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CN-122010366-A - Pretreatment method of chemical wastewater

CN122010366ACN 122010366 ACN122010366 ACN 122010366ACN-122010366-A

Abstract

The invention relates to the technical field of chemical wastewater, and discloses a pretreatment method of chemical wastewater, which solves the problems of high treatment cost, low organic matter removal rate and poor resource utilization of the existing anthranilic acid, methyl anthranilate and saccharin sodium production wastewater. The method comprises the steps of firstly pretreating salt components of sewage to eliminate the interference of inorganic salts on subsequent reactions, then carrying out hydrolysis/alkaline hydrolysis treatment, then directionally converting anthranilic acid components into high-added-value 2- ((5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl) diazo) benzoic acid byproducts through diazotization-coupling reaction, and finally cooling to separate out and recycle crude phthalic acid. The invention has the advantages of high utilization rate of the anthranilic acid component in the sewage reaching more than 99.9 percent, low treatment cost, less equipment investment, short process flow, high recycling benefit and thorough sewage treatment.

Inventors

  • YE HUATIAN
  • CHEN JINYANG
  • WANG JIE

Assignees

  • 陆吾(山东)化工技术有限公司

Dates

Publication Date
20260512
Application Date
20260414

Claims (7)

  1. 1. The pretreatment method of the chemical wastewater is characterized by comprising the following steps: (1) Salt component pretreatment, namely adjusting the parameters of a sewage system according to the content and the type of salt components in chemical sewage to be treated, and eliminating the interference of multi-component salt on subsequent chemical reaction to obtain pretreated sewage; the chemical wastewater to be treated is any one of anthranilic acid production wastewater, anthranilic acid methyl ester production wastewater and saccharin sodium production wastewater; (2) Hydrolysis and alkaline hydrolysis treatment, namely performing hydrolysis/alkaline hydrolysis treatment on the pretreated sewage obtained in the step (1), removing ester groups and amide groups in the sewage, and converting organic components into active components containing amino groups to obtain alkaline hydrolysis sewage; (3) Determining the amino group content A in the alkaline hydrolysis sewage obtained in the step (2) by adopting a titration method; (4) Acid regulation and pre-cooling, namely adding acid into alkaline hydrolysis sewage, regulating the pH value of the system to 3.0-3.5, adding concentrated hydrochloric acid, cooling the system to-5~0 ℃, and carrying out heat preservation and stirring to obtain a system to be diazotized; (5) Diazotizing reaction, namely preparing 30% sodium nitrite solution by mass, dripping the sodium nitrite solution into a system to be diazotized, controlling the temperature of the system to be-5~0 ℃ in the dripping process, detecting a reaction end point through starch potassium iodide test paper until the test paper is bluish, stopping dripping, and carrying out heat preservation reaction at-5~0 ℃ after dripping to obtain diazonium salt reaction liquid; (6) Preparing a coupling solution, namely preparing a coupling solution containing 1,3, 5-pyrazolone according to the dosage M of the sodium nitrite solution in the step (5); (7) The preparation method of the coupling solution comprises the steps of adding 1.6M of water, M/12 of sodium carbonate, 0.5M of 32% liquid alkali by mass fraction and 2M/3 of 1,3, 5-pyrazolone into a coupling kettle according to mass proportion, stirring until materials are completely dissolved, and cooling to 0 ℃ to obtain the coupling solution; (8) And (2) recycling byproducts, namely adding hydrochloric acid into the coupling reaction liquid to adjust the pH value of the system to 2.5-3.0, heating to 70 ℃, preserving heat, stirring, cooling, performing solid-liquid separation to obtain a solid first byproduct 2- ((5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl) diaza) benzoic acid, cooling the separated filtrate to 0-10 ℃, precipitating the solid, filtering to obtain a second byproduct crude phthalic acid, and finishing sewage pretreatment.
  2. 2. The pretreatment method of chemical wastewater according to claim 1, wherein in the step (1), the specific method of pretreatment of the salt component is as follows: If the sewage to be treated is the sewage produced by anthranilic acid, the salt component of the sewage is pure sodium chloride, and the sewage is directly used as the pretreatment sewage to enter the step (2) without salt treatment; If the sewage to be treated is the sewage produced by the methyl anthranilate, the salt components of the sewage are sodium carbonate and sodium bicarbonate, concentrated hydrochloric acid is added into the sewage, the pH value of the system is regulated to 6.0-6.5, and the pretreated sewage is obtained after uniform stirring; If the sewage to be treated is saccharin sodium production sewage, adding hydrochloric acid into the sewage to adjust the pH value to 1.0-3.0, heating to 60-80 ℃, and carrying out heat preservation and stirring for 1h to obtain the pretreated sewage.
  3. 3. The pretreatment method of chemical wastewater according to claim 1, wherein in the step (2), the specific method of hydrolysis and alkaline hydrolysis is as follows: if the sewage to be treated is the sewage produced by anthranilic acid, the sewage is free of ester groups and amide groups, hydrolysis and alkaline hydrolysis are not needed, and the pretreated sewage is directly used as alkaline hydrolysis sewage to enter the step (3); If the sewage to be treated is the sewage produced by the methyl anthranilate, detecting the content of the methyl anthranilate in the sewage by liquid chromatography or gas chromatography through an external standard method, adding liquid alkali with the mole number of 1.1-1.2 times into the sewage, heating to 70-80 ℃ and stirring for reacting for 1h, or directly sending the sewage into a methanol recovery tower, and completing alkaline hydrolysis removal of ester groups while recovering the methanol by utilizing the heat energy of the methanol recovery tower to obtain alkaline hydrolysis sewage; If the sewage to be treated is saccharin sodium production sewage, firstly adding liquid alkali into the pretreated sewage to adjust the pH value of the system to 6.5-7.0, detecting the content of methyl anthranilate in the sewage by liquid chromatography or gas chromatography through an external standard method, adding 1.1-1.2 times of the liquid alkali in mole number into the sewage, heating to 70-80 ℃ and stirring for reacting for 1h to obtain alkaline hydrolysis sewage.
  4. 4. The pretreatment method of chemical wastewater according to claim 1, wherein in the step (3), the specific method for determining the amino group content A by the titration method is characterized in that a wastewater sample is accurately weighed, placed in a 150ml beaker, 5ml of concentrated hydrochloric acid is added, 50ml of distilled water is added after stirring uniformly at room temperature, the solution is cooled to below 15 ℃, titration is carried out by using sodium nitrite standard solution with known molar concentration Cmol/L, the titration process is continuously stirred, and real-time detection is carried out by using starch potassium iodide test paper, when the starch potassium iodide test paper shows stable bluish color, the titration is stopped, the volume vm L of the sodium nitrite standard solution consumed is recorded, and the mass percentage A of the amino group in the wastewater is calculated according to the following formula, wherein A=100×C×V×0.137/m is millimole mass of anthranilic acid, the unit is g/mmol, and m is the mass of the wastewater sample.
  5. 5. The pretreatment method of chemical wastewater according to claim 1, wherein in the step (4), the adding amount of the concentrated hydrochloric acid is measured according to 1.8 times of the product of the wastewater mass and the amino content A, the mass fraction of the concentrated hydrochloric acid is 30%, and the heat preservation and stirring time is 10min after the temperature is reduced to-5~0 ℃.
  6. 6. The pretreatment method of chemical wastewater according to claim 1, wherein in the step (7), the reaction time is 2 hours after the completion of the dropwise addition of the coupling solution.
  7. 7. The pretreatment method of chemical wastewater according to claim 1, wherein in the step (8), the temperature is raised to 70 ℃ and the stirring time is 0.5h.

Description

Pretreatment method of chemical wastewater Technical Field The invention relates to the technical field of chemical sewage, in particular to a pretreatment method of chemical sewage. Background In the fine chemical production process, anthranilic acid, methyl anthranilate and saccharin sodium are important medicine and food additive intermediates, and a large amount of high-concentration organic sewage can be produced in the production process. The main organic pollutants in the sewage generated by producing the anthranilic acid are phthalic acid and the anthranilic acid, the COD is 25000-40000 mg/L, the main organic pollutants in the sewage generated by producing the methyl anthranilate are phthalic acid, the anthranilic acid, the methyl anthranilate and the methyl anthranilate, the COD is 160000-200000 mg/L, the main organic pollutants in the sewage generated by producing the saccharin sodium are phthalic acid, the anthranilic acid and the methyl anthranilate, and the COD is 15000-20000 mg/L. The sewage has large discharge amount, contains most of organic matters which are difficult to degrade in benzene rings, has few biochemical groups and has great sewage treatment difficulty. The sewage treatment scheme disclosed at present mainly comprises MVR desalination, heavy metal complexation, flocculation precipitation, biochemical treatment, fenton oxidation, resin adsorption resolution and other processes, but the prior art has a plurality of defects which are difficult to overcome: The treatment cost is high, the equipment investment is large, the energy consumption is high, the process flow is complex, a large amount of dangerous solid waste and secondary waste gas can be generated in the treatment process, and the environmental protection burden of enterprises is heavy; the recovery rate of the characteristic organic pollutants in the sewage is low, the removal rate of the organic matters in the pretreated sewage is insufficient, the COD of the sewage cannot be greatly reduced, and the subsequent biochemical treatment load is extremely high; The method is simple in separating the anthranilic acid in the sewage, has high residue, has no effective treatment means on components such as methyl anthranilate, methyl anthranilate and the like in the sewage, and simultaneously does not realize separation and recovery of main impurity phthalic acid in the sewage; the recycling degree is extremely low, only the recycling of raw materials with low added value can be realized, even the recycling cannot be realized, and pollutants in sewage cannot be converted into products with economic value; inorganic salt in the sewage system is not pretreated, and the existence of the inorganic salt can cause the change of sewage components due to external conditions such as high heat and the like in the subsequent treatment process, so that the recovery rate and the treatment effect of organic pollutants are further reduced. Aiming at the problems, a method for recycling the anthranilic acid from the mother liquor wastewater, disclosed in CN102190590A, adopts a copper salt complexing process, needs to carry out multi-step repeated complexing and analysis, introduces a large amount of metal complexes into a system to generate new pollutants, a method for recycling the anthranilic acid from the mother liquor or the wastewater, disclosed in CN1923799, adopts an ion exchange resin process, has the problems of low recycling rate, limited treatment capacity and high resin regeneration cost, a preparation method for recycling the anthranilic acid from the saccharin wastewater, disclosed in CN103193665, also adopts a copper salt complexing process, increases a crude product decoloring refining step, has longer flow and higher cost, and a treatment method for the saccharin production wastewater, disclosed in CN104478028, adopts an extraction method to extract the anthranilic acid, has the problems of large consumption of an extractant, low extraction yield and high application difficulty of the extractant, can only extract a small amount of the anthranilic acid, and has no separation treatment effect on other organic components in the wastewater. In summary, the prior art cannot fundamentally solve the problem of treatment of the sewage generated in the production of anthranilic acid, and cannot simultaneously realize the sewage treatment targets of low cost, high removal rate and high resource utilization. Disclosure of Invention (One) solving the technical problems Aiming at the defects of the prior art, the invention provides a pretreatment method of chemical wastewater, which thoroughly separates organic pollutants in the wastewater, has high organic matter removal rate, simple process flow, small equipment investment and low treatment cost, can convert the pollutants in the wastewater into byproducts with high economic added value, realizes the recycling of the wastewater, and fundamentally solves the treatment problem of sewage pro