Electrochemical double membrane reactor and wastewater treatment method based on electrochemical double membrane reactor

Abstract

The application provides an electrochemical double membrane reactor and a wastewater treatment method based on the electrochemical double membrane reactor, and belongs to the field of membrane separation and electrochemical advanced oxidation technology. The wastewater treatment method based on the electrochemical double membrane reactor is coupled with membrane separation and electrochemical advanced oxidation technology, a first conductive microporous membrane is used as an anode membrane, a second conductive microporous membrane is used as a cathode membrane, the anode membrane generates hydroxyl radicals by electrolysis of water, the cathode membrane generates H2O2 by electro-reduction of oxygen and further converts the H2O2 into hydroxyl radicals through a Fenton catalyst, and the two cooperate to generate singlet oxygen, so that removal of refractory organic matter and / or heavy metals in wastewater is realized. The electrochemical double membrane reactor can make multiple active substances act together in the electrochemical process, removal of refractory organic matter and heavy metals in wastewater is realized, and the electrochemical double membrane reactor can be widely applied to treatment and reuse of industrial wastewater, landfill leachate and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of membrane separation and electrochemical advanced oxidation technology, and particularly relates to an electrochemical double-membrane reactor and a wastewater treatment method based on the electrochemical double-membrane reactor. BACKGROUND

[0002] In recent years, electrochemical membrane technology based on electrochemical advanced oxidation process is considered as one of the most promising candidates in the next generation of water purification technology. It can in-situ decompose wastewater pollutants, and is expected to surpass the traditional membrane filtration technology which relies on physical interception and transfer of pollutants. And electrochemical advanced oxidation endows electrochemical membrane with multiple functions, such as electro-catalytic and electro-Fenton degradation, electro-disinfection, anti-fouling, etc., which has great application potential in the fields of environment, energy, medical treatment, etc. Although the membrane filtration process improves the electrochemical efficiency by strengthening mass transfer and limiting effect, the efficiency and energy consumption are still the key problems limiting the development of electrochemical membrane technology.

[0003] The electrochemical membrane reactor is mainly composed of an anode and a cathode. At present, most of the related researches focus on the half-cell reaction of taking a single electro-catalytic membrane as the anode or taking a single electro-Fenton membrane as the cathode (with a relatively inert counter electrode). CN101597096A discloses an electro-catalytic membrane reactor device, which takes an electro-catalytic composite membrane as the anode and a stainless steel mesh as the cathode, and constructs an electro-catalytic membrane reactor device for coupling membrane separation technology and electro-catalytic technology for wastewater treatment. The pollutants can be oxidized and decomposed by the hydroxyl radicals generated by electro-catalysis, which can effectively solve the problem of membrane fouling and realize the self-cleaning function of the membrane. The reactor can be used for industrial wastewater treatment and reuse, such as oil-containing wastewater, dye wastewater, papermaking wastewater, etc. CN103193297A discloses a sewage treatment method coupling organic membrane and electro-Fenton catalytic technology, which takes a conductive polymer modified organic fabric membrane as the cathode and a stainless steel mesh as the anode, and constructs an electro-Fenton membrane system combining organic membrane separation and electro-Fenton catalytic technology. Hydrogen peroxide is generated by the cathodic reduction of oxygen, and hydroxyl radicals are further generated under the action of the Fenton catalyst, which can effectively reduce the pollution and load of the membrane assembly. Membrane filtration can strengthen the effective contact and reaction of pollutants with the membrane electrode, and is beneficial to the removal of large particles of pollutants which are not easy to degrade.

[0004] However, in the process of treating wastewater by the existing anode membrane reactor and cathode membrane reactor, only a single anode or a single cathode works, which causes the waste of electric energy of the auxiliary counter electrode (such as a stainless steel mesh), greatly limiting the development of electrochemical membrane technology. In order to solve this problem, it is imperative to couple the cathode and the anode to degrade pollutants, which not only can improve the degradation efficiency of the reactor, but also can reduce the energy consumption. SUMMARY

[0005] The application provides an electrochemical double membrane reactor and a wastewater treatment method based on the electrochemical double membrane reactor, which can make multiple active substances jointly act in an electrochemical process, removes refractory organic matter and heavy metals in wastewater, and can be widely applied to treatment and reuse of industrial wastewater, landfill leachate and the like.

[0006] In order to achieve the above-mentioned purpose, the application provides a wastewater treatment method based on an electrochemical double membrane reactor, which couples membrane separation and electrochemical advanced oxidation technology, uses a first conductive microporous membrane as an anode membrane and a second conductive microporous membrane as a cathode membrane, generates hydroxyl radicals by electrolysis of water through the anode membrane, generates H2O2 by electro-reduction of oxygen through the cathode membrane, and further converts the H2O2 into hydroxyl radicals through a Fenton catalyst, so that the removal of refractory organic matter and / or heavy metals in wastewater is realized.

[0007] Specifically, the first conductive microporous membrane generates hydroxyl radicals (·OH groups) with strong oxidation ability by catalytic decomposition of H2O through a catalyst under the action of an anode electric field, and oxidizes and decomposes pollutants in wastewater; the second conductive microporous membrane generates H2O2 by electro-reduction of O2 under the action of a cathode electric field, and then catalytically decomposes the H2O2 into hydroxyl radicals through a Fenton catalyst (Fe 2+ or Fe II ), which jointly oxidize and decompose the pollutants in wastewater. In addition, the anode and cathode membranes have a synergistic catalytic effect, specifically, the cathode can electro-reduce O2 to generate superoxide anion (O2· - groups), which is converted into singlet oxygen radicals (O2 1 ) under the action of the anode, and the strong oxidation ability of O2 1 can also oxidize and decompose the pollutants in wastewater. The reactor improves the wastewater degradation efficiency and reduces energy consumption by the joint action of multiple radicals generated by the anode and cathode conductive microporous membranes and the synergistic action of the two electrodes.

[0008] As a preferred, the first conductive microporous membrane and the second conductive microporous membrane are selected from one of carbon membranes and metal titanium membranes, which are prepared by loading metals, metal oxides or inorganic heteroatoms.

[0009] As a preferred, the first conductive microporous membrane is selected from one of activated carbon-based carbon membranes loaded with TiO2 and metal titanium membranes loaded with TiO2, and the second conductive microporous membrane is selected from one of activated carbon-based carbon membranes and activated carbon-based carbon membranes loaded with Fe 0 / FeOx.

[0010] As a preferred, the wastewater is introduced into the electrochemical double membrane reactor, the first conductive microporous membrane is used as an anode membrane, the second conductive microporous membrane is used as a cathode membrane, and the membrane filtration flux of the anode membrane and the cathode membrane is adjusted to treat the wastewater.

[0011] As preferred, the membrane filtration flux of the anode membrane and the cathode membrane is adjusted by adjusting the pump speed of the peristaltic pump, and the membrane filtration flux is 10-50 L / m 2 h;

[0012] The effective volume of the anode membrane and the cathode membrane ranges from 20*20*1 mm to 400*150*10 mm 3 , the electrode spacing ranges from 15 mm to 30 mm, the electrolyte is 7.1-14.2 g / L sodium sulfate, the oxygen exposure rate ranges from 100 mL / min to 400 mL / min, and the Fenton catalyst is 0.02-0.1 mmol / L ferrous sulfate or ferrous chloride.

[0013] As preferred, the electrochemical double membrane reactor comprises an electrolysis device, which is formed by placing a first conductive microporous membrane in the anode membrane chamber, placing a second conductive microporous membrane in the cathode membrane chamber, and connecting the two chambers with an adjustable direct current stabilized power supply through connecting wires.

[0014] As preferred, the operating voltage adjustment range of the adjustable direct current stabilized power supply is 1-3 V, and the current is 1-50 mA.

[0015] As preferred, the wastewater is selected from one of phenol-containing, ammonia nitrogen-containing, oil-containing, or dye-containing industrial wastewater, and landfill leachate.

[0016] The application also provides an electrochemical double membrane reactor, which is composed of a blind plate, an anode permeate cavity, an anode permeate outlet, an anode membrane chamber, a feed cavity, a feed inlet, a cathode membrane chamber, a cathode permeate cavity, and a cathode permeate outlet.

[0017] The first conductive microporous membrane is arranged in the anode membrane chamber, and the second conductive microporous membrane is arranged in the cathode membrane chamber.

[0018] The anode permeate outlet and the cathode permeate outlet are connected with respective peristaltic pumps through pipelines, and the peristaltic pumps continuously provide negative pressure to make the feed liquid in the feed tank permeate through the first conductive microporous membrane and the second conductive microporous membrane from the feed cavity side to the anode permeate tank and the cathode permeate tank side, respectively.

[0019] As preferred, the anode permeate outlet and the cathode permeate outlet are also connected with the anode permeate tank and the cathode permeate tank through pipelines, respectively, and a vacuum gauge is arranged on each pipeline.

[0020] Compared with the prior art, the application has the following advantages and positive effects:

[0021] The electrochemical dual-membrane reactor provided by this invention generates hydroxyl radicals through water electrolysis at the anolyte; the H2O2 generated by the electroreduction of oxygen at the cathode is further converted into hydroxyl radicals under the action of a Fenton catalyst; and the synergistic catalytic action of the anode and cathode membranes produces singlet oxygen. The combined action of multiple active substances achieves the synergistic removal of recalcitrant organic matter in wastewater, that is, its degradation into easily biodegradable small molecules or its mineralization into carbon dioxide and water. It can also be used for the oxidation or removal of heavy metals. This reactor device is diaphragm-free and has the advantages of convenient operation, high efficiency, and low energy consumption, and can be widely used in the treatment and reuse of industrial wastewater and landfill leachate. Attached Figure Description

[0022] Figure 1 A diagram of an electrochemical dual-membrane reactor device provided in an embodiment of the present invention;

[0023] Reference numerals in the figures: 1. First conductive microporous membrane; 2. Second conductive microporous membrane; 3. Adjustable DC regulated power supply; 4. Power connection wire; 5. Peristaltic pump; 6. Vacuum gauge; 7. Feed tank; 8. Anode permeate tank; 9. Cathode permeate tank; 10. Blind plate; 11. Anode permeate chamber; 12. Anode permeate outlet; 13. Anode membrane chamber; 14. Feed chamber; 15. Feed inlet; 16. Cathode membrane chamber; 17. Cathode permeate chamber; 18. Cathode permeate outlet.

[0024] Figure 2 The degradation rates of phenol at different concentrations are shown in Example 4 of this invention by three electrochemical membrane reactors: an electrochemical dual-membrane reactor, an electrocatalytic membrane reactor, and an electro-Fenton membrane reactor. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] like Figure 1 As shown, the electrochemical dual-membrane reactor consists of a blind plate (10), an anolyte chamber (11), an anolyte outlet (12), an anolyte membrane chamber (13), a feed chamber (14), a feed inlet (15), a cathode membrane chamber (16), a cathode permeate chamber (17), and a cathode permeate outlet (18).

[0028] The anode membrane chamber (14) is internally provided with a first conductive microporous membrane (1), the cathode membrane chamber (17) is internally provided with a second conductive microporous membrane (2), the cathode membrane chamber (17) and the anode membrane chamber (14) are respectively connected with an adjustable direct current stabilized power supply (3) through connecting wires (4), and an electrolysis device is formed.

[0029] The anode permeate liquid outlet (12) and the cathode permeate liquid outlet (18) are connected with respective peristaltic pumps (5) through pipelines, negative pressure is continuously provided through the peristaltic pumps (5), and the feed liquid in the feed liquid tank (7) is permeated through the first conductive microporous membrane (1) and the second conductive microporous membrane (2) from the side of the feed cavity (14) to the sides of the anode permeate liquid tank (8) and the cathode permeate liquid tank (9) respectively. Moreover, the anode permeate liquid outlet (12) and the cathode permeate liquid outlet (18) are also connected with the anode permeate liquid tank (8) and the cathode permeate liquid tank (9) through pipelines respectively, and vacuum gauges (6) are arranged on the pipelines respectively.

[0030] The feed liquid of the electrochemical double membrane reactor is 1L of 5mM simulated phenol-containing wastewater, the conductive microporous membrane (TiO2-loaded activated carbon-based carbon membrane) is used as the anode, the activated carbon-based carbon membrane is used as the cathode, the effective volume of the anode and the cathode is 37*37*4mm 3 , the operating voltage is 2.1V, the current is 11mA, the electrode spacing is 2.2cm, the pH value is 3, the electrolyte concentration is 14.2g / L Na2SO4, the Fenton catalyst Fe2SO4 concentration is 0.02mmol / L, the oxygen exposure rate is 100mL / min, and the Figure 1 connecting device is adjusted to make the filtration fluxes of the anode membrane and the cathode membrane both be 10.1L / m 2 h.

[0031] The experimental results show that the degradation rate of the phenol-containing wastewater is 89.2%, and the COD degradation rate is 78.1%.

[0032] As a comparison, an anode membrane reactor is set: the anode is a conductive microporous membrane (TiO2-loaded activated carbon-based carbon membrane), the cathode is a stainless steel mesh, and other conditions are consistent with the double membrane reactor provided in Example 1.

[0033] It is found that the treatment efficiency of the double membrane reactor provided in Example 1 is improved by 61% compared with the traditional anode membrane reactor with the conductive microporous membrane (TiO2-loaded activated carbon-based carbon membrane) as the anode and the stainless steel mesh as the cathode, and the energy consumption is reduced by 28.3%.

[0034] Example 2

[0035] The feed liquid of the electrochemical double membrane reactor is 0.5L of 1g / L simulated ammonia-nitrogen wastewater.

[0036] Using a conductive microporous membrane (an activated carbon-based membrane supported on TiO2) as the anode, and a conductive microporous membrane (supported on Fe) as the cathode... 0 The cathode is an activated carbon-based film containing FeOx, and the effective volume of the anode and cathode is 37×37×5mm. 3 Operating voltage 1.6V, current 8mA, electrode spacing 2.5cm, pH value 3, electrolyte concentration 14.2g / LNa2SO4, aeration rate 100mL / min, according to... Figure 1 Connect the device and adjust the pump speed to ensure that the filtration flux of both the anode and cathode membranes is 20 L / m. 2 h.

[0037] Experimental results: The degradation rate of oily wastewater was 95.6%, and the COD degradation rate was 85.1%.

[0038] In contrast, a cathode membrane reactor was set up: the anode was a platinum sheet, and the cathode was a conductive microporous membrane (loaded with Fe). 0 The activated carbon-based carbon membrane (FeOx) was used, and other conditions were the same as those for the electrochemical dual-membrane reactor provided in Example 2.

[0039] The results showed that the treatment efficiency of the dual-membrane reactor provided in Example 2 was higher than that of the reactor using a platinum sheet as the anode and a conductive microporous membrane (loaded with Fe). 0 The traditional cathode membrane reactor with FeOx activated carbon-based carbon membrane as the cathode improved efficiency by 47% and reduced energy consumption by 16.6%.

[0040] Example 3

[0041] The feed liquid for the electrochemical dual-membrane reactor is 0.25L of simulated dye wastewater containing 200mg / L methylene blue.

[0042] A conductive microporous membrane (a titanium film loaded with TiO2) is used as the anode, with an effective anode volume of 37×37×2mm. 3 ; with conductive microporous membrane (loaded with Fe) 0 The cathode is an activated carbon-based film containing FeOx, and the effective cathode volume is 37×37×5mm. 3 Operating voltage 2V, electrode spacing 2cm, current 5mA, pH value 3, electrolyte concentration 7.1g / L Na2SO4, aeration rate 100mL / min, according to... Figure 1 Connect the device and adjust the pump speed to ensure that the filtration flux of both the anode and cathode membranes is 20 L / m. 2 h.

[0043] Experimental results: The color removal rate of methylene blue wastewater reached 99.9%, and the removal rate of phenothiazine heterocycles reached 97.0%.

[0044] As a comparison, an anode membrane reactor was set up: the anode was a conductive microporous membrane (a metal titanium membrane loaded with TiO2), the cathode was a stainless steel mesh, and the other conditions were consistent with the double membrane reactor provided in Example 3.

[0045] It was found that the treatment efficiency of the double membrane reactor provided in Example 3 was improved by 95% compared to the conventional anode membrane reactor with a conductive microporous membrane (a metal titanium membrane loaded with TiO2) as the anode and a stainless steel mesh as the cathode, and the energy consumption was reduced by 47.2%.

[0046] Example 4

[0047] The feed liquid of the electrochemical double membrane reactor was 1L of 2mM, 5mM, and 10mM simulated phenol-containing wastewater, respectively.

[0048] The double membrane reactor used a conductive microporous membrane (an activated carbon-based carbon membrane loaded with TiO2) as the anode and a conductive microporous membrane (an activated carbon-based carbon membrane loaded with Fe 0 / FeOx) as the cathode, the effective volume of the anode and cathode was 47x197x8mm 3 , the operating voltage was 2.1V, the current was 150mA, the inter-electrode distance was 2.2cm, the pH value was 3, the electrolyte concentration was 14.2g / L Na2SO4, the oxygen exposure rate was 100mL / min, and the connection device was adjusted to make the filtration flux of the anode and cathode membrane be 50L / m Figure 1 h. 2

[0049] The anode membrane reactor was set up: the anode was a conductive microporous membrane (an activated carbon-based carbon membrane loaded with TiO2), the cathode was a stainless steel mesh, and the other conditions were consistent with the double membrane reactor provided in Example 4.

[0050] The cathode membrane reactor was set up: the anode was a stainless steel mesh, the cathode was a conductive microporous membrane (an activated carbon-based carbon membrane loaded with Fe 0 / FeOx), and the other conditions were consistent with the electrochemical double membrane reactor provided in Example 4.

[0051] The COD degradation rates and energy consumptions of the three electrochemical membrane reactors for different concentrations of phenol were compared, and the results are shown in Figure 2 . The results show that under the same conditions, for the same volume of phenol with different concentrations, the phenol degradation rate of the double membrane reactor is improved by 53.1-67.8% compared to the single-stage working anode membrane reactor and cathode membrane reactor, and the energy consumption is reduced by 20.9-26.8%.​

Claims

1. A method for wastewater treatment based on an electrochemical double membrane reactor, characterized in that, The electrochemical double membrane reactor couples membrane separation and electrochemical advanced oxidation technology, uses a first conductive microporous membrane as an anode membrane and a second conductive microporous membrane as a cathode membrane, generates hydroxyl radicals by electrolysis of water through the anode membrane, generates H2O2 by electro-reduction of oxygen through the cathode membrane and further converts the H2O2 into hydroxyl radicals through a Fenton catalyst, and realizes removal of refractory organic matter and / or heavy metals in wastewater through synergistic catalysis of the hydroxyl radicals and the singlet oxygen; The first conductive microporous membrane is a TiO2-loaded activated carbon-based carbon membrane, and the second conductive microporous membrane is a Fe 0 / FeOx-loaded activated carbon-based carbon membrane. The effective volume of the anode film and the cathode film ranges from 20 x 20 x 1 to 400 x 150 x 10 mm 3 .

2. The wastewater treatment method according to claim 1, characterized by, The wastewater is introduced into the electrochemical double membrane reactor, a first conductive microporous membrane is used as an anode membrane and a second conductive microporous membrane is used as a cathode membrane, and the membrane filtration fluxes of the anode membrane and the cathode membrane are adjusted to treat the wastewater.

3. The wastewater treatment method according to claim 2, characterized by, The membrane filtration flux of the anode membrane and the cathode membrane is adjusted by adjusting the pump speed of the peristaltic pump, and the membrane filtration flux is 10-50 L / m 2 h; The electrode spacing ranges from 15 mm to 30 mm, the electrolyte is 7.1-14.2 g / L sodium sulfate, the oxygen exposure rate ranges from 100 mL / min to 400 mL / min, and the Fenton catalyst is 0.02-0.1 mmol / L ferrous sulfate or ferrous chloride.

4. The wastewater treatment method according to claim 2, characterized by, The electrochemical double membrane reactor comprises an electrolysis device, which is formed by connecting the first conductive microporous membrane to the anode membrane chamber, connecting the second conductive microporous membrane to the cathode membrane chamber, and connecting the two chambers to an adjustable direct current stabilized power supply through connecting wires.

5. The wastewater treatment method according to claim 4, characterized by, The operating voltage of the adjustable direct current stabilized power supply ranges from 1 V to 3 V, and the current ranges from 1 mA to 150 mA.

6. The method of treating wastewater according to any one of claims 1-5, wherein, The wastewater is selected from one of industrial wastewater containing phenol, ammonia nitrogen, oil or dye, and landfill leachate.

7. An electrochemical double membrane reactor for use in the wastewater treatment process according to any one of claims 1 to 6, characterized in that, The blind plate, the anode permeate cavity, the anode permeate outlet, the anode membrane chamber, the feed cavity, the feed inlet, the cathode membrane chamber, the cathode permeate cavity, and the cathode permeate outlet are connected to each other; The first conductive microporous membrane is arranged in the anode membrane chamber, the second conductive microporous membrane is arranged in the cathode membrane chamber, and the cathode membrane chamber and the anode membrane chamber are connected to an adjustable direct current stabilized power supply through connecting wires to form an electrolysis device; The anode permeate outlet and the cathode permeate outlet are connected to respective peristaltic pumps through pipelines, and the peristaltic pumps provide negative pressure to make the feed liquid in the feed cavity permeate through the first conductive microporous membrane and the second conductive microporous membrane from the feed cavity side to the anode permeate tank and the cathode permeate tank side, respectively.

8. The electrochemical dual membrane reactor of claim 7, wherein, The anode permeate outlet and the cathode permeate outlet are also connected to the anode permeate tank and the cathode permeate tank through pipelines, respectively, and a vacuum gauge is arranged on each pipeline.

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