Method for removing OCPs in soil based on surface compatibilization elution

Abstract

The invention discloses a method for removing OCPs in soil based on surface compatibilization elution, which comprises the following steps: step 1, ploughing the soil to be treated, and spraying a compatibilization polar-compound eluting agent into the soil while ploughing; step 2, arranging and inserting electromagnetic rods according to the soil area, and connecting each electromagnetic rod to a control electric box; the method comprises the following steps of 1, preparing the compatibilization polar-composite eluting agent, 2, preparing the compatibilization polar-composite eluting agent, 3, constructing an alternating variable magnetic field in the soil by alternately opening each electromagnetic rod, and 4, determining the content of organochlorine pesticide in the soil, and sucking out solids in the compatibilization polar-composite eluting agent by stirring the electromagnetic rods while ploughing when the soil meets the soil remediation standard. According to the method disclosed by the invention, remediation treatment of organochlorine pesticide pollution in the soil is carried out based on compatibilization of the surfactant, a'compatibilized 'and'polar' rod-shaped or capsule-shaped solid is constructed, and the remediation effect of the organochlorine pesticide polluted soil can be remarkably improved.

Description

Technical Field

[0001] The 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, and their components contain organochlorine elements. The residue and accumulation of such pesticides in the soil will cause a series of harms to the environment and ecology. First of all, organochlorine pesticides decompose slowly in the soil. After long-term use, they will accumulate in the soil and cause soil pollution. This pollution not only affects the fertility of the soil, but may also lead to a decline in microorganisms and biodiversity in the soil, destroying the ecological balance of the soil.

[0003] Secondly, the residues of organochlorine pesticides will penetrate into groundwater or surface water through the soil, causing pollution to water resources. This not only affects the quality of water, but may also cause harm to aquatic organisms and even lead to the extinction of aquatic species. In addition, organochlorine pesticides also pose a potential threat to human health. If there are organochlorine pesticides left in crops, they may enter the human body through the food chain and cause chronic toxic effects on the human body, affecting the human nervous system, endocrine system, etc. Especially for sensitive groups such as children and pregnant women, the potential risk is even greater.

[0004] The remediation of soil contaminated by organochlorine pesticides has always been a technical issue that needs to be optimized in the relevant 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 methods of OCPs in the soil. Summary of the invention

[0005] In order 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, tilling the soil to be treated, while sprinkling the volume-increasing polar-composite eluent into the soil, so that the volume-increasing polar-composite eluent moistens the soil and the solids in the volume-increasing polar-composite eluent are evenly distributed in the soil;

[0008] 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;

[0009] Step 3: Alternately turn on each electromagnetic rod to build an alternating variable magnetic field in the soil, and use a capacitated 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, stir the electromagnetic rod while tilling to absorb the solids in the polar-composite eluent.

[0011] Furthermore, the volume-increasing 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, and the matrix is ​​rod-shaped activated carbon fiber or capsule-shaped activated carbon fiber.

[0013] Description: Based on the principle of surfactant capacity expansion and combined with magnetic materials, the present invention constructs a "capacitated" 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 soil contaminated by organochlorine pesticides.

[0014] By adsorbing surfactant molecules on activated carbon fibers, not only can a molecular layer coverage be formed to change the surface tension of the fibers, making them easier to disperse, but the surfactant 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 expansion liquid: mixing the surfactant and water in a mass ratio of 1 to 2:10 to obtain an expansion 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 part of the substrate is clamped into the clamping hole of the carrier, and the two sides of the carrier are marked with side A and side B, and then the substrate on the side A of the carrier is immersed in a nitric acid solution for 1 to 2 minutes, and then rinsed with deionized water and dried in the shade;

[0019] S4. Preparation of solid matter:

[0020] S401, A side attachment: manipulate the carrier plate so that the substrate on the A side is immersed in the expansion liquid and stirred for 10 to 20 seconds, then taken out from the expansion liquid and irradiated with an infrared lamp for 3 to 5 seconds, and the immersion-removal is repeated 8 to 12 times to complete the attachment of the surfactant on 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, and at the same time, ferroferric oxide powder is added to the polar liquid according to the mass ratio of ferroferric oxide to chitosan of 1 to 2:1, and stirred continuously for 10 to 20 seconds, then taken out from the polar liquid and irradiated with an infrared lamp for 3 to 5 seconds, and the immersion-removal is repeated 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, it is easy to operate and has high preparation efficiency. The carrier plate size of different specifications can be selected according to the production scale;

[0023] The surfactant molecules are adsorbed on the A side of the substrate using a compatibilizer, and under multiple "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 the 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 irradiation with a baking lamp, 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 dodecylbenzene sulfonate.

[0026] Description: Polysorbate has low surface tension and good permeability, and has excellent stability, while sodium dodecylbenzene sulfonate has excellent cleaning performance, and its molecular structure is hydrophilic and lipophilic, and 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 cooperate 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: The Triton X-100 molecule contains a hydrophilic ether group that does not dissociate in aqueous solution. Its surface activity is manifested by neutral molecules. It solubilizes through micelles and significantly reduces the surface tension of the water-soil interface, 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 insoluble compounds (persistent organic pollutants) that are tightly bound to soil particles, promote the effective contact between insoluble compounds and oxidants in the soil, and increase the 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 strongly adsorb 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 is possible to promote the remediation of soil contaminated by organochlorine pesticides under the premise of ensuring that water fully moistens the soil.

[0031] Furthermore, the mass ratio of the spraying amount of the volume-expanding 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 spraying, the remediation effect of organochlorine pesticide-contaminated soil can be guaranteed while avoiding excessive use of the agent and resulting in an 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 volume-increasing polarity-composite eluent can be deflected or offset under the action of the alternating variable magnetic field, which can promote the surfactant of the solids and the activated carbon fiber to cooperate with each other to efficiently adsorb and treat the 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 soil contaminated by organochlorine pesticides, and it is energy-saving and saves energy, 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 arranged 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 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.

[0040] Description: By arranging the area according to the number of electromagnetic rods inserted per square meter of soil, the electromagnetic rods can be evenly distributed in the soil area to be treated, and it is convenient to use a control box to control each electromagnetic rod, 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 the volume expansion of surfactants to carry out the remediation treatment of organochlorine pesticide pollution in soil. On this basis, a "volume expansion" and "polarity" rod-shaped or capsule-shaped solid is constructed, and it is compounded with a certain amount of Triton X-100 aqueous solution for mixed use, which can significantly improve the remediation effect of organochlorine pesticide-contaminated soil; at the same time, an alternating variable magnetic field is applied by using related electromagnetic rods, and the organochlorine pesticide pollution in the soil is adsorbed by the alternating variable magnetic field in coordination with the rod-shaped or capsule-shaped solid, which can greatly shorten the remediation time of organochlorine pesticide-contaminated soil, thereby providing a new remediation treatment method for the 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 of Examples 1-3 of the present invention and the control.

[0051] Figure 7 It is a histogram of pollutant removal rates of Examples 4-5 of the present invention and the control.

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

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

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

[0055] Embodiment 1:

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

[0057] Step 1, plowing the soil to be treated to a depth of 40 cm, while plowing, sprinkling the soil with a volume-enhancing polar-composite eluent, the mass ratio of the volume-enhancing polar-composite eluent sprinkling amount to the soil to be treated being 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, and each electromagnetic rod is connected to a control box;

[0060] It is understandable that the electromagnetic rod uses 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, but in theory the insertion depth is 10 cm deeper than the tillage 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, by alternately turning on each electromagnetic rod to construct an alternating variable magnetic field in the soil, taking each square meter of soil as a reference point, ensuring that the electromagnetic rods at adjacent reference points are alternately turned on, the alternating opening time is 15 minutes, each electromagnetic rod is turned on for 5 hours a day, and the magnetic field strength generated by a single electromagnetic rod is 13000G, and the removal of organochlorine pesticides in the soil is enhanced with a capacity-enhancing polar-composite eluent;

[0062] Step 4: Determine the content of organochlorine pesticides in the soil. When the soil meets the soil remediation standard, stir the electromagnetic rod while tilling to absorb the solids in the volume-enhancing polar-composite eluent;

[0063] The volume-increasing polar-composite eluent is obtained by mixing a solid and a Triton X-100 aqueous solution in a mass ratio of 1:4; wherein the solid 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 ​​capsule-shaped activated carbon fiber, and the surfactant is sodium dodecylbenzene sulfonate;

[0064] The preparation method of the solid material is:

[0065] S1. Preparation of expansion liquid: mixing the surfactant and water in a mass ratio of 3:20 to obtain an expansion 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 part of the substrate is clamped into the clamping hole of the carrier, and the two sides of the carrier are marked with side A and side B, and then the substrate on the A side of the carrier is immersed in a nitric acid solution for 2 minutes, the mass concentration of the nitric acid solution is 30%, 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 is manipulated so that the substrate on the A side is immersed in the expansion liquid and stirred for 15 seconds, then taken out from the expansion liquid and irradiated with an infrared lamp for 4 seconds, and the immersion-removal is repeated 10 times to complete the attachment of the surfactant at one end of the substrate;

[0070] S402, B side attachment: same Figure 5 As shown, the carrier plate is manipulated to immerse the substrate on the B side in the polar liquid, and 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, and the mixture is stirred for 15 seconds. Then, the substrate is taken out of the polar liquid and irradiated with an infrared lamp for 4 seconds, and the immersion-removal is repeated 10 times to complete the attachment of the magnetic material at one end of the substrate.

[0071] It can be understood 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 is different from Example 1 in that the mass ratio of the amount of the expanded polar-composite eluent to be sprayed to the soil to be treated is 2:1.

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

[0075] The above method is now used in a soil OCPs removal test using 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±65.5mg / kg, 150.03±55.4mg / kg, and 117.38±63.3mg / kg, respectively.

[0076] The plots were divided into two square meters each, the tillage depth was 40 cm, and the three indicators of o,p'-DDT, α-HCH, and o-nitrochlorobenzene were regulated as much as possible in each plot to keep them at (125.40 mg / kg, 150.03 mg / kg, and 117.38 mg / kg) in sequence. 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] Subsequently, the test soil was extracted with a 1:1 volume ratio of n-hexane / acetone on an accelerated solvent extractor (ASE-200, Dionex, USA) at a temperature of 100°C and a pressure of 1500 psi for 5 minutes. After three consecutive 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 purified with a n-hexane / acetone (volume ratio 98:2) purification solution in a solid phase extraction column (1g anhydrous sodium sulfate + 1.5g Florisil + 1.5g chromatography silica gel + 1g anhydrous sodium sulfate), the purified solution was collected and concentrated, and the volume was adjusted to 1 mL with n-hexane for GC analysis. The results are shown in Table 1 below:

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

[0079]

[0080] The control was treated with only a Triton X-100 aqueous solution without adding solids, and the other parameters were the same as those in Example 1. Figure 6 As shown, according to the bar chart, 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 is 98.23%; the pollutant removal rate of Example 2 is 96.42%; the pollutant removal rate of Example 3 is 98.52%; and the pollutant removal rate of the control is 79.40%;

[0082] It can be seen that the use of the expanded polar-composite eluent for soil pollutant removal has a more significant effect. By adding solids and alternating variable magnetic fields, the "increased" and "polar" rod-shaped or capsule-shaped solids can be constructed to efficiently adsorb soil pollutants under the action of the alternating variable magnetic field, and the adsorption effect can be enhanced by the synergy between surfactants and activated carbon fibers.

[0083] At the same time, by observing the histogram, it can be roughly seen that the pollutant removal rates of Example 3 and Example 1 are roughly the same, 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] Embodiment 4: This embodiment differs from Embodiment 1 in that the electromagnetic rods are inserted according to the soil area, such as 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] Embodiment 5: This embodiment differs from Embodiment 1 in that the electromagnetic rods are inserted according to the soil area, such as 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 above-mentioned electromagnetic rods. The results are as follows: Figure 7 As shown:

[0088] At the same time, a control is set up. Based on Example 1, two electromagnetic rods are respectively arranged at the geometrical adjacent corners of the area, and the arrangement positions of the electromagnetic rods inserted in each square meter of soil are the same, such as Figure 7 As shown, according to the bar chart, 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 arrangements, it can be found that the pollutant removal rate has decreased significantly. This may be due to the relatively weak magnetic effect of the alternating variable magnetic field distribution on the solids in the volume-enhancing polarity-composite eluent using the control, 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 increases, and it can be selected according to actual treatment requirements.

[0091] The following embodiments are 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, with each square meter of soil as the reference point, ensuring that the electromagnetic rods at adjacent reference points are turned on alternately, the alternating turning-on time is 10 minutes, each electromagnetic rod is turned on for 4 hours a day, and 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, with each square meter of soil as the reference point, ensuring that the electromagnetic rods at adjacent reference points are turned on alternately, the alternating turning-on time is 20 minutes, each electromagnetic rod is turned on for 6 hours a day, and the magnetic field strength generated by a single electromagnetic rod is 15000G.

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

[0095] At the same time, a control was set up, with Example 1 as the benchmark, and no alternating variable magnetic field was applied, such as Figure 8 As shown, according to the bar chart, 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 is 95.62%; the pollutant removal rate of Example 7 is 97.79%; the pollutant removal rate of the control is 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 in the volume-enhancing polarity-composite eluent lose the effect of the alternating variable magnetic field, making it impossible for them to deflect or shift. 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 shift too much, causing the distribution of solids in the soil to become irreversibly uneven, thereby destroying the uniform distribution of the solids and affecting the repair treatment effect of the solids to a certain extent.

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

[0099] Example 8: This example is different from Example 1 in that the volume-increasing polar-composite eluent is obtained by mixing solid matter and 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 volume-increasing polar-composite eluent is obtained by mixing solid matter and Triton X-100 aqueous solution in a mass ratio of 1:5.

[0101] Example 10: This example is different 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 is different from Example 1 in that the surfactant and water are mixed in a mass ratio of 2:10 to obtain a compatibilizer.

[0103] Example 12: This example is different from Example 1 in that chitosan is dissolved in 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 is different from Example 1 in that chitosan is dissolved in 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 is different from Example 1 in that, for the attachment on the A side, the carrier plate is manipulated so that the substrate on the A side is immersed in the expansion liquid and stirred for 10 seconds, then taken out of the expansion liquid and irradiated with an infrared lamp for 3 seconds, and the immersion-removal process is repeated 8 times to complete the attachment of the surfactant on one end of the substrate.

[0106] Example 15: This example is different from Example 1 in that, for the attachment on the A side, the carrier plate is manipulated so that the substrate on the A side is immersed in the expansion liquid and stirred for 20 seconds, then taken out of the expansion 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: This example is different from Example 1 in that, for the attachment on the B side, the carrier plate is manipulated to immerse the substrate on the B side in the polar liquid. 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. The mixture is stirred for 10 seconds, then taken out of the polar liquid and irradiated with an infrared lamp for 3 seconds. The immersion and removal is repeated 8 times to complete the attachment of the magnetic material to one end of the substrate.

[0108] Example 17: This example is different from Example 1 in that, for the attachment on the B side, the carrier plate is manipulated to immerse the substrate on the B side in the polar liquid. 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. Stirring is continued for 20 seconds. The substrate is then taken out of the polar liquid and irradiated with an infrared lamp for 5 seconds. The immersion and removal is repeated 12 times to complete the attachment of the magnetic material to one end of the substrate.

[0109] Example 18: This example is different 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 is different 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 are as follows: Fig. 9 As shown:

[0112] At the same time, a control was set up, with Example 1 as the benchmark, and no alternating variable magnetic field was applied, such as Fig. 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 under different ratios of the polar-composite eluent, the effect of its use is different. As the proportion of solids increases, the effect of the polar-composite eluent is better, but as the proportion of solids increases, the improvement effect gradually slows down. Therefore, the ratio can be selected according to the cost of use.

[0115] At the same time, by comparing different ratios of the expansion liquid and the polar liquid, it can be seen that as the dosage continues to increase, the prepared expansion polar-composite eluent has little effect. Considering from multiple angles such as removal effect and cost, the expansion liquid and polar liquid in Example 1 are relatively balanced;

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

[0117] By comparing the proportions of different Triton X-100, 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 in soil based on surface volume expansion and elution, characterized in that: The following steps are involved: Step 1, tilling the soil to be treated, while sprinkling the volume-increasing polar-composite eluent into the soil, so that the volume-increasing polar-composite eluent moistens the soil and the solids in the volume-increasing 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 capacitated 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, stir the electromagnetic rod while tilling to absorb the solids in the polar-composite eluent.

2. A method for removing OCPs in soil based on surface volume expansion and elution as claimed in claim 1, characterized in that: The volume-increasing 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 ​​rod-shaped activated carbon fiber or capsule-shaped activated carbon fiber.

3. A method for removing OCPs in soil based on surface volume expansion and elution as claimed in claim 2, characterized in that: The preparation method of the solid material is: S1. Preparation of expansion liquid: mixing the surfactant and water in a mass ratio of 1 to 2:10 to obtain an expansion 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 part of the substrate is clamped into the clamping hole of the carrier, and the two sides of the carrier are marked with side A and side B, and then the substrate on the side A of the carrier is immersed in a nitric acid solution for 1 to 2 minutes, and then rinsed with deionized water and dried in the shade; S4. Preparation of solid matter: S401, A side attachment: manipulate the carrier plate so that the substrate on the A side is immersed in the expansion liquid and stirred for 10 to 20 seconds, then taken out from the expansion liquid and irradiated with an infrared lamp for 3 to 5 seconds, and the immersion-removal is repeated 8 to 12 times to complete the attachment of the surfactant on 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, and at the same time, ferroferric oxide powder is added to the polar liquid according to the mass ratio of ferroferric oxide to chitosan of 1 to 2:1, and stirred continuously for 10 to 20 seconds, then taken out from the polar liquid and irradiated with an infrared lamp for 3 to 5 seconds, and the immersion-removal is repeated 8 to 12 times to complete the attachment of the magnetic material on one end of the substrate.

4. A method for removing OCPs in soil based on surface volume expansion and elution as claimed in claim 3, 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.

5. A method for removing OCPs in soil based on surface volume expansion and elution as claimed in claim 2, characterized in that: The content of Triton X-100 in the Triton X-100 aqueous solution is 80 to 120 g / L.

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

1.

7. A method for removing OCPs in soil based on surface volume expansion and elution as claimed in claim 1, characterized in that: 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.

8. A method for removing OCPs in soil based on surface volume expansion and elution as claimed in 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 arranged 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; 3) When 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.

9. A method for removing OCPs in soil based on surface volume expansion and elution as claimed in claim 1, characterized in that: 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.

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