CN115365283A - Method for thermal desorption repair of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay - Google Patents
Method for thermal desorption repair of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay Download PDFInfo
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- 238000003795 desorption Methods 0.000 title claims abstract description 252
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- 230000008439 repair process Effects 0.000 title claims abstract description 77
- 238000000034 method Methods 0.000 title claims abstract description 41
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 77
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims abstract description 57
- 239000007788 liquid Substances 0.000 claims abstract description 8
- 239000011362 coarse particle Substances 0.000 claims abstract description 5
- 239000002245 particle Substances 0.000 claims abstract description 5
- 230000001681 protective effect Effects 0.000 claims abstract description 5
- GVEPBJHOBDJJJI-UHFFFAOYSA-N fluoranthene Chemical compound C1=CC(C2=CC=CC=C22)=C3C2=CC=CC3=C1 GVEPBJHOBDJJJI-UHFFFAOYSA-N 0.000 claims description 53
- 238000005067 remediation Methods 0.000 claims description 43
- MWPLVEDNUUSJAV-UHFFFAOYSA-N anthracene Chemical compound C1=CC=CC2=CC3=CC=CC=C3C=C21 MWPLVEDNUUSJAV-UHFFFAOYSA-N 0.000 claims description 36
- BBEAQIROQSPTKN-UHFFFAOYSA-N pyrene Chemical compound C1=CC=C2C=CC3=CC=CC4=CC=C1C2=C43 BBEAQIROQSPTKN-UHFFFAOYSA-N 0.000 claims description 30
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 claims description 22
- YNPNZTXNASCQKK-UHFFFAOYSA-N phenanthrene Chemical compound C1=CC=C2C3=CC=CC=C3C=CC2=C1 YNPNZTXNASCQKK-UHFFFAOYSA-N 0.000 claims description 22
- 125000005605 benzo group Chemical group 0.000 claims description 19
- NIHNNTQXNPWCJQ-UHFFFAOYSA-N fluorene Chemical compound C1=CC=C2CC3=CC=CC=C3C2=C1 NIHNNTQXNPWCJQ-UHFFFAOYSA-N 0.000 claims description 14
- 238000004108 freeze drying Methods 0.000 claims description 14
- 125000004054 acenaphthylenyl group Chemical group C1(=CC2=CC=CC3=CC=CC1=C23)* 0.000 claims description 11
- HXGDTGSAIMULJN-UHFFFAOYSA-N acetnaphthylene Natural products C1=CC(C=C2)=C3C2=CC=CC3=C1 HXGDTGSAIMULJN-UHFFFAOYSA-N 0.000 claims description 11
- DXBHBZVCASKNBY-UHFFFAOYSA-N 1,2-Benz(a)anthracene Chemical compound C1=CC=C2C3=CC4=CC=CC=C4C=C3C=CC2=C1 DXBHBZVCASKNBY-UHFFFAOYSA-N 0.000 claims description 6
- CFXWAPSYPXUYCO-UHFFFAOYSA-N ctk3e8812 Chemical compound C1=CC(C2)=C3C4=C5C2=CC=CC5=CC=C4C=CC3=C1 CFXWAPSYPXUYCO-UHFFFAOYSA-N 0.000 claims description 6
- FTOVXSOBNPWTSH-UHFFFAOYSA-N benzo[b]fluoranthene Chemical compound C12=CC=CC=C1C1=CC3=CC=CC=C3C3=C1C2=CC=C3 FTOVXSOBNPWTSH-UHFFFAOYSA-N 0.000 claims description 4
- 125000002080 perylenyl group Chemical group C1(=CC=C2C=CC=C3C4=CC=CC5=CC=CC(C1=C23)=C45)* 0.000 claims description 3
- CSHWQDPOILHKBI-UHFFFAOYSA-N peryrene Natural products C1=CC(C2=CC=CC=3C2=C2C=CC=3)=C3C2=CC=CC3=C1 CSHWQDPOILHKBI-UHFFFAOYSA-N 0.000 claims description 3
- LHRCREOYAASXPZ-UHFFFAOYSA-N dibenz[a,h]anthracene Chemical compound C1=CC=C2C(C=C3C=CC=4C(C3=C3)=CC=CC=4)=C3C=CC2=C1 LHRCREOYAASXPZ-UHFFFAOYSA-N 0.000 claims description 2
- 125000002029 aromatic hydrocarbon group Chemical group 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 69
- 239000002689 soil Substances 0.000 description 41
- 206010007269 Carcinogenicity Diseases 0.000 description 14
- 231100000260 carcinogenicity Toxicity 0.000 description 14
- 230000007670 carcinogenicity Effects 0.000 description 14
- 230000000711 cancerogenic effect Effects 0.000 description 11
- 231100000315 carcinogenic Toxicity 0.000 description 10
- 238000010276 construction Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 10
- 239000003344 environmental pollutant Substances 0.000 description 10
- RMBPEFMHABBEKP-UHFFFAOYSA-N fluorene Chemical compound C1=CC=C2C3=C[CH]C=CC3=CC2=C1 RMBPEFMHABBEKP-UHFFFAOYSA-N 0.000 description 10
- 231100000719 pollutant Toxicity 0.000 description 10
- 230000001988 toxicity Effects 0.000 description 10
- 231100000419 toxicity Toxicity 0.000 description 10
- 238000012216 screening Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 7
- 238000001035 drying Methods 0.000 description 6
- 238000010998 test method Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 238000003900 soil pollution Methods 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
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- 239000000126 substance Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000000944 Soxhlet extraction Methods 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000012502 risk assessment Methods 0.000 description 2
- 239000000741 silica gel Substances 0.000 description 2
- 229910002027 silica gel Inorganic materials 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 208000033962 Fontaine progeroid syndrome Diseases 0.000 description 1
- 208000032826 Ring chromosome 3 syndrome Diseases 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 150000001454 anthracenes Chemical class 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 238000002290 gas chromatography-mass spectrometry Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000002262 irrigation Effects 0.000 description 1
- 238000003973 irrigation Methods 0.000 description 1
- 229910052901 montmorillonite Inorganic materials 0.000 description 1
- 231100001223 noncarcinogenic Toxicity 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
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- 238000004062 sedimentation Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000005068 transpiration Effects 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/06—Reclamation of contaminated soil thermally
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
The application provides a method for thermal desorption and restoration of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay. The content of coarse particles with the particle size of more than 0.075mm in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is within 25 percent, and the liquid limit is higher than 50 percent; the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay at least comprises polycyclic aromatic hydrocarbons with 2-3 rings of aromatic hydrocarbon rings. The method comprises the following steps: performing thermal desorption repair on the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay under an inert protective atmosphere; the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is 0.01-15%, the thermal desorption restoration temperature is 250-450 ℃, and the thermal desorption restoration time is 20-40 min. The temperature for thermal desorption repair is 250-450 ℃, the time for thermal desorption repair is 20-40 min, and the total removal rate of polycyclic aromatic hydrocarbon with 2-3 rings of aromatic hydrocarbon in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay with the water content of 0.01-15% can be effectively removed by over 73%.
Description
Technical Field
The application relates to the technical field of soil remediation, in particular to a method for thermal desorption remediation of high-pollution and high-plasticity clay of polycyclic aromatic hydrocarbon.
Background
With the continuous acceleration of the industrialization process, the soil pollution is serious due to the unreasonable exploitation of mineral resources, smelting discharge of the mineral resources, sewage irrigation and sludge application to the soil for a long time, atmospheric sedimentation caused by artificial activities, application of chemical fertilizers and pesticides and the like. And the soil pollution has great harm to the soil for construction.
The soil pollution treatment method includes thermal desorption treatment and the like. However, in the related art, the thermal desorption treatment is not high enough in the overall removal rate of the polycyclic aromatic hydrocarbon pollutants and the like in the soil for buildings, and the removal effect is not good enough.
Disclosure of Invention
In view of this, an object of the present application is to provide a method for thermal desorption remediation of high-pollution and high-plasticity clay of polycyclic aromatic hydrocarbon.
Based on the purpose, the application provides a method for thermal desorption repair of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay, wherein the content of coarse particles with the particle size of more than 0.075mm in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is within 25%, and the liquid limit is higher than 50%; the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay at least comprises polycyclic aromatic hydrocarbons with 2-3 rings of aromatic hydrocarbon rings; the method comprises the following steps:
performing thermal desorption repair on the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay under inert protective atmosphere; the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is 0.01-15%, the thermal desorption restoration temperature is 250-450 ℃, and the thermal desorption restoration time is 20-40 min.
In some embodiments, the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is a clay subjected to freeze drying treatment, and the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay further comprises polycyclic aromatic hydrocarbons with 4-6 rings of aromatic hydrocarbon rings; the temperature of the thermal desorption repair is 350-450 ℃, and the time of the thermal desorption repair is 20-40 min.
In some embodiments, the temperature of the thermal desorption repair is 400-450 ℃, and the time of the thermal desorption repair is 20-40 min.
In some embodiments, the temperature of the thermal desorption repair is 400-450 ℃, and the time of the thermal desorption repair is 30min.
In some embodiments, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is 5-15%, the temperature of the thermal desorption repair is 350-450 ℃, and the time of the thermal desorption repair is 30min.
In some embodiments, the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay further comprises polycyclic aromatic hydrocarbons with 4-6 rings of aromatic hydrocarbon rings;
the temperature of the thermal desorption repair is 400-450 ℃, and the time of the thermal desorption repair is 30min.
In some embodiments, the temperature of the thermal desorption repair is 450 ℃, and the time of the thermal desorption repair is 30min.
In some embodiments, the 2-to 3-ring polycyclic aromatic hydrocarbon is selected from at least one of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene.
In some embodiments, the 4-6 ring polycyclic aromatic hydrocarbon is selected from benzo [ a ]]Anthracene,
Benzo [ b ]]Fluoranthene, benzo [ k ]]Fluoranthene, benzo [ a ]]Pyrene, benzo [1,2,3-cd]Pyrene, dibenzo [ a, h ]]Anthracene and benzo [ g, h, i ]]At least one perylene.
In some embodiments, the benzo [ a ] anthracene, benzo [ b ] fluoranthene, benzo [1,2,3-cd ] pyrene, and dibenzo [ a, h ] anthracene are present in amounts above standard.
From the above, according to the method for thermal desorption remediation of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay provided by the application, the temperature for thermal desorption remediation is 250-450 ℃, the time for thermal desorption remediation is 20-40 min, polycyclic aromatic hydrocarbons with 2-3 rings of aromatic hydrocarbon rings in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay with the water content of 0.01% -15% can be effectively removed, and the total removal rate is more than 73%.
Drawings
In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for the embodiments or related technologies in the following description are briefly introduced, and it is obvious that the drawings in the following description are only the embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a graph of the overall removal of 2-to 3-ring aromatics of example 2;
FIG. 2 is a graph showing the overall removal rate of aromatic hydrocarbons other than those having 2 to 3 rings of example 3;
FIG. 3 is a schematic diagram of the total removal rate of polycyclic aromatic hydrocarbons from the polycyclic aromatic hydrocarbon highly-polluted highly-plastic clay with water content in example 4;
FIG. 4 is a graph showing the effect of thermal desorption remediation on the toxicity equivalent of PAHs in highly contaminated and highly viscous soil of PAHs in example 5;
FIG. 5 is a graph showing the influence of thermal desorption remediation on the screening value of a land for construction, such as a land for use of PAHs in highly contaminated and highly viscous soil of PAHs in example 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to the accompanying drawings in combination with specific embodiments.
It should be noted that technical terms or scientific terms used in the embodiments of the present application should have a general meaning as understood by those having ordinary skill in the art to which the present application belongs, unless otherwise defined. The use of the terms "comprising" or "including" and the like in the embodiments of the present application, means that the element or item appearing before the term covers the element or item listed after the term and its equivalents, without excluding other elements or items.
The thermal desorption remediation method has the advantages of strong applicability, good remediation effect, simple process and the like, and is one of key technical means for remediation of the soil in the organic contaminated site. In the polycyclic aromatic hydrocarbon-contaminated clay, the polycyclic aromatic hydrocarbons may include polycyclic aromatic hydrocarbons with different ring numbers, such as polycyclic aromatic hydrocarbons with 2 to 3 rings and polycyclic aromatic hydrocarbons with 4 to 6 rings. In the related art, the thermal desorption repair process for the highly-polluted cohesive soil cannot perform good desorption on polycyclic aromatic hydrocarbons with different ring numbers and different water contents. Therefore, in the related art, the thermal desorption treatment of the polycyclic aromatic hydrocarbon pollutants in the polycyclic aromatic hydrocarbon highly-polluted and highly-plastic clay has the problem that the polycyclic aromatic hydrocarbons with different ring numbers and different water contents cannot be well desorbed.
Based on this, the embodiment of the application provides a method for polycyclic aromatic hydrocarbon high-pollution high-plasticity clay thermal desorption restoration, can solve to a certain extent and carry out good desorption to the polycyclic aromatic hydrocarbon of different moisture content of different ring numbers.
The embodiment of the application provides a method for polycyclic aromatic hydrocarbon high pollution high plasticity clay thermal desorption is restoreed, includes: performing thermal desorption repair on the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay under inert protective atmosphere; the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is 0.01-15%, the thermal desorption restoration temperature is 260-450 ℃, and the thermal desorption restoration time is 20-40 min. Wherein the polycyclic aromatic hydrocarbon at least comprises polycyclic aromatic hydrocarbon with 2-3 rings of aromatic hydrocarbon rings. The high-plasticity clay can be understood as high liquid limit clay, wherein the content of coarse particles with the particle size of more than 0.075mm is not higher than 25%, the content of montmorillonite minerals is high, and the liquid limit is higher than 50%, namely the content of the coarse particles with the particle size of more than 0.075mm in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is within 25% and the liquid limit is higher than 50%.
The method for thermal desorption repair of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay provided by the embodiment of the application has the advantages that the temperature for thermal desorption repair is 250-450 ℃, the time for thermal desorption repair is 20-40 min, polycyclic aromatic hydrocarbon with 2-3 rings of aromatic hydrocarbon rings in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay with the water content of 0.01% -15% can be effectively removed, and the total removal rate is more than 73%.
In some embodiments, the 2-to 3-ring polycyclic aromatic hydrocarbon may include any one of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene, or a combination of two or more thereof. That is, the 2-to 3-ring polycyclic aromatic hydrocarbon may be at least one selected from naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene.
In some embodiments, the polycyclic aromatic hydrocarbon highly-polluted high-plasticity clay is a clay after freeze-drying treatment, and the water content of the clay is close to 0, for example, the water content may be 0.001%. The temperature of the thermal desorption repair is 350-450 ℃, and the time of the thermal desorption repair is 20-40 min. Thus, the total removal rate of 2-to 3-ring polycyclic aromatic hydrocarbons can be 95% or more.
In some embodiments, the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is clay subjected to freeze drying treatment, and the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay further comprises polycyclic aromatic hydrocarbon with 4-6 rings of aromatic hydrocarbon rings. The temperature of the thermal desorption repair is 350-450 ℃, and the time of the thermal desorption repair is 20-40 min. Therefore, polycyclic aromatic hydrocarbons with 4-6 rings of aromatic hydrocarbon rings in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay are removed to a certain extent, the removal rate is more than 69%, and meanwhile, polycyclic aromatic hydrocarbons with 2-3 rings can be removed with the total removal rate of more than 95%. Meanwhile, the total removal rate of all polycyclic aromatic hydrocarbon is over 74 percent.
In some embodiments, the 4-6 ring polycyclic aromatic hydrocarbon may include benzo [ a ]]Anthracene,
Benzo [ b ]]Fluoranthene, benzo [ k ]]Fluoranthene, benzo [ a ]]Pyrene, benzo [1,2,3-cd]Pyrene, dibenzo [ a, h ]]Anthracene and benzo [ g, h, i ]]At least one perylene. Wherein, benzo [ a ]]Anthracene,
Benzo [ b ]]Fluoranthene, benzo [ k ]]Fluoranthene, benzo [ a ]]Pyrene, benzo [1,2,3-cd]Pyrene and dibenzo [ a, h ]]All anthracenes are carcinogenic. The temperature of thermal desorption restoration is 400-450 ℃, and the time of thermal desorption restoration is 20-40 min. The removal rate of polycyclic aromatic hydrocarbon with carcinogenicity can reach more than 80 percent, and the total removal rate of polycyclic aromatic hydrocarbon with 2-3 rings can reach more than 99 percent. The polycyclic aromatic hydrocarbon with 4-6 rings of aromatic hydrocarbon rings has the removal rate of over 86 percent. And meanwhile, the total removal rate of all polycyclic aromatic hydrocarbons is more than 89%.
In some embodiments, the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is clay subjected to freeze drying treatment, the thermal desorption restoration temperature is 400-450 ℃, and the thermal desorption restoration time is 30min. The removal rate of polycyclic aromatic hydrocarbon with carcinogenicity can reach more than 87 percent, and the total removal rate of polycyclic aromatic hydrocarbon with 2-3 rings can reach more than 99 percent. The polycyclic aromatic hydrocarbon with 4-6 rings of aromatic hydrocarbon ring number can lead the removal rate to reach more than 90 percent. Meanwhile, the total removal rate of all polycyclic aromatic hydrocarbons is over 91 percent.
In some embodiments, the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is a clay subjected to freeze drying treatment, the thermal desorption repairing temperature is 450 ℃, and the thermal desorption repairing time is 30min. The removal rate of polycyclic aromatic hydrocarbon with carcinogenicity can reach more than 98 percent, and the total removal rate of polycyclic aromatic hydrocarbon with 2-3 rings can reach more than 99 percent. The polycyclic aromatic hydrocarbon with 4-6 rings of aromatic hydrocarbon rings enables the removal rate to reach more than 99%. Meanwhile, the total removal rate of all polycyclic aromatic hydrocarbons is more than 99 percent.
In some embodiments, the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay may be clay after being dried, and the water content may be 5-15%. The temperature of the thermal desorption repair is 350-450 ℃, and the time of the thermal desorption repair is 30min. The total removal rate of 2-3 ring polycyclic aromatic hydrocarbon can be more than 96%. The polycyclic aromatic hydrocarbon with 4-6 rings of aromatic hydrocarbon rings enables the removal rate to reach more than 67 percent. The total removal rate of all polycyclic aromatic hydrocarbons can be more than 73%. The removal rate of polycyclic aromatic hydrocarbon with carcinogenicity can reach more than 62 percent.
In some embodiments, the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay can be clay after being dried, the temperature of the thermal desorption repair is 400-450 ℃, and the time of the thermal desorption repair is 30min. The total removal rate of 2-3 ring polycyclic aromatic hydrocarbon can be more than 99 percent. The polycyclic aromatic hydrocarbon with 4-6 rings of aromatic hydrocarbon rings has the removal rate of over 84 percent. The total removal rate of all polycyclic aromatic hydrocarbons can be more than 87%. The removal rate of polycyclic aromatic hydrocarbon with carcinogenicity can reach more than 80%.
In some embodiments, the polycyclic aromatic hydrocarbon highly-polluted high-plasticity clay can be clay after being dried, the temperature of thermal desorption repair is 450 ℃, and the time of thermal desorption repair is 30min. The total removal rate of 2-3 ring polycyclic aromatic hydrocarbon can be more than 99 percent. The polycyclic aromatic hydrocarbon with 4-6 rings of aromatic hydrocarbon ring number can lead the removal rate to reach more than 98 percent. The total removal rate of all polycyclic aromatic hydrocarbons is more than 98 percent. The removal rate of polycyclic aromatic hydrocarbon with carcinogenicity can reach more than 98 percent. Therefore, the removal rate of more than 98 percent can be realized without completely drying the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay, and energy can be saved.
Namely, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is 0.01-15%, the thermal desorption repairing temperature is 450 ℃, the thermal desorption repairing time is 30min, and the removal rate can reach more than 98%.
In some embodiments, the inert protective atmosphere may be nitrogen. In the thermal desorption repair process, the input amount can be 0.3L/min.
The technical solution of the present invention will be further described with reference to the following embodiments.
The experimental procedures in the following examples are conventional unless otherwise specified.
The test materials used in the following examples were purchased from conventional chemical stores unless otherwise specified.
Example 1 soil plasticity analysis and pollutant component analysis of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay
Test materials: polycyclic aromatic hydrocarbons contaminate clay. Wherein the polycyclic aromatic hydrocarbon polluted clay is taken from a polluted site of a certain chemical plant in Hunan Tan City in Hunan province.
The test method comprises the following steps:
and (3) soil plasticity analysis: soil plasticity analysis was performed according to the road soil test protocol (JTG 3430-2020).
And (3) analyzing the components of the pollutants: soxhlet extraction of residual polycyclic aromatic hydrocarbons in soil is carried out with reference to HJ 805-2016 soil and sediment, determination of polycyclic aromatic hydrocarbons, gas chromatography-mass spectrometry, USEPA METHOD 3540C (Soxhlet extraction); concentrating the extractive solution with rotary evaporator and nitrogen blowing instrument; purification was performed using a silica gel column with reference to USEPA METHOD 3630C (silica gel column purification); and PAHs were quantitatively analyzed using Shimadzu GCMS-QP2010 plus. The concrete conditions are as follows: the temperature of the injector, interface and ion source were all 300 ℃. The column oven was initially 60 deg.C, ramped up to 250 deg.C at a rate of 10 deg.C/min and held at temperature for 3 minutes, then ramped up to 290 deg.C at a rate of 4 deg.C/min and held at temperature for 5 minutes.
And (3) test results:
the liquid limit, plastic limit and plasticity index of the polycyclic aromatic hydrocarbon polluted clay are respectively 56%, 24% and 31, and the organic matter content is 3.4g/kg.
In the polycyclic aromatic hydrocarbon polluted clay, 16 polycyclic aromatic hydrocarbon pollutants exist. The total contaminant concentration therein was 212.3mg/kg (RSD = 1.17%), and the specific ingredients and specific concentrations of the respective ingredients are shown in table 1.
TABLE 1 polycyclic aromatic hydrocarbons in PAHs contaminated Clays
And (4) analyzing results: according to the highway geotechnical test code (JTG 3430-2020), the polycyclic aromatic hydrocarbon-contaminated clay is a high liquid limit clay, i.e., a high plasticity clay. The pollution concentrations of the pollutants BaA, bbF, IPY and DBA are higher than the screening value of the pollution of construction land and other lands, and are respectively 3.3 times, 4.0 times, 3.8 times and 39.9 times of the screening value, and the pollutants are high-pollution clay. Therefore, the test material belongs to polycyclic aromatic hydrocarbon high-pollution high-plasticity clay.
Example 2 influence of thermal desorption temperature and thermal desorption duration on removal rate of polycyclic aromatic hydrocarbons of 2-3 rings of freeze-dried polycyclic aromatic hydrocarbon highly-polluted highly-plastic clay
Test materials: the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay subjected to freeze drying treatment is about 0.01 percent and is close to 0 percent.
And (3) test groups:
Test group 2, the temperature for thermal desorption repair is 350 ℃. Including test group 2-1, the thermal desorption duration was 20min. The thermal desorption time of the test groups 2-2 is 30min. The thermal desorption time of the experimental groups 2-3 is 40min.
Test group 3, temperature for thermal desorption repair 400 ℃. Comprises a test group 3-1, and the thermal desorption time is 20min. The thermal desorption time of the test groups 3-2 is 30min. The thermal desorption time of the test groups 3-3 is 40min.
The test method comprises the following steps: raising the temperature under the continuously introduced nitrogen gas of 0.1L/min, quickly pushing a porcelain boat filled with the polluted clay after stabilizing to a target temperature (thermal desorption restoration temperature), carrying out thermal desorption treatment for a target heat preservation time (thermal desorption restoration duration) under the continuously introduced nitrogen gas atmosphere of 0.3L/min, and cooling along with the furnace in the continuously introduced nitrogen gas after the thermal desorption is finished. After cooling, the components were measured by the method for measuring the components and concentrations as in example 1, and the removal rate of the specific components was obtained.
The experimental results are as follows: the results of the overall removal rate of 2-to 3-ring aromatic hydrocarbons of example 2 are shown in table 2 and fig. 1.
TABLE 2 Overall removal Rate results for Ring-3 aromatics
As can be seen from Table 2, for the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay subjected to freeze drying treatment, when the thermal desorption repair temperature is 250-450 ℃ and the thermal desorption repair time is 20-40 min, the total removal rate of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene can reach more than 72%.
Further, when the temperature of thermal desorption repair is 350-450 ℃ and the time of thermal desorption repair is 20-40 min, the total removal rate of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene can reach more than 95%.
Further, when the temperature of thermal desorption repair is 400-450 ℃ and the time of thermal desorption repair is 20-40 min, the total removal rate of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene can reach more than 98.8%. The thermal desorption repair method disclosed by the embodiment of the application has a good overall removal rate for 2-3 rings of aromatic hydrocarbon in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay after freeze drying treatment.
Example 3 influence of thermal desorption temperature and thermal desorption duration on total removal rate of 4-6-ring polycyclic aromatic hydrocarbon and total polycyclic aromatic hydrocarbon in freeze-dried polycyclic aromatic hydrocarbon highly-polluted high-plasticity clay
Test materials: the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay subjected to freeze drying treatment is about 0.01 percent and is close to 0 percent.
And (3) test groups:
test group 8, temperature for thermal desorption remediation 350 ℃. Comprises a test group 8-1, and the thermal desorption time is 20min. In the test group 8-2, the thermal desorption time is 30min. The thermal desorption time of the test groups is 40min to 8-3.
Test group 9, temperature for thermal desorption remediation 400 ℃. Including test group 9-1, the thermal desorption duration was 20min. For the test group 9-2, the thermal desorption time is 30min. The thermal desorption time of the test groups 9-3 is 40min.
The test method comprises the following steps: same as in example 2.
Comparative example 1
The difference from example 3 is only that the test group is control group 1, and the temperature of thermal desorption repair is 250 ℃. Including control group 1-1, and the thermal desorption time is 20min. For the control group 1-2, the thermal desorption time was 30min. For the control groups 1-3, the thermal desorption time was 40min.
The overall removal rate of the 4-6 ring polycyclic aromatic hydrocarbons and the overall removal rate of the total polycyclic aromatic hydrocarbons in example 3 and comparative example 2 are shown in table 3, fig. 1 and fig. 2.
As shown in fig. 2, at a certain temperature, the thermal desorption of the polycyclic aromatic hydrocarbon has certain plateaus, that is, the total removal rate is basically kept unchanged as the thermal desorption time increases after a certain time. The higher the temperature, the earlier the plateau stage, for example, the thermal desorption treatment at 350 ℃ is performed, the total removal rate of 30min and 40min thermal desorption is basically consistent, while the total removal rate of 16PAHs is not greatly affected by the time increase of 20min-40min when the thermal desorption treatment at 400 ℃ and 450 ℃ is performed.
After the carcinogenic polycyclic aromatic hydrocarbon (Carci-PAHs) is thermally desorbed at different temperatures and time, the residual quantity change trend of the carcinogenic polycyclic aromatic hydrocarbon (Carci-PAHs) in soil has certain similarity with 16 PAHs. However, the residual content of non-carcinogenic polycyclic aromatic hydrocarbon in the soil becomes smaller and smaller with the rising temperature, especially the temperature of 400 ℃, and at 450 ℃, the polycyclic aromatic hydrocarbon remained in the soil is almost all the polycyclic aromatic hydrocarbon with carcinogenic effect.
As shown in figure 1, the initial concentration of 2-3 rings of polycyclic aromatic hydrocarbon in clay is 42.7mg/kg, and the initial concentration of 4-6 rings is 169.6mg/kg. The thermal desorption treatment at 250 ℃ can ensure that the overall removal rate of 2-3-ring PAHs reaches 72.02-82.58%, and the overall removal rate of 4-6-ring PAHs is only 33.59-44.25% under the same conditions. The thermal desorption treatment at 400 ℃ for 30min can ensure that the total removal rate of 2-3-ring polycyclic aromatic hydrocarbon reaches more than 99 percent and is 99.12 percent, but the thermal desorption temperature needs to be increased to 450 ℃ when the total removal rate of 4-6-ring polycyclic aromatic hydrocarbon reaches more than 99 percent.
Taking 90% of the total removal rate as a critical line, for tetracyclic PAHs, bbF can be achieved only by thermal desorption treatment at 450 ℃ for 20min, and the isomer BkF can be achieved only by thermal desorption treatment at 400 ℃ for 30 min; the total removal rate of FLU and CHR with boiling point and relative molecular mass of 384 ℃, 202, 448 ℃ and 228 respectively reaches more than 90 percent after thermal desorption treatment at 400 ℃ for 20min, and PYR and BaA with boiling point and relative molecular mass of 404 ℃, 202, 475 ℃ and 228 respectively reach after thermal desorption at 350 ℃ for 20min and 350 ℃ for 30min.
TABLE 3 Total removal of Total polycyclic aromatic hydrocarbons and Total polycyclic aromatic hydrocarbons results
As can be seen from table 3, in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay subjected to freeze drying treatment, in test groups 8, 9 and 10 in example 3, when the temperature of thermal desorption repair is 350 to 450 ℃ and the time of thermal desorption repair is 20 to 40min, the total removal rate of aromatic hydrocarbons with 4 to 6 rings can reach 69% or more, the total removal rate of aromatic hydrocarbons with carcinogenicity can reach 65% or more, and the total removal rate of all aromatic hydrocarbons can reach 74% or more. All had only a 30% improvement compared to control 1. It is indicated that the suitable thermal desorption temperature is different for the aromatic hydrocarbon pollutants with different ring numbers, is suitable for the thermal desorption temperature of the aromatic hydrocarbon pollutants with 2-3 rings, and is not suitable for the aromatic hydrocarbon pollutants with 4-6 rings.
Further, when the temperature of thermal desorption repair is 400-450 ℃, and the time of thermal desorption repair is 20-40 min, the total removal rate of aromatic hydrocarbons with 4-6 rings can reach more than 86%, the total removal rate of aromatic hydrocarbons with carcinogenicity can reach more than 83%, and the total removal rate of all aromatic hydrocarbons can reach more than 89%.
Further, when the temperature of thermal desorption repair is 400-450 ℃ and the time of thermal desorption repair is 30min, the total removal rate of aromatic hydrocarbons with 4-6 rings can reach more than 90%, the total removal rate of aromatic hydrocarbons with carcinogenicity can reach more than 87%, and the total removal rate of all aromatic hydrocarbons can reach more than 91%.
Further, when the temperature of thermal desorption repair is 450 ℃ and the time of thermal desorption repair is 20-40 min, the total removal rate of aromatic hydrocarbons with 4-6 rings can reach more than 97%, the total removal rate of aromatic hydrocarbons with carcinogenicity can reach more than 96%, and the total removal rate of all aromatic hydrocarbons can reach more than 97%. The thermal desorption repair method disclosed by the embodiment of the application has a good overall removal rate for the overall removal rates of 4-6-ring aromatic hydrocarbons, carcinogenic aromatic hydrocarbons and all aromatic hydrocarbons in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay.
Example 4 Effect of Water content on Total removal Rate of polycyclic aromatic hydrocarbons from highly contaminated highly Plastic Clay of polycyclic aromatic hydrocarbons
Test materials: the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay subjected to freeze drying treatment is about 0.01 percent and is close to 0 percent. The water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay after drying treatment is 5%. The water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay after drying treatment is about 10 percent. The water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay after drying treatment is about 15%.
And (3) test groups:
in test group 5, the temperature for thermal desorption repair is 350 ℃, and the thermal desorption time is 30min. Comprises a test group 5-1, and the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 0.01 percent. And in the test group 5-2, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 5 percent. In test groups 5-3, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 10%. And 5-4, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 15%.
In test group 6, the temperature for thermal desorption repair is 400 ℃, and the thermal desorption time is 30min. The method comprises a test group 6-1, wherein the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 0.01%. Test group 6-2, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 5%. And in test group 6-3, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 10%. In test group 6-4, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 15%.
In test group 7, the temperature for thermal desorption repair is 450 ℃, and the thermal desorption time is 30min. The method comprises a test group 7-1, wherein the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 0.01%. In test group 7-2, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 5%. 7-3 of test group, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 10%. 7-4 of test group, the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is about 15%.
The test method comprises the following steps: the same as in example 2.
And (3) test results: as shown in table 4 and fig. 3.
As is apparent from FIGS. 3 and 4, 2-to 3-ring PAHs are each subjected to 5% to 15% by weight at 350 to 400 ℃ in such a manner that the thermal desorption efficiency of 2-to 3-ring tends to increase as the water content increases. Water content, 15% wt. water content contaminated clay the residual 2-3 ring PAHs in the soil was reduced from 3.32% to 2.97% by 0.35% by thermal desorption at 350 ℃ for 30 min; after thermal desorption at 400 ℃ for 30min, the residual 2-3 ring PAHs in the clay is reduced from 0.87% to 0.43%. Therefore, for clay mainly contaminated with 2-to 3-ring PAHs, the water content was controlled to 10% by weight to 15% by weight at the time of thermal desorption remediation. At the moment, the thermal desorption repair of the dry soil can achieve similar (350 ℃) or better (400 ℃ and 450 ℃) removal effect. When the water content control method is used, the total removal rate of 2-3 ring PAHs can reach more than 99% by thermal desorption at 400 ℃ for 30min, and ACY, ANA and FLU are completely removed; the effect of continuously increasing the temperature on improving the thermal desorption efficiency of the 2-3 rings is weaker. Therefore, when the temperature is 400 ℃ for 30min, compared with the dry soil, the residual concentration of 2-3 ring PAHs is reduced from 0.80 percent to 0.73-0.43 percent.
For 4-6 ring PAHs, the thermal desorption efficiency of 4-6 ring PAHs shows a tendency of first increasing and then decreasing with the increase of the water content at the thermal desorption temperature of 350-450 ℃, which is reached when 10% by weight. Therefore, for clay mainly polluted by 4-6-ring PAHs, the water content is controlled to be 0-10 wt% during thermal desorption remediation. When the water content control method is used, baP can be completely removed through thermal desorption restoration at 450 ℃ for 30min, and the total removal rate of 4-6 ring PAHs is higher than 99%. The water contents of 5% by weight and 10% by weight have a certain promotion effect on desorption of PAHs contaminated cohesive soil compared with dry soil, and the total residue of 4-6 rings of PAHs is reduced from 0.99% to 0.92% and 0.76%. Therefore, the water content was further screened to 10% by weight at 450 ℃ for 30min. In this case, the residual concentration of 2-3 ring PAHs is reduced from 0.99 to 0.76% compared with that of dry soil.
TABLE 4 influence of Water content on Total removal Rate of polycyclic aromatic hydrocarbons from highly contaminated highly plastic Clay of polycyclic aromatic hydrocarbons
For the 16PAHs which are optimally controlled by EPA, when the thermal desorption temperature is 350-400 ℃, the water content within 10 percent by weight does not cause great influence on the thermal desorption efficiency. 5% wt. the water content causes a small decrease in thermal desorption efficiency, and the thermal desorption efficiency at 350 ℃ and 400 ℃ decreases by 4.37% and 1.61%, respectively. When PAHs contaminated clay is thermally desorbed at 350 ℃, the water content of 10% by weight is increased to 5% by weight, and the thermal desorption efficiency is improved by 1.88%, but is still slightly lower than that of the thermal desorption efficiency without water. When PAHs contaminated soil is thermally desorbed using 400 ℃, the thermal desorption efficiency of 10% wt. water content is equivalent to 5% wt. basically, and the thermal desorption efficiency is significantly reduced by 15% wt. water content. Compared with the method without adding water, the thermal desorption efficiency at 350 ℃ and 400 ℃ is respectively reduced by 6.95 percent and 4.23 percent. Whereas experiments on the effect of a water content of 450 ℃ for 30min on thermal desorption efficiency showed that a water content of 5% wt. and 10% wt. has a certain promoting effect on desorption of viscous soil contaminated with PAHs, the total residue of EPA-optimized 16PAHs was reduced from 0.84% to 0.75% and 0.62%, and the total residue of carcinogenic PAHs was reduced from 1.17% to 1.11% and 0.91%. Therefore, the moisture content was screened to 10% wt, the thermal desorption temperature and time was screened to: 30min at 450 ℃. At this time, the thermal desorption efficiency can be more than 99%, and the toxicity represented by TEQs is only within 1% of the polluted clay before restoration. When the PAHs are subjected to high-temperature thermal desorption treatment at 450 ℃, residual PAHs which are difficult to desorb originally are further removed due to the participation of water. This indicates that at a thermal desorption temperature of 450 ℃, a suitable water-contaminated clay feed ratio can improve the thermal desorption remediation efficiency of the soil.
As can be seen from Table 4, for the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay with different water contents, when the water content is 0.01-15%, the thermal desorption repair temperature is 350-450 ℃, and the thermal desorption repair time is 30min, the total removal rate of 4-6-ring aromatic hydrocarbon can reach above 71%. The total removal rate of the aromatic hydrocarbon with carcinogenicity can reach more than 62 percent, and the total removal rate of all the aromatic hydrocarbon can reach more than 73 percent. And the total removal rate of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene can reach more than 96%. It is stated that the suitable thermal desorption temperatures are not the same for aromatics of different ring numbers.
Further, for the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay with different water contents, when the water content is 0.01-15%, the thermal desorption repairing temperature is 400-450 ℃, and the thermal desorption repairing time is 30min, the total removal rate of 4-6-ring aromatic hydrocarbon can reach over 84%. The total removal rate of the aromatic hydrocarbon with carcinogenicity can reach more than 80 percent, and the total removal rate of all the aromatic hydrocarbon can reach more than 87 percent. And the total removal rate of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene can reach more than 99%. Wherein, when the water content is 10-15%, the total removal rate of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene can be further improved. It can be seen that for thermal desorption at a temperature of 400 to 450 ℃, the influence of different water contents on the overall removal rate of polycyclic aromatic hydrocarbons with different ring numbers is different. For polycyclic aromatic hydrocarbons with 2-3 rings, the water content is set to 10-15% as the water content is not higher or lower, and the reduction of heat transportation in the thermal desorption repair process of polluted cohesive soil caused by the caking property of clay to thermal desorption equipment and the agglomeration of the cohesive soil due to too high water content can be avoided; but also can generate certain promotion effect on thermal desorption through the transpiration of moisture and OH free radicals in water excited by high temperature or microwave radiation.
Further, for the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay with different water contents, when the water content is 0.01-15%, the thermal desorption repairing temperature is 450 ℃, and the thermal desorption repairing time is 30min, the total removal rate of the 4-6-ring aromatic hydrocarbon can reach more than 98%. The total removal rate of the aromatic hydrocarbon with carcinogenicity can reach more than 98 percent, and the total removal rate of all the aromatic hydrocarbon can reach more than 98 percent. And the total removal rate of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene can reach more than 99.89%. When the water content is 5-15%, the thermal desorption repair efficiency can be increased compared with that of 0%, the total removal rate of 4-6 ring aromatics, the total removal rate of carcinogenic aromatics and the total removal rate of all aromatics can be further improved, and the total removal rate of 2-3 ring aromatics is improved to be close to 99%.
Further, for the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay with different water contents, when the water content is 10%, the thermal desorption repairing temperature is 450 ℃, and the thermal desorption repairing time is 30min, the thermal desorption efficiency can be further improved, the total removal rate of 2-3 rings of aromatic hydrocarbon can reach more than 99.9%, and the total removal rate of 4-6 rings of aromatic hydrocarbon can reach more than 99%. The total removal rate of the aromatic hydrocarbon with carcinogenicity can reach more than 99 percent, and the total removal rate of all the aromatic hydrocarbon can reach more than 99 percent. The thermal desorption repair method disclosed by the embodiment of the application has a good overall removal rate for 2-3 ring aromatic hydrocarbons, 4-6 ring aromatic hydrocarbons, carcinogenic aromatic hydrocarbons and all aromatic hydrocarbons in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay with different water contents.
Combined with TEQ, carcinogenic risk analysis, the water content was controlled to 10% wt., with the highest overall removal rate for thermal desorption repair at 450 ℃ for 30min. On the basis, if the DBA concentration is lower, 400 ℃ can be selected for 40min. For 2-3 rings of PAHs, the water content was controlled to 10-15% wt, the overall removal rate of thermal desorption repair at 400 ℃ for 30min was highest; for 4-6 ring PAHs, the water content was controlled to 10% by weight, and the total removal rate of thermal desorption repair was the highest at 450 ℃ for 30min. Thus, the pretreatment of wet clay will not require pre-drying to near full dryness, drying to 10% wt.
Example 5 influence of thermal desorption remediation on toxicity equivalents of PAHs in highly contaminated highly viscous soils with PAHs
Toxicity equivalent principle: the use of Toxicity Equivalent Factor (TEF) is one method of soil risk assessment. The toxicity of polycyclic aromatic hydrocarbon mixed pollution in soil in the method can be expressed as a single number, and replaced by equivalent concentration of most toxic or carcinogenic homologues (TEQ). PAH, which is generally considered to be the most toxic and carcinogenic, is used: the equivalent concentration of BaP is used as the toxicity equivalent TEQ of residual polycyclic aromatic hydrocarbon after thermal desorption of the viscous soil.
Test materials: the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay subjected to freeze drying treatment is about 0.01 percent and is close to 0 percent.
And (3) test groups: test group 11, temperature for thermal desorption remediation 450 ℃. Including test group 11-1, the thermal desorption duration was 30min. For test group 11-2, the thermal desorption time was 40min.
For control 2, the temperature for thermal desorption repair was 250 ℃. Including control group 2-1, the thermal desorption time is 20min. For the control group 2-2, the thermal desorption time was 30min. For the control groups 2-3, the thermal desorption time was 40min.
In the control group 3, the temperature for thermal desorption repair is 350 ℃. Including a control group 3-1, and the thermal desorption time is 20min. For the control group 3-2, the thermal desorption time was 30min. For the control group 3-3, the thermal desorption time was 40min.
Control 4, temperature for thermal desorption repair 400 ℃. The control group is included 4-1, and the thermal desorption time is 20min. For the control group 4-2, the thermal desorption time was 30min. For the control group 4-3, the thermal desorption time was 40min.
The temperature for thermal desorption repair was 450 ℃ for control group 5. For the control group 5-1, the thermal desorption time was 20min.
The test method comprises the following steps: the same as in example 2.
And (3) test results: as shown in table 5 and fig. 4.
TABLE 5 influence of thermal desorption remediation on the toxicity equivalent of PAHs in highly contaminated and highly viscous soils with PAHs
And (4) analyzing results:
as shown in fig. 4, generally, the toxicity equivalent TEQ of the soil residual PAHs after thermal desorption tends to decrease with increasing temperature at the same time, and the TEQ tends to decrease with increasing temperature at the same time. However, at a temperature of 350 ℃, the thermal desorption time increased from 30min to 40min did not cause a significant decrease in TEQ. The thermal desorption efficiency has the same rule, and the decisive factor of the temperature is larger than that of the time, for example, the TEQ of clay residual PAHs is certainly lower than 250 ℃ for 20-40 min after the thermal desorption treatment at 350 ℃ for 20 min; after the thermal desorption treatment at 400 ℃ for 20min, the TEQ of clay residual PAHs is lower than 350 ℃ for 20-40 min, and the like. The thermal desorption treatment is carried out at the temperature of 450 ℃ for 30min, so that the TEQ of the residual PAHs is reduced to 0.45mg/kg, which is lower than the risk screening value of BaP in soil pollution of land such as construction land.
As can be seen from FIG. 3 and Table 5, the toxicity equivalent TEQ of test group 11-1 and test group 11-2 was lower than that of the soil of the first class of construction sites, compared with control group 2 to control group 5. It can be seen that the thermal desorption restoration conditions of the test group 11-1 and the test group 11-2 can make the PAHs highly-polluted highly-viscous soil meet the screening value of the soil of the construction land class after thermal desorption restoration.
Example 6 influence of thermal Desorption remediation on screening value of land for construction land such as PAHs in highly contaminated highly viscous soil of PAHs
Test materials: the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay subjected to freeze drying treatment is about 0.01 percent and is close to 0 percent.
And (3) test groups: in the test group 12, the temperature for thermal desorption repair is 450 ℃, and the thermal desorption time is 30min.
In the control group 6, the temperature for thermal desorption repair is 350 ℃, and the thermal desorption time is 30min.
In the control group 7, the temperature for thermal desorption repair is 400 ℃, and the thermal desorption time is 30min.
The test method comprises the following steps: the same as in example 2.
And (3) test results: as shown in table 6 and fig. 5.
TABLE 6 influence of thermal desorption remediation on screening value of construction land for PAHs in PAHs highly polluted highly viscous soil
As can be seen from table 6 and fig. 5, the overall removal rate of DBA was improved by 26% and 37% for the test group 12 compared to the control group 6 and the control group 7, respectively. All contaminants in test group 12 reached the construction field class soil screening value. Therefore, the thermal desorption remediation process parameters in the test group 12, namely 30min at 450 ℃, can enable the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay to reach the screening value of the soil such as construction land after thermal desorption remediation.
The application embodiment provides a be used for prosthetic moisture content control of polycyclic aromatic hydrocarbon high pollution high plasticity clay thermal desorption and processing method, before polluting high stickness clay to PAHs and carry out thermal desorption to restore, the stoving step of going on need not to dry to the full, and corresponding moisture content control is carried out to the ring number of the arene of desorption as required, can obtain good thermal desorption repair efficiency, has highlighted the prosthetic technical advantage of thermal desorption.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the present disclosure, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of brevity.
While the present disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description.
The disclosed embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalents, improvements, and the like that may be made within the spirit and principles of the embodiments of the disclosure are intended to be included within the scope of the disclosure.
Claims (10)
1. The thermal desorption remediation method for the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is characterized in that the content of coarse particles with the particle size of more than 0.075mm in the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is within 25% and the liquid limit is higher than 50%; the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay at least comprises polycyclic aromatic hydrocarbons with 2-3 rings of aromatic hydrocarbon rings; the method comprises the following steps:
performing thermal desorption repair on the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay under an inert protective atmosphere; the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is 0.01-15%, the thermal desorption restoration temperature is 250-450 ℃, and the thermal desorption restoration time is 20-40 min.
2. The method for thermal desorption remediation of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay according to claim 1, wherein the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is a clay subjected to freeze drying treatment, and the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay further comprises polycyclic aromatic hydrocarbons with 4-6 rings of aromatic hydrocarbon rings; the temperature of the thermal desorption repair is 350-450 ℃, and the time of the thermal desorption repair is 20-40 min.
3. The method for thermal desorption remediation of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay according to claim 2, wherein the temperature of the thermal desorption remediation is 400-450 ℃, and the time of the thermal desorption remediation is 20-40 min.
4. The method for thermal desorption remediation of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay according to claim 3, wherein the temperature of the thermal desorption remediation is 400-450 ℃, and the time of the thermal desorption remediation is 30min.
5. The method for thermal desorption remediation of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay according to claim 1, wherein the water content of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay is 5-15%, the temperature of the thermal desorption remediation is 350-450 ℃, and the time of the thermal desorption remediation is 30min.
6. The method for thermal desorption remediation of the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay according to claim 5, wherein the polycyclic aromatic hydrocarbon high-pollution high-plasticity clay further comprises polycyclic aromatic hydrocarbons with 4-6 rings of aromatic hydrocarbon rings;
the temperature of thermal desorption restoration is 400-450 ℃, and the time of thermal desorption restoration is 30min.
7. The method for thermal desorption remediation of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay according to claim 6, wherein the temperature of the thermal desorption remediation is 450 ℃, and the time of the thermal desorption remediation is 30min.
8. The method for thermal desorption remediation of the highly-polluted and highly-plastic clay containing polycyclic aromatic hydrocarbons as claimed in claim 1, wherein the 2-3 ring polycyclic aromatic hydrocarbons are selected from at least one of naphthalene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene.
9. The method for thermal desorption remediation of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay according to claim 2 or 6, wherein the polycyclic aromatic hydrocarbon with 4-6 rings is selected from benzo [ a ]]Anthracene,
Benzo [ b ]]Fluoranthene, benzo [ k ]]Fluoranthene, benzo [ a ]]Pyrene, benzo [1,2,3-cd]Pyrene, dibenzo [ a, h ]]Anthracene and benzo [ g, h, i ]]At least one perylene.
10. The method for thermal desorption remediation of polycyclic aromatic hydrocarbon high-pollution high-plasticity clay according to claim 9, wherein the contents of benzo [ a ] anthracene, benzo [ b ] fluoranthene, benzo [1,2,3-cd ] pyrene and dibenzo [ a, h ] anthracene are all higher than a standard value.
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