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CN-121972504-A - Low-temperature plasma-microbubble-based method and system for repairing composite organic pollutants in soil

CN121972504ACN 121972504 ACN121972504 ACN 121972504ACN-121972504-A

Abstract

The invention discloses a method and a system for repairing composite organic pollutants in soil based on low-temperature plasmas and microbubbles, wherein the repairing method is characterized in that a large number of microbubbles rich in active oxygen species are formed in a soil-water mixture formed after soil is added with water through controlling a plasma-microbubble reactor, an oxygen atmosphere, flow, current power, soil-water ratio and a catalyst, the mass transfer area of the active oxygen species between a gas phase, a water phase and a soil phase is enhanced through the microbubbles, the uniform distribution of the microbubbles in a device container is realized by combining with the precise control of mechanical stirring, the aim of fully contacting active oxygen species with a large amount of soil particles is fulfilled, the efficient mass transfer of the active oxygen species is realized, and the efficient repairing of a large amount of polluted soil is finished.

Inventors

  • SONG MIN
  • TANG DI
  • LIU ZONGHAO
  • JIA WENQIANG
  • FANG BIN
  • CHEN ZEQI
  • WANG SHAOFENG

Assignees

  • 东南大学

Dates

Publication Date
20260505
Application Date
20260211

Claims (10)

  1. 1. The method for repairing the composite organic pollutants in the soil based on the low-temperature plasma-micro bubbles is characterized by comprising the following steps of: (1) Preparing boron-nitrogen doped biochar by adopting a liquid phase impregnation method, mixing a nitrogen source precursor, a boron source precursor and glucose, adding the biochar, sequentially stirring, carrying out ultrasonic treatment, drying and carrying out pyrolysis reaction to obtain the boron-nitrogen doped biochar; (2) Pretreating organic contaminated soil to obtain a soil sample; (3) Mixing soil sample with water, adding into low temperature plasma-micro bubble reaction system, stirring, adding boron-nitrogen doped biochar, opening oxygen supply switch, regulating gas flowmeter, and repairing by electrifying reaction.
  2. 2. The method for repairing according to claim 1, wherein in the step (1), the biochar is prepared by washing biomass, drying in an oven at 70-105 ℃, placing in a tube furnace, heating to 600-800 ℃ in an atmosphere of N 2 at a rate of 8-10 ℃ per min, and maintaining for 3-4 hours.
  3. 3. The repairing method according to claim 1, wherein in the step (1), the nitrogen source precursor and the boron source precursor are urea and boric acid respectively, and the mass ratio of the nitrogen source precursor to the boron source precursor to the glucose to the biochar is 1:1:2-3:20.
  4. 4. The repair method according to claim 1, wherein in the step (1), the stirring time is 2-4 hours, the ultrasonic time is 2-4 hours, and the pyrolysis reaction is performed for 3-4 hours at a heating rate of 4-5 ℃ per minute under a nitrogen atmosphere at 700-800 ℃.
  5. 5. The method according to claim 1, wherein in the step (2), the pretreatment is to naturally dry the organic contaminated soil, remove impurities and grind the organic contaminated soil to obtain a soil sample.
  6. 6. The method for repairing a surface of a body of earth according to claim 1, wherein in the step (3), the mass ratio of soil to water is 1:4.5-5.5.
  7. 7. The repairing method according to claim 1, wherein in the step (3), the stirring speed is 800-1200r/min, the oxygen supply flow is 700-900mL/min, the power output of the energizing reaction is 70-90W, and the treatment time is 30-120min.
  8. 8. A system for use in the repair process of claim 1 wherein the system is a low temperature plasma-microbubble reaction system comprising a plasma-microbubble device, and an oxygen cylinder, a gas flow meter, a stirrer She Sulv controller, a high voltage power supply, and an oscilloscope connected thereto.
  9. 9. The system of claim 8, wherein the plasma-microbubble device body is a quartz barrel reactor with a flange cover sealed at the top, a coaxial cylindrical electrode is arranged on the flange cover, the lower end of the coaxial cylindrical electrode extends into the reactor, a microporous aeration head is arranged at the tail end of the electrode, the high-voltage electrode is connected with a power supply, the low-voltage electrode is grounded, the top of the electrode is connected with an air inlet, the flange cover is connected with an air outlet, and a gas flowmeter and an oscilloscope are further arranged.
  10. 10. The system of claim 9, wherein the coaxial cylindrical electrode is configured from inside to outside as a high voltage electrode, a ceramic dielectric surrounding the high voltage electrode, and a low voltage electrode, respectively, the ceramic dielectric and the low voltage electrode forming a gas chamber into which oxygen is supplied.

Description

Low-temperature plasma-microbubble-based method and system for repairing composite organic pollutants in soil Technical Field The invention relates to a method for repairing composite organic pollutants in soil, in particular to a method for repairing composite organic pollutants in soil based on low-temperature plasma-microbubbles, and also relates to a reaction system adopted by the method. Background At present, the main means for degrading organic pollutants in soil by using low-temperature plasma is to use a needle plate type and flat plate type dielectric barrier discharge device to perform discharge treatment on the polluted soil, or enrich the pollutants and catalyze the generation of active species by adding a catalyst on the basis, so that the utilization efficiency of active substances generated by the low-temperature plasma device is increased, and the purpose of efficiently degrading the pollutants is achieved. The main point of the route is that the polluted soil is subjected to low-temperature plasma treatment, namely, high-energy electrons are generated by applying an external electric field, molecules in gas entering the device are promoted to be ionized, active substances are generated above the soil, and then the active substances are transferred into the soil through a phase interface so as to act on pollutants. However, because the structural design of the plasma device and the method of using the same have the influence that the mass transfer distance of the active substances is severely affected by the thickness of the soil, when the soil to be repaired is thick, the active substances generated by the plasma device in the gas phase are difficult to penetrate the soil layer to contact and react with the pollutants and the catalyst, and the mass transfer and utilization rate of the active substances are limited, therefore, such a system can only repair thinner soil, the soil repair amount is lower, and because the active substances in the gas phase need a certain time to penetrate the soil layer, and most of the long-life active oxygen species leave the reaction system without fully reacting with the pollutants, thereby resulting in lower efficiency of the system for completing the whole repair process and longer time. In summary, the effect of separating and repairing soil pollutants in the practical application process is limited at present. Disclosure of Invention Aiming at the problems of small soil restoration amount, low efficiency, long time and limited practical application capacity caused by difficult mass transfer of active substances in the conventional low-temperature plasma technology when soil restoration is carried out, the invention aims to provide a restoration method of composite organic pollutants in soil based on low-temperature plasma-microbubbles, which is suitable for a large amount of soil and has extremely strong restoration effect, and also provides a reaction system adopted by the restoration method. The technical scheme is that the method for repairing the composite organic pollutants in the soil based on the low-temperature plasma-micro bubbles comprises the following steps: (1) Preparing boron-nitrogen doped biochar by adopting a liquid phase impregnation method, mixing a nitrogen source precursor, a boron source precursor and glucose, adding the biochar, sequentially stirring, carrying out ultrasonic treatment, drying and carrying out pyrolysis reaction to obtain the boron-nitrogen doped biochar; (2) Pretreating organic contaminated soil to obtain a soil sample; (3) Mixing soil sample with water, adding into low temperature plasma-micro bubble system, stirring, adding boron-nitrogen doped biochar, opening oxygen supply switch, regulating gas flowmeter, and repairing by electrifying reaction. In the step (1), the preparation method of the biochar comprises the steps of removing impurities from biomass, cleaning, drying in an oven at 70-105 ℃, placing in a tube furnace, heating to 600-800 ℃ in an N 2 atmosphere at a rate of 8-10 ℃ per minute, and keeping for 3-4 hours under the condition. In the step (1), the nitrogen source precursor and the boron source precursor are urea and boric acid respectively, and the mass-volume ratio of the nitrogen source precursor to the boron source precursor to the glucose to the biochar is 1:1:2-3:20. Wherein in the step (1), the stirring time is 2-4h, the ultrasonic time is 2-4h, and the pyrolysis reaction is carried out for 3-4h at the temperature of 700-800 ℃ under the heating rate of 4-5 ℃ per minute under the nitrogen atmosphere. In the step (2), the pretreatment is to naturally dry the organic polluted soil, remove impurities and grind the organic polluted soil to obtain a soil sample. In the step (3), the mass ratio of soil to water is 1:4.5-5.5. Wherein in the step (3), the stirring speed is 800-1200r/min, and the oxygen supply flow is 700-900mL/min. Wherein, in the step (3), the output power of the electrifying react