Preparation method and application of catalyst for treating MDA waste brine organic matters

Abstract

The invention discloses a preparation method of a catalyst for treating MDA waste brine organic matters, which comprises the following steps: (1) mixing a carbon source with an aluminum salt and a cerium salt, carrying out hydrothermal reaction, filtering, calcining at high temperature, and molding to obtain a CeAlOx1 / C complex; (2) mixing the CeAlOx1 / C with a zinc salt and a titanium salt, stirring and dipping, filtering, and calcining at a high temperature to obtain a carrier ZnTiOx2-CeAlOx1 / C; and (3) impregnating one or more salts of Mn, Co, Ni and Au onto the ZnTiOx2-CeAlOx1 / C carrier by adopting an excessive impregnation method, filtering, drying and calcining to obtain the catalyst. The catalyst disclosed by the invention has relatively strong adsorption capacity on MDA saline water organic matters, has dual effects of photocatalysis and ozone catalysis, and can well adsorb the organic matters and efficiently degrade aniline, phenol and other organic matters, so that the effect of treating waste saline water is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater resource utilization, and in particular to a synthesis method and application of a catalyst for treating organic matter in MDA waste brine. Technical Background

[0002] Diphenylmethane diisocyanate and polyphenylmethane polyisocyanate (collectively referred to as MDI) are one of the main raw materials in the polyurethane industry. The preparation method is to first prepare polymethylene polyphenyl polyamine (DAM) by reacting aniline and formaldehyde under acid catalysis, and then react DAM with phosgene to prepare crude MDI. The current preparation process of DAM requires the use of alkaline solution for neutralization. The neutralization process produces a large amount of waste brine, which contains amines, trace acids and other organic substances, which need to be reprocessed for environmentally friendly discharge or subsequent applications.

[0003] At present, the MDI production process usually adopts extraction, stripping and other pre-treatment methods to reduce the organic matter in the waste brine. In addition, many patents disclose methods for deep reprocessing of waste brine. Chinese patent CN 101143753A discloses an oxidation reaction and adsorption treatment of aniline and diphenylmethane diamine waste brine produced in the MDI production process to remove TOC <10ppm and TN <3ppm in the brine. Chinese patent document CN 102139976 B discloses a method for treating saline wastewater in the MDI production process, which is acidified by adding strong acid and then adsorbed and neutralized; however, it has the disadvantages of low treatment efficiency and large amount of adsorbent in the process of pH adjustment and activated carbon adsorption, and the high TOC of the effluent will affect the service life of the subsequent chlor-alkali ion membrane, and the ion membrane water inlet index needs to be strictly controlled. The deep treatment process of MDI brine reported in the literature and disclosed in the patent is long, costly, and the implementation effect is poor.

[0004] In the field of MDI brine treatment, there are few cases of deep treatment using photocatalysis-ozone oxidation. Photocatalysis technology can completely mineralize organic pollutants into carbon dioxide, water and inorganic ions without selectivity, but there are problems such as high probability of hole-electron recombination and low photocatalytic efficiency; ozone oxidation technology can efficiently oxidize organic matter, but it has a certain selectivity and cannot completely mineralize organic matter.

[0005] If the two technologies of photocatalytic oxidation and ozone oxidation can be used together, ozone can be used as an electron capture agent to reduce the recombination rate of holes and electrons and improve the efficiency of photocatalysis; photocatalysis can also enhance the oxidative degradation reaction of ozone on organic matter and improve the utilization efficiency of ozone molecules. It is a very promising water treatment technology. Summary of the invention

[0006] The present invention aims at the shortcomings of the prior art and provides a catalyst synthesis method and application for treating organic matter in MDA waste brine. The catalyst is used as a photocatalytic ozone oxidation catalyst to decompose aniline, phenol and the like in MDA waste brine into carbon dioxide, water and inorganic ions under light and ozone conditions, thereby reducing brine TOC and TN. The method is simple and has high removal efficiency.

[0007] In order to achieve the above-mentioned purpose and technical effect, the technical solution of the present invention is as follows:

[0008] A method for preparing a catalyst for treating organic matter in MDA waste brine comprises the following steps:

[0009] (1) Mix the carbon source, aluminum salt, cerium salt and water, add alkali solution to adjust to alkalinity, undergo hydrothermal reaction, filter, wash, dry, and calcine at high temperature to obtain CeAlOx 1 / C complex;

[0010] (2) The CeAlOx 1 The / C complex is mixed with one or more of zinc salt and titanium salt and water, and alkali solution is added to adjust to alkalinity. After stirring and impregnation, it is filtered, washed, dried and calcined at high temperature to obtain the carrier ZnTiOx 2 -CeAlOx 1 / C;

[0011] (3) Using an excessive impregnation method, one or more salts of Mn, Co, Ni, and Au are impregnated into the ZnTiOx 2 -CeAlOx 1 / C carrier, and the catalyst is obtained after filtering, drying and calcining.

[0012] In the present invention, the carbon source in step (1) is at least one of glucose, fructose and sucrose;

[0013] In the present invention, the aluminum salt and cerium salt in step (1) are one or more of chloride, nitrate, nitrite, sulfate and the like.

[0014] In the present invention, the mass ratio of the aluminum salt, cerium salt and carbon source in step (1) is 1:0.1-10:0.1-20, preferably 1:0.5-5:0.5-10;

[0015] In the present invention, in step (1), the amount of water added is preferably 1-100 times, more preferably 2-10 times, of the carbon source; the alkali solution is a mixed solution of one or more of potassium hydroxide, sodium hydroxide, sodium carbonate, and potassium carbonate, and its concentration is 0.01-5 mol / L;

[0016] In the present invention, the alkalinity in step (1) has a pH range of 7.2-14, preferably 8-10;

[0017] In the present invention, the hydrothermal reaction in step (1) is carried out at 120-250° C., preferably 180-220° C., for 2-48 hours, preferably 5-18 hours;

[0018] In the present invention, after the hydrothermal treatment in step (1) is completed, the mixture is cooled to room temperature, and then the precipitate is separated by filtration;

[0019] In the present invention, step (1) is washed with acetone, preferably 3-5 times;

[0020] In the present invention, step (1) is followed by drying at 50°C-150°C after washing;

[0021] In the present invention, the calcination atmosphere in step (1) is at least one of nitrogen, argon and helium;

[0022] In the present invention, the calcination temperature in step (1) is 300-1000° C., preferably 400-800° C., and the calcination time is 1-10 h, preferably 3-8 h.

[0023] In the present invention, the zinc salt and titanium salt in step (2) are one or more of chloride, nitrate, nitrite and sulfate.

[0024] In the present invention, the zinc salt and titanium salt in step (2) and the CeAlOx prepared in step (1) 1 / C mass ratio is 1:0.1-10:0.1-20, preferably 1:0.5-5:0.5-10;

[0025] In the present invention, in step (2), water is added for mixing, and the amount of water added is preferably CeAlOx 1 / C is 1-100 times, more preferably 2-10 times; the alkali solution is a mixed solution of one or more of potassium hydroxide, sodium hydroxide, sodium carbonate, and potassium carbonate, and its concentration is 0.01-5mol / L;

[0026] In the present invention, the alkalinity in step (2) has a pH range of 7.2-14, preferably 8-10;

[0027] In the present invention, the stirring and immersion in step (2) is carried out at 20-100° C., preferably 30-60° C., for 0.5-12 h, preferably 1-5 h;

[0028] In the present invention, after the immersion in step (2) is completed, the mixture is cooled to room temperature, and then the precipitate is separated by filtration;

[0029] In the present invention, step (2) is washed with acetone, preferably 3-5 times;

[0030] In the present invention, after washing in step (2), the mixture is dried at 50°C to 150°C;

[0031] In the present invention, the calcination atmosphere in step (2) is at least one of nitrogen, argon and helium;

[0032] In the present invention, the calcination temperature in step (2) is 300-1000° C., preferably 400-800° C., and the calcination time is 1-10 h, preferably 3-8 h.

[0033] In the present invention, in step (3), the mass of the impregnated metal element accounts for 0.1-10% of the carrier;

[0034] In the present invention, the one or more salts of Mn, Co, Ni and Au in step (3) are one or more of chloride, nitrate, nitrite and sulfate, and are configured into an aqueous solution with a concentration of 0.01-5 mol / L.

[0035] In the present invention, the drying in step (3) is carried out at 50-180° C., preferably 120-150° C., for 2-48 hours, preferably 5-18 hours;

[0036] In the present invention, the calcination atmosphere in step (3) is at least one of nitrogen, argon and helium;

[0037] In the present invention, the calcination temperature in step (3) is 300-1000° C., preferably 400-800° C., and the calcination time is 1-10 h, preferably 3-8 h.

[0038] The present invention also relates to a photocatalytic-ozonation catalyst for treating MDA waste brine prepared by the above method.

[0039] The present invention also relates to the use of the above-mentioned catalyst in any of the following:

[0040] (1) preparing photocatalytic-ozonation catalytic oxidation products;

[0041] (2) reducing the TOC value of MDA waste brine; wherein the MDA waste brine has a TOC of 50-80 ppm, a TN of 2-5 ppm, a formic acid of 50-80 ppm, a phenol of 10-30 ppm, and an aniline of 3-10 ppm;

[0042] For example, TOC 60ppm, TN 3ppm, formic acid 60ppm, phenol 20ppm, aniline 5ppm.

[0043] Beneficial effects of the present invention:

[0044] The catalyst prepared by the present invention has excellent catalytic performance and stability, and can decompose organic substances such as aniline, diamine, phenol, etc. in waste brine into carbon dioxide, water and inorganic ions under light and ozone catalytic conditions, thereby reducing brine TOC and TN, and the method is simple and the removal efficiency is high. DETAILED DESCRIPTION

[0045] In order to facilitate the understanding of the present invention, the present invention lists the following embodiments, but the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] In the present invention, after the excessive impregnation method in step (3), the prepared catalyst is subjected to microwave digestion method-ICP method to determine the metal content loaded thereon; the testing instrument is Agilent ICP-5900.

[0047] In the present invention, the photo-ozone catalytic oxidation experiment was carried out in a DGY-1A photochemical reactor. A 3S-T ozone generator was used to produce O 3 , the connected 3S-J2 ozone concentration detector is used to detect O 3 The output port of the ozone generator is connected to the input port of the ozone concentration tester, and the output port of the ozone concentration tester is connected to the inlet of the photochemical reactor by a polytetrafluoroethylene tube, and the O is controlled by a flow regulating valve inside the photochemical reactor. 3 The flow rate through O 3 The concentration adjustment knob controls the O 3 concentration.

[0048] In the present invention, the brine used in the experiment is taken from the MDA brine to be treated in the MDI production unit of Wanhua Chemical.

[0049] In the present invention, the TOC and TN indexes of the brine are measured by a TOC instrument, and the measuring instrument is: Jena 3100, Germany; the specific method is: take 1g of brine, dilute it to 10g with deionized water, directly sample and analyze it with the TOC instrument, and calculate the TOC and TN contents of the brine.

[0050] In the present invention, the main components of the brine, formic acid, phenol, aniline and MDA, are analyzed by liquid chromatography, and the measuring instrument is: Agilent 1260 liquid chromatograph;

[0051] Specific method: Take brine and adjust the pH to 2 with 0.1 mol / L hydrochloric acid, directly analyze by liquid phase, and quantify by external standard.

[0052] Example 1

[0053] S1: Weigh 5.0g aluminum chloride, 0.5g cerium nitrate, and 20.0g glucose into a 100ml beaker, add 100g water, and stir at room temperature to dissolve; add 0.01mol / L sodium hydroxide aqueous solution to pH=7.2, transfer to a polytetrafluoroethylene-lined hydrothermal kettle, and place in a 120℃ oven for hydrothermal heating for 48h. Take out the hydrothermal kettle, cool naturally to room temperature, filter and separate the precipitate, wash it with acetone 3 times, and then place it in a 50℃ oven to dry overnight. Put the dried solid into a crucible and roast it at 500℃ for 3h in a tubular furnace under nitrogen atmosphere to obtain the composite CeAlO x1 / C-1;

[0054] S2: weigh 5.0g zinc chloride, 0.5g titanium nitrate, 10.0g CeAlO x1 / C-1 was placed in a 100 ml beaker, 50 g of water was added, and the mixture was stirred at room temperature to dissolve; 0.01 mol / L sodium hydroxide aqueous solution was added dropwise to pH = 7.2, and the mixture was stirred at 20°C for 12 h. The mixture was naturally cooled to room temperature, and the precipitate was separated by filtration, and washed with acetone for 3 times. The precipitate was then dried in an oven at 50°C overnight. The dried solid was placed in a crucible, and calcined at 500°C for 3 h in a tubular furnace under a nitrogen atmosphere to obtain the carrier Carrier-1.

[0055] S3: Weigh 10.0g Carrier-1 into a 100ml beaker, add 20ml 0.05mol / l nickel nitrate aqueous solution, stir at room temperature to disperse it, filter and dry the solid in an oven at 120℃ for 48h, take it out and cool it to room temperature, put the dried solid into a crucible, and calcine it at 600℃ for 2h in a tubular furnace under nitrogen atmosphere to obtain catalyst C1.

[0056] Example 2

[0057] S1: Weigh 3.0g aluminum sulfate, 30.0g cerium nitrite, and 0.5g fructose into a 100ml beaker, add 50g water, and stir at room temperature to dissolve; add 5mol / L sodium hydroxide aqueous solution until pH=13, transfer to a polytetrafluoroethylene-lined hydrothermal kettle, and place in a 250℃ oven for hydrothermal heating for 2h. Take out the hydrothermal kettle, cool naturally to room temperature, filter and separate the precipitate, wash it with acetone 5 times, and then place it in a 150℃ oven to dry overnight. Put the dried solid into a crucible and calcine it at 1000℃ for 1h in a tubular furnace under argon atmosphere to obtain the composite CeAlO x1 / C-2

[0058] S2: weigh 2.0g zinc sulfate, 2.0g titanium sulfate, 20.0g CeAlO x1 / C-2 was placed in a 100 ml beaker, 60 g of water was added, and the mixture was stirred at room temperature to dissolve; 0.05 mol / L sodium hydroxide aqueous solution was added dropwise to pH = 12.5, and the mixture was stirred at 50 ° C for 10 h, and naturally cooled to room temperature. The precipitate was separated by filtration and washed with acetone for 5 times, and then dried in an oven at 150 ° C overnight. The dried solid was placed in a crucible, and calcined at 800 ° C for 3 h in a tubular furnace under a nitrogen atmosphere to obtain the carrier Carrier-2.

[0059] S3: Weigh 15.0g of Carrier-2 into a 100ml beaker, add 30ml of 0.5mol / l cobalt nitrate and 10ml of 0.1mol / l gold chloride aqueous solution, stir to disperse at room temperature, filter and dry the solid in an oven at 140°C for 4h, take out and cool to room temperature, put the dried solid into a crucible, and calcine it at 800°C for 3h in a tubular furnace under nitrogen atmosphere to obtain catalyst C2.

[0060] Example 3

[0061] S1: Weigh 6.0g aluminum sulfate, 10.0g cerium nitrite, and 30.0g sucrose into a 100ml beaker, add 80g water, and stir at room temperature to dissolve; add 0.5mol / L sodium hydroxide aqueous solution until pH=10, transfer to a polytetrafluoroethylene-lined hydrothermal kettle, and place in a 150℃ oven for hydrothermal heating for 24h. Take out the hydrothermal kettle, cool naturally to room temperature, filter and separate the precipitate, wash it with acetone 5 times, and then place it in a 120℃ oven to dry overnight. Put the dried solid into a crucible and roast it at 800℃ for 6h in a tubular furnace under nitrogen atmosphere to obtain the composite CeAlO x1 / C-3

[0062] S2: Weigh 5.0g zinc nitrate, 10.0g titanium sulfate, 10.0g CeAlO x1 / C-3 is placed in a 100ml beaker, 80g of water is added, and it is stirred at room temperature to dissolve; 0.3mol / L sodium hydroxide aqueous solution is added dropwise to pH = 12, stirred at 60°C for 8h, naturally cooled to room temperature, filtered to separate the precipitate, and washed with acetone 5 times, then placed in a 100°C oven to dry overnight, the dried solid is placed in a crucible, and calcined at 400°C for 6h in a tubular furnace under helium atmosphere to obtain carrier Carrier-3.

[0063] S3: Weigh 15.0g Carrier-3 into a 100ml beaker, add 10ml 0.5mol / l manganese nitrite and 10ml 0.1mol / l nickel chloride aqueous solution, stir to disperse at room temperature, filter and dry the solid in an oven at 140°C for 14h, take it out and cool to room temperature, put the dried solid into a crucible, and calcine it at 800°C for 1h in a tubular furnace under helium atmosphere to obtain catalyst C3.

[0064] Example 4

[0065] S1: Weigh 2.0g aluminum nitrate, 2.0g cerium chloride, and 20.0g glucose into a 100ml beaker, add 100g water, and stir at room temperature to dissolve; add 1mol / L sodium hydroxide aqueous solution until pH=12, transfer to a polytetrafluoroethylene-lined hydrothermal kettle, and place in a 180℃ oven for hydrothermal heating for 24h. Take out the hydrothermal kettle, cool naturally to room temperature, filter and separate the precipitate, wash it with acetone 4 times, and then place it in a 130℃ oven to dry overnight. Put the dried solid into a crucible and roast it at 400℃ for 8h in a tubular furnace under helium atmosphere to obtain the composite CeAlO x1 / C-4

[0066] S2: Weigh 1.0g zinc nitrate, 10.0g titanium nitrite, 15.0g CeAlO x1 / C-4 was placed in a 100 ml beaker, 120 g of water was added, and the mixture was stirred at room temperature to dissolve; 0.9 mol / L sodium hydroxide aqueous solution was added dropwise to pH = 11, and the mixture was stirred at 80°C for 0.5 h, and naturally cooled to room temperature. The precipitate was separated by filtration, and washed with acetone for 3 times, and then dried in an oven at 120°C overnight. The dried solid was placed in a crucible, and calcined at 700°C for 7 h in a tubular furnace under argon atmosphere to obtain the carrier Carrier-4.

[0067] S3: Weigh 10.0g of Carrier-4 into a 100ml beaker, add 2ml of 1.0mol / l manganese nitrite, 2ml of 1.0mol / l nickel chloride aqueous solution, 8ml of 0.1mol / l cobalt sulfate, and 15ml of 0.01mol / l gold nitrate aqueous solution, stir to disperse at room temperature, filter and dry the solid in an oven at 100°C for 24h, take it out and cool it to room temperature, put the dried solid into a crucible, and calcine it at 600°C for 10h in a tubular furnace under argon atmosphere to obtain catalyst C4.

[0068] Experimental Example Using the catalyst of the photocatalytic ozone oxidation of the present invention to treat waste brine:

[0069] The specific process of treating waste brine using the catalyst prepared in Examples 1 to 4 of the present invention in this test example is as follows:

[0070] Step 1, preparing the MDA brine to be treated from the MDI production device (the composition is shown in Table 1);

[0071] Step 2, accurately measure 100mL of MDA brine into a reaction tube, add 0.5g of the catalyst of the present invention into the reaction tube, and then move them into a photochemical reactor in sequence, move the quartz tube into the photochemical reactor and stir in the dark for 30min to reach adsorption-desorption equilibrium, turn on the ozone generator and the photochemical reactor at the same time to carry out a photo-ozone catalytic oxidation experiment, irradiate with a 250W mercury lamp, and add ozone at a concentration of 40mg / LMDA brine. Samples are taken at regular intervals, and the taken samples are centrifuged to remove the catalyst. The centrifuge speed is set to 4500r / min, centrifuged for 5min, and the supernatant is taken to measure relevant indicators.

[0072] Comparative Example:

[0073] Step 1, preparing the MDA brine to be treated from the MDI production device (the composition is shown in Table 1);

[0074] Step 2, accurately measure 1000mL of MDA brine into the resin adsorption water inlet tank, adjust the pH of the brine to 3 with hydrochloric acid, add 50g of alkali-alcohol activated Lanxiao LX-1G resin into the resin adsorption column, then pass the brine in the water inlet tank through the resin adsorption column at an adsorption rate of 2bv / h, and take the outlet clear liquid for relevant index analysis. The specific treatment results of the catalysts prepared by Examples 1 to 4 of the present invention and the comparative examples are shown in Table 1:

[0075] Table 1

[0076] TOC / ppm TN / ppm Formic acid / ppm Phenol / ppm Aniline / ppm Water Intake 60 3 60 20 5 Example 1 2 <0.1 0.5 <0.1 <0.1 Example 2 3 0.1 0.2 <0.1 <0.1 Example 3 1 <0.1 0.1 <0.1 <0.1 Example 4 3 0.1 0.6 <0.1 <0.1 Resin adsorption 10 1.5 2.6 4.8 2

[0077] The effect of treating waste brine with the photocatalytic ozone oxidation catalyst of the present invention is far better than treating waste brine by resin adsorption method, and the TOC and TN values ​​of the treated waste brine are significantly reduced.

[0078] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for treating organic matter in MDA waste brine, characterized in that: The following steps are involved: (1) mixing a carbon source, an aluminum salt, a cerium salt and water, adding alkali solution to make it alkaline, undergoing a hydrothermal reaction, filtering, washing, drying, and high-temperature calcining to obtain a CeAlOx1 / C composite; (2) mixing the CeAlOx1 / C complex with zinc salt, titanium salt and water, adding alkali solution until alkaline, stirring and impregnating, filtering, washing, drying and then calcining at high temperature to obtain a carrier ZnTiOx2-CeAlOx1 / C; (3) Using an excess impregnation method, one or more salts of Mn, Co, Ni, and Au are impregnated onto the ZnTiOx2-CeAlOx1 / C carrier, and the catalyst is obtained after filtering, drying, and calcining.

2. The preparation method according to claim 1, characterized in that: The carbon source in step (1) is at least one of glucose, fructose and sucrose; and / or The aluminum salt and cerium salt are one or more of chloride, nitrate, nitrite and sulfate; Preferably, the mass ratio of aluminum salt, cerium salt and carbon source is 1:0.1-10:0.1-20, preferably 1:0.5-5:0.5-10.

3. The preparation method according to claim 1, characterized in that: The alkali solution in step (1) or step (2) is one or more of potassium hydroxide, sodium hydroxide, sodium carbonate, and potassium carbonate, and the concentration is 0.01-5 mol / L; and / or The alkalinity has a pH range of 7.2-14, preferably 8-10.

4. The preparation method according to claim 1, characterized in that: The hydrothermal reaction in step (1) is carried out at 120-250° C., preferably 180-220° C., for 2-48 hours, preferably 5-18 hours; and / or Wash with acetone for 3-5 times; dry at 50°C-150°C after washing; and / or The calcination atmosphere is one of nitrogen, argon and helium; The calcination temperature is 300-1000°C, preferably 400-800°C, and the calcination time is 1-10h.

5. The preparation method according to claim 1, characterized in that: The zinc salt and titanium salt in step (2) are one or more of chloride, nitrate, nitrite and sulfate; Preferably, the mass ratio of zinc salt, titanium salt and CeAlOx1 / C complex is 1:0.1-10:0.1-20, preferably 1:0.5-5:0.5-10.

6. The preparation method according to claim 1, characterized in that: The stirring and impregnation in step (2) is carried out at 20-100° C., preferably 30-60° C., for 0.5-12 h; and / or Step (2) washing with acetone for 3-5 times; drying at 50°C-150°C after washing; The calcination atmosphere is one of nitrogen, argon and helium; The calcination temperature is 300-1000°C, preferably 400-800°C, and the calcination time is 1-10h.

7. The preparation method according to claim 1, characterized in that: In step (3), the one or more salts of Mn, Co, Ni and Au are one or more of chloride, nitrate, nitrite and sulfate; Preferably, the mass proportion of the impregnated metal is 0.1-10% of the carrier.

8. The preparation method according to claim 1, characterized in that: The drying in step (3) is carried out at 50-180° C., preferably 120-150° C., for 2-48 hours, preferably 5-18 hours; and / or Step (3) The calcination atmosphere is one of nitrogen, argon and helium; and / or The calcination temperature of step (3) is 300-1000° C., preferably 400-800° C., and the calcination time is 1-10 h.

9. A catalyst prepared by the method according to any one of claims 1 to 8.

10. Use of the catalyst according to claim 9 in any of the following: (1) preparing photocatalytic-ozonation catalytic oxidation products; (2) Reduce the TOC value of MDA waste brine.