Method for treating wastewater from nitrochlorobenzene production

Abstract

The application discloses a wastewater treatment method for nitrochlorobenzene production and belongs to the technical field of organic chemical wastewater treatment. The treatment method comprises the following steps: wastewater is self-flowed into a pretreatment tank and is layered by standing, upper-layer wastewater is treated by using adsorption resin to obtain desorption liquid, catalyst and potassium persulfate are added into the desorption liquid, stirring and filtering are carried out, and treatment liquid is obtained, and the treatment liquid is discharged after being detected to be qualified. In the application, sulfate radicals are used as main active molecules to treat phenolic substances. In order to improve the treatment efficiency, the application prepares a catalyst. The catalyst prepared by the application is prepared by loading active substances on a carrier. The carrier is a diatomite-based carrier with high porosity and strong catalytic performance. The main component of the active substances is magnetic nano CoFe2O4 particles. The wastewater treatment method for nitrochlorobenzene production disclosed by the application can significantly reduce the content of nitrochlorobenzene and the total phenol content in wastewater.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical wastewater treatment technology, specifically relating to a method for treating wastewater from nitrochlorobenzene production. Background Technology

[0002] Nitrochlorobenzenes are a class of chlorinated, nitro-containing aromatic hydrocarbon compounds widely used as intermediates in the production of pharmaceuticals, dyes, and pesticides. However, the production of nitrochlorobenzenes generates large amounts of wastewater with high organic content, including nitrochlorobenzene, nitrochlorophenol, and nitrophenol. Nitrochlorobenzene is present in the largest quantity and is also highly toxic. It can be absorbed into the human body through the skin, and its vapors can enter the body through the respiratory tract, damaging the hematopoietic and nervous systems and causing poisoning. Therefore, the pollution problem of nitrochlorobenzene production wastewater and its environmental fate are receiving increasing attention.

[0003] Chinese patent CN1233570C discloses a resin adsorption recovery process for nitrochlorobenzene from nitrochlorobenzene production wastewater. This process utilizes the different adsorption affinities between nitrochlorobenzene and nitrophenolic substances in the wastewater and the adsorption resin. The resin is used as an adsorbent to selectively adsorb ortho- and para-nitrochlorobenzene from the wastewater, while nitrophenolic substances are not adsorbed. This patent effectively separates nitrochlorobenzene from the wastewater, but the nitrophenolic substances still require further treatment. Summary of the Invention

[0004] Based on existing technology, this invention improves the treatment method for wastewater from nitrochlorobenzene production, thereby achieving comprehensive wastewater treatment.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for treating wastewater from nitrochlorobenzene production includes the following steps:

[0007] Wastewater flows into a pretreatment tank by gravity and is allowed to settle and separate into layers. The upper layer of wastewater is treated by adsorption resin to obtain desorbed liquid. Catalyst and potassium persulfate are added to the desorbed liquid, and the mixture is stirred and filtered to obtain treated liquid. The treated liquid is discharged after passing the test. Treated liquid that does not meet the standard is introduced into the pretreatment tank for recycling.

[0008] Furthermore, the adsorption resin is NDA-150 type styrene-divinylbenzene adsorption resin.

[0009] Furthermore, the ratio of the desorption solution, catalyst, and potassium persulfate is 100 mL: 0.15-0.16 g: 2.4 mmol.

[0010] Furthermore, the preparation process of the catalyst is as follows:

[0011] Step S1: Cobalt nitrate hexahydrate and ferric nitrate nonahydrate are added to deionized water with stirring. The temperature is raised to 80°C and stirred for 2 hours. Citric acid is added dropwise and the mixture is stirred for 2 hours to obtain the active substance.

[0012] Step S2: Add NaOH and β-cyclodextrin to deionized water and stir for 30 min. Heat to 30°C and add epichlorohydrin. Stir for 2 h. Add Tween-20, kerosene and diatomaceous earth and continue stirring for 30 min. Heat to 65-70°C and stir for 8-10 h. Filter, wash and dry to obtain the support.

[0013] Step S3: Add the active material to the carrier and heat to 60°C. Stir and mix for 2 hours to obtain a sol. Dry the sol for 6-12 hours to obtain a precursor. Grind the precursor into powder and place it in a muffle furnace. Calcinate at 600°C for 2 hours. After calcination, cool to room temperature to obtain the catalyst.

[0014] Furthermore, in step S1, the ratio of deionized water, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, and citric acid is 500 mL: 1 mol: 2.0-2.1 mol: 3 mol.

[0015] Further, in step S2, the ratio of deionized water, NaOH, β-cyclodextrin, epichlorohydrin, Tween-20, kerosene, and diatomaceous earth is 200mL:30g:100g:10.8-11.0mL:12-13g:150mL:5.7-6.0g.

[0016] Furthermore, in step S3, the ratio of the carrier to the active substance is 100g: 50-70mL.

[0017] The beneficial effects of this invention are:

[0018] This invention discloses a method for treating wastewater from nitrochlorobenzene production, which can significantly reduce the content of nitrochlorobenzene and total phenol in the wastewater (nitrochlorobenzene ≤ 30 mg / L; total phenol ≤ 10 mg / L). This invention achieves comprehensive wastewater treatment by improving the treatment method for wastewater from nitrochlorobenzene production.

[0019] This invention utilizes adsorption resin to remove nitrochlorobenzene, and then uses sulfate radicals as the main active molecules to treat phenolic substances in wastewater. The total phenol content in the wastewater is reduced through advanced oxidation processes (AOPs). In order to promote the oxidation efficiency of AOPs and generate sulfate radicals from persulfate, this invention prepares a catalyst.

[0020] The catalyst prepared in this invention is made by supporting active materials on a support. The support is a diatomaceous earth-based support with high porosity and strong catalytic performance. The main component of the active material is magnetic nano-CoFe2O4 particles, which are activated by transition metals to remove sulfates. Then, this invention uses emulsion polymerization to load β-cyclodextrin onto the surface of diatomaceous earth through hydrogen bonding. The surface of β-cyclodextrin contains a large number of active hydroxyl groups. Therefore, β-cyclodextrin acts as a "bridge," which helps to improve the interaction between the active material and the support, thereby enhancing the adsorption performance of the active material and diatomaceous earth. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] The main components and their contents in the nitrochlorobenzene production wastewater within this plant area:

[0023]

[0024] Example 1

[0025] Preparation of catalysts:

[0026] Preparation of active material: 500 mL of deionized water was added to reactor A, and then 1 mol of cobalt nitrate hexahydrate (Co(NO3)2-6H2O) and 2.0 mol of ferric nitrate nonahydrate (Fe(NO3)3-9H2O) were added to the reactor with stirring. The reactor A was heated to 80 °C and stirred for 2 h. Then 3 mol of citric acid was added dropwise and the mixture was stirred and reacted for another 2 h to obtain the active material. The main component of the active material is magnetic nano-CoFe2O4 particles.

[0027] Preparation of the carrier: 200 mL of deionized water was added to reactor B, followed by the addition of 30 g of NaOH and 100 g of β-cyclodextrin. The mixture was stirred for 30 min, and reactor B was heated to 30 °C. 10.8 mL of epichlorohydrin was added, and the mixture was stirred for 2 h. Then, 12 g of emulsifier Tween-20, 150 mL of kerosene, and 5.7 g of diatomaceous earth were added to reactor B. The mixture was stirred for another 30 min, and reactor B was heated to 65 °C. The mixture was stirred for 8 h, filtered, washed, and dried to obtain the carrier. β-cyclodextrin was loaded onto the surface of diatomaceous earth via emulsion polymerization to prepare a carrier with abundant hydroxyl groups.

[0028] Carrier preparation: 100g of carrier was added to reactor C, and then 50mL of active material was added while stirring. Reactor C was heated to 60℃ and stirred for 2h to obtain a sol. The sol was transferred to a 90℃ constant temperature drying oven and dried for 6h to obtain a precursor. The precursor was ground into powder, placed in a ceramic crucible, and then placed in a muffle furnace and calcined at 600℃ for 2h. After calcination, it was cooled to room temperature to obtain the catalyst.

[0029] Example 2

[0030] Preparation of catalysts:

[0031] Preparation of active material: 500 mL of deionized water was added to reactor A, and then 1 mol of cobalt nitrate hexahydrate (Co(NO3)2-6H2O) and 2.1 mol of ferric nitrate nonahydrate (Fe(NO3)3-9H2O) were added to the reactor while stirring. The reactor A was heated to 80 °C and stirred for 2 h. Then, 3 mol of citric acid was added dropwise and the mixture was stirred and reacted for another 2 h to obtain the active material. The main component of the active material is magnetic nano-CoFe2O4 particles.

[0032] Preparation of the carrier: 200 mL of deionized water was added to reactor B, followed by the addition of 30 g of NaOH and 100 g of β-cyclodextrin. The mixture was stirred for 30 min, and reactor B was heated to 30 °C. 10.9 mL of epichlorohydrin was added, and the mixture was stirred for 2 h. Then, 12.5 g of emulsifier Tween-20, 150 mL of kerosene, and 5.8 g of diatomaceous earth were added to reactor B. The mixture was stirred for another 30 min, and reactor B was heated to 68 °C. The mixture was stirred for 9 h, filtered, washed, and dried to obtain the carrier. β-cyclodextrin was loaded onto the surface of diatomaceous earth via emulsion polymerization to prepare a carrier with abundant hydroxyl groups.

[0033] Carrier preparation: 100g of carrier was added to reactor C, and then 60mL of active material was added while stirring. Reactor C was heated to 60℃ and stirred for 2h to obtain a sol. The sol was transferred to a 90℃ constant temperature drying oven and dried for 10h to obtain a precursor. The precursor was ground into powder, placed in a ceramic crucible, and then placed in a muffle furnace and calcined at 600℃ for 2h. After calcination, it was cooled to room temperature to obtain the catalyst.

[0034] Example 3

[0035] Preparation of catalysts:

[0036] Preparation of active material: 500 mL of deionized water was added to reactor A, and then 1 mol of cobalt nitrate hexahydrate (Co(NO3)2-6H2O) and 2.1 mol of ferric nitrate nonahydrate (Fe(NO3)3-9H2O) were added to the reactor while stirring. The reactor A was heated to 80 °C and stirred for 2 h. Then, 3 mol of citric acid was added dropwise and the mixture was stirred and reacted for another 2 h to obtain the active material. The main component of the active material is magnetic nano-CoFe2O4 particles.

[0037] Preparation of the carrier: 200 mL of deionized water was added to reactor B, followed by the addition of 30 g of NaOH and 100 g of β-cyclodextrin. The mixture was stirred for 30 min, and reactor B was heated to 30 °C. 11.0 mL of epichlorohydrin was added, and the mixture was stirred for 2 h. Then, 13 g of emulsifier Tween-20, 150 mL of kerosene, and 6.0 g of diatomaceous earth were added to reactor B. The mixture was stirred for another 30 min, and reactor B was heated to 70 °C. The mixture was stirred for 10 h, filtered, washed, and dried to obtain the carrier. β-cyclodextrin was loaded onto the surface of diatomaceous earth via emulsion polymerization to prepare a carrier with abundant hydroxyl groups.

[0038] Carrier preparation: 100g of carrier was added to reactor C, and then 70mL of active material was added while stirring. Reactor C was heated to 60℃ and stirred for 2h to obtain a sol. The sol was transferred to a 90℃ constant temperature drying oven and dried for 12h to obtain a precursor. The precursor was ground into powder, placed in a ceramic crucible, and then placed in a muffle furnace and calcined at 600℃ for 2h. After calcination, it was cooled to room temperature to obtain the catalyst.

[0039] Example 4

[0040] A method for treating wastewater from nitrochlorobenzene production includes the following steps:

[0041] Wastewater flows by gravity into a pretreatment tank for sedimentation and stratification. The contents of nitrochlorobenzene, nitrochlorophenol, and nitrophenol in the wastewater are measured. The upper layer of wastewater is then introduced into an adsorption tower loaded with NDA-150 styrene-divinylbenzene adsorption resin. The resin undergoes thermal desorption and regeneration using 120°C steam. The flow rate of the upper wastewater through the resin is 10 BV / h. The adsorption tower is used to remove nitrochlorobenzene. After adsorption treatment, a desorbed liquid is obtained and introduced into a storage tank. The contents of nitrochlorobenzene and nitrophenol in the desorbed liquid are measured. The content of chlorophenol and nitrophenol was determined, and then the catalyst prepared in Example 1 and potassium persulfate were added to the water storage tank for chemical treatment of phenol-containing wastewater. After stirring for 2 hours, the mixture was filtered to obtain a treated liquid. The ratio of desorption liquid, catalyst and potassium persulfate was 100 mL: 0.15 g: 2.4 mmol. The treated liquid was discharged after passing the test. The treated liquid that did not meet the standard was introduced into the pretreatment tank for circulation treatment. The standard for passing the test of the treated liquid was: nitrochlorophenol ≤ 30 mg / L; total phenol content ≤ 10 mg / L; color ≤ 30 times.

[0042] Example 5

[0043] A method for treating wastewater from nitrochlorobenzene production includes the following steps:

[0044] Wastewater flows by gravity into a pretreatment tank for sedimentation and stratification. The contents of nitrochlorobenzene, nitrochlorophenol, and nitrophenol in the wastewater are measured. The upper layer of wastewater is then introduced into an adsorption tower loaded with NDA-150 styrene-divinylbenzene adsorption resin. The resin undergoes thermal desorption and regeneration using 130°C steam. The flow rate of the upper wastewater through the resin is 10 BV / h. The adsorption tower is used to remove nitrochlorobenzene. After adsorption treatment, a desorbed liquid is obtained and introduced into a storage tank. The contents of nitrochlorobenzene and nitrophenol in the desorbed liquid are measured. The content of chlorophenol and nitrophenol was determined, and then the catalyst prepared in Example 2 and potassium persulfate were added to the water storage tank for chemical treatment of phenol-containing wastewater. After stirring for 3 hours, the mixture was filtered to obtain a treated liquid. The ratio of desorption liquid, catalyst and potassium persulfate was 100 mL: 0.16 g: 2.4 mmol. The treated liquid was discharged after passing the test. The treated liquid that did not meet the standard was introduced into the pretreatment tank for circulation treatment. The standard for passing the test of the treated liquid was: nitrochlorophenol ≤ 30 mg / L; total phenol content ≤ 10 mg / L; color ≤ 30 times.

[0045] Example 6

[0046] A method for treating wastewater from nitrochlorobenzene production includes the following steps:

[0047] Wastewater flows by gravity into a pretreatment tank for sedimentation and stratification. The contents of nitrochlorobenzene, nitrochlorophenol, and nitrophenol in the wastewater are measured. The upper layer of wastewater is then introduced into an adsorption tower loaded with NDA-150 styrene-divinylbenzene adsorption resin. The resin undergoes thermal desorption and regeneration using 140°C steam. The flow rate of the upper wastewater through the resin is 10 BV / h. The adsorption tower is used to remove nitrochlorobenzene. After adsorption treatment, a desorbed liquid is obtained and introduced into a storage tank. The contents of nitrochlorobenzene and nitrophenol in the desorbed liquid are measured. The content of chlorophenol and nitrophenol was determined, and then the catalyst prepared in Example 3 and potassium persulfate were added to the water storage tank for chemical treatment of phenol-containing wastewater. After stirring for 4 hours, the mixture was filtered to obtain a treated liquid. The ratio of desorption liquid, catalyst and potassium persulfate was 100 mL: 0.16 g: 2.4 mmol. The treated liquid was discharged after passing the test. The treated liquid that did not meet the standard was introduced into the pretreatment tank for circulation treatment. The standard for passing the test of the treated liquid was: nitrochlorophenol ≤ 30 mg / L; total phenol content ≤ 10 mg / L; color ≤ 30 times.

[0048] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for treating wastewater from the production of nitrochlorobenzene, characterized in that, Includes the following steps: Wastewater flows into the pretreatment tank by gravity and is allowed to stand and separate into layers. The upper layer of wastewater is treated by adsorption resin to obtain desorption liquid. Catalyst and potassium persulfate are added to the desorption liquid, and the mixture is stirred and filtered to obtain treated liquid. The treated liquid is discharged after passing the test. The treated liquid that does not meet the standard is introduced into the pretreatment tank for recycling. The preparation process of the catalyst: Step S1: Cobalt nitrate hexahydrate and ferric nitrate nonahydrate are added to deionized water with stirring. The temperature is raised to 80°C and stirred for 2 hours. Citric acid is added dropwise and the mixture is stirred for 2 hours to obtain the active substance. Step S2: Add NaOH and β-cyclodextrin to deionized water and stir for 30 min. Heat to 30°C, add epichlorohydrin, and stir for 2 h. Add Tween-20, kerosene and diatomaceous earth, and continue stirring for 30 min. Heat to 65-70°C and stir for 8-10 h. Filter, wash and dry to obtain the carrier. Step S3: Add the active material to the carrier and heat to 60°C. Stir and mix for 2 hours to obtain a sol. Dry the sol for 6-12 hours to obtain a precursor. Grind the precursor into powder and place it in a muffle furnace. Calcinate at 600°C for 2 hours. After calcination, cool to room temperature to obtain the catalyst.

2. The method for treating wastewater from nitrochlorobenzene production according to claim 1, characterized in that, The adsorption resin is NDA-150 type styrene-divinylbenzene adsorption resin.

3. The method for treating wastewater from nitrochlorobenzene production according to claim 1, characterized in that, The ratio of the desorption solution, catalyst, and potassium persulfate is 100 mL: 0.15-0.16 g: 2.4 mmol.

4. The method for treating wastewater from nitrochlorobenzene production according to claim 1, characterized in that, The ratio of deionized water, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, and citric acid used in step S1 is 500 mL: 1 mol: 2.0-2.1 mol: 3 mol.

5. The method for treating wastewater from nitrochlorobenzene production according to claim 1, characterized in that, The ratio of deionized water, NaOH, β-cyclodextrin, epichlorohydrin, Tween-20, kerosene, and diatomaceous earth used in step S2 is 200mL:30g:100g:10.8-11.0mL:12-13g:150mL:5.7-6.0g.

6. The method for treating wastewater from nitrochlorobenzene production according to claim 1, characterized in that, The ratio of carrier to active substance in step S3 is 100g: 50-70mL.

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