Wastewater treatment methods for p-tert-butylbenzoic acid production

Abstract

This invention provides a method for treating wastewater from the production of p-tert-butylbenzoic acid, belonging to the field of industrial wastewater treatment. The method includes: homogenizing and adjusting the p-tert-butylbenzoic acid production wastewater; adjusting the pH to 5-6, adding hydrogen peroxide and a catalyst, and introducing oxygen-containing gas for a wet oxidation reaction; the waste gas generated from the reaction is purified in a desulfurization and denitrification reactor; the catalyst is prepared by mixing carbon-doped metal oxides TiO2@C, CuO@C, and Fe2O3@C, and uniformly dispersing them in a 1%-3% amphiphilic polymer solution under ice bath conditions to form a suspension; the suspension is subjected to a hydrothermal reaction at 100℃-150℃ for 3-6 hours, followed by static solidification, solid-liquid separation, and solid drying to obtain a catalyst precursor; the precursor is then impregnated in an amphiphilic polymer solution, dried at low temperature, and then sintered at high temperature. This invention effectively treats p-tert-butylbenzoic acid production wastewater based on a wet oxidation reaction, efficiently removing benzene and nitrogen / sulfur pollutants, thus promoting environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment technology, and specifically relates to a method for treating wastewater from the production of p-tert-butylbenzoic acid. Background Technology

[0002] p-tert-butylbenzoic acid is widely used in chemical synthesis, pharmaceuticals, cosmetics, fragrances, and pharmaceutical production. Its production process is as follows: The basic production process includes: using p-tert-butyltoluene and oxygen as raw materials, crude p-tert-butylbenzoic acid is obtained through catalytic oxidation, followed by cooling crystallization, centrifugation, washing, recrystallization, decolorization, water washing, centrifugation, and drying to obtain the finished p-tert-butylbenzoic acid. The above production process generates a large amount of wastewater, the main component of which is benzene-based organic matter. It has the disadvantages of high organic matter concentration (initial COD concentration generally exceeds 20,000 mg / L) and poor biodegradability. Conventional physicochemical or biochemical methods are difficult to effectively remove the pollutants. In addition, the wastewater has a complex composition and also contains sulfides, nitrogen oxides, etc.

[0003] Existing research involves pretreating wastewater using methods such as oxidation to improve its biodegradability, breaking down large, recalcitrant organic molecules into low-molecular-weight acids and alcohols. Advanced oxidation technologies are widely used to treat benzene-based organic pollutants, and mainly include ozone oxidation, wet air oxidation, photocatalytic oxidation, electrochemical oxidation, Fenton oxidation, and persulfate oxidation.

[0004] Wet air oxidation (WAO) technology involves introducing O2 or air into polluted water at high temperatures (150-350℃) and high pressures (0.5-20MPa) to degrade pollutants. The disadvantages of this technology include high equipment requirements and significant investment, operation, and maintenance costs. Adding catalysts can lower the reaction temperature and pressure, thereby reducing the activation energy, lowering equipment costs, and improving pollutant treatment efficiency. However, wet catalytic air oxidation also faces several challenges: precious metal catalysts are effective but expensive, and there are issues with catalyst loss and deactivation.

[0005] Currently, the catalysts used in wet air oxidation processes for industrial organic wastewater are a combination of active metal catalysts and chain organic catalysts. For example, metal catalysts with metals such as aluminum, iron, manganese, cerium, copper, chromium, nickel, silver, and zinc as active components, as well as organic compounds (such as organic calcium / magnesium salts and azo compounds supported on a carrier). It has the following drawbacks: (1) It is suitable for industrial wastewater with low COD concentration, such as initial COD concentration below 10,000 mg / L. It has poor treatment effect on high-concentration industrial organic wastewater. (2) The wastewater containing tert-butylbenzoic acid also contains sulfides and other substances, which will further reduce the catalytic efficiency. (3) The wet air oxidation reaction requires a relatively high temperature, generally between 200℃ and 250℃. Summary of the Invention

[0006] Therefore, the present invention aims to provide a method for treating wastewater from the production of p-tert-butylbenzoic acid, in order to solve at least one of the technical problems in the background art.

[0007] This invention is implemented as follows:

[0008] A method for treating wastewater from the production of p-tert-butylbenzoic acid, the method comprising the following steps:

[0009] The wastewater from the production of tert-butylbenzoic acid will be homogenized and adjusted.

[0010] Adjust the pH of the production wastewater to 5-6, add an initiator, introduce oxygen-containing gas, and carry out a wet oxidation reaction at 160℃-200℃, 1Mpa-10Mpa and under continuous stirring conditions.

[0011] The waste gas generated by the wet oxidation reaction enters the desulfurization and denitrification reactor for purification treatment;

[0012] The initiator comprises hydrogen peroxide and a catalyst, wherein the catalyst is a carbon-doped titanium-copper-iron composite oxide; the catalyst is prepared by:

[0013] Carbon-doped metal oxides TiO2@C, CuO@C, and Fe2O3@C were prepared respectively.

[0014] TiO2@C, CuO@C, and Fe2O3@C are mixed and then uniformly dispersed in an amphiphilic polymer solution with a mass concentration of 1% to 3% under ice bath conditions to form a suspension; the amphiphilic polymer solution is a solution formed by dissolving the amphiphilic polymer in an organic solvent;

[0015] The suspension was subjected to hydrothermal reaction at 100℃~150℃ for 3h~6h, and after the reaction, it was allowed to stand and solidify, then the solid was separated and dried to obtain the catalyst precursor.

[0016] The catalyst precursor was impregnated in a 5%–10% amphiphilic polymer solution for 5–20 seconds, dried and cured at a low temperature of 50–60°C, and the impregnation and low-temperature drying were repeated at least once. Then, the precursor was sintered at a high temperature of 400–600°C under a protective atmosphere for 1–2 hours to obtain carbon-doped titanium-copper-iron composite oxide.

[0017] Furthermore, the oxygen-containing gas is introduced in batches and intermittently. Specifically, after the oxygen-containing gas is introduced for wet oxidation reaction, the waste gas is discharged 15 to 30 minutes later. After the exhaust is completed, the oxygen-containing gas is introduced again for wet oxidation reaction, and the cycle is repeated.

[0018] Furthermore, the preparation steps of the carbon-doped metal oxides TiO2@C, CuO@C, and Fe2O3@C are as follows:

[0019] Citric acid and surfactant are mixed in a mass ratio of 5 to 15:1 and dissolved in water to prepare a carbon source solution;

[0020] The TiO2, CuO, and Fe2O3 powders were respectively immersed in a carbon source solution and heated to 150℃~170℃ for 10~30h.

[0021] After the reaction was completed, the solid and liquid were separated, and the precipitate obtained after repeated rinsing of the solid was dried under vacuum.

[0022] Under a protective atmosphere, the dried solid is sintered at 500℃~700℃ for 1h~2h to obtain carbon-doped metal oxide.

[0023] Furthermore, the surfactant is a quaternary ammonium salt surfactant.

[0024] Furthermore, the amphiphilic polymer is a fluorinated amphiphilic polymer; the organic solvent is tetrahydrofuran.

[0025] Furthermore, according to the molar ratio, the Ti:Cu:Fe ratio in the carbon-doped titanium-copper-iron composite oxide is 1:1:10 to 30.

[0026] Furthermore, the liquid-to-solid ratio during the preparation of the suspension is (5-10) ml: 1 mg.

[0027] Furthermore, the waste gas generated by the wet oxidation reaction enters the desulfurization and denitrification reactor for purification treatment. The specific steps are as follows:

[0028] The waste gas is fed into the desulfurization and denitrification reactor from the bottom, where it comes into countercurrent contact with the absorbent liquid sprayed down for primary purification.

[0029] The solid absorption bed built into the upper part of the desulfurization and denitrification reactor performs secondary purification of the gas;

[0030] The absorbent is a calcium or sodium salt solution; the packing material for the solid absorption bed is a molecular sieve or activated carbon.

[0031] Furthermore, the amount of hydrogen peroxide used is 0.05% to 0.2% of the wastewater volume.

[0032] Furthermore, the wet oxidation reaction time is 1h to 2h.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. This invention effectively treats wastewater from the production of p-tert-butylbenzoic acid using a wet oxidation reaction, efficiently removing benzene and nitrogen and sulfur pollutants, thus promoting environmental protection.

[0035] 2. This invention uses carbon-doped titanium-copper-iron composite oxide as a catalyst, with MO... x @C (M is a metal) combines with amphiphilic polymers to form a porous membrane with hydrophilic and oleophilic properties, which enables the degradation efficiency of high concentrations of COD to be above 99.8%, while also effectively degrading nitrogen and sulfur.

[0036] 3. The wet oxidation reaction of this invention adopts intermittent ventilation and exhaust, so that the catalytic reaction and the adsorption and degradation of waste gas are treated simultaneously, further improving the pollutant removal efficiency.

[0037] 4. This invention is based on wet oxidation reaction for treatment, which has a high temperature of waste gas and can recover waste heat, which is beneficial to resource reuse. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] The method for treating wastewater from the production of p-tert-butylbenzoic acid includes the following steps:

[0040] S1. Homogenize and adjust the wastewater from the production of tert-butylbenzoic acid.

[0041] During the production of p-tert-butylbenzoic acid, the types and concentrations of pollutants discharged from wastewater vary at different times and in different equipment / engineering sections due to factors such as process and time. Direct treatment is difficult to control and affects the treatment effect.

[0042] S2. Adjust the pH of the production wastewater to 5-6, add an initiator, introduce oxygen-containing gas, and carry out a wet oxidation reaction at 160℃-200℃, 1Mpa-10Mpa and under continuous stirring.

[0043] In practice, the oxygen-containing gas is air or pure oxygen. In actual engineering, air is generally used to save costs, with the oxygen in it as the oxidant. The amount used is adjusted according to the COD of the wastewater. For example, for 1L of production wastewater, the total amount of air used is 50L to 80L.

[0044] The initiator includes hydrogen peroxide and a catalyst, wherein the catalyst is a carbon-doped titanium-copper-iron composite oxide. The oxidation reaction in wet oxidation is a free radical reaction, undergoing an induction phase, a proliferation phase, a degradation phase, and a termination phase. The rate of wet oxidation is limited by the concentration of free radicals. During the induction phase, the initial rate of free radical formation is slow; therefore, adding an initiator to promote free radical initiation can accelerate the process.

[0045] In practical implementation, the catalyst of this invention degrades the recalcitrant organic matter in the wastewater from the production of p-tert-butylbenzoic acid into small-molecule organic matter, carbon dioxide, and water. Simultaneously, it catalytically decomposes the sulfur element at high temperature to form gaseous sulfides such as hydrogen sulfide and SO₂. X Since sulfides can inhibit the wet oxidation reaction rate if they are present in the solution for a long time, this invention uses intermittent batch introduction of oxygen-containing gas and intermittent batch discharge of waste gas. Specifically, after the wet oxidation reaction is carried out with oxygen-containing gas, the waste gas is discharged 15 to 30 minutes later. After the discharge is completed, oxygen-containing gas is introduced again for wet oxidation reaction, and the cycle is repeated.

[0046] In practice, the amount of hydrogen peroxide used is 0.05% to 0.2% of the wastewater volume, which can be 0.05%, 0.1%, or 0.2%; however, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0047] In practice, the wet oxidation reaction time is 1 to 2 hours, which can be 1 hour, 1.5 hours, or 2 hours; however, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0048] Research has shown that, under the initiator conditions of this invention, a slightly acidic pH in the generated wastewater is more conducive to the efficient catalytic effect.

[0049] S3. The waste gas generated by the wet oxidation reaction enters the desulfurization and denitrification reactor for purification treatment.

[0050] Specifically, the waste gas is fed into the desulfurization and denitrification reactor from the bottom, where it comes into countercurrent contact with the sprayed absorbent liquid for primary purification. A solid absorption bed built into the upper part of the reactor then performs secondary purification. The absorbent liquid is a calcium or sodium salt solution, such as calcium chloride solution and / or sodium chloride solution. The packing material for the solid absorption bed is molecular sieves or activated carbon. The main components of the waste gas are carbon dioxide and a certain amount of sulfur- and nitrogen-containing waste gas.

[0051] In practice, the spraying device for the absorbent liquid is installed below the solid absorption bed. The exhaust gas discharged from the wet oxidation reaction is high-temperature waste gas containing sulfur and nitrogen. The calcium chloride solution and / or sodium chloride solution react with SO2 in the gas. x NO x The reaction produces calcium sulfate / sodium sulfate or calcium sulfite / sodium sulfate solution, and calcium nitrate / sodium nitrate solution, which are then discharged. Unreacted gaseous pollutants continue to rise, passing through the solid absorption bed where they are absorbed by the packing material. Finally, the purified gas is discharged from the top of the desulfurization and denitrification reactor. Because the purified gas still has a relatively high temperature, waste heat recovery can be performed, for example, by introducing the purified gas into a waste heat boiler to participate in the boiler combustion reaction.

[0052] This invention removes sulfur- and nitrogen-containing waste gases generated during the wet oxidation process in stages, preventing their accumulation from affecting the wet oxidation process and the reaction environment.

[0053] In practice, wastewater treated by wet oxidation can be discharged directly or mixed with domestic sewage for subsequent biochemical treatment.

[0054] The preparation method of the carbon-doped titanium-copper-iron composite oxide catalyst in the wet oxidation reaction is as follows:

[0055] (1) Prepare carbon-doped metal oxides TiO2@C, CuO@C, and Fe2O3@C respectively;

[0056] Citric acid and a surfactant are mixed in a mass ratio of 5 to 15:1 and dissolved in water to prepare a carbon source solution. Specifically, a quaternary ammonium salt surfactant is used. The following examples use hexadecyltrimethylammonium bromide for illustration, but it is not limited to this surfactant. Other unlisted quaternary ammonium salt surfactants are also applicable.

[0057] TiO2, CuO, and Fe2O3 powders are respectively immersed in a carbon source solution and heated to 150℃~170℃ for 10h~30h. In specific implementations, the temperature can be 150℃, 160℃, or 170℃, and the reaction time can be 10h, 20h, or 30h. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0058] After the reaction, the solid and liquid are separated, and the precipitate obtained after repeated washing of the solid is vacuum dried. Under a protective atmosphere, the dried solid is sintered at 500℃~700℃ for 1h~2h to obtain carbon-doped metal oxide. In specific implementation, the temperature can be 500℃, 600℃, or 700℃, and the reaction time can be 1h, 1.5h, or 2h; but it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0059] (2) TiO2@C, CuO@C and Fe2O3@C are mixed and uniformly dispersed in an amphiphilic polymer solution with a mass concentration of 1% to 3% under ice bath conditions to form a suspension; the suspension is kept at 100℃ to 150℃ for 3h to 6h for hydrothermal reaction, and after the reaction, it is allowed to stand and solidify, the solid and liquid are separated, and the solid is dried to obtain the catalyst precursor;

[0060] The amphiphilic polymer solution is a solution formed by dissolving an amphiphilic polymer in an organic solvent; the amphiphilic polymer is a fluorinated amphiphilic polymer, and the organic solvent is tetrahydrofuran; the following examples use a fluorinated amphiphilic polymer copolymerized with polyethylene glycol as the hydrophilic segment and dodecyl fluoroheptyl methacrylate as the lipophilic segment as shown in formula (Ⅰ), but it is not limited to this amphiphilic polymer, and other unlisted fluorinated amphiphilic polymers are also applicable;

[0061]

[0062] In specific implementation, the liquid-to-solid ratio of the suspension is (5-10) ml:1 mg, which can be 5:1, 7:1, or 10:1; but it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0063] In specific implementation, according to the molar ratio, the Ti:Cu:Fe ratio in the carbon-doped titanium-copper-iron composite oxide in the suspension is 1:1:10 to 30, which can be 1:1:10, 1:1:20, or 1:1:30; but it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0064] (3) The catalyst precursor is immersed in an amphiphilic polymer solution with a mass concentration of 5% to 10% for 5s to 20s, dried and cured at a low temperature of 50℃ to 60℃, and the immersion and low temperature drying are repeated at least once. Then, the catalyst is sintered at a high temperature of 400℃ to 600℃ under a protective atmosphere for 1h to 2h to obtain carbon-doped titanium-copper-iron composite oxide.

[0065] In practical applications, amphiphilic polymers possess both hydrophilic and lipophilic chains, exhibiting strong aggregation characteristics. Introducing amphiphilic polymers into the matrix of metal oxides facilitates the aggregation and deposition of metal oxides. Furthermore, hydrothermal reactions can form a film-like substance on the surface of the aggregates, which is then sintered at high temperatures to form a porous membrane. Compared to other hydrocarbon analogs, fluorinated amphiphilic polymers exhibit a stronger tendency to aggregate due to the higher hydrophobicity, lower solubility, and stronger stability of fluorinated groups, making them more conducive to the aggregation of TiO2@C, CuO@C, and Fe2O3@C.

[0066] Using a higher concentration of amphiphilic polymer for rapid and brief impregnation before high-temperature sintering is beneficial for forming a uniform coating thickness and improves the stability of metal oxide deposition.

[0067] Example 1

[0068] Example 1 describes the preparation of a catalyst for treating wastewater from the production of p-tert-butylbenzoic acid. The specific steps for preparing the catalyst are as follows:

[0069] 1. Preparation of TiO2@C, CuO@C, Fe2O3@C

[0070] Citric acid and hexadecyltrimethylammonium bromide were mixed in a mass ratio of 10:1, dissolved in water, and ultrasonically dispersed to obtain a uniformly mixed carbon source solution.

[0071] TiO2 powder was immersed in a carbon source solution, heated to 150℃ and kept at that temperature for 30 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. TiO2@C was obtained by sintering at 700℃ for 1.5 hours under a protective atmosphere.

[0072] CuO powder was immersed in a carbon source solution, heated to 160℃ and kept at that temperature for 24 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. CuO@C was obtained by sintering at 700℃ for 1.5 hours under a protective atmosphere.

[0073] Fe2O3 powder was immersed in a carbon source solution, heated to 170℃ and kept at that temperature for 15 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. The solid was then sintered at 700℃ for 1.5 hours under a protective atmosphere to obtain Fe2O3@C.

[0074] 2. Dissolve the fluorinated amphiphilic polymer as shown in formula (Ⅰ) in tetrahydrofuran to prepare an amphiphilic polymer solution; mix TiO2@C, CuO@C, and Fe2O3@C in a molar ratio of 1:1:20 to form a metal powder; mix the 2% amphiphilic polymer solution and the metal powder in an ice bath under ice bath conditions and homogenize them in a homogenizing device to form a suspension; then keep it at 120℃ for hydrothermal reaction for 5 hours; after the reaction, let it stand to solidify, separate the solid and liquid, and dry the solid to obtain the catalyst precursor;

[0075] 3. The catalyst precursor was impregnated in a 10% (w / w) amphiphilic polymer solution for 5 seconds, dried and cured at 50°C, and the impregnation and low-temperature drying were repeated twice. Then, the precursor was sintered at 500°C under a protective atmosphere for 1.5 hours to obtain a carbon-doped titanium-copper-iron composite oxide, which was used as a catalyst.

[0076] The catalyst prepared in Example 1 was used to treat wastewater from the production of p-tert-butylbenzoic acid. The specific steps are as follows:

[0077] S1. The wastewater from the production of p-tert-butylbenzoic acid will be homogenized and adjusted; the wastewater originates from the wastewater generated during the production of p-tert-butylbenzoic acid by Jiangxi Yongtong Technology Co., Ltd.

[0078] S2. The catalyst prepared in Example 1 is loaded into an air wet oxidation reactor. The pH of the production wastewater is adjusted to 5, and hydrogen peroxide is added at a volume ratio of 0.05%. After mixing, the mixture is fed into the air wet oxidation reactor for wet oxidation reaction. The reaction temperature is set at 200℃ and the pressure at 10 MPa. Specifically, air is introduced at a ratio of 20 L O2 / 1 L wastewater. After reacting for 30 minutes, the waste gas generated by the air wet oxidation reactor is discharged to proceed to the next stage. After venting, air is continuously introduced to circulate the wet oxidation reaction and exhaust gas. The total reaction time is 2 hours.

[0079] S3. The waste gas generated in step S2 is fed into the desulfurization and denitrification reactor from the bottom and comes into countercurrent contact with the calcium chloride solution sprayed down for primary purification; the solid absorption bed (filler is molecular sieve) built into the upper part of the desulfurization and denitrification reactor performs secondary purification of the gas.

[0080] Example 2

[0081] The only difference between Example 2 and Example 1 is the catalyst preparation, and the specific steps are as follows:

[0082] 1. Preparation of TiO2@C, CuO@C, Fe2O3@C

[0083] Citric acid and hexadecyltrimethylammonium bromide were mixed in a mass ratio of 5:1, dissolved in water, and ultrasonically dispersed to obtain a homogeneous carbon source solution.

[0084] TiO2 powder was immersed in a carbon source solution, heated to 150℃ and kept at that temperature for 24 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. TiO2@C was obtained by sintering at 500℃ for 2 hours under a protective atmosphere.

[0085] CuO powder was immersed in a carbon source solution, heated to 150°C and kept at that temperature for 24 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. CuO@C was obtained by sintering at 500°C for 2 hours under a protective atmosphere.

[0086] Fe2O3 powder was immersed in a carbon source solution, heated to 150℃ and kept at that temperature for 24 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. The solid was then sintered at 500℃ for 2 hours under a protective atmosphere to obtain Fe2O3@C.

[0087] 2. Dissolve the fluorine-containing amphiphilic polymer as shown in formula (Ⅰ) in tetrahydrofuran to prepare an amphiphilic polymer solution; mix TiO2@C, CuO@C, and Fe2O3@C in a molar ratio of 1:1:10 to form a metal powder; mix the 1% amphiphilic polymer solution and the metal powder in an ice bath at a liquid-solid ratio of 5 ml:1 mg to form a suspension; then keep the suspension at 100°C for 6 h for hydrothermal reaction; after the reaction, allow it to stand and solidify, separate the solid and liquid, and dry the solid to obtain the catalyst precursor;

[0088] 3. The catalyst precursor was immersed in a 5% (w / w) amphiphilic polymer solution for 20 seconds, dried and cured at 50°C, and the immersion and low-temperature drying were repeated once. Then, the precursor was sintered at 500°C under a protective atmosphere for 2 hours to obtain a carbon-doped titanium-copper-iron composite oxide, which was used as a catalyst.

[0089] The treatment steps for the production wastewater of tert-butylbenzoic acid in this embodiment are the same as those in Example 1.

[0090] Example 3

[0091] The only difference between Example 3 and Example 1 is the catalyst preparation, and the specific steps are as follows:

[0092] 1. Preparation of TiO2@C, CuO@C, Fe2O3@C

[0093] Citric acid and hexadecyltrimethylammonium bromide were mixed in a mass ratio of 7:1, dissolved in water, and ultrasonically dispersed to obtain a homogeneous carbon source solution.

[0094] TiO2 powder was immersed in a carbon source solution, heated to 150℃ and kept at that temperature for 24 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. TiO2@C was obtained by sintering at 600℃ for 1 hour under a protective atmosphere.

[0095] CuO powder was immersed in a carbon source solution, heated to 150°C and kept at that temperature for 24 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. CuO@C was obtained by sintering at 600°C for 1 hour under a protective atmosphere.

[0096] Fe2O3 powder was immersed in a carbon source solution, heated to 150℃ and kept at that temperature for 24 hours. Then, solid-liquid separation, repeated washing of the solid with deionized water and ethanol, and vacuum drying were performed. The solid was then sintered at 600℃ for 1 hour under a protective atmosphere to obtain Fe2O3@C.

[0097] 2. Dissolve the fluorinated amphiphilic polymer as shown in formula (Ⅰ) in tetrahydrofuran to prepare an amphiphilic polymer solution; mix TiO2@C, CuO@C, and Fe2O3@C in a molar ratio of 1:1:30 to form a metal powder; mix the 3% amphiphilic polymer solution and the metal powder in an ice bath at a liquid-solid ratio of 10 ml:1 mg to form a suspension; then keep it at 150°C for 3 h for hydrothermal reaction; after the reaction, allow it to stand and solidify, separate the solid and liquid, and dry the solid to obtain the catalyst precursor;

[0098] 3. The catalyst precursor was impregnated in a 7% (w / w) amphiphilic polymer solution for 10 seconds, dried and cured at 60°C, and the impregnation and low-temperature drying were repeated once. Then, the precursor was sintered at 400°C under a protective atmosphere for 1 hour to obtain a carbon-doped titanium-copper-iron composite oxide, which was used as a catalyst.

[0099] The treatment steps for the production wastewater of tert-butylbenzoic acid in this embodiment are the same as those in Example 1.

[0100] Example 4

[0101] The only difference between Example 4 and Example 1 is the pH value and the amount of hydrogen peroxide used in the treatment step of the wastewater from the production of tert-butylbenzoic acid. The other reaction conditions and steps are the same as in Example 1.

[0102] In this embodiment, step S2 is as follows: The catalyst prepared in this embodiment 1 is loaded into an air wet oxidation reactor, the pH of the production wastewater is adjusted to 5.5, and hydrogen peroxide is added at a volume ratio of 0.1%. After the two are mixed, they are fed into the air wet oxidation reactor for wet oxidation reaction. The reaction temperature is set to 200℃ and the pressure is set to 10 MPa. Specifically, air is introduced at a ratio of 20 L O2 / 1 L wastewater. After the reaction is completed for 30 minutes, the waste gas generated by the air wet oxidation reactor is discharged to enter the next stage. After venting, air is continuously introduced to circulate the wet oxidation reaction and exhaust gas. The total reaction time is 2 hours.

[0103] Example 5

[0104] The only difference between Example 5 and Example 1 is the pH value and the amount of hydrogen peroxide used in the treatment step of the wastewater from the production of tert-butylbenzoic acid. The other reaction conditions and steps are the same as in Example 1.

[0105] In this embodiment, step S2 is as follows: The catalyst prepared in this embodiment 1 is loaded into an air wet oxidation reactor, the pH of the production wastewater is adjusted to 6, and hydrogen peroxide is added at a volume ratio of 0.2%. After the two are mixed, they are fed into the air wet oxidation reactor for wet oxidation reaction. The reaction temperature is set to 200℃ and the pressure is set to 10 MPa. Specifically, air is introduced at a ratio of 20 L O2 / 1 L wastewater. After the reaction is completed for 30 minutes, the waste gas generated by the air wet oxidation reactor is discharged to enter the next stage. After venting, air is continuously introduced to circulate the wet oxidation reaction and exhaust gas. The total reaction time is 2 hours.

[0106] Example 6

[0107] The only difference between Example 6 and Example 1 is the reaction temperature and pressure of S2 in the treatment step of the wastewater from the production of tert-butylbenzoic acid. The other reaction conditions and steps are the same as in Example 1.

[0108] In this embodiment, step S2 is as follows: The catalyst prepared in this embodiment 1 is loaded into an air wet oxidation reactor, the pH of the production wastewater is adjusted to 5, and hydrogen peroxide is added at a volume ratio of 0.05%. After the two are mixed, they are fed into the air wet oxidation reactor for wet oxidation reaction. The reaction temperature is set to 160℃ and the pressure is 1 MPa. Specifically, air is introduced at a ratio of 20 L O2 / 1 L wastewater. After the reaction is completed for 30 minutes, the waste gas generated by the air wet oxidation reactor is discharged to enter the next stage. After venting, air is continuously introduced to circulate the wet oxidation reaction and exhaust gas. The total reaction time is 2 hours.

[0109] Example 7

[0110] The only difference between Example 7 and Example 1 is the reaction temperature and pressure of S2 in the treatment step of the wastewater from the production of tert-butylbenzoic acid. The other reaction conditions and steps are the same as in Example 1.

[0111] In this embodiment, step S2 is as follows: The catalyst prepared in this embodiment 1 is loaded into an air wet oxidation reactor, the pH of the production wastewater is adjusted to 5, and hydrogen peroxide is added at a volume ratio of 0.05%. After the two are mixed, they are fed into the air wet oxidation reactor for wet oxidation reaction. The reaction temperature is set to 180℃ and the pressure is 5 MPa. Specifically, air is introduced at a ratio of 20 L O2 / 1 L wastewater. After the reaction is completed for 30 minutes, the waste gas generated by the air wet oxidation reactor is discharged to enter the next stage. After venting, air is continuously introduced to circulate the wet oxidation reaction and exhaust gas. The total reaction time is 2 hours.

[0112] Comparative Example 1

[0113] The only difference between this comparative example and Example 1 is that TiO2@C is not added to the suspension during catalyst preparation, and the treatment steps for the production wastewater of tert-butylbenzoic acid are the same as in Example 1.

[0114] Comparative Example 2

[0115] The only difference between this comparative example and Example 1 is that CuO@C is not added to the suspension during catalyst preparation, and the treatment steps for the production wastewater of tert-butylbenzoic acid are the same as in Example 1.

[0116] Comparative Example 3

[0117] The only difference between this comparative example and Example 1 is that Fe2O3@C is not added to the suspension during catalyst preparation, while the treatment steps for the production wastewater of tert-butylbenzoic acid are the same as in Example 1.

[0118] Comparative Example 4

[0119] The only difference between this comparative example and Example 1 is that TiO2@C, CuO@C, and Fe2O3@C are used directly in the catalyst preparation process, without reacting with the amphiphilic polymer. The treatment steps for the production wastewater of tert-butylbenzoic acid are the same as in Example 1.

[0120] Comparative Example 5

[0121] The only difference between this comparative example and Example 1 is that the impregnation step 3 is omitted in the catalyst preparation. All other reactions and conditions are the same as in Example 1. Specifically, step 3 in the preparation of the catalyst in this comparative example 3 is as follows:

[0122] Carbon-doped titanium-copper-iron composite oxide was prepared by sintering the catalyst precursor at 500℃ for 1.5h under a protective atmosphere, and it was used as a catalyst.

[0123] The treatment steps for the production wastewater of p-tert-butylbenzoic acid in this comparative example are the same as those in Example 1.

[0124] Comparative Example 6

[0125] The only difference between this comparative example and Example 1 is that the wet oxidation reaction in the treatment step of the wastewater from the production of tert-butylbenzoic acid uses a one-time air introduction, rather than a batch air introduction.

[0126] Comparative Example 7

[0127] The only difference between this comparative example and Example 1 is that hydrogen peroxide is not added to the wet oxidation reaction in the treatment step of the wastewater from the production of tert-butylbenzoic acid.

[0128] Comparative Example 8

[0129] The only difference between this comparative example and Example 1 is that the pH of the wet oxidation reaction is adjusted to 8 in the treatment step of the wastewater from the production of p-tert-butylbenzoic acid.

[0130] Comparative Example 9

[0131] The only difference between this comparative example and Example 1 is that TiO2, CuO, and Fe2O3 were used directly in the catalyst preparation without carbon doping. The treatment steps for the production wastewater of tert-butylbenzoic acid are the same as in Example 1.

[0132] The water samples treated in Examples 1 to 7 and Comparative Examples 1 to 9 were measured, and the results are shown in Table 1.

[0133] Table 1

[0134]

[0135]

[0136] As shown in Table 1, after treating the production wastewater of p-tert-butylbenzoic acid in Examples 1 to 7 of this invention, the COD, ammonia nitrogen, and sulfate concentrations all meet the Class I discharge standard of the Integrated Wastewater Discharge Standard GB8978-96.

[0137] A comparison of Examples 1, 4 and 5 shows that as the amount of hydrogen peroxide increases, the efficiency of the wet oxidation reaction increases. However, when the amount of hydrogen peroxide increases to a certain extent, the increase in reaction efficiency slows down.

[0138] A comparison of Examples 1, 6 and 7 shows that as the temperature and pressure of the wet oxidation reaction increase, the efficiency of the wet oxidation reaction increases. However, when the amount of wet oxidation increases to a certain extent, the increase in reaction efficiency slows down or even decreases.

[0139] As can be seen from the comparison of Example 1 and Comparative Examples 1 to 3, the removal of any metal oxide in the metal oxides will reduce the efficiency of the wet oxidation reaction, resulting in a decrease in the pollution removal effect. This is because the three metal oxides have a synergistic catalytic effect, and the removal of any one of them will affect the degradation efficiency.

[0140] As can be seen from the comparison between Example 1 and Comparative Example 4, the metal oxides do not react with the amphiphilic compounds, resulting in a significant decrease in the efficiency of the wet oxidation reaction and a substantial reduction in the pollution removal effect. This is because the amphiphilic compounds have an aggregation effect on the metal oxides and increase the specific surface area of ​​the metal, thus increasing the reaction efficiency. In Comparative Example 4, the metal oxides were directly mixed and used as a catalyst, which greatly weakened its catalytic effect.

[0141] As can be seen from the comparison of Example 1 and Comparative Example 5, the wet oxidation reaction efficiency is reduced when the metal oxide reacts with the amphiphilic compound without impregnation treatment, resulting in a decrease in the pollution removal effect. This is because impregnation treatment promotes the formation of a membrane and a porous membrane structure, and omitting the impregnation treatment weakens the catalytic effect to some extent.

[0142] As can be seen from the comparison between Example 1 and Comparative Example 6, the use of a single-pass oxygen flow during the wet oxidation reaction reduces reaction efficiency and leads to a poorer pollution removal effect. The reason is that a single-pass oxygen flow results in the production of gases containing sulfides and nitrogen oxides during the reaction, which is not conducive to the forward advancement of the oxidation reaction and consumes oxygen.

[0143] As can be seen from the comparison between Example 1 and Comparative Example 7, the absence of hydrogen peroxide in the wet oxidation process reduces reaction efficiency, resulting in poorer pollution removal. Hydrogen peroxide enhances the oxidizing properties of air and acts as a "starter" for the reaction. Removing hydrogen peroxide weakens the oxidizing properties of the gas and slows down the wet oxidation process, thereby reducing the efficiency of pollutant degradation.

[0144] A comparison of Example 1 and Comparative Example 8 shows that adjusting the pH to a weakly alkaline state during the wet oxidation reaction reduces reaction efficiency, resulting in a significant decrease in pollution removal effectiveness. This indicates that an alkaline environment inhibits the catalytic effect. The acidic environment in Example 1 is beneficial for improving the catalytic activity in the wet oxidation reaction; however, as the pH continues to decrease and acidity increases, some metal oxidants become soluble. This not only hinders subsequent catalyst recovery, increasing post-treatment costs, but also leads to excessive levels of heavy metals in the wastewater.

[0145] As can be seen from the comparison between Example 1 and Comparative Example 9, the lack of carbon doping in metal oxides reduces reaction efficiency, resulting in poorer pollution removal. Carbon doping can promote the hydrophilicity of the catalyst, thereby facilitating the generation of catalytic free radicals.

[0146] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for treating wastewater from the production of p-tert-butylbenzoic acid, characterized in that, The processing method includes the following steps: The wastewater from the production of tert-butylbenzoic acid will be homogenized and adjusted. Adjust the pH of the production wastewater to 5-6, add an initiator, introduce oxygen-containing gas, and carry out a wet oxidation reaction at 160℃-200℃, 1MPa-10MPa and under continuous stirring. The waste gas generated by the wet oxidation reaction enters the desulfurization and denitrification reactor for purification treatment; The initiator comprises hydrogen peroxide and a catalyst, wherein the catalyst is a carbon-doped titanium-copper-iron composite oxide; the catalyst is prepared by: Carbon-doped metal oxides TiO2@C, CuO@C, and Fe2O3@C were prepared separately. The preparation steps were as follows: Citric acid and surfactant were mixed at a mass ratio of 5~15:1 and dissolved in water to obtain a carbon source solution; TiO2, CuO, and Fe2O3 powders were respectively immersed in the carbon source solution and heated to 150℃~170℃ for 10~30h; after the reaction, the solid and liquid were separated, and the precipitate obtained after repeated rinsing was vacuum dried; under a protective atmosphere, the dried solid was sintered at 500℃~700℃ for 1h~2h to obtain carbon-doped metal oxides. TiO2@C, CuO@C, and Fe2O3@C are mixed and then uniformly dispersed in an amphiphilic polymer solution with a mass concentration of 1% to 3% under ice bath conditions to form a suspension; the amphiphilic polymer solution is a solution formed by dissolving the amphiphilic polymer in an organic solvent; The suspension was subjected to hydrothermal reaction at 100℃~150℃ for 3h~6h, and after the reaction, it was allowed to stand and solidify, then the solid was separated and dried to obtain the catalyst precursor. The catalyst precursor was impregnated in a 5%–10% amphiphilic polymer solution for 5–20 seconds, dried and cured at a low temperature of 50°C–60°C, and the impregnation and low-temperature drying were repeated at least once. Then, the precursor was sintered at a high temperature of 400°C–600°C under a protective atmosphere for 1–2 hours to obtain carbon-doped titanium-copper-iron composite oxide.

2. The method for treating wastewater from the production of p-tert-butylbenzoic acid according to claim 1, characterized in that, The oxygen-containing gas is introduced in batches and intermittently. Specifically, after the oxygen-containing gas is introduced for wet oxidation reaction, the waste gas is discharged 15 to 30 minutes later. After the exhaust is completed, oxygen-containing gas is introduced again for wet oxidation reaction, and the operation is repeated.

3. The method for treating wastewater from the production of p-tert-butylbenzoic acid according to claim 1, characterized in that, The surfactant used is a quaternary ammonium salt surfactant.

4. The method for treating wastewater from the production of p-tert-butylbenzoic acid according to claim 1, characterized in that, The amphiphilic polymer is a fluorinated amphiphilic polymer; the organic solvent is tetrahydrofuran.

5. The method for treating wastewater from the production of p-tert-butylbenzoic acid according to claim 1, characterized in that, According to the molar ratio, the ratio of Ti:Cu:Fe in carbon-doped titanium-copper-iron composite oxides is 1:1:10~30.

6. The method for treating wastewater from the production of p-tert-butylbenzoic acid according to claim 1, characterized in that, The liquid-to-solid ratio for preparing the suspension is (5~10) mL:1g.

7. The method for treating wastewater from the production of p-tert-butylbenzoic acid according to claim 1, characterized in that, The waste gas generated by the wet oxidation reaction enters the desulfurization and denitrification reactor for purification treatment. The specific steps are as follows: The waste gas is fed into the desulfurization and denitrification reactor from the bottom, where it comes into countercurrent contact with the absorbent liquid sprayed down for primary purification. The solid absorption bed built into the upper part of the desulfurization and denitrification reactor performs secondary purification of the gas; The absorbent is a calcium or sodium salt solution; the packing material for the solid absorption bed is a molecular sieve or activated carbon.

8. The method for treating wastewater from the production of p-tert-butylbenzoic acid according to claim 1, characterized in that, The amount of hydrogen peroxide used is 0.05% to 0.2% of the wastewater volume.

9. The method for treating wastewater from the production of p-tert-butylbenzoic acid according to claim 1, characterized in that, The wet oxidation reaction time is 1h to 2h.

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