An electrodialysis-three-dimensional electrode reaction method for simultaneous desalination and pollution reduction of high-salinity landfill leachate

Abstract

The application discloses a kind of electrodialysis-three-dimensional electrode reaction methods for high salt garbage leachate synchronous desalination and pollution reduction.The application will use tea dregs as raw material to prepare a kind of magnetic nitrogen-doped biochar particle electrode material, placed in the concentration chamber of electrodialysis reaction tank to construct three-dimensional electrode reaction system, through the way of aeration, make the particle electrode suspended, in the process of reactor electrification, utilize the electrochemical performance of particle electrode and the condition of high salt in concentration chamber, degrade organic pollutants in concentration chamber.The electrodialysis-three-dimensional electrode reaction system constructed by the application can separate salt while degrading organic pollutants efficiently by using the salt separated in concentration chamber, and further guarantee the resource utilization efficiency of high salt organic wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to a water body synchronous desalination and pollution reduction method, and particularly relates to an electrodialysis-three-dimensional electrode reaction system for synchronous desalination and pollution reduction of high-salt landfill leachate. BACKGROUND

[0002] Landfill leachate has certain difficulties in treatment due to high salt and serious organic pollution. How to desalinate landfill leachate and treat organic pollution in a high-salt environment is worth paying attention to. Electrodialysis is a common desalination technology, which has the advantage of operating at normal temperature and pressure, avoiding energy consumption caused by changing temperature and pressure, and having low dependence on environmental temperature and moderate dependence. It is an environmentally friendly and efficient desalination technology. In the electrodialysis reaction tank, anions and cations are arranged alternately to form several separated reaction tanks. After a certain period of time, the reaction tank will alternately form a concentrated chamber containing anions and cations, and a dilute chamber with low ion concentration. Because the concentrated chamber has high salt content, the treatment of organic pollutants in the subsequent concentrated chamber is extremely difficult. How to use the electrical energy and salt in the electrodialysis reaction process to construct an electrochemical synchronous degradation system to reduce organic pollutants in the concentrated chamber has practical value for pollution treatment of high-salt wastewater.

[0003] Three-dimensional electrode technology is a very potential electrochemical oxidation technology, which refers to selecting a granular electrode to be filled between the cathode and the anode of the traditional two-dimensional electrode. The filled granular electrode has the characteristics of anode and cathode and forms an independent electrode unit under the action of the current of the electric field during the operation of the reactor. The reaction area of the traditional two-dimensional electrode is mainly on the surface of the two electrodes, but the three-dimensional electrode technology can expand the reaction area to the entire reactor, increase the utilization rate of the reactor space without increasing the volume of the reactor, and improve the reaction efficiency of the entire reactor. Three-dimensional electrode has become a high-efficiency organic pollution remediation technology, and the water treatment effect is better than that of two-dimensional electrode. The salt ions in high-salt wastewater can be used as electrolytes to improve the degradation effect of organic pollutants. Therefore, adding granular electrodes in the concentrated chamber to construct an electrodialysis-three-dimensional electrode electrochemical system is beneficial to the degradation of organic pollutants in the concentrated chamber, and can meet the demand of resource utilization of high-salt aquaculture wastewater.

[0004] Biomass charcoal is widely used in the field of granular electrode, which has the advantages of low price, wide source and avoiding resource waste. However, the poor treatment effect limits the application of biomass charcoal in three-dimensional electrode system. Doping nitrogen element can make the carbon framework form asymmetric electronic defect sites. The electronegativity of nitrogen atom is greater than that of carbon atom, and the electron is transferred from carbon atom to nitrogen atom, which improves the conductivity and catalytic performance of the granular electrode. At present, the doping method of external nitrogen source is not only complex in operation, but also easy to cause environmental pollution. China is the largest tea producing country in the world, with annual tea output of 2.1 million tons, accounting for 44.7% of the world's share, of which more than 90% of the tea will be discarded after drinking. Tea residue has high carbon content and contains rich cellulose, hemicellulose, lignin and other substances, which can be used as biomass charcoal raw material. In addition, tea residue has high nitrogen content, and nitrogen-doped biomass charcoal can be prepared without external nitrogen source. At present, ferromagnetic modification is an effective way to give biomass charcoal recovery performance, and the use of ferromagnetic modification method to prepare magnetic nitrogen-doped tea residue biomass charcoal granular electrode not only facilitates the recovery and reuse of the granular electrode, but also can further improve the treatment effect of the reaction system. The tea residue biomass charcoal is prepared into magnetic nitrogen-doped granular electrode and placed in the electrodialysis concentration chamber to construct a three-dimensional electrode reaction system, which is an effective method for simultaneously reducing the salt content and organic pollutants of high-salinity landfill leachate. SUMMARY

[0005] In order to solve the problem of difficult removal of organic pollutants in the concentration chamber during the treatment of high-salinity wastewater by electrodialysis, the present application provides an electrodialysis-three-dimensional electrode reaction method for simultaneous desalination and pollution reduction of high-salinity organic wastewater.

[0006] The technical scheme adopted by the present application is as follows.

[0007] The present application provides an electrodialysis-three-dimensional electrode reaction method for simultaneous desalination and pollution reduction of high-salinity landfill leachate, and the specific steps are as follows:

[0008] (1) Put the tea residue in a tube furnace and heat it in a nitrogen environment at 400-600°C for 1 h to obtain biomass charcoal.

[0009] (2) Mix the tea residue biomass charcoal in step (1) with KOH at a ratio of 1:1, heat it in a nitrogen environment for 1 h, and set the temperature at 300-600°C. Wash it with ultrapure water for 3 times to obtain nitrogen-doped tea residue biomass charcoal.

[0010] (3) Put 1 g of tea residue biomass charcoal in step (2) and 2 g of ferric chloride and 0.5 g of ferroferric oxide in a 500 mL conical flask, add 60 mL of deionized water, and use 1 mol L -1The pH was adjusted to 10 with NaOH to precipitate iron oxides, and the mixture was stirred in an 80℃ water bath for 1 h. After standing and cooling to room temperature, the mixture was washed three times with ethanol and three times with deionized water to remove unprecipitated iron oxides. The precipitated iron oxides were then dried at 80℃ for 24 h to obtain magnetic tea residue biochar.

[0011] (4) Place 1–10 g of the magnetic biochar prepared in step (3) into the concentration chamber of the electrodialysis-three-dimensional electrode reactor. The electrodialysis-three-dimensional electrode reactor uses a membrane stack of 10–20 pairs of membranes. The electrodialysis membrane material is a polystyrene heterogeneous ion exchange membrane with an effective area of ​​200–400 cm². 2 The electrodes at both ends are made of ruthenium-iridium titanium-plated plates, and the flow rate of landfill leachate into the water is adjusted to 1–10 L / h. -1 The reaction voltage is 5–20 V, and the NaCl concentration is 10–30 g / L. -1 .

[0012] (5) Aerate the concentration chamber to suspend the particulate electrode and prevent it from settling to the bottom. The aeration rate is 10–20 L / min. -1 Aeration can also increase the oxygen content in the solution and improve the treatment effect.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The electrodialysis-three-dimensional electrode reaction method constructed by the present invention adds a particulate electrode to the electrodialysis concentrate chamber, which can simultaneously reduce organic pollutants by utilizing the salt in the concentrate chamber and the electrical energy of the electrodialysis desalination process. This not only saves electrical energy, but also facilitates the resource utilization of the concentrate chamber water. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the electrodialysis-three-dimensional electrode reaction system.

[0015] Figure 2 It refers to the chloride ion removal rate in the dilute chamber during the treatment of high-salt landfill leachate using the electrodialysis-three-dimensional electrode reactor in Example 1.

[0016] Figure 3 This refers to the change in chemical oxygen demand in the concentration chamber of the electrodialysis-three-dimensional electrode reactor used in Example 2 for treating high-salt landfill leachate. Implementation

[0017] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] like Figure 1 As shown, Figure 1is a schematic diagram of the reaction system, landfill leachate enters the electrodialysis- three dimensional electrode reactor through the peristaltic pump; the concentrated chamber in the reactor refers to the reaction area in which anions and cations continuously enter and the concentration continuously increases during the reaction; the dilute chamber in the reactor refers to the reaction area in which anions and cations continuously flow out and the concentration continuously decreases during the reaction; the organic pollutants in the concentrated chamber are difficult to treat, so the granular electrode is added in the concentrated chamber; during the reaction, the granular electrode is suspended by aeration, which can also improve the treatment effect. Example 1

[0019] (1) Put the tea dregs into a tube furnace and heat in a nitrogen environment at 500°C for 1 h to obtain biochar.

[0020] (2) Mix the tea dregs biochar in step (1) with KOH at a ratio of 1:1, heat in a nitrogen environment for 1 h, and set the temperature at 500°C. Wash with ultrapure water for 3 times to obtain nitrogen-doped tea dregs biochar.

[0021] (3) Put 1 g of tea dregs biochar in step (2) and 2 g of ferric chloride and 0.5 g of ferroferric oxide into a 500 mL conical flask, add 60 mL of deionized water, and use 1 mol L -1 of NaOH to adjust the pH to 10 to precipitate iron oxide, and stir in a 80°C water bath for 1 h. After standing and cooling to room temperature, wash with ethanol and deionized water for 3 times respectively to wash away the unprecipitated iron oxide, and dry at 80°C for 24 h to obtain magnetic tea dregs biochar.

[0022] (4) Put 4 g of the magnetic biochar prepared in step (3) into the concentrated chamber of the electrodialysis- three dimensional electrode reactor, the electrodialysis- three dimensional electrode reactor uses a membrane stack of 20 pairs of membranes, the electrodialysis membrane material is polystyrene-based heterogeneous ion exchange membrane, the effective area is 400 cm 2 , the electrode material at both ends is ruthenium-iridium titanium plate electrode, the flow rate of landfill leachate is adjusted to 1 L h -1 , the reaction voltage is 5 V, and the NaCl concentration is 10 g L -1 .

[0023] (5) Aerate the concentrated chamber to suspend the granular electrode and prevent the granular electrode from sinking to the bottom, the aeration amount is 10 Lmin -1 , and aeration can also increase the oxygen content in the solution to improve the treatment effect.

[0024] In Example 1, the number of membrane stacks is increased, which can increase the desalination rate during the reaction, and is suitable for reaction systems with high salt content and low organic pollution degree. Example 2

[0025] (1) Tea residues were placed in a tube furnace and heated in a nitrogen environment at 500°C for 1 h to obtain biochar.

[0026] (2) The tea residue biochar in step (1) was mixed with KOH at a ratio of 1:1, heated in a nitrogen environment for 1 h, and the temperature was set at 500°C. Washed with ultrapure water 3 times to obtain nitrogen-doped tea residue biochar.

[0027] (3) 1 g of tea residue biochar in step (2) was placed in a 500 mL conical flask with 2 g of ferric chloride and 0.5 g of ferroferric oxide, 60 mL of deionized water was added, and 1 mol L -1 of NaOH was used to adjust the pH to 10 to precipitate iron oxide, and stirred in a water bath at 80°C for 1 h. After standing and cooling to room temperature, washed with ethanol and deionized water for 3 times respectively to wash away the unprecipitated iron oxide, and dried at 80°C for 24 h to obtain magnetic tea residue biochar.

[0028] (4) 10 g of the magnetic biochar prepared in step (3) was placed in each of the concentration chambers of the electrodialysis-three-dimensional electrode reactor, the electrodialysis-three-dimensional electrode reactor used a membrane stack of 10 pairs of membranes, the electrodialysis membrane material was a polystyrene-based heterogeneous ion exchange membrane, the effective area was 300 cm 2 , the electrode materials at both ends were ruthenium-iridium titanium plate electrodes, the water flow rate was adjusted to 3 L h -1 , the reaction voltage was 10 V, and the NaCl concentration was 20 g L -1 .

[0029] (5) The concentration chamber was aerated to suspend the granular electrode to prevent the granular electrode from sinking to the bottom, and the aeration amount was 20 Lmin -1 , and the aeration also increased the oxygen content in the solution to improve the treatment effect.

[0030] As shown in Figure 2 , the rice hull control group is the treatment effect of replacing the magnetic nitrogen-doped tea residue biochar in the concentration chamber with rice hull biochar; wherein the preparation conditions of the rice hull are: heating in a nitrogen environment, heating temperature is 500°C, and heating time is 2 h. The increase of the dosage of the granular electrode in the concentration chamber and the aeration amount in Example 2 is beneficial to the removal of organic pollutants during the reaction process, and is suitable for high-salinity wastewater with serious organic pollution.

[0031] The above only describes the preferred embodiments of the present application and does not limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An electrodialysis-three-dimensional electrode reaction method for simultaneous desalination and pollution reduction of high-salinity landfill leachate, characterized by, The specific steps are as follows: The tea residue was placed in a tube furnace and heated in a nitrogen environment at 400-600°C for 1 h to obtain biochar; the prepared tea residue biochar was mixed with KOH at a ratio of 1:1, heated in a nitrogen environment for 1 h, with a temperature setting of 300-600°C, washed with ultrapure water 3 times to obtain nitrogen-doped tea residue biochar; 1 g of tea residue biochar was placed in a 500 mL conical flask with 2 g of ferric chloride and 0.5 g of ferroferric oxide, 60 mL of deionized water was added, and 1 mol L -1 of NaOH was used to adjust the pH to 10 to precipitate iron oxide, and stirred in an 80°C water bath for 1 h; after standing and cooling to room temperature, the unprecipitated iron oxide was washed away by suction filtration with ethanol and deionized water for 3 times, and dried at 80°C for 24 h to obtain magnetic tea residue biochar; 1-10 g of the prepared magnetic biochar was evenly placed in each concentration chamber of the electrodialysis-three-dimensional electrode reactor, the electrodialysis-three-dimensional electrode reactor used a membrane stack of 10-20 pairs of membranes, the electrodialysis membrane material was a polystyrene-based heterogeneous ion exchange membrane, the effective area was 200-400 cm 2 , the electrode material at both ends was a ruthenium-iridium titanium-plated plate electrode, the waste leachate inflow rate was adjusted to 1-10 Lh -1 , the reaction voltage was 5-20 V, and the NaCl concentration was 10-30 g L -1 ; the concentration chamber was aerated to suspend the granular electrode to prevent the granular electrode from sinking to the bottom, the aeration amount was 10-20 Lmin -1 , and aeration could also increase the oxygen content in the solution to improve the treatment effect.

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