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CN-122010344-A - Method for recycling wastewater from production of hexazinone

CN122010344ACN 122010344 ACN122010344 ACN 122010344ACN-122010344-A

Abstract

The invention relates to a recycling method of waste water in the production of hexazinone, and belongs to the technical field of waste liquid recycling. The recovery method realizes the efficient separation of methanol and high-boiling impurities by pressure rectification and accurate temperature control of the tower top and tower bottom, cooperates with efficient stainless steel wire gauze packing, breaks through the efficiency bottleneck of a traditional single reducing agent by constructing a ferric oxide-activated carbon catalyst, sodium sulfite and circulating amine salt solution ternary cooperation detoxification system, realizes the synergy, realizes the efficient capture and high-value conversion of ammonia nitrogen by a chemometric accurate control and electrochemical innovation scheme, and innovates to adopt a carbon dioxide saturated aqueous solution with pH of 5.3-5.7 to replace an organic solvent for adsorption column analysis, greatly improves the analysis efficiency, and effectively eliminates VOCs emission and hazardous waste disposal risks caused by methanol use. The recovery method of the invention ensures recovery rate and purity and improves the recovery rate of organic amine and other substances.

Inventors

  • WANG DAOQING
  • LIU CHANGQING
  • ZHAO XINGXING
  • CHEN LIANG

Assignees

  • 安徽广信成辰科技有限公司

Dates

Publication Date
20260512
Application Date
20260316

Claims (10)

  1. 1. The recycling method of the hexazinone production wastewater is characterized by comprising the following steps of: S1, introducing a hexazinone reaction mother liquor into a pressurized rectifying tower, adopting a high-efficiency stainless steel wire mesh as a filler material, controlling the operation pressure to be 0.3-0.5 MPa, the tower top temperature to be 78-82 ℃, the tower bottom temperature to be 85-90 ℃, the reflux ratio to be 1.2-1.8, the residence time to be 25-35 min, collecting methanol at the tower top, and the tower bottom to be the rectified residual liquid; S2, introducing the rectified raffinate into a selective catalytic reduction reactor, regulating the pH to 6.5-7.5, heating to 35-45 ℃, adding an iron oxide-activated carbon composite catalyst and 25-35 wt% of sodium sulfite solution, wherein the adding amount of the iron oxide-activated carbon composite catalyst is 1.5-2.0% of the mass of the raffinate, and the adding amount of the sodium sulfite solution is 3-5 kg/m 3 of the raffinate; S3, introducing the detoxified wastewater into a struvite crystallization reactor, measuring the concentration and the volume of ammonia nitrogen in the wastewater, then adding magnesium chloride and potassium dihydrogen phosphate according to the ratio of (NH 4 + ):(Mg 2+ ):(PO 4 3- ) =1 (1.15-1.25): (1.05-1.15), regulating the pH value to 8.0-8.5, stirring and reacting for 20-40 min at 25-35 ℃, and filtering to obtain struvite crystals and high-nitrogen wastewater; And S4, introducing the high-nitrogen wastewater into a mesoporous silicon adsorption column modified by amino functionalization, adsorbing organic amine, performing adsorption saturation on the adsorption column, and then performing analysis by adopting a carbon dioxide saturated aqueous solution with the pH value of 5.3-5.7 to obtain an amine-containing analysis solution, introducing the amine-containing analysis solution into a stripping-absorbing unit, performing air stripping, and introducing a stripping gas flow into a 5-8wt% dilute sulfuric acid absorption tower to generate an ammonium salt solution taking dimethylamine sulfate and/or methylamine sulfate as main components.
  2. 2. The recycling method of the hexazinone production wastewater is characterized by further comprising the steps of S5, after the high-nitrogen wastewater in the step S4 is adsorbed by an adsorption column, generating denitrification wastewater, sending the deamination wastewater into a two-stage evaporation crystallizer, coating the inner wall of a heat exchange tube of the evaporator with a polytetrafluoroethylene anti-scaling coating, performing evaporation concentration to a solid-liquid ratio of 8-12% under normal pressure by using the waste heat of a rectifying tower kettle in the step S1, controlling the temperature of the wastewater to be 75-80 ℃, performing auxiliary heating by using low-pressure steam of 0.05-0.2 MPa, controlling the temperature of the wastewater to be 70-75 ℃, continuously concentrating to a solid-liquid ratio of 15-20% under normal pressure, and performing centrifugal separation on the concentrated solution to obtain industrial solid NaCl salt.
  3. 3. The recycling method of the hexazinone production wastewater according to claim 2 is characterized by further comprising the step S6 of centrifugally separating the concentrated solution in the step S5 to obtain industrial solid NaCl salt and concentrated mother liquor, regulating the pH of the concentrated mother liquor to 7.2-7.8, adding food-grade sodium citrate according to 0.1-0.3% of the mass of the concentrated mother liquor, adopting a program to cool to 20-25 ℃, standing and crystallizing for 10-14 h, and centrifugally obtaining high-purity sodium thiosulfate pentahydrate crystals.
  4. 4. The recycling method of the hexazinone production wastewater according to claim 3, wherein in the step S6, the programmed cooling is to keep the temperature at 45-55 ℃ for 5-15 minutes, then cool the temperature to 25-35 ℃ at a rate of 1.5-2.5 ℃ per hour, and cool the temperature to 20-25 ℃ at a rate of 0.8-1.2 ℃ per hour.
  5. 5. The recycling method of the hexazinone production wastewater according to claim 3 is characterized by further comprising the steps of S7, centrifuging concentrated mother liquor in the step S6 to obtain high-purity sodium thiosulfate pentahydrate crystals and crystallization mother liquor, introducing the crystallization mother liquor into an A/O-MBR biochemical tank, controlling an anaerobic section HRT at 7-9 h, degrading residual organic matters through denitrifying bacteria, controlling an aerobic section HRT at 15-17 h, intercepting high-efficiency microorganisms by an MBR membrane, controlling MLSS=3000-4000 mg/L, simultaneously adding 0.5g/L of powdery activated carbon for adsorption, precipitating, and separating solid from liquid to obtain supernatant.
  6. 6. The recycling method of the hexazinone production wastewater according to claim 1, wherein in the step S2, the mass ratio of the ferric oxide to the activated carbon is 1:2.5-3.5.
  7. 7. The recycling method of the wastewater from the production of the hexazinone according to claim 1, wherein in the step S2, the preparation method of the iron trioxide-activated carbon composite catalyst is as follows: Dissolving ferric nitrate nonahydrate in an ethanol-water mixed solution to prepare an impregnating solution with the concentration of 0.4-0.6 mol/L, adding coconut shell activated carbon, impregnating for 20-30 hours, adding APTES with the solid-liquid ratio of 1:9-11, continuously reacting for 3-5 hours, evaporating to remove a solvent to obtain a solid precursor, and finally roasting and activating the solid precursor, cooling, washing and drying to obtain the ferric oxide-activated carbon composite catalyst.
  8. 8. The recycling method of the hexazinone production wastewater according to claim 1, wherein in the step S4, the carbon dioxide saturated aqueous solution is dynamically prepared by introducing deionized water from industrial-grade CO 2 gas, the pH is precisely regulated and controlled to be 5.3-5.7, the analysis temperature is 25-35 ℃, the flow rate is 1.8-2.2 BV/h, the gas-liquid ratio of the air stripping is 600-750:1, and the temperature is 25-30 ℃.
  9. 9. The recycling method of the hexazinone production wastewater according to claim 1 is characterized in that in the step S4, the amine salt solution is conveyed to a selective catalytic reduction reactor of the step S2 through a metering pump to promote reaction in cooperation with sodium sulfite, and the blown-off CO 2 lean solution is returned to 5.3-5.7 through pH, and is recycled for preparing a new resolving agent.
  10. 10. The recycling method of the wastewater from the production of the hexazinone according to claim 1, wherein in the step S4, the preparation method of the modified mesoporous silicon modified by the amino functionalization is as follows: In the protection of nitrogen, mixing mesoporous silicon and toluene according to a solid-to-liquid ratio of 1:19-21, then heating to 75-85 ℃, dropwise adding AEAPMDS according to a ratio of AEAPMDS to mesoporous silicon with a mass ratio of 1:4-6, adding 0.05-0.1 mL glacial acetic acid as a catalyst after dropwise adding, carrying out reflux reaction for 10-14 h, cooling to room temperature after the reaction is finished, carrying out suction filtration, collecting a solid product, washing with absolute ethyl alcohol, and drying to obtain the modified mesoporous silicon modified by amino functionalization.

Description

Method for recycling wastewater from production of hexazinone Technical Field The invention belongs to the technical field of waste liquid recovery, and particularly relates to a method for recovering waste water from production of hexazinone. Background The hexazinone is a triazene herbicide developed by Dupont in 1974, has the characteristics of systemic selectivity, postemergence contact killing property, high efficiency and low toxicity, and becomes a first choice medicament for killing trees such as bamboo, shrubs, arbor and the like. However, wastewater is generated in the production process of the hexazinone, and if the wastewater is not completely recovered, the wastewater can cause environmental pollution and even threaten the health of human beings. At present, various published technologies are studied for treating and recycling the wastewater generated in the preparation of the hexazinone, and although the prior art achieves a certain effect in the treatment and recycling of the wastewater generated in the preparation of the hexazinone, the following defects still exist. (1) For example, the prior art adopts a distillation method to recover the methanol solvent in the wastewater, but the recovery efficiency is limited by azeotrope, the recovery cost of the low-concentration methanol wastewater (concentration is less than 5%) is higher, and the economical efficiency is not enough. Organic sulfur compounds in the wastewater are mainly oxidized and degraded, and recycling of sulfur resources is not realized. Methyl mercaptan as a byproduct needs to be treated by means of alkali absorption, which not only increases the amount of sulfur-containing wastewater produced, but also brings about environmental risks. The nitrogen source in amine-containing wastewater is typically recovered as low value ammonium sulfate and its potential value is underutilized. (2) The process integration level is insufficient, most of the disclosed technologies adopt sectional processing flows, the connection between units is poor, and the problems of high energy consumption, large occupied area and the like exist. For example, pretreatment, solvent recovery, biological treatment, etc. units are operated independently, and a co-optimized system is not formed, resulting in limited overall treatment efficiency. (3) The high-salinity wastewater is difficult to treat, the salinity in the hexazinone wastewater is high, the salinity which can be tolerated by the existing biological treatment process is limited, the microbial activity is inhibited under the high-salinity environment, the treatment effect is unstable, the energy consumption of the process for recovering the salinity by evaporation crystallization is high, the purity of the recovered salt is low, and the high-value utilization is difficult to realize. Disclosure of Invention Aiming at least one defect in the background art, the invention provides a recycling method of the wastewater generated in the production of the hexazinone, which has the characteristic of high recycling recovery rate. The aim of the invention can be achieved by the following technical scheme: a recycling method of the wastewater from the production of the hexazinone comprises the following steps: S1, introducing a hexazinone reaction mother liquor into a pressurized rectifying tower, adopting a high-efficiency stainless steel wire mesh as a filler material, controlling the operation pressure to be 0.3-0.5 MPa, the tower top temperature to be 78-82 ℃, the tower bottom temperature to be 85-90 ℃, the reflux ratio to be 1.2-1.8, the residence time to be 25-35 min, collecting methanol at the tower top, and the tower bottom to be the rectified residual liquid; S2, introducing the rectified residual liquid into a selective catalytic reduction reactor, regulating the pH to 6.5-7.5, heating to 35-45 ℃, adding an iron oxide-activated carbon composite catalyst and 25-35 wt% of sodium sulfite solution, wherein the adding amount of the iron oxide-activated carbon composite catalyst is 1.5-2.0% of the mass of the residual liquid, and the adding amount of the sodium sulfite solution is 3-5 kg/m 3 of the residual liquid; S3, introducing the detoxified wastewater into a struvite crystallization reactor, measuring the concentration and the volume of ammonia nitrogen in the wastewater, then adding magnesium chloride and potassium dihydrogen phosphate according to the ratio of (NH 4+):(Mg2+):(PO43-) =1 (1.15-1.25): (1.05-1.15), regulating the pH value to 8.0-8.5, stirring and reacting for 20-40 min at 25-35 ℃, and filtering to obtain struvite crystals and high-nitrogen wastewater; And S4, introducing the high-nitrogen wastewater into a mesoporous silicon adsorption column modified by amino functionalization, adsorbing organic amine, performing adsorption saturation on the adsorption column, and then performing analysis by adopting a carbon dioxide saturated aqueous solution with the pH value of 5.3-5.7 to obtain a