Method for recycling chlorination method acidic wastewater and application

Abstract

The application discloses a method for recycling chlorination method acidic wastewater and application, and belongs to the technical field of titanium dioxide, wherein a titanium / iron-based bimetallic framework is impregnated into thermally expandable catalytic microspheres by taking the thermally expandable catalytic microspheres as a carrier, high temperature of an acid leaching reaction is utilized to make the thermally expandable catalytic microspheres expand, and catalytic centers are exposed, so that the efficiency of the acid leaching reaction is improved. In the process of treating the chlorination method acidic wastewater, the thermally expandable catalytic microspheres expand when the acid leaching is carried out at high temperature, the volume of the microspheres is increased, the internal porosity is improved, the wrapped nanometer zero-valent iron active sites are exposed, efficient catalysis and chelation are facilitated, heavy metals in the acidic wastewater are removed, complex compounds are formed with calcium and magnesium in the acidic wastewater, the heavy metals are promoted to be separated from the titanium crystal lattice, and the existence of titanium ions ensures that the catalyst cannot replace titanium in the artificial rutile, and the purity of the artificial rutile is ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium dioxide, and particularly relates to a method for recycling chlorination method acidic wastewater and application thereof. BACKGROUND

[0002] The chlorination method is one of main process means for producing titanium dioxide in China, and is widely applied due to advantages such as less waste, high quality and easy industrialization. The chlorination method mainly comprises a chlorination section, an oxidation section and a post-treatment section. In the chlorination section, rich-titanium materials such as ilmenite and rutile are ground and then fed into a boiling chlorination furnace together with petroleum coke, and high-temperature reaction is carried out in a chlorine environment. After the metal element oxides are converted into corresponding chlorides, the chlorides leave the boiling chlorination furnace together with gas. Gas-solid separation is realized through a cyclone separator and the like, and unreacted solid dust and non-volatile chlorides are collected. Further treatment with hydrochloric acid in a beating tank and collection of low-boiling titanium tetrachloride are carried out. A large amount of acidic wastewater is generated in this process, including metal chloride salts such as iron, aluminum, chromium and vanadium, among which the content of ferrous chloride is the largest, reaching 60-80 g / L.

[0003] Due to the presence of the above components in the chlorination method acidic wastewater, it is difficult to recycle the chlorination method acidic wastewater. The common treatment method at present is to add lime milk for neutralization reaction, to generate a large amount of solid waste mainly composed of iron hydroxide, and to stack or landfill the solid waste. This treatment method has high cost, low economic value and serious resource waste. Therefore, a green method for treating the chlorination method acidic wastewater and recycling the chlorination method acidic wastewater is urgently needed.

[0004] Chinese Patent CN114671462A discloses a method for recycling chlorination method acidic wastewater and application thereof. The invention reacts the chlorination method acidic wastewater with reduced ilmenite, re-places the precipitated titanium dioxide in the acidic wastewater for acid leaching reaction, thereby preparing qualified chlorination method raw material artificial rutile, and has high environmental and economic benefits. The remaining filtrate realizes enrichment of metal ions and can be recycled into a beating tank. The invention reacts the chlorination method acidic wastewater with reduced ilmenite, treats the filtrate with a suitable alkali and flocculant, thereby selectively removing vanadium, chromium, titanium and other heavy metals in the acidic wastewater, purifying the chlorination method acidic wastewater, and increasing the concentration of ferrous chloride in the acidic wastewater, so as to further obtain a ferrous chloride product. However, the acid leaching reaction efficiency is low and the purity of the artificial rutile obtained is not high enough. SUMMARY

[0005] The application aims to provide a method and application for recycling chlorination method acidic wastewater, and titanium / iron-based bimetallic framework is impregnated into thermal expansion catalytic microspheres by taking the thermal expansion catalytic microspheres as a carrier, the thermal expansion catalytic microspheres are expanded by high temperature of acid immersion reaction, the catalytic center is exposed, the efficiency of acid immersion reaction is improved, and the purity of artificial rutile is improved.

[0006] The application aims to provide a method and application for recycling chlorination method acidic wastewater, and titanium / iron-based bimetallic framework is impregnated into thermal expansion catalytic microspheres by taking the thermal expansion catalytic microspheres as a carrier, the thermal expansion catalytic microspheres are expanded by high temperature of acid immersion reaction, the catalytic center is exposed, the efficiency of acid immersion reaction is improved, and the purity of artificial rutile is improved.

[0007] A method for recycling chlorination method acidic wastewater comprises the following steps.

[0008] Step one: thermal expansion catalytic microspheres are obtained by polymerizing acrylonitrile and methacrylonitrile to form a shell layer and taking isopentane and isooctane as an expansion core layer.

[0009] Step two: titanium-based metal framework powder is obtained by coordination of tetrachloride titanium and terephthalic acid, and then iron-based metal framework is in-situ grown on the upper and lower surfaces of the titanium-based metal framework powder by esterification reaction through a wet chemical method, so as to obtain titanium / iron-based bimetallic framework powder.

[0010] Step three: then, the titanium / iron-based bimetallic framework powder is impregnated into the pores of the thermal expansion catalytic microspheres by taking the thermal expansion catalytic microspheres as a carrier, and high-efficiency catalytic material is obtained by potassium borohydride reduction.

[0011] Step four: the chlorination method acidic wastewater and the reduced titanium-iron are mixed, solid-liquid separation is performed, first filter residue and first filtrate are obtained, acid immersion reaction of the first filter residue, the acidic wastewater and the high-efficiency catalytic material is performed, artificial rutile is obtained, a flocculating agent polyacrylamide is added into the first filtrate, concentration and crystallization are performed, ferrous chloride is obtained, and a method for recycling chlorination method acidic wastewater is completed.

[0012] Further, the specific preparation steps of the thermal expansion catalytic microspheres are as follows.

[0013] Sodium chloride, colloidal silicon dioxide and deionized water are added into a reaction kettle, stirring is performed at 20-30 DEG C and 500-600 r / min for 30-40 min, the pH value is adjusted to 3-4, a water phase mixture is obtained, the water phase mixture and an oil phase mixture are added into the reaction kettle according to a mass ratio of 10:1, stirring is uniformly performed, high-speed dispersion is performed at 1500 r / min for 20-30 min, stirring is performed at 80-90 r / min under the conditions of nitrogen protection, a temperature of 70-80 DEG C, a rotation speed of 80-90 r / min and a pressure of 0.4-0.7 MPa for 20-22 h, filtration is performed, the filter cake is washed with ionized water and anhydrous ethanol for 2-4 times respectively, vacuum drying is performed at 60-70 DEG C for 1-2 h, and the thermal expansion catalytic microspheres with a particle size of 20-30 mu m are obtained.

[0014] Further, the sodium chloride, colloidal silicon dioxide and deionized water are used in a ratio of 150-170g:25-30g:1-2L.

[0015] Further, the oil phase mixture is prepared according to the following specific steps:

[0016] The acrylonitrile, methacrylonitrile, isopentane, isooctane, ethylene glycol dimethacrylate, diallyl carbonate, naphthenic oil and azobisisobutyronitrile are stirred uniformly in a reaction kettle to obtain an oil phase mixture.

[0017] Further, the acrylonitrile, methacrylonitrile, isopentane, isooctane, ethylene glycol dimethacrylate, diallyl carbonate, naphthenic oil and azobisisobutyronitrile are used in a ratio of 150-160g:70-90g:20-30g:50-70g:4-5g:3-4g:10-12g:2-3g.

[0018] Further, the titanium-based metal framework powder is prepared according to the following specific steps:

[0019] The terephthalic acid and N,N-dimethylformamide are added to a reaction kettle lined with polytetrafluoroethylene, stirred at 20-25°C and 500-600r / min for 20-30min, then titanium tetrachloride is added, continue to stir for 20-30min, then add 14-15mL of 1mol / L acetic acid solution, ultrasonic dispersion for 40-60min, heat to 120-140°C, continue to stir for 24-26h, naturally cool to room temperature, filter, wash the filter cake with N,N-dimethylformamide and methanol for 2-4 times respectively, vacuum drying at 60-70°C for 1-2h to obtain the titanium-based metal framework powder.

[0020] Further, the terephthalic acid, N,N-dimethylformamide and titanium tetrachloride are used in a ratio of 80-90g:2-3L:120-140g.

[0021] Further, the titanium / iron-based bimetallic framework powder is prepared according to the following specific steps:

[0022] The titanium-based metal framework powder, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide are added to a reaction kettle lined with polytetrafluoroethylene, stirred at 20-25°C and 500-600r / min for 20-30min, then iron chloride is added, continue to stir for 20-30min, then add 1mol / L acetic acid solution, ultrasonic dispersion for 40-60min, heat to 120-140°C, continue to stir for 24-26h, naturally cool to room temperature, filter, wash the filter cake with N,N-dimethylformamide and methanol for 2-4 times respectively, vacuum drying at 60-70°C for 1-2h to obtain the titanium / iron-based bimetallic framework powder.

[0023] Further, the use amount ratio of titanium-based metal skeleton powder, 2,5-dihydroxyterephthalic acid, N,N-dimethylformamide, ferric chloride and acetic acid solution is 80-90g: 120-140g: 3-4L: 70-80g: 14-15mL.

[0024] Further, the specific preparation steps of the high-efficiency catalytic material are as follows:

[0025] The titanium / iron-based bimetallic skeleton powder, the thermal expansion catalytic microspheres and the N,N-dimethylformamide are reacted in a reaction kettle under the protection of nitrogen at 50-55 DEG C and 500-600r / min for 1-2h, then zinc sulfate and a 40-50wt% potassium borohydride solution are added into the reaction kettle at a speed of 30mL / min, after the addition is completed, the reaction is continued for 4-5h, then the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum drying is carried out at 60-70 DEG C for 1-2h, so as to obtain the high-efficiency catalytic material.

[0026] Further, the use amount ratio of titanium / iron-based bimetallic skeleton powder, thermal expansion catalytic microspheres, N,N-dimethylformamide, zinc sulfate and potassium borohydride solution is 70-80g: 150-160g: 1-2L: 3-4g: 120-140mL.

[0027] The application also provides an application of the method for recycling chlorination method acidic wastewater in the production of titanium dioxide.

[0028] The application has the following beneficial effects:

[0029] 1. The method for recycling chlorination method acidic wastewater provided by the application can obtain artificial rutile with high purity and few impurities, the thermal expansion catalytic microspheres are obtained by polymerization of propylene and methacrylonitrile to form a shell layer and by using isopentane and isooctane as an expansion core layer, the titanium-based metal skeleton powder is obtained by coordination of terephthalic acid and titanium tetrachloride, the titanium / iron-based bimetallic skeleton powder is obtained by in-situ growth of iron-based metal skeleton on the upper and lower surfaces of the titanium-based metal skeleton powder through esterification reaction by using a wet chemical method, the high-efficiency catalytic material is obtained by impregnating the titanium / iron-based bimetallic skeleton powder into the pores of the thermal expansion catalytic microspheres and reducing the titanium / iron-based bimetallic skeleton powder by potassium borohydride, and the degree and efficiency of the acid leaching reaction can be improved by adding the high-efficiency catalytic material in the acid leaching reaction.

[0030] 2. The high-efficiency catalytic material of the present application, with the thermal expansion catalytic microspheres as the carrier, the titanium / iron-based bimetallic framework powder is impregnated into the pores of the thermal expansion catalytic microspheres, after reduction by potassium borohydride, the iron metal framework in the titanium / iron-based bimetallic framework is reduced into nano zero-valent iron, and the iron metal framework collapses, which promotes the uniform loading of nano zero-valent iron on the surface, inhibits the agglomeration of nano zero-valent iron, and in the process of chlorination method acid wastewater treatment, when acid leaching at high temperature, the thermal expansion catalytic microspheres expand, the volume of the microspheres increases, the internal porosity improves, the wrapped nano zero-valent iron active sites are exposed, which is beneficial to efficient catalysis and chelation, and facilitates the removal of heavy metals in acid wastewater, forms a complex with calcium and magnesium in acid wastewater, promotes its separation from the titanium lattice, and the presence of titanium ions ensures that the catalyst will not replace the titanium in artificial rutile, ensuring the purity of artificial rutile, at room temperature, the microspheres are in a shrinking state, and the nano zero-valent iron is sealed in the closed pores, which isolates oxygen and water vapor, and avoids the easy oxidation of traditional nano zero-valent iron in air. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] Embodiment 1: A method for recycling chlorination method acid wastewater, comprising the following steps:

[0033] S1: 150g of acrylonitrile, 70g of methacrylonitrile, 20g of isopentane, 50g of isooctane, 4g of ethylene glycol dimethacrylate, 3g of diallyl carbonate, 10g of naphthenic oil and 2g of azobisisobutyronitrile are added into a reaction kettle and stirred uniformly to obtain an oil phase mixture; 150g of sodium chloride, 25g of colloidal silicon dioxide and 1L of deionized water are added into the reaction kettle, stirred at 20℃ and 500r / min for 30min, and the pH value is adjusted to 3 to obtain an aqueous phase mixture; the aqueous phase mixture and the oil phase mixture are added into the reaction kettle and stirred uniformly at a mass ratio of 10:1, high-speed dispersion is carried out at 1500r / min for 20min, stirring is carried out under the conditions of nitrogen protection, temperature of 70℃, rotation speed of 80r / min and pressure of 0.4MPa for 20h, filtration is carried out, the filter cake is washed with ionized water and anhydrous ethanol for 2 times respectively, vacuum drying is carried out at 60℃ for 1h, and thermal expansion catalytic microspheres with a particle size of 20μm are obtained.

[0034] S2: 80 g of terephthalic acid and 2 L of N,N-dimethylformamide were added to a reaction kettle lined with polytetrafluoroethylene, stirred at 20 DEG C and 500 r / min for 20 min, then 120 g of titanium tetrachloride was added, and stirring was continued for 20 min, then 14 mL of acetic acid solution with a concentration of 1 mol / L was added, ultrasonic dispersion was carried out for 40 min, heating was carried out to 120 DEG C, and stirring was continued for 24 h, and then natural cooling was carried out to room temperature, filtration was carried out, the filter cake was washed with N,N-dimethylformamide and methanol for 2 times respectively, vacuum drying was carried out at 60 DEG C for 1 h, and then titanium-based metal skeleton powder was obtained.

[0035] S3: 80 g of titanium-based metal skeleton powder, 120 g of 2,5-dihydroxyterephthalic acid and 3 L of N,N-dimethylformamide were added to a reaction kettle lined with polytetrafluoroethylene, stirred at 20 DEG C and 500 r / min for 20 min, then 70 g of iron chloride was added, and stirring was continued for 20 min, then 14 mL of acetic acid solution with a concentration of 1 mol / L was added, ultrasonic dispersion was carried out for 40 min, heating was carried out to 120 DEG C, and stirring was continued for 24 h, and then natural cooling was carried out to room temperature, filtration was carried out, the filter cake was washed with N,N-dimethylformamide and methanol for 2 times respectively, vacuum drying was carried out at 60 DEG C for 1 h, and then titanium / iron-based bimetal skeleton powder was obtained.

[0036] S4: 70 g of titanium / iron-based bimetal skeleton powder, 150 g of thermally expandable catalytic microspheres and 1 L of N,N-dimethylformamide were added to a reaction kettle, vacuum impregnation was carried out at 50 DEG C and 500 r / min for 1 h under the protection of nitrogen, then 3 g of zinc sulfate and 120 mL of potassium borohydride solution with a mass fraction of 40% were added dropwise into the reaction kettle at a speed of 30 mL / min, after the dropwise addition was completed, reaction was continued for 4 h, suction filtration was carried out, the filter cake was washed with deionized water and anhydrous ethanol for 2 times respectively, vacuum drying was carried out at 60 DEG C for 1 h, and then high-efficiency catalytic material was obtained.

[0037] S5: chlorination method acid wastewater and reduced ilmenite were mixed according to a ratio of 5:1, after sufficient reaction at 80 DEG C for 3 h, solid-liquid separation was carried out, and first filter residue and first filtrate were obtained; the first filter residue, acid wastewater and high-efficiency catalytic material were mixed according to a ratio of 4:1:0.2, acid leaching reaction was carried out at 80 DEG C for 2 h, and then solid-liquid separation was carried out, and second filter residue and second filtrate were obtained respectively; the second filtrate was refluxed into the chlorination method acid wastewater for recycling; filtration was carried out, the filter cake was washed with deionized water and anhydrous ethanol for 2 times respectively, vacuum drying was carried out at 60 DEG C for 1 h, and then synthetic rutile was obtained, the filtrate was reserved, 0.5 g of flocculating agent polyacrylamide was added into the first filtrate to adjust the pH value to 4, and a mass fraction of 4% sodium hydroxide solution was added, and then concentration crystallization was carried out, and ferrous chloride was obtained, and a method for recycling chlorination method acid wastewater was completed.

[0038] Example 2: a method for recycling chlorination method acid wastewater, comprising the following steps:

[0039] S1: 155 g of acrylonitrile, 80 g of methacrylonitrile, 25 g of isopentane, 60 g of isooctane, 4.5 g of ethylene glycol dimethacrylate, 3.5 g of diallyl carbonate, 11 g of naphthenic oil, and 2.5 g of azobisisobutyronitrile were added into a reaction kettle and stirred uniformly to obtain an oil phase mixture; 160 g of sodium chloride, 27.5 g of colloidal silicon dioxide, and 1.5 L of deionized water were added into the reaction kettle, stirred at 25°C and 550 r / min for 35 min, and the pH value was adjusted to 3.5 to obtain an aqueous phase mixture; the aqueous phase mixture and the oil phase mixture were added into the reaction kettle in a mass ratio of 10:1 and stirred uniformly, high-speed dispersed at 1500 r / min for 25 min, stirred at a temperature of 75°C, a rotation speed of 85 r / min, and a pressure of 0.55 MPa for 21 h under nitrogen protection, filtered, the filter cake was washed with ionized water and anhydrous ethanol for 3 times respectively, and vacuum dried at 65°C for 1.5 h to obtain thermally expandable catalytic microspheres with a particle size of 25 μm.

[0040] S2: 85 g of terephthalic acid and 2.5 L of N,N-dimethylformamide were added into a reaction kettle lined with polytetrafluoroethylene, stirred at 22.5°C and 550 r / min for 25 min, then 130 g of titanium tetrachloride was added and stirred for another 25 min, then 14.5 mL of acetic acid solution with a concentration of 1 mol / L was added, ultrasonic dispersed for 50 min, heated to 130°C, and stirred for another 25 h, then naturally cooled to room temperature, filtered, the filter cake was washed with N,N-dimethylformamide and methanol for 3 times respectively, and vacuum dried at 65°C for 1.5 h to obtain a titanium-based metal skeleton powder.

[0041] S3: 85 g of titanium-based metal skeleton powder, 130 g of 2,5-dihydroxyterephthalic acid, and 3.5 L of N,N-dimethylformamide were added into a reaction kettle lined with polytetrafluoroethylene, stirred at 22.5°C and 550 r / min for 25 min, then 75 g of iron chloride was added and stirred for another 25 min, then 14.5 mL of acetic acid solution with a concentration of 1 mol / L was added, ultrasonic dispersed for 50 min, heated to 130°C, and stirred for another 25 h, then naturally cooled to room temperature, filtered, the filter cake was washed with N,N-dimethylformamide and methanol for 3 times respectively, and vacuum dried at 65°C for 1.5 h to obtain a titanium / iron-based bimetallic skeleton powder.

[0042] S4: 75 g of titanium / iron-based bimetallic framework powder, 155 g of thermally expandable catalytic microspheres, and 1.5 L of N,N-dimethylformamide were added to a reaction kettle under nitrogen protection, vacuum impregnated at 52.5℃ and 550 r / min for 1.5 h, then 3.5 g of zinc sulfate and 130 mL of 45% mass fraction potassium borohydride solution were added at a speed of 30 mL / min, after the addition was completed, the reaction was continued for 4.5 h, filtration was performed, the filter cake was washed with deionized water and anhydrous ethanol for 3 times respectively, and vacuum drying was performed at 65℃ for 1.5 h to obtain a high-efficiency catalytic material.

[0043] S5: The chlorination method acid wastewater and the reduced ilmenite were mixed according to the mass ratio of 5:1, and after sufficient reaction at 85℃ for 4h, solid-liquid separation was performed to obtain first filter residue and first filtrate; the first filter residue, acid wastewater and high-efficiency catalytic material were mixed according to the mass ratio of 4:1:0.2, and acid leaching reaction was performed at 85℃ for 2.5h, and solid-liquid separation was performed to obtain second filter residue and second filtrate respectively; the second filtrate was refluxed to the chlorination method acid wastewater for recycling; filtration was performed, the filter cake was washed with deionized water and anhydrous ethanol for 3 times respectively, and vacuum drying was performed at 65℃ for 1.5h to obtain artificial rutile, the filtrate was reserved, 4.5% mass fraction sodium hydroxide solution was added to the first filtrate to adjust the pH value to 4.5, and 0.55 g of flocculating agent polyacrylamide was added, concentration crystallization was performed to obtain ferrous chloride, and a method for recycling chlorination method acid wastewater was completed.

[0044] Example 3: A method for recycling chlorination method acid wastewater, comprising the following steps:

[0045] S1: 160 g of acrylonitrile, 90 g of methacrylonitrile, 30 g of isopentane, 70 g of isooctane, 5 g of ethylene glycol dimethacrylate, 4 g of diallyl carbonate, 12 g of naphthenic oil and 3 g of azobisisobutyronitrile were added to a reaction kettle and stirred uniformly to obtain an oil phase mixture; 170 g of sodium chloride, 30 g of colloidal silicon dioxide and 2 L of deionized water were added to the reaction kettle, stirred at 30℃ and 600 r / min for 40 min, and the pH value was adjusted to 4 to obtain an aqueous phase mixture; the aqueous phase mixture and the oil phase mixture were added to the reaction kettle according to a mass ratio of 10:1 and stirred uniformly, high-speed dispersion was performed at 1500 r / min for 30 min, stirring was performed under the conditions of nitrogen protection, a temperature of 80℃, a rotation speed of 90 r / min and a pressure of 0.7 MPa for 22 h of polymerization, filtration was performed, the filter cake was washed with ionized water and anhydrous ethanol for 4 times respectively, and vacuum drying was performed at 70℃ for 2h to obtain thermally expandable catalytic microspheres with a particle size of 30 μm.

[0046] S2: 90 g of terephthalic acid and 3 L of N,N-dimethylformamide were added into a reaction kettle lined with polytetrafluoroethylene, stirred at 25 DEG C and 600 r / min for 30 min, then 140 g of titanium tetrachloride was added, and stirring was continued for 30 min, then 15 mL of acetic acid solution with a concentration of 1 mol / L was added, ultrasonic dispersion was carried out for 60 min, heating was carried out to 140 DEG C, and stirring was continued for 26 h, and then natural cooling was carried out to room temperature, filtration was carried out, the filter cake was washed with N,N-dimethylformamide and methanol respectively for 4 times, vacuum drying was carried out at 70 DEG C for 2 h, and then titanium-based metal skeleton powder was obtained.

[0047] S3: 90 g of titanium-based metal skeleton powder, 140 g of 2,5-dihydroxyterephthalic acid and 4 L of N,N-dimethylformamide were added into a reaction kettle lined with polytetrafluoroethylene, stirred at 25 DEG C and 600 r / min for 30 min, then 80 g of iron chloride was added, and stirring was continued for 30 min, then 15 mL of acetic acid solution with a concentration of 1 mol / L was added, ultrasonic dispersion was carried out for 60 min, heating was carried out to 140 DEG C, and stirring was continued for 26 h, and then natural cooling was carried out to room temperature, filtration was carried out, the filter cake was washed with N,N-dimethylformamide and methanol respectively for 4 times, vacuum drying was carried out at 70 DEG C for 2 h, and then titanium / iron-based bimetal skeleton powder was obtained.

[0048] S4: 80 g of titanium / iron-based bimetal skeleton powder, 160 g of thermally expandable catalytic microspheres and 2 L of N,N-dimethylformamide were added into a reaction kettle, vacuum impregnation was carried out at 55 DEG C and 600 r / min for 2 h under the protection of nitrogen, then 4 g of zinc sulfate and 140 mL of potassium borohydride solution with a mass fraction of 50% were added dropwise into the reaction kettle at a speed of 30 mL / min, after the dropwise addition was completed, reaction was continued for 5 h, suction filtration was carried out, the filter cake was washed with deionized water and anhydrous ethanol respectively for 4 times, vacuum drying was carried out at 70 DEG C for 2 h, and then high-efficiency catalytic material was obtained.

[0049] S5: chlorination method acid wastewater and reduced ilmenite were mixed according to a ratio of 5:1, solid-liquid separation was carried out after sufficient reaction at 90 DEG C for 5 h, and then first filter residue and first filtrate were obtained; the first filter residue, acid wastewater and high-efficiency catalytic material were mixed according to a ratio of 4:1:0.2, acid leaching reaction was carried out at 90 DEG C for 3 h, and then solid-liquid separation was carried out and second filter residue and second filtrate were obtained respectively; the second filtrate was refluxed into the chlorination method acid wastewater for recycling; filtration was carried out, the filter cake was washed with deionized water and anhydrous ethanol respectively for 4 times, vacuum drying was carried out at 70 DEG C for 2 h, and then artificial rutile was obtained, the filtrate was reserved, 0.6 g of flocculating agent polyacrylamide was added into the first filtrate to adjust the pH value to 5, and sodium hydroxide solution with a mass fraction of 5% was added, concentration crystallization was carried out, and then ferrous chloride was obtained, and a method for recycling chlorination method acid wastewater was completed.

[0050] Comparative Example 1: on the basis of Example 3, step S1 treatment was not carried out, and the thermally expandable catalytic microspheres in step S4 were removed.

[0051] Comparative Example 2: On the basis of Example 3, the titanium-based metal framework powder in step S3 is removed without being treated in step S2, and step S3 is omitted.

[0052] Comparative Example 3: On the basis of Example 3, the titanium / iron-based bimetallic framework powder in step S4 is replaced with a mixture of titanium-based metal framework powder and nano zero-valent iron powder without being treated in step S3.

[0053] Performance tests are performed on Examples 1-3 and Comparative Examples 1-3, and the purity of the artificial rutile is tested, and the results are shown in Table 1:

[0054] Table 1

[0055] Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Synthetic rutile grade (%) 90.2 92.5 94.8 80.7 85.9 82.3 Calcium oxide content (%) 0.11 0.10 0.09 0.58 0.42 0.56 Magnesium oxide content (%) 0.68 0.63 0.52 0.95 0.73 0.82

[0056] As can be seen from Table 1, the purity of the artificial rutile obtained in Examples 1-3 is significantly higher than that of the comparative examples, and the impurities are less, which shows that the method for recycling chlorination method acid wastewater provided by the present application has high purity of artificial rutile and is suitable for the production of titanium dioxide.

[0057] In Comparative Example 1, the thermal expansion catalyst microspheres in step S4 are removed, and the thermal expansion catalyst microspheres act as a carrier for the catalyst. When acid leaching at high temperature, the thermal expansion catalyst microspheres expand, increasing the volume of the microspheres and the internal porosity, exposing the wrapped nano zero-valent iron active sites, which is beneficial to efficient catalysis and chelation, facilitating the removal of heavy metals in the acid wastewater, forming complexes with calcium and magnesium in the acid wastewater, promoting their separation from the titanium lattice, and the presence of titanium ions ensures that the catalyst will not replace the titanium in the artificial rutile, ensuring the purity of the artificial rutile. At room temperature, the microspheres are in a contracted state, and the nano zero-valent iron is sealed in the closed pores, isolating oxygen and water vapor, and avoiding the easy oxidation of traditional nano zero-valent iron in air.

[0058] In Comparative Example 2, the titanium-based metal framework powder in step S3 is removed, and the titanium-based metal framework as a shell layer improves the overall strength and adsorption performance of the catalyst, indirectly improving the catalytic efficiency, and the increased titanium ions can avoid replacing the titanium in the artificial rutile, ensuring the purity of the artificial rutile.

[0059] In Comparative Example 3, the titanium / iron-based bimetallic framework powder in step S4 is replaced with a mixture of titanium-based metal framework powder and nano zero-valent iron powder, and the nano effect of nano zero-valent iron makes it easy to agglomerate due to its high surface energy. The iron-based metal framework is grown in situ on the upper and lower surfaces of the nano zero-valent iron by esterification reaction through wet chemical method, obtaining titanium / iron-based bimetallic framework powder, ensuring uniform loading of subsequent nano zero-valent iron and inhibiting agglomeration of nano zero-valent iron.

[0060] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application.

Claims

1. A method for recycling chlorinated acidic waste water, characterized by, It comprises the following steps: Step one: forming a shell layer by polymerization of acrylonitrile and methacrylonitrile, isopentane and isooctane as the expanded core layer, to obtain a thermally expandable catalytic microsphere; Step two: obtaining a titanium-based metal skeleton powder by coordination of terephthalic acid and titanium tetrachloride, and then growing an iron-based metal skeleton on the upper and lower surfaces of the titanium-based metal skeleton powder by esterification reaction through a wet chemical method to obtain a titanium / iron-based bimetallic skeleton powder; Step three: then, the titanium / iron-based bimetallic skeleton powder is impregnated into the pores of the thermally expandable catalytic microsphere by taking the thermally expandable catalytic microsphere as a carrier, and is reduced by potassium borohydride to obtain a high-efficiency catalytic material; Step four: mixing chlorination method acidic wastewater and reduced ilmenite, solid-liquid separation to obtain first filter residue and first filtrate, then the first filter residue, acidic wastewater and high-efficiency catalytic material are reacted by acid leaching to obtain artificial rutile, and then a flocculating agent polyacrylamide is added to the first filtrate, concentrated and crystallized to obtain ferrous chloride, to complete a method for recycling chlorination method acidic wastewater; The specific preparation steps of the thermally expandable catalytic microsphere are as follows: Sodium chloride, colloidal silicon dioxide and deionized water are added into a reaction kettle, stirred at 20-30 DEG C and 500-600 r / min for 30-40 min, the pH value is adjusted to 3-4 to obtain an aqueous phase mixture; the aqueous phase mixture and an oil phase mixture are added into the reaction kettle according to a mass ratio of 10:1, stirred uniformly, dispersed at a high speed of 1500 r / min for 20-30 min, stirred at a temperature of 70-80 DEG C, a rotation speed of 80-90 r / min and a pressure of 0.4-0.7 MPa under the protection of nitrogen for 20-22 h, filtered, washed and vacuum dried to obtain the thermally expandable catalytic microsphere with a particle size of 20-30 mu m; The specific preparation steps of the oil phase mixture are as follows: Acrylonitrile, methacrylonitrile, isopentane, isooctane, ethylene glycol dimethacrylate, carbon dioxide allyl ester, naphthenic oil and azobisdimethyl isobutyronitrile are added into a reaction kettle and stirred uniformly to obtain the oil phase mixture.

2. The method of recycling chlorinated acidic waste water according to claim 1, wherein, The amount ratio of the sodium chloride, colloidal silicon dioxide and deionized water is 150-170 g:25-30 g:1-2 L.

3. The method of recycling chlorinated acidic waste water according to claim 1, wherein, The amount ratio of the acrylonitrile, methacrylonitrile, isopentane, isooctane, ethylene glycol dimethacrylate, carbon dioxide allyl ester, naphthenic oil and azobisdimethyl isobutyronitrile is 150-160 g:70-90 g:20-30 g:50-70 g:4-5 g:3-4 g:10-12 g:2-3 g.

4. The method of recycling chlorinated acidic waste water according to claim 1, wherein The specific preparation steps of the titanium-based metal skeleton powder are as follows: Terephthalic acid and N,N-dimethylformamide are added into a reaction kettle lined with polytetrafluoroethylene, stirred at 20-25 DEG C and 500-600 r / min for 20-30 min, then titanium tetrachloride is added, and stirring is continued for 20-30 min, then 14-15 mL of acetic acid solution with a concentration of 1 mol / L is added, ultrasonic dispersion is carried out for 40-60 min, heating is carried out to 120-140 DEG C, and stirring is continued for 24-26 h, then natural cooling, filtration, washing and vacuum drying are carried out to obtain the titanium-based metal skeleton powder; The amount ratio of the terephthalic acid, N,N-dimethylformamide and titanium tetrachloride is 80-90g:2-3L:120-140g.

5. The method of recycling chlorinated acidic waste water according to claim 1, wherein The titanium / iron-based bimetallic framework powder is prepared by the following steps: The titanium-based metal framework powder, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide are added into a reaction kettle lined with polytetrafluoroethylene, stirred at 20-25℃ and 500-600r / min for 20-30min, then iron chloride is added, and stirring is continued for 20-30min, then 1mol / L acetic acid solution is added, ultrasonic dispersion is performed for 40-60min, heating is performed to 120-140℃, and stirring is continued for 24-26h, and then natural cooling, filtration, washing and vacuum drying are performed to obtain the titanium / iron-based bimetallic framework powder.

6. The method of recycling chlorinated acidic waste water according to claim 5, wherein, The amount ratio of the titanium-based metal framework powder, 2,5-dihydroxyterephthalic acid, N,N-dimethylformamide, iron chloride and acetic acid solution is 80-90g:120-140g:3-4L:70-80g:14-15mL.

7. The method of recycling chlorinated acidic waste water according to claim 1, wherein The high-efficiency catalytic material is prepared by the following steps: The titanium / iron-based bimetallic framework powder, thermally expandable catalytic microspheres and N,N-dimethylformamide are added into a reaction kettle, vacuum impregnation is performed at 50-55℃ and 500-600r / min for 1-2h under nitrogen protection, then zinc sulfate and 40-50wt% potassium borohydride solution are added into the reaction kettle at a speed of 30mL / min, after the addition is completed, reaction is continued for 4-5h, suction filtration is performed, the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum drying is performed at 60-70℃ for 1-2h to obtain the high-efficiency catalytic material. The amount ratio of the titanium / iron-based bimetallic framework powder, thermally expandable catalytic microspheres, N,N-dimethylformamide, zinc sulfate and potassium borohydride solution is 70-80g:150-160g:1-2L:3-4g:120-140mL.

8. Use of the method for recycling chlorination method acidic wastewater in claim 1-7 in the production of titanium dioxide.