Tubular electro-catalysis membrane module filled with particle electrodes and application of tubular electro-catalysis membrane module

Abstract

The invention provides a tubular electro-catalysis membrane module filled with particle electrodes and application thereof.The tubular electro-catalysis membrane module filled with the particle electrodes comprises a tubular electro-catalysis membrane and oxygen vacancy particle electrodes filled in an inner cavity of the tubular electro-catalysis membrane, the tubular electro-catalysis membrane is a cylindrical tubular electro-catalysis membrane with a single through end, one end of the tubular electro-catalysis membrane is closed, and the other end of the tubular electro-catalysis membrane is open. The other end is open; an adapter is installed at an opening of the tubular electro-catalytic membrane, an inner cathode is arranged on the adapter, one end of the inner cathode is inserted into the oxygen vacancy particle electrode, the other end of the inner cathode penetrates through the outside of the adapter and extends to the outside of the tubular electro-catalytic membrane, and the surface of the inner cathode is wrapped with an insulating layer. The tubular electro-catalysis membrane module filled with the particle electrode has a large electrochemical reaction area and active species generation capability, can rapidly and efficiently degrade organic matters in salt-containing degradation-resistant organic wastewater, and is especially suitable for treatment of high-concentration degradation-resistant organic wastewater.

Description

Technical Field

[0001] The present invention relates to the field of water treatment materials, and particularly to a tubular electrocatalytic membrane unit filled with particulate electrodes and its application. 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 substances, traditional biological treatment methods cannot effectively remove them. Advanced oxidation technologies can use strongly oxidizing active species to rapidly degrade refractory organic pollutants, among which electrocatalytic oxidation technology has received extensive attention from researchers. Compared with other advanced oxidation technologies, the advantage of electrocatalytic oxidation technology is that it uses electrons as clean reagents, avoiding the input of chemical agents, having strong environmental friendliness, and at the same time being simple to operate and widely applicable.

[0003] In recent years, the electrocatalytic membrane technology formed by combining electrocatalytic oxidation and membrane technology has been a research hotspot in this field. The electrocatalytic membrane serves both as an electrode and a filtration material when treating sewage, and the sewage is treated during the process of flowing through the electrocatalytic membrane. Compared with the traditional electrocatalytic oxidation technology, the electrocatalytic membrane can increase the catalyst loading area and improve the mass transfer rate of reactants, promoting the occurrence of electrode reactions. Therefore, the electrocatalytic membrane has a higher removal effect on organic pollutants and lower power consumption.

[0004] Currently, electrocatalytic membranes mainly have two forms, one is a plate-type electrocatalytic membrane, and the other is a tubular electrocatalytic membrane. Different forms of electrocatalytic membranes have different requirements for the reactor structure. In order to enable sewage to flow through the electrocatalytic membrane, it is necessary to form two cavities for influent and effluent in the reactor. Since the tubular electrocatalytic membrane has its own internal cavity, the sealing link between the electrocatalytic membrane and the reactor wall is omitted when constructing the reactor, making it easy to process, manufacture, and scale up. However, since the counter electrode of the tubular electrocatalytic membrane is usually arranged outside it, the electrode area inside the tubular electrocatalytic membrane cannot be fully utilized. It should be noted that in addition to being used to collect the treated sewage, the internal cavity of the tubular electrocatalytic membrane can also be used as a space for accommodating particulate electrodes, thereby increasing the electrode reaction area. Therefore, developing a combined device of a tubular electrocatalytic membrane and particulate electrodes is of great significance for improving the treatment effect of refractory 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 unit filled with particulate electrodes and its application.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows: In a first aspect, the present invention provides a tubular electrocatalytic membrane unit filled with particulate electrodes, comprising a tubular electrocatalytic membrane and an oxygen vacancy particulate electrode filled in the inner cavity of the tubular electrocatalytic membrane. 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 open end of the tubular electrocatalytic membrane, and an inner cathode is provided on the adapter. One end of the inner cathode is inserted into the oxygen vacancy particulate electrode, and the other end extends outside the tubular electrocatalytic membrane through the outside of the adapter. The surface of the inner cathode is wrapped with an insulating layer.

[0007] Preferably, the oxygen vacancy particulate electrode is an oxygen vacancy antimony tin oxide particulate or an oxygen vacancy lead oxide particulate.

[0008] Furthermore, the oxygen vacancy particulate electrode is prepared by the following steps: (1) Take nano-oxide powder with a particle size of 20 - 40 nm and mix it evenly with a pore former and a binder to obtain a mixture; (2) Put the mixture into a spherical mold with a diameter of 5 - 7 mm and compact it using a tablet press; (3) Take out the compacted particles from the mold and place them in a muffle furnace, heat to 600 - 800 °C, and keep calcining at a constant temperature for 6 - 8 h; (4) Immerse the calcined particles in a NaBH4 solution for reduction for 10 - 20 min, and finally wash and dry to obtain the oxygen vacancy particulate electrode.

[0009] Introducing oxygen vacancies into the nano-oxide helps to improve the electrocatalytic oxidation activity of the particulate electrode and increase the production of active species.

[0010] Preferably, the mass ratio of the nano-oxide powder to the pore former is (3 - 5):1.

[0011] Preferably, the mass ratio of the nano-oxide powder to the binder is (8 - 10):1 Preferably, the concentration of the NaBH4 solution is 0.5 - 1.5 mol / L.

[0012] Preferably, the nano-oxide powder is one or a mixture of two of nano-antimony tin oxide powder and nano-lead oxide particles.

[0013] Preferably, the pore former is one or a mixture of two or more of (NH4)2CO3, NH4HCO3, and polyvinyl butyral.

[0014] Preferably, the binder is one or a mixture of two or more of paraffin oil, coal tar pitch, and carboxymethyl cellulose.

[0015] Further, the material of the tubular electrocatalytic membrane is a titanium membrane or a carbon membrane, with a pore diameter between 0.5 and 50 µm, an outer diameter between 3 and 15 cm, and a membrane thickness between 2 and 3 mm.

[0016] Further, the tubular electrocatalytic membrane is an electrocatalytic membrane obtained by loading a metal nanocatalyst onto a titanium membrane or a carbon membrane. Specifically, it can be prepared by loading a metal nanocatalyst onto a commercial titanium membrane or carbon membrane through the sol-gel method or the electrodeposition method.

[0017] Preferably, the metal nanocatalyst is one or a mixture of two or more of SnO2-Sb, TiO2, PbO2, and manganese oxide.

[0018] Further, the inner cathode is a titanium wire, a stainless steel wire, or a graphite rod with a diameter less than 5 mm, and the inner cathode is embedded to half of the inner cavity of the tubular electrocatalytic membrane.

[0019] Further, the insulating layer has a thickness less than 1 mm.

[0020] Further, a number of through holes are provided on the surface of the insulating layer, the through holes have a pore diameter of 1 to 3 mm, and the porosity is between 60% and 80%.

[0021] Further, the insulating layer is a plastic layer.

[0022] The electric field formed between the inner cathode and the tubular electrocatalytic membrane can stimulate the oxygen vacancy particle electrode to generate active species and enhance the oxidation ability.

[0023] The purpose of the insulating layer is to prevent internal short circuit of the device, and the purpose of opening holes in it is to avoid internal open circuit of the device.

[0024] The adapter plays a role in fixing the inner cathode and connecting the anode of the electrocatalytic membrane to the external pipeline, and a passage for the treated wastewater to flow out is provided inside it.

[0025] In a second aspect, the present invention provides an application of the above-mentioned tubular electrocatalytic membrane device filled with particle electrodes in treating saline refractory organic wastewater.

[0026] In a third aspect, the present invention further provides a device for treating saline refractory organic wastewater, and the device uses the above-mentioned tubular electrocatalytic membrane device filled with particle electrodes.

[0027] Further, the device includes a tubular electrocatalytic membrane unit filled with granular electrodes, a cylindrical outer cathode, a cylindrical reactor, a DC power supply, and pipelines. The tubular electrocatalytic membrane unit filled with granular electrodes is placed in the cylindrical reactor. The cylindrical outer cathode is arranged between the tubular electrocatalytic membrane unit filled with granular electrodes and the cylindrical reactor and sleeved outside the tubular electrocatalytic membrane unit filled with granular electrodes. The tubular electrocatalytic membrane unit filled with granular electrodes is connected to the anode of the DC power supply, and the inner cathode of the tubular electrocatalytic membrane unit filled with granular electrodes and the cylindrical outer cathode 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 arranged in the pipeline.

[0028] Further, the pump is a peristaltic pump.

[0029] Further, the distance between the tubular electrocatalytic membrane unit filled with granular 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 unit filled with granular electrodes.

[0030] Further, the current provided by the DC power supply is between 15 - 30 mA / cm 2 between.

[0031] The working process and principle of the above device are as follows: Place the tubular electrocatalytic membrane unit filled with granular electrodes in the cylindrical reactor, sleeve a cylindrical outer cathode outside the tubular electrocatalytic membrane unit filled with granular electrodes, connect the tubular electrocatalytic membrane unit filled with granular electrodes to the anode of the DC power supply, and connect the inner cathode and the outer cathode together to the cathode of the DC power supply. Connect the adapter to the pipeline. Under the action of an applied voltage, treat the saline refractory organic wastewater in the cylindrical reactor to degrade the organic matter in the saline refractory organic wastewater. The saline refractory organic wastewater is sequentially sucked by the peristaltic pump, passes through the tubular electrocatalytic membrane and the granular electrodes, and then flows out through the pipeline and returns to the cylindrical reactor, circulating repeatedly.

[0032] The conductivity of the saline 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.

[0033] Compared with the prior art, the tubular electrocatalytic membrane unit filled with granular electrodes of the present invention has the following advantages: (1) The tubular electrocatalytic membrane reactor filled with particulate electrodes in the present invention has a larger electrochemically reactive area. Under the excitation of the electric field formed between the inner cathode and the electrocatalytic membrane by the particulate electrodes filled in the inner cavity of the tubular electrocatalytic membrane, electrochemical reactions can also occur on the surface of the particulate electrodes to generate active species, degrading the refractory 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 a catalytic effect for degrading organic matter. Through the combined action of the above two aspects, the electrochemically reactive area of the electrode is greatly increased, which is beneficial to improving the reaction rate and reducing energy consumption.

[0034] (2) The introduction of oxygen vacancies in the tubular electrocatalytic membrane reactor filled with particulate electrodes in the present invention can further increase the yield of active species. In the present invention, NaBH4 is used to reduce the particulate electrodes, and this process can introduce oxygen vacancies into the lattice structure. After the introduction of oxygen vacancies, under the excitation of the electric field, the particulate electrodes can generate higher concentrations of active species such as ·OH, thereby improving the degradation rate of organic matter and reducing energy consumption. In addition, the method of introducing oxygen vacancies by NaBH4 reduction also has the characteristics of simple and rapid operation.

[0035] (3) Due to the relatively large electrochemically active area and high yield of active species, the tubular electrocatalytic membrane reactor filled with particulate electrodes in the present invention is particularly suitable for the treatment of high-concentration refractory 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%. Description of the Drawings

[0036] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a schematic structural diagram of a tubular electrocatalytic membrane reactor filled with particulate electrodes; Figure 2 is the X-ray photoelectron spectrum of an oxygen vacancy SnO2-Sb particulate electrode; Figure 3 is a schematic structural diagram of a device for treating saline refractory organic wastewater (the arrow indicates the flow direction of the saline refractory organic wastewater); Figure 4 is the organic matter removal effect of a tubular electrocatalytic membrane reactor filled with particulate electrodes applied to the reverse osmosis concentrate of printing and dyeing wastewater; Figure 5 is a comparison of the organic matter removal effects of Comparative Application Example 1 - Comparative Application Example 5 and 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 for Comparative Application Example 4; T+P OV** +IC is the result for Comparative Application Example 5; T, IC, P, P OV respectively represent the electrocatalytic membrane, inner cathode, particle electrode without oxygen vacancies, and particle electrode with oxygen vacancies. Adding * represents the particle electrode with oxygen vacancies reduced outside the NaBH4 concentration range).

[0037] Reference numerals: 1. Tubular electrocatalytic membrane device filled with particle electrodes; 1-1. Tubular electrocatalytic membrane; 1-2. Oxygen vacancy SnO2-Sb particle electrode; 1-3. Inner cathode; 1-4. Open-cell insulating layer; 1-5. Adapter; 2. Cylindrical outer cathode; 3. Cylindrical reactor; 4. DC power supply; 5. Pipeline; 6. Peristaltic pump. Detailed implementation manners

[0038] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0039] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0040] Embodiment 1 A tubular electrocatalytic membrane device filled with particle electrodes is composed of a tubular electrocatalytic membrane 1-1, an oxygen vacancy SnO2-Sb particle electrode 1-2 filled in the inner cavity of the tubular electrocatalytic membrane 1-1, an inner cathode 1-3 embedded to activate the function of the oxygen vacancy SnO2-Sb particle electrode 1-2, an open-cell insulating layer 1-4 wrapped on the surface of the inner cathode 3, and an adapter 1-5. The tubular electrocatalytic membrane 1-1 is a single-ended cylindrical tubular electrocatalytic membrane, one end of which is closed and the other end is open. An adapter 1-5 is installed at the open end. One end of the inner cathode 1-3 is inserted into the oxygen vacancy SnO2-Sb particle electrode 1-2, and the other end extends outside the tubular electrocatalytic membrane 1-1 through the outside of the adapter.

[0041] The oxygen vacancy SnO2-Sb particle electrode is prepared by the following steps: (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 to paraffin oil is 10:1; (2) Put the mixture into a spherical mold with a diameter of 6 mm and compact it using a tablet press; (3) Take out the compacted particles from the mold and place them in a muffle furnace. Heat them at a heating rate of 2 °C / min to 800 °C and keep them calcined at 800 °C for 6 h; (4) Immerse the calcined particles in a 1 mol / L NaBH4 solution for 10 min of reduction, and finally wash and dry to obtain an oxygen vacancy SnO2-Sb particle electrode.

[0042] The tubular electrocatalytic membrane 1-1 is an electrocatalytic membrane obtained by loading the SnO2-Sb nanocatalyst onto a tubular titanium membrane (SnO2-Sb / Ti tubular electrocatalytic membrane). The pore diameter 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.

[0043] The inner cathode 1-3 is a stainless steel wire with a diameter of 2 mm, and the inner cathode 1-3 is embedded to half of the inner cavity position of the tubular electrocatalytic membrane 1-1.

[0044] The perforated insulating layer 1-4 is a non-woven fabric plastic layer with a thickness less than 1 mm, a perforated diameter between 1 and 3 mm, and a porosity between 60% and 80%.

[0045] The adapter 1-5 functions to fix the inner cathode 1-3 and connect the electrocatalytic membrane anode to the external pipeline.

[0046] Figure 1 It is a schematic structural diagram of a tubular electrocatalytic membrane unit filled with particle electrodes. Figure 2 It is an X-ray photoelectron spectroscopy diagram of the oxygen vacancy SnO2-Sb particle electrode. As Figure 2 can be seen, compared with the SnO2-Sb particle electrode without NaBH4 reduction, the XPS spectrum of the SnO2-Sb particle electrode after NaBH4 reduction shows the characteristic peak of Sn 2+ indicating the generation of oxygen vacancies. At the same time, the characteristic peak of the Sn 3d orbital shifts negatively towards a lower binding energy, indicating that the oxygen vacancies change the surface electronic structure of SnO2-Sb (i.e., the electron density around Sn increases). The above results show that oxygen vacancies are generated in the lattice structure of SnO2-Sb after NaBH4 reduction, that is, an oxygen vacancy SnO2-Sb particle electrode is prepared.

[0047] Example 2 In this example, the tubular electrocatalytic membrane unit filled with particle electrodes 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 pitch is 8:1, heated to 600 °C at a heating rate of 5 °C / min, the calcination temperature is 600 °C, and the concentration of the NaBH4 solution is 0.5 mol / L.

[0048] Example 3 In this embodiment, the tubular electrocatalytic membrane unit filled with particulate electrodes is basically the same as that in Embodiment 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, heated to 700 °C at a heating rate of 1 °C / min, the calcination temperature is 700 °C, and the concentration of the NaBH4 solution is 1.5 mol / L.

[0049] Embodiment 4 In this embodiment, the tubular electrocatalytic membrane unit filled with particulate electrodes is basically the same as that in Embodiment 1, except that: the particulate electrode filled in the tubular electrocatalytic membrane is an oxygen vacancy PbO2 particulate electrode, and the nano-oxide used in the preparation process of the oxygen vacancy PbO2 particulate electrode is nano-lead oxide, and the oxygen vacancy PbO2 particulate electrode is prepared.

[0050] Comparative Example 1 The purpose of Comparative Example 1 is to illustrate that the addition of particulate electrodes and the inner cathode can improve the organic matter degradation effect. In Comparative Example 1, the anode used is the SnO2-Sb / Ti tubular electrocatalytic membrane in Embodiment 1 after removing the particulate electrodes and the inner cathode.

[0051] Comparative Example 2 The purpose of Comparative Example 2 is to further illustrate the importance of particulate electrodes in improving the organic matter removal effect. In Comparative Example 2, the SnO2-Sb oxygen vacancy particulate electrode in Embodiment 1 is removed, and only the inner cathode is retained to construct an electrocatalytic membrane unit.

[0052] Comparative Example 3 The purpose of Comparative Example 3 is to illustrate that the introduction of oxygen vacancies helps to improve the organic matter removal effect. In Comparative Example 3, a particulate electrode without oxygen vacancies (i.e., the SnO2-Sb particulate electrode in Embodiment 1 that has not been treated with NaBH4) is used to replace the SnO2-Sb oxygen vacancy particulate electrode in Embodiment 1 to construct an electrocatalytic membrane unit.

[0053] Comparative Example 4 In this comparative example, the tubular electrocatalytic membrane unit filled with particulate electrodes is basically the same as that in Embodiment 1, except that: the concentration of the NaBH4 solution is 2 mol / L.

[0054] Comparative Example 5 In this comparative example, the tubular electrocatalytic membrane unit filled with particulate electrodes is basically the same as that in Embodiment 1, except that: the concentration of the NaBH4 solution is 0.4 mol / L.

[0055] The present invention also provides a device for treating saline and refractory organic wastewater, such as Figure 3As shown in the figure, the device includes a tubular electrocatalytic membrane unit 1 filled with granular electrodes, a cylindrical outer cathode 2, a cylindrical reactor 3, a DC power supply 4, and a pipeline 5. The tubular electrocatalytic membrane unit 1 filled with granular electrodes is placed in the cylindrical reactor 3. The cylindrical outer cathode 2 is arranged between the tubular electrocatalytic membrane unit 1 filled with granular electrodes and the cylindrical reactor 3 and sleeved outside the tubular electrocatalytic membrane unit 1 filled with granular electrodes. The tubular electrocatalytic membrane unit 1 filled with granular electrodes is connected to the anode of the DC power supply 4, and the inner cathode of the tubular electrocatalytic membrane unit 1 filled with granular 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. A pump is provided in the pipeline 5.

[0056] Application Example 1 The tubular electrocatalytic membrane unit 1 filled with granular electrodes prepared in Example 1 was placed in the cylindrical reactor 3. A cylindrical outer cathode 2 was sleeved outside the tubular electrocatalytic membrane unit 1 filled with granular electrodes. The tubular electrocatalytic membrane 1-1 was connected to the anode of the DC power supply 4, and the inner cathode 1-3 and the cylindrical outer cathode 2 were jointly connected to the cathode of the DC power supply 4. The adapter 1-5 was connected to the pipeline 5, and a peristaltic pump 6 was provided in the pipeline 5. Under the action of an applied voltage, the reverse osmosis concentrate of printing and dyeing wastewater in the cylindrical reactor 3 was treated to degrade the organic matter in the wastewater.

[0057] The conductivity of the reverse osmosis concentrate of printing and dyeing wastewater was 5 mS / cm, and the COD concentration was about 1150 mg / L. The wastewater was sequentially sucked by the peristaltic pump 6 through the tubular electrocatalytic membrane 1-1 and the oxygen vacancy SnO2-Sb granular electrode 1-2 and then flowed out through the pipeline 5 and returned to the cylindrical reactor 3, circulating repeatedly.

[0058] The distance between the tubular electrocatalytic membrane unit 1 filled with granular electrodes and the cylindrical outer cathode 2 was 1 cm, and the height of the cylindrical outer cathode 2 was 2 cm greater than the height of the unit. The current provided by the DC power supply 4 was 20 mA / cm 2 .

[0059] Figure 4 shows the change of COD during the treatment process of the reverse osmosis concentrate of printing and dyeing wastewater. With the extension of the reaction time, the COD concentration showed an obvious downward trend. After 3 h of treatment, the COD concentration changed from 1150 mg / L to 113 mg / L, and the removal rate reached 89.8%. The effluent COD concentration was significantly lower than the limit value (200 mg / L) specified in the "Discharge Standard of Water Pollutants for the Textile Dyeing and Finishing Industry" (GB 4287-2012). The experimental results show that the use of the tubular electrocatalytic membrane unit filled with granular electrodes is effective in removing organic matter from the reverse osmosis concentrate of printing and dyeing wastewater.

[0060] Comparative Application Example 1 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 saline refractory organic wastewater, and it was used to treat the reverse osmosis concentrate of 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 Figure 5 shown. After 3 h of treatment, the COD removal rate was only 64.3%, significantly lower than the removal rate (89.8%, Application Example 1) when the granular electrode was filled, which confirmed that the tubular electrocatalytic membrane device filled with granular electrodes had excellent performance in removing organic matter from wastewater.

[0061] Comparative Application Example 2 The tubular electrocatalytic membrane device prepared in Comparative Example 2 was assembled according to Application Example 1 to obtain a device for treating saline refractory organic wastewater, and it was used to treat the reverse osmosis concentrate of 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 ), lower than 89.8% in Application Example 1, indicating that the addition of the granular electrode helped to improve the removal effect of organic matter.

[0062] Comparative Application Example 3 The tubular electrocatalytic membrane device prepared in Comparative Example 3 was assembled according to Application Example 1 to obtain a device for treating saline refractory organic wastewater, and it was used to treat the reverse osmosis concentrate of 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 ), lower than 89.8% in Application Example 1, indicating that the introduction of oxygen vacancies helped to improve the removal effect of organic matter.

[0063] Comparative Application Example 4 The tubular electrocatalytic membrane device prepared in Comparative Example 4 was assembled according to Application Example 1 to obtain a device for treating saline refractory organic wastewater, and it was used to treat the reverse osmosis concentrate of printing and dyeing wastewater. At the same current density as in Application Example 1, the final COD removal rate was only 77.4%.

[0064] Comparative Application Example 5 The tubular electrocatalytic membrane device prepared in Comparative Example 5 was assembled according to Application Example 1 to obtain a device for treating saline refractory organic wastewater, and it was used to treat the reverse osmosis concentrate of printing and dyeing wastewater. At the same current density as in Application Example 1, the final COD removal rate was only 81.5%.

[0065] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope 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 single-end-through cylindrical tubular electrocatalytic membrane, one end of which is closed and the other end is open; a adapter is installed at the open end of the tubular electrocatalytic membrane, and an inner cathode is arranged on the adapter. One end of the inner cathode is inserted into the oxygen vacancy particle electrode, and the other end extends outside the tubular electrocatalytic membrane through the outside of the adapter. The surface of the inner cathode is wrapped with an insulating layer; the oxygen vacancy particle electrode is an antimony tin oxide with oxygen vacancies or a lead oxide with oxygen vacancies.

2. The tubular electrocatalytic membrane unit filled with particulate electrodes according to claim 1, wherein: The oxygen vacancy particle electrode is prepared by the following steps: (1) Take nano-oxide powder with a particle size of 20-40 nm, mix it evenly with a pore former and a binder to obtain a mixture; (2) Put the mixture into a spherical mold with a diameter of 5-7 mm and compact it with a tablet press; (3) Take out the compacted particles from the mold and place them in a muffle furnace, heat them to 600-800 °C, and keep them calcined at a constant temperature for 6-8 h; (4) Immerse the calcined particles in a NaBH4 solution for reduction for 10-20 min, and finally wash and dry them to obtain the oxygen vacancy particle electrode; The mass ratio of the nano-oxide powder to the pore former 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 0.5-1.5 mol / L; and / or The nano-oxide powder is one or a mixture of two of nano-antimony tin oxide powder and nano-lead oxide particles; and / or The pore former is one or a mixture of more than two of (NH4)2CO3, NH4HCO3, and polyvinyl butyral; and / or The binder is one or a mixture of more than two of paraffin oil, coal tar pitch, and carboxymethyl cellulose.

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

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

5. The tubular electrocatalytic membrane unit filled with particulate electrodes according to claim 1, wherein: The insulating layer has a thickness less than 1 mm.

6. The tubular electrocatalytic membrane unit filled with particulate electrodes according to claim 1, characterized in that: A number of through holes are opened on the surface of the insulating layer, the pore diameter of the through holes is 1-3 mm, and the porosity is between 60% and 80%.

7. Application of the tubular electrocatalytic membrane device filled with the particle electrode according to any one of claims 1-6 in treating saline refractory organic wastewater.

8. A device for treating refractory organic wastewater containing salt, characterized in that: Apply the tubular electrocatalytic membrane device filled with the particle electrode according to any one of claims 1-6.

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

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

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