CN113387485B

CN113387485B - Method for treating para-ester production wastewater through complex extraction

Info

Publication number: CN113387485B
Application number: CN202110951017.5A
Authority: CN
Inventors: 杨峻; 程迪; 张天宇; 许传东; 张富全
Original assignee: Shenyang Huiyu Chemical Environmental Protection Technology Co ltd; Beijing Huiyu Lebang Environmental Protection Technology Co ltd
Current assignee: Shenyang Huiyu Chemical Environmental Protection Technology Co ltd; Beijing Huiyu Lebang Environmental Protection Technology Co ltd
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2021-11-16
Anticipated expiration: 2041-08-18
Also published as: CN113387485A

Abstract

The invention relates to a method for treating para-ester production wastewater by complexing extraction. The method for treating the para-ester production wastewater by complexing extraction comprises the following steps: firstly, carrying out oxidation treatment on para-ester production wastewater to obtain oxidation treatment liquid; the reaction temperature of the oxidation treatment is 150-250 ℃, and the pressure is 1-8 MPa; and then carrying out complexing extraction treatment on the oxidation treatment liquid, wherein an extracting agent adopted in the complexing extraction treatment comprises a complexing agent, and the complexing agent comprises one or more of N503, tributyl phosphate and N-lauryl (trialkyl methyl) amine. The invention can treat high-concentration para-ester wastewater, has high COD removal rate, and can also recover inorganic salt in the wastewater to reduce hazardous waste.

Description

Method for treating para-ester production wastewater through complex extraction

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to a method for treating para-ester production wastewater by complexing extraction.

Background

Para-ester, alternative name: para- (beta-ethyl sulfate sulfuryl) aniline belongs to a dye intermediate series, is one of main intermediates for producing reactive dyes, has large demand for more than 10 manufacturers at present in China, and is used for synthesizing EF-type, KN-type, M/KM-type, ME-type and other vinyl sulfuryl-containing reactive dyes.

Para-ester structure

Para-ester generates a large amount of high-concentration organic wastewater in the production process. The wastewater has complex components, high concentration, high salt content and high chromaticity. The waste water has biological toxicity and is difficult to be biochemically degraded. The characteristics of the waste water determine that the waste water can not be treated by the traditional methods such as simple materialization, biochemistry and the like, so the treatment difficulty is very high.

Patent document CN107758966A discloses a method for treating wastewater from para-ester production, which uses photocatalytic oxidation to treat wastewater to improve the biodegradability of wastewater, but this method can only treat relatively low concentration para-ester wastewater, and has low COD removal rate and limited treatment capacity.

Therefore, aiming at the characteristics of complexity, high concentration, high salt content, difficult biodegradation and the like of the para-ester wastewater, a method for effectively treating the para-ester production wastewater is required to be found, and the defects of the existing method are overcome so as to meet the requirements of industrial production and water treatment.

Disclosure of Invention

The invention aims to provide a method for treating para-ester production wastewater by complexing extraction, which can treat high-concentration para-ester wastewater, has high COD removal rate, can recover inorganic salts in the wastewater and realize hazardous waste reduction.

In order to achieve the above purpose, the invention provides the following technical scheme:

the method for treating the para-ester production wastewater by complexing extraction comprises the following steps:

firstly, carrying out oxidation treatment on para-ester production wastewater to obtain oxidation treatment liquid; the reaction temperature of the oxidation treatment is 150-250 ℃, and the pressure is 1-8 MPa;

and then carrying out complexing extraction treatment on the oxidation treatment liquid, wherein an extracting agent adopted in the complexing extraction treatment comprises a complexing agent, and the complexing agent comprises one or more of N503, tributyl phosphate and N-lauryl (trialkyl methyl) amine.

The invention decomposes macromolecular organic matters into polar organic matters through oxidation treatment, and deeply removes the polar organic matters through a complexing extraction technology, thereby solving the problem that macromolecular pollutants are difficult to eradicate, improving the removal rate of COD, and still having good removal effect even aiming at high-concentration wastewater.

In the invention, the oxidation reaction is usually influenced by the temperature and the pressure of a reaction system, when the oxidation reaction temperature is higher than 250 ℃, the reaction pressure is rapidly increased, the operation risk is increased, the equipment investment and the operation cost are greatly increased, when the temperature is lower than 150 ℃, organic matters contained in the para-ester production wastewater are difficult to decompose or the decomposition rate is relatively slow, and the removal rate of COD is not high. The reaction pressure is more than 8MPa, the increased pressure does not contribute much to the whole reaction, and the burden of a reaction container and a pipeline is increased; the pressure is less than 1MPa, the reaction is slow, and even no effect is produced.

In some embodiments, the oxidation treatment employs any gas having an oxidizing property, such as air or oxygen, as an oxidizing agent.

In some embodiments, the oxidation treatment is carried out at a reaction temperature of 200 to 250 ℃, such as 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃ and the like, and at a pressure of 3.5 to 6MPa, such as 3.5MPa, 4.0MPa, 4.5 MPa, 5.0MPa, 5.5 MPa, 6.0 MPa and the like. Under the temperature and the pressure, the oxidation reaction rate is faster and the reaction is more complete, the oxidation treatment effect of the pretreated wastewater is good, the requirement of the reaction condition on reaction equipment is not high, and the method can be carried out in the traditional oxidation reactor.

In some embodiments, the oxidation treatment is performed by a means for accelerating the reaction such as stirring, and the reaction time is preferably kept at 1 hour or more to promote sufficient degradation of the macromolecular organic substance.

In some embodiments, the extractant of the complex extraction process further comprises a co-solvent: 2-heptyl undecanol, sec-octanol and isohexadecyl alcohol. The cosolvent is helpful for the uniform dispersion of the complexing agent, and not only improves the utilization rate of the complexing agent, but also improves the reaction rate.

In some embodiments, the extractant of the complex extraction process further comprises a diluent: at least one of jet fuel or diesel fuel.

In some embodiments, the extractant of the complex extraction process comprises a complexing agent and a co-solvent, or a combination of a complexing agent, a co-solvent, and a diluent. In the combination, the ratio of the complexing agent to the cosolvent is 10-40% and 10-20% respectively (accounting for the total volume of the extractant), and the rest is optionally a diluent.

In some embodiments, the complexing extraction treatment is that the dosage of an extracting agent and the reaction pH have a significant influence on the complexing rate, preferably, the volume ratio of the extracting agent to the oxidation treatment solution is 10-40: 100, and the extraction reaction time is preferably 30-60 min. It is preferable to adjust the pH of the oxidation treatment liquid to 1 to 4, for example, pH =1, pH =2, pH =3, pH =4, or the like, before the complex extraction treatment.

In some embodiments, the complex extraction treatment further comprises: adding alkali liquor into the upper organic phase obtained by extraction for reaction, and recovering the extracting agent to realize the regeneration of the extracting agent.

And/or the presence of a gas in the gas,

evaporating and concentrating the lower aqueous phase obtained by extraction, and recovering salt.

The lye added during the recovery of the extractant may optionally be an inorganic base, for example a 10-20% sodium hydroxide solution. The regeneration process is carried out according to the following alkaline solution: the extraction organic phase =1:4-10 (volume ratio), and the reaction time for adding the alkali liquor is controlled to be 0.5-10 h.

Compared with the prior art, the invention achieves the following technical effects:

(1) the invention utilizes a method combining wet oxidation and complex extraction coupling technology to treat the production wastewater of para-ester, the production wastewater mainly adopts a typical method such as acetanilide method and the like to prepare the wastewater generated by para-ester, and the wastewater usually contains sulfamic acid, sodium sulfite and unreacted raw materials such as acetanilide, thionyl chloride and other impurities. The invention firstly decomposes macromolecular organic matters into polar organic matters, and then deeply removes the polar organic matters by the complexing extraction technology, solves the problem that macromolecular pollutants are difficult to eradicate, not only achieves good effect on wastewater treatment, but also can recover inorganic salts in wastewater, realizes hazardous waste reduction, and has stable removal effect and obvious economic benefit.

(2) The COD removal rate of the wastewater treated by the method is about 90 percent (the removal rate before salt is recovered by evaporation and concentration), the biodegradability of the distilled water is improved, the stability of the subsequent biochemical treatment effect can be ensured, and the chroma removal rate is more than 90 percent.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a flow chart of the method for treating para-ester wastewater by complexation and extraction.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The raw materials, reagents or instruments used are not indicated by manufacturers, and all the raw materials, the reagents or the instruments are conventional products which can be obtained by commercial purchase or can be prepared according to the prior art.

The following examples refer primarily to the process shown in FIG. 1 for treating wastewater.

Example 1

The wastewater used in the embodiment is obtained from para-ester production wastewater of a chemical plant in Zhejiang, and the water quality conditions are as follows: pH =8, COD =59270mg/L, salt content 15%, brown-yellow.

Step 1, wet oxidation: transferring the para-ester production wastewater into an oxidation reactor, introducing air, heating to 200 ℃, adjusting the pressure of the oxidation reactor to be 3.5MPa, stirring at 320r/min, continuously reacting for 2.5h to obtain an oxidation treatment liquid, and performing wet oxidation treatment to obtain a COD removal rate of 70-75%.

Step 2, complex extraction: preparation of a complexing extraction agent: respectively and uniformly mixing 350mL of LN503, 150mL of isohexanol and 500mL of aviation kerosene to prepare a complexing extraction agent; and (3) complexing extraction treatment: taking 400mL of oxidized effluent, adjusting the pH to be 2-3, adding 100mL of complex extracting agent, reacting for 45 minutes, standing and layering to obtain an extract phase and a water phase, carrying out regeneration reaction on the extract phase, and analyzing a sample of the water phase;

specifically, after wet oxidation, the polar pollutants in the wastewater are mixed with the extractant and then undergo a complex reaction to form a water-insoluble macromolecular complex which is dissolved in the upper extraction phase, so that the separation from the wastewater is realized. After the complexing extraction treatment step, the removal rate of COD is 60-70%.

Regeneration of an extracting agent: and (3) carrying out regeneration reaction on the extraction phase and a sodium hydroxide solution with the mass fraction of 18% according to the volume ratio of 7:1, reacting for 45 minutes, and standing for layering. The upper layer is a regenerated extracting agent which can be reused for next wastewater treatment; the lower layer is a concentrated liquid phase.

Specifically, during the regeneration of the extractant, the macromolecular complex in the extraction phase reacts with the base to form a water-soluble salt which is dissolved in the aqueous base phase.

After analysis, the pretreated effluent water after complexation extraction has COD: 5853mg/L, removal rate 90%, the treated water is nearly colorless. After evaporation and concentration, water COD is evaporated: 451mg/L, the removal rate is 99 percent, the salt recovered by evaporation is white, and each index of the effluent can reach the third grade of the Integrated wastewater discharge Standard (GB 8978-96).

Example 2

The wastewater used in this example was the same as in example 1, and the following was carried out:

step 1, wet oxidation: transferring the para-ester production wastewater into an oxidation reactor, introducing air, heating to 220 ℃, adjusting the pressure of the oxidation reactor to 4.8MPa, stirring at 400r/min, and continuously reacting for 2 hours to obtain an oxidation treatment solution.

Step 2, preparation of a complex extractant: respectively and uniformly mixing 400mL of lauryl (trialkyl methyl) amine, 100mL of sec-octylalcohol and 500mL of aviation kerosene to prepare a complexing extraction agent;

performing complex extraction reaction: taking 300mL of oxidized effluent, adjusting the pH to be 1.5-2, adding 100mL of complex extracting agent, mixing and transferring mass for 30 minutes, standing and layering to obtain an extraction phase and a water phase, carrying out regeneration reaction on the extraction phase, and sampling and analyzing the water phase;

regeneration of an extracting agent: and (3) carrying out regeneration reaction on the extraction phase and a sodium hydroxide solution with the mass fraction of 12% according to the volume ratio of 3:1, reacting for 35 minutes, and standing for layering. The upper layer is a regenerated extracting agent which can be reused for next wastewater treatment; the lower layer is a concentrated liquid phase.

After analysis, the pretreated wastewater after complexation extraction has the following Chemical Oxygen Demand (COD): 4382mg/L, the removal rate is 92.6 percent. After evaporation and concentration, water COD is evaporated: 315mg/L, the removal rate is 99 percent, the evaporated and recovered salt is white, and each index of the effluent can reach the third grade of the Integrated wastewater discharge Standard (GB 8978-96).

Example 3

The wastewater used in this example was obtained from the wastewater from the para-ester production of a chemical plant in Hubei, and the water quality was as follows: pH =7-8, COD =83527mg/L, salt content 13%, brown-yellow.

Step 1, wet oxidation: transferring the para-ester production wastewater into an oxidation reactor, introducing air, heating to 250 ℃, adjusting the pressure of the oxidation reactor to 5.0MPa, stirring at the speed of 300r/min, and continuously reacting for 2 hours to obtain an oxidation treatment solution.

Step 2, preparation of a complex extractant: respectively and uniformly mixing 350mL of lauryl (trialkyl methyl) amine, 50mL of tributyl phosphate, 150mL of isohexanol and 450mL of aviation kerosene to prepare a complex extracting agent;

performing complex extraction reaction: taking 500mL of oxidized effluent, adjusting the pH to be 1.5-2, adding 200mL of complex extracting agent, reacting for 25 minutes, standing and layering to obtain an extraction phase and a water phase, carrying out regeneration reaction on the extraction phase, and sampling and analyzing the water phase;

regeneration of an extracting agent: carrying out regeneration reaction on the extraction phase and a sodium hydroxide solution with the mass fraction of 25% according to the volume ratio of 8:1, reacting for 30 minutes, and standing for layering. The upper layer is a regenerated extracting agent which can be reused for next wastewater treatment; the lower layer is a concentrated liquid phase.

After analysis, the pretreated wastewater after complexation extraction has the following Chemical Oxygen Demand (COD): 7136mg/L, the removal rate is 91.4%. After evaporation and concentration, water COD is evaporated: 438mg/L, removal rate 99%, evaporation recovery of salt white.

Example 4

The wastewater used in this example was obtained from the wastewater from the para-ester production of a chemical plant in Henan, and the water quality was as follows: pH =5-6, COD =33184mg/L, salt content 7%, yellow.

Step 1, wet oxidation: transferring the para-ester production wastewater into an oxidation reactor, introducing air, heating to 200 ℃, adjusting the pressure of the oxidation reactor to 3.8MPa, stirring at 300r/min, and continuously reacting for 1.5h to obtain an oxidation treatment solution.

Step 2, preparation of a complex extractant: respectively and uniformly mixing 300mL of LN503, 50mL of tributyl phosphate, 150mL of 2-heptyl undecanol and 500mL of diesel oil to prepare a complexing extractant;

performing complex extraction reaction: taking 500mL of oxidized effluent, adjusting the pH to be 2-4, adding 250mL of complex extracting agent, reacting for 45 minutes, standing and layering to obtain an extraction phase and a water phase, carrying out regeneration reaction on the extraction phase, and sampling and analyzing the water phase;

regeneration of an extracting agent: and (3) carrying out regeneration reaction on the extraction phase and a sodium hydroxide solution with the mass fraction of 20% according to the volume ratio of 5:1, reacting for 45 minutes, and standing for layering. The upper layer is a regenerated extracting agent which can be reused for next wastewater treatment; the lower layer is a concentrated liquid phase.

After analysis, the pretreated wastewater after complexation extraction has the following Chemical Oxygen Demand (COD): 3836mg/L, the removal rate is 88.4 percent. After evaporation and concentration, water COD is evaporated: 211mg/L, removal rate 99%, evaporation recovery of salt white.

Example 5

The wastewater used in example 3 was obtained by the following method:

step 1, wet oxidation: transferring the para-ester production wastewater into an oxidation reactor, introducing air, heating to 250 ℃, adjusting the pressure of the oxidation reactor to 5.8MPa, stirring at 350r/min, and continuously reacting for 1.5h to obtain an oxidation treatment solution.

Step 2, preparation of a complex extractant: respectively and uniformly mixing 350mL of LN503, 100mL of 2-heptyl undecanol and 550mL of diesel oil to prepare a complexing extractant;

performing complex extraction reaction: taking 400mL of oxidized effluent, adjusting the pH to be 1-2, adding 200mL of complex extracting agent, reacting for 30 minutes, standing and layering to obtain an extract phase and a water phase, carrying out regeneration reaction on the extract phase, and sampling and analyzing the water phase;

regeneration of an extracting agent: and (3) carrying out regeneration reaction on the extraction phase and a sodium hydroxide solution with the mass fraction of 15% according to the volume ratio of 5:1, reacting for 30 minutes, and standing for layering. The upper layer is a regenerated extracting agent which can be reused for next wastewater treatment; the lower layer is a concentrated liquid phase.

After analysis, the pretreated wastewater after complexation extraction has the following Chemical Oxygen Demand (COD): 5383mg/L, and the removal rate is 93.5%. After evaporation and concentration, water COD is evaporated: 387mg/L, removal 99% and evaporation recovery of the salt as white. The indexes of the effluent can reach the third grade of Integrated wastewater discharge Standard (GB 8978-96).

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. The method for treating para-ester production wastewater by complexing extraction is characterized in that the para-ester production wastewater is wastewater generated by preparing para-ester by adopting an acetanilide method, and comprises the following steps:

firstly, carrying out oxidation treatment on para-ester production wastewater to obtain oxidation treatment liquid; the oxidation treatment adopts air or oxygen as an oxidant; the reaction temperature of the oxidation treatment is 200-250 ℃, and the pressure is 3.5-6 MPa;

then carrying out complexing extraction treatment on the oxidation treatment liquid, wherein an extracting agent adopted in the complexing extraction treatment comprises a complexing agent, a cosolvent and a diluent, and the complexing agent comprises one or more of N503, tributyl phosphate and N-lauryl (trialkyl methyl) amine; the cosolvent is at least one of 2-heptyl undecanol, sec-octanol and isohexanol; the diluent is at least one of aviation kerosene or diesel oil; in the extractant, the complexing agent and the cosolvent respectively account for 10-40% and 10-20% by volume ratio.

2. The method of claim 1, wherein the pH of the oxidation treatment fluid is adjusted to 1-4 prior to the complex extraction treatment.

3. The method according to claim 1, wherein the volume ratio of the extraction agent to the oxidation treatment solution is 10-40: 100, and the extraction reaction time is 30-60 min.

4. The method of claim 1, further comprising, after the complex extraction treatment: adding alkali liquor into the upper organic phase obtained by extraction to react, and recovering the extracting agent;

and/or the presence of a gas in the gas,