Method for treating COD in waste acid containing acetophenone

Abstract

The application discloses a method for treating COD in waste acid containing acetophenone and relates to the technical field of waste acid treatment. The method comprises the following steps: S1, pretreating the waste acid containing acetophenone; S2, carrying out gas-liquid separation on the waste acid containing acetophenone after purification and oxidation reaction to obtain the waste acid containing acetophenone after primary reaction; and S3, adding the waste acid containing acetophenone after primary reaction into sodium hypochlorite to carry out secondary oxidation, carrying out gas-liquid separation on the waste acid after secondary oxidation, and condensing and recycling the waste acid. According to the application, the COD is efficiently oxidized into CO2 and other gases through two times of oxidation and synergistic control, and the COD removal rate of the waste acid containing acetophenone can reach 94% at most, so that the waste acid containing acetophenone can be recycled and used in the product production process again.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste acid treatment, and more particularly to a method for treating COD in waste acid containing acetophenone. BACKGROUND

[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 the waste acid containing acetophenone is the by-product in the production process of pharmaceutical intermediates, which is generated in the Hooker 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 mainly caused by the by-product of intermediates. The COD value of the waste acid is often higher than 2000mg / L, and some even as high as tens of thousands of mg / L. Some waste acids also contain high concentrations of ammonia nitrogen and other pollutants. The waste acid contains ketone, aldehyde and other derivatives, and has low biodegradability, which is very unfavorable for the environment and recycling of waste acid. At present, many waste-producing enterprises can only use the neutralization method to precipitate and dispose of the residue by landfill or incineration, but this disposal method will cause a lot of subsequent environmental problems. Wet oxidation and wet catalytic oxidation are very effective technologies for treating medium and high concentration organic-containing waste acid, but in the environment of high acidity and high COD, the oxidation reaction in the conventional reactor has the following problems: first, there is a safety risk that the reaction may cause flash explosion; second, the controllability of the reaction is insufficient; third, the selection of the catalyst is not appropriate, and the oxidation capacity and oxidation effect cannot be guaranteed.

[0003] The prior art discloses a method for treating waste acid generated in the synthesis of m-nitroacetophenone, comprising the following steps: S1: extracting the waste acid generated in the nitration reaction of acetophenone with acetophenone at room temperature for 1-3 times to obtain waste acid A by liquid separation; S2: freezing and stirring the waste acid A at a temperature of-5℃ to-20℃, and filtering to obtain waste acid B; S3: distilling the waste acid B under negative pressure and at a temperature of 170-210℃ 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 400-1200mg / L. Although the prior art solution can also reduce the COD in the waste acid, it needs to be extracted, frozen at a low temperature of-5℃ to-20℃, and distilled at a high temperature of 170-210℃, which is not only complicated in operation, but also harsh in reaction conditions, and does not specify the treatment of high-acidity and high-COD waste acid containing acetophenone. SUMMARY

[0004] The present application aims to overcome the defects and deficiencies of the prior art that the reaction conditions are harsh, the steps are complicated, and the high-acidity and high-COD acetophenone-containing waste acid cannot be treated, and to provide a method for treating COD in acetophenone-containing waste acid, which solves the difficulty in treating a large amount of COD pollution factors in acetophenone-containing waste acid by using two-stage continuous catalytic oxidation, and realizes the recycling of acetophenone-containing waste acid.

[0005] The above-mentioned object of the present application is achieved by the following technical solutions.

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

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

[0008] S2. Heating the purified acetophenone-containing waste acid to above 50 DEG C, adding hydrogen peroxide, maintaining the pressure of the system at 0.3-2 MPa, and the temperature at 50-100 DEG C, and then gas-liquid separation after oxidation to obtain the acetophenone-containing waste acid after the first reaction;

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

[0010] The total reaction time of S2 and S3 is 100-150 s.

[0011] It should be noted that:

[0012] In S1, the acetophenone-containing waste acid is pretreated to remove insoluble impurities in the waste acid, purify the waste acid, and prevent the continuous reactor from being blocked.

[0013] In S2, hydrogen peroxide is used for the first reaction oxidation of the purified acetophenone-containing waste acid, and by controlling the reaction temperature and pressure, part of the COD is oxidized to CO2 gas under this pressure system, and the CO2 gas and the acetophenone-containing waste acid are separated after gas-liquid separation of the waste acid after the secondary oxidation.

[0014] The sodium hypochlorite is catalyzed by the Ce-Mn-Mo-Cu homogeneous catalyst in the S3 step to perform secondary oxidation on the waste acid containing acetophenone after the primary reaction, and the sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine and the like under the catalysis of the catalyst and the self acidity of the waste acid, so as to perform secondary oxidation on the waste acid, and most of the residual COD can be oxidized under the pressure system, and the waste acid after oxidation is separated into gas and liquid, and the gas such as CO2 and the waste acid are separated again.

[0015] In the primary reaction, hydrogen peroxide is used to remove the organic molecular impurities which are easy to react.

[0016] In the specific embodiment, the reaction of the present application is preferably performed in a reactor made of acid-resistant, oxidation-resistant, pressure-resistant and fast heat-conducting material, and the whole reaction process of the present application can be continuously performed.

[0017] In the specific embodiment, the filter in S1 is a filter bag with a mesh size of more than 1000, and the medium-pressure filtration is performed at 0.5 MPa, and when the pressure continuously increases, it indicates that the filter bag is blocked, and the filter bag needs to be replaced in time.

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

[0019] The method for removing COD in the waste acid containing acetophenone provided by the present application can remove 75-95% of the COD in the waste acid containing acetophenone in the two-stage continuous oxidation reaction, and the waste acid after separation is condensed through a heat exchanger, and the waste acid after cooling treatment is used as a resource comprehensive utilization raw material and is used in the product production process of the enterprise.

[0020] In the specific embodiment, preferably, the reaction time in S2 is 30-80 s.

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

[0022] In the specific embodiment, preferably, the system pressure in S2 is maintained at 0.5-1 MPa, and the temperature is 60-80℃.

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

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

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

[0026] The method for treating COD in acetophenone-containing waste acid of the present invention is applicable to the COD treatment and waste acid recovery of various acetophenone-containing waste acids. For acetophenone-containing waste acids with high acidity and high COD, the treatment method of the present invention also has good treatment effect. 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] More preferably, the acidity content of the acetophenone-containing waste acid 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 beneficial effects of the present invention are:

[0029] The present invention provides a method for treating COD in acetophenone-containing waste acid using a two-stage continuous catalytic oxidation process. First, hydrogen peroxide is used for the initial oxidation of the purified acetophenone-containing waste acid. Then, sodium hypochlorite, catalyzed by a Ce-Mn-Mo-Cu homogeneous catalyst, is used for a secondary oxidation of the acetophenone-containing waste acid after the initial reaction. Under the presence of the acetophenone-containing waste acid's own acidity and the synergistic catalytic action of the catalyst, sodium hypochlorite rapidly decomposes to form chlorine dioxide and chlorine gas, which then undergo a secondary oxidation reaction on the waste acid itself. Through this two-stage oxidation process, COD is efficiently oxidized into CO2 and other gases, which are then absorbed and recovered by alkaline solution. The acetophenone-containing waste acid can then be recycled and reused in the product manufacturing process. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, 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 acetophenone waste acid being treated by this invention is described in Table 1 below:

[0032] Table 1

[0033]

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

[0035] The Ce-Mn-Mo-Cu homogeneous catalyst of the present application 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 compounded, and the molar ratio of Ce, Mn, Mo and Cu metal ions is 1:4:1.2:2.4.

[0037] Example 1

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

[0039] S1. The acetophenone-containing waste acid is pretreated by filtration to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent the continuous reactor from being blocked;

[0040] S2. The purified acetophenone-containing waste acid is pumped into a first continuous reactor by a high-pressure pump, and when the heating system of the continuous reactor reaches a temperature of 50℃ or above, 12% mass concentration of hydrogen peroxide is added by a peristaltic high-pressure pump for direct oxidation of the acetophenone-containing waste acid, the pressure of the system is maintained at 1MPa by a high-pressure one-way valve, the temperature is 80℃, and the residence time is 50s, part of the COD is oxidized under this pressure system and discharged into a gas-liquid separator, and the CO2 gas and the acetophenone-containing waste acid after oxidation are separated;

[0041] S3. The acetophenone-containing waste acid after the above initial reaction is pumped into a second continuous reactor mixed with a homogeneous catalyst by a high-pressure pump, and when the reactor system reaches a temperature of 130℃, 10% mass content of sodium hypochlorite is added by a peristaltic high-pressure pump for secondary oxidation of the acetophenone-containing waste acid, the pressure of the system is maintained at 2.5MPa by a high-pressure one-way valve, the temperature is 150℃, and the residence time is 100s, the sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances under the condition of the self-acidity of the acetophenone-containing waste acid and the catalytic action of the catalyst, and the secondary oxidation reaction of the waste acid itself is carried out, most of the remaining COD is oxidized under this pressure system, the oxidized waste acid is discharged into a gas-liquid separator, and the CO2 gas and the waste acid are separated again, and the discharged gas is treated by alkali absorption.

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

[0043] Example 2

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

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

[0046] S2. The purified acetophenone-containing waste acid is pumped into a first continuous reactor by a high-pressure pump, and when the heating system of the continuous reactor reaches a temperature of 50℃ or above, 12% mass concentration of hydrogen peroxide is added by a peristaltic high-pressure pump for direct oxidation of the acetophenone-containing waste acid. The pressure of the system is maintained at 1MPa by a high-pressure one-way valve, the temperature is 80℃, and the residence time is 50s. Part of the COD is oxidized under this pressure system and discharged into a gas-liquid separator. The CO2 gas and the acetophenone-containing waste acid after oxidation are separated;

[0047] S3. The acetophenone-containing waste acid after the above primary reaction is pumped into a second continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the temperature of the reactor system reaches 130℃, 10% mass content of sodium hypochlorite is added by a peristaltic high-pressure pump for secondary oxidation of the acetophenone-containing waste acid. The pressure of the system is maintained at 1.5MPa by a high-pressure one-way valve, the temperature is 150℃, and the residence time is 100s. The 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 catalytic action of the catalyst, so as to perform secondary oxidation reaction on the waste acid. Most of the remaining COD is oxidized under this pressure system, and the oxidized waste acid is discharged into a gas-liquid separator for further separation of CO2 gas and waste acid. At the same time, the discharged gas is treated by alkali absorption.

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

[0049] Example 3

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

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

[0052] S2. The purified waste acid containing phenylacetone is pumped into a first continuous reactor by a high-pressure pump. When the temperature of the continuous reactor system reaches more than 50°C, 12% hydrogen peroxide is added to the waste acid containing phenylacetone by a peristaltic high-pressure pump for direct oxidation. The pressure of the system is maintained at 1 MPa by a high-pressure one-way valve, and the temperature is 80°C, and the residence time is 50 s. Part of the COD is oxidized under this pressure system and discharged into a gas-liquid separator. The CO2 gas and the waste acid containing phenylacetone after oxidation are separated.

[0053] S3. The waste acid containing phenylacetone after the first reaction is pumped into a second continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the temperature of the reactor system reaches 130°C, 10% sodium hypochlorite is added to the waste acid containing phenylacetone by a peristaltic high-pressure pump for secondary oxidation. The pressure of the system is maintained at 1 MPa by a high-pressure one-way valve, and the temperature is 150°C, and the residence time is 80 s. Sodium hypochlorite is rapidly decomposed to form chlorine dioxide and chlorine gas and other substances under the catalytic action of the catalyst in the presence of the acidity of the waste acid containing phenylacetone, and the waste acid itself is subjected to secondary oxidation reaction. Most of the remaining COD is oxidized under this pressure system, and the oxidized waste acid is discharged into a gas-liquid separator for further separation of CO2 gas and waste acid. At the same time, the discharged gas is treated by alkali absorption.

[0054] The residence time of the waste acid containing phenylacetone in the two-stage continuous reactor is about 130 s, and the COD removal rate of the waste acid containing phenylacetone can reach more than 75%. The separated waste acid is condensed by a heat exchanger, and the cooled waste acid is used as a raw material for resource comprehensive utilization in the production process of the enterprise.

[0055] Example 4

[0056] A method for treating COD in waste acid containing phenylacetone, comprising the following steps:

[0057] S1. The waste acid containing phenylacetone is pretreated by filtration to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent the continuous reactor from being blocked.

[0058] S2. The purified waste acid containing phenylacetone is pumped into a first continuous reactor by a high-pressure pump. When the temperature of the continuous reactor system reaches more than 50°C, 12% hydrogen peroxide is added to the waste acid containing phenylacetone by a peristaltic high-pressure pump for direct oxidation. The pressure of the system is maintained at 0.5 MPa by a high-pressure one-way valve, and the temperature is 60°C, and the residence time is 50 s. Part of the COD is oxidized under this pressure system and discharged into a gas-liquid separator. The CO2 gas and the waste acid containing phenylacetone after oxidation are separated.

[0059] S3. The above-mentioned primary reaction of the waste acid containing acetophenone is pumped into a secondary continuous reactor mixed with a homogeneous catalyst, and when the reactor system reaches a temperature of 130°C, a peristaltic high-pressure pump is used to add sodium hypochlorite with a mass content of 10% to the waste acid containing acetophenone for secondary oxidation. A high-pressure check valve is used to maintain the system pressure at 2 MPa, and the temperature is 150°C, and the residence time is 80 s. Under the condition of the self-acidity of the waste acid containing acetophenone and the catalytic action of the catalyst, sodium hypochlorite rapidly decomposes 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 further separation of CO2 gas and waste acid. At the same time, the discharged gas is treated by alkali absorption.

[0060] The reaction of the waste acid containing acetophenone in the two-stage continuous reactor has a residence time of about 130 s, and the COD removal rate of the waste acid containing acetophenone can reach more than 90%. The separated waste acid is condensed by a heat exchanger, and the cooled waste acid is used as a resource for comprehensive utilization of raw materials for product production in the enterprise.

[0061] Example 5

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

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

[0064] S2. The purified waste acid containing acetophenone is pumped into a continuous reactor by a high-pressure pump, and when the continuous reactor is heated to a temperature of more than 50°C, a peristaltic high-pressure pump is used to add hydrogen peroxide with a mass concentration of 12% to the waste acid containing acetophenone for direct oxidation. A high-pressure check valve is used to maintain the system pressure at 0.5 MPa, and the temperature is 60°C, and the residence time is 50 s. After part of the COD is oxidized under this pressure system, it is discharged into a gas-liquid separator for separation of CO2 gas and waste acid containing acetophenone after oxidation;

[0065] S3. The above-mentioned primary reaction of the waste acid containing phenylacetone is pumped into a secondary continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the reactor system reaches a temperature of 100°C, 10% sodium hypochlorite is added to the waste acid containing phenylacetone by a peristaltic high-pressure pump for secondary oxidation. The system pressure is maintained at 2.5 MPa by a high-pressure check valve, and the temperature is maintained at 100°C. The residence time is 80 s. Under the condition of the self-acidity of the waste acid containing phenylacetone and the catalytic action of the catalyst, sodium hypochlorite rapidly decomposes 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 is oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for further separation of CO2 gas and waste acid. At the same time, the discharged gas is treated by alkali absorption;

[0066] S4. The waste acid containing phenylacetone is reacted in a two-stage continuous reactor for about 130 s, and the COD removal rate of the waste acid containing phenylacetone can reach more than 78%. The separated waste acid is condensed by a heat exchanger. The cooled waste acid is used as a resource for comprehensive utilization of raw materials for product production in the enterprise.

[0067] Comparative Example 1

[0068] A method for treating COD in waste acid containing phenylacetone, comprising the following steps:

[0069] S1. The waste acid containing phenylacetone is pretreated by filtration to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent the continuous reactor from being blocked.

[0070] S2. The purified waste acid containing phenylacetone is pumped into a continuous reactor by a high-pressure pump. When the continuous reactor is heated to a temperature of more than 50°C, 12% hydrogen peroxide is added to the waste acid containing phenylacetone by a peristaltic high-pressure pump for direct oxidation. The system pressure is maintained at 1 MPa by a high-pressure check valve, and the temperature is maintained at 80°C. The residence time is 50 s. Part of the COD is oxidized under this pressure system and discharged into a gas-liquid separator for separation of CO2 gas and waste acid containing phenylacetone after oxidation.

[0071] S3. The above-mentioned primary reaction of the waste acid containing acetophenone is pumped into the 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 mass content of 10% is added to the waste acid containing acetophenone by a peristaltic high-pressure pump for secondary oxidation. The pressure of the system is maintained at 2.5 MPa by a high-pressure one-way valve, and the temperature is 150°C. The residence time is 100 s. In the presence of the acidity of the waste acid containing acetophenone, sodium hypochlorite decomposes to form chlorine dioxide, chlorine gas and other substances. Without a catalyst, the waste acid itself is subjected to secondary oxidation. Part of the COD is oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for further separation of CO2 gas and waste acid. The discharged gas is treated by alkali absorption.

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

[0073] Comparative Example 2

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

[0075] S1. The waste acid containing acetophenone is pretreated by filtration to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent the continuous reactor from being blocked.

[0076] S2. The purified waste acid containing acetophenone is pumped into a primary continuous reactor by a high-pressure pump. When the heating system of the continuous reactor reaches a temperature of 50°C or higher, hydrogen peroxide with a mass concentration of 12% is added to the waste acid containing acetophenone by a peristaltic high-pressure pump for direct oxidation. The pressure of the system is maintained at 0.5 MPa by a high-pressure one-way valve, and the temperature is 60°C. The residence time is 50 s. Part of the COD is oxidized under this pressure system and discharged into a gas-liquid separator for separation of CO2 gas and the waste acid containing acetophenone after oxidation.

[0077] S3. The above-mentioned primary reaction of the waste acid containing acetophenone is pumped into the 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 mass content of 10% is added to the waste acid containing acetophenone by a peristaltic high-pressure pump for secondary oxidation. The pressure of the system is maintained at 2.5 MPa by a high-pressure one-way valve, and the temperature is 150°C. The residence time is 100 s. In the presence of the acidity of the waste acid containing acetophenone, sodium hypochlorite decomposes to form chlorine dioxide, chlorine gas and other substances. Without a catalyst, the waste acid itself is subjected to secondary oxidation. Part of the COD is oxidized under this pressure system. The oxidized waste acid is discharged into a gas-liquid separator for further separation of CO2 gas and waste acid. The discharged gas is treated by alkali absorption.

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

[0079] Comparative Example 3

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

[0081] S1. The acetophenone-containing waste acid is pretreated by filtration to remove a large amount of impurities in the waste acid, so as to purify the waste acid and prevent the continuous reactor from being blocked;

[0082] S2. The purified acetophenone-containing waste acid is pumped into a first-stage continuous reactor by a high-pressure pump, and when the heating system of the continuous reactor reaches a temperature of more than 50℃, 12% mass concentration of hydrogen peroxide is added to the acetophenone-containing waste acid by a peristaltic high-pressure pump for direct oxidation. The pressure of the system is maintained at 1 MPa by a high-pressure one-way valve, and the temperature is 80℃. The residence time is 50 s. Part of the COD is oxidized under this pressure system and discharged into a gas-liquid separator. The CO2 gas and the acetophenone-containing waste acid after oxidation are separated.

[0083] S3. The acetophenone-containing waste acid after the first reaction is pumped into a second-stage continuous reactor mixed with a homogeneous catalyst by a high-pressure pump. When the reactor system reaches a temperature of more than 70℃, 10% mass content of sodium hypochlorite is added to the acetophenone-containing waste acid by a peristaltic high-pressure pump for secondary oxidation. The pressure of the system is maintained at 1 MPa by a high-pressure one-way valve, and the temperature is 80℃. The residence time is 100 s. The sodium hypochlorite is decomposed to form chlorine dioxide and chlorine gas and other substances under the condition of the self-acidity of the acetophenone-containing waste acid and the catalytic action of the catalyst, so as to perform secondary oxidation reaction on the waste acid itself. Part of the COD is oxidized under this pressure system, and the oxidized waste acid is discharged into a gas-liquid separator for further separation of CO2 gas and waste acid. At the same time, the discharged gas is treated by alkali absorption.

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

[0085] Results detection

[0086] The COD related indexes of the acetophenone-containing waste acid treated 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 No. COD (mg / L) before treatment COD (mg / L) after treatment % removal 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] From the results of Table 2 above, it can be seen that the method for treating COD in waste acid containing acetophenone according to the present application can effectively treat waste acid containing acetophenone with an acidity content of 5-30% by mass of sulfuric acid and a COD content of 2000-50000 mg / L, and the final COD removal rate is 78-94%, which has a significant COD removal effect.

[0091] Comparative Example 1 and Example 1 have basically the same treatment conditions, except that no Ce-Mn-Mo-Cu homogeneous catalyst is added in the sodium hypochlorite oxidation process, and the COD removal rate is only 47.8%. Comparative Example 2 and Example 4 have basically the same treatment conditions, except that no Ce-Mn-Mo-Cu homogeneous catalyst is added in the sodium hypochlorite oxidation process, and the final COD removal rate is also only 40.2%. In Comparative Example 3, the temperature in the sodium hypochlorite oxidation process is too low, only 80°C, and the final COD removal rate is also only 66.0%, which cannot achieve the COD removal effect of the present application.

[0092] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. It is not necessary or possible to exhaust all embodiments here. Any modification, equivalent replacement and improvement made within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for treating COD in acetophenone-containing waste acid, characterized in that, Includes the following steps: S1. Pre-treat the acetophenone-containing waste acid to remove insoluble impurities from the waste acid and obtain purified acetophenone-containing waste acid; S2. Heat the purified acetophenone-containing waste acid to above 50°C, add hydrogen peroxide, maintain the system pressure at 0.3-2MPa and the temperature at 50-100°C, and after the oxidation reaction, separate the gas and liquid to obtain the acetophenone-containing waste acid from the first reaction. S3. The acetophenone-containing waste acid from the initial reaction is added to a reactor containing a Ce-Mn-Mo-Cu homogeneous catalyst. The mixture is heated to above 70°C, and sodium hypochlorite, sodium chlorate, or potassium chlorate are added for secondary oxidation. The system pressure is 1.5-3 MPa, and the temperature is 90-150°C. The waste acid after secondary oxidation undergoes gas-liquid separation, and the waste acid is condensed and reused. The total reaction time for S2 and S3 is 100-150 seconds. The preparation method of the Ce-Mn-Mo-Cu homogeneous catalyst is as follows: Cerium nitrate, manganese sulfate, ammonium molybdate and copper sulfate liquid are compounded, wherein the molar ratio of metal ions of Ce, Mn, Mo and Cu is 1:4:1.2:2.

4.

2. The method for treating COD in acetophenone-containing waste acid as described in claim 1, characterized in that, The oxidation reaction time in S2 is 30–80 s.

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

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

5. The method for treating COD in acetophenone-containing waste acid as described in claim 1, characterized in that, In S3, the system pressure is maintained at 1.5–2.5 MPa and the temperature at 100–150 °C.

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

7. The method for treating COD in acetophenone-containing waste acid as described in claim 1, characterized in that, The sodium hypochlorite in S3 contains 9-10% hypochlorite by mass.

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

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

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