A process, apparatus, catalyst and method of preparation for removing meta-toluidine and indole from coking nanofiltration concentrated water

Abstract

The application provides a process and equipment for removing m-methylaniline and indole in coking nanofiltration concentrated water, a catalyst and a preparation method thereof, and the water quality of the coking nanofiltration concentrated water is as follows: conductivity 21300-34560 muS / cm, sulfate ion 567-1340 mg / L, m-methylaniline 45-78 mu g / L, and indole 23-39 mu g / L; the process comprises the following treatment steps: the coking nanofiltration concentrated water enters the ozone catalytic tower from the bottom of the tower and flows out from bottom to top, and the ozone catalytic tower is internally provided with a modified peanut shell biochar catalyst; after the ozone catalytic reaction, the water quality of the coking nanofiltration concentrated water is as follows: conductivity 21300-34560 muS / cm, sulfate ion 567-1340 mg / L, m-methylaniline 3-7 mu g / L, and indole 1-6 mu g / L.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and relates to a technology and method for deep treatment of coking nanofiltration concentrate. Specifically, it relates to a process, equipment, catalyst, and preparation method for removing m-methylaniline and indole from coking nanofiltration concentrate. Background Technology

[0002] Coking wastewater is wastewater formed during the high-temperature dry distillation of coal, as well as the purification of coal gas and the refining of chemical products. It contains dozens of pollutants such as phenols, ammonia nitrogen, cyanide, m-methylaniline and indole. It has a complex composition, high concentration of organic pollutants, high color and toxicity, and is very stable. It is a typical type of recalcitrant organic wastewater.

[0003] Wastewater reuse is the ultimate goal of wastewater treatment and a means for enterprises to implement energy conservation and emission reduction. Currently, simple coking wastewater reuse technologies can no longer meet the requirements of enterprises; therefore, deep treatment of biochemically treated coking wastewater before reuse is an inevitable trend.

[0004] In China, advanced treatment technologies for coking wastewater employ nanofiltration and reverse osmosis to treat the wastewater and reuse it as circulating cooling water for steel enterprises. However, a major problem lies in the treatment of the concentrated wastewater generated by reverse osmosis. Nanofiltration concentrate from coking plants contains large amounts of m-methylaniline and indole.

[0005] m-Toluidine, also known as 3-toluidine, is an organic compound with the chemical formula C7H9N. It is a colorless, oily liquid, primarily used as an intermediate in the manufacture of vat dyes. Routes of entry for m-toluidine include inhalation, ingestion, and dermal absorption. m-Toluidine is a potent methemoglobin-forming agent and can irritate the bladder and urethra, causing hematuria. Acute poisoning often occurs through skin contamination and absorption, causing symptoms such as facial burning, severe headache, dizziness, difficulty breathing, and cyanosis. Later, hematuria, urinary retention, mental disorders, and muscle convulsions may develop.

[0006] Indole is a compound formed by the symmetric combination of pyrrole and benzene, also known as benzopyrrole, with the chemical formula C8H7N. Indole has a strong, fecal odor and exhibits strong and persistent diffusion. The acute toxicity median lethal dose (LD50) of indole is: oral (rat) 1000 mg / kg; dermal (rabbit) 790 mg / kg.

[0007] Therefore, if pollutants such as m-methylaniline and indole generated in nanofiltration processes are discharged directly without treatment, they will inevitably cause great harm to the aquatic environment.

[0008] To date, there are no low-cost processes or methods for intermediate methylaniline and indole in coking nanofiltration concentrate. Summary of the Invention

[0009] The technical problem to be solved by this invention is to provide an economical and efficient process for removing m-methylaniline and indole from coking nanofiltration concentrate, based on the water quality and quantity conditions of the concentrate.

[0010] The technical problem it aims to solve can be addressed through the following technical solutions.

[0011] A process for removing intermediate-methylaniline and indole from coking nanofiltration concentrate, wherein the concentrate has the following characteristics: conductivity 21300–34560 μS / cm, sulfate ion concentration 567–1340 mg / L, m-methylaniline 45–78 μg / L, and indole 23–39 μg / L; characterized by the following treatment steps:

[0012] The concentrated water from coking nanofiltration enters the ozone catalytic tower from the bottom and flows out from bottom to top. The ozone catalytic tower is filled with modified peanut shell biochar catalyst.

[0013] After ozone catalysis, the conductivity of the coking nanofiltration concentrate is 21300–34560 μS / cm, the sulfate ion concentration is 567–1340 mg / L, the m-methylaniline concentration is 3–7 μg / L, and the indole concentration is 1–6 μg / L.

[0014] As a further improvement to this technical solution, the ozone generator in the ozone catalytic tower is an oxygen source generator. The generated ozone enters the ozone catalytic tower from the bottom and then fills the entire catalytic tower, with an ozone concentration of 90–105 g / m³. 3 .

[0015] As a further improvement to this technical solution, the modified peanut shell biochar catalyst accounts for 75-85% of the total volume of the ozone catalytic tower, and the residence time of the nanofiltration concentrate in the ozone catalytic tower is 27-46 min.

[0016] As a further improvement to this technical solution, the modified peanut shell biochar catalyst is prepared using the following method:

[0017] 1) Raw material selection:

[0018] Prepare a 0.4–1.2 mol / L sodium hydroxide solution. Using peanut shells as biochar raw material, soak the rinsed peanut shells in the sodium hydroxide solution for 125–150 minutes. After removing them, air dry them and perform the first baking, followed by natural cooling.

[0019] 2), carbonization:

[0020] The peanut shells processed in step 1) are placed in a muffle furnace and heated to 620-695℃ at a rate of 6-9℃ / min. The mixture is then pyrolyzed for 90-105 min and allowed to cool naturally to form peanut shell biochar.

[0021] The obtained peanut shell biochar was ground into fine powder and screened into 100-300 mesh peanut shell biochar fine powder;

[0022] 3) Biochar modification:

[0023] Based on the metal element, prepare a manganese nitrate solution with a concentration of 8-11% and a ferric nitrate solution with a concentration of 4-7%, and then mix these two solutions in a volume ratio of (2-4):1 to form a mixed solution and put it into the reaction vessel;

[0024] In the reactor, the mixture is heated to 78–83°C under nitrogen protection and aged at a constant temperature for 7–9 hours. After cooling, it is filtered, the peanut shell biochar is washed with water, and then baked a second time. After cooling, it forms a modified peanut shell biochar catalyst.

[0025] Preferably, the first baking is carried out in an oven at 105°C for 2-4 hours; the second baking is carried out in an oven at 105°C for 2-4 hours.

[0026] Another technical problem to be solved by the present invention is to provide an apparatus for implementing the aforementioned process. The apparatus includes an ozone generating tower, the bottom of which is connected to an inlet pipe for nanofiltration concentrate to be treated, the top or upper part of which is connected to an outlet pipe, and the bottom of which is also connected to an ozone inlet pipe for introducing ozone, the ozone inlet pipe being connected to an external ozone generator; a modified peanut shell biochar catalyst is disposed inside the ozone generating tower.

[0027] Furthermore, the ozone concentration inside the ozone catalytic tower is 90–105 g / m³. 3 The modified peanut shell biochar catalyst accounts for 75-85% of the total volume of the ozone catalytic tower.

[0028] Another technical problem to be solved by the present invention is to provide a method for preparing the aforementioned modified peanut shell biochar catalyst, comprising the following steps:

[0029] 1) Raw material selection:

[0030] Prepare a 0.4–1.2 mol / L sodium hydroxide solution. Using peanut shells as biochar raw material, soak the rinsed peanut shells in the sodium hydroxide solution for 125–150 minutes. After removing them, air dry them and perform the first baking, followed by natural cooling.

[0031] 2), carbonization:

[0032] The peanut shells processed in step 1) are placed in a muffle furnace and heated to 620-695℃ at a rate of 6-9℃ / min. The mixture is then pyrolyzed for 90-105 min and allowed to cool naturally to form peanut shell biochar.

[0033] The obtained peanut shell biochar was ground into fine powder and screened into 100-300 mesh peanut shell biochar fine powder;

[0034] 3) Biochar modification:

[0035] Based on the metal element, prepare a manganese nitrate solution with a concentration of 8-11% and a ferric nitrate solution with a concentration of 4-7%, and then mix these two solutions in a volume ratio of (2-4):1 to form a mixed solution and put it into the reaction vessel;

[0036] In the reactor, the mixture is heated to 78–83°C under nitrogen protection and aged at a constant temperature for 7–9 hours. After cooling, it is filtered, the peanut shell biochar is washed with water, and then baked a second time. After cooling, it forms a modified peanut shell biochar catalyst.

[0037] Furthermore, the first baking is carried out in an oven at 105°C for 2 to 4 hours; the second baking is carried out in an oven at 105°C for 2 to 4 hours.

[0038] The present invention also provides a catalyst obtained by the above preparation method.

[0039] The advanced treatment system and process for coking nanofiltration concentrate provided by this invention aims to solve the environmental pollution problem caused by the emission of intermediate methylaniline and indole from coking nanofiltration concentrate. The advanced treatment system and process of this invention have low initial investment, simple operation, and low production costs, making it an environmentally friendly green treatment process for steel wastewater. The corresponding advanced treatment process and equipment for coking nanofiltration concentrate prioritize green technology and energy conservation and emission reduction, thereby reducing environmental pollution and actively responding to increasingly stringent environmental protection regulations. Attached Figure Description

[0040] Figure 1 This is a simplified diagram of the equipment used in the system for removing intermediate methylaniline and indole from coking nanofiltration concentrate according to the present invention.

[0041] In the diagram: 1—Inlet pump, 2—Ozone catalytic reaction tower, 3—Ozone generator, 4—Modified peanut shell biochar catalyst, 5—Outlet pump. Detailed Implementation

[0042] The system equipment for removing intermediate methylaniline and indole from coking nanofiltration concentrate provided by the present invention mainly includes an inlet pump 1, an ozone catalytic reaction tower 2, an ozone generator 3, a modified peanut shell biochar catalyst 4, and an outlet pump 5.

[0043] The target coking nanofiltration concentrate has a conductivity of 21300–34560 μS / cm, a sulfate ion concentration of 567–1340 mg / L, a m-methylaniline concentration of 45–78 μg / L, and an indole concentration of 23–39 μg / L.

[0044] The concentrated coking nanofiltration water enters the ozone catalytic reaction tower 2 via inlet pump 1. The ozone catalytic tower 2 is equipped with a modified peanut shell biochar catalyst 4. The nanofiltration concentrated water enters the ozone catalytic tower 2 from the bottom and flows out from bottom to top. Ozone generator 3 is an oxygen source generator; the ozone it produces enters the catalytic tower from the bottom of the ozone catalytic reaction tower 2 and then fills the entire tower, with an ozone concentration of 90–105 g / m³. 3 The modified peanut shell biochar catalyst accounts for 75-85% of the total volume of the ozone catalytic tower, and the residence time of the nanofiltration concentrate in the tower is 27-46 minutes.

[0045] To address the high conductivity of nanofiltration concentrate from coking plants, this invention specifically develops and prepares a modified peanut shell biochar catalyst. This catalyst simultaneously removes intermediate methylaniline and indole from the nanofiltration concentrate. The preparation method of the modified peanut shell biochar catalyst of this invention is as follows:

[0046] 1) Raw material selection:

[0047] Peanut shells are used as biochar raw material. First, rinse them with tap water 2 to 3 times, prepare a 0.4 to 1.2 mol / L sodium hydroxide solution, soak the peanut shells in the sodium hydroxide solution for 125 to 150 minutes, take them out and dry them, place them in a 105℃ oven for 2 to 4 hours, and let them cool naturally.

[0048] 2), carbonization:

[0049] Peanut shells are placed in a muffle furnace and heated to 620-695℃ at a rate of 6-9℃ / min. The mixture is then pyrolyzed for 90-105 minutes and allowed to cool naturally to form peanut shell biochar. The peanut shell biochar is then ground into fine powder using a grinder and screened to a mesh size of 100-300.

[0050] 3) Biochar modification:

[0051] Prepare a manganese nitrate solution with a concentration of 8-11% (calculated by metal element) and a ferric nitrate solution with a concentration of 4-7%. Then, mix these two solutions at a volume ratio of (2-4):1 and place them into a reaction vessel. In the reaction vessel, heat to 78-83℃ under nitrogen protection and age at a constant temperature for 7-9 hours. After cooling, filter, wash the peanut shell biochar with water 3-5 times, dry it in an oven at 105℃ for 2-4 hours, and then cool to form a modified peanut shell biochar catalyst.

[0052] The modified peanut shell biochar catalyst has a rough and porous surface, exhibiting good water absorption and ion exchange capabilities. Manganese and iron metals can be effectively supported on the surface of the peanut shell biochar. The specific surface area of ​​the prepared modified peanut shell biochar catalyst is 123.1–145.6 m². 2 / g, with a metal loading rate of 4–7% (measured by gravimetric method). The prepared modified peanut shell biochar catalyst exhibits good physical properties and can effectively convert ozone into hydroxyl radicals, degrade, and adsorb ozone in ozone catalytic oxidation reactions.

[0053] After ozone catalysis, the conductivity of the coking nanofiltration concentrate is 21300–34560 μS / cm, the sulfate ion concentration is 567–1340 mg / L, the m-methylaniline concentration is 3–7 μg / L, and the indole concentration is 1–6 μg / L.

[0054] Subsequently, the drainage pump discharges the coking nanofiltration concentrate.

[0055] To better understand this invention patent, the following embodiments further illustrate the content of this invention patent, but the content of this invention patent is not limited to the following embodiments.

[0056] Example 1:

[0057] In this embodiment, the electrical conductivity of the coking nanofiltration concentrate is 34560 μS / cm, the sulfate ion concentration is 1340 mg / L, the m-methylaniline concentration is 78 μg / L, and the indole concentration is 32 μg / L.

[0058] The concentrated coking nanofiltration water enters the ozone catalytic reaction tower via an inlet pump. The ozone catalytic tower is equipped with a modified peanut shell biochar catalyst. The nanofiltration water enters the tower from the bottom and flows out from the top. The ozone generator is an oxygen source generator; the generated ozone enters the catalytic tower from the bottom and then fills the entire tower, achieving an ozone concentration of 105 g / m³. 3 The modified peanut shell biochar catalyst accounts for 85% of the total volume of the ozone catalytic tower, and the residence time of the nanofiltration concentrate in the tower is 46 minutes.

[0059] To address the high conductivity of nanofiltration concentrate from coking plants, a modified peanut shell biochar catalyst was developed that simultaneously removes intermediate methylaniline and indole from the concentrate. The preparation method is as follows:

[0060] 1) Raw material selection:

[0061] Peanut shells were used as biochar raw material. They were first rinsed three times with tap water, and a 1.2 mol / L sodium hydroxide solution was prepared. The peanut shells were soaked in the sodium hydroxide solution for 150 minutes, then removed and dried. They were then placed in a 105℃ oven for 4 hours and allowed to cool naturally.

[0062] 2), carbonization:

[0063] Peanut shells are placed in a muffle furnace and heated to 695℃ at a rate of 6℃ / min. The mixture is then pyrolyzed for 105 min and allowed to cool naturally to form peanut shell biochar. The peanut shell biochar is then ground into fine powder using a grinder and screened through a 100-mesh sieve.

[0064] 3) Biochar modification:

[0065] A 11% (calculated by metal element) manganese nitrate solution and a 7% ferric nitrate solution were prepared, and then these two solutions were mixed in a volume ratio of 2:1 and placed into a reaction vessel. In the reaction vessel, the mixture was heated to 83°C under nitrogen protection and aged at this temperature for 9 hours. After cooling, it was filtered, and the peanut shell biochar was washed five times with water and dried in an oven at 105°C for 4 hours. After cooling, a modified peanut shell biochar catalyst was formed.

[0066] The modified peanut shell biochar catalyst has a rough and porous surface, exhibiting good water absorption and ion exchange capabilities. Manganese and iron metals can be effectively supported on the surface of the modified peanut shell biochar catalyst. The specific surface area of ​​the prepared modified peanut shell biochar catalyst is 141.1 m². 2 / g, metal loading rate 7% (determined by gravimetric method). The prepared modified peanut shell biochar catalyst exhibits good physical properties and can effectively convert ozone into hydroxyl radicals, degrade and adsorb ozone in ozone catalytic oxidation reactions.

[0067] After ozone catalysis, the conductivity of the coking nanofiltration concentrate is 34560 μS / cm, the sulfate ion concentration is 1340 mg / L, the m-methylaniline concentration is 6 μg / L, and the indole concentration is 5 μg / L.

[0068] Subsequently, the drainage pump discharges the coking nanofiltration concentrate.

[0069] Example 2:

[0070] In this embodiment, the electrical conductivity of the coking nanofiltration concentrate is 21670 μS / cm, the sulfate ion concentration is 589 mg / L, the m-methylaniline concentration is 49 μg / L, and the indole concentration is 27 μg / L.

[0071] The concentrated wastewater from coking nanofiltration enters the ozone catalytic reaction tower via an inlet pump. The tower is equipped with a modified peanut shell biochar catalyst. The nanofiltration wastewater enters the tower from the bottom and flows out from the top. The ozone generator is an oxygen source generator; the generated ozone enters the catalytic tower from the bottom and fills the entire tower, achieving an ozone concentration of 90 g / m³. 3 The modified peanut shell biochar catalyst accounts for 80% of the total volume of the ozone catalytic tower, and the residence time of the nanofiltration concentrate in the tower is 30 minutes.

[0072] To address the high conductivity of nanofiltration concentrate from coking plants, a modified peanut shell biochar catalyst was developed that simultaneously removes intermediate methylaniline and indole from the concentrate. The preparation method is as follows:

[0073] 1) Raw material selection:

[0074] Peanut shells were used as biochar raw material. They were first rinsed three times with tap water, and a 0.4 mol / L sodium hydroxide solution was prepared. The peanut shells were soaked in the sodium hydroxide solution for 125 minutes, then removed and dried. They were then placed in a 105℃ oven for 2 hours and allowed to cool naturally.

[0075] 2), carbonization:

[0076] Peanut shells are placed in a muffle furnace and heated to 630℃ at a rate of 6℃ / min. The mixture is then pyrolyzed for 90 minutes and allowed to cool naturally to form peanut shell biochar. The peanut shell biochar is then ground into fine powder using a grinder and sieved through a 200-mesh screen.

[0077] 3) Biochar modification:

[0078] Prepare an 8% (based on metal element) manganese nitrate solution and a 6% ferric nitrate solution, then mix these two solutions at a volume ratio of 3:1 and place them into a reaction vessel. In the reaction vessel, heat to 83°C under nitrogen protection and age at this temperature for 7 hours. After cooling, filter the mixture. Wash the peanut shell biochar three times with water, dry it in a 105°C oven for 2 hours, and then cool to form a modified peanut shell biochar catalyst.

[0079] The modified peanut shell biochar catalyst has a rough and porous surface, exhibiting good water absorption and ion exchange capabilities. Manganese and iron metals can be effectively supported on the surface of the modified peanut shell biochar catalyst. The specific surface area of ​​the prepared modified peanut shell biochar catalyst is 127.3 m². 2 / g, metal loading rate 4% (determined by gravimetric method). The prepared modified peanut shell biochar catalyst exhibits good physical properties and can effectively convert ozone into hydroxyl radicals, degrade and adsorb ozone in ozone catalytic oxidation reactions.

[0080] After ozone catalysis, the conductivity of the coking nanofiltration concentrate is 21670 μS / cm, the sulfate ion concentration is 589 mg / L, the m-methylaniline concentration is 4 μg / L, and the indole concentration is 2 μg / L.

[0081] Subsequently, the drainage pump discharges the coking nanofiltration concentrate.

[0082] The technical solution proposed in this invention for removing methylaniline and indole from nanofiltration concentrate in coking plants systematically solves the problem of environmental pollution caused by reverse osmosis concentrate discharge. Therefore, this invention belongs to the category of green and environmentally friendly steel production processes, and has significant social and environmental benefits.

[0083] Of course, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Any modifications or variations of the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A process for removing intermediate-methylaniline and indole from coking nanofiltration concentrate, wherein the coking nanofiltration concentrate has the following water quality: conductivity 21300~34560 µS / cm, sulfate ion concentration 567~1340 mg / L, m-methylaniline 45~78 µg / L, and indole 23~39 µg / L; characterized in that, The processing steps include the following: The concentrated water from coking nanofiltration enters the ozone catalytic tower from the bottom and flows out from bottom to top. The ozone catalytic tower is filled with modified peanut shell biochar catalyst. The modified peanut shell biochar catalyst is prepared using the following method: 1) Raw material selection: Prepare a 0.4~1.2 mol / L sodium hydroxide solution. Using peanut shells as biochar raw material, soak the rinsed peanut shells in the sodium hydroxide solution for 125~150 min, remove them, air dry them, and then bake them for the first time, followed by natural cooling. 2) Carbonization: The peanut shells processed in step 1) are placed in a muffle furnace and heated to 620-695℃ at a rate of 6-9℃ / min. The mixture is then pyrolyzed for 90-105 min and allowed to cool naturally to form peanut shell biochar. The obtained peanut shell biochar was ground into fine powder and screened into 100-300 mesh peanut shell biochar fine powder; 3) Biochar modification: Based on the metal element, prepare a manganese nitrate solution with a concentration of 8-11% and an iron nitrate solution with a concentration of 4-7%, and then mix these two solutions in a volume ratio of (2-4):1 to form a mixed solution and put it into the reaction vessel; In the reactor, the mixture is heated to 78-83℃ under nitrogen protection and aged at a constant temperature for 7-9 hours. After cooling, it is filtered, the peanut shell biochar is washed with water, and then baked a second time. After cooling, it forms a modified peanut shell biochar catalyst. After ozone catalysis, the electrical conductivity of the coking nanofiltration concentrate is 21300~34560 µS / cm, the sulfate ion concentration is 567~1340 mg / L, the m-methylaniline concentration is 3~7 µg / L, and the indole concentration is 1~6 µg / L.

2. The process for removing intermediate methylaniline and indole from coking nanofiltration concentrate according to claim 1, characterized in that, The ozone generator in the ozone catalytic tower is an oxygen source generator. The generated ozone enters the ozone catalytic tower from the bottom and then fills the entire catalytic tower, with an ozone concentration of 90~105 g / m³. 3 .

3. The process for removing intermediate methylaniline and indole from coking nanofiltration concentrate according to claim 1 or 2, characterized in that, The modified peanut shell biochar catalyst accounts for 75-85% of the total volume of the ozone catalytic tower, and the residence time of nanofiltration concentrate in the ozone catalytic tower is 27-46 min.

4. The process for removing intermediate methylaniline and indole from coking nanofiltration concentrate according to claim 1, characterized in that, The first baking is carried out in an oven at 105℃ for 2-4 hours; the second baking is carried out in an oven at 105℃ for 2-4 hours.

5. An apparatus for implementing the process described in any one of claims 1-4, characterized in that, The device includes an ozone generating tower, the bottom of which is connected to an inlet pipe for the nanofiltration concentrate to be treated, and the top or upper part of which is connected to an outlet pipe. The bottom of the ozone generating tower is also connected to an ozone inlet pipe for introducing ozone, which is connected to an external ozone generator. Modified peanut shell biochar catalyst is installed inside the ozone generating tower.

6. The device according to claim 5, characterized in that, The ozone concentration inside the ozone catalytic tower is 90~105 g / m³. 3 The modified peanut shell biochar catalyst accounts for 75-85% of the total volume of the ozone catalytic tower.

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