Process for treating and recycling 5-nitro-o-sulfonic acid sulfonation waste acid

Abstract

The invention belongs to the technical field of treatment and recovery of sulfonation waste acid, particularly relates to a process for treating and recovering 5-nitro-o-sulfonic acid sulfonation waste acid, and aims to solve the problems of high cost and complex process of most of technologies for purifying and utilizing the waste acid in the prior art. The method comprises the following steps: 1, pretreatment: adding activated carbon into a sulfonated waste acid receiver, and stirring until the activated carbon is saturated in adsorption; step 2, filtering: squeezing through a filter press; 3, advanced oxidation: heating the filtered pretreated waste acid, slowly dropwise adding an oxidizing agent, keeping the temperature, and carrying out advanced oxidation, so that the appearance of the pretreated waste acid becomes transparent, and the COD is further reduced to be within 300mg / L; according to the method, the 5-nitro-o-sulfonic acid sulfonated waste acid can be effectively treated and recycled, cyclic utilization of resources is achieved, meanwhile, environmental pollution is reduced, and the process has the advantages of being easy and convenient to operate, remarkable in effect, controllable in cost and the like and has high application value.

Description

Technical Field

[0001] The invention relates to the technical field of treatment and recovery of sulfonation waste acid, and in particular to a process for treatment and recovery of 5-nitro-o-sulfonic acid sulfonation waste acid. Background Art

[0002] Sulfuric acid is an inorganic compound with the chemical formula H2SO4. It is the most important oxygen-containing acid of sulfur. Pure sulfuric acid is a colorless oily liquid with a relative density of 1.84. Sulfuric acid is the most active binary inorganic strong acid and can react with most metals. High concentrations of sulfuric acid have strong water absorption and can be used as a dehydrating agent to carbonize wood, paper, cotton and linen fabrics, biological skins and other carbohydrate-containing substances. When mixed with water, it will also release a large amount of heat energy. It has strong corrosiveness and oxidizing properties, so it needs to be used with caution. It is also an important industrial raw material that can be used to make fertilizers, drugs, explosives, pigments, detergents, batteries, etc. It is also widely used in industries such as petroleum purification, metal smelting, and dyes. It is often used as a chemical reagent and can be used as a dehydrating agent and sulfonating agent in organic synthesis.

[0003] The sulfonation process usually uses fuming sulfuric acid as the sulfonating agent. In most reactions, sulfuric acid only serves as a solvent and heat transfer medium and does not participate in the sulfonation reaction. Therefore, a large amount of waste acid is generated in the process.

[0004] Since the sulfonation reaction releases a great deal of heat, and the concentration of sulfuric acid at this time is extremely high and has strong oxidizing properties, the difference in conditions during the reaction causes the process to produce a large amount of over-sulfonated or poly-sulfonated dark by-products, causing the color of the sulfuric acid to become black-brown and have a very high COD, some even as high as hundreds of thousands.

[0005] Although many technologies have been developed in recent years to purify and utilize this type of waste acid, most of them are costly and complex. Therefore, a process for treating and recovering 5-nitro-o-sulfonic acid sulfonation waste acid is needed to solve the above-mentioned problems. Summary of the invention

[0006] The invention provides a process for treating and recovering 5-nitro orthosulfonic acid sulfonation waste acid, which solves the problem that many existing technologies are used to purify and utilize such waste acid, but most of them are high in cost and complicated in process.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid comprises the following steps:

[0009] Step 1:

[0010] Pretreatment: Add activated carbon to the sulfonation waste acid receiver and stir until the activated carbon is saturated with adsorption;

[0011] Step 2:

[0012] Filtration: Pressing through a filter press;

[0013] Step 3:

[0014] Advanced oxidation: The filtered pre-treated waste acid is subjected to advanced oxidation by heating and slowly adding oxidants to keep the temperature, so that its appearance becomes transparent and COD is further reduced to less than 300 mg / L;

[0015] Step 4:

[0016] Standardized configuration: Qualified waste acid can be configured to reach the required content of the original product and stored for application.

[0017] Preferably, in step 1, activated carbon can play an adsorption role, and the amount used is determined according to the specific gravity, content, COD and other values ​​of the waste acid, and the added amount is 1‰ to 1% of the volume of the waste acid.

[0018] Preferably, in step 2, the waste acid is continuously tested during the pressing process to remove most of the COD and sulfonated by-products. The filtered filter cake can be regenerated with activated carbon, and whether to recover the material can also be considered based on the quality of the filter cake.

[0019] Preferably, in step 3, the specific amount used is:

[0020] a. The oxidant can be hydrogen peroxide (content 3% to 30%), the amount of which is 1% to 9% of the volume of the waste acid;

[0021] b. Or nitric acid (content 30% to 68%), the amount used is 1‰ to 9‰ of the volume of the waste acid;

[0022] c. The oxidant titration rate is controlled at 1L / min~9L / min;

[0023] d. The dropping temperature is controlled at 38℃~95℃;

[0024] e. The insulation time is 1h to 6h;

[0025] f..After the oxidation is completed, the detection end point COD should be ≤300mg / L; the chromaticity should be ≤245 dark blue;

[0026] g. The advanced oxidation process is divided into intermittent treatment and continuous treatment. The intermittent treatment adopts single-pot treatment with low processing capacity, single process visualization and gentle control. The continuous advanced oxidation adopts a mixer to allow the oxidant and acid to enter at a uniform speed, stay in the oxidation tower for a certain time (1h to 6h), discharge at the top of the tower, and enter the next step after heat exchange with the mixer (heat exchange efficiency is 75% to 95%).

[0027] Preferably, in the step 1, 5000 L of waste acid generated by the production of 5-nitro-o-sulfonic acid is pumped into a pre-treatment unit, an appropriate amount of activated carbon (5-10 kg) is added to the pre-treatment unit, stirring is started, and the pre-treatment unit is set aside after active adsorption is saturated.

[0028] Preferably, in step 2, the pretreatment liquid is pumped into a plate-and-frame filter press for squeezing. During the squeezing process, no activated carbon can leak through the filter cloth, and the moisture content of the pressed filter cake must be strictly controlled at 30% to 55%.

[0029] Preferably, in the step 1, after the pretreated waste acid is heat exchanged, it is uniformly pumped into a mixer together with 100-210 L of hydrogen peroxide, and the temperature is slowly raised to 50° C.-80° C., and then it enters an oxidation tower at a uniform speed.

[0030] Preferably, the residence time in the oxidation tower is controlled at 2h-3.5h, the speed is controlled at 2.5L / min-3.5L / min, and the time is 40min-65min.

[0031] Preferably, the detected COD is 208, 223, 285 and 291 mg / L, respectively, and the chromaticity is 196, 135, 226 and 232 dark blue. After completion, it comes out from the top of the tower and exchanges heat with the mixer to achieve continuous treatment.

[0032] Preferably, the treated acid solution is configured into 75% sulfuric acid and then used in a controlled manner without any influence on product quality.

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

[0034] Resource recycling: Through activated carbon adsorption, filtration and advanced oxidation steps, impurities and pollutants in waste acid are effectively removed, so that it can be reconfigured into sulfuric acid products that meet production requirements, realizing resource recycling and reducing production costs.

[0035] Environmental protection: During the waste acid treatment process, the pollution of the environment by waste acid is significantly reduced by removing harmful substances such as COD and sulfonation by-products. At the same time, the recycling of activated carbon reduces the generation of waste and further reduces the environmental burden.

[0036] Economic benefits: The recycling of waste acid not only reduces the demand for purchasing new sulfuric acid, but also reduces the cost of waste acid treatment. In addition, the economic benefits are further improved through material recovery and the regeneration of activated carbon.

[0037] Process flexibility: This process provides two processing modes: intermittent processing and continuous processing, which can be flexibly selected according to actual production needs. Intermittent processing is suitable for small-scale or experimental production, while continuous processing is suitable for large-scale and high-efficiency production needs.

[0038] Product quality assurance: The COD value and color of the treated waste acid meet or exceed the standard requirements and can be safely used in the product production process without any negative impact on product quality.

[0039] Technological innovation: This process combines multiple technical means such as activated carbon adsorption and advanced oxidation to form a complete waste acid treatment and recovery system. This technological innovation not only improves the efficiency of waste acid treatment, but also provides reference experience and ideas for the treatment of similar wastewater.

[0040] The invention can effectively treat and recycle the waste acid of sulfonation of 5-nitro-o-sulfonic acid, realize the recycling of resources, and reduce environmental pollution. The process has the advantages of simple operation, significant effect, controllable cost, etc., and has high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The present invention provides a discontinuous treatment flow chart of a process for treating and recovering 5-nitro-o-sulfonic acid sulfonation waste acid;

[0042] Figure 2 The present invention provides a continuous processing flow chart of a process for treating and recovering 5-nitro-o-sulfonic acid sulfonation waste acid. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0044] Reference Figure 1-2 A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid comprises the following steps:

[0045] Step 1:

[0046] Pretreatment: Add activated carbon to the sulfonation waste acid receiver and stir until the activated carbon is saturated with adsorption;

[0047] Step 2:

[0048] Filtration: Pressing through a filter press;

[0049] Step 3:

[0050] Advanced oxidation: The filtered pre-treated waste acid is subjected to advanced oxidation by heating and slowly adding oxidants to keep the temperature, so that its appearance becomes transparent and COD is further reduced to less than 300 mg / L;

[0051] Step 4:

[0052] Standardized configuration: Qualified waste acid can be configured to reach the required content of the original product and stored for application.

[0053] In this embodiment, in step 1, activated carbon can play an adsorption role, and the amount used is determined according to the specific gravity, content, COD and other values ​​of the waste acid, and the added amount is 1‰ to 1% of the volume of the waste acid.

[0054] In step 2, the waste acid is continuously tested during the pressing process to remove most of the COD and sulfonated by-products. The filtered filter cake can be regenerated with activated carbon. Depending on the quality of the filter cake, it is also possible to consider whether to recycle the material. The COD reduced by this process is generally more than half of the total amount.

[0055] In step 3, the specific dosage is:

[0056] a. The oxidant can be hydrogen peroxide (content 3% to 30%), the amount of which is 1% to 9% of the volume of the waste acid;

[0057] b. Or nitric acid (content 30% to 68%), the amount used is 1‰ to 9‰ of the volume of the waste acid;

[0058] c. The oxidant titration rate is controlled at 1L / min~9L / min;

[0059] d. The dropping temperature is controlled at 38℃~95℃;

[0060] e. The insulation time is 1h to 6h;

[0061] f. After the oxidation is completed, the detection end point COD should be ≤300mg / L; the chromaticity should be ≤245 dark blue;

[0062] g. The advanced oxidation process is divided into intermittent treatment and continuous treatment. The intermittent treatment adopts single-pot treatment with low processing capacity, single process visualization and gentle control. The continuous advanced oxidation adopts a mixer to allow the oxidant and acid to enter at a uniform speed, stay in the oxidation tower for a certain time (1h to 6h), discharge at the top of the tower, and enter the next step after heat exchange with the mixer (heat exchange efficiency is 75% to 95%).

[0063] In this embodiment, first, 5000L of waste acid produced by the production of 5-nitro-o-sulfonic acid is pumped into a pre-treatment unit, 5kg of an appropriate amount of activated carbon is added to the pre-treatment unit, stirring is started, and after the active adsorption is saturated, it is set aside.

[0064] 2. The above-mentioned pre-treated liquid is pumped into a plate and frame filter press for squeezing. During the squeezing process, no activated carbon can leak through the filter cloth, and the moisture content of the squeezed filter cake must be strictly controlled at 30% to 55%.

[0065] 3. In this example, the filter cake is subjected to material recovery treatment, during which the activated carbon is recovered and regenerated, and the material is returned to the product production process for refining, which will not be elaborated here.

[0066] 4. Pretreatment: Raise the temperature of the waste acid solution to 50℃, slowly add hydrogen peroxide, the speed is controlled at 2.5L / min, and the time is 40min-45min. Keep warm for 2h after adding, and detect COD291mg / L, color 232 black.

[0067] The above acid solution can be heat exchanged with the next batch of pre-treated waste acid, the hot acid can be subjected to advanced oxidation, and the cold acid can be cooled to room temperature to be configured into 75% sulfuric acid before being applied. This will not affect the product quality.

[0068] Embodiment 2

[0069] Step 1:

[0070] Pretreatment: Add activated carbon to the sulfonation waste acid receiver and stir until the activated carbon is saturated with adsorption;

[0071] Step 2:

[0072] Filtration: Pressing through a filter press;

[0073] Step 3:

[0074] Advanced oxidation: The filtered pre-treated waste acid is subjected to advanced oxidation by heating and slowly adding oxidants to keep the temperature, so that its appearance becomes transparent and COD is further reduced to less than 300 mg / L;

[0075] Step 4:

[0076] Standardized configuration: Qualified waste acid can be configured to reach the required content of the original product and stored for application.

[0077] In this embodiment, in step 1, activated carbon can play an adsorption role, and the amount used is determined according to the specific gravity, content, COD and other values ​​of the waste acid, and the added amount is 1‰ to 1% of the volume of the waste acid.

[0078] In step 2, the waste acid is continuously tested during the pressing process to remove most of the COD and sulfonated by-products. The filtered filter cake can be regenerated with activated carbon. Depending on the quality of the filter cake, it is also possible to consider whether to recycle the material. The COD reduced by this process is generally more than half of the total amount.

[0079] In step 3, the specific dosage is:

[0080] a. The oxidant can be hydrogen peroxide (content 3% to 30%), the amount of which is 1% to 9% of the volume of the waste acid;

[0081] b. Or nitric acid (content 30% to 68%), the amount used is 1‰ to 9‰ of the volume of the waste acid;

[0082] c. The oxidant titration rate is controlled at 1L / min~9L / min;

[0083] d. The dropping temperature is controlled at 38℃~95℃;

[0084] e. The insulation time is 1h to 6h;

[0085] f. After the oxidation is completed, the detection end point COD should be ≤300mg / L; the chromaticity should be ≤245 dark blue;

[0086] g. The advanced oxidation process is divided into intermittent treatment and continuous treatment. The intermittent treatment adopts a single kettle treatment, which has low treatment capacity, single process visualization, and gentle control; the continuous advanced oxidation adopts a mixer to allow the oxidant and acid to enter at a uniform speed, stay in the oxidation tower for a certain time (1h~6h), discharge at the top of the tower, and enter the next step after heat exchange with the mixer (heat exchange efficiency is 75%~95%).

[0087] 1. 5000L of waste acid produced by the production of 5-nitro-o-sulfonic acid is pumped into the pre-treatment unit. An appropriate amount of activated carbon (10kg) is added to the pre-treatment unit. Stirring is started. After the active adsorption is saturated, it is ready for use.

[0088] 2. The above-mentioned pre-treated liquid is pumped into a plate and frame filter press for squeezing. During the squeezing process, no activated carbon can leak through the filter cloth, and the moisture content of the squeezed filter cake must be strictly controlled at 30% to 55%.

[0089] 3. In this example, the filter cake is subjected to material recovery treatment, during which the activated carbon is recovered and regenerated, and the material is returned to the product production process for refining, which will not be elaborated here.

[0090] 4. Pretreatment: Raise the temperature of the waste acid solution to 80℃, slowly add hydrogen peroxide, the speed is controlled at 3.5L / min, and the time is 60min~65min. Keep warm for 3.5h after adding, and detect COD208mg / L, chromaticity 196 black.

[0091] 5. The above acid solution can be heat exchanged with the next batch of pre-treated waste acid, and the hot acid can be subjected to advanced oxidation, and the cold acid can be cooled to room temperature to be configured into 75% sulfuric acid, and then applied for use. It will not affect the product quality.

[0092] Embodiment 3,

[0093] Step 1:

[0094] Pretreatment: Add activated carbon to the sulfonation waste acid receiver and stir until the activated carbon is saturated with adsorption;

[0095] Step 2:

[0096] Filtration: Pressing through a filter press;

[0097] Step 3:

[0098] Advanced oxidation: The filtered pre-treated waste acid is subjected to advanced oxidation by heating and slowly adding oxidants to keep the temperature, so that its appearance becomes transparent and COD is further reduced to less than 300 mg / L;

[0099] Step 4:

[0100] Standardized configuration: Qualified waste acid can be configured to reach the required content of the original product and stored for application.

[0101] In this embodiment, in step 1, activated carbon can play an adsorption role, and the amount used is determined according to the specific gravity, content, COD and other values ​​of the waste acid, and the added amount is 1‰ to 1% of the volume of the waste acid.

[0102] In step 2, the waste acid is continuously tested during the pressing process to remove most of the COD and sulfonated by-products. The filtered filter cake can be regenerated with activated carbon. Depending on the quality of the filter cake, it is also possible to consider whether to recycle the material. The COD reduced by this process is generally more than half of the total amount.

[0103] In step 3, the specific dosage is:

[0104] a. The oxidant can be hydrogen peroxide (content 3% to 30%), the amount of which is 1% to 9% of the volume of the waste acid;

[0105] b. Or nitric acid (content 30% to 68%), the amount used is 1‰ to 9‰ of the volume of the waste acid;

[0106] c. The oxidant titration rate is controlled at 1L / min~9L / min;

[0107] d. The dropping temperature is controlled at 38℃~95℃;

[0108] e. The insulation time is 1h to 6h;

[0109] f. After the oxidation is completed, the detection end point COD should be ≤300mg / L; the chromaticity should be ≤245 dark blue;

[0110] g. The advanced oxidation process is divided into intermittent treatment and continuous treatment. The intermittent treatment adopts a single kettle treatment, which has low treatment capacity, single process visualization, and gentle control; the continuous advanced oxidation adopts a mixer to allow the oxidant and acid to enter at a uniform speed, stay in the oxidation tower for a certain time (1h~6h), discharge at the top of the tower, and heat exchange with the mixer (heat exchange efficiency is 75%~95%) before entering the next step

[0111] 1. 5000L of waste acid produced by the production of 5-nitro-o-sulfonic acid is pumped into the pre-treatment unit. 5kg of activated carbon is added to the pre-treatment unit, and stirring is started. After the active adsorption is saturated, it is set aside for use.

[0112] 2. The above-mentioned pre-treated liquid is pumped into a plate and frame filter press for squeezing. During the squeezing process, no activated carbon can leak through the filter cloth, and the moisture content of the squeezed filter cake must be strictly controlled at 30% to 55%.

[0113] 3. In this example, the filter cake is subjected to material recovery treatment, during which the activated carbon is recovered and regenerated, and the material is returned to the product production process for refining, which will not be elaborated here.

[0114] Fourth, after the pre-treated waste acid is heat exchanged, it is uniformly pumped into the mixer together with hydrogen peroxide (100L), and slowly heated to 50°C, and uniformly enters the oxidation tower. The residence time in the oxidation tower is controlled at 2h. After completion, it comes out from the top of the tower and exchanges heat with the mixer to achieve continuous treatment. The COD of the acid solution is detected to be 285mg / L, and the chromaticity is 226 black.

[0115] 5. After the treated acid is prepared into 75% sulfuric acid, it can be applied for use. It will not affect the product quality.

[0116] Embodiment 4

[0117] Step 1:

[0118] Pretreatment: Add activated carbon to the sulfonation waste acid receiver and stir until the activated carbon is saturated with adsorption;

[0119] Step 2:

[0120] Filtration: Pressing through a filter press;

[0121] Step 3:

[0122] Advanced oxidation: The filtered pre-treated waste acid is subjected to advanced oxidation by heating and slowly adding oxidants to keep the temperature, so that its appearance becomes transparent and COD is further reduced to less than 300 mg / L;

[0123] Step 4:

[0124] Standardized configuration: Qualified waste acid can be configured to reach the required content of the original product and stored for application.

[0125] In this embodiment, in step 1, activated carbon can play an adsorption role, and the amount used is determined according to the specific gravity, content, COD and other values ​​of the waste acid, and the added amount is 1‰ to 1% of the volume of the waste acid.

[0126] In step 2, the waste acid is continuously tested during the pressing process to remove most of the COD and sulfonated by-products. The filtered filter cake can be regenerated with activated carbon. Depending on the quality of the filter cake, it is also possible to consider whether to recycle the material. The COD reduced by this process is generally more than half of the total amount.

[0127] In step 3, the specific dosage is:

[0128] a. The oxidant can be hydrogen peroxide (content 3% to 30%), the amount of which is 1% to 9% of the volume of the waste acid;

[0129] b. Or nitric acid (content 30% to 68%), the amount used is 1‰ to 9‰ of the volume of the waste acid;

[0130] c. The oxidant titration rate is controlled at 1L / min~9L / min;

[0131] d. The dropping temperature is controlled at 38℃~95℃;

[0132] e. The insulation time is 1h to 6h;

[0133] f. After the oxidation is completed, the detection end point COD should be ≤300mg / L; the chromaticity should be ≤245 dark blue;

[0134] g. The advanced oxidation process is divided into intermittent treatment and continuous treatment. The intermittent treatment adopts a single kettle treatment, which has low treatment capacity, single process visualization, and gentle control; the continuous advanced oxidation adopts a mixer to allow the oxidant and acid to enter at a uniform speed, stay in the oxidation tower for a certain time (1h~6h), discharge at the top of the tower, and enter the next step after heat exchange with the mixer (heat exchange efficiency is 75%~95%).

[0135] 1. 5000L of waste acid produced by the production of 5-nitro-o-sulfonic acid is pumped into the pre-treatment unit. An appropriate amount of activated carbon (10kg) is added to the pre-treatment unit. Stirring is started. After the active adsorption is saturated, it is ready for use.

[0136] 2. The above-mentioned pre-treated liquid is pumped into a plate and frame filter press for squeezing. During the squeezing process, no activated carbon can leak through the filter cloth, and the moisture content of the squeezed filter cake must be strictly controlled at 30% to 55%.

[0137] 3. In this example, the filter cake is subjected to material recovery treatment, during which the activated carbon is recovered and regenerated, and the material is returned to the product production process for refining, which will not be elaborated here.

[0138] Fourth, after the pre-treated waste acid is heat exchanged, it is uniformly pumped into the mixer together with hydrogen peroxide (210L), and slowly heated to 80℃, and uniformly enters the oxidation tower. The residence time in the oxidation tower is controlled to be 3h. After completion, it comes out from the top of the tower and exchanges heat with the mixer to achieve continuous treatment. The COD of the acid solution is 223mg / L and the chromaticity is 135 black.

[0139] 5. After the treated acid is configured into 75% sulfuric acid, it can be applied for use without any impact on product quality.

[0140] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid, characterized in that: The following steps are involved: Step 1: Pretreatment: Add activated carbon to the sulfonation waste acid receiver and stir until the activated carbon is saturated with adsorption; Step 2: Filtration: Pressing through a filter press; Step 3: Advanced oxidation: The filtered pre-treated waste acid is subjected to advanced oxidation by heating and slowly adding oxidants to keep the temperature, so that its appearance becomes transparent and COD is further reduced to less than 300 mg / L; Step 4: Standardized configuration: Qualified waste acid can be configured to reach the required content of the original product and stored for application.

2. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 1, characterized in that: In the step 1, the activated carbon can play an adsorption role, and the amount used is determined according to the specific gravity, content, COD and other values ​​of the waste acid, and the added amount is 1‰ to 1% of the volume of the waste acid.

3. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 1, characterized in that: In step 2, the waste acid is continuously tested during the pressing process to remove most of the COD and sulfonated by-products. The filtered filter cake can be regenerated with activated carbon, and whether to recycle the material can also be considered based on the quality of the filter cake.

4. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 1, characterized in that: In the step 3, the specific amount is: a. The oxidant can be hydrogen peroxide (content 3% to 30%), the amount of which is 1% to 9% of the volume of the waste acid; b. Or nitric acid (content 30% to 68%), the amount used is 1‰ to 9‰ of the volume of the waste acid; c. The oxidant titration rate is controlled at 1L / min~9L / min; d. The dropping temperature is controlled at 38℃~95℃; e. The insulation time is 1h to 6h; f..After the oxidation is completed, the detection end point COD should be ≤300mg / L; the chromaticity should be ≤245 dark blue; g. The advanced oxidation process is divided into intermittent treatment and continuous treatment. The intermittent treatment adopts single-pot treatment with low processing capacity, single process visualization and gentle control. The continuous advanced oxidation adopts a mixer to allow the oxidant and acid to enter at a uniform speed, stay in the oxidation tower for a certain time (1h to 6h), discharge at the top of the tower, and enter the next step after heat exchange with the mixer (heat exchange efficiency is 75% to 95%).

5. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 1, characterized in that: In the step 1, 5000L of waste acid generated by the production of 5-nitro-o-sulfonic acid is pumped into a pre-treatment unit, an appropriate amount of activated carbon (5-10kg) is added to the pre-treatment unit, stirring is started, and the pre-treatment unit is set aside after active adsorption is saturated.

6. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 1, characterized in that: In the step 2, the pre-treatment liquid is pumped into a plate-and-frame filter press for squeezing. During the squeezing process, no activated carbon can leak through the filter cloth, and the moisture content of the pressed filter cake must be strictly controlled at 30% to 55%.

7. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 1, characterized in that: In the step 1, the pretreated waste acid is heat exchanged and then uniformly pumped into a mixer together with 100-210 L of hydrogen peroxide, and the temperature is slowly raised to 50° C.-80° C., and then uniformly introduced into an oxidation tower.

8. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 7, characterized in that: The residence time in the oxidation tower is controlled at 2h-3.5h, the speed is controlled at 2.5L / min-3.5L / min, and the time is 40min-65min.

9. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 7, characterized in that: The detected COD were 208, 223, 285 and 291 mg / L respectively, and the chromaticity was 196, 135, 226 and 232 dark blue. After completion, it came out from the top of the tower and exchanged heat with the mixer to achieve continuous treatment.

10. A process for treating and recovering waste acid from sulfonation of 5-nitro-o-sulfonic acid according to claim 7, characterized in that: The treated acid solution is then mixed into 75% sulfuric acid and used. This will not affect product quality.

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