A kind of curing agent for soil in-situ curing treatment and preparation method thereof

Abstract

The invention discloses a curing agent for in-situ curing treatment of soil and a preparation method thereof, wherein the curing agent for in-situ curing treatment of soil comprises 5-20 parts of pyrrole monomer, 10-50 parts of surfactant, 20-50 parts of initiator, 15-45 parts of cellulose ether and 30-105 parts of inorganic powder. The curing agent for in-situ curing treatment of soil prepared with pyrrole monomer, surfactant, initiator, cellulose ether and inorganic powder as raw materials can improve the bearing capacity and stability of soil and reduce the content of heavy metals in soil; and the raw materials used are simple and easy to obtain, the preparation method is simple, and the raw materials and production costs of the curing agent for in-situ curing treatment of soil can be reduced.

Description

Technical Field

[0001] The present invention relates to the field of soil remediation, and in particular to a curing agent for in-situ soil curing treatment and a preparation method thereof. Background Art

[0002] Soil has recycling capacity and is an important resource for people to survive. Under natural conditions, heavy metals in soil mainly come from parent rocks and residual biological materials. Generally, the content is relatively low and will not cause harm to the human body and the ecosystem. Human action is an important reason for soil pollution by heavy metals. In the process of metal ore development, urbanization, solid waste accumulation, and the application of fertilizers, pesticides, sludge and sewage irrigation to improve agricultural production, heavy metals can accumulate in the soil in large quantities. Heavy metals accumulated in the soil can enter the water body through leaching, or enter crops through agricultural activities such as planting, thereby causing harm to the human body and the ecosystem. The rapid economic development has caused a large area of ​​soil to have problems such as high water content and heavy metal pollution. The soil quality is worrying. It is imperative to artificially intervene in the soil to achieve the effect of soil solidification and repair.

[0003] At present, the traditional extensive remediation methods for soil in contaminated sites at home and abroad (stacking, landfilling, greening, horizontal barriers, etc.) are very likely to cause secondary environmental pollution and potential waste of resources, pose a high ecological safety risk, and have been gradually abandoned. Summary of the invention

[0004] One of the purposes of the present invention is to provide a soil in-situ curing agent to solve the above technical problems. The use of the in-situ curing agent is simple, economical, short-term and effective, and is widely used in soil curing and repair.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is: a curing agent for in-situ curing treatment of soil, comprising: pyrrole monomer, surfactant, initiator, cellulose ether and inorganic powder.

[0006] Furthermore, by weight, the pyrrole monomer is 5-20 parts; the surfactant is 10-50 parts; the initiator is 20-50 parts; the cellulose ether is 15-45 parts; and the inorganic powder is 30-105 parts. Illustratively, the pyrrole monomer is in the range of 5 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts or any two thereof; the surfactant is in the range of 10 parts, 20 parts, 30 parts, 40 parts, 50 parts or any two thereof; the initiator is in the range of 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts or any two thereof; the cellulose ether is in the range of 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts or any two thereof; the inorganic powder is in the range of 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, 105 parts or any two thereof.

[0007] Furthermore, the pyrrole monomer is 6-16 parts; the surfactant is 14-48 parts; the initiator is 20-45 parts; the cellulose ether is 16-40 parts; and the inorganic powder is 40-100 parts.

[0008] Furthermore, the molar ratio of the pyrrole monomer to the surfactant is 1:(0.3-0.8).

[0009] Furthermore, the molar ratio of pyrrole monomer to surfactant is 1:(0.4-0.6). Pyrrole monomer is polypyrrole, which is a colorless oily liquid at room temperature. It is a C, N five-membered heterocyclic molecule with a boiling point of 129.8°C and a density of 0.97g / cm 3 , slightly soluble in water.

[0010] Furthermore, the surfactant is a C4-C20 alkyl sulfonate.

[0011] Further, the surfactant is a C11-C20 alkyl sulfonate, and the C11-C20 alkyl sulfonate is selected from one or more of sodium undecylbenzene sulfonate, sodium undecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, sodium tridecylbenzene sulfonate, sodium tridecyl sulfonate, sodium tetradecyl sulfonate, sodium pentadecyl sulfonate, sodium hexadecylbenzene sulfonate, sodium hexadecyl sulfonate, sodium octadecylbenzene sulfonate, and sodium octadecyl sulfonate.

[0012] Furthermore, the C11-C20 alkyl sulfonate is C11-C20 alkylbenzene sulfonate, and the C11-C20 alkylbenzene sulfonate is selected from one or more of sodium dodecylbenzene sulfonate, sodium tridecylbenzene sulfonate, sodium hexadecylbenzene sulfonate, and sodium octadecylbenzene sulfonate.

[0013] Furthermore, the initiator is at least one of ammonium persulfate and ferric chloride.

[0014] Furthermore, the cellulose ether is at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose.

[0015] Furthermore, the inorganic powder is selected from one or more of kaolin, calcite, diatomaceous earth, expanded perlite, and red jade.

[0016] Furthermore, the inorganic powder is a mixture of kaolin and calcite.

[0017] Furthermore, the mass ratio of kaolin to calcite is 1:(1-5).

[0018] Furthermore, the mass ratio of kaolin to calcite is 1:(2-4).

[0019] Another object of the present invention is to provide a method for preparing the soil in-situ solidification treatment solidifying agent as described above, comprising the following steps:

[0020] S1, adding pyrrole monomer and cellulose ether to 200-2000 parts of water in sequence, stirring for 1-3 hours, to obtain a polymerization precursor solution;

[0021] S2, add a surfactant to the polymerization precursor solution, stir for 0.5-2h, then add an inorganic powder, stir and disperse for 0.5-2h to obtain a suspension;

[0022] S3. Add an aqueous solution containing an initiator to the suspension, continue stirring for 2-6 hours, and obtain an organic-inorganic composite powder containing modified polypyrrole, i.e., a curing agent for in-situ soil curing treatment, through centrifugation, washing, and drying.

[0023] Or include the following steps:

[0024] S1, adding pyrrole monomer and cellulose ether to 200-2000 parts of water in sequence, stirring for 1-3 hours, to obtain a polymerization precursor solution;

[0025] S2, adding a surfactant to the polymerization precursor solution, stirring for 0.5-2h to obtain a mixed solution;

[0026] S3, adding an aqueous solution containing an initiator to the mixed solution, stirring for 2-6 hours, centrifuging, washing, and drying to obtain an organic modifier;

[0027] S4. Mix the organic modifier and the inorganic powder and grind them for 0.5-2h to obtain a curing agent for in-situ soil curing treatment.

[0028] The beneficial effects of the present invention are:

[0029] 1) In response to the current problems of high water content and heavy metal pollution in the soil, an organic-inorganic composite powder (solidifying agent for in-situ soil solidification treatment) was prepared using pyrrole monomer, surfactant, initiator, cellulose ether and inorganic powder as raw materials. It can improve the bearing capacity and stability of the soil and reduce the heavy metal content in the soil. The raw materials used are simple and easy to obtain, and the preparation method is simple, which can reduce the raw material and production costs of the soil in-situ solidification treatment solidifying agent.

[0030] 2) The present invention uses cellulose ether containing a large number of active groups as a growth template for polypyrrole to construct overlapping transport channels. The surface of cellulose ether contains a large number of hydroxyl groups, which can not only establish a connection relationship with pyrrole through hydrogen bonds to induce it to aggregate into overlapping transport channels; but also can cooperate with surfactants to destroy the water film on the surface of soil particles, so that water molecules are dispersed and absorbed in the transport channels, effectively optimizing the soil water content and improving the aggregation of soil particles.

[0031] 3) Introducing surfactants on the surface of polypyrrole, polypyrrole acts as a hydrophilic end and adsorbs on the surface of soil particles to destroy the water film on the surface of soil particles. The alkyl chain in the surfactant can improve the hydrophobicity and, as a hydrophobic end, play a waterproof and anti-seepage role, balance the soil moisture and prevent water penetration. Therefore, the introduction of surfactants into polypyrrole gives polypyrrole amphiphilicity, which can destroy the water film on the surface of soil particles, increase the aggregation of soil particles, and thus improve the soil bearing capacity and stability.

[0032] 4) The introduction of inorganic powder can not only effectively fix heavy metal ions, but also has a certain viscosity, thereby improving soil density and interfacial adhesion, synergistically modifying polypyrrole, and jointly optimizing soil bearing capacity and soil stability.

[0033] 5) Modified polypyrrole has a functional closed loop of destroying the water film on the surface of soil particles and absorbing excess water, thereby regulating the internal structure of the soil and improving the soil bearing capacity. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0035] Except as shown in the operating examples or otherwise indicated, all numbers used in the specification and claims to indicate the amount of ingredients, physicochemical properties, etc. are understood to be adjusted by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters listed in the above specification and the attached claims are approximate values, and those skilled in the art can use the teachings disclosed herein to seek to obtain the desired properties and appropriately change these approximate values. The use of numerical ranges expressed as endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0036] The applicant found that the rapid economic development has caused a large area of ​​soil to have high water content, heavy metal pollution and other problems, and the soil quality is worrying. It is imperative to carry out artificial intervention in the soil to achieve the effect of soil solidification and repair.

[0037] The embodiment of the present invention provides a curing agent for in-situ curing treatment of soil to solve the above problems, which specifically includes the following steps:

[0038] S1. Add pyrrole monomer and cellulose ether into 200-2000 parts of water in sequence, and stir for 1-3 hours to obtain a polymerization precursor solution.

[0039] In some embodiments, the pyrrole monomer is present in an amount of 5-20 parts.

[0040] In some embodiments, the pyrrole monomer is present in an amount of 6-16 parts.

[0041] In some embodiments, the cellulose ether is 16-40 parts.

[0042] In some embodiments, the cellulose ether is 15-45 parts; the cellulose ether is at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose.

[0043] S2. Add 10-50 parts of surfactant to the polymerization precursor solution, stir for 0.5-2 hours, then add 30-105 parts of inorganic powder, stir and disperse for 0.5-2 hours to obtain a suspension, wherein the molar ratio of pyrrole monomer to surfactant is 1: (0.3-0.8), preferably 1: (0.4-0.6).

[0044] In some embodiments, the surfactant is preferably 14-48 parts, and the surfactant is a C4-C20 alkyl sulfonate, and more preferably a C11-C20 alkyl sulfonate.

[0045] In some embodiments, the C11-C20 alkyl sulfonate is at least one of sodium undecylbenzene sulfonate, sodium undecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, sodium tridecylbenzene sulfonate, sodium tridecyl sulfonate, sodium tetradecyl sulfonate, sodium pentadecyl sulfonate, sodium hexadecylbenzene sulfonate, sodium hexadecyl sulfonate, sodium octadecylbenzene sulfonate, and sodium octadecyl sulfonate.

[0046] In some embodiments, the C11-C20 alkyl sulfonate is C11-C20 alkyl benzene sulfonate.

[0047] In some embodiments, the C11-C20 alkylbenzene sulfonate is at least one of sodium dodecylbenzene sulfonate, sodium tridecylbenzene sulfonate, sodium hexadecylbenzene sulfonate, and sodium octadecylbenzene sulfonate.

[0048] In some embodiments, the inorganic powder is preferably 40-100 parts, and the inorganic powder is at least one of kaolin, calcite, diatomaceous earth, expanded perlite, and red jade.

[0049] In some embodiments, the inorganic powder is a mixture of kaolin and calcite, and the mass ratio of kaolin to calcite is 1:(1-5). More preferably, the mass ratio of kaolin to calcite is 1:(2-4).

[0050] S3. Add 20-50 parts of initiator and 30-200 parts of water to prepare an initiator aqueous solution, add the initiator aqueous solution to the suspension, continue stirring for 2-6 hours, centrifuge, wash and dry to obtain a curing agent for in-situ curing treatment of soil containing modified polypyrrole.

[0051] In some embodiments, the initiator is preferably 20-45 parts, and the initiator is at least one of ammonium persulfate and ferric chloride.

[0052] In addition, the following method can be used to prepare the curing agent for in-situ soil curing treatment:

[0053] S1, adding pyrrole monomer and cellulose ether to 200-2000 parts of water in sequence, stirring for 1-3 hours, to obtain a polymerization precursor solution;

[0054] S2, adding a surfactant to the polymerization precursor solution, stirring for 0.5-2h to obtain a mixed solution;

[0055] S3, adding an aqueous solution containing an initiator to the mixed solution, stirring for 2-6 hours, centrifuging, washing, and drying to obtain an organic modifier;

[0056] S4. Mix the organic modifier and the inorganic powder and grind them for 0.5-2h to obtain a curing agent for in-situ soil curing treatment.

[0057] Example

[0058] The following examples describe the disclosure of the present invention in more detail, and these examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present invention will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0059] Example 1

[0060] A curing agent for in-situ soil curing treatment comprises the following components: 10.2 parts of pyrrole monomer (67.09 g / mol), 26 parts of cellulose ether (hydroxymethyl cellulose), 27 parts of surfactant (sodium dodecylbenzene sulfonate (348.48 g / mol)), 66 parts of inorganic powder (17 parts of kaolin and 49 parts of calcite), and 30 parts of initiator (ammonium persulfate).

[0061] The molar ratio of pyrrole monomer to surfactant is (10.2 / 67.09):(27 / 348.48)=1:0.51. The weight ratio of kaolin to calcite is 17:49=1:2.88.

[0062] A method for preparing a curing agent for in-situ soil curing treatment, specifically comprising the following steps:

[0063] S1. Add pyrrole monomer and hydroxymethyl cellulose to 1000 parts of water in sequence and stir for 2 hours to obtain a polymerization precursor solution.

[0064] S2. Add sodium dodecylbenzene sulfonate to the polymerization precursor solution, stir for 1 hour, then add kaolin and calcite, stir and disperse for 1 hour to obtain a suspension.

[0065] S3. Add 45 parts of water to ammonium persulfate to prepare an initiator aqueous solution, add the initiator aqueous solution to the suspension, continue stirring for 4 hours, centrifuge, wash and dry to obtain a curing agent for in-situ curing treatment of soil containing modified polypyrrole.

[0066] Example 2

[0067] A curing agent for in-situ soil curing treatment comprises the following components: 6.5 parts of pyrrole monomer (67.09 g / mol), 16 parts of cellulose ether (hydroxyethyl cellulose), 14 parts of surfactant (sodium dodecylbenzene sulfonate (348.48 g / mol)), 42 parts of inorganic powder (14 parts of kaolin and 28 parts of calcite), and 20 parts of initiator (ammonium persulfate).

[0068] The molar ratio of pyrrole monomer to surfactant is: (6.5 / 67.09):(14 / 348.48)=0.41

[0069] The weight ratio of kaolin and calcite is: 14:28=1:2.

[0070] A method for preparing a curing agent for in-situ soil curing treatment, specifically comprising the following steps:

[0071] S1. Add pyrrole monomer and hydroxyethyl cellulose into 800 parts of water in sequence and stir for 2 hours to obtain a polymerization precursor solution.

[0072] S2. Add sodium dodecylbenzene sulfonate to the polymerization precursor solution, stir for 1 hour, then add kaolin and calcite, stir and disperse for 1 hour to obtain a suspension.

[0073] S3. Add 30 parts of water to ammonium persulfate to prepare an initiator aqueous solution, add the initiator aqueous solution to the suspension, continue stirring for 4 hours, centrifuge, wash, and dry to obtain a curing agent for in-situ curing treatment of soil containing modified polypyrrole.

[0074] Example 3

[0075] A curing agent for in-situ soil curing treatment comprises the following components: 16 parts of pyrrole monomer (67.09 g / mol), 40 parts of cellulose ether (hydroxypropyl methylcellulose), 48 parts of surfactant (sodium dodecylbenzene sulfonate (348.48 g / mol)), 100 parts of inorganic powder (20 parts of kaolin and 80 parts of calcite), and 45 parts of initiator (ammonium persulfate).

[0076] The molar ratio of pyrrole monomer to surfactant is: (16 / 67.09):(48 / 348.48)=0.58.

[0077] The weight ratio of kaolin and calcite is: 20:80=1:4.

[0078] A method for preparing a curing agent for in-situ soil curing treatment, specifically comprising the following steps:

[0079] S1. Add pyrrole monomer and hydroxypropyl methylcellulose to 1500 parts of water in sequence and stir for 2 hours to obtain a polymerization precursor solution.

[0080] S2. Add sodium dodecylbenzene sulfonate to the polymerization precursor solution, stir for 1 hour, then add kaolin and calcite, stir and disperse for 1 hour to obtain a suspension.

[0081] S3. Add 70 parts of water to ammonium persulfate to prepare an initiator aqueous solution, add the initiator aqueous solution to the suspension, continue stirring for 4 hours, centrifuge, wash and dry to obtain a curing agent for in-situ curing treatment of soil containing modified polypyrrole.

[0082] Example 4

[0083] Example 4 is basically the same as Example 1, the main difference being that the inorganic powder used contains 33 parts of kaolin and 33 parts of calcite, and the weight ratio of kaolin to calcite is 33:33=1:1.

[0084] Example 5

[0085] Example 5 is basically the same as Example 1, the main difference being that the inorganic powder used contains 11 parts of kaolin and 55 parts of calcite, and the weight ratio of kaolin to calcite is 11:55=1:5.

[0086] Example 6

[0087] Example 6 is substantially the same as Example 1, the main difference being that the surfactant used is sodium octylbenzenesulfonate.

[0088] Example 7

[0089] Example 7 is substantially the same as Example 1, the main difference being that the surfactant used is sodium octadecylbenzenesulfonate.

[0090] Example 8

[0091] Example 8 is substantially the same as Example 1, the main difference being that the surfactant used is sodium dodecyl sulfate.

[0092] Example 9

[0093] Example 9 is basically the same as Example 1, the main difference being that physical grinding is used instead of coating. The specific grinding steps include:

[0094] S1. Add pyrrole monomer and hydroxymethyl cellulose to 1000 parts of water in sequence and stir for 2 hours to obtain a polymerization precursor solution.

[0095] S2. Add sodium dodecylbenzene sulfonate to the polymerization precursor solution and stir for 1 hour to obtain a suspension.

[0096] S3, adding 45 parts of water to ammonium persulfate to prepare an initiator aqueous solution, adding the initiator aqueous solution to the suspension, stirring for 4 hours, centrifuging, washing, and drying to obtain an organic modifier;

[0097] S4. The organic modifier is mixed with inorganic powders (kaolin and calcite) and ball-milled for 1 hour to obtain a solidifying agent for in-situ soil solidification treatment.

[0098] Example 10

[0099] Example 10 is basically the same as Example 1, the main difference being that the amount of surfactant (sodium dodecylbenzene sulfonate) used is 16 parts, and the molar ratio of pyrrole monomer to surfactant is: (10.2 / 67.09):(16 / 348.48)=1:0.30.

[0100] Embodiment 11

[0101] Example 11 is basically the same as Example 1, the main difference being that the amount of surfactant (sodium dodecylbenzene sulfonate) used is 42 parts, and the molar ratio of pyrrole monomer to surfactant is: (10.2 / 67.09):(42 / 348.48)=1:0.79.

[0102] Comparative Example 1

[0103] Comparative Example 1 is substantially the same as Example 1, the main difference being that the inorganic powders used are all kaolin, without calcite.

[0104] Comparative Example 2

[0105] Comparative Example 2 is substantially the same as Example 1, the main difference being that the inorganic powders used are all calcite, without kaolin.

[0106] Comparative Example 3

[0107] Comparative Example 3 is substantially the same as Example 1, the main difference being that methyl cellulose is used instead of hydroxymethyl cellulose.

[0108] Comparative Example 4

[0109] Comparative Example 4 is substantially the same as Example 1, except that the cellulose ether is not contained. S1 is as follows: pyrrole monomer is added to 1000 parts of water and stirred for 2 hours to obtain a polymerization precursor solution.

[0110] Comparative Example 5

[0111] Comparative Example 5 is substantially the same as Example 1, the main difference being that in step S2, no inorganic powder is added.

[0112] Experimental Examples

[0113] Take the air-dried heavy metal ion Cu 2+ 、Cd 2+ 150 g of contaminated soil sample was added with the soil in-situ curing agent prepared in Example 1-11 and Comparative Example 1-5 at 5% of the weight of the soil, mixed evenly, and then water was added to make the soil moisture content 20%. After sufficient stirring, a cylindrical sample of Φ150 mm×H150 mm was made, demoulded, and after curing for 7 days, the unconfined compressive strength (bearing capacity) and heavy metal content in the soil were tested. The test results are shown in Table 1.

[0114] The unconfined compressive strength is tested in accordance with T0805-1994 "Test method for unconfined compressive strength of materials stabilized with inorganic binders".

[0115] Heavy metal content detection: The soil after curing is crushed and toxic leaching (heavy metal leaching test) is carried out according to HJ T299-2007 "Toxicity leaching method of solid waste leaching - sulfuric acid and nitric acid method".

[0116] Table 1: Soil carrying capacity and heavy metal content

[0117]

[0118] From the data detected in Examples 1 to 5 and Comparative Examples 1, 2, and 5, it can be seen that the soil in-situ solidification treatment curing agent prepared in Examples 1 to 3 can well enhance the bearing capacity of the soil and reduce the heavy metal Cu in the soil. 2+ 、Cd 2+ The content.

[0119] In Example 4, the fixation effect on heavy metal ions is reduced. This may be because the weight ratio of kaolin and calcite in Example 4 is 1:1. There is too much kaolin, and the effect of kaolin on heavy metal ions is more of adsorption and fixation, while calcite can generate insoluble heavy metal salts through precipitation reaction with heavy metal ions, thereby better reducing the biological effectiveness and mobility of heavy metal ions, resulting in a decrease in the overall stabilizing effect of inorganic powder on heavy metal ions in soil. However, kaolin has viscosity after absorbing water, which can appropriately compensate for the filling effect of insoluble heavy metal salts, and therefore has basically no adverse effect on the bearing capacity.

[0120] In Example 5, the bearing capacity decreased and the heavy metal content decreased slightly. This may be because the weight ratio of kaolin and calcite in this example is 1:5. There is too little kaolin, and the bonding strength of the organic-inorganic interface decreases, so the soil bearing capacity decreases. More calcite is conducive to the formation of insoluble heavy metal salts, which has a better stabilizing effect on heavy metal ions.

[0121] In comparative example 1, the carrying capacity decreased slightly, and the heavy metal ion fixation effect decreased significantly. This may be because the inorganic powder only contained kaolinite and no calcite. Kaolinite mainly fixes metal ions by adsorption and cannot promote the formation of insoluble metal salts. Its effect is not as good as calcite. 2+ 、Cd 2+ The content of Cu in Example 1 2+ 、Cd 2+ The content is high and there is a lack of in-situ generated insoluble metal salts to fill the pores, so the bearing capacity is also affected.

[0122] The bearing capacity in Comparative Example 2 decreased significantly. The possible reason is that the inorganic powder is only calcite. Although it has a better fixation effect on heavy metal ions, it is difficult to contribute bonding strength to the soil system, thereby reducing the stability and bearing capacity of the soil.

[0123] In Comparative Example 5, the bearing capacity and heavy metal ion fixation effect are significantly reduced. The possible reason is that without adding inorganic powder, the fixation effect of organic-inorganic composite powder on heavy metals in the soil is significantly reduced, and the pores in the soil cannot be effectively filled, thereby affecting the internal structure of the soil, and it is unable to further provide bonding, thereby reducing the density and bearing capacity of the soil.

[0124] Therefore, inorganic powder is added to the curing agent for in-situ soil curing treatment. The inorganic powder will produce a certain viscosity in the soil system, improve the adhesion between the organic-inorganic composite powder and the soil, and the precipitate generated by the complexing heavy metal ions can effectively fill the soil pores, thereby improving the soil density, optimizing the soil bearing capacity, and improving the soil stability. When a mixture of kaolin and calcite is added in proportion, the effect is better than adding kaolin or calcite alone, with an effect of 1+1>2, and the weight ratio of kaolin and calcite is controlled at 1: (2-4) for the best effect.

[0125] In Example 1 and Examples 6 to 8, compared with Example 1, the bearing capacity and heavy metal ion fixation effect in Example 6 are both reduced. This may be because sodium octylbenzene sulfonate (C8) is used in Example 6, the alkyl chain is relatively short, the hydrophobic effect is weak, and the soil particles contacting water will increase the repulsion between the soil, and then the cohesion between the soil particles will decrease. Therefore, the soil bearing capacity decreases, the cohesion of the soil particles decreases, and the overall structure is relatively loose, which makes the heavy metal ions adsorbed by kaolin easy to be freed in the heavy metal leaching test, thereby reducing the heavy metal ion fixation effect.

[0126] The soil bearing capacity in Example 7 is higher, mainly because sodium octadecylbenzene sulfonate has a relatively longer alkyl chain and better hydrophobicity, which is beneficial to the optimization of the internal structure of the soil, thereby improving the soil bearing capacity.

[0127] In Example 8, sodium dodecyl sulfate is used, which does not contain a benzene ring in its structure, and the rigidity and steric hindrance are reduced, which may lead to uneven grafting of the surfactant on the polypyrrole, and the existence of local accumulation and entanglement, thereby affecting the effectiveness of the curing agent for in-situ soil curing treatment, and ultimately leading to a decrease in soil bearing capacity. Therefore, the surfactant is preferably a C11-C20 alkylbenzene sulfonate.

[0128] From the test data of Example 1 and Example 9, it can be seen that the bearing capacity of Example 9 is reduced. This may be because physical grinding is used instead of coating in Example 9. Compared with the coating method, the physical grinding method makes the interface bonding force between the inorganic powder and the organic matter relatively weak, so the bearing capacity of the soil is reduced.

[0129] From the test data of Example 1 and Examples 10-11, it can be seen that the carrying capacity in Example 10 is significantly reduced, and the heavy metal fixation effect is also reduced. This may be because the molar ratio of pyrrole monomer to surfactant in Example 10 is 1:0.30, the content of surfactant is relatively small, and the hydrophobic effect is relatively poor, which makes it easy for soil particles to contact water, resulting in an increase in the repulsive force between soil particles and a decrease in cohesion. Therefore, the carrying capacity is reduced and the structure is loose, which in turn affects the fixation of heavy metal ions to a certain extent, especially the heavy metal ions fixed by adsorption.

[0130] The carrying capacity in Example 11 also decreased significantly. This may be because too much surfactant is not conducive to the hydrophilic effect of pyrrole, which worsens the destructive effect on the water film on the surface of soil particles, resulting in low cohesion of soil particles and low carrying capacity.

[0131] From the test data of Example 1, Comparative Example 3 and Comparative Example 4, it can be seen that the best effect is achieved by using cellulose ether containing hydroxyl groups. In Example 1, the surface of hydroxymethyl cellulose contains a large number of hydroxyl groups, which can not only establish a connection relationship with pyrrole through hydrogen bonds, inducing it to aggregate into overlapping transport channels; but also can cooperate with surfactants to destroy the water film on the surface of soil particles, so that water molecules are dispersed and absorbed in the transport channels, effectively optimizing the soil water content and improving the aggregation of soil particles.

[0132] In Comparative Example 3, the bearing capacity is significantly reduced. This may be due to the use of methyl cellulose, which does not contain hydroxyl groups and cannot support and guide the polypyrrole to form an overlapping structure. The distribution of pyrrole rings is chaotic, thereby weakening the regulatory effect of the organic-inorganic composite powder on the internal structure of the soil, reducing the soil bearing capacity, and also affecting the fixation effect of heavy metal ions to a certain extent.

[0133] In Comparative Example 4, the bearing capacity further decreased. This may be because Comparative Example 4 does not contain cellulose, and polypyrrole cannot construct a structure that overlaps each other, and reduces the effect of dispersing and absorbing water in the soil, and the internal structure of the soil deteriorates, so the bearing capacity is reduced and the heavy metal ion fixation effect is reduced.

[0134] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A soil in-situ curing agent, characterized in that: The invention comprises, by weight: 5-20 parts of pyrrole monomer, 10-50 parts of surfactant, 20-50 parts of initiator, 15-45 parts of cellulose ether and 30-105 parts of inorganic powder; The surfactant is a C11-C20 alkyl sulfonate; The inorganic powder is a mixture of kaolin and calcite; The initiator is at least one of ammonium persulfate and ferric chloride; The cellulose ether is at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose; The method for preparing the curing agent for in-situ soil curing treatment comprises the following steps: S1, adding pyrrole monomer and cellulose ether into water in sequence, stirring, to obtain a polymerization precursor solution; S2, adding a surfactant to the polymerization precursor solution, stirring; then adding an inorganic powder, stirring and dispersing, to obtain a suspension; S3, adding an initiator to the suspension, stirring, centrifuging, washing, and drying to obtain a curing agent; Or include the following steps: S1, adding pyrrole monomer and cellulose ether into water in sequence, stirring, to obtain a polymerization precursor solution; S2, adding a surfactant to the polymerization precursor solution, stirring, and obtaining a mixed solution; S3, adding an initiator to the mixed solution, stirring, centrifuging, washing, and drying to obtain an organic modifier; S4, mixing and grinding the organic modifier and the inorganic powder to obtain a curing agent.

2. The solidifying agent for in-situ soil solidification treatment according to claim 1, characterized in that: The molar ratio of the pyrrole monomer to the surfactant is 1:(0.3-0.8).

3. The solidifying agent for in-situ soil solidification treatment according to claim 1, characterized in that: The molar ratio of the pyrrole monomer to the surfactant is 1:(0.4-0.6).

4. The curing agent for in-situ soil curing treatment according to any one of claims 1 to 3, characterized in that: The C11-C20 alkyl sulfonate is selected from one or more of sodium undecylbenzene sulfonate, sodium undecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, sodium tridecylbenzene sulfonate, sodium tridecyl sulfonate, sodium tetradecyl sulfonate, sodium pentadecyl sulfonate, sodium hexadecylbenzene sulfonate, sodium hexadecyl sulfonate, sodium octadecylbenzene sulfonate and sodium octadecyl sulfonate.

5. The solidifying agent for in-situ soil solidification treatment according to claim 4, characterized in that: The C11-C20 alkyl sulfonate is C11-C20 alkylbenzene sulfonate, and the C11-C20 alkylbenzene sulfonate is selected from one or more of sodium dodecylbenzene sulfonate, sodium tridecylbenzene sulfonate, sodium hexadecylbenzene sulfonate, and sodium octadecylbenzene sulfonate.

6. The solidifying agent for in-situ soil solidification treatment according to claim 1, characterized in that: The mass ratio of the kaolin and calcite is 1:(1-5).

7. The solidifying agent for in-situ soil solidification treatment according to claim 1, characterized in that: The mass ratio of the kaolin and calcite is 1:(2-4).

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