CN108585123A - A filter type electrochemical reactor, water treatment device and water treatment method - Google Patents

Abstract

The invention discloses a filtering type electrochemical reactor, a water treatment device and a water treatment method, wherein the filtering type electrochemical reactor comprises a water distribution pipe, a plurality of layers of tubular porous electrodes and a tubular reactor wall which are sequentially nested from inside to outside, openings at two ends of the tubular porous electrodes and the tubular reactor wall are packaged by adopting a sealing structure, the water distribution pipe penetrates through the sealing structure, the water distribution pipe is provided with a water inlet, and a cavity formed by the tubular porous electrodes at the outermost layer and the tubular reactor wall is provided with a water outlet; the water distribution pipe and the tubular reactor wall are made of conductive materials, and the water distribution pipe and the tubular reactor wall are arranged as cathodes; the tubular porous electrodes are alternately arranged into anodes and cathodes from inside to outside; the porosity of the tubular porous electrode is greater than or equal to 45%. After the organic wastewater passes through the tubular porous electrode, the pollutants are filtered and electrochemically oxidized and degraded in one step, the sewage purification time is short, and the efficiency is high; moreover, the porous electrode can improve the turbulent fluctuation of water flow and the efficiency of electrochemical oxidation reaction, so that the filtering type electrochemical reactor has the characteristics of high electrochemical oxidation efficiency and low energy consumption.

Description

A filter type electrochemical reactor, water treatment device and water treatment method

technical field

The invention relates to the technical field of sewage treatment, more specifically, to a filter type electrochemical reactor, a water treatment device and a water treatment method.

Background technique

With the rapid development of my country's economy, the types and quantities of organic pollutants entering the water environment are increasing, and the problem of water environment pollution caused by organic waste is becoming more and more serious. For example, halogenated organic compounds (such as chloroform, perfluorinated compounds, etc.) are often used as solvents and surfactants in human production and life, and have been continuously detected in various environmental media in recent years. Most halogenated organic compounds are highly persistent, refractory and highly toxic in the environment. Studies have shown that long-term exposure to low doses of halogenated organic compounds can also cause long-term damage to aquatic organisms. Therefore, exploring efficient treatment technologies for refractory organic wastewater is one of the hotspots in the field of environmental research in recent years.

In recent years, electrochemical oxidation has been widely studied in the treatment of organic wastewater. Its mechanism is mainly to use high-efficiency anodes to directly oxidize organic matter, or to use active oxygen species (such as, HO∙, O ₂ ‾) generated on the electrode surface to indirect oxidation organic matter. Electrochemical oxidation technology does not require the addition of oxidants, has the advantages of mild reaction conditions, simple equipment, and convenient use. It has become one of the effective means to deal with toxic organic substances in the environmental field.

However, the efficiency of the existing electro-oxidation reaction system is low, which is mainly due to the low effective utilization efficiency of electrodes and the slow mass transfer rate between pollutants and electrodes, which greatly increases the cost of water treatment and hinders the large-scale application of this technology. The key to the practical application of electrochemical oxidation technology is to improve the efficiency of electrochemical oxidation and save energy consumption. At present, the existing domestic patents aimed at improving the efficiency of electrochemical oxidation are mainly to modify electrode materials, such as boron-doped diamond electrodes, rare earth-doped oxide electrodes, titanium-based polyvinylidene fluoride-doped lead dioxide anodes, these Most of the electrodes are complicated to prepare, high in cost, and difficult to be applied in the actual wastewater treatment. Although there are also patent reports to improve the electrochemical device, they only change the form of the reaction device to strengthen the water flow turbulence, or simply assemble the combined equipment of electroflocculation/electric floatation and electrooxidation, so as to strengthen the removal effect of the device on pollutants. The steps are complicated and the efficiency is low.

Existing electrochemical reactors and water treatment devices have the problems of low electrochemical oxidation efficiency and high energy consumption. It is urgent to design electrochemical reactors and water treatment devices with higher electrochemical oxidation efficiency and lower energy consumption.

Contents of the invention

In order to overcome the above-mentioned defects in the prior art, the present invention provides a filtering electrochemical reactor capable of simultaneously performing multi-stage filtering and electrochemical oxidation to remove organic pollutants.

Another object of the present invention is to provide an electrochemical water treatment device.

Another object of the present invention is to provide an electrochemical water treatment method.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A filter type electrochemical reactor, comprising water distribution pipes nested sequentially from the inside to the outside, multi-layer tubular porous electrodes, and tubular reactor walls, the openings at both ends of the tubular porous electrodes and the tubular reactor walls are packaged in a sealed structure , the water distribution pipe passes through the sealing structure, the water distribution pipe is provided with a water inlet, and the cavity formed by the outermost tubular porous electrode and the tubular reactor wall is provided with a water outlet;

The water distribution pipe and the tubular reactor wall are made of conductive materials, and the water distribution pipe and the tubular reactor wall are set as cathodes; the multi-layer tubular porous electrodes are alternately arranged as anodes and cathodes from the inside to the outside; the tubular porous The porosity of the electrode is greater than or equal to 45%.

In the filtering electrochemical reactor, the tubular porous electrode not only functions as an electrochemical oxidation unit, but also as a filter unit. The electrochemical oxidation unit and the filter unit are organically combined. After the wastewater passes through the tubular porous electrode, one step Realize filtration and electrochemical oxidation to degrade pollutants, shorten sewage purification time and high efficiency; moreover, using a booster pump, porous electrodes can improve water flow turbulence, reduce the thickness of electrochemical oxidation edge layer, enhance mass transfer efficiency, and improve electrochemical oxidation The reaction efficiency makes the filter type electrochemical reactor of the present invention have the characteristics of high electrochemical oxidation efficiency and low energy consumption.

In addition, the filter-type electrochemical reactor is easy to operate, green and safe, and can realize continuous and dynamic treatment of sewage without aeration and addition of chemical reagents.

In filter electrochemical reactors, the porosity of tubular porous electrodes must be greater than or equal to 45%. The lower the porosity, the higher the pressure required to pass through the porous electrodes. If the porosity is lower than 45%, water will pass through. As a result, the pressure in the electrochemical reactor increases sharply, and the sealing structure of the electrochemical reactor is easily broken after a long time of use.

Preferably, the porosity of the tubular porous electrode is 45%-80%.

When the waste water flows through the surface of the electrode, the higher the porosity, the easier the waste water passes through, the less time the organic matter is in contact with the electrode, and the shorter the corresponding sewage treatment time. Therefore, the preferred selection of the tubular porous electrode has a porosity of 45. %~80%.

More preferably, the porosity of the tubular porous electrode is 45%-60%.

Preferably, the filtration accuracy of the tubular porous electrode increases sequentially from the inside to the outside.

Organic wastewater enters from the water inlet of the water distribution pipe, passes through the water distribution pipe and multi-layer tubular porous electrodes successively from the inside to the outside, and is filtered step by step through the multi-layer tubular porous electrodes to realize electrochemical oxidation to remove organic pollutants and realize multi-stage filtration at the same time.

Preferably, the filtration accuracy of the tubular porous electrode is 0.02-100 μm.

In the step-by-step filtration of organic wastewater, the higher the filtration accuracy, the higher the pressure required for the wastewater to pass through the porous electrode. When the filtration accuracy of the reactor is less than 0.02 μm, the pressure in the reactor increases sharply, which is not conducive to the long-term operation of the reactor. Time to use; when the filtration accuracy is greater than 100 μm, it will cause the organic matter in the wastewater to easily pass through the porous electrode, greatly reducing the filtration and electro-oxidation effects.

Preferably, the filter-type electrochemical reactor includes three layers of tubular porous electrodes, the first tubular porous electrode, the second tubular porous electrode, and the third tubular porous electrode in sequence from inside to outside. The first tubular porous electrode and the third tubular porous electrode are anodes, and the second tubular porous electrode is a cathode.

Preferably, the tubular porous electrode set as the anode is a titanium-based oxide electrode or a conductive ceramic electrode with a high oxygen evolution potential. The use of titanium-based oxide electrodes or conductive ceramic electrodes with high oxygen evolution potential can inhibit the occurrence of oxygen evolution side reactions and improve the electrochemical oxidation efficiency.

Preferably, the titanium-based oxide electrode includes a titanium-based tin antimony oxide electrode, a titanium-based lead dioxide electrode, and a titanium-based iridium dioxide electrode.

Preferably, the tubular porous electrode configured as a cathode is made of the conductive material.

Preferably, the number of electrodes configured as cathodes is one more than the number of electrodes configured as anodes. The number of the cathode is one more than that of the anode, which can improve the utilization rate of the anode.

Preferably, the part of the water distribution pipe located inside the filtering electrochemical reactor is provided with through holes.

Preferably, the diameter of the through hole is 0.5-2.0mm.

Preferably, the conductive material includes stainless steel, copper, titanium. Stainless steel, copper, and titanium have good electrical conductivity and are suitable for preparing cathodes for electrochemical reactors. The water distribution pipe, the tubular porous electrode and the tubular reactor wall set as the cathode can all be made of stainless steel, copper or titanium.

Preferably, the sealing structure is a plexiglass flange.

Both the openings at both ends of the tubular reactor wall and the tubular porous electrode are encapsulated with plexiglass flanges. The plexiglass flange is locked by bolts.

Preferably, the distance between the tubular porous electrode adjacent to the water distribution pipe and the water distribution pipe is 0.5-2.5 cm.

Preferably, the distance between the tubular porous electrodes is 0.5-2.5 cm.

Preferably, the distance between the tubular porous electrode adjacent to the tubular reactor wall and the tubular reactor wall is 0.5-2.5 cm.

An electrochemical water treatment device includes a direct current power supply, a booster pump, and the filter type electrochemical reactor. A DC power supply supplies power to the filtered electrochemical reactor. The booster pump can provide power for the organic wastewater entering the electrochemical water treatment device, and cooperate with the tubular porous electrode to further improve the water flow turbulence, reduce the thickness of the electrochemical oxidation boundary layer, enhance the mass transfer efficiency, and improve the electrochemical oxidation reaction efficiency .

Preferably, the electrochemical water treatment device further includes a water inlet pipe connected to the water distribution pipe.

Preferably, the electrochemical water treatment device further includes a water outlet pipe connected to the water outlet of the filtering electrochemical reactor.

Preferably, the electrochemical water treatment device further includes a flow meter connected to the water inlet pipe or the water outlet pipe.

Preferably, the electrochemical water treatment device further includes a water inlet pressure gauge, and the water inlet pressure gauge is arranged in the pipeline between the booster pump and the filtering electrochemical reactor.

Preferably, the electrochemical water treatment device further includes a water outlet pressure gauge connected to the water outlet pipe.

Preferably, the electrochemical water treatment device further includes a water inlet tank connected to the water inlet pipe.

Preferably, the electrochemical water treatment device includes the filter type electrochemical reactor, a DC power supply, a water inlet tank, a booster pump, a flow meter, an inlet water pressure gauge and an outlet water pressure gauge, and the water outlet of the water inlet tank, The booster pump, flow meter, water inlet pressure gauge, and the water inlet of the filter electrochemical reactor are connected through pipelines in sequence, and the water outlet of the filter type electrochemical reactor, water outlet pressure gauge, and water inlet of the water inlet tank are sequentially connected through the pipeline connect.

A method for electrochemical water treatment, comprising the steps of:

S1. Adding supporting electrolytes to organic wastewater;

S2. Connect the above-mentioned filter electrochemical reactor to a DC power supply, the pressure difference between the inlet water and the outlet water of the filter electrochemical reactor is 0.4~10.5MPa, and the organic wastewater of S1. is passed into the water distribution pipe, and the organic wastewater After being treated, it flows out from the water outlet.

The pressure difference is closely related to the porosity of the tubular porous electrode and the filtration accuracy. After connecting with a tube, the reactor is a relatively sealed device. Too small pressure makes water diffusion slow, poor mass transfer, and is not conducive to degradation; too large pressure It shows that the pressure in the reactor is too high, which is not conducive to long-term use.

Preferably, the supporting electrolyte is NaClO ₄ , NaCl, NaNO ₃ or Na ₂ SO ₄ .

Preferably, the concentration of the supporting electrolyte is 10-80 mM.

Preferably, the current density is 2-30 mA/cm ² .

Compared with prior art, the beneficial effect of the present invention is:

In the filtering electrochemical reactor of the present invention, the tubular porous electrode not only has the function of electrochemical oxidation unit, but also has the effect of filtering unit, and the electrochemical oxidation unit and filtering unit are organically combined, and the waste water passes through the tubular porous electrode. , to achieve filtration and electrochemical oxidation to degrade pollutants in one step, and the sewage purification time is short and the efficiency is high; moreover, the porous electrode can improve the water flow turbulence, reduce the thickness of the electrochemical oxidation edge layer, enhance the mass transfer efficiency, and improve the electrochemical oxidation reaction efficiency. The filter type electrochemical reactor of the present invention has the characteristics of high electrochemical oxidation efficiency and low energy consumption.

Moreover, the filter type electrochemical reactor of the present invention is convenient to operate, green and safe, and can realize continuous dynamic treatment of sewage without aeration and addition of chemical reagents.

Description of drawings

FIG. 1 is a schematic cross-sectional view of the filtering electrochemical reactor of Example 1.

2 is a schematic diagram of the electrochemical water treatment device of Example 2.

Figure 3 is a comparison of the effects of Example 3 and Comparative Example 1 in treating printing and dyeing wastewater containing rhodamine B.

The schematic diagram of common plate type, non-filter type electrochemical device used in Fig. 4 comparative example.

Detailed ways

The present invention will be further described below in combination with specific embodiments.

In an embodiment, the calculation formula of energy consumption is:

U is the average voltage (V) when degrading organic pollutants; I is the applied current (A) for degrading organic pollutants; t _99.9% is the time (min) for the degradation rate of organic pollutants to reach 99.9%, and V is the volume of the reaction solution (L). In an embodiment, organic pollutants include rhodamine B, phenol, and dimethoate pesticide wastewater.

In the embodiments, "power consumption" refers to consumed electric energy, that is, energy consumption.

Example 1

A filter type electrochemical reactor, as shown in Figure 1, comprises a tubular reactor wall 1, a three-layer tubular porous electrode 2 that is sleeved on the tubular reactor wall 1, and a water distribution pipe 3 that is sleeved on the tubular porous electrode 2, The three-layer tubular porous electrode 2 forms a casing structure, which is the first tubular porous electrode 2, the second tubular porous electrode 2, and the third tubular porous electrode 2 from the inside to the outside, and the water distribution pipe 3 is sleeved inside the first tubular porous electrode 2. The openings at both ends of the tubular reactor wall 1 and the tubular porous electrode 2 are encapsulated by a plexiglass flange 4 through bolts; the filtering electrochemical reactor of the present embodiment is provided with a water outlet 5, the third tubular porous electrode 2, the tubular reaction The cavity formed by the device wall 1 and the plexiglass flange 4 communicates with the water outlet 5;

The tubular reactor wall 1 is made of stainless steel;

A part of the water distribution pipe 3 protrudes out of the filter type electrochemical reactor, and this part is provided with a water inlet. The part of the filter type electrochemical reactor of the water distribution pipe 3 is provided with a through hole with an aperture of 1 mm. The water distribution pipe 3 is made of stainless steel. to make;

The first tubular porous electrode 2 adopts a porous titanium-based tin-antimony electrode, the porous titanium-based tin-antimony electrode is Ti/Sn-SbO ₂ , the porosity of the first tubular porous electrode 2 is 50%, and the filtration accuracy of the first tubular porous electrode 2 is The second tubular porous electrode 2 is made of porous titanium tube, the porosity of the second tubular porous electrode 2 is 50%, and the filtration accuracy of the second tubular porous electrode 2 is 10 μm; the third tubular porous electrode 2 is made of porous titanium A tin-antimony-based electrode, the porosity of the third tubular porous electrode 2 is 50%, and the filtration accuracy of the third tubular porous electrode 2 is 0.2 μm;

The distance between the water distribution pipe 3, the first tubular porous electrode 2, the second tubular porous electrode 2, the third tubular porous electrode 2 and the tubular reactor wall 1 is 1 cm; the diameter of the water distribution pipe is 2 cm, and all the tubular porous electrodes The height is 20 cm.

The water distribution pipe 3, the second tubular porous electrode 2 and the tubular reactor wall 1 are set as cathodes, the first tubular porous electrode 2 and the third tubular porous electrode 2 are set as anodes, and the filter type electrochemical reactor of the present embodiment is also provided with The terminal is connected to the cathode as the cathode terminal, and the one connected to the anode is the anode terminal.

Example 2

A kind of electrochemical water treatment device, as shown in Figure 2, comprises filter type electrochemical reactor 7 and DC power supply 8 of embodiment 1, also comprises water inlet tank 12, booster pump 11, flow meter 10, water inlet pressure gauge 9 and the water outlet pressure gauge 13, the water inlet of the water inlet tank 12, the booster pump 11, the flowmeter 10, the water inlet pressure gauge 9, and the filter electrochemical reactor 7 are connected by pipelines successively, and the outlet of the filter electrochemical reactor 7 The water outlet 5, the water outlet pressure gauge 13, and the water inlet tank 12 are connected through pipelines in sequence.

Example 3

An electrochemical water treatment method, using the electrochemical water treatment device of embodiment 2 to treat printing and dyeing wastewater containing rhodamine B.

S1. Connect the negative pole of the DC power supply 8 to the cathode terminal, and the positive pole of the DC power supply 8 to the anode terminal;

S2. Put 2 L of printing and dyeing wastewater containing Rhodamine B at an initial concentration of 200 mg/L in the water inlet tank ₁₂ , add Na in the water inlet tank ₁₂ SO supporting electrolyte, make its concentration 50 mM, turn on the power, Using constant current mode, adjust the current density to 20 mA/cm ² ;

S3. Turn on the booster pump 11, adjust the pressure difference between the inlet water and the outlet water of the filter electrochemical reactor 7 to be 1.0 MPa, and the printing and dyeing wastewater enters the filter electrochemical reactor 7 through the pipeline and the water distribution pipe 3, and then flows through the filter electrochemical reactor 7 in sequence. A tubular porous electrode 2 and a second tubular porous electrode 2; after the printing and dyeing wastewater flows through the tubular porous electrodes 2 with different filtration precisions in sequence, the organic pollutants in the printing and dyeing wastewater are filtered and oxidized step by step.

S3. After one treatment, the printing and dyeing wastewater flows back to the water inlet tank 12 from the water outlet 5 through the pipeline, and its chroma is obviously reduced.

Example 4

In this example, an electrochemical water treatment device was used to treat organic wastewater containing phenol; the organic wastewater had an initial concentration of 200 mg/L, an initial pH of 8.4, and a volume of 2 L.

The difference between the electrochemical water treatment device used in this example and the electrochemical water treatment device used in Example 3 is that the first tubular porous electrode 2 is made of porous titanium dioxide with a porosity of 70% and a filtration accuracy of 20 μm. Lead electrode, the second tubular porous electrode 2 adopts a stainless steel tube with a porosity of 70% and a filtration precision of 1 μm, and the third tubular porous electrode 2 adopts a porous titanium-based lead dioxide with a porosity of 70% and a filtration precision of 0.05 μm The electrodes and the water distribution pipe 3 are made of copper; others are the same as the electrochemical water treatment device adopted in embodiment 3;

The difference between the conditions for treating wastewater in this embodiment and that of Embodiment 3 is that the pressure difference between the inlet and outlet water is 3.5 MPa, and the others are the same as in Embodiment 3.

Example 5

The difference between this embodiment and Example 3 is that the organic waste water treated is the high-concentration dimethoate pesticide waste water of a certain chemical plant in Jiangsu, and others are the same as in Example 3; the initial COD of this waste water is 12418 mg/L, and the initial pH value is 3.2, with a volume of 1 L.

Comparative example 1

The difference from Example 3 is that the filter electrochemical reactor is replaced with a common plate type, non-filter electrochemical device, and other experimental conditions are the same;

The common plate-type, non-filter-type electrochemical device in this comparative example, structure as shown in Figure 4, comprises 5 parallel plate electrodes placed in parallel, alternately arranged as anode and cathode successively, the surface area of the parallel plate electrodes is the same as that of the second tubular porous The outer areas of the electrodes are equal (about 20×0.25 cm ² ), and the distance between the electrodes is 1 cm; the electrode materials are the same as in Example 3.

Comparative example 2

The difference from Example 4 is that the filtered electrochemical reactor is replaced with a common plate type, non-filtered electrochemical device, and other experimental conditions are the same;

The structure of the ordinary plate-type, non-filtering electrochemical device in this comparative example is the same as that of the common plate-type, non-filtering electrochemical device in Comparative Example 1; the electrode materials are the same as in Example 4.

The results of embodiment 3 and comparative example 1 are as shown in Figure 3, in embodiment 3, after crossing 10 min minute, the analysis result of ultraviolet-visible spectrophotometer shows, the removal rate of Rhodamine B has reached more than 99.9%, calculate The power consumption was only 1.81 WhL ^-1 ; the treatment effect of Example 3 was significantly better than that of Comparative Example 1; the rate constant and power consumption of Example 3 were 11.7 times and 1/13.1 of those of Comparative Example 1, respectively.

The results of Example 4 and Comparative Example 2 are shown in Table 1. The degradation effect of Example 4 is significantly higher than that of Comparative Example 2. The time required for Example 4 and Comparative Example 2 to reach a removal rate of 99.9% is 8 min respectively. and 90 min, the filter type electrochemical reactor and electrochemical water treatment device of the present invention obviously have higher electrochemical oxidation efficiency and lower energy consumption.

The result of table 1 embodiment 4 and comparative example 2

t _99.9% (min) Rate constant K (min ^-1 ) Power consumption W (WhL ^-1 ) Example 4 8 0.145 1.12 Comparative example 2 90 0.029 7.34

In Example 5, after 10 minutes of reaction, the COD of the wastewater was reduced to 1107 mg/L, and the COD removal rate was as high as 91.1%; after 18 minutes, the COD of the wastewater was completely removed.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (7)

1. a kind of filter type electric chemical reactor, which is characterized in that including nested water distributor successively from inside to outside（3）, multilayer Tubular porous electrode（2）, tubular reactor wall（1）, the tubular porous electrode（2）With tubular reactor wall（1）Both ends open Mouth uses sealing structure（4）Encapsulation, the water distributor（3）Across the sealing structure（4）, the water distributor（3）Equipped with water inlet Mouthful, the outermost tubular porous electrode（2）With tubular reactor wall（1）The cavity of composition is equipped with water outlet（5）；

The water distributor（3）With tubular reactor wall（1）It is made of conductive material, the water distributor（3）And tubular reactor Wall（1）It is set as cathode；Tubular porous electrode described in multilayer（2）It is alternatively set as anode and cathode from inside to outside；The tubulose Porous electrode（2）Porosity be more than or equal to 45%.

2. filter type electric chemical reactor according to claim 1, which is characterized in that the tubular porous electrode（2）'s Porosity is 45% ~ 80%.

3. filter type electric chemical reactor according to claim 2, which is characterized in that the tubular porous electrode（2）'s Porosity is 45% ~ 60%.

4. filter type electric chemical reactor according to claim 1, which is characterized in that the tubular porous electrode（2）'s Filtering accuracy improves successively from inside to outside.

5. filter type electric chemical reactor according to claim 1 or 4, which is characterized in that the tubular porous electrode（2） Filtering accuracy be 0.02 ~ 100 μm.

6. a kind of device for electrochemical water preparation, which is characterized in that including claim 1 ~ 5 any one of them filter type electric chemistry Reactor（7）, DC power supply（8）, booster pump（11）.

7. a kind of electrochemical water treating method, which is characterized in that include the following steps：

S1. supporting electrolyte is added in organic wastewater；

S2. by claim 1 ~ 5 any one of them filter type electric chemical reactor（7）DC power supply is connected, by having for S1. Machine waste water is passed through the water distributor（3）, organic wastewater is after processing from the water outlet（5）Outflow.