In-situ seepage distribution flow-type composite wave absorbing material and preparation method and application thereof

Abstract

The present invention relates to the technical field of absorbing materials, and discloses a flowable composite absorbing material with in-situ seepage distribution, a preparation method and application thereof. The flowable composite absorbing material prepared by the present invention using agricultural and forestry waste as raw materials is not only low in preparation cost and environmentally friendly, but also can effectively improve the penetration ability, interception distribution ability and penetration speed of the flowable composite absorbing material in the soil by adding thickener and glycerol, so that the flowable composite absorbing material has good in-situ penetration distribution characteristics, and helps to improve the absorbing performance of the flowable composite absorbing material. When it is applied to soil repair, the flowable composite absorbing material can be autonomously dispersed in the soil and distributed in the soil as evenly as possible, thereby effectively simplifying the soil repair process, reducing the energy consumption and cost of soil repair, and improving the soil repair effect.

Description

Technical Field

[0001] The present invention relates to the technical field of absorbing materials, and in particular to a flow-type composite absorbing material with in-situ seepage distribution, a preparation method and application thereof. Background Art

[0002] The contents in this section merely provide background information related to the present invention and may not constitute prior art.

[0003] Polycyclic aromatic hydrocarbons (PAHs) are common and difficult-to-degrade organic pollutants. Due to their high hydrophobicity, low vapor pressure and water solubility, they are more likely to accumulate in the soil. Since soil containing PAHs has serious hazards to the environment and human health, it is usually necessary to repair the soil containing PAHs to remove PAHs in the soil as much as possible.

[0004] Traditional methods of repairing soil containing PAHs, such as chemical, biological and physical methods, usually have problems such as low efficiency, long time consumption, high cost, and easy to cause secondary pollution to the environment or damage the soil structure. For this reason, microwave heating remediation technology that uses microwave heating to repair soil has also emerged at this stage. Compared with the thermal desorption technology in physical methods, microwave heating remediation technology is an inside-out heating technology that can selectively heat at the molecular level and cause little damage to the soil. At the same time, microwave heating remediation technology can overcome heat and mass transfer limitations through direct interaction between electromagnetic waves and soil, thereby significantly reducing the time required for soil repair, improving repair efficiency, and reducing repair costs and the risk of further soil contamination.

[0005] When the organic pollutants in the soil have low polarity or no polarity, the ability of the organic pollutants and even the soil to absorb microwaves is weak. Relying on microwaves to directly heat the organic pollutants in the soil is less effective in removing the organic pollutants. Therefore, in the current microwave heating remediation technology, absorbing materials (that is, microwave absorbing materials) are usually added to the soil to enhance the soil's ability to absorb microwaves, thereby improving the removal rate of organic pollutants.

[0006] However, the known absorbing materials that can be used in microwave heating repair technology generally cannot achieve in-situ seepage distribution. Specifically, most of the known absorbing materials that can be used in microwave heating repair technology are in the form of solid particles, which do not have the ability to flow independently and cannot be dispersed in the soil as evenly as possible. Instead, they need to rely on mechanical stirring to better add such absorbing materials to the soil, which increases the process and cost required for soil repair. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a flow-type composite absorbing material with in-situ seepage distribution and a preparation method and application thereof, so as to at least overcome the technical problem that the known absorbing materials applicable to microwave heating repair technology cannot disperse autonomously in the soil and be distributed in the soil as evenly as possible.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] In a first aspect, the present invention discloses a method for preparing a flow-type composite absorbing material with in-situ seepage distribution, comprising the following steps:

[0010] Step S1. Using agricultural and forestry waste as raw materials, preparing colloidal absorbing particles;

[0011] Step S2. Dispersing the colloidal absorbing particles obtained in step S1 into a viscous aqueous solution containing a thickener, and adding glycerin to obtain a flowable composite absorbing material.

[0012] Furthermore, the step S1 specifically includes:

[0013] Step S11. Pre-treating the agricultural and forestry waste to obtain agricultural and forestry waste particles of a predetermined mesh size;

[0014] Step S12. Soaking the agricultural and forestry waste particles obtained in step S11 in a FeSO4 solution, filtering after soaking, drying the filtrate after filtering, and calcining the filtrate after drying to obtain a powdered absorbing material;

[0015] Step S13. Grinding the powdered absorbing material obtained in step S12, and separating the powdered absorbing material of a predetermined particle size by ultrasonic static method after grinding;

[0016] Step S14. The powdered absorbing material of the predetermined particle size separated in step S13 is mixed with ultrapure water, and then subjected to water bath ultrasound to obtain a suspension; the suspension is then allowed to stand, and then the suspension after standing is filtered through a filter membrane, and the filter membrane is dried after filtration, and finally the powder on the dried filter membrane is obtained as colloidal absorbing particles.

[0017] Furthermore, in step S12, the concentration of the FeSO4 solution is 0.3-0.5 mol / L, and the agricultural and forestry waste particles are immersed in the FeSO4 solution for 1 hour.

[0018] Furthermore, in the step S12, the specific process of calcining the dried filtrate is as follows: compacting the dried filtrate and placing it in a ceramic crucible, sealing the ceramic crucible and placing it in a muffle furnace for calcination;

[0019] The calcination temperature in the muffle furnace is 550-650°C, the calcination time is 2.5-3.5h, and the heating rate is 5-10°C / min.

[0020] Furthermore, in the step S11, the process of pre-treating the agricultural and forestry waste to obtain agricultural and forestry waste particles of a predetermined mesh size is: washing, drying, crushing and screening the agricultural and forestry waste in sequence to obtain agricultural and forestry waste particles of a predetermined mesh size;

[0021] Among them, the predetermined mesh size of agricultural and forestry waste particles is 20 meshes.

[0022] Furthermore, in the step S13, the particle size of the powdered absorbing material separated by the ultrasonic static method is less than 10 μm;

[0023] In step S14, the ratio of the powdered absorbing material with a predetermined particle size to ultrapure water is 1:100; the water bath ultrasound is performed for 30 minutes; the suspension is allowed to stand for 1 hour; and the filter membrane used for filtration is a 0.45 μm mixed fiber resin filter membrane.

[0024] Furthermore, in the step S2, the viscous aqueous solution containing the thickener is obtained by dissolving the thickener in ultrapure water;

[0025] Wherein, the mass ratio of thickener to ultrapure water is: (2g-3g): (100ml-200ml);

[0026] Wherein, the thickener is carboxymethyl cellulose, xanthan gum or guar gum.

[0027] Furthermore, in step S2, the volume ratio of the mass of the colloidal absorbing particles, the mass of glycerol and the viscous aqueous solution is: (1g-3g): (1g-3g): (100ml-200ml).

[0028] In a second aspect, the present invention discloses a flow-type composite absorbing material with in-situ seepage distribution, which is prepared by the method for preparing the flow-type composite absorbing material with in-situ seepage distribution described above.

[0029] In a third aspect, the present invention discloses an application of the above-mentioned flow-type composite absorbing material with in-situ seepage distribution in the field of microwave absorption, especially in the field of soil remediation based on microwave heating remediation technology.

[0030] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0031] The flowable composite absorbing material prepared by the present invention using agricultural and forestry waste as raw materials is not only low in preparation cost and environmentally friendly, but also can effectively improve the penetration ability, interception distribution ability and penetration speed of the flowable composite absorbing material in the soil by adding a thickener and glycerol, so that the flowable composite absorbing material has good in-situ penetration distribution characteristics, and is helpful to improve the absorbing performance of the flowable composite absorbing material. When the flowable composite absorbing material is used to repair soil, the flowable composite absorbing material can be autonomously dispersed in the soil and distributed in the soil as evenly as possible, thereby effectively simplifying the soil repair process, reducing the energy consumption and cost of soil repair, and improving the soil repair effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A reflection loss diagram of a powdered absorbing material disclosed in an embodiment of the present invention;

[0033] Figure 2 The SEM scanning spectrum image and EDS element spectrum image of the powdered absorbing material disclosed in the embodiment of the present invention; wherein, Figure 2 (a) is the SEM scanning spectrum of the powdered absorbing material; Figure 2 (b) is the EDS element spectrum of C element in powdered absorbing material; Figure 2 (c) is the EDS element spectrum of O element in powdered absorbing material; Figure 2 (d) is the EDS element spectrum of Fe element in the powdered absorbing material;

[0034] Figure 3 The permeation curve diagram of the flowable composite absorbing material disclosed in the embodiment of the present invention and the absorbing material without adding thickener after the column migration test;

[0035] Figure 4 The mass distribution diagram of retained particles after column migration test of the flowable composite absorbing material disclosed in the embodiment of the present invention and the absorbing material without adding thickener;

[0036] Figure 5 The permeation curves of the flowable composite absorbing materials with different CMC concentrations added after the column migration test disclosed in the embodiments of the present invention are shown;

[0037] Figure 6 This is a distribution diagram of retained particle mass after a column migration test of a flowable composite absorbing material with different CMC concentrations added according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with specific implementation methods. It should be noted that the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The embodiment of the present invention discloses a method for preparing a flow-type composite absorbing material with in-situ seepage distribution. The flow-type composite absorbing material prepared based on the preparation method has the advantages of good in-situ seepage distribution characteristics, low preparation cost, environmental friendliness, ability to simplify the soil remediation process, and ability to reduce energy consumption and cost when remediating soil when applied to the field of soil remediation, especially when applied to the remediation of soil containing PAHs.

[0040] The term "in-situ seepage distribution" described in the present invention refers to the penetration and interception distribution of the absorbing material in the soil.

[0041] The method for preparing the flow-type composite absorbing material with in-situ seepage distribution disclosed in the embodiment of the present invention may include the following steps:

[0042] Step S1. Using agricultural and forestry waste as raw materials, colloidal microwave-absorbing particles are prepared.

[0043] It is worth noting that the agricultural and forestry wastes described in the present invention may be agricultural wastes or forestry wastes. For example, the agricultural and forestry wastes may be, but are not limited to, walnut shells, coconut shells, almond shells, peach pits, and the like.

[0044] Moreover, the present invention uses agricultural and forestry waste as raw materials for preparing the flowable composite absorbing material, thereby greatly reducing the preparation cost of the flowable composite absorbing material, while achieving the rational reuse of waste resources, meeting the requirements of sustainable development, and the prepared flowable composite absorbing material is environmentally friendly when repairing soil and will not cause secondary pollution to the environment.

[0045] Wherein, step S1 may specifically include:

[0046] Step S11: pre-treating the agricultural and forestry waste to obtain agricultural and forestry waste particles of a predetermined mesh size.

[0047] Specifically, in step S11, the process of pre-treating the agricultural and forestry waste to obtain agricultural and forestry waste particles of a predetermined mesh size is: washing, drying, crushing and screening the agricultural and forestry waste in sequence to obtain agricultural and forestry waste particles of a predetermined mesh size.

[0048] Among them, in the above process, the washing medium used for washing can be deionized water, the crushing adopts a crusher, and the screen used for screening can be a 20-mesh screen, that is, the predetermined mesh number of the above-mentioned agricultural and forestry waste particles can be 20 meshes.

[0049] Step S12: Soak the agricultural and forestry waste particles obtained in step S11 in a FeSO4 solution, filter the solution after soaking, dry the filtered material after filtering, and calcine the filtered material after drying to obtain a powdered absorbing material.

[0050] Specifically, in step S12, the concentration of the FeSO4 solution is 0.3-0.5 mol / L, and the agricultural and forestry waste particles can be immersed in the FeSO4 solution for 1 hour; the filtrate can be dried in an oven, and the temperature during drying in the oven can be 60-100°C, for example 60°C, and the drying time can be 8 hours.

[0051] Specifically, in step S12, the specific process of calcining the dried filtrate is as follows: compacting the dried filtrate and placing it in a ceramic crucible, sealing the ceramic crucible with aluminum foil, and placing it in a muffle furnace for calcination. The calcination temperature during calcination in the muffle furnace may be 550-650° C., for example, 600° C., the calcination time may be 2.5-3.5 h, for example, 3 h, and the heating rate may be 5-10° C. / min, for example, 5° C. / min.

[0052] It is worth noting that the present invention can better introduce magnetic phases (such as Fe3O4) by soaking agricultural and forestry waste particles in FeSO4 solution and then calcining them, which is beneficial to enhance the magnetic loss capacity of the colloidal absorbing particles prepared subsequently.

[0053] Specifically, by testing and calculating the powdered absorbing materials with 10 different thicknesses disclosed in the embodiments of the present invention, the following results are obtained: Figure 1 The reflection loss diagram of the powdered absorbing material is shown in FIG. The thicknesses of the 10 powdered absorbing materials with different thicknesses are: Figure 1 It should be noted that the thickness of the powdered absorbing material described here can be regarded as the thickness of a certain number of powdered absorbing materials piled up, not the thickness of a single powdered absorbing material.

[0054] like Figure 1As shown in the figure, when the frequency is 6.95GHz and the thickness is 5mm, the reflection loss of the powdered absorbing material reaches the maximum, which is about -17.6dB. As the thickness decreases, the maximum reflection loss gradually decreases, and the position of the maximum reflection loss gradually moves to high frequencies. The powdered absorbing material shows good magnetic loss capability in the 1-18GHz frequency band.

[0055] Figure 2 The SEM scanning spectrum image and EDS element spectrum image of the powdered absorbing material disclosed in the embodiment of the present invention are shown. Figure 2 (a) is the SEM scanning spectrum of the powdered absorbing material; Figure 2 (b) is the EDS element spectrum of C element in powdered absorbing material; Figure 2 (c) is the EDS element spectrum of O element in powdered absorbing material; Figure 2 (d) is the EDS elemental spectrum of Fe element in powdered absorbing material.

[0056] Depend on Figure 2 (a) It can be seen that the powdered absorbing material prepared by soaking in FeSO4 solution and calcining not only inherits the two types of pores in the raw material itself, but also forms a third type of pores. Among them, the first type of pores in the raw material itself are larger pores with a pore size distribution between 12.5-36.4μm, and the second type of pores are smaller pores with a pore size distribution between 0.7-2.2μm.

[0057] Among them, the third type of holes formed on the powdered absorbing material obtained after soaking and calcining are holes with a pore size distribution between 23-200nm. The pore size of this type of hole is much smaller than the pore size of the two pores in the raw material itself. The complex and diverse porous structure on the powdered absorbing material provides a large number of transmission channels for the incident electromagnetic waves, thereby helping to improve the absorbing performance of the finally prepared flowable composite absorbing material. Figure 2 As can be seen from the local enlarged image in (a), Fe304 nanoparticles with a diameter of about 150 nm are evenly attached to the surface of the powdered absorbing material. These nanoparticles are decorated on the surface of the powdered absorbing material or filled inside the powdered absorbing material.

[0058] And, if Figure 2 (b) Figure 2 (c) and Figure 2 As shown in (d), from the distribution area of ​​C element, O element and Fe element, a layer of Fe304 is evenly distributed on the surface of the powdered absorbing material, which means that ferrite has been successfully loaded on the powdered absorbing material, and the content of Fe element on the scanning surface can reach 21.03%.

[0059] Step S13: Grinding the powdered absorbing material obtained in step S12, and separating the powdered absorbing material with a predetermined particle size by using an ultrasonic static method after grinding.

[0060] In step S13, the particle size of the powdered absorbing material separated by the ultrasonic static method is less than 10 μm. The present invention separates the required powdered absorbing material by the ultrasonic static method, which is conducive to more accurate control of the particle size of the separated powdered absorbing material.

[0061] Step S14. The powdered absorbing material of predetermined particle size separated in step S13 is mixed with ultrapure water, and then subjected to water bath ultrasound to obtain a suspension; the suspension is then allowed to stand, and then the suspension after standing is filtered through a filter membrane, and the filter membrane is dried after filtration, and finally the powder on the dried filter membrane is obtained as colloidal absorbing particles.

[0062] Specifically, in step S14, the ratio of powdered absorbing material of predetermined particle size to ultrapure water can be 1:100; the time for water bath ultrasound can be 30 minutes; the time for the suspension to stand can be 1 hour; the filter membrane used for filtration can be a 0.45 μm mixed fiber resin filter membrane; the filter membrane can be dried in an oven, and the drying temperature in the oven can be 60-100°C, for example 65°C, and the drying time can be 24 hours.

[0063] Step S2. Based on the colloidal absorbing particles prepared in step S1, the colloidal absorbing particles obtained in step S1 are dispersed in a viscous aqueous solution containing a thickener, and glycerol (GLY) is added to obtain the flowable composite absorbing material disclosed in the embodiment of the present invention. The flowable composite absorbing material can also be regarded as colloidal biochar.

[0064] Specifically, in step S2, a viscous aqueous solution containing a thickener is obtained by dissolving the thickener in ultrapure water, wherein the mass ratio of the thickener to the ultrapure water may be: (2g-3g): (100ml-200ml). The thickener may be carboxymethyl cellulose (CMC), xanthan gum or guar gum, etc.

[0065] In step S2, the volume ratio of the mass of the colloidal absorbing particles, the mass of glycerol and the viscous aqueous solution can be: (1g-3g): (1g-3g): (100ml-200ml).

[0066] In order to further verify that the flowable composite absorbing material prepared by the preparation method disclosed in the present invention has good in-situ seepage distribution characteristics, especially the fluidity of the colloidal absorbing particles in the flowable composite absorbing material in the unsaturated porous medium, the inventors of the present invention also took the flowable composite absorbing material prepared by the present invention and the absorbing material without adding a thickener as test objects, and carried out column migration tests respectively.

[0067] The above-mentioned absorbing material without thickener can be understood as the absorbing material prepared by replacing the viscous aqueous solution containing thickener in the above-mentioned step S2 with an aqueous solution without thickener (such as ultrapure water).

[0068] In order to simplify the description, the flowable composite absorbing material prepared by the present invention is taken as an example to explain the specific process of the column migration test.

[0069] Specifically, the process of conducting a column migration test on the flow-type composite absorbing material prepared by the present invention is as follows:

[0070] a. 60 g of unsaturated porous medium is wet loaded in a vertical plexiglass column; wherein the length of the plexiglass column may be 20 cm, the inner diameter of the plexiglass column may be 1.6 cm, and the unsaturated porous medium may be quartz sand or sand.

[0071] b. Wrap the bottom of the organic glass column with a 120-mesh nylon mesh to prevent the unsaturated porous medium in the organic glass column from leaking out while not hindering the flow-type composite absorbing material prepared by the present invention from passing through.

[0072] c. The flowable composite absorbing material prepared by the present invention is passed from the top of the organic glass column into the organic glass column at an appropriate flow rate, and the flowable composite absorbing material is maintained on the surface of the unsaturated porous medium in the organic glass column to ensure that the water head remains unchanged.

[0073] d. Allow the flowing composite absorbing material to naturally penetrate the unsaturated porous medium in the organic glass column under the action of gravity, and collect the leaching solution from the bottom of the organic glass column. Then, use ultraviolet spectrophotometry to measure the concentration of the colloidal absorbing particles in the leaching solution to obtain the flow of the colloidal absorbing particles in the flowing composite absorbing material in the unsaturated porous medium.

[0074] e. Push out the unsaturated porous medium in the organic glass column as a whole, divide the pushed out unsaturated porous medium into 10 parts, and put the 10 parts of unsaturated porous medium into different centrifuge tubes. Then, add 10 ml of ultrapure water into each centrifuge tube, and use ultrasound to separate the colloidal absorbing particles in each centrifuge tube into the ultrapure water. Finally, measure the concentration of the colloidal absorbing particles in the ultrapure water to obtain the interception distribution of the colloidal absorbing particles in the flow-type composite absorbing material in the unsaturated porous medium.

[0075] It is worth noting that the process of performing column migration test on the absorbing material without adding thickener is basically the same as the process of performing column migration test on the flowable composite absorbing material prepared by the present invention as described above, and will not be described in detail here.

[0076] By conducting column migration tests on the absorbing material without thickener and the flowable composite absorbing material prepared by the present invention, it was found that Figure 3 The permeation curves of the flowable composite absorber and the absorber without thickener after column migration test, and Figure 4 The retained particle mass distribution diagram of the flowable composite absorbing material and the absorbing material without adding thickener after the column migration test.

[0077] It should be noted that the thickener added to the flowable composite absorbing material used in the test is specifically carboxymethyl cellulose, namely CMC. Figure 3 and Figure 4 In the figure, "WBW" represents the absorbing material without adding thickener, and "WBW+CMC" represents the flowable composite absorbing material prepared by the present invention. Figure 3 The “C / C0” shown on the vertical axis represents the relative concentration of the colloidal absorbing particles in the absorbing material in the unsaturated porous medium.

[0078] Reference Figure 3It can be seen that compared with the absorbing material without adding thickener, the flowable composite material prepared by the present invention with added CMC has stronger permeability in unsaturated porous media, which proves that CMC can effectively improve the permeability of the absorbing material when penetrating unsaturated porous media. Specifically, if the colloidal absorbing particles prepared in step S1 are directly dispersed in ultrapure water to prepare the absorbing material without adding thickener, the colloidal absorbing particles can hardly be detected in the leachate flowing out from the bottom of the organic glass column, which indicates that the absorbing material without adding thickener cannot make the colloidal absorbing particles effectively penetrate in the unsaturated porous medium. On the contrary, the flowable composite absorbing material prepared by adding CMC in the present invention has a significantly improved permeability of the colloidal absorbing particles in the unsaturated porous medium, wherein, after the pore volume (i.e., the permeation volume) reaches 20ml, the colloidal absorbing particles can basically flow out close to 100%.

[0079] Reference Figure 4 It can be seen from the retained particle mass distribution diagram that the colloidal absorbing particles in the absorbing material without adding thickener are mostly accumulated within 8 cm of the surface layer of the unsaturated porous medium, and the colloidal absorbing particles in the absorbing material without adding thickener are distributed very unevenly in the unsaturated porous medium. On the contrary, in the flowable composite absorbing material prepared by adding CMC in the present invention, the retained distribution of the colloidal absorbing particles in the unsaturated porous medium is quite uniform.

[0080] In addition, the inventors of the present invention also conducted a column migration test on the flowable composite absorbing materials with different added CMC concentrations to study the effects of different CMC concentrations on the prepared flowable composite absorbing materials.

[0081] Specifically, by conducting a column migration test on the flowable composite absorbing material with different CMC concentrations prepared by the present invention, it was obtained that Figure 5 The permeation curves of the flowable composite absorber with different CMC concentrations after column migration test, and Figure 6 The mass distribution of retained particles after column migration test of flowable composite absorbent materials with different CMC concentrations is shown. Figure 5 and Figure 6 In the figure, "CMC500", "CMC1000" and "CMC2000" represent flowable composite absorbers with CMC concentrations of 500 mg / L, 1000 mg / L and 2000 mg / L respectively. Figure 5 The “C / C0” shown on the vertical axis represents the relative concentration of the colloidal absorbing particles in the absorbing material in the unsaturated porous medium.

[0082] Reference Figure 5 and Figure 6 It can be seen that when the added CMC concentration is 500 mg / L, the penetration and interception distribution capabilities of the colloidal absorbing particles in the flowable composite absorbing material are similar to those of the absorbing material without adding thickener, showing the characteristics of less outflowing colloidal absorbing particles and uneven interception distribution of colloidal absorbing particles; correspondingly, when the added CMC concentration is 1000 mg / L, the penetration and interception distribution capabilities of the colloidal absorbing particles in the flowable composite absorbing material are improved; when the added CMC concentration is 2000 mg / L, the penetration and interception distribution capabilities of the colloidal absorbing particles in the flowable composite absorbing material reach an ideal level, and after the pore volume reaches 10 ml, the colloidal absorbing particles can basically flow out close to 100%, and the interception distribution in the unsaturated porous medium is uniform.

[0083] It can be seen that when actually preparing the flowable composite absorbing material disclosed in the present invention, the added CMC concentration can be controlled at about 2000 mg / L, so that the colloidal absorbing particles in the prepared flowable composite absorbing material have relatively ideal penetration and interception distribution capabilities.

[0084] In addition, it is worth mentioning that for the two types of unsaturated porous media, quartz sand and sandy soil, at the same volume, sandy soil has a larger mass and a smaller void volume than quartz sand. Although the water infiltration rate of sandy soil is roughly the same as that of quartz sand, sandy soil is less conducive to the penetration of colloidal absorbing particles in the flowable composite absorbing material. Therefore, for sandy soil and similar unsaturated porous media, the penetration capacity of the colloidal absorbing particles can be improved by further increasing the viscosity of the flowable composite absorbing material.

[0085] In addition, in order to verify the effectiveness of the flowable composite absorbing material prepared by the present invention in repairing soil containing PAHs, the inventors of the present invention also conducted an experiment on repairing soil containing PAHs using the flowable composite absorbing material. The soil containing PAHs used in the experiment of the present invention is sandy soil containing PAHs.

[0086] In addition, the inventors of the present invention also used flowable composite absorbing materials with glycerol added and absorbing materials without glycerol added as test objects, and conducted tests on repairing soil containing PAHs to verify the effect of glycerol on the flowable composite absorbing materials.

[0087] The above-mentioned absorbing material without glycerol addition can be understood as the absorbing material prepared by omitting the step of adding glycerol in the above-mentioned step S2.

[0088] Specifically, the test process for repairing soil containing PAHs using the flowable composite absorbing material disclosed in the embodiment of the present invention is as follows: add an appropriate amount of the flowable composite absorbing material to the top of the soil to be repaired, and let it stand to wait for the flowable composite absorbing material to naturally penetrate all the soil by gravity. Subsequently, a microwave emission source is inserted into the soil, wherein the microwave conditions are: irradiation power of 600W; irradiation time of 20min. Thereafter, the residual concentration and removal rate of PAHs in the soil are analyzed by ultrasonic extraction-high performance liquid chromatography.

[0089] The test of repairing soil containing PAHs by using the absorbing material without adding glycerol is basically the same as the process of testing the flowable composite absorbing material prepared by the present invention as described above, and will not be described in detail here.

[0090] Table 1 shows the restoration results of PAHs-containing soil after restoration by a flowable composite absorbing material with glycerol added and an absorbing material without glycerol added. In Table 1, "WBW+CMC" represents an absorbing material without glycerol added, and "WBW+CMC+GLY" represents a flowable composite absorbing material with glycerol added.

[0091] Table 1 The results of repairing soil containing PAHs by using flowable composite absorbent materials with glycerol added and absorbent materials without glycerol added

[0092]

[0093] As can be seen from Table 1, compared with the absorbing material without glycerol, the flowable composite absorbing material with glycerol added has a faster penetration rate in the soil, indicating that the addition of glycerol can effectively increase the penetration rate of the flowable composite absorbing material in the soil. In particular, when the added CMC concentration remains unchanged, only 1g / L of glycerol is added to increase the penetration rate of the flowable composite absorbing material in the soil from 0.285cm / min to 0.627cm / min.

[0094] At the same time, by adding glycerol as a polar substance to the flowable composite absorbing material, the removal rate of the three PAHs in the soil, naphthalene, fluorene and pyrene, was greatly improved when the flowable composite absorbing material with glycerol added was used to repair the soil containing PAHs, and the removal rate of the total amount of PAHs was also increased from 51.9% to 82.2%. This proves that by adding glycerol, the absorbing performance of the flowable composite absorbing material can be further improved, thereby improving the repair effect of the flowable composite absorbing material when repairing the soil containing PAHs.

[0095] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a flow-type composite absorbing material with in-situ seepage distribution, characterized in that: The following steps are involved: Step S1. Using agricultural and forestry waste as raw materials, preparing colloidal absorbing particles; Step S2. Dispersing the colloidal absorbing particles obtained in step S1 into a viscous aqueous solution containing a thickener, and adding glycerol to obtain a flowable composite absorbing material; The step S1 specifically includes: Step S11. Pre-treating the agricultural and forestry waste to obtain agricultural and forestry waste particles of a predetermined mesh size; Step S12. Soaking the agricultural and forestry waste particles obtained in step S11 in a FeSO4 solution, filtering after soaking, drying the filtrate after filtering, and calcining the filtrate after drying to obtain a powdered absorbing material; Step S13. Grinding the powdered absorbing material obtained in step S12, and separating the powdered absorbing material of a predetermined particle size by ultrasonic static method after grinding; Step S14. Mixing the powdered absorbing material of the predetermined particle size separated in step S13 with ultrapure water, and subjecting the mixture to water bath ultrasound to obtain a suspension; then allowing the suspension to stand, and then filtering the suspension through a filter membrane, drying the filter membrane after filtration, and finally obtaining the powder on the dried filter membrane as colloidal absorbing particles; In step S11, the process of pre-treating the agricultural and forestry waste to obtain agricultural and forestry waste particles of a predetermined mesh size is: washing, drying, crushing and screening the agricultural and forestry waste in sequence to obtain agricultural and forestry waste particles of a predetermined mesh size; Among them, the predetermined mesh size of agricultural and forestry waste particles is 20 meshes.

2. The method for preparing a flow-type composite absorbing material with in-situ seepage distribution according to claim 1, characterized in that: In step S12, the concentration of the FeSO4 solution is 0.3-0.5 mol / L, and the agricultural and forestry waste particles are immersed in the FeSO4 solution for 1 hour.

3. The method for preparing a flow-type composite absorbing material with in-situ seepage distribution according to claim 1, characterized in that: In the step S12, the specific process of calcining the dried filtrate is as follows: compacting the dried filtrate and placing it in a ceramic crucible, sealing the ceramic crucible and placing it in a muffle furnace for calcination; The calcination temperature in the muffle furnace is 550-650°C, the calcination time is 2.5-3.5h, and the heating rate is 5-10°C / min.

4. The method for preparing a flow-type composite absorbing material with in-situ seepage distribution according to claim 1, characterized in that: In the step S13, the particle size of the powdered absorbing material separated by the ultrasonic static method is less than 10 μm; In step S14, the ratio of the powdered absorbing material with a predetermined particle size to ultrapure water is 1:100; the water bath ultrasound is performed for 30 minutes; the suspension is allowed to stand for 1 hour; and the filter membrane used for filtration is a 0.45 μm mixed fiber resin filter membrane.

5. The method for preparing a flow-type composite absorbing material with in-situ seepage distribution according to claim 1, characterized in that: In the step S2, the viscous aqueous solution containing the thickener is obtained by dissolving the thickener in ultrapure water; Wherein, the mass ratio of thickener to ultrapure water is: (2g-3g): (100ml-200ml); Wherein, the thickener is carboxymethyl cellulose, xanthan gum or guar gum.

6. The method for preparing a flow-type composite absorbing material with in-situ seepage distribution according to claim 1, characterized in that: In step S2, the volume ratio of the mass of the colloidal absorbing particles, the mass of glycerol and the viscous aqueous solution is: (1g-3g): (1g-3g): (100ml-200ml).

7. A flow-type composite absorbing material with in-situ seepage distribution, characterized in that: The composite absorber is prepared by the method for preparing a flow-type composite absorber with in-situ seepage distribution as claimed in any one of claims 1 to 6.

8. Application of the flow-type composite absorbing material with in-situ seepage distribution as claimed in claim 7 in the field of microwave absorption.

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