A method of monitoring the remediation of contaminated soil

Abstract

The application provides a method for monitoring a contaminated soil remediation process, which comprises the following steps: adding micro-nano reactors into wet contaminated soil, transferring into a closed container, mixing uniformly, carrying out the soil remediation process, collecting samples at different time periods of the remediation process, separating the micro-nano reactors from the soil by using a flotation method or a screening method, and obtaining the micro-nano reactors with target pollutants or degradation products of the target pollutants on the surfaces of the micro-nano reactors. The surface state of the separated micro-nano reactors and the target pollutants or degradation products are analyzed by using spectroscopy technology, the distribution of the target pollutants, the element valence, the morphology of the nano metal or metal oxide, the crystal form and the change of the valence are judged, the separated micro-nano reactors are washed by using an organic solvent, the target pollutants or degradation products washed out are analyzed, and the types of the target pollutants or degradation products are judged; and the progress of the soil remediation and the interaction mode of the components in the micro-nano reactors and the pollutants in the soil are obtained according to the analysis results.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of environmental remediation, and relates to a method for monitoring the interaction between a micro-nano reactor and soil in a soil remediation process and monitoring the soil remediation process of contaminated soil. BACKGROUND

[0002] With the continuous acceleration of industrialization process of economic development, the problem of soil pollution which is harmful to ecological safety and human health is becoming increasingly serious, and soil pollution has threatened the sustainable use of land resources and the ecological safety of agricultural products. At present, there are many reports about the remediation of contaminated soil by carbon material loaded zero-valent iron, and the composite effect of zero-valent iron and carbon material improves the removal capacity of pollutants in soil. However, during the degradation of pollutants, the morphology, structure, surface properties and distribution changes of zero-valent iron in the carbon carrier are not clear, and there is also a lack of research on how the loaded zero-valent iron contacts with pollutants in soil, the distribution of pollutants in the carbon skeleton and the zero-valent iron-soil micro-interface, and how the degradation products of pollutants are transmitted to the soil.

[0003] The research on the distribution of pollutants on the catalyst / soil micro-interface, the transmission and the distribution of active sites of the catalyst will help us to design more reasonable and efficient catalysts. Therefore, the research on the interaction mode of nanomaterials and pollutants, the reaction process and the exchange of elements with soil is of great significance to improve the utilization rate of remediation agents and reduce the secondary pollution of remediation agents to soil. SUMMARY

[0004] Therefore, the present application provides a method for monitoring the remediation process of contaminated soil, so as to at least partially solve the above technical problems.

[0005] To solve the above technical problems, the present application provides a method for monitoring the remediation process of contaminated soil, comprising:

[0006] The micro-nano reactor is added to the wet contaminated soil, and is transferred to a closed container, and after being mixed uniformly, a first mixture is obtained, wherein the micro-nano reactor comprises a porous carbon carrier and a nano metal or metal oxide loaded on the surface and inside the pores of the porous carbon carrier, and the size and density of the micro-nano reactor are controlled by selecting the porous carbon carrier;

[0007] The first mixture is stirred or left to stand to degrade, mineralize or fix the pollutants in the contaminated soil, and the soil remediation process is carried out;

[0008] Samples are collected at different time periods of the soil remediation process, and the micro-nano reactor is separated from the soil by flotation or screening method according to the size or density of the micro-nano reactor, and the micro-nano reactor with the target pollutants or the degradation products of the target pollutants on the surface is obtained;

[0009] The surface state of the separated micro-nano reactor and the target pollutant or the degradation product of the target pollutant are analyzed by using spectroscopy technology, so as to determine the distribution of the target pollutant, the element valence, the morphology of the nano metal or metal oxide, and the change of the crystal form and valence;

[0010] The separated micro-nano reactor is washed by using an organic solvent, and the target pollutant or the degradation product of the target pollutant washed out is analyzed, so as to determine the concentration of the target pollutant or the type of the degradation product;

[0011] According to the analysis result, the progress of soil remediation and the interaction mode of each component in the micro-nano reactor and the pollutant in the soil are obtained.

[0012] According to the embodiment of the present application, the mass ratio of the micro-nano reactor to the pollutant soil is 1-12.5;

[0013] The water content in the wet pollutant soil is 0.1-2 times the mass of the pollutant soil.

[0014] According to the embodiment of the present application, the stirring or standing time of the first mixture includes 0.5 hours-30 days;

[0015] The different time periods include a time period of 0.5-5 hours.

[0016] According to the embodiment of the present application, the size of the micro-nano reactor and the porous carbon carrier is micron-level to centimeter-level;

[0017] The size of the nano metal or metal oxide is 5-10 nm;

[0018] The density of the micro-nano reactor is less than the density of water.

[0019] According to the embodiment of the present application, the target pollutant includes at least one of monochlorophenol, dichlorophenol, monochloropropanol, monochloromethanol, monochlorobenzyl alcohol, monochlorobenzene ethanol, pentachlorophenol, and trichlorophenol.

[0020] According to the embodiment of the present application, the micro-nano reactor is obtained by the following steps:

[0021] The porous carbon carrier is mixed with an organic metal salt and an organic ligand, or the porous carbon carrier is mixed with a metal-organic framework material, to obtain a mixture;

[0022] The mixture is carbonized under an inert atmosphere to obtain a micro-nano reactor loaded with nano metal or metal oxide.

[0023] According to the embodiment of the present application, the organic ligand includes disodium ethylenediaminetetraacetate;

[0024] The organic metal salt includes at least one of acetate, acetylacetate or oxalate of iron, zinc, copper, palladium or silver.

[0025] According to the embodiment of the present application, the porous carbon carrier includes at least one of biomass charcoal, coke or activated carbon.

[0026] The nano metal includes at least one of nano iron, nano zinc, nano copper, nano palladium, nano silver or nano copper iron.

[0027] The metal oxide includes at least one of iron oxide, copper oxide or manganese oxide.

[0028] According to the embodiment of the present application, the metal-organic framework material includes:

[0029] The amino-modified metal-organic framework material or the imidazole-modified metal-organic framework material, wherein the organic ligand of the amino-modified metal-organic framework material includes 2-amino isophthalic acid, and the organic ligand of the imidazole-modified metal-organic framework material includes at least one of 2-methyl imidazole, 4-methyl imidazole or 5,6-dimethyl benzimidazole.

[0030] The mass ratio of the porous carbon carrier to the metal-organic framework material is 20:1-2:11, and the metal-organic framework material includes iron metal-organic framework material; the mass ratio of the porous carbon carrier to the mixture of the organic metal salt and the organic ligand is 20:1-2:1.

[0031] According to the embodiment of the present application, the carbonization of the mixture in the inert atmosphere includes:

[0032] The carbonization temperature is 700-1000℃.

[0033] The carbonization time is 0.5-5h.

[0034] The inert gas includes nitrogen.

[0035] Based on the technical solution, the method for monitoring the remediation process of contaminated soil provided by the present application at least has the following beneficial effects:

[0036] The application provides a method for monitoring a contaminated soil remediation process, which comprises the following steps: adding a micro-nano reactor into wet soil and mixing uniformly, carrying out a soil remediation process, collecting samples at different reaction time periods, separating the micro-nano reactor from the soil by a flotation method or a screening method, analyzing the surface state of the separated micro-nano reactor and target pollutants or degradation products of the target pollutants by a spectroscopy technology, then washing the separated micro-nano reactor with an organic solvent, and analyzing the target pollutants or the degradation products of the target pollutants washed out. Then, the soil remediation process and the interaction mode of each component in the micro-nano reactor and the pollutants in the soil are obtained according to the analysis results. The micro-nano reactor can be used to comprehensively study the interaction mode of each component in the micro-nano reactor and organic pollutants, the reaction process, the degradation products of the pollutants and the element exchange with the soil, and the element composition, the valence state, the active component crystal form of the micro-nano reactor, the pollutant concentration and the degradation products can be accurately analyzed and detected, so that the interaction mode and the process of the active component in the micro-nano reactor and the pollutants in the soil can be effectively judged, which has important significance for improving the utilization rate of the remediation agent in the soil remediation process, reducing the secondary pollution of the remediation agent to the soil and designing a more reasonable and efficient catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a real object diagram and a scanning electron microscope diagram of an activated carbon / zero-valent iron micro-nano reactor (AC-Fe micro-nano reactor) prepared in Example 1 of the application;

[0038] Figure 2 It is a real object diagram and a scanning electron microscope diagram of an activated carbon / zero-valent iron / copper micro-nano reactor (AC-Fe / Cu micro-nano reactor) prepared in Example 2 of the application;

[0039] Figure 3 It is a scanning electron microscope diagram of a biomass charcoal / zero-valent iron micro-nano reactor (BC-Fe / EDTA) prepared in Example 3 of the application;

[0040] Figure 4 It is an X-ray diffraction (XRD) spectrum diagram of the reactor collected at different time periods in the soil remediation in Application Example 1 of the application;

[0041] Figure 5 It is an Fe 2p, C 1s and O 1s X-ray photoelectron energy (XPS) spectrum diagram of the micro-nano reactor before and after the soil remediation in Application Example 1 of the application;

[0042] Figure 6 It is a Raman spectrum diagram of the micro-nano reactor before and after the soil remediation in Application Example 1 of the application;

[0043] Figure 7X-ray photoelectron spectroscopy (XPS) spectra of Fe 2p, C 1s, O 1s and Cl 2p of the soil for different reaction stages of the present application;

[0044] Figure 8 Scanning electron microscope (SEM) mapping of the soil after reaction of the micro-nano reactor of the present application in application example 1;

[0045] Figure 9 Total ion current chromatogram of the extracted sample for degradation and remediation of the contaminated soil. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to specific embodiments and the accompanying drawings.

[0047] The present application provides a method for monitoring the remediation process of the contaminated soil, comprising:

[0048] The micro-nano reactor is added to the wet contaminated soil, transferred to a closed container, and mixed uniformly to obtain a first mixture, wherein the micro-nano reactor comprises a porous carbon carrier and a nano metal or metal oxide loaded on the surface and inside the pores of the porous carbon carrier, and the size and density of the micro-nano reactor are controlled by selecting the porous carbon carrier;

[0049] The first mixture is stirred or left to stand to degrade, mineralize or fix the pollutants in the contaminated soil, and the soil remediation process is carried out;

[0050] Samples are collected at different time periods of the soil remediation process, and the micro-nano reactor is separated from the soil by flotation or screening method according to the size or density of the micro-nano reactor, to obtain the micro-nano reactor with the target pollutant or the degradation product of the target pollutant on the surface;

[0051] The surface state of the separated micro-nano reactor and the target pollutant or the degradation product of the target pollutant are analyzed by spectroscopy to determine the distribution of the target pollutant, the element valence, the morphology, the crystal form and the valence change of the nano metal or metal oxide;

[0052] The separated micro-nano reactor is washed with an organic solvent, and the target pollutant or the degradation product of the target pollutant washed out is analyzed to determine the concentration of the target pollutant or the types of the degradation product;

[0053] According to the analysis results, the progress of the soil remediation and the interaction mode of each component in the micro-nano reactor and the pollutants in the soil are obtained.

[0054] In the embodiment of the present application, the micro-nano reactors with different sizes or densities are added to the wet contaminated soil, the catalytic ability of the micro-nano reactors can promote the fixation, degradation and mineralization of the contaminants, and the micro-nano reactors after soil remediation can be conveniently collected from the soil by flotation or screening according to their own sizes or densities, the micro-nano reactors with the target contaminants or degradation products of the target contaminants are obtained, and the reaction mode or reaction process of the reactor and the organic contaminants can be further studied by using spectrum technology, such as analyzing the surface state of the micro-nano reactors and the target contaminants or degradation products of the target contaminants, judging the distribution of the target contaminants and the changes of the element valence, the morphology, the crystal form and the valence of the nano metal or metal oxide. Then, the micro-nano reactors are washed by using different polarity organic solvents, and the washing liquid is analyzed by using high-resolution mass spectrometry, so that the degradation degree and degradation products of the organic contaminants can be monitored, and the activity and stability of the micro-nano reactors can be evaluated.

[0055] In addition, the size of the micro-nano reactor can also be adjusted by selecting carbon carriers with different sizes, and according to the size and density, the micro-nano reactors after reaction can be recovered by using the screening method, which does not need to use water or organic solvents, so that the influence of the solvents on the surface properties of the micro-nano reactors and the dissolution of the contained contaminants and degradation products can be avoided, and the element composition, valence, active ingredient crystal form, pollutant concentration and degradation products of the micro-nano reactors can be accurately analyzed and detected, so that the interaction mode and process of the active components of the micro-nano reactors and the contaminants in the soil can be effectively judged.

[0056] According to the embodiment of the present application, the mass ratio of the micro-nano reactor to the contaminated soil is 1-12.5;

[0057] The water content in the wet contaminated soil is 0.1-2 times of the mass of the contaminated soil, and a small amount of water can reduce the influence of water on the activity of the micro-nano reactor.

[0058] According to the embodiment of the present application, the stirring or standing time of the first mixture includes 0.5 hours-30 days;

[0059] The different time periods include a time period of 0.5-5 hours.

[0060] According to the embodiment of the present application, the size of the micro-nano reactor and the porous carbon carrier is micron-level to centimeter-level;

[0061] The size of the nano metal or metal oxide is 5-10 nm;

[0062] The density of the micro-nano reactor is less than the density of water.

[0063] In the embodiment of the present application, the carbon carrier and the micro-nano reactor are controllable in size, the loaded nano metal and metal oxide particles are small and uniformly dispersed, and are not easy to be oxidized, thus having high reaction activity, and can efficiently degrade and remove organic pollutants in soil, and after remediation is completed, the micro-nano reactor can be conveniently separated from the soil according to the size and density of the micro-nano reactor and further studied.

[0064] According to the embodiment of the present application, the target pollutants include at least one of monochlorophenol, dichlorophenol, monochloropropanol, monochloromethanol, monochlorobenzyl alcohol, monochlorobenzene ethanol, pentachlorophenol and trichlorophenol.

[0065] According to the embodiment of the present application, the micro-nano reactor is obtained by the following steps:

[0066] mixing the porous carbon carrier with an organic metal salt and an organic ligand or mixing the porous carbon carrier with a metal-organic framework material to obtain a mixture;

[0067] carbonizing the mixture under an inert atmosphere to obtain the micro-nano reactor loaded with nano metal or metal oxide.

[0068] In the embodiment of the present application, the micro-nano reactor prepared by the method contains nano- to micro-sized metal or metal oxide particles, which have strong reaction activity and are uniformly dispersed in the pores and on the surface of the porous carbon carrier, and can effectively prevent the micro-nano reactor from agglomerating during the reaction with the pollutants in the soil. In addition, the porous carbon carrier has superior adsorption capacity for the pollutants in the soil, which can promote the enrichment of the organic pollutants in the soil on the surface of the reactor, increase the contact of the pollutants with the active sites and active substances on the surface of the nano metal or oxide, and promote the rapid fixation, degradation and removal of the pollutants; the pore structure of the biomass carbon also provides a microenvironment for the nano metal or oxide, and the active substances generated by the reaction of the nano material with dissolved oxygen or water molecules in the soil are gathered in the microenvironment, and the high concentration of active substances can promote the rapid degradation and mineralization of the pollutants adsorbed on the surface of the nano material or biomass carbon.

[0069] According to the embodiment of the present application, the organic ligand includes disodium ethylenediaminetetraacetate.

[0070] The organic metal salt includes at least one of acetate, acetylacetate or oxalate of iron, zinc, copper, palladium or silver.

[0071] According to the embodiment of the present application, the porous carbon carrier includes at least one of biomass carbon, coke and activated carbon.

[0072] The nano metal includes at least one of nano iron, nano zinc, nano copper, nano palladium, nano silver and nano copper-iron.

[0073] The metal oxide includes at least one of iron oxide, copper oxide and manganese oxide.

[0074] In the embodiment of the present application, the nanometal is selected as nanometer zero-valent iron. The nanometer zero-valent iron (nZVI) material has the advantages of rich source, easy production, high activity, low toxicity and non-toxicity, and the nanometer size has high reaction activity to various pollutants, especially heavy metals and organic pollutants. Compared with the microscale counterparts, the nanometer zero-valent iron has relatively high mobility in the soil. However, the nanometer zero-valent iron is easy to be oxidized and agglomerated, which seriously hinders the application of the nanometer zero-valent iron in the degradation of organic pollutants. In order to improve the activity, stability and mobility of the nanometer zero-valent iron, the porous carbon material is used as the carrier of the nanometer zero-valent iron. The nanometer zero-valent iron is loaded on the biochar, which can not only reduce the agglomeration between the nanometer zero-valent iron particles, but also enhance the electron transfer capacity of the nanometer zero-valent iron, inhibit the oxidation of the nanometer zero-valent iron and improve the reaction activity of the nanometer zero-valent iron due to the good electrical conductivity of the biochar. Moreover, the porous carbon carrier has large specific surface area, developed pore structure and a large number of negative charges, and has good adsorption to heavy metals and organic pollutants. In addition, the porous carbon carrier is also a good soil conditioner, which can not only improve the soil quality and soil fertility, but also regulate the abundance of microorganisms.

[0075] In the embodiment of the present application, in addition to the nanometer zero-valent iron, zero-valent copper, iron oxide, manganese oxide and iron-copper composite can also be used for the remediation of pollutants in the soil. These micro-nanometer particles are uniformly loaded in the pore channels and inner and outer surfaces of the porous biochar or activated carbon and the like, which prevents the agglomeration of the nanometer materials during the reaction, so that the obtained micro-nanometer reactor has high reaction activity, and also has the advantages of large specific surface area, high reduction activity, low cost and environmental protection, and plays an increasingly important role in ecological environment protection and pollution control.

[0076] According to the embodiment of the present application, the metal-organic framework material includes:

[0077] The amino-modified metal-organic framework material or the imidazole-modified metal-organic framework material, wherein the organic ligand of the amino-modified metal-organic framework material includes 2-aminoisophthalic acid, and the organic ligand of the imidazole-modified metal-organic framework material includes at least one of 2-methylimidazole, 4-methylimidazole and 5,6-dimethylbenzimidazole.

[0078] According to the embodiment of the present application, the mass ratio of the porous carbon carrier to the metal-organic framework material is 20:1-2:1, and the metal-organic framework material includes iron metal-organic framework material; and the mass ratio of the porous carbon carrier to the mixture of the organic metal salt and the organic ligand is 20:1-2:1.

[0079] According to the embodiment of the present application, the carbonization of the mixture in an inert atmosphere comprises:

[0080] The carbonization temperature is 700-1000℃, the carbonization time is 0.5-5h, and the inert gas comprises nitrogen.

[0081] In the embodiment of the present application, the size, density and morphology of the micro-nano reactor are controllable. According to actual needs, carbon materials such as activated carbon and coke with appropriate size and morphology, or nanoscale-millimeter-scale biomass can be selected as carbon sources. Through the carbonthermal method, the carbon source, organic metal salt and organic ligand or metal-organic framework material are mixed together, and heated in an air-tight manner, which can load nano metal or metal oxide particles on the pores and inner and outer surfaces of carbon materials or biomass carbon with different sizes and morphologies.

[0082] The present application will be described in detail below in conjunction with specific embodiments and drawings, but it should be noted that the embodiments provided by the present application are only for illustration and do not limit the scope of protection of the present application.

[0083] Embodiment 1

[0084] A preparation method of a micro-nano reactor, selecting granular activated carbon as a porous carbon carrier, ferrous acetate (Fe(AC)2) as an organic metal salt, and disodium ethylenediaminetetraacetate (EDTA) as an organic ligand, wherein the mass of the activated carbon carrier is 20g, the mass ratio of Fe(AC)2 and EDTA is 3:1, and the mass ratio of the sum of Fe(AC)2 and EDTA to the mass of the activated carbon carrier is 1:20-1:2. After mixing, carbonization is carried out in a nitrogen atmosphere to obtain an activated carbon / zero-valent iron micro-nano reactor (AC-Fe micro-nano reactor), wherein the carbonization temperature is 700-1100℃, and the carbonization time is 1-5h.

[0085] The particle size and morphology structure of the activated carbon / zero-valent iron micro-nano reactor are analyzed by using a Japanese Hitachi S-8020 field emission scanning electron microscope.

[0086] Figure 1 The present application uses the real object diagram and scanning electron microscope diagram of the activated carbon / zero-valent iron micro-nano reactor (AC-Fe micro-nano reactor) prepared in Embodiment 1.

[0087] Embodiment 2

[0088] A preparation method of a micro-nano reactor, selecting granular activated carbon as a porous carbon carrier, ferrous acetate and copper acetate (Cu(AC)2) as organic metal salts, and disodium ethylenediaminetetraacetate as an organic ligand, the mass of the activated carbon carrier being 20 g, the mass ratio of Fe(AC)2 and Cu(AC)2 being 4:1-1:2, the mass ratio of the sum of Fe(AC)2 and Cu(AC)2 to EDTA being 3:1, and the mass ratio of the sum of Fe(AC)2+Cu(AC)2+EDTA to the activated carbon carrier being 1:20-1:2, mixing them and then performing carbonization under a nitrogen atmosphere to obtain an activated carbon / zero-valent iron / copper micro-nano reactor (AC-Fe / Cu micro-nano reactor), wherein the carbonization temperature is 700-1100 DEG C, and the carbonization time is 1-5 h.

[0089] The particle size and morphological structure of the activated carbon / zero-valent iron / copper micro-nano reactor are analyzed by using a Japanese Hitachi S-8020 field emission scanning electron microscope.

[0090] Figure 2 The actual picture and scanning electron microscope picture of the activated carbon / zero-valent iron / copper micro-nano reactor (AC-Fe / Cu micro-nano reactor) prepared in Example 2 are shown.

[0091] Example 3

[0092] A preparation method of a micro-nano reactor, selecting coffee grounds as a porous carbon carrier, ferrous acetate as an organic metal salt, and disodium ethylenediaminetetraacetate as an organic ligand, the mass ratio of Fe(AC)2 to EDTA being 3:1, and the mass ratio of the sum of Fe(AC)2 and EDTA to coffee grounds being 1:10-1:2, mixing them and then performing high-temperature carbonization under a nitrogen atmosphere to obtain a biomass carbon / zero-valent iron micro-nano reactor (BC-Fe / EDTA), wherein the carbonization temperature is 700-1100 DEG C, and the carbonization time is 1-5 h.

[0093] The particle size and morphological structure of the biomass carbon / zero-valent iron micro-nano reactor are analyzed by using a Japanese Hitachi S-8020 field emission scanning electron microscope.

[0094] Figure 3 The scanning electron microscope picture of the biomass carbon / zero-valent iron micro-nano reactor (BC-Fe / EDTA) prepared in Example 3 is shown.

[0095] As can be seen from the scanning electron microscope pictures of the micro-nano reactors prepared in the above Examples 1, 2 and 3, the activated carbon and the biomass carbon have a porous structure, and the zero-valent iron or the zero-valent iron / copper is mainly distributed on the inner surface and the pores of the biomass carbon.

[0096] Application Example 1

[0097] Using the biochar / zero-valent iron micro / nano reactor (BC-Fe / EDTA) prepared in Example 3 as the remediation material, pentachlorophenol (PCP), an organochlorine pesticide, was removed from the soil. The performance of the biochar / zero-valent iron micro / nano reactor and the reaction process of pentachlorophenol with the reactor were studied. The specific contents are as follows:

[0098] In this application example 1, pentachlorophenol, an organochlorine pesticide, was selected as the representative pollutant. The concentration of this pesticide in the soil was 200 mg / kg. A biochar / zero-valent iron micro-nano reactor was used to remove pentachlorophenol from the soil. The amount of biochar / zero-valent iron micro-nano reactor added was 10% of the soil mass.

[0099] The steps are as follows: A 15mL PE centrifuge tube was used as the reaction vessel. The soil mass was 2g, the water addition was 0.2-2mL, and the micro / nano reactor addition was 0.2g. After mixing, the mixture was placed in a shaker and slowly shaken at room temperature. Soil samples were collected after 2h, 6h, 12h, and 24h of reaction. A combination of water flotation and magnetic separation was used to collect the biochar / zero-valent iron micro / nano reactor in the soil. XRD, XPS, and Raman spectroscopy were used for analysis. To analyze the PCP removal efficiency and degradation products, methanol was used to extract the soil and micro / nano reactor. After concentration, the extract was analyzed by HPLC-MS.

[0100] The following provides a detailed explanation of various spectroscopic analyses of micro / nano reactors.

[0101] Figure 4 The images show X-ray diffraction (XRD) spectra of the reactor collected at different time periods during soil remediation in Application Example 1 of this invention.

[0102] Depend on Figure 4 It can be seen that during the remediation process, the diffraction peak of iron carbide (Fe5C2) disappeared. No diffraction peak of Fe5C2 was observed in the XRD spectra of the recovered materials at different reaction times. The diffraction peak of zero-valent iron (α-Fe) decreased with the extension of reaction time, but the diffraction peak of α-Fe could still be observed. The peak intensity was significantly reduced, indicating that both Fe5C2 and α-Fe components played a role in the degradation of pentachlorophenol. In addition, the diffraction peak of Fe3O4 was also observed in the spectrum of the recovered biochar / zero-valent iron micro / nano reactor, which mainly came from the oxidation of zero-valent iron.

[0103] Figure 5 The images show the Fe 2p, C 1s, and O 1s X-ray photoelectron spectroscopy (XPS) spectra of the micro / nano reactor before and after soil remediation in Application Example 1 of this invention.

[0104] Depend on Figure 5The XPS spectrum of Fe 2p shows that the valence state of iron element on the surface of the micro-nano reactor before and after the reaction does not change, and still mainly exists in the form of Fe 2+ and Fe 3+ mixed state; from Figure 5 The C 1s spectrum shows that the micro-nano reactor after repairing the soil does not change significantly compared with before repairing; from Figure 5 The O 1s spectrum shows that the O 1s spectrum peak shape of the micro-nano reactor after the reaction is widened, which is mainly due to the oxidation of zero-valent iron and the attachment of SiO2 particles in the soil. These results show that the zero-valent iron and biomass charcoal in the micro-nano reactor recovered by flotation + magnetic separation are not oxidized.

[0105] The Raman spectrum of the micro-nano reactor before and after repairing in the application example 1 of the application is characterized by LabRAM HR Evolution Raman spectrum, so as to study the change of the biomass charcoal on the surface and the possible iron oxide, and the laser light source λ = 532 nm.

[0106] Figure 6 It is the Raman spectrum of the micro-nano reactor before and after repairing the soil in the application example 1 of the application.

[0107] From Figure 6 It can be seen that before and after the reaction, the intensity of the D band (defect carbon) at 1350 cm -1 and the G band at 1580 cm -1 of the Raman spectrum does not change, indicating that the biomass charcoal in the recovered reactor does not change significantly; in the range of 100-1300 cm -1 , no Raman absorption peak of iron oxide and iron hydroxide is observed, which proves that only a small amount of zero-valent iron on the surface of the reactor is oxidized.

[0108] Further, the biomass charcoal / zero-valent iron micro-nano reactor in the soil after 2h, 6h and 12h of reaction is collected by screening method. XPS is used to analyze the element composition and valence state on the surface of the soil after repairing, and SEM, SEM-EDX are used to observe the morphology and element composition and distribution of the soil and the reactor at different repair stages.

[0109] Figure 7 It is the XPS spectrum of Fe 2p, C 1s, O 1s and Cl 2p of the soil repaired at different reaction stages.

[0110] As Figure 7 shown in Fe 2p, the iron element Fe 3+The increase of the content is mainly from the oxidation of the zero-valent iron released from the reactor. The rapid oxidation of the zero-valent iron in the soil further illustrates that the biomass charcoal can effectively protect the zero-valent iron. Figure 7 The increase of the content is mainly from the oxidation of the zero-valent iron released from the reactor. The rapid oxidation of the zero-valent iron in the soil further illustrates that the biomass charcoal can effectively protect the zero-valent iron. Figure 7 The signal intensity of the Cl 2p XPS spectrum of the soil after the repair increases, and mainly exists in the form of inorganic Cl ions, which is mainly from the degradation of pentachlorophenol, indicating that most of the pentachlorophenol is mineralized and dechlorinated.

[0111] Further, the change of the zero-valent iron in the micro-nano reactor and the distribution of the target pollutants are studied.

[0112] Figure 8 The scanning electron microscope scanning phase (SEM-mapping) diagram of the soil after the repair of the biomass charcoal loaded zero-valent iron micro-nano reactor in the application example 1 is shown.

[0113] As shown in Figure 8 In the repair reaction process, the nano zero-valent iron in the micro-nano reactor migrates from the inner pore channel of the biomass charcoal to the outer surface, which is mainly caused by the damage of the biomass charcoal and the release to the soil. Figure 8 In the repair reaction process, the nano zero-valent iron in the micro-nano reactor migrates from the inner pore channel of the biomass charcoal to the outer surface, which is mainly caused by the damage of the biomass charcoal and the release to the soil. Figure 8 It can also be observed that the pentachlorophenol pollutants are mainly enriched on the surface of the zero-valent iron and are degraded by the zero-valent iron.

[0114] In addition, the element composition in the soil before and after the repair is analyzed, and the specific content is shown in Table 1. The contents of C, Na, K, Mg, Ca, Cl and Fe and other elements in the soil after the repair increase significantly, indicating that the damaged biomass charcoal, soluble elements, active components, pollutant mineralization products and zero-valent iron in the reactor migrate to the soil. These components increase the nutrients in the soil, thereby facilitating the growth of microorganisms.

[0115] Table 1 Element composition of the soil before and after the repair (mass percentage %)

[0116] Element Original soil Soil after 12h remediation Soil after 24h remediation O 51.9 56.26 57.02 Si 32.67 16.38 15.1 Al 3.18 3.61 3.55 C 6.32 7.43 8.01 Ca 2.01 3.71 3.64 Fe 1.89 5.41 5.66 Mg 0.97 2.24 2.5 K 0.76 1.82 2.2 Na 0.26 2.9 2.05 Cl 0.03 0.24 0.27

[0117] Further, methanol was used to extract the organic pollutants and their degradation products in the soil containing the reactor at different reaction stages, and Agilent 6540 high-pressure liquid chromatography-quadrupole time-of-flight mass spectrometry was used for detection.

[0118] Figure 9 Total ion chromatogram of the extracted sample of the contaminated soil degradation and remediation of the application.

[0119] As shown in Figure 9 , after 24h of degradation of the contaminated soil, solvent peaks can be detected, and almost no chlorinated intermediate degradation products can be detected, further confirming that the micro-nano reactor has high mineralization capacity for pentachlorophenol.

[0120] Based on the above analysis, the micro-nano reactor and the method for monitoring the remediation process of contaminated soil provided by the application has the following advantages:

[0121] (1) The raw materials are easy to obtain and the cost is low. In the application, the carbon material is selected from activated carbon, coke and the like, and the biomass charcoal is selected from kitchen waste or agricultural and forestry waste and the like.

[0122] (2) The size, density and morphology of the micro-nano reactor are controllable. According to actual needs, suitable size and morphology of activated carbon, coke and other carbon materials or nanoscale to millimeter scale biomass can be selected as carbon source. By carbon thermal method, nano metal or metal oxide particles are loaded on the pore channels and inner and outer surfaces of carbon materials or biomass charcoal together with metal source and organic ligand in an air-tight heating process.

[0123] (3) The micro-nano reactor has high activity. Since the metal or metal oxide particles in the micro-nano reactor are small in size, uniformly dispersed and not easy to oxidize, it has high reaction activity and can efficiently degrade organic pollutants; in addition, the porous biomass charcoal or carbon material has high specific surface area and adsorption sites, which can promote the adsorption and removal of pollutants.

[0124] (4) Easy to recycle, convenient for subsequent analysis of surface properties of active components of the reactor and extraction of pollutants. Due to the large size of the reactor, it can be quickly separated from the soil by screening method. Since the separation process basically does not use solvents and the like, the surface properties of the micro-nano reactor and the concentration of pollutants and degradation products do not change, so the element composition, valence state, active component crystal form of the micro-nano reactor and the concentration of pollutants and degradation products can be accurately analyzed and detected, so as to effectively judge the interaction mode and process of the active components of the micro-nano reactor and the pollutants in the soil.

[0125] The above specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the present application, and it should be understood that the above are only specific embodiments of the present application and are not intended to limit the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for monitoring a remediation process of contaminated soil, comprising: adding micro-nano reactors into a wet contaminated soil, transferring into a closed container, mixing uniformly to obtain a first mixture, wherein the micro-nano reactors comprise a porous carbon carrier and nano metals or metal oxides loaded on the surface and inside of the porous carbon carrier, and the size and density of the micro-nano reactors are controlled by selecting the porous carbon carrier; stirring or standing the first mixture to degrade, mineralize or immobilize the contaminants in the contaminated soil, and performing a soil remediation process; collecting samples at different time periods of the soil remediation process, and separating the micro-nano reactors from the soil by flotation or screening according to the size or density of the micro-nano reactors to obtain micro-nano reactors with target contaminants or degradation products of the target contaminants on the surface; analyzing the surface state of the separated micro-nano reactors and the target contaminants or degradation products of the target contaminants by spectroscopy to determine the distribution of the target contaminants, the morphology, crystal form and valence state of the nano metals or metal oxides, and the changes of the valence state; washing the separated micro-nano reactors with an organic solvent and analyzing the target contaminants or degradation products of the target contaminants washed out to determine the concentration of the target contaminants or the types of the degradation products; and obtaining the progress of the soil remediation and the interaction mode of each component in the micro-nano reactors and the contaminants in the soil according to the analysis results. 2.The method for monitoring a remediation process of contaminated soil according to claim 1, wherein: the mass ratio of the micro-nano reactors to the contaminated soil is 1-12.5; and the water content in the wet contaminated soil is 0.1-2 times the mass of the contaminated soil. 3.The method for monitoring a remediation process of contaminated soil according to claim 1, wherein: the stirring or standing time of the first mixture comprises 0.5 hours-30 days; and the different time periods comprise 0.5-5 hours. 4.The method for monitoring a remediation process of contaminated soil according to claim 2, wherein: the size of the micro-nano reactors and the porous carbon carrier is micron-level to centimeter-level; the size of the nano metals or metal oxides is 5-10 nm; and the density of the micro-nano reactors is less than the density of water; the target contaminants comprise at least one of monochlorophenol, dichlorophenol, monochloropropanol, monochloromethanol, monochlorobenzyl alcohol, monochlorobenzene ethanol, pentachlorophenol and trichlorophenol; the micro-nano reactors are obtained by: mixing the porous carbon carrier with an organic metal salt and an organic ligand or mixing the porous carbon carrier with a metal-organic framework material to obtain a mixture; and carbonizing the mixture under an inert atmosphere to obtain the micro-nano reactors loaded with nano metals or metal oxides. 7.The method for monitoring a remediation process of contaminated soil according to claim 6, wherein: the organic ligand comprises disodium ethylenediaminetetraacetate; and the organic metal salt comprises at least one of acetate, acetylacetate or oxalate of iron, zinc, copper, palladium or silver. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 5. The method of monitoring a remediation process of a contaminated soil according to claim 1, wherein, ​ 6. The method of monitoring a remediation process of a contaminated soil according to claim 1, wherein, ​ ​ ​ ​ ​ ​ 8. The method of claim 6, wherein: the porous carbonaceous support comprises at least one of biomass char, coke, and activated carbon; the nano-metal comprises at least one of nano-iron, nano-zinc, nano-copper, nano-palladium, nano-silver, and nano-copper-iron; the metal oxide comprises at least one of iron oxide, copper oxide, and manganese oxide.

9. The method of monitoring a remediation process of a contaminated soil according to claim 6, wherein, the metal-organic framework material comprises: an amino-modified metal-organic framework material or an imidazolyl-modified metal-organic framework material, wherein the organic ligand of the amino-modified metal-organic framework material comprises 2-amino isophthalic acid, and the organic ligand of the imidazolyl-modified metal-organic framework material comprises at least one of 2-methyl imidazole, 4-methyl imidazole, and 5,6-dimethyl benzimidazole; a mass ratio of the porous carbonaceous support to the metal-organic framework material is 20:1 to 2:1, and the metal-organic framework material comprises an iron metal-organic framework material; a mass ratio of the porous carbonaceous support to the mixture of the organic metal salt and the organic ligand is 20:1 to 2:

1.

10. The method of monitoring a remediation process of a contaminated soil according to claim 6, wherein, the carbonization of the mixture under an inert atmosphere comprises: a temperature of the carbonization is 700-1000°C; a time of the carbonization is 0.5-5h; the inert gas comprises nitrogen.

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