A method for removing OCPs from soil based on surface expansion and elution

Abstract

The present invention discloses a method for removing OCPs in soil based on surface volume expansion and elution, comprising the following steps: step 1, plowing the soil to be treated, and sprinkling a volume expansion polarity-composite eluent into the soil while plowing; step 2, arranging and inserting electromagnetic rods according to the soil area, and connecting each electromagnetic rod to a control box; step 3, by alternately opening each electromagnetic rod to construct an alternating variable magnetic field in the soil, step 4, determining the content of organochlorine pesticides in the soil, and when meeting the soil remediation standard, stirring the electromagnetic rod while plowing to suck out the solids in the volume expansion polarity-composite eluent. The method of the present invention carries out the remediation treatment of organochlorine pesticide pollution in soil based on surfactant volume expansion, constructs a rod-shaped or capsule-shaped solid of "volume expansion" and "polarity", which can significantly improve the remediation effect of organochlorine pesticide-contaminated soil.

Description

Technical Field

[0001] The present invention relates to the technical field of organochlorine soil remediation, and in particular to a method for removing OCPs in soil based on surface volume expansion and elution. Background Art

[0002] Organochlorine pesticides (OCPs) are organic compounds used to control plant diseases and insect pests, containing the element organochlorine. The residue and accumulation of these pesticides in soil can cause a range of environmental and ecological hazards. First, organochlorine pesticides decompose slowly in soil. After prolonged use, they accumulate and contaminate the soil. This contamination not only affects soil fertility but can also lead to a decline in soil microbial and biodiversity, disrupting the soil's ecological balance.

[0003] Secondly, organochlorine pesticide residues can seep through the soil into groundwater or surface water, polluting water resources. This not only affects water quality but can also harm aquatic life, potentially leading to species extinction. Furthermore, organochlorine pesticides pose a potential threat to human health. If organochlorine pesticide residues remain in crops and enter the human body through the food chain, they can cause chronic toxic effects, impacting the nervous and endocrine systems. The potential risk is particularly high for sensitive populations such as children and pregnant women.

[0004] The remediation and treatment of soil contaminated by organochlorine pesticides has always been a technical issue that needs to be optimized in related industries. Since the existing elution and leaching technologies still have problems such as low removal rate, in order to reduce the hazards of organochlorine pesticides in the soil, it is now necessary to optimize and improve the remediation and treatment methods of OCPs in the soil. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for removing OCPs in soil based on surface volume expansion and elution.

[0006] The technical solution of the present invention is: a method for removing OCPs in soil based on surface volume expansion and elution, comprising the following steps:

[0007] Step 1: ploughing the soil to be treated, while sprinkling the soil with a volume-enhancing polar-composite eluent, so that the volume-enhancing polar-composite eluent moistens the soil and the solids in the volume-enhancing polar-composite eluent are evenly distributed in the soil;

[0008] Step 2: Arrange and insert electromagnetic rods according to the soil area, inserting 1 to 3 electromagnetic rods per square meter of soil, and connect each electromagnetic rod to the control box;

[0009] Step 3: Alternately turn on each electromagnetic rod to build an alternating variable magnetic field in the soil, and use a polarity-composite eluent to enhance the removal of organochlorine pesticides in the soil.

[0010] Step 4: Determine the content of organochlorine pesticides in the soil. When the soil meets the soil remediation standards, plow and stir the electromagnetic rod while sucking out the solids in the polar-composite eluent.

[0011] Furthermore, the compatibilized polar-composite eluent is obtained by mixing a solid substance and a Triton X-100 aqueous solution in a mass ratio of 1:3 to 5;

[0012] The solid material is composed of a matrix, a magnetic material attached to one end of the matrix, and a surfactant attached to the other end of the matrix. The matrix is ​​rod-shaped activated carbon fiber or capsule-shaped activated carbon fiber.

[0013] Description: Based on the principle of surfactant volume expansion and combined with magnetic materials, this invention constructs a "volume-increasing" and "polar" rod-shaped or capsule-shaped solid. By mixing it with a certain amount of Triton X-100 aqueous solution, it can significantly improve the remediation effect of organochlorine pesticide-contaminated soil.

[0014] By adsorbing surfactant molecules on activated carbon fibers, not only can a molecular layer coverage be formed, changing the surface tension of the fibers and making them easier to disperse, but the surfactants and activated carbon fibers can also work together to efficiently adsorb organochlorine pesticides in the soil.

[0015] Furthermore, the preparation method of the solid is:

[0016] S1. Preparation of a compatibilizing liquid: mixing a surfactant and water in a mass ratio of 1 to 2:10 to obtain a compatibilizing liquid;

[0017] S2. Preparation of polar liquid: dissolving chitosan in ferric chloride solution to obtain a polar liquid, wherein the mass molar ratio of chitosan to ferric chloride is 0.5-1.2 g / mmol, and the concentration of the ferric chloride solution is 0.2 mol / L;

[0018] S3. Pretreatment of the substrate: The middle portion of the substrate is clamped into the clamping hole of the carrier plate, and the two sides of the carrier plate are marked with side A and side B. The substrate on the A side of the carrier plate is then immersed in a nitric acid solution for 1-2 minutes, then rinsed with deionized water and dried in the shade;

[0019] S4. Preparation of solid matter:

[0020] S401, Side A Attachment: Manipulate the carrier plate so that the substrate on Side A is immersed in the compatibilizing liquid and stirred for 10-20 seconds, then removed from the compatibilizing liquid and irradiated with an infrared lamp for 3-5 seconds. Repeat the immersion and removal 8-12 times to complete the attachment of the surfactant to one end of the substrate.

[0021] S402, B-side attachment: Manipulate the carrier plate so that the substrate on the B side is immersed in the polar liquid. At the same time, add ferroferric oxide powder to the polar liquid according to the mass ratio of ferroferric oxide to chitosan of 1 to 2:1. Stir continuously for 10 to 20 seconds, then remove it from the polar liquid and irradiate it with an infrared lamp for 3 to 5 seconds. Repeat the immersion and removal 8 to 12 times to complete the attachment of the magnetic material on one end of the substrate.

[0022] Description: The present invention provides a preparation method for the constructed "capacitated" and "polar" rod-shaped or capsule-shaped solid. By using a carrier plate as an attachment control carrier at both ends of the substrate, the method is easy to operate and has high preparation efficiency. Different specifications of the carrier plate can be selected according to the production scale.

[0023] The surfactant molecules are adsorbed on the A side of the substrate using a compatibilizing liquid. After repeated "immersion-removal" and irradiation with a baking lamp, the surfactant molecules can be more evenly attached to the A side of the substrate and form a multi-layer molecular coverage.

[0024] At the same time, chitosan iron molecules contain a large number of hydroxyl groups and amino groups, which can bind to Fe on the surface of Fe3O4. 3+ As well as the oxygen-containing groups on the surface of the activated carbon, and under multiple "immersion-removal" and baking lamp irradiation, the magnetic material can be more evenly attached to the B side of the rod-shaped activated carbon fiber or the capsule-shaped activated carbon fiber, thereby improving the synergistic effect with the alternating variable magnetic field.

[0025] Furthermore, the surfactant is one of polysorbate or sodium dodecylbenzenesulfonate.

[0026] Description: Polysorbate has low surface tension and good permeability, and has excellent stability, while sodium dodecylbenzene sulfonate has excellent cleaning performance. Its molecular structure is hydrophilic and lipophilic, it is not easy to oxidize and has good stability. Based on surfactant capacity expansion, the above molecules are adsorbed on the surface of activated carbon fiber, which enables the surfactant and activated carbon fiber to synergize with each other to efficiently adsorb organochlorine pesticides in the soil.

[0027] Furthermore, the content of Triton X-100 in the Triton X-100 aqueous solution is 80 to 120 g / L.

[0028] Description: Triton X-100 molecules contain hydrophilic ether groups that do not dissociate in aqueous solution. Its surface activity is manifested by neutral molecules. Through micelle solubilization and significantly reducing the surface tension of the water-soil interface, it destroys the hydrophobic surface and reduces the polarity of organic pollutant molecules, thereby promoting the desorption of hydrophobic organochlorine pesticides from the surface of soil particles and increasing their water solubility.

[0029] Compared with other surfactants, Triton X-100 can significantly increase the dissolution rate of persistent organic pollutants (POPs), which are insoluble compounds tightly bound to soil particles, promote the effective contact between insoluble compounds and oxidants in the soil, and increase remediation efficiency.

[0030] At the same time, Triton X-100 is not easily affected by the presence of strong electrolytes, nor is it easily affected by acids and alkalis. It can be mixed with other types of surfactants, has good compatibility, has good solubility in various solvents, does not undergo strong adsorption on solid surfaces, and is non-toxic, non-irritating, and has good biodegradability. By using the Triton X-100 aqueous solution with the above ratio, it can ensure that water fully moistens the soil, thereby promoting the remediation of soil contaminated by organochlorine pesticides.

[0031] Furthermore, the mass ratio of the amount of the expanded polar-composite eluent to the soil to be treated is 2 to 3:1.

[0032] Note: By using the above-mentioned mass ratio of the expanded polar-composite eluent for soil drench, the remediation effect of organochlorine pesticide-contaminated soil is guaranteed while avoiding excessive use of the agent and the increase in remediation costs.

[0033] Furthermore, the alternating variable magnetic field is: taking each square meter of soil as a reference point, ensuring that the electromagnetic rods at adjacent reference points are turned on alternately, the alternating turning-on time is 10 to 20 minutes, each electromagnetic rod is turned on for 4 to 6 hours a day, and the magnetic field strength generated by a single electromagnetic rod is 8000 to 15000G.

[0034] Description: By adopting the above-mentioned alternating variable magnetic field configuration control, the solids in the polarity-composite eluent can be deflected or offset under the action of the alternating variable magnetic field, which can promote the synergistic interaction between the surfactant in the solids and the activated carbon fiber to efficiently adsorb organochlorine pesticides in the soil;

[0035] Through practical application, it was found that by extending the daily opening time of the electromagnetic rod on the above basis, the efficient adsorption of organochlorine pesticides in the soil was reduced. The use of the above-mentioned alternating variable magnetic field can ensure stable remediation of organochlorine pesticide-contaminated soil, and it is low-consumption and energy-saving, and reasonably controls the remediation cost.

[0036] Furthermore, the specific arrangement of inserting 1 to 3 electromagnetic rods per square meter of soil is as follows:

[0037] 1) When one electromagnetic rod is inserted into each square meter of soil, the electromagnetic rod is set at the geometric midpoint of the area;

[0038] 2) When two electromagnetic rods are inserted into each square meter of soil, the electromagnetic rods are set at two geometrically diagonal points of the area, and the arrangement positions of the electromagnetic rods inserted into each square meter of soil are the same;

[0039] 3) When three electromagnetic rods are inserted into each square meter of soil, the electromagnetic rods are arranged at two geometrically diagonal points and a geometric midpoint of the area, and the arrangement positions of the electromagnetic rods inserted into each square meter of soil are the same.

[0040] Description: The number of electromagnetic rods inserted per square meter of soil is used for regional arrangement, which can make the electromagnetic rods evenly distributed in the soil area to be treated, and facilitate the control of each electromagnetic rod using a control box, thereby constructing a stable alternating variable magnetic field to coordinate the remediation of soil contaminated by organochlorine pesticides.

[0041] Furthermore, the tillage depth of the soil in step 1 and step 4 is 30 to 50 cm; the insertion depth of the electromagnetic rod in step 2 is 40 to 60 cm.

[0042] Note: The tillage depth can be adjusted according to the contamination depth of the soil to be treated. It is not limited to the above tillage depth. As for the insertion depth of the electromagnetic rod, considering the looseness of the soil after tillage, the insertion depth is about 10 cm deeper than the tillage depth, which helps to improve the layout stability of the electromagnetic rod.

[0043] The beneficial effects of the present invention are:

[0044] The method of the present invention is based on surfactant volume expansion to carry out remediation treatment of organochlorine pesticide pollution in soil. On this basis, a "volume-increasing" and "polar" rod-shaped or capsule-shaped solid is constructed, and by compounding and mixing with a certain amount of Triton X-100 aqueous solution, the remediation effect of organochlorine pesticide-contaminated soil can be significantly improved. At the same time, an alternating variable magnetic field is applied by using related electromagnetic rods. The alternating variable magnetic field cooperates with the rod-shaped or capsule-shaped solid to adsorb the organochlorine pesticide pollution in the soil, which can significantly shorten the remediation time of organochlorine pesticide-contaminated soil, thereby providing a new remediation treatment method for remediation of organochlorine pesticide-contaminated soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a process flow chart of the method of the present invention.

[0046] Figure 2 It is a schematic diagram of the arrangement in which one electromagnetic rod is inserted into every square meter of soil in the method of the present invention.

[0047] Figure 3 It is a schematic diagram of the arrangement of inserting two electromagnetic rods into each square meter of soil in the method of the present invention.

[0048] Figure 4 It is a schematic diagram of the arrangement of inserting three electromagnetic rods into each square meter of soil in the method of the present invention.

[0049] Figure 5 It is a schematic diagram of the A-side attachment in the method of the present invention.

[0050] Figure 6 3 is a histogram of pollutant removal rates for Examples 1-3 of the present invention and the control.

[0051] Figure 7 4-5 of the present invention and the control of the pollutant removal rate histogram.

[0052] Figure 8 3 is a histogram of pollutant removal rates for Examples 6-7 of the present invention and the control.

[0053] Figure 9 is a histogram of pollutant removal rates for Examples 8-19 of the present invention. DETAILED DESCRIPTION

[0054] The present invention will be further described in detail below in conjunction with specific implementation methods to better demonstrate the advantages of the present invention.

[0055] Example 1:

[0056] like Figure 1 As shown, a method for removing OCPs in soil based on surface expansion and elution comprises the following steps:

[0057] Step 1: ploughing the soil to be treated to a depth of 40 cm, while sprinkling the soil with a volume-enhancing polar-composite eluent, wherein the mass ratio of the volume-enhancing polar-composite eluent to the soil to be treated is 5:2; the volume-enhancing polar-composite eluent moistens the soil and the solids in the volume-enhancing polar-composite eluent are evenly distributed in the soil;

[0058] It is understood that the tillage depth is adjusted according to the contamination depth of the soil to be treated and is not limited to the above depth conditions;

[0059] Step 2: Arrange and insert the electromagnetic rods according to the soil area, such as Figure 3 As shown, two electromagnetic rods are inserted into each square meter of soil with an insertion depth of 50 cm. The electromagnetic rods are set at two geometrically diagonal points of the area, and the arrangement positions of the electromagnetic rods inserted into each square meter of soil are the same. Each electromagnetic rod is connected to a control box.

[0060] It is understandable that the electromagnetic rod is a commercially available electromagnetic rod with a diameter of 5 cm, and the insertion depth of the electromagnetic rod is adjusted according to the contamination depth of the soil to be treated. However, in theory, the insertion depth is 10 cm deeper than the plowing depth, which helps to improve the layout stability of the electromagnetic rod. At the same time, the control box uses a commercially available distribution box with a programmable controller.

[0061] Step 3: Alternately activate each electromagnetic rod to construct an alternating variable magnetic field in the soil. Each square meter of soil is used as a reference point. Ensure that the electromagnetic rods at adjacent reference points are alternately activated. The alternating activation time is 15 minutes. Each electromagnetic rod is activated for 5 hours per day. The magnetic field strength generated by a single electromagnetic rod is 13,000 G. A polarity-composite eluent is used to enhance the removal of organochlorine pesticides in the soil.

[0062] Step 4: Determine the content of organochlorine pesticides in the soil. When the soil meets the soil remediation standards, plow and stir the electromagnetic rod while sucking out the solids in the polar-composite eluent.

[0063] The compatibilized polar-composite eluent is prepared by mixing a solid substance and a Triton X-100 aqueous solution in a mass ratio of 1:4. The solid substance is composed of a matrix, a magnetic material attached to one end of the matrix, and a surfactant attached to the other end of the matrix. The matrix is ​​encapsulated activated carbon fiber, and the surfactant is sodium dodecylbenzene sulfonate.

[0064] The preparation method of the solid is:

[0065] S1. Preparation of a compatibilizing liquid: mixing a surfactant and water in a mass ratio of 3:20 to obtain a compatibilizing liquid;

[0066] S2. Preparation of polar liquid: dissolving chitosan in ferric chloride solution to obtain a polar liquid, wherein the mass molar ratio of chitosan to ferric chloride is 1.1 g / mmol, and the concentration of the ferric chloride solution is 0.2 mol / L;

[0067] S3. Pretreatment of the substrate: The middle portion of the substrate is clamped into the clamping hole of the carrier plate, and the two sides of the carrier plate are marked with side A and side B. The substrate on the A side of the carrier plate is then immersed in a nitric acid solution with a mass concentration of 30% for 2 minutes, and then rinsed with deionized water and dried in the shade;

[0068] S4. Preparation of solid matter:

[0069] S401, A side attachment: Figure 5 As shown, the carrier plate was manipulated so that the substrate on side A was immersed in the compatibilizing liquid and stirred for 15 seconds, then taken out of the compatibilizing liquid and irradiated with an infrared lamp for 4 seconds. The immersion and removal were repeated 10 times to complete the attachment of the surfactant on one end of the substrate.

[0070] S402, B side attachment: same Figure 5 As shown, the carrier plate is manipulated so that the substrate on the B side is immersed in the polar liquid. At the same time, ferroferric oxide powder is added to the polar liquid according to the mass ratio of ferroferric oxide to chitosan of 3:2. The mixture is stirred for 15 seconds, then removed from the polar liquid and irradiated with an infrared lamp for 4 seconds. The immersion and removal are repeated 10 times to complete the attachment of the magnetic material to one end of the substrate.

[0071] It is understandable that the infrared baking lamp is selected from a commercially available heating lamp, and the heating temperature is 120°C.

[0072] The content of Triton X-100 in the Triton X-100 aqueous solution is 100 g / L.

[0073] Example 2: This example differs from Example 1 in that the mass ratio of the amount of the expanded polar-composite eluent to the soil to be treated is 2:1.

[0074] Example 3: This example differs from Example 1 in that the mass ratio of the amount of the expanded polar-composite eluent to the soil to be treated is 3:1.

[0075] The above-mentioned method was used to conduct a soil OCPs removal test at an abandoned site of an organochlorine pesticide production enterprise in Changzhou City, Jiangsu Province. After testing, the concentrations of o,p'-DDT, α-HCH, and o-nitrochlorobenzene in the contaminated soil were 125.40±65.5 mg / kg, 150.03±55.4 mg / kg, and 117.38±63.3 mg / kg, respectively.

[0076] The plots were divided into 2 square meters each, and the tillage depth was 40 cm. The three indicators of o,p'-DDT, α-HCH, and o-nitrochlorobenzene in each plot were regulated as much as possible to maintain them at (125.40 mg / kg, 150.03 mg / kg, and 117.38 mg / kg), respectively. The contaminated soil was remediated using the methods of Example 1, Example 2, and Example 3, respectively, and the treatment was carried out for a period of 5 days.

[0077] The test soil was then extracted with a 1:1 hexane / acetone (volume ratio) on an accelerated solvent extractor (ASE-200, Dionex, USA) at 100°C and 1500 psi for 5 min. After three cycles of extraction, the extract was concentrated to 2 mL on a rotary evaporator (R-210, B-491, V-850, B741, BUCHI, Switzerland). The concentrate was then purified using a solid-phase extraction column (1 g anhydrous sodium sulfate + 1.5 g florisil + 1.5 g chromatography silica gel + 1 g anhydrous sodium sulfate) with a 98:2 hexane / acetone (volume ratio). The purified solution was collected and concentrated, then brought to 1 mL with hexane for analysis by GC. The results are shown in Table 1 below.

[0078] Table 1 Residual concentrations of pollutants after treatment of organochlorine pesticide contaminated soil

[0079]

[0080] Among them, the above control is not added with solids, and only the Triton X-100 aqueous solution is used for treatment, and the other parameters are the same as those in Example 1; at the same time, Figure 6 As shown, according to the histogram, it can be seen that the pollutant removal rates of Example 1, Example 2, and Example 3 are roughly between 96% and 98%, specifically:

[0081] The pollutant removal rate of Example 1 was 98.23%; the pollutant removal rate of Example 2 was 96.42%; the pollutant removal rate of Example 3 was 98.52%; and the pollutant removal rate of the control was 79.40%.

[0082] This shows that the use of a capacitated polar-composite eluent for soil pollutant removal has a more significant effect. By adding solids and an alternating variable magnetic field, the "capacitated" and "polar" rod-shaped or capsule-shaped solid can be constructed to efficiently adsorb soil pollutants under the action of an alternating variable magnetic field, and the adsorption effect is enhanced by the synergistic effect of surfactants and activated carbon fibers.

[0083] At the same time, by observing the histogram, it can be roughly seen that the pollutant removal rate of Example 3 is roughly the same as that of Example 1, and Example 3 uses a larger dose of the volume-enhancing polar-composite eluent. From an economic point of view, the use of a relatively small dosage can effectively reduce the cost of repair treatment.

[0084] The following embodiments are for adjusting the number and position of electromagnetic rods:

[0085] Example 4: This example differs from Example 1 in that the electromagnetic rods are inserted according to the soil area. Figure 2As shown, one electromagnetic rod is inserted into each square meter of soil and is set at the geometric midpoint of the area.

[0086] Example 5: This example differs from Example 1 in that the electromagnetic rods are inserted according to the soil area. Figure 4 As shown, three electromagnetic rods are inserted into each square meter of soil. The electromagnetic rods are arranged at two geometric diagonal points and a geometric midpoint of the area, and the arrangement positions of the electromagnetic rods inserted into each square meter of soil are the same.

[0087] The experimental methods of Examples 1-3 were used to study and analyze the number and position adjustment of the electromagnetic rods. The results were as follows: Figure 7 As shown:

[0088] At the same time, a control was set up. Based on Example 1, two electromagnetic rods were respectively arranged at the geometric adjacent corners of the area, and the arrangement positions of the electromagnetic rods inserted in each square meter of soil were the same, as shown in FIG. Figure 7 As shown, according to the histogram, it can be seen that the pollutant removal rates of Example 4 and Example 5 are roughly between 94% and 98%, specifically:

[0089] The pollutant removal rate of Example 4 is 94.22%; the pollutant removal rate of Example 5 is 98.79%; the pollutant removal rate of the control is 90.14%.

[0090] It can be seen that inserting more electromagnetic rods per unit area of ​​contaminated soil can further enhance the synergistic auxiliary effect on the volume-enhancing polarity-composite eluent to a certain extent. At the same time, after using different arrangement methods, it can be found that the pollutant removal rate has decreased significantly. This may be because the alternating variable magnetic field distribution of the control type has a relatively weak magnetic effect on the solids in the volume-enhancing polarity-composite eluent, which may be related to its uneven distribution. At the same time, through comparison, it is found that the effect of Example 5 is better than that of Example 1, but the relative power consumption is increased, and it can be selected according to actual treatment requirements.

[0091] The following embodiment is for adjusting parameters of the alternating variable magnetic field:

[0092] Example 6: The difference between this example and Example 1 is that an alternating variable magnetic field in the soil is constructed by alternately turning on each electromagnetic rod. Each square meter of soil is used as a reference point to ensure that the electromagnetic rods at adjacent reference points are turned on alternately. The alternating turning-on time is 10 minutes, and each electromagnetic rod is turned on for 4 hours a day. The magnetic field strength generated by a single electromagnetic rod is 8000G.

[0093] Example 7: The difference between this example and Example 1 is that an alternating variable magnetic field in the soil is constructed by alternately turning on each electromagnetic rod. Each square meter of soil is used as a reference point to ensure that the electromagnetic rods at adjacent reference points are turned on alternately. The alternating turning-on time is 20 minutes, and each electromagnetic rod is turned on for 6 hours a day. The magnetic field strength generated by a single electromagnetic rod is 15000G.

[0094] The experimental method of Examples 1-3 was used to conduct the above-mentioned parameter adjustment of the alternating variable magnetic field, and the measurement results were as follows: Figure 8 As shown:

[0095] At the same time, a control was set up, with Example 1 as the benchmark, without applying the alternating variable magnetic field, such as Figure 8 As shown, according to the histogram, it can be seen that the pollutant removal rates of Example 6 and Example 7 are roughly between 95% and 97%, specifically:

[0096] The pollutant removal rate of Example 6 was 95.62%; the pollutant removal rate of Example 7 was 97.79%; and the pollutant removal rate of the control was 87.53%.

[0097] It can be seen that after the alternating variable magnetic field is removed, the pollutant removal rate decreases significantly, and the solids of the volume-enhancing polarity-composite eluent lose the effect of the alternating variable magnetic field, making it impossible for them to be deflected or offset. Therefore, there is a synergistic auxiliary effect on the volume-enhancing polarity-composite eluent when the alternating variable magnetic field is applied; at the same time, through comparison, it is found that after continuously increasing the magnetic field strength of a single electromagnetic rod, the pollutant removal rate decreases to a certain extent. This may be because the increase in magnetic field strength causes the solids to deviate too much, and the distribution of solids in the soil becomes irreversibly uneven, thereby destroying the uniform distribution of the solids and affecting the solid remediation treatment effect to a certain extent.

[0098] The following examples are preparation adjustments of the compatibilized polar-composite eluent:

[0099] Example 8: This example is different from Example 1 in that the compatibilized polar-composite eluent is obtained by mixing a solid substance and a Triton X-100 aqueous solution in a mass ratio of 1:3.

[0100] Example 9: This example is different from Example 1 in that the compatibilized polar-composite eluent is obtained by mixing a solid substance and a Triton X-100 aqueous solution in a mass ratio of 1:5.

[0101] Example 10: This example differs from Example 1 in that the surfactant and water are mixed in a mass ratio of 1:10 to obtain a compatibilizing liquid.

[0102] Example 11: This example differs from Example 1 in that the surfactant and water are mixed in a mass ratio of 2:10 to obtain a compatibilizing liquid.

[0103] Example 12: This example differs from Example 1 in that chitosan is dissolved in a ferric chloride solution to obtain a polar liquid, wherein the mass molar ratio of chitosan to ferric chloride is 0.5 g / mmol, the concentration of the ferric chloride solution is 0.2 mol / L, and when attached to the B side, ferrosoferric oxide powder is added to the polar liquid at a mass ratio of ferrosoferric oxide to chitosan of 1:1.

[0104] Example 13: This example differs from Example 1 in that chitosan is dissolved in a ferric chloride solution to obtain a polar liquid, wherein the mass molar ratio of chitosan to ferric chloride is 1.2 g / mmol, the concentration of the ferric chloride solution is 0.2 mol / L, and when attached to the B side, ferrosoferric oxide powder is added to the polar liquid at a mass ratio of ferrosoferric oxide to chitosan of 2:1.

[0105] Example 14: This example differs from Example 1 in that, for the attachment on side A, the carrier plate is manipulated so that the substrate on side A is immersed in the compatibilizing liquid and stirred for 10 seconds, then taken out of the compatibilizing liquid and irradiated with an infrared lamp for 3 seconds, and the immersion-removal is repeated 8 times to complete the attachment of the surfactant on one end of the substrate.

[0106] Example 15: The difference between this example and Example 1 is that, for the attachment on side A, the carrier plate is manipulated so that the substrate on side A is immersed in the compatibilizing liquid and stirred for 20 seconds, then taken out of the compatibilizing liquid and irradiated with an infrared lamp for 5 seconds, and the immersion-removal is repeated 12 times to complete the attachment of the surfactant on one end of the substrate.

[0107] Example 16: The difference between this example and Example 1 is that, in terms of attachment on the B side: the carrier plate is manipulated so that the substrate on the B side is immersed in the polar liquid, and at the same time, ferrosoferric oxide powder is added to the polar liquid in a mass ratio of ferrosoferric oxide to chitosan of 3:2, and the mixture is stirred for 10 seconds. The mixture is then taken out of the polar liquid and irradiated with an infrared lamp for 3 seconds. The immersion and removal process is repeated 8 times to complete the attachment of the magnetic material to one end of the substrate.

[0108] Example 17: The difference between this example and Example 1 is that, in terms of attachment on the B side: the carrier plate is manipulated so that the substrate on the B side is immersed in the polar liquid, and at the same time, ferrosoferric oxide powder is added to the polar liquid in a mass ratio of ferrosoferric oxide to chitosan of 3:2, and the mixture is stirred for 20 seconds. The mixture is then taken out of the polar liquid and irradiated with an infrared lamp for 5 seconds. The immersion and removal are repeated 12 times to complete the attachment of the magnetic material to one end of the substrate.

[0109] Example 18: This example differs from Example 1 in that the content of Triton X-100 in the Triton X-100 aqueous solution is 80 g / L.

[0110] Example 19: This example differs from Example 1 in that the content of Triton X-100 in the Triton X-100 aqueous solution is 120 g / L.

[0111] The experimental method of Example 1-3 was used to study and analyze the preparation and adjustment of the above-mentioned polar-composite eluent. The results were as follows: Figure 9 As shown:

[0112] At the same time, a control was set up, with Example 1 as the benchmark, without applying the alternating variable magnetic field, such as Figure 9 As shown, according to the bar chart, it can be seen that the pollutant removal rates of Examples 8 to 19 are roughly between 94% and 98%, specifically:

[0113] The pollutant removal rate of Example 8 is 98.37%; the pollutant removal rate of Example 9 is 94.65%; the pollutant removal rate of Example 10 is 97.46%; the pollutant removal rate of Example 11 is 98.29%; the pollutant removal rate of Example 12 is 97.82%; the pollutant removal rate of Example 13 is 98.13%; the pollutant removal rate of Example 14 is 97.67%; the pollutant removal rate of Example 15 is 98.37%; the pollutant removal rate of Example 16 is 97.53%; the pollutant removal rate of Example 17 is 98.41%; the pollutant removal rate of Example 18 is 96.56%; the pollutant removal rate of Example 19 is 98.35%;

[0114] It can be seen that the effects of using the polar-composite eluent at different ratios are different. As the proportion of solids increases, the effect of the polar-composite eluent is better. However, as the proportion of solids increases, the improvement effect gradually slows down. Therefore, the ratio can be selected as needed based on the cost of use and other factors.

[0115] At the same time, by comparing different ratios of compatibilizer and polar liquid, it can be seen that as the dosage increases, the prepared compatibilizer polar-composite eluent is not greatly affected. Considering multiple aspects such as removal effect and cost, the ratio of compatibilizer and polar liquid in Example 1 is relatively balanced.

[0116] By comparing the parameters of different A-side and B-side attachment treatments, it can be seen that Example 15 and Example 17 both have better performance than Example 1, but the improvement is not significant. Correspondingly, during the production process, the preparation time of Example 15 and Example 17 is longer. Therefore, the selection should be made according to actual production needs.

[0117] By comparing the proportions of different Triton X-100s, it can be seen that as the amount of Triton X-100 added gradually increases, it has a positive promoting effect on the pollutant removal rate, but its effect gradually slows down. Considering the purchase cost of Triton X-100, the capacity-enhancing polar-composite eluent formulated in Example 1 is relatively more economical.

Claims

1. A method for removing OCPs from soil based on surface volume expansion and elution, characterized in that: The following steps are involved: Step 1: ploughing the soil to be treated, while sprinkling the soil with a volume-enhancing polar-composite eluent, so that the volume-enhancing polar-composite eluent moistens the soil and the solids in the volume-enhancing polar-composite eluent are evenly distributed in the soil; Step 2: Arrange and insert electromagnetic rods according to the soil area. Insert 1 to 3 electromagnetic rods per square meter of soil and connect each electromagnetic rod to the control box. Step 3: Alternately turn on each electromagnetic rod to build an alternating variable magnetic field in the soil, and use a polarity-composite eluent to enhance the removal of organochlorine pesticides in the soil. Step 4: Determine the content of organochlorine pesticides in the soil. When the soil meets the soil remediation standards, plow and stir the electromagnetic rod while sucking out the solids in the polar-composite eluent. The compatibilized polar-composite eluent is obtained by mixing a solid substance and a Triton X-100 aqueous solution in a mass ratio of 1:3 to 5; The solid material is composed of a matrix, a magnetic material attached to one end of the matrix, and a surfactant attached to the other end of the matrix, and the matrix is ​​a rod-shaped activated carbon fiber or a capsule-shaped activated carbon fiber; The preparation method of the solid material is as follows: S1. Preparation of a compatibilizing liquid: mixing a surfactant and water in a mass ratio of 1 to 2:10 to obtain a compatibilizing liquid; S2. Preparation of polar liquid: dissolving chitosan in ferric chloride solution to obtain a polar liquid, wherein the mass molar ratio of chitosan to ferric chloride is 0.5-1.2 g / mmol, and the concentration of the ferric chloride solution is 0.2 mol / L; S3. Pretreatment of the substrate: The middle portion of the substrate is clamped into the clamping hole of the carrier plate, and the two sides of the carrier plate are marked with side A and side B. The substrate on the A side of the carrier plate is then immersed in a nitric acid solution for 1-2 minutes, then rinsed with deionized water and dried in the shade; S4. Preparation of solid matter: S401, Side A Attachment: Manipulate the carrier plate so that the substrate on Side A is immersed in the compatibilizing solution and stirred for 10-20 seconds, then removed from the compatibilizing solution and irradiated with an infrared lamp for 3-5 seconds. Repeat the immersion and removal 8-12 times to complete the attachment of the surfactant to one end of the substrate. S402, B-side attachment: Manipulate the carrier plate so that the substrate on the B side is immersed in the polar liquid. At the same time, add ferroferric oxide powder to the polar liquid according to the mass ratio of ferroferric oxide to chitosan of 1-2:

1. Stir continuously for 10-20 seconds, then remove from the polar liquid and irradiate with an infrared lamp for 3-5 seconds. Repeat the immersion-removal 8-12 times to complete the attachment of the magnetic material on one end of the substrate.

2. The method for removing OCPs in soil based on surface volume expansion and elution according to claim 1, characterized in that: The mass ratio of the surfactant to water is 1-2:10, and the surfactant is one of polysorbate or sodium dodecylbenzene sulfonate.

3. The method for removing OCPs in soil based on surface volume expansion and elution according to claim 1, characterized in that: The content of Triton X-100 in the Triton X-100 aqueous solution is 80-120 g / L.

4. The method for removing OCPs in soil based on surface volume expansion and elution according to claim 1, characterized in that: The mass ratio of the amount of the expanded polar-composite eluent to the soil to be treated is 2-3:

1.

5. The method for removing OCPs in soil based on surface volume expansion and elution according to claim 1, characterized in that: The alternating variable magnetic field is as follows: taking each square meter of soil as a reference point, the electromagnetic rods at adjacent reference points are alternately turned on, the alternating turning-on time is 10 to 20 minutes, each electromagnetic rod is turned on for 4 to 6 hours a day, and the magnetic field strength generated by a single electromagnetic rod is 8000 to 15000G.

6. The method for removing OCPs in soil based on surface expansion and elution according to claim 1, characterized in that: The specific arrangement of inserting 1 to 3 electromagnetic rods per square meter of soil is as follows: 1) When one electromagnetic rod is inserted into each square meter of soil, the electromagnetic rod is set at the geometric midpoint of the area; 2) When two electromagnetic rods are inserted into each square meter of soil, the electromagnetic rods are set at two geometrically opposite points of the area, and the arrangement positions of the electromagnetic rods inserted into each square meter of soil are the same; 3) When three electromagnetic rods are inserted into each square meter of soil, the electromagnetic rods are set at two geometrically diagonal points and a geometric midpoint of the area, and the arrangement positions of the electromagnetic rods inserted into each square meter of soil are the same.

7. The method for removing OCPs in soil based on surface volume expansion and elution according to claim 1, characterized in that: The tillage depth of the soil in step 1 and step 4 is 30-50 cm; the insertion depth of the electromagnetic rod in step 2 is 40-60 cm.

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