Coal chemical high-salinity wastewater treatment process

Abstract

The application discloses a coal chemical high-salinity wastewater treatment process and belongs to the technical field of water treatment; the application adopts a pretreatment, deep oxidation, desalination and sterilization integrated treatment scheme, and the core advantage lies in that the organic matter degradation and salt removal can be efficiently considered. The deep oxidation adopts a new rare earth-based high-entropy composite Janus structure nanoparticle catalyst, a cooling crystallization strategy based on carbon affinity difference guidance, electrospinning, graphitization and interface regulation, and realizes two-phase directional growth and heterogeneous integration. The asymmetric structure of the Janus material endows it with unique hydrophilic-hydrophobic wettability, can efficiently deal with the challenges of complex composition, oil stains and surfactants in the coal chemical high-salinity wastewater, and can effectively resist the erosion of high salt, high temperature and high pressure working conditions due to the stable single crystal phase formed by multiple metal elements, and can synergistically improve the COD removal efficiency of the ozone catalytic process; after the deep oxidation, the wastewater is subjected to multi-effect evaporation desalination, activated carbon adsorption and ultraviolet sterilization, and water meeting the discharge standard is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a coal chemical high-salinity wastewater treatment process. BACKGROUND

[0002] Coal chemical high-salinity wastewater is one of the key pollution sources generated in the production process of the coal chemical industry, and has the characteristics of complex water quality and difficult treatment. The wastewater has extremely high salt content, with TDS (total dissolved solids) usually exceeding 10,000 mg / L, and even reaching more than 50,000 mg / L; the pollutant composition is complex, containing toxic and harmful substances such as phenols, cyanide, polycyclic aromatic hydrocarbons and heterocyclic compounds; at the same time, the COD (chemical oxygen demand) is generally higher than 1,000 mg / L, and the biodegradability is poor, with a B / C ratio of less than 0.2.

[0003] Since conventional biochemical treatment cannot directly degrade this type of wastewater, and physical adsorption and membrane separation technologies cannot completely remove organic pollutants, ozone catalytic oxidation technology has become one of the key technologies for treating such high-salinity wastewater, as it can efficiently decompose refractory organic matter and significantly improve the biodegradability of wastewater.

[0004] A coal chemical wastewater treatment process is disclosed in Chinese Patent No. CN106116011B. The invention first treats the organic wastewater in coal chemical wastewater by a deaminated phenol treatment process, then by biochemical treatment, followed by concentration treatment, and finally by concentrated brine treatment to obtain salt-containing materials. The deaminated phenol treatment process includes a deacidification and deamination process, an extraction process, a solvent removal process, a solvent recovery process, a waste liquid separation system, a solvent storage process, and an alkali preparation process. This scheme realizes zero discharge of sewage through separate treatment and cascade reuse. However, under the premise that the process design relies on the classification treatment of organic wastewater and salt-containing wastewater, if the actual water conditions deviate from the design assumptions, it is easy to lead to a decrease in treatment efficiency. The deaminated phenol treatment process has a high removal rate for single phenols, but coal chemical wastewater often contains multiple phenols, heterocyclic organic matter such as naphthol and pyridine, and other substances. These substances are difficult to be effectively extracted by conventional extraction solvents, resulting in COD of the waste liquid after deaminated phenol treatment still being >1,000 mg / L, and subsequent biochemical treatment load increasing sharply, leading to problems such as sludge bulking and non-compliance of effluent. SUMMARY

[0005] In order to improve the efficiency of ozone catalysts in removing COD in high-salinity wastewater, the present application proposes a new solution to adapt to different production processes and application environments.

[0006] The present application aims to provide a coal chemical high-salinity wastewater treatment process. The technical scheme first filters the wastewater to remove large-particle impurities, protects the pump body and equipment used in the subsequent process, adds a coagulant for flocculation, and the filtered wastewater enters an oxidation tank, uses a new type of oxidant for catalytic oxidation with ozone, degrades complex organic matter in the wastewater, and finally enters a multi-effect evaporation tank for desalination. The condensed water is finally subjected to activated carbon adsorption and ultraviolet sterilization to kill microorganisms and prevent the growth of biological sludge in the pipeline. Ultimately, water that meets the discharge standard is obtained. The new catalyst used in the present application is a rare earth-based high-entropy composite Janus structure nanoparticle catalyst (rare earth-based high-entropy composite asymmetric amphiphilic catalyst). A high-entropy precursor solution is prepared by mixing cerium salt, europium salt, tungsten salt, and other metal salts with PAN (polyacrylonitrile), a nanofiber membrane is obtained by electrospinning, and the rare earth-based high-entropy composite Janus structure nanoparticle catalyst is obtained by graphitization treatment. The Janus structure has one hydrophilic side and one hydrophobic side, which enables it to effectively address the challenges of complex composition, high salinity, oil contamination, and surfactants in coal chemical high-salinity wastewater, and enhances its adaptability and treatment effect in complex water quality environments.

[0007] To achieve the above-mentioned purpose, the present application provides a coal chemical high-salinity wastewater treatment process, comprising:

[0008] S1, start the wastewater lifting pump, control the water inflow to make the wastewater uniformly enter the vibrating screen, and the filtered wastewater enters the sedimentation tank;

[0009] S2, adjust the pH of the wastewater to 6.5-7.5, add a coagulant under stirring, promote flocculation by stirring, and let it stand. The filtered wastewater enters the oxidation tank;

[0010] S3, add the rare earth-based high-entropy composite Janus structure nanoparticle catalyst to the oxidation tank, catalytically oxidize and degrade pollutants in cooperation with ozone, and the filtered wastewater enters the evaporation tank;

[0011] S4, the wastewater is desalted by multi-effect evaporation, the condensed water is adsorbed by activated carbon, enters the ultraviolet reactor for ultraviolet sterilization, and is filtered to obtain dischargeable water that meets the standard.

[0012] The present application also provides a preparation method of the rare earth-based high-entropy composite Janus structure nanoparticle catalyst described in S3, comprising:

[0013] A1, add cerium salt, europium salt, tungsten salt, manganese salt, other metal salt, and PAN to DMF (N,N-dimethylformamide), stir to obtain a high-entropy precursor solution, and the other metal salt is iron salt or cobalt salt;

[0014] A2, the high-entropy precursor solution is electrospun and dried to obtain a nanofiber membrane;

[0015] A3, placing the nanofiber membrane in a chemical vapor deposition furnace for graphitization treatment: heating in an air atmosphere, switching to an argon atmosphere, holding, cooling and crystallizing to obtain a rare earth-based high-entropy composite Janus structure nanoparticle catalyst.

[0016] Preferably, in A1, the cerium salt is Ce(NO3)3·6H2O.

[0017] Preferably, in A1, the europium salt is Eu(NO3)3·6H2O.

[0018] Preferably, in A1, the tungsten salt is (NH4)6H2W 12 O 40 .

[0019] Preferably, in A1, the manganese salt is Mn(OAc)2·4H2O.

[0020] Preferably, in A1, the iron salt is Fe(NO3)3·9H2O.

[0021] Preferably, in A1, the cobalt salt is Co(NO3)2·6H2O.

[0022] Preferably, in A1, the mass-volume ratio of the cerium salt, the europium salt, the tungsten salt, the manganese salt, Fe(NO3)3·9H2O, PAN and DMF is (80-180) mg:(60-120) mg:(40-70) mg:(20-60) mg:(60-120) mg:(1.2-1.9) g:15 mL.

[0023] Preferably, in A1, the mass-volume ratio of the cerium salt, the europium salt, the tungsten salt, the manganese salt, Co(NO3)2·6H2O, PAN and DMF is (80-180) mg:(60-120) mg:(40-70) mg:(20-60) mg:(60-90) mg:(1.2-1.9) g:15 mL.

[0024] Preferably, in A1, the stirring time is 10-12 h.

[0025] Preferably, in A2, the process parameters of electrospinning are: an anode voltage of 15-16 kV, a cathode voltage of 1-2 kV, and a needle tip-tin foil collector distance of 15-20 cm; the drying temperature is 50-60℃, and the drying time is 10-12 h.

[0026] Preferably, in A3, the heating temperature is 200-230℃, and the heating time is 3-4 h.

[0027] Preferably, in the A3, the temperature of the heat preservation is 800-1000℃, the time of the heat preservation is 3-5h, and the heating rate is 2℃ / min.

[0028] Preferably, in the A3, the temperature of the cooling crystallization is 600-700℃, and the cooling rate is 2℃ / min.

[0029] Preferably, in the S1, the water flow rate is 80-100m 3 / h, and the pressure is controlled at 0.2-0.4MPa.

[0030] Preferably, in the S1, the aperture of the vibrating screen is 100-200 mesh, the frequency is controlled at 1500-3000 times / min, and the amplitude is 3-5mm.

[0031] Preferably, in the S2, the coagulant is a polyaluminum chloride aqueous solution with a concentration of 10-15wt.%, and the addition amount of the coagulant is 100-200mg / L of wastewater.

[0032] Preferably, in the S2, the stirring speed is 200-300rpm, and the stirring time is 2-5min.

[0033] Preferably, in the S2, the stirring speed for promoting flocculation is 50-80rpm, and the time is 5-10min.

[0034] Preferably, in the S2, the standing time is 30-60min.

[0035] Preferably, in the S3, the catalyst is a rare earth-based high-entropy composite Janus structure nanoparticle catalyst.

[0036] Preferably, in the S3, the amount of the catalyst is (8-10)g / L of wastewater.

[0037] Preferably, in the S4, the process and parameters of the multi-effect evaporation desalination include: the heating steam temperature of the first-effect evaporation is 120-130℃, the operating pressure is 0.15-0.2MPa, the heating steam temperature of the second-effect evaporation is 100-110℃, the operating pressure is 0.08-0.1MPa, and the heating steam temperature of the third-effect evaporation is 85-95℃, the operating pressure is 0.03-0.05MPa.

[0038] Preferably, in the S4, the process and parameters of the activated carbon adsorption include: a fixed bed activated carbon adsorption column is used, the activated carbon is granular coconut shell activated carbon, the specific surface area is ≥1000m 2 / g, the pore size is 2-5nm, the flow rate of the wastewater into the activated carbon adsorption column is 5-8m / h, and the residence time is 15-20min.

[0039] Preferably, in the S4, the parameters of the ultraviolet reactor are: the wavelength of the ultraviolet lamp is 254 nm, and the irradiation amount is 20-30 mJ / cm 2 The flow rate of the wastewater in the ultraviolet reactor is 1-2 m / s.

[0040] Compared with the prior art, the beneficial effects of the present application are embodied in:

[0041] (1) The present application uses a rare earth-based high-entropy composite Janus structure nanoparticle catalyst in the wastewater oxidation process stage, which cooperates with ozone catalytic oxidation to improve the wastewater treatment efficiency. The rare earth elements, with their unique electronic structure and excellent oxygen storage capacity, combined with the synergistic effect brought by high-entropy effect, can significantly reduce the reaction activation energy and the required temperature in the process of catalytic oxidation degradation of organic matter. At the same time, the rare earth component also has certain resistance to sulfur and halogen poisoning performance, which can effectively disperse and passivate the toxic substances in the wastewater, and improve the stability of the catalyst; the nanoscale catalyst has a stable single crystal structure composed of multiple metal elements, which endows the catalyst with excellent corrosion resistance, enabling it to better resist the erosion caused by complex components in high-salinity wastewater and high-temperature and high-pressure process conditions, thereby delaying the catalyst deactivation process; by utilizing the carbonophilic difference to induce W2C preferential nucleation, and driving the catalyst epitaxial growth in the subsequent cooling process, a functional material with Janus structure is finally formed. The structure is hydrophilic on one side and hydrophobic on the other side, which can effectively deal with the challenges of complex composition, high salinity, oil stains and surfactants in coal chemical high-salinity wastewater, and enhance its adaptability and treatment effect in complex water environment.

[0042] (2) The present application adopts a pretreatment, advanced oxidation, desalination and sterilization integrated treatment scheme for high-salinity and high-organic wastewater, and the core advantage is that it can efficiently consider organic matter degradation and salt removal. In the pretreatment stage, a vibrating screen and a coagulant are used to efficiently remove suspended solids and colloids, in the advanced oxidation stage, a new type of rare earth-based high-entropy composite Janus structure nanoparticle catalyst and ozone are used to synergistically degrade refractory organic matter, and in the desalination and sterilization stage, multi-effect evaporation, activated carbon adsorption and ultraviolet sterilization are used to realize dual control of salt and microorganisms, and simultaneously solve the problems of water salinization caused by salt residue and environmental risk caused by excessive microorganisms. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is a coal chemical high-salinity wastewater treatment process flow.

[0044] Figure 2 It is a preparation flow chart of a rare earth-based high-entropy composite Janus structure nanoparticle catalyst.

[0045] Figure 3COD removal rate of wastewater in Example 4~Example 6 and Comparative Example 3~Comparative Example 4.

[0046] Figure 4 Color removal rate of wastewater in Example 4~Example 6 and Comparative Example 3~Comparative Example 4.

[0047] Figure 5 TEM image of the rare earth-based high-entropy composite Janus structure nanoparticle catalyst prepared in Example 3. DETAILED DESCRIPTION

[0048] The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0049] The compounds used in the examples and comparative examples are all commercially available and are not subjected to any further purification treatment.

[0050] Example 1

[0051] As shown in Figure 2 , a rare earth-based high-entropy composite Janus structure nanoparticle catalyst, the preparation method thereof comprises:

[0052] A1, 86.85 mg of Ce (NO3)3·6H2O, 89.22 mg of Eu (NO3)3·6H2O, 49.27 mg of (NH4)6H2W 12 O 40 , 49.02 mg of Mn (OAc)2·4H2O, 80.60 mg of Fe (NO3)3·9H2O and 1.5 g of PAN are added to 15 mL of DMF, stirred at room temperature for 10 h, to obtain a high-entropy precursor solution.

[0053] A2, the high-entropy precursor solution is transferred to a syringe and fixed in an electrospinning device, the anode voltage is set to 15 kV, the cathode voltage is set to 1 kV, the needle tip-tin foil collector distance is set to 15 cm, and the electrospinning is continuously carried out for 10 h, to collect a nanofiber membrane, which is dried at 50℃ for 12 h, to obtain the nanofiber membrane.

[0054] A3, the nanofiber membrane is placed in a chemical vapor deposition furnace for graphitization treatment: in an air atmosphere, heated at 200℃ for 4 h to pre-oxidize the nanofiber membrane, switched to an argon atmosphere, heated from 200℃ to 800℃ at a rate of 2℃ / min, kept at 800℃ for 5 h, cooled to 600℃ at a rate of 2℃ / min, and cooled and crystallized to obtain the rare earth-based high-entropy composite Janus structure nanoparticle catalyst.

[0055] Example 2

[0056] As shown in Figure 2As shown, a rare earth-based high-entropy composite Janus structure nanoparticle catalyst is prepared by the following method:

[0057] A1. 86.85 mg of Ce(NO3)3·6H2O, 89.22 mg of Eu(NO3)3·6H2O, and 49.27 mg of (NH4)6H2W 12 O 40 49.02 mg of Mn(OAc)2·4H2O, 70.61 mg of Co(NO3)2·6H2O and 1.5 g of PAN were added to 15 mL of DMF and stirred at room temperature for 11 h to obtain a high-entropy precursor solution.

[0058] A2. The high-entropy precursor solution was transferred into a syringe and fixed in an electrospinning device. The anode voltage was set to 16kV, the cathode voltage to 2kV, and the distance between the needle tip and the tin foil collector to 18cm. Electrospinning was carried out continuously for 10h to collect the nanofiber membrane. The membrane was dried at 55℃ for 11h to obtain the nanofiber membrane.

[0059] A3. The nanofiber membrane was graphitized in a chemical vapor deposition furnace: the nanofiber membrane was pre-oxidized by heating at 220°C for 3 hours in an air atmosphere, then switched to an argon atmosphere and heated from 220°C to 900°C at a rate of 2°C / min, held for 4 hours, and then cooled to 600°C at a rate of 2°C / min. After cooling and crystallization, a rare earth-based high-entropy composite Janus structure nanoparticle catalyst was obtained.

[0060] Example 3

[0061] like Figure 2 As shown, a rare earth-based high-entropy composite Janus structure nanoparticle catalyst is prepared by the following method:

[0062] A1. 151.99 mg of Ce(NO3)3·6H2O, 66.91 mg of Eu(NO3)3·6H2O, and 49.27 mg of (NH4)6H2W 12 O 40 24.51 mg of Mn(OAc)2·4H2O, 70.61 mg of Co(NO3)2·6H2O and 1.5 g of PAN were added to 15 mL of DMF and stirred at room temperature for 12 h to obtain a high-entropy precursor solution.

[0063] A2. The high-entropy precursor solution was transferred into a syringe and fixed in an electrospinning apparatus. The anode voltage was set to 16kV, the cathode voltage to 1.5kV, and the distance between the needle tip and the tin foil collector to 20cm. Electrospinning was carried out continuously for 10h to collect the nanofiber membrane. The membrane was dried at 60℃ for 10h to obtain the nanofiber membrane.

[0064] A3, the nanofiber membrane was placed in a chemical vapor deposition furnace for graphitization treatment: pre-oxidation of the nanofiber membrane was performed at 230°C for 3h under air atmosphere, the atmosphere was switched to argon, the temperature was raised from 230°C to 1000°C at a rate of 2°C / min, held for 3h, the temperature was lowered to 700°C at a rate of 2°C / min, and the crystal was cooled to obtain a rare earth-based high-entropy composite Janus structure nanoparticle catalyst, a TEM image of which is shown in Figure 5 .

[0065] Comparative Example 1

[0066] A rare earth-based high-entropy composite Janus structure nanoparticle catalyst, the difference between the preparation method and Example 3 is that no Ce(NO3)3·6H2O and Eu(NO3)3·6H2O are added in A1.

[0067] Comparative Example 2

[0068] A rare earth-based high-entropy composite Janus structure nanoparticle catalyst, the difference between the preparation method and Example 3 is that no graphitization treatment is performed in A3, but the nanofiber membrane is moved into a muffle furnace, and calcination is performed at 1000°C for 3h under air atmosphere.

[0069] Example 4

[0070] As shown in Figure 1 , a coal chemical high-salt wastewater treatment process, comprising:

[0071] S1, start the wastewater lifting pump, control the water inlet flow to keep at 80m 3 / h, pressure 0.2MPa, make the wastewater uniformly enter the vibrating screen with a pore size of 200 meshes, a frequency of 1500 times / min, and an amplitude of 5mm for filtration, and the filtered wastewater enters the sedimentation tank.

[0072] S2, adjust the pH of the wastewater to 6.5, add a polyaluminum chloride aqueous solution with a concentration of 10wt.% (the addition amount is 100mg / L of wastewater) under stirring at a speed of 200rpm, stir for 5min, stir for 10min at a speed of 50rpm to promote flocculation, and stand for 60min, and the filtered wastewater enters the oxidation tank.

[0073] S3, add the rare earth-based high-entropy composite Janus structure nanoparticle catalyst prepared in Example 1 (the amount is 8g / L of wastewater) to the oxidation tank, set the flow rate of the ozone generator to 0.5L / min, and perform ozone catalytic oxidation degradation of pollutants, and the filtered wastewater enters the evaporation tank.

[0074] S4. Wastewater undergoes first-effect evaporation at 120℃ and 0.15MPa, followed by second-effect evaporation at 100℃ and 0.08MPa, and finally third-effect evaporation at 85℃ and 0.03MPa. The condensate enters a fixed-bed activated carbon adsorption column at a flow rate of 5 m / h, remains for 15 min, and then enters a UV reactor at a flow rate of 1 m / s. The UV lamp irradiation is set to 20 mJ / cm². 2 Sterilization and filtration produce water that meets discharge standards.

[0075] Example 5

[0076] like Figure 1 As shown, a coal chemical high-salt wastewater treatment process includes:

[0077] S1. Start the wastewater booster pump and control the influent flow rate to maintain 90 m³ / h. 3 The wastewater is filtered at a pressure of 0.3 MPa and a pore size of 100 mesh, a frequency of 2000 times / min, and an amplitude of 4 mm. After filtration, the wastewater enters a sedimentation tank.

[0078] S2. Adjust the pH of the wastewater to 7, add a 15wt.% polyaluminum chloride aqueous solution (addition amount is 150mg / L wastewater) while stirring at 250rpm, stir for 3min, then stir slowly at 60rpm for 8min to promote flocculation, let stand for 45min, and the filtered wastewater enters the oxidation tank.

[0079] S3. Add the rare earth-based high-entropy composite Janus structure nanoparticle catalyst prepared in Example 2 (at a rate of 9 g / L wastewater) to the oxidation tank, set the ozone generator flow rate to 0.5 L / min, and use ozone to catalytically oxidize and degrade pollutants. The filtered wastewater then enters the evaporation tank.

[0080] S4. Wastewater undergoes first-effect evaporation at 130℃ and 0.2MPa, followed by second-effect evaporation at 110℃ and 0.09MPa, and finally third-effect evaporation at 90℃ and 0.04MPa. The condensate enters a fixed-bed activated carbon adsorption column at a flow rate of 6 m / h, remains for 20 min, and then enters the ultraviolet reactor at a flow rate of 2 m / s. The ultraviolet lamp irradiation is set to 25 mJ / cm². 2 Sterilization and filtration produce water that meets discharge standards.

[0081] Example 6

[0082] like Figure 1 As shown, a coal chemical high-salt wastewater treatment process includes:

[0083] S1. Start the wastewater booster pump and control the influent flow rate to maintain at 100 m³ / h. 3 / h, pressure 0.4 MPa, the wastewater is uniformly filtered into a vibrating screen with a pore size of 200 mesh, a frequency of 3000 times / min, and an amplitude of 3 mm, and the filtered wastewater enters the sedimentation tank.

[0084] S2, adjust the pH of the wastewater to 7.5, add a 15wt.% polyaluminum chloride aqueous solution (addition amount: 200 mg / L wastewater) under stirring at a speed of 300 rpm, stir for 2 min, slowly stir at a speed of 80 rpm for 5 min to promote flocculation, and let stand for 30 min. The filtered wastewater enters the oxidation tank.

[0085] S3, add the rare earth-based high-entropy composite Janus structure nanoparticle catalyst prepared in Example 3 (amount: 10 g / L wastewater) to the oxidation tank, set the ozone generator flow rate to 0.5 L / min, and perform catalytic ozonation degradation of the pollutants. The filtered wastewater enters the evaporation tank.

[0086] S4, evaporate the wastewater at 130℃ and 0.2 MPa for one effect, then evaporate at 110℃ and 0.09 MPa for two effects, and finally evaporate at 95℃ and 0.05 MPa for three effects. The condensed water enters a fixed bed activated carbon adsorption column at a flow rate of 8 m / h, stays for 20 min, and then enters a UV reactor at a flow rate of 2 m / s. The UV lamp irradiance is set to 30 mJ / cm 2 , sterilization, filtration, and obtain the discharge standard water.

[0087] Comparative Example 3

[0088] A coal chemical industry high-salinity wastewater treatment process, which differs from Example 6 in that the rare earth-based high-entropy composite Janus structure nanoparticle catalyst prepared in Comparative Example 1 is used in S3.

[0089] Comparative Example 4

[0090] A coal chemical industry high-salinity wastewater treatment process, which differs from Example 6 in that the rare earth-based high-entropy composite Janus structure nanoparticle catalyst prepared in Comparative Example 2 is used in S3.

[0091] Take the discharge standard water samples obtained in Examples 4-6 and Comparative Examples 3 and 4, analyze the COD using a water quality analyzer, and measure the color using a spectrophotometer.

[0092] Figure 3 The COD removal rate of the samples in Examples 4-6 and Comparative Examples 3 and 4 is shown in the table below. The COD removal rate of the samples in Examples 4-6 is all above 90%, while the COD removal rate of the samples in Comparative Examples 3 and 4 is only 20%-40%. Figure 4The color removal rates of the samples of Examples 4-6 and Comparative Examples 3 and 4 were measured. The color removal rates of the samples of Examples 4-6 were all above 90%, while the COD removal rates of the samples of Comparative Examples 3 and 4 were only 40%-60%.

[0093] This is because, in Comparative Example 3, no Ce(NO3)3·6H2O and Eu(NO3)3·6H2O were added in S1, the prepared catalyst was insufficient in active oxygen species supply, the amount of ·OH generated was sharply reduced, the catalyst was poisoned, and the catalytic activity was reduced. In Comparative Example 4, the graphitization treatment was not performed in S3, the prepared catalyst did not form a Janus structure, it was difficult to deal with complex hydrophilic / hydrophobic pollutants in wastewater, the mass transfer efficiency was reduced, the catalyst was more easily poisoned and deactivated, and the stability was reduced, and thus the removal rates of COD and color in the treated wastewater were significantly lower than those of Examples 4-6.

[0094] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A process for treating high-salt wastewater from coal chemical industry, characterized in that, include: S1. Turn on the wastewater lift pump and control the inlet flow rate so that the wastewater enters the vibrating screen evenly. After filtration, the wastewater enters the sedimentation tank. S2. Adjust the pH of the wastewater to 6.5~7.5, add coagulant while stirring, stir to promote flocculation, let stand, and filter the wastewater into the oxidation tank. S3. Rare earth-based high-entropy composite Janus structure nanoparticle catalyst is added to the oxidation tank to synergistically catalyze the oxidation and degradation of pollutants with ozone, and the filtered wastewater enters the evaporation tank. S4. Wastewater undergoes multi-effect evaporation and desalination. The condensate is adsorbed by activated carbon and then enters an ultraviolet reactor for ultraviolet sterilization and filtration to obtain water that meets discharge standards. The preparation method of the rare earth-based high-entropy composite Janus structure nanoparticle catalyst includes: A1. Add cerium salt, europium salt, tungsten salt, manganese salt, other metal salts and PAN to DMF, stir to obtain a high-entropy precursor solution, wherein the other metal salts are iron salts or cobalt salts; A2. A high-entropy precursor solution is electrospun and dried to obtain a nanofiber membrane; A3. The nanofiber membrane was placed in a chemical vapor deposition furnace for graphitization: under an air atmosphere, it was heated, then switched to an argon atmosphere, kept warm, cooled and crystallized, and W2C was preferentially nucleated to obtain a rare earth-based high-entropy composite Janus structure nanoparticle catalyst. In A1, the cerium salt is Ce(NO3)3·6H2O; the europium salt is Eu(NO3)3·6H2O; and the tungsten salt is (NH4)6H2W. 12 O 40 Manganese salt is Mn(OAc)2·4H2O; iron salt is Fe(NO3)3·9H2O; cobalt salt is Co(NO3)2·6H2O.

2. The coal chemical high-salt wastewater treatment process according to claim 1, characterized in that, In A1, the mass-to-volume ratio of cerium salt, europium salt, tungsten salt, manganese salt, Fe(NO3)3·9H2O, PAN, and DMF is (80~180) mg: (60~120) mg: (40~70) mg: (20~60) mg: (60~120) mg: (1.2~1.9) g: 15 mL; the mass-to-volume ratio of cerium salt, europium salt, tungsten salt, manganese salt, Co(NO3)2·6H2O, PAN, and DMF is (80~180) mg: (60~120) mg: (40~70) mg: (20~60) mg: (60~90) mg: (1.2~1.9) g: 15 mL; the stirring time is 10~12 h.

3. The coal chemical high-salt wastewater treatment process according to claim 1, characterized in that, In A2, the electrospinning process parameters are: anode voltage of 15~16kV, cathode voltage of 1~2kV, and needle tip-tin foil collector distance of 15~20cm; the drying temperature is 50~60℃, and the drying time is 10~12h.

4. The coal chemical high-salinity wastewater treatment process according to claim 1, characterized in that, In A3, the heating temperature is 200~230℃, and the heating time is 3~4h; the holding temperature is 800~1000℃, and the holding time is 3~5h, with a heating rate of 2℃ / min; the cooling crystallization temperature is 600~700℃, and the cooling rate is 2℃ / min.

5. The coal chemical high-salt wastewater treatment process according to claim 1, characterized in that, In step S1, the influent flow rate is 80~100 m³ / h. 3 / h, pressure controlled at 0.2~0.4MPa, the aperture of the vibrating screen is 100~200 mesh, the frequency is controlled at 1500~3000 times / min, and the amplitude is 3~5mm; in step S2, the coagulant is a 10~15wt.% polyaluminum chloride aqueous solution, the amount of coagulant added is 100~200mg / L wastewater, the stirring speed is 200~300rpm, the stirring time is 2~5min, the stirring speed to promote flocculation is 50~80rpm, the time is 5~10min, and the settling time is 30~60min.

6. The coal chemical high-salt wastewater treatment process according to claim 1, characterized in that, In step S3, the amount of catalyst used is (8~10) g / L wastewater; in step S4, the process and parameters of the multi-effect evaporation desalination include: the heating steam temperature of the first-effect evaporation is 120~130℃, and the operating pressure is 0.15~0.2MPa; the heating steam temperature of the second-effect evaporation is 100~110℃, and the operating pressure is 0.08~0.1MPa; the heating steam temperature of the third-effect evaporation is 85~95℃, and the operating pressure is 0.03~0.05MPa.

7. The coal chemical high-salt wastewater treatment process according to claim 1, characterized in that, In step S4, the activated carbon adsorption process and parameters include: using a fixed-bed activated carbon adsorption column, and using granular coconut shell activated carbon with a specific surface area ≥1000 m². 2 / g, pore size 2~5nm, wastewater enters the activated carbon adsorption column at a flow rate of 5~8m / h, and residence time is 15~20min.

8. The coal chemical high-salt wastewater treatment process according to claim 1, characterized in that, In step S4, the parameters of the ultraviolet reactor are as follows: the wavelength of the ultraviolet lamp used is 254 nm, and the irradiance is 20~30 mJ / cm². 2 The flow rate of wastewater in the ultraviolet reactor is 1~2m / s.

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