Method for recycling and treating wastewater from the production of 2,5-diaminotoluene sulfate

Abstract

The present application belongs to the field of fine chemical wastewater treatment technology, and is specifically related to a kind of recycling treatment method of 2,5-diaminotoluene sulfate production wastewater.The recycling treatment method of the present application includes the pH adjustment of 2,5-diaminotoluene sulfate production wastewater to neutrality, adds separating agent, and stratification after reaction obtains the lower layer as the first aqueous phase, and the upper layer is separated phase;The first aqueous phase goes to evaporate and desalinate, and acidic solution is added to separated phase, and stratification after reaction obtains the lower layer as recovery phase, and the upper layer is separating agent regeneration phase, and separating agent regeneration phase is used for circulating 2,5-diaminotoluene sulfate production wastewater, and alkaline solution or sulfate solution are added in recovery phase to recover o-toluidine or 2,5-diaminotoluene sulfate.The processing method of the present application is simple to operate, and has certain economic benefits.

Description

Technical Field

[0001] The present application belongs to the technical field of fine chemical wastewater treatment, and specifically relates to a method for recycling and treating 2,5-diaminotoluene sulfate production wastewater. Background Art

[0002] 2,5-Diaminotoluene sulfate belongs to the 2,5-diaminotoluene series of products. It is widely used as a precursor of the high-end hair dye component, that is, the coupling component. It is now the main ingredient for popular dyeing in high-end hair cosmetics, replacing p-phenylenediamine. It also has important uses in the fields of medicine and polymer materials. Its structural formula is as follows:

[0003]

[0004] The industrial synthesis of 2,5-diaminotoluene sulfate usually adopts the following method: using o-toluidine as raw material, 2,5-diaminotoluene is prepared through diazotization-coupling reaction and catalytic hydrogenation reaction, and the product is subjected to post-treatment salt formation reaction to finally obtain 2,5-diaminotoluene sulfate.

[0005] The production process of 2,5-diaminotoluene sulfate typically generates wastewater from different pathways: heavy chemical wastewater and reduced chemical wastewater. The reduced chemical wastewater contains a certain concentration of 2,5-diaminotoluene sulfate, while the heavy chemical wastewater contains the carcinogen o-toluidine. These wastewaters exhibit dark color, high levels of toxic organic pollutants, and are not readily biodegradable, making them difficult to treat using traditional simple physical, chemical, or biochemical methods. Currently, Fenton oxidation or adsorption methods are typically used to treat this type of wastewater. However, both methods require high treatment dosages and generate large amounts of solid sludge or waste that are difficult to recycle. Summary of the Invention

[0006] The technical purpose of the present application is to at least solve the problems of the existing method for treating wastewater from the production of 2,5-diaminotoluene sulfate, such as the large amount of treatment agent used and the generation of a large amount of solid sludge or waste that is difficult to recycle.

[0007] This purpose is achieved through the following technical solutions:

[0008] In a first aspect, the present application provides a method for recycling and treating 2,5-diaminotoluene sulfate production wastewater, comprising:

[0009] The pH of the wastewater produced by 2,5-diaminotoluene sulfate is adjusted to neutral, a separating agent is added, and after the reaction, the wastewater is allowed to stand for separation to obtain a lower layer as the first aqueous phase and an upper layer as the separated phase;

[0010] An acidic solution is added to the separated phase, and after the reaction, the mixture is allowed to stand for separation to obtain a lower layer as a recovery phase and an upper layer as a separation agent regeneration phase, wherein the separation agent regeneration phase is used for cyclic treatment of 2,5-diaminotoluene sulfate production wastewater;

[0011] The processing method of the recovered phase includes any one of the following:

[0012] (1) adding an alkaline solution to the recovery phase to recover o-toluidine;

[0013] (2) adding a sulfate solution to the recovery phase to recover 2,5-diaminotoluene sulfate;

[0014] (3) adding an alkaline solution to the recovery phase to recover o-toluidine, and then adding a sulfate solution to recover 2,5-diaminotoluene sulfate.

[0015] In some embodiments of the present application, in method (1),

[0016] An alkaline solution is added to the recovered phase to adjust the pH to 6.5-7.5. After the reaction, the phase is allowed to stand for separation to obtain a lower layer as the second aqueous phase and an upper layer as the recovered o-toluidine.

[0017] In some embodiments of the present application, in method (1), the reaction is a room temperature reaction;

[0018] The first aqueous phase and the second aqueous phase are subjected to evaporation and desalination treatment.

[0019] In some embodiments of the present application, in method (2),

[0020] Adding an alkaline solution to the recovered phase to adjust the pH to 6.5-7.5, filtering after the reaction, adjusting the pH of the filtrate to 1.5-2.5, adding a sulfate solution, cooling at low temperature, and precipitating 2,5-diaminotoluene sulfate;

[0021] The low-temperature cooling temperature is 0-10°C.

[0022] In some embodiments of the present application, in method (3),

[0023] An alkaline solution is added to the recovered phase to adjust the pH to 6.5-7.5. After the reaction, the phase is allowed to stand for separation to obtain an upper layer as the recovered o-toluidine and a lower layer as the third aqueous phase. The third aqueous phase is filtered, and the pH of the filtrate is adjusted to 1.5-2.5. A sulfate solution is then added, and the phase is cooled at low temperature to precipitate 2,5-diaminotoluene sulfate.

[0024] The low-temperature cooling temperature is 0-10°C.

[0025] In some embodiments of the present application, the alkaline solution comprises any one of sodium hydroxide, potassium hydroxide, and ammonia water;

[0026] The sulfate solution comprises an aqueous solution of any one of sodium sulfate and potassium sulfate;

[0027] Preferably, the sulfate solution is a saturated solution at normal temperature and pressure.

[0028] In some embodiments of the present application, the acidic solution reacts with the separated phase in a water bath at 40 to 50° C.;

[0029] The volume ratio of the acidic solution to the separated phase is 1:(5-10);

[0030] The mass fraction of the acidic solution is 10% to 20%;

[0031] Preferably, the acidic solution is a hydrochloric acid solution or a sulfuric acid solution.

[0032] In some embodiments of the present application, the volume of the separating agent accounts for 5% to 30% of the volume of the 2,5-diaminotoluene sulfate production wastewater.

[0033] In some embodiments of the present application, the separating agent comprises the following components in volume percentages:

[0034] Complexing agent: 10% to 40%;

[0035] Cosolvent: 10% to 20%;

[0036] The remainder is diluent.

[0037] In some embodiments of the present application, the complexing agent comprises one or a combination of two or more of cyclohexane acid, 2-ethylhexyl phosphoric acid, or 5,8-dinonyl-2-naphthalenesulfonic acid;

[0038] The cosolvent is an isomeric alcohol with a carbon chain of 8 to 20;

[0039] The diluent comprises one or both of aviation kerosene and diesel.

[0040] Beneficial effects:

[0041] 1. The treatment method disclosed in this application can recycle o-toluidine and 2,5-diaminotoluene sulfate, has certain economic benefits, and the treatment process is simple, with high COD and chroma removal rates in wastewater.

[0042] 2. The treatment method disclosed in this application uses complex extraction + extractant regeneration to treat the production wastewater of 2,5-diaminotoluene sulfate, solving the problem of difficult removal of special pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to denote the same components. In the drawings:

[0044] Figure 1 The flowchart of the recycling method according to the embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0045] In the prior art, the industrial synthesis of 2,5-diaminotoluene sulfate generally adopts the following method: using o-toluidine as a raw material, preparing 2,5-diaminotoluene through a diazotization-coupling reaction and a catalytic hydrogenation reaction, and the product undergoes a post-treatment salt-forming reaction to finally obtain 2,5-diaminotoluene sulfate.

[0046] The production process of 2,5-diaminotoluene sulfate (2,5-DAT) typically generates wastewater from different pathways: heavy chemical wastewater and reduced chemical wastewater. The reduced chemical wastewater contains a certain concentration of 2,5-DAT (e.g., 2-4 kg per ton of reduced chemical wastewater), and the heavy chemical wastewater contains the carcinogen o-toluidine (e.g., 2-5 kg ​​per ton of heavy chemical wastewater). These wastewaters exhibit dark color, high levels of toxic organic pollutants, and are not readily biodegradable, making them difficult to treat using traditional simple physical, chemical, or biochemical methods. Currently, these wastewaters are typically treated using Fenton oxidation or adsorption methods. However, both require high treatment doses and produce large amounts of difficult-to-recycle solid sludge or waste. Therefore, from an economic perspective, existing wastewater treatment methods are not suitable for wastewater generated by 2,5-DAT production.

[0047] Therefore, from the perspective of wastewater resource treatment and recycling, the present application proposes a treatment method for heavy chemical wastewater and reduction wastewater generated in the production process of 2,5-diaminotoluene sulfate. The treatment method is simple to operate and has certain economic benefits. For example, the current operating treatment cost per ton of wastewater is 50 to 60 yuan, and the economic benefits generated by o-toluidine and 2,5-diaminotoluene sulfate obtained per ton of wastewater treatment are about 60 to 70 yuan. The operating treatment cost can be further reduced by improving the treatment method in the future. In addition, the extractant of the present application is regenerable, and the COD of the first aqueous phase and the second aqueous phase obtained by treatment is low, the color is light, and it has good biodegradability. After combined with the currently mature biochemical system treatment, the water or recovered salt has high recycling value.

[0048] To achieve the above technical objectives, the present application discloses a method for recycling and treating 2,5-diaminotoluene sulfate production wastewater, comprising:

[0049] The pH of 2,5-diaminotoluene sulfate production wastewater is adjusted to neutral, a separating agent is added, and after the reaction, the mixture is allowed to stand for separation to obtain a lower layer as a first aqueous phase and an upper layer as a separation phase; an acidic solution is added to the separation phase, and after the reaction, the mixture is allowed to stand for separation to obtain a lower layer as a recovery phase and an upper layer as a separating agent regeneration phase, and the separating agent regeneration phase is used for circulating treatment of the 2,5-diaminotoluene sulfate production wastewater;

[0050] The treatment methods for the recovered phase include any of the following:

[0051] (1) adding an alkaline solution to the recovery phase to recover o-toluidine;

[0052] (2) adding a sulfate solution to the recovery phase to recover 2,5-diaminotoluene sulfate;

[0053] (3) adding an alkaline solution to the recovery phase to recover o-toluidine, and then adding a sulfate solution to recover 2,5-diaminotoluene sulfate.

[0054] The above method (1) is for heavy chemical wastewater, method (2) is for reducing wastewater, and method (3) is for wastewater containing both heavy chemical wastewater and reducing wastewater. Among them, the first aqueous phase contains salts, such as sulfate, etc., and evaporation and desalination treatment is adopted for recycling.

[0055] In some embodiments, in method (1), an alkaline solution is added to the recovered phase to adjust the pH to 6.5-7.5, and after the reaction, the phase is allowed to stand for separation to obtain a lower layer as the second aqueous phase and an upper layer as the recovered o-toluidine.

[0056] The alkaline solution herein includes an alkaline aqueous solution. This application primarily employs, but is not limited to, any aqueous solution of sodium hydroxide, potassium hydroxide, or ammonia. The pH may be adjusted to any specific value or range between 6.5 and 7.5. The second aqueous phase contains salts, such as chloride, which are then evaporated and desalinated for recycling.

[0057] In some embodiments, the reaction in method (1) is a room temperature reaction, and the reaction time includes any time that allows for a sufficient and complete reaction.

[0058] In some embodiments, in method (2), an alkaline solution is added to the recovery phase to adjust the pH to 6.5-7.5, the reaction is completed, the filtrate is filtered, the pH of the filtrate is adjusted to 1.5-2.5, and then a sulfate solution is added, and the mixture is cooled at low temperature to precipitate 2,5-diaminotoluene sulfate; wherein the low temperature cooling temperature is 0-10°C.

[0059] Specifically, the alkaline solution includes an alkaline aqueous solution. This application mainly uses any aqueous solution of sodium hydroxide, potassium hydroxide, and ammonia, but is not limited thereto. The pH can be adjusted to any specific value or range between 6.5 and 7.5. The filtration method includes any method conventional in the art, such as suction filtration. The method for adjusting the pH value of the filtrate includes adding an acidic solution, such as sulfuric acid or hydrochloric acid. This application preferably adds sulfuric acid. The concentration or amount of the acidic solution added includes any method conventional in the art until the pH of the filtrate reaches any specific value or range between 1.5 and 2.5. The sulfate solution includes any aqueous sulfate solution conventional in the art, such as any aqueous solution of sodium sulfate or potassium sulfate. To facilitate the precipitation of 2,5-diaminotoluene sulfate, this application chooses to use a saturated solution of sodium sulfate at room temperature and pressure. The low-temperature cooling method includes any cooling method conventional in the art, such as low-temperature cooling of hydrazine, etc. The low-temperature cooling temperature is controlled to any temperature between 0 and 10°C and is cooled until the amount of 2,5-diaminotoluene sulfate no longer increases.

[0060] In some embodiments, in method (3), an alkaline solution is added to the recovered phase to adjust the pH to 6.5-7.5. After the reaction, the phase is allowed to stand for separation to obtain an upper layer of recovered o-toluidine and a lower layer of a third aqueous phase. The third aqueous phase is filtered, and the pH of the filtrate is adjusted to 1.5-2.5. A sulfate solution is then added, and the phase is cooled at low temperature to precipitate 2,5-diaminotoluene sulfate; the cooling temperature is 0-10°C. The specific operation of method (3) is a combination of method (1) and method (2).

[0061] In some embodiments, during the reverse phase extraction process, the acidic solution reacts with the separated phase in a water bath at 40-50° C.; wherein the water bath comprises a conventional method in the art, and the water bath temperature comprises any temperature within a range of values.

[0062] In some embodiments, the volume ratio of the acidic solution to the separation phase is 1:(5-10). Too much or too little acidic solution is detrimental to the separation and extraction.

[0063] In some embodiments, the mass fraction of the acidic solution is 10% to 20%. The concentration and amount of the acidic solution are interrelated and are used to achieve a relatively ideal separation and extraction effect. The acidic solution here is a hydrochloric acid solution or a sulfuric acid solution.

[0064] In some embodiments, during the separation and extraction process, the volume of the separation agent accounts for 5% to 30% of the volume of the 2,5-diaminotoluene sulfate production wastewater.

[0065] In some embodiments, the separating agent comprises the following components in the following volume percentages: a complexing agent: 10% to 40%; a cosolvent: 10% to 20%; and the rest is a diluent, wherein the complexing agent comprises one or a combination of two or more of cyclohexane acid, 2-ethylhexyl phosphoric acid, or 5,8-dinonyl-2-naphthalenesulfonic acid; the cosolvent is an isomeric alcohol with a carbon chain of 8 to 20, such as one or a combination of two or more of isomeric octanol, isomeric decanol, and isomeric hexadecanol; and the diluent comprises one or both of aviation kerosene and diesel.

[0066] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0067] The chemical substances, reagents, etc. used in the following examples are all of any conventional models and manufacturers in the art.

[0068] The meanings and standards of the detection indicators in the following embodiments are as follows:

[0069] COD: Chemical oxygen demand, the detection method is the dichromate method, and the detection standard is HJ828-2017.

[0070] Chroma: The color of water. The detection method is the dilution multiple method and the detection standard is HJ1182-2021.

[0071] Salt content (TDS): Total dissolved solids. The detection method is TDS meter or weighing method. The detection standard is GB / T5750.4-2006 8.1.

[0072] Example 1

[0073] Disclosed is a method for recycling and treating 2,5-diaminotoluene sulfate production wastewater. The wastewater is heavy chemical wastewater generated during the production process of a chemical plant in Jiangsu Province. The heavy chemical wastewater contains about 0.3% by mass of o-toluidine. The water quality is as follows: purple-black color, pH = 6, COD = 34628 mg / L, chroma of 16000 times, and salt content (TDS) of 4%.

[0074] Take 2000mL of the above wastewater sample according to Figure 1 The process flow is as follows:

[0075] S1, prepare the separating agent: take 100 mL of cyclohexane acid, 300 mL of 2-ethylhexyl phosphoric acid, 200 mL of isomeric alcohol and 400 mL of aviation kerosene and mix them to obtain 1000 mL of separating agent;

[0076] S2, complex extraction: add 400 mL of the separating agent of S1 to 2000 mL of the above wastewater sample, mix thoroughly and react at room temperature for 25 to 40 minutes, let it stand to separate into layers, the upper layer is the separated phase, the lower layer is the first aqueous phase, and the first aqueous phase is evaporated and desalted; wherein, the reaction time of complex extraction includes the time for complete reaction.

[0077] S3, extractant regeneration: add a 12% by mass hydrochloric acid solution to the separated phase, wherein the volume ratio of the separated phase to the hydrochloric acid solution is 8:1, and fully react in a 45°C water bath for about 20 minutes. Let it stand and separate to obtain a lower layer as a recovery phase and an upper layer as a separating agent regeneration phase. The separating agent regeneration phase is used for the recycling treatment of 2,5-diaminotoluene sulfate production wastewater; wherein the reaction time for extractant regeneration includes the time for the full reaction to be complete.

[0078] S4, treating the recovered phase: adding 32% by mass of liquid alkali to the recovered phase. The liquid alkali here can be a conventional sodium hydroxide solution or other alkaline solution. The pH of the solution is adjusted to 7. After sufficient reaction for 30 minutes, the solution is allowed to stand and separate into layers. The lower layer is the second aqueous phase, and the upper layer is the recovered o-toluidine. The second aqueous phase is subjected to evaporation and desalination treatment. The calculated recovery rate is 66.7%.

[0079] Since the pH value of the heavy chemical wastewater is close to neutral, the present application uses direct complexation extraction in S2. For wastewater with a pH value not meeting the range of 6 to 8, conventional adjustment methods in the art can be used for adjustment.

[0080] In S3, the acidic solution can also be a sulfuric acid solution. Whether it is a sulfuric acid solution or a hydrochloric acid solution, the concentration used is 10-20% by mass. If it is lower than 10%, the amount of acidic solution added is large. If it is higher than 20%, the concentration is too high, which not only easily causes unnecessary side reactions, but also may be detrimental to subsequent processes. The selection of an appropriate concentration of the acidic solution is related to its usage. Specifically, the concentration of the acidic solution is 10-20%, and the volume ratio of the acidic solution to the separation phase satisfies 1:(5-10).

[0081] Table 1 List of recycling and treatment conditions

[0082]

[0083] Example 1-1

[0084] Disclosed is a method for recovering o-toluidine from 2,5-diaminotoluene sulfate production wastewater, which differs from Example 1 in that:

[0085] In S1, 50 mL of cyclohexane acid, 50 mL of 5,8-dinonyl-2-naphthalenesulfonic acid, 100 mL of isomeric alcohol and 800 mL of aviation kerosene were mixed to obtain 1000 mL of separating agent;

[0086] In S2, 100 mL of the separation agent from S1 was added to 2000 mL of the above wastewater sample;

[0087] In S3, the water bath reaction temperature was 40°C.

[0088] Recover o-toluidine, the calculated recovery rate is 66.7%

[0089] Table 2 Recycling and treatment status list

[0090]

[0091]

[0092] Example 1-2

[0093] Disclosed is a method for recovering o-toluidine from 2,5-diaminotoluene sulfate production wastewater, which differs from Example 1 in that:

[0094] In S1, 50 mL of cyclohexane acid, 70 mL of 5,8-dinonyl-2-naphthalenesulfonic acid, 80 mL of 2-ethylhexyl phosphoric acid, 150 mL of isomeric alcohol and 650 mL of diesel were mixed to obtain 1000 mL of separating agent;

[0095] In S2, 600 mL of the separation agent from S1 was added to 2000 mL of the above wastewater sample;

[0096] In S3, the water bath reaction temperature was 50°C.

[0097] o-Toluidine was recovered, and the recovery rate was calculated to be 83.3%.

[0098] Table 3 Recycling and treatment status list

[0099]

[0100] Examples 1-3

[0101] Disclosed is a method for recycling and treating 2,5-diaminotoluene sulfate production wastewater. The wastewater is heavy chemical wastewater generated during the production process of a chemical plant in Ningxia. The heavy chemical wastewater contains about 0.4% by mass of o-toluidine. The water quality is as follows: purple-black color, pH = 8, COD = 42060 mg / L, chroma of 20000 times, and salt content (TDS) of 4%.

[0102] Take 2000mL of the above wastewater sample according to Figure 1 The process flow is as follows:

[0103] S1, prepare the separating agent: take 50 mL of cyclohexane acid, 70 mL of 5,8-dinonyl-2-naphthalenesulfonic acid, 80 mL of 2-ethylhexyl phosphoric acid, 150 mL of isomeric alcohol and 650 mL of diesel to mix to obtain 1000 mL of separating agent;

[0104] S2, complex extraction: add 400 mL of the separating agent of S1 to 2000 mL of the above wastewater sample, mix thoroughly and react at room temperature for 25 to 40 minutes, let it stand to separate into layers, the upper layer is the separation phase, and the lower layer is the first aqueous phase. After extracting water from the first aqueous phase, it is concentrated and crystallized into salt; wherein, the reaction time of the complex extraction includes the time for the reaction to be complete.

[0105] S3, extractant regeneration: add a 12% by mass hydrochloric acid solution to the separated phase, wherein the volume ratio of the separated phase to the hydrochloric acid solution is 8:1, and fully react in a 45°C water bath for about 20 minutes. Let it stand and separate to obtain a lower layer as a recovery phase and an upper layer as a separating agent regeneration phase. The separating agent regeneration phase is used for the recycling treatment of 2,5-diaminotoluene sulfate production wastewater; wherein the reaction time for extractant regeneration includes the time for the full reaction to be complete.

[0106] S4, treating the recovery phase: adding 32% by mass of liquid caustic soda to the recovery phase, adjusting the solution pH to 7, and allowing the solution to react for 30 minutes. The solution was then allowed to stand and separate into layers, the lower layer being the second aqueous phase, and the upper layer being the recovered o-toluidine. The second aqueous phase was subjected to evaporation and desalination treatment to recover the o-toluidine, and the calculated recovery rate was 75%.

[0107] Since the pH value of the heavy chemical wastewater is close to neutral, the present application uses direct complexation extraction in S2. For wastewater with a pH value not meeting the range of 6 to 8, conventional adjustment methods in the art can be used for adjustment.

[0108] In S3, the acidic solution can also be a sulfuric acid solution. Whether it is a sulfuric acid solution or a hydrochloric acid solution, the concentration used is 10-20% by mass. If it is lower than 10%, the amount of acidic solution added is large. If it is higher than 20%, the concentration is too high, which not only easily causes unnecessary side reactions, but also may be detrimental to subsequent processes. The selection of an appropriate concentration of the acidic solution is related to its usage. Specifically, the concentration of the acidic solution is 10-20%, and the volume ratio of the acidic solution to the separation phase satisfies 1:(5-10).

[0109] Table 4 Recycling and treatment status list

[0110]

[0111] Example 2

[0112] Disclosed is a method for recycling and treating 2,5-diaminotoluene sulfate production wastewater. The wastewater is reduction wastewater generated during the production process of a chemical plant in Jiangsu Province. The reduction wastewater contains approximately 0.2% by mass of 2,5-diaminotoluene sulfate. The water quality is characterized by: black-red color, pH = 2, COD = 19045 mg / L, chroma of 20,000 times, and salt content (TDS) of 7%.

[0113] Take 2000mL of the above wastewater sample according to Figure 1 The process flow is as follows:

[0114] S1, prepare the separating agent: take 100 mL of cyclohexane acid, 300 mL of 2-ethylhexyl phosphoric acid, 200 mL of isomeric alcohol and 400 mL of aviation kerosene and mix them to obtain 1000 mL of separating agent;

[0115] S2, complex extraction: adjust the pH of 2000 mL of the above wastewater sample to 6-7, add 400 mL of the separating agent of S1 to the wastewater sample, fully mix and react at room temperature, react for 30 minutes, stand and separate, the upper layer is the separated phase, and the lower layer is the first aqueous phase. After extracting water from the first aqueous phase, it is concentrated and crystallized into salt; wherein, the reaction time of complex extraction includes the time for full reaction.

[0116] S3, extractant regeneration: add a 10% by mass sulfuric acid solution to the separated phase, wherein the volume ratio of the separated phase to the hydrochloric acid solution is 10:1, and fully react in a 40°C water bath for about 30 minutes. After standing and separating the layers, the lower layer is the recovery phase and the upper layer is the separating agent regeneration phase. The separating agent regeneration phase is used for the recycling treatment of 2,5-diaminotoluene sulfate production wastewater; wherein, the reaction time of the extractant regeneration includes the time for the full reaction to be complete.

[0117] S4, treatment of the recovery phase: add liquid alkali with a mass fraction of 32% to the recovery phase, or other concentrations of liquid alkali, and adjust the pH of the solution to 7. Experimental investigations have found that adjusting the pH to 6.5-7.5 does not affect the recovery. After fully reacting for 30 minutes, filter out tar and other impurities, add sulfuric acid solution to adjust the pH of the filtrate to about 2, and adjust the pH value to 1.5-2.5. Then add a saturated sodium sulfate solution and cool it to about 10°C. The precipitated solid substance is 2,5-diaminotoluene sulfate, and the calculated recovery rate is 75%.

[0118] In S3, the acidic solution can also be a sulfuric acid solution. Whether it is a sulfuric acid solution or a hydrochloric acid solution, the concentration used is 10-20% by mass. If it is lower than 10%, the amount of acidic solution added is large. If it is higher than 20%, the concentration is too high, which not only easily causes unnecessary side reactions, but also may be detrimental to subsequent processes. The selection of an appropriate concentration of the acidic solution is related to its usage. Specifically, the concentration of the acidic solution is 10-20%, and the volume ratio of the acidic solution to the separation phase satisfies 1:(5-10).

[0119] Table 5 Recycling and treatment status list

[0120]

[0121] Example 2-1

[0122] A method for recycling and treating wastewater from the production of 2,5-diaminotoluene sulfate is disclosed, which differs from Example 2 in that:

[0123] In S4, the mixture was cooled to about 0°C, and the precipitated solid substance was 2,5-diaminotoluene sulfate, with a calculated recovery rate of 82.5%.

[0124] Table 6 Recycling and treatment status list

[0125]

[0126] Example 2-2

[0127] Disclosed is a method for recycling and treating 2,5-diaminotoluene sulfate production wastewater. The wastewater is reduction wastewater generated during the production process of a chemical plant in Ningxia. The reduction wastewater contains 0.25% by mass of 2,5-diaminotoluene sulfate. The water quality is as follows: wine red in color, pH = 1, COD = 22220 mg / L, chroma of 20,000 times, and salt content (TDS) of 6%.

[0128] Take 2000mL of the above wastewater sample according to Figure 1 The process flow is as follows:

[0129] S1, prepare the separating agent: take 100 mL of cyclohexane acid, 300 mL of 2-ethylhexyl phosphoric acid, 200 mL of isomeric alcohol and 400 mL of aviation kerosene and mix them to obtain 1000 mL of separating agent;

[0130] S2, complex extraction: adjust the pH of 2000mL of wastewater sample to 7, then add 400mL of separating agent from S1, mix thoroughly and react at room temperature for 35min, let it stand to separate into layers, the upper layer is the separation phase, the lower layer is the first aqueous phase, extract the water from the first aqueous phase, and then concentrate and crystallize into salt; wherein, the reaction time of complex extraction includes the time for full reaction.

[0131] S3, extractant regeneration: add a 10% by mass sulfuric acid solution to the separated phase, wherein the volume ratio of the separated phase to the hydrochloric acid solution is 8:1, and fully react in a 45°C water bath for about 30 minutes. After standing and separating the layers, the lower layer is the recovery phase and the upper layer is the separating agent regeneration phase. The separating agent regeneration phase is used for the recycling treatment of 2,5-diaminotoluene sulfate production wastewater; wherein, the reaction time of the extractant regeneration includes the time for the full reaction to be complete.

[0132] S4, treatment of the recovery phase: add liquid alkali with a mass fraction of 32% to the recovery phase, or other concentrations of liquid alkali, and adjust the pH of the solution to 7. Experimental investigations have found that adjusting the pH to 6.5-7.5 does not affect the recovery. After fully reacting for 30 minutes, filter out tar and other impurities, add sulfuric acid solution to adjust the pH of the filtrate to about 2, and adjust the pH value to 1.5-2.5. Then add a saturated sodium sulfate solution and cool it to about 10°C. The precipitated solid substance is 2,5-diaminotoluene sulfate, and the calculated recovery rate is 71.2%.

[0133] In S3, the acidic solution can also be a sulfuric acid solution. Whether it is a sulfuric acid solution or a hydrochloric acid solution, the concentration used is 10-20% by mass. If it is lower than 10%, the amount of acidic solution added is large. If it is higher than 20%, the concentration is too high, which not only easily causes unnecessary side reactions, but also may be detrimental to subsequent processes. The selection of an appropriate concentration of the acidic solution is related to its usage. Specifically, the concentration of the acidic solution is 10-20%, and the volume ratio of the acidic solution to the separation phase satisfies 1:(5-10).

[0134] Table 7 Recycling and treatment status list

[0135]

[0136] Since heavy chemical wastewater and reduced wastewater are discharged separately via different pathways in the actual production of 2,5-diaminotoluene sulfate, the separate treatment and recovery methods described in the above embodiment are adopted. If the wastewater contains both heavy chemical wastewater and reduced wastewater, the method (3) protected by this application can be used, and the treatment effect is similar to that of the above embodiment, which is not described in detail in this application.

[0137] In summary, the treatment method is simple to operate and has certain economic benefits. In addition, the extractant of the present application is regenerable, and the COD of the first and second aqueous phases obtained by treatment is low, the color is light, and they have good biodegradability. After treatment with the currently mature biochemical system, the water or recovered salt can be recycled with high value.

[0138] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0139] The above description is merely a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for recycling wastewater from the production of 2,5-diaminotoluene sulfate, characterized in that: include: The pH of the 2,5-diaminotoluene sulfate production wastewater was adjusted to neutral, and a separating agent was added. The separating agent contained the following components in the following volume percentages: Complexing agent: 10% to 40%; the complexing agent comprises one or a combination of two or more of cyclohexane acid, 2-ethylhexyl phosphoric acid or 5,8-dinonyl-2-naphthalenesulfonic acid; Cosolvent: 10% to 20%; the cosolvent is an isomeric alcohol with a carbon chain of 8 to 20; The rest is diluent; After the reaction, the mixture was allowed to stand and separate into the lower layer as the first aqueous phase and the upper layer as the separated phase; An acidic solution is added to the separated phase, and after the reaction, the mixture is allowed to stand for separation to obtain a lower layer as a recovery phase and an upper layer as a separation agent regeneration phase, wherein the separation agent regeneration phase is used for cyclic treatment of 2,5-diaminotoluene sulfate production wastewater; The processing method of the recovered phase includes any one of the following: (1) adding an alkaline solution to the recovered phase to adjust the pH to 6.5-7.5, and recovering o-toluidine; (2) adding an alkaline solution to the recovered phase to adjust the pH to 6.5-7.5, filtering after the reaction, adjusting the pH of the filtrate to 1.5-2.5, and then adding a sulfate solution to recover 2,5-diaminotoluene sulfate; (3) adding an alkaline solution to the recovered phase to adjust the pH to 6.5-7.5, allowing the phase to stand for separation after the reaction to obtain an upper layer of recovered o-toluidine and a lower layer of a third aqueous phase, filtering the third aqueous phase, adjusting the pH of the filtrate to 1.5-2.5, and then adding a sulfate solution to recover 2,5-diaminotoluene sulfate.

2. The recycling method according to claim 1, characterized in that: In method (1), An alkaline solution is added to the recovered phase to adjust the pH to 6.5-7.

5. After the reaction, the phase is allowed to stand for separation to obtain a lower layer as the second aqueous phase and an upper layer as the recovered o-toluidine.

3. The recycling method according to claim 2, characterized in that: In method (1), the reaction is a room temperature reaction; The first aqueous phase and the second aqueous phase are subjected to evaporation and desalination treatment.

4. The recycling method according to claim 1, characterized in that: In method (2), Adding an alkaline solution to the recovered phase to adjust the pH to 6.5-7.5, filtering after the reaction, adjusting the pH of the filtrate to 1.5-2.5, adding a sulfate solution, cooling at low temperature, and precipitating 2,5-diaminotoluene sulfate; The low-temperature cooling temperature is 0-10°C.

5. The recycling method according to claim 1, characterized in that: In method (3), An alkaline solution is added to the recovered phase to adjust the pH to 6.5-7.

5. After the reaction, the phase is allowed to stand for separation to obtain an upper layer as the recovered o-toluidine and a lower layer as the third aqueous phase. The third aqueous phase is filtered, and the pH of the filtrate is adjusted to 1.5-2.

5. A sulfate solution is then added, and the phase is cooled at low temperature to precipitate 2,5-diaminotoluene sulfate. The low-temperature cooling temperature is 0-10°C.

6. The recycling method according to any one of claims 1 to 5, characterized in that: The alkaline solution comprises any one of sodium hydroxide, potassium hydroxide and ammonia water; The sulfate solution comprises an aqueous solution of any one of sodium sulfate and potassium sulfate.

7. The recycling method according to claim 6, characterized in that: The sulfate solution is a saturated solution at normal temperature and pressure.

8. The recycling method according to any one of claims 1 to 5, characterized in that: The acidic solution reacts with the separated phase in a water bath at 40-50° C.; The volume ratio of the acidic solution to the separated phase is 1:(5-10); The mass fraction of the acidic solution is 10% to 20%.

9. The recycling method according to claim 8, characterized in that: The acidic solution is a hydrochloric acid solution or a sulfuric acid solution.

10. The recycling method according to any one of claims 1 to 5, characterized in that: The volume of the separating agent accounts for 5% to 30% of the volume of the 2,5-diaminotoluene sulfate production wastewater.

11. The recycling method according to claim 1, characterized in that: The diluent comprises one or both of aviation kerosene and diesel.

Images