spectrum of the SnO2-Sb particle electrode after NaBH4 reduction. 2+The characteristic peaks of SnO2-Sb are observed, indicating the generation of oxygen vacancies. Simultaneously, the characteristic peaks of the Sn 3d orbitals shift negatively toward lower binding energies, indicating that oxygen vacancies alter the surface electronic structure of SnO2-Sb (i.e., the electron density around Sn increases). These results indicate that oxygen vacancies are generated in the SnO2-Sb lattice structure after NaBH4 reduction, indicating that oxygen-vacancy SnO2-Sb particle electrodes have been prepared.

[0066] Example 2

[0067] The tubular electrocatalytic membrane assembly filled with granular electrodes in this embodiment is basically the same as that in Example 1, except that the mass ratio of nano-antimony tin oxide to NH4HCO3 is 3:1, the mass ratio of nano-antimony tin oxide to coal tar is 8:1, the heating rate is 5°C / min to 600°C, the calcination temperature is 600°C, and the concentration of NaBH4 solution is 0.5 mol / L.

[0068] Example 3

[0069] The tubular electrocatalytic membrane assembly filled with particle electrodes in this embodiment is basically the same as that in Example 1, except that the mass ratio of nano-antimony tin oxide to polyvinyl butyral is 5:1, the mass ratio of nano-antimony tin oxide to carboxymethyl cellulose is 9:1, the heating rate is 1°C / min to 700°C, the calcination temperature is 700°C, and the concentration of the NaBH4 solution is 1.5 mol / L.

[0070] Example 4

[0071] The tubular electrocatalytic membrane assembly filled with particle electrodes in this embodiment is basically the same as that in Example 1, except that: the tubular electrocatalytic membrane is filled with oxygen vacancy PbO2 particle electrodes, and the nano-oxide used in the preparation process of the oxygen vacancy PbO2 particle electrodes is nano-lead oxide, and the oxygen vacancy PbO2 particle electrodes are prepared.

[0072] Comparative Example 1

[0073] The purpose of Comparative Example 1 is to illustrate that the addition of a granular electrode and an inner cathode can enhance the degradation of organic matter. In Comparative Example 1, the anode used is the SnO2-Sb / Ti tubular electrocatalytic membrane in Example 1 with the granular electrode and the inner cathode removed.

[0074] Comparative Example 2

[0075] The purpose of Comparative Example 2 is to further illustrate the importance of particle electrodes in improving the removal of organic matter. In Comparative Example 2, the SnO2-Sb oxygen vacancy particle electrode in Example 1 was removed, and only the inner cathode was retained to construct an electrocatalytic membrane assembly.

[0076] Comparative Example 3

[0077] Comparative Example 3 aims to demonstrate that the introduction of oxygen vacancies improves the removal of organic matter. In Comparative Example 3, an electrocatalytic membrane assembly was constructed using a particle electrode without oxygen vacancies (i.e., the SnO2-Sb particle electrode not treated with NaBH4 in Example 1) instead of the SnO2-Sb particle electrode with oxygen vacancies in Example 1.

[0078] Comparative Example 4

[0079] The tubular electrocatalytic membrane assembly filled with particle electrodes in this comparative example is basically the same as that in Example 1, except that the concentration of the NaBH4 solution is 2 mol / L.

[0080] Comparative Example 5

[0081] The tubular electrocatalytic membrane assembly filled with particle electrodes in this comparative example is basically the same as that in Example 1, except that the concentration of the NaBH4 solution is 0.4 mol / L.

[0082] The present invention also provides a device for treating salt-containing refractory organic wastewater, such as Figure 3 As shown, the device includes a tubular electrocatalytic membrane assembly 1 filled with particle electrodes, a cylindrical outer cathode 2, a cylindrical reactor 3, a DC power supply 4 and a pipeline 5. The tubular electrocatalytic membrane assembly 1 filled with particle electrodes is placed in the cylindrical reactor 3, the cylindrical outer cathode 2 is arranged between the tubular electrocatalytic membrane assembly 1 filled with particle electrodes and the cylindrical reactor 3 and is sleeved on the outside of the tubular electrocatalytic membrane assembly 1 filled with particle electrodes, the tubular electrocatalytic membrane assembly 1 filled with particle electrodes is connected to the anode of the DC power supply 4, the inner cathode of the tubular electrocatalytic membrane assembly 1 filled with particle electrodes and the cylindrical outer cathode 2 are both connected to the cathode of the DC power supply 4, one end of the pipeline is connected to the adapter 1-5, and the other end is connected to the cylindrical reactor 3, and a pump is provided in the pipeline 5.

[0083] Application Example 1

[0084] The tubular electrocatalytic membrane assembly 1 filled with granular electrodes prepared in Example 1 was placed in a cylindrical reactor 3. A cylindrical outer cathode 2 was placed on the outside of the tubular electrocatalytic membrane assembly 1. The tubular electrocatalytic membrane 1-1 was connected to the anode of a DC power supply 4. The inner cathode 1-3 and the cylindrical outer cathode 2 were connected to the cathode of the DC power supply 4. An adapter 1-5 was connected to a pipeline 5, which was equipped with a peristaltic pump 6. Under the action of an applied voltage, the reverse osmosis concentrate of the printing and dyeing wastewater in the cylindrical reactor 3 was treated to degrade organic matter in the wastewater.

[0085] The conductivity of the reverse osmosis concentrated water of printing and dyeing wastewater is 5 mS / cm, and the COD concentration is about 1150 mg / L. Under the suction of the peristaltic pump 6, the wastewater passes through the tubular electrocatalytic membrane 1-1 and the oxygen vacancy SnO2-Sb particle electrode 1-2 in sequence, then flows out from the pipeline 5 and returns to the cylindrical reactor 3, repeating the cycle.

[0086] The distance between the tubular electrocatalytic membrane assembly 1 filled with granular electrodes and the cylindrical outer cathode 2 is 1 cm, and the height of the cylindrical outer cathode 2 is 2 cm greater than the height of the assembly. The current provided by the DC power supply 4 is 20 mA / cm 2 .

[0087] Figure 4 The COD concentration changes during the reverse osmosis treatment of printing and dyeing wastewater concentrate. With increasing reaction time, the COD concentration showed a significant downward trend. After 3 hours of treatment, the COD concentration dropped from 1150 mg / L to 113 mg / L, achieving a removal efficiency of 89.8%. The effluent COD concentration was significantly below the limit of 200 mg / L specified in the "Discharge Standard of Water Pollutants for Textile Dyeing and Finishing Industries" (GB 4287-2012). The experimental results demonstrate that the use of a tubular electrocatalytic membrane module filled with granular electrodes is effective in removing organic matter from the reverse osmosis concentrate of printing and dyeing wastewater.

[0088] Comparative Application Example 1

[0089] The SnO2-Sb / Ti tubular electrocatalytic membrane prepared in Comparative Example 1 was assembled according to Application Example 1 to obtain a device for treating salt-containing refractory organic wastewater, which was used to treat reverse osmosis concentrated water from printing and dyeing wastewater. At the same current density as in Application Example 1, the COD removal effect of the SnO2-Sb / Ti tubular electrocatalytic membrane was as follows: Figure 5 After 3 hours of treatment, the COD removal rate was only 64.3%, significantly lower than the removal rate when filled with granular electrodes (89.8%, Application Example 1), confirming that the tubular electrocatalytic membrane module filled with granular electrodes has excellent performance in removing organic matter from wastewater.

[0090] Comparative Application Example 2

[0091] The tubular electrocatalytic membrane module prepared in Comparative Example 2 was assembled according to Application Example 1 to obtain a device for treating salt-containing refractory organic wastewater, which was used to treat reverse osmosis concentrated water from printing and dyeing wastewater. At the same current density as in Application Example 1, the final COD removal rate was only 69.2% ( Figure 5 ), which is lower than 89.8% of Application Example 1, indicating that the addition of particle electrodes helps to improve the removal effect of organic matter.

[0092] Comparative Application Example 3

[0093] The tubular electrocatalytic membrane module prepared in Comparative Example 3 was assembled according to Application Example 1 to obtain a device for treating salt-containing refractory organic wastewater, which was used to treat reverse osmosis concentrated water from printing and dyeing wastewater. At the same current density as in Application Example 1, the final COD removal rate was only 79.3% ( Figure 5), which is lower than 89.8% of Application Example 1, indicating that the introduction of oxygen vacancies helps to improve the removal effect of organic matter.

[0094] Comparative Application Example 4

[0095] The tubular electrocatalytic membrane module prepared in Comparative Example 4 was assembled according to Application Example 1 to create a device for treating saline, refractory organic wastewater. This device was used to treat reverse osmosis concentrate from printing and dyeing wastewater. At the same current density as in Application Example 1, the final COD removal rate was only 77.4%.

[0096] Comparative Application Example 5

[0097] The tubular electrocatalytic membrane module prepared in Comparative Example 5 was assembled according to Application Example 1 to create a device for treating saline, refractory organic wastewater. This device was then used to treat reverse osmosis concentrate from printing and dyeing wastewater. At the same current density as in Application Example 1, the final COD removal rate was only 81.5%.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tubular electrocatalytic membrane assembly filled with granular electrodes, characterized in that: It includes a tubular electrocatalytic membrane and an oxygen vacancy particle electrode filled in the inner cavity of the tubular electrocatalytic membrane. The tubular electrocatalytic membrane is a cylindrical tubular electrocatalytic membrane with a single end, one end of which is closed and the other end is open. A adapter is installed at the opening of the tubular electrocatalytic membrane, and an inner cathode is provided on the adapter. One end of the inner cathode is inserted into the interior of the oxygen vacancy particle electrode, and the other end passes through the outside of the adapter and extends to the outside of the tubular electrocatalytic membrane. The surface of the inner cathode is wrapped with an insulating layer. The oxygen vacancy particle electrode is oxygen vacancy antimony tin oxide particles or oxygen vacancy lead oxide particles.

2. The tubular electrocatalytic membrane assembly filled with particle electrodes according to claim 1, characterized in that: The oxygen vacancy particle electrode is prepared by the following steps: (1) Nano-oxide powder with a particle size of 20-40 nm is mixed with a pore-forming agent and a binder to obtain a mixture; (2) Place the mixture into a spherical mold with a diameter of 5-7 mm and compact it using a tablet press; (3) The compacted particles are removed from the mold and placed in a muffle furnace, heated to 600-800 °C, and calcined at a constant temperature for 6-8 h; (4) Immerse the calcined particles in NaBH4 solution for reduction for 10-20 min, and finally wash and dry them to obtain oxygen vacancy particle electrodes; The mass ratio of the nano-oxide powder to the pore-forming agent is (3-5):1; and / or The mass ratio of the nano-oxide powder to the binder is (8-10):1; and / or The concentration of the NaBH4 solution is 0.5 to 1.5 mol / L; and / or The nano oxide powder is one of nano antimony tin oxide powder and nano lead oxide particles or a mixture of both; and / or The pore-forming agent is one or a mixture of two or more of (NH4)2CO3, NH4HCO3, and polyvinyl butyral; and / or The binder is one or a mixture of two or more of paraffin oil, coal tar, and carboxymethyl cellulose.

3. The tubular electrocatalytic membrane assembly filled with particle electrodes according to claim 1, characterized in that: The tubular electrocatalytic membrane is made of titanium membrane or carbon membrane, has a pore size between 0.5 and 50 μm, an outer diameter between 3 and 15 cm, and a membrane thickness between 2 and 3 mm; and / or The tubular electrocatalytic membrane is an electrocatalytic membrane obtained by loading metal nanocatalysts onto a titanium membrane or a carbon membrane; The metal nanocatalyst is one or a mixture of two or more of SnO2-Sb, TiO2, PbO2 and manganese oxide.

4. The tubular electrocatalytic membrane assembly filled with particle electrodes according to claim 1, characterized in that: The inner cathode is a titanium wire, stainless steel wire or graphite rod with a diameter less than 5 mm, and is embedded in the middle of the inner cavity of the tubular electrocatalytic membrane.

5. The tubular electrocatalytic membrane assembly filled with particle electrodes according to claim 1, characterized in that: The thickness of the insulating layer is less than 1 mm.

6. The tubular electrocatalytic membrane assembly filled with particle electrodes according to claim 1, characterized in that: The surface of the insulating layer is provided with a plurality of through holes, the aperture of the through holes is 1-3 mm, and the opening rate is between 60% and 80%.

7. Use of the tubular electrocatalytic membrane assembly filled with particle electrodes according to any one of claims 1 to 6 in treating saline-containing refractory organic wastewater.

8. A device for treating saline refractory organic wastewater, characterized by: A tubular electrocatalytic membrane assembly using the particle electrode filled as claimed in any one of claims 1 to 6.

9. The device according to claim 8, characterized in that: The device includes a tubular electrocatalytic membrane assembly filled with particle electrodes, a cylindrical outer cathode, a cylindrical reactor, a DC power supply and a pipeline. The tubular electrocatalytic membrane assembly filled with particle electrodes is placed in the cylindrical reactor. The cylindrical outer cathode is arranged between the tubular electrocatalytic membrane assembly filled with particle electrodes and the cylindrical reactor and is sleeved on the outside of the tubular electrocatalytic membrane assembly filled with particle electrodes. The tubular electrocatalytic membrane assembly filled with particle electrodes is connected to the anode of the DC power supply. The inner cathode and the cylindrical outer cathode of the tubular electrocatalytic membrane assembly filled with particle electrodes are both connected to the cathode of the DC power supply. One end of the pipeline is connected to the adapter and the other end is connected to the cylindrical reactor. A pump is provided in the pipeline.

10. The device according to claim 9, characterized in that: The distance between the tubular electrocatalytic membrane assembly filled with particle electrodes and the cylindrical outer cathode is 1 to 3 cm; and / or The height of the cylindrical outer cathode is 1-2 cm greater than the height of the tubular electrocatalytic membrane assembly filled with granular electrodes; and / or The current provided by the DC power supply is 15-30 mA / cm 2 between.

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