Method for treating COD (Chemical Oxygen Demand) in acetophenone-containing waste acid

Abstract

The invention discloses a method for treating COD (Chemical Oxygen Demand) in acetophenone-containing waste acid, and relates to the technical field of waste acid treatment. The method for treating the COD in the acetophenone-containing waste acid comprises the following steps: S1, pretreating the acetophenone-containing waste acid; s2, carrying out oxidation reaction on the purified acetophenone-containing waste acid, and carrying out gas-liquid separation to obtain acetophenone-containing waste acid for primary reaction; and S3, adding sodium hypochlorite into the acetophenone-containing waste acid after the primary reaction to carry out secondary oxidation, carrying out gas-liquid separation on the waste acid after the secondary oxidation, and condensing and recycling the waste acid. According to the method, COD is controlled to be efficiently oxidized into CO2 and other gases through cooperation of two times of oxidation, the COD removal rate of acetophenone-containing waste acid can reach 94% at most through absorption and recovery of alkali liquor, and the acetophenone-containing waste acid can be recycled in the product production process.

Description

Technical Field

[0001] The present invention relates to the technical field of waste acid treatment, and more specifically, to a method for treating COD in waste acid containing acetophenone. Background Art

[0002] A large amount of inorganic waste acid is generated in the production process of pesticides, pharmaceuticals and dye intermediates, and the acidity is generally between 5-30%, and sometimes even higher. The source of acetophenone-containing waste acid is the by-product of the production process of pharmaceutical intermediates. It is generated in the Hooke reaction using anhydrous aluminum chloride as a catalyst. The waste acid has the characteristics of high acidity and high COD content. The COD content in these waste acids is high, and the composition and source of COD are complex, but it is mainly caused by the introduction of organic matter as a by-product of the intermediates. The COD value in the waste acid is often higher than 2000 mg / L, and some are even as high as hundreds of thousands of mg / L. Some waste acids also contain high concentrations of pollutants such as ammonia nitrogen. This type of waste acid contains derivatives such as ketones and aldehydes, and has low biodegradability, which is very unfavorable to the environment and the recycling of waste acids. At present, many waste-producing enterprises can only use the neutralization method to precipitate and landfill or incinerate the residue to dispose of it, and this disposal method will cause a large number of subsequent environmental problems. Wet oxidation and wet catalytic oxidation are very effective technologies for treating waste acid containing medium and high concentrations of organic matter. However, when conducting oxidation reactions in conventional reactors under high acidity and high COD conditions, there is a safety risk of flash explosion. Second, the reaction is not controllable enough. Third, if the catalyst is not selected correctly, the oxidation capacity and effect cannot be guaranteed.

[0003] The prior art discloses a method for treating waste acid produced by the synthesis of m-nitroacetophenone, comprising the following steps: S1: extracting the waste acid produced by the nitration reaction of acetophenone with acetophenone for 1-3 times at room temperature, and separating the waste acid A; S2: freezing and stirring the waste acid A at a temperature of -5°C to -20°C, and filtering to obtain waste acid B; S3: distilling the waste acid B under negative pressure and a temperature of 170 to 210°C to obtain waste acid C, wherein the mass concentration of sulfuric acid in the waste acid C is more than 92%, and the COD is 400 to 1200 mg / L. Although the prior art solution can also reduce the COD in the waste acid, it needs to be subjected to operations such as extraction, low-temperature freezing at -5°C to -20°C, and high-temperature distillation at 170 to 210°C, which is not only complicated to operate, but also has harsh reaction conditions, and it is not clear that it can be used for the treatment of waste acid containing acetophenone with high acidity and high COD. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects and shortcomings of the existing methods for treating waste acid containing acetophenone, such as harsh reaction conditions, complicated steps, and inability to treat waste acid containing acetophenone with high acidity and high COD, and to provide a method for treating COD in waste acid containing acetophenone. The method adopts two-stage continuous catalytic oxidation to solve the difficulty in treating a large amount of COD pollution factors in waste acid containing acetophenone, and realizes the recycling of waste acid containing acetophenone.

[0005] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0006] A method for treating COD in waste acid containing acetophenone comprises the following steps:

[0007] S1. Pretreating the waste acid containing acetophenone to remove insoluble impurities in the waste acid to obtain purified waste acid containing acetophenone;

[0008] S2. The purified waste acid containing acetophenone is heated to above 50°C, hydrogen peroxide is added, the pressure of the system is maintained at 0.3-2MPa, the temperature is 50-100°C, and the gas-liquid separation is performed after the oxidation reaction to obtain the waste acid containing acetophenone in the primary reaction;

[0009] S3. adding the waste acid containing acetophenone after the primary reaction into a reactor mixed with a Ce-Mn-Mo-Cu homogeneous catalyst, heating to above 70°C, adding sodium hypochlorite, sodium chlorate or potassium chlorate for secondary oxidation, the pressure of the system is 0.8-3MPa, the temperature is 90-150°C, the waste acid after the secondary oxidation is separated into gas and liquid, and the waste acid is condensed and reused,

[0010] Among them, the total reaction time of S2 and S3 is 100-150s.

[0011] Among them, it should be noted that:

[0012] In S1, by pretreating the waste acid containing acetophenone, insoluble impurities in the waste acid can be removed, thereby achieving the purpose of purifying the waste acid and preventing the continuous reactor from being blocked.

[0013] In step S2, hydrogen peroxide is used to perform the primary oxidation reaction on the purified acetophenone-containing waste acid. By controlling the reaction temperature and pressure, part of the COD is oxidized to CO under this pressure system. 2 Gas, waste acid gas-liquid separation after secondary oxidation to oxidized CO 2 Gas and waste acid containing acetophenone are separated.

[0014] In step S3, sodium hypochlorite catalyzed by Ce-Mn-Mo-Cu homogeneous catalyst is used to perform secondary oxidation on the acetophenone-containing waste acid after the primary reaction. Under the condition of the inherent acidity of the acetophenone-containing waste acid and the synergistic catalytic action of the catalyst, sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances to perform secondary oxidation reaction on the waste acid itself. Most of the remaining COD will be oxidized under this pressure system. The oxidized waste acid is separated into gas and liquid, and CO 2 Wait for the gas and waste acid to be separated again.

[0015] Among them, hydrogen peroxide is used in the initial reaction to oxidize and remove the easily reactive organic molecular impurities first, and then a secondary strong oxidation is carried out.

[0016] Among them, in a specific embodiment, the reaction of the present invention is preferably carried out in a reactor made of a material that is acid-resistant, oxidation-resistant, pressure-resistant, and capable of achieving rapid heat conduction, and the entire reaction process of the present invention can be carried out continuously.

[0017] In a specific implementation, the filter in S1 uses a filter bag with a mesh size of 1000 or more and performs medium-pressure filtration at 0.5 MPa. When the pressure continues to rise, it indicates that the filter bag is clogged and needs to be replaced in time.

[0018] In a specific embodiment, in order to save energy, the waste acid filtered in S1 can be heat exchanged with the waste acid liquid after the secondary oxidation reaction through a heat exchanger to increase the temperature of the liquid.

[0019] The method for treating COD in waste acid containing acetophenone of the present invention has a reaction residence time of 100-150s in a two-stage continuous oxidation reaction of waste acid containing acetophenone, and can achieve a COD removal rate of 75-95% in waste acid containing acetophenone. The separated waste acid is condensed through a heat exchanger, and the waste acid after cooling treatment is reused in the enterprise product production process as a resource comprehensive utilization raw material.

[0020] In a specific embodiment, preferably, the reaction time in S2 is 30 to 80 seconds.

[0021] In a specific embodiment, preferably, the reaction time in S2 is 50 s, and the reaction time in S3 is 80-100 s.

[0022] In a specific embodiment, preferably, the system pressure is maintained at 0.5-1 MPa and the temperature is maintained at 60-80°C in S2. In a specific embodiment, preferably, the system pressure is maintained at 1-2.5 MPa and the temperature is maintained at 100-150°C in S3.

[0023] In a specific implementation manner, the mass concentration of the hydrogen peroxide in S2 is 10-15%.

[0024] In a specific embodiment, the mass content of sodium hypochlorite in S3 is 9-10%.

[0025] In a specific embodiment, the gaseous portion of the gas-liquid separation in S2 and S3 is preferably treated by alkaline solution absorption.

[0026] The method for treating COD in acetophenone-containing waste acid of the present invention is suitable for COD treatment and waste acid recovery of various acetophenone-containing waste acids. The treatment method of the present invention also has a good treatment effect on acetophenone-containing waste acid with high acidity and high COD. Preferably, the acidity content of the acetophenone-containing waste acid is 5-30%, and the COD content is 2000-50000 mg / L based on the mass of sulfuric acid.

[0027] Further preferably, the acidity of the waste acid containing acetophenone is 15-30%, and the COD content is 3000-50000 mg / L based on the mass of sulfuric acid.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The method for treating COD in acetophenone-containing waste acid of the present invention adopts two-stage continuous catalytic oxidation to treat high-acidity and high-COD waste acid, adopts hydrogen peroxide to carry out primary reaction oxidation on the purified acetophenone-containing waste acid, adopts sodium hypochlorite catalyzed by Ce-Mn-Mo-Cu homogeneous catalyst to carry out secondary oxidation on the acetophenone-containing waste acid after the primary reaction, and sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances under the condition of the acidity of the acetophenone-containing waste acid and the synergistic catalytic action of the catalyst to carry out secondary oxidation reaction on the waste acid itself, and the COD is synergistically controlled by the two oxidations to be efficiently oxidized to CO 2 Gases such as acetophenone can be recovered through alkaline solution absorption, and waste acid containing acetophenone can be recycled and utilized in the product production process. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0031] The specific component analysis of the waste acid containing acetophenone as the treatment object of the present invention is shown in Table 1 below:

[0032] Table 1

[0033]

[0034] Among them, the waste acids containing acetophenone 1 to 5 were used in Examples 1 to 5, respectively, and the waste acid containing acetophenone 5 was used in Comparative Examples 1 to 3.

[0035] The Ce-Mn-Mo-Cu homogeneous catalyst of the present invention is a self-made homogeneous catalyst, and the specific preparation method is as follows:

[0036] Cerium nitrate, manganese sulfate, ammonium molybdate and copper sulfate liquid are used for compounding, wherein the molar ratio of metal ions of Ce, Mn, Mo and Cu is 1:4:1.2:2.4.

[0037] Example 1

[0038] A method for treating COD in waste acid containing acetophenone comprises the following steps:

[0039] S1. The waste acid containing acetophenone is filtered and pretreated to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent clogging of the continuous reactor;

[0040] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature above 50°C, a peristaltic high-pressure pump is used to add 12% hydrogen peroxide to directly oxidize the waste acid containing acetophenone. The pressure of the system is maintained at 1MPa, the temperature is 80°C, and the residence time is 50s through a high-pressure one-way valve. Part of the COD is oxidized under this pressure system and then discharged into a gas-liquid separator. The oxidized CO 2 Separation of gas and waste acid containing acetophenone;

[0041] S3. The acetophenone-containing waste acid after the primary reaction is pumped into a secondary continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the temperature of the reactor system reaches 130° C., sodium hypochlorite with a hypochlorite mass content of 10% is added by a peristaltic high-pressure pump to perform secondary oxidation on the acetophenone-containing waste acid. The pressure of the system is maintained at 2.5 MPa and the temperature is maintained at 150° C. by a high-pressure one-way valve. The residence time is 100 s. Under the condition of the inherent acidity of the acetophenone-containing waste acid and the catalytic action of the catalyst, the sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances to perform secondary oxidation reaction on the waste acid itself. Most of the remaining COD will be oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for CO 2 The gas and waste acid are separated again, and the exhaust gas is absorbed by alkaline solution.

[0042] The reaction residence time of the waste acid containing acetophenone in the two-stage continuous reactor is about 150s, and the COD removal rate in the waste acid containing acetophenone can reach more than 94%. The separated waste acid is condensed through a heat exchanger, and the waste acid after cooling treatment is reused in the enterprise's product production process as a raw material for comprehensive resource utilization.

[0043] Example 2

[0044] A method for treating COD in waste acid containing acetophenone comprises the following steps:

[0045] S1. The waste acid containing acetophenone is filtered and pretreated to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent clogging of the continuous reactor;

[0046] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature above 50°C, a peristaltic high-pressure pump is used to add 12% hydrogen peroxide to directly oxidize the waste acid containing acetophenone. The pressure of the system is maintained at 1MPa, the temperature is 80°C, and the residence time is 50s through a high-pressure one-way valve. Part of the COD is oxidized under this pressure system and then discharged into a gas-liquid separator. The oxidized CO 2 Separation of gas and waste acid containing acetophenone;

[0047] S3. The acetophenone-containing waste acid after the primary reaction is pumped into a secondary continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the temperature of the reactor system reaches 130° C., sodium hypochlorite with a hypochlorite mass content of 10% is added by a peristaltic high-pressure pump to perform secondary oxidation on the acetophenone-containing waste acid. The pressure of the system is maintained at 1.5 MPa and the temperature is maintained at 150° C. by a high-pressure one-way valve. The residence time is 100 s. Under the condition of the inherent acidity of the acetophenone-containing waste acid and the catalytic action of the catalyst, the sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances to perform secondary oxidation reaction on the waste acid itself. Most of the remaining COD will be oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for CO 2 The gas and waste acid are separated again, and the exhaust gas is absorbed by alkaline solution.

[0048] The reaction residence time of the waste acid containing acetophenone in the two-stage continuous reactor is about 150s, and the COD removal rate in the waste acid containing acetophenone can reach more than 88%. The separated waste acid is condensed through a heat exchanger, and the waste acid after cooling treatment is reused in the enterprise's product production process as a raw material for comprehensive resource utilization.

[0049] Example 3

[0050] A method for treating COD in waste acid containing acetophenone comprises the following steps:

[0051] S1. The waste acid containing acetophenone is filtered and pretreated to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent clogging of the continuous reactor;

[0052] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature above 50°C, a peristaltic high-pressure pump is used to add 12% hydrogen peroxide to directly oxidize the waste acid containing acetophenone. The pressure of the system is maintained at 1MPa, the temperature is 80°C, and the residence time is 50s through a high-pressure one-way valve. Part of the COD is oxidized under this pressure system and then discharged into a gas-liquid separator. The oxidized CO 2 Separation of gas and waste acid containing acetophenone;

[0053] S3. The acetophenone-containing waste acid after the primary reaction is pumped into a secondary continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the temperature of the reactor system reaches 130° C., sodium hypochlorite with a hypochlorite mass content of 10% is added by a peristaltic high-pressure pump to perform secondary oxidation on the acetophenone-containing waste acid. The pressure of the system is maintained at 1MPa and the temperature is maintained at 150° C. by a high-pressure one-way valve. The residence time is 80s. Under the condition of the inherent acidity of the acetophenone-containing waste acid and the catalytic action of the catalyst, the sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances to perform secondary oxidation reaction on the waste acid itself. Most of the remaining COD will be oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for CO 2 The gas and waste acid are separated again, and the exhaust gas is absorbed by alkaline solution.

[0054] The reaction residence time of the waste acid containing acetophenone in the two-stage continuous reactor is about 130s, and the COD removal rate in the waste acid containing acetophenone can reach more than 75%. The separated waste acid is condensed through a heat exchanger, and the waste acid after cooling treatment is reused in the enterprise's product production process as a raw material for comprehensive resource utilization.

[0055] Example 4

[0056] A method for treating COD in waste acid containing acetophenone comprises the following steps:

[0057] S1. The waste acid containing acetophenone is filtered and pretreated to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent clogging of the continuous reactor;

[0058] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature above 50°C, a peristaltic high-pressure pump is used to add 12% hydrogen peroxide to directly oxidize the waste acid containing acetophenone. The pressure of the system is maintained at 0.5MPa, the temperature is 60°C, and the residence time is 50s through a high-pressure one-way valve. Part of the COD is oxidized under this pressure system and then discharged into a gas-liquid separator. The oxidized CO 2 Separation of gas and waste acid containing acetophenone;

[0059] S3. The acetophenone-containing waste acid after the primary reaction is pumped into a secondary continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the temperature of the reactor system reaches 130° C., sodium hypochlorite with a hypochlorite mass content of 10% is added by a peristaltic high-pressure pump to perform secondary oxidation on the acetophenone-containing waste acid. The pressure of the system is maintained at 2MPa and the temperature is 150° C. by a high-pressure one-way valve. The residence time is 80s. Under the condition of the inherent acidity of the acetophenone-containing waste acid and the catalytic action of the catalyst, the sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances to perform secondary oxidation reaction on the waste acid itself. Most of the remaining COD will be oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for CO 2 The gas and waste acid are separated again, and the exhaust gas is absorbed by alkaline solution.

[0060] The reaction residence time of the waste acid containing acetophenone in the two-stage continuous reactor is about 130s, and the COD removal rate in the waste acid containing acetophenone can reach more than 90%. The separated waste acid is condensed through a heat exchanger, and the waste acid after cooling treatment is reused in the enterprise's product production process as a raw material for comprehensive resource utilization.

[0061] Example 5

[0062] A method for treating COD in waste acid containing acetophenone comprises the following steps:

[0063] S1. The waste acid containing acetophenone is filtered and pretreated to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent clogging of the continuous reactor;

[0064] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature above 50°C, a peristaltic high-pressure pump is used to add 12% hydrogen peroxide to directly oxidize the waste acid containing acetophenone. The pressure of the system is maintained at 0.5MPa, the temperature is 60°C, and the residence time is 50s through a high-pressure one-way valve. Part of the COD is oxidized under this pressure system and then discharged into a gas-liquid separator. The oxidized CO 2 Separation of gas and waste acid containing acetophenone;

[0065] S3. The acetophenone-containing waste acid after the primary reaction is pumped into a secondary continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the temperature of the reactor system reaches 100° C., sodium hypochlorite with a hypochlorite mass content of 10% is added by a peristaltic high-pressure pump to perform secondary oxidation on the acetophenone-containing waste acid. The pressure of the system is maintained at 2.5 MPa and the temperature is 100° C. by a high-pressure one-way valve. The residence time is 80 seconds. Under the condition of the inherent acidity of the acetophenone-containing waste acid and the catalytic action of the catalyst, the sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances to perform secondary oxidation reaction on the waste acid itself. Most of the remaining COD will be oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for CO 2 The gas and waste acid are separated again, and the exhaust gas is treated by alkaline solution absorption;

[0066] S4. The reaction residence time of the waste acid containing acetophenone in the two-stage continuous reactor is about 130s, and the COD removal rate in the waste acid containing acetophenone can reach more than 78%. The separated waste acid is condensed through a heat exchanger, and the waste acid after cooling treatment is reused in the enterprise's product production process as a raw material for comprehensive resource utilization.

[0067] Comparative Example 1

[0068] A method for treating COD in waste acid containing acetophenone comprises the following steps:

[0069] S1. The waste acid containing acetophenone is filtered and pretreated to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent clogging of the continuous reactor;

[0070] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature above 50°C, a peristaltic high-pressure pump is used to add 12% hydrogen peroxide to directly oxidize the waste acid containing acetophenone. The pressure of the system is maintained at 1MPa, the temperature is 80°C, and the residence time is 50s through a high-pressure one-way valve. Part of the COD is oxidized under this pressure system and then discharged into a gas-liquid separator. The oxidized CO 2 Separation of gas and waste acid containing acetophenone;

[0071] S3. The acetophenone-containing waste acid after the primary reaction is directly pumped into a secondary continuous reactor by a high-pressure pump without adding a homogeneous catalyst. When the reactor system reaches a temperature of 130° C. or higher, sodium hypochlorite with a hypochlorite mass content of 10% is added by a peristaltic high-pressure pump to perform secondary oxidation on the acetophenone-containing waste acid. The pressure of the system is maintained at 2.5 MPa, the temperature is 150° C., and the residence time is 100 s by a high-pressure one-way valve. Under the condition of the inherent acidity of the acetophenone-containing waste acid, sodium hypochlorite decomposes to form chlorine dioxide and chlorine gas and other substances. Under the condition of no catalyst, the waste acid itself is subjected to secondary oxidation reaction. Part of the COD will be oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for CO 2 The gas and waste acid are separated again, and the exhaust gas is absorbed by alkaline solution.

[0072] The reaction residence time of the waste acid containing acetophenone in the two-stage continuous reactor is about 150s, and the COD removal rate of the waste acid containing acetophenone is about 48%.

[0073] Comparative Example 2

[0074] A method for treating COD in waste acid containing acetophenone comprises the following steps:

[0075] S1. The waste acid containing acetophenone is filtered and pretreated to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent clogging of the continuous reactor;

[0076] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature above 50°C, a peristaltic high-pressure pump is used to add 12% hydrogen peroxide to directly oxidize the waste acid containing acetophenone. The pressure of the system is maintained at 0.5MPa, the temperature is 60°C, and the residence time is 50s through a high-pressure one-way valve. Part of the COD is oxidized under this pressure system and then discharged into a gas-liquid separator. The oxidized CO 2 Separation of gas and waste acid containing acetophenone;

[0077] S3. The above-mentioned waste acid containing acetophenone after the primary reaction is directly pumped into a secondary continuous reactor by a high-pressure pump without adding a homogeneous catalyst. When the temperature of the reactor system reaches above 130° C., sodium hypochlorite with a hypochlorite mass content of 10% is added by a peristaltic high-pressure pump to perform secondary oxidation on the waste acid containing acetophenone. The pressure of the system is maintained at 2MPa, the temperature is 150° C., and the residence time is 80s by a high-pressure one-way valve. Under the condition of the inherent acidity of the waste acid containing acetophenone, sodium hypochlorite decomposes to form chlorine dioxide and chlorine gas and other substances. Under the condition of no catalyst, the waste acid itself is subjected to secondary oxidation reaction. Part of the COD will be oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for CO 2The gas and waste acid are separated again, and the exhaust gas is absorbed by alkaline solution.

[0078] The reaction residence time of the waste acid containing acetophenone in the two-stage continuous reactor is about 130 seconds, and the COD removal rate of the waste acid containing acetophenone is about 40%.

[0079] Comparative Example 3

[0080] A method for treating high-content COD in acetophenone-containing waste acid comprises the following steps:

[0081] S1. The waste acid containing acetophenone is filtered and pretreated to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent clogging of the continuous reactor;

[0082] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature above 50°C, a peristaltic high-pressure pump is used to add 12% hydrogen peroxide to directly oxidize the waste acid containing acetophenone. The pressure of the system is maintained at 1MPa and the temperature is maintained at 80°C by a high-pressure one-way valve. The residence time is 50S. Part of the COD is oxidized under this pressure system and then discharged into a gas-liquid separator. The oxidized CO 2 Separation of gas and waste acid containing acetophenone;

[0083] S3. The acetophenone-containing waste acid after the primary reaction is pumped into a secondary continuous reactor mixed with a homogeneous catalyst by a high-pressure pump again. When the reactor system reaches a temperature of 70° C. or higher, sodium hypochlorite with a hypochlorite mass content of 10% is added by a peristaltic high-pressure pump to perform secondary oxidation on the acetophenone-containing waste acid. The pressure of the system is maintained at 1 MPa and the temperature is maintained at 80° C. by a high-pressure one-way valve. The residence time is 100 s. Under the condition of the inherent acidity of the acetophenone-containing waste acid and the catalytic action of the catalyst, the sodium hypochlorite decomposes to form chlorine dioxide and chlorine gas and other substances to perform secondary oxidation reaction on the waste acid itself. Part of the COD will be oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for CO 2 The gas and waste acid are separated again, and the exhaust gas is absorbed by alkaline solution.

[0084] The reaction residence time of the waste acid containing acetophenone in the two-stage continuous reactor is 150S, and the COD removal rate in the waste acid containing acetophenone reaches 66%.

[0085] Results

[0086] The results of testing the COD-related indicators in the acetophenone-containing waste acid after treatment in the above examples and comparative examples are shown in Table 2.

[0087] The COD detection method adopts potassium dichromate reflux method.

[0088] Table 2.

[0089] Serial number COD before treatment (mg / L) COD after treatment (mg / L) Removal rate % Example 1 18982.5 1137.4 94.0％ Example 2 9681.7 1154.3 88.1％ Example 3 43867.3 10892.4 75.2％ Example 4 3236.1 315.8 90.2％ Example 5 12896.8 2819.1 78.1％ Comparative Example 1 12896.8 6730.9 47.8％ Comparative Example 2 12896.8 7717.3 40.2％ Comparative Example 3 12896.8 4378.5 66.0％

[0090] It can be seen from the results in Table 2 that the method for treating COD in acetophenone-containing waste acid of the present invention can effectively treat COD in acetophenone-containing waste acid with an acidity content of 5-30% and a COD content of 2000-50000 mg / L based on the mass of sulfuric acid, and the final COD removal rate is 78-94%, which has a significant COD removal effect.

[0091] The treatment conditions of Comparative Example 1 are basically the same as those of Example 1, except that Ce-Mn-Mo-Cu homogeneous catalyst is not added during the sodium hypochlorite oxidation process, and its COD removal rate is only 47.8%. The treatment conditions of Comparative Example 2 are basically the same as those of Example 4, except that Ce-Mn-Mo-Cu homogeneous catalyst is not added during the sodium hypochlorite oxidation process, and its final COD removal rate is only 40.2%. In Comparative Example 3, the temperature during the sodium hypochlorite oxidation process is too low, only 80°C, and it ultimately cannot achieve the COD removal effect of the present invention, and the COD removal rate is only 66.0%.

[0092] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, 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 embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for treating COD in waste acid containing acetophenone, characterized in that: The steps include: S1. Pretreating the waste acid containing acetophenone to remove insoluble impurities in the waste acid to obtain purified waste acid containing acetophenone; S2. The purified waste acid containing acetophenone is heated to above 50°C, hydrogen peroxide is added, the pressure of the system is maintained at 0.3-2MPa, the temperature is 50-100°C, and the gas-liquid separation is performed after the oxidation reaction to obtain the waste acid containing acetophenone in the primary reaction; S3. adding the waste acid containing acetophenone after the primary reaction into a reactor mixed with a Ce-Mn-Mo-Cu homogeneous catalyst, heating to above 70°C, adding sodium hypochlorite, sodium chlorate or potassium chlorate for secondary oxidation, the pressure of the system is 0.8-3MPa, the temperature is 90-150°C, the waste acid after the secondary oxidation is separated into gas and liquid, and the waste acid is condensed and reused, Among them, the total reaction time of S2 and S3 is 100-150s.

2. The method for treating COD in acetophenone-containing waste acid as claimed in claim 1, characterized in that: The oxidation reaction time in S2 is 30 to 80 seconds.

3. The method for treating COD in acetophenone-containing waste acid as claimed in claim 1, characterized in that: The oxidation reaction time in S2 is 50 s, and the secondary oxidation reaction time in S3 is 80 to 100 s.

4. The method for treating COD in waste acid containing acetophenone as claimed in claim 1, characterized in that: In S2, the system pressure is maintained at 0.5-1 MPa and the temperature is maintained at 60-80°C.

5. The method for treating COD in waste acid containing acetophenone as claimed in claim 1, characterized in that: In S3, the system pressure is maintained at 1-2.5 MPa and the temperature is maintained at 100-150°C.

6. The method for treating COD in acetophenone-containing waste acid according to claim 1, characterized in that: The mass concentration of the hydrogen peroxide in S2 is 10-15%.

7. The method for treating COD in acetophenone-containing waste acid according to claim 1, characterized in that: The mass content of hypochlorite in sodium hypochlorite in S3 is 9-10%.

8. The method for treating COD in acetophenone-containing waste acid according to claim 1, characterized in that: The gas portion of the gas-liquid separation in S2 and S3 is treated by alkaline solution absorption.

9. A method for treating COD in waste acid containing acetophenone according to any one of claims 1 to 8, characterized in that: The acidity of the acetophenone-containing waste acid is 5-30%, and the COD content is 2000-50000 mg / L based on the mass of sulfuric acid.

10. The method for treating COD in waste acid containing acetophenone according to claim 9, characterized in that: The acidity of the waste acid containing acetophenone is 15-30%, and the COD content is 3000-50000 mg / L based on the mass of sulfuric acid.

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