Humic Acid Composite Remediation Material for Coal Chemical Pollution Sites and Its Preparation Method

Abstract

This invention belongs to the field of soil remediation materials, specifically relating to a humic acid composite remediation material for coal chemical contaminated sites and its preparation method. The method includes: 1) mixing raw materials, alkaline solution, and phosphide evenly, allowing the mixture to stand, collecting the supernatant, adding acid to adjust the pH value, and filtering to obtain a humic acid solution; 2) drying the solid obtained in step 1), adding acid and mixing evenly, filtering and washing, adding strong acid for corrosion, filtering and washing again, and drying to obtain a substrate; 3) heating organic raw materials, emulsifier, and solvent, while maintaining stirring, adding a mixture of acyclic carboxylic acid and humic acid solution, adding an initiator, and performing a thermal reaction. The hot substrate is then added and mixed evenly, and the mixture is dried and ground to obtain the humic acid composite remediation material. This humic acid composite remediation material can effectively improve soil structure and quality, and effectively enhance the efficiency of soil remediation.

Description

Technical Field

[0001] This invention belongs to the field of soil remediation materials, specifically relating to a humic acid composite remediation material for coal chemical contaminated sites and its preparation method. Background Technology

[0002] Soil problems at coal chemical contaminated sites mainly manifest as organic and heavy metal pollution. These pollutants typically originate from wastewater and solid waste generated during coal chemical production. Due to the complex composition and high concentration of toxic and hazardous substances in chemical emissions, these substances easily penetrate deep into the soil, causing widespread soil pollution. The long-term pollution of soil around chemical plants by wastewater and exhaust gases severely impacts the surrounding environment. The toxic substances in wastewater and exhaust gases from chemical production penetrate deep into the soil, extending the contamination to groundwater levels. The long-term accumulation of toxic substances from wastewater and exhaust gases results in a prolonged period of soil pollution residue. Currently, due to the combined effects of rural township enterprises, agricultural production, sewage irrigation, fertilizers and pesticides, and agricultural films, soil pollution leading to degradation of soil environmental quality and ecological functions has become one of the main threats to soil function degradation.

[0003] To address this issue and avoid impacting soil physicochemical properties, microbial communities, and enzyme activity, humic acid, a natural organic compound, is commonly used for soil remediation. Humic acid possesses diverse structures, numerous functional groups, large molecules, and wide distribution, exhibiting various physicochemical properties such as solubility, acidity, ion exchange capacity, and complexing (chelating) properties. It can efficiently adsorb polluted soils containing heavy metals, organic pollutants, and radioactive contaminants.

[0004] However, the classification and composition of existing humic acid materials are unclear. Commercially, they are divided into coal-based humic acid and biochemical humic acid. Coal chemical industry further classifies coal-based humic acid into fulvic acid, brown humic acid, and black humic acid, and also into water-soluble humic acid, insoluble humic acid, and macromolecular and small-molecule humic acid. However, industrial research on the basic modification of humic acid is insufficient, and some industries even directly use unactivated weathered coal and lignite for modification, resulting in insufficient soil remediation effects and even adverse effects. This fails to address specific problems such as humic acid-degraded soil improvement and the remediation of heavy metal and organic pollution. Summary of the Invention

[0005] Based on the above, in order to address the problems of high soil pollution levels, wide pollution range, deep pollution depth, and long pollution duration in coal chemical contaminated sites, this invention proposes a humic acid composite remediation material for coal chemical contaminated sites and its preparation method.

[0006] The purpose of this invention is:

[0007] First, it can effectively improve soil structure and quality;

[0008] Second, it can effectively improve the efficiency of soil remediation.

[0009] To achieve the above objectives, the present invention adopts the following technical solution.

[0010] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites.

[0011] The method includes:

[0012] 1) Take the raw materials, alkali solution and phosphide, mix them evenly, let them stand, take the supernatant, add acid solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0013] 2) Drying Step 1) The solid obtained from the static operation is mixed with acid solution, filtered and washed, then corroded with strong acid, filtered and washed again, and dried to obtain the substrate.

[0014] 3) Take organic raw materials, emulsifiers, and solvents, heat them, and while stirring, add a mixture of acyclic carboxylic acid and humic acid solution, add an initiator, and after a thermal reaction, add the hot substrate and mix evenly. After drying and grinding, obtain humic acid composite repair material.

[0015] As a preferred option

[0016] The raw material mentioned in step 1) is low-quality coal;

[0017] The low-quality coal is lignite and / or weathered coal and / or coal.

[0018] The alkaline solution is a 0.1–0.5 mol / L NaOH aqueous solution, and its dosage is 5.0–10.0 mL / g of raw material;

[0019] The phosphide is sodium pyrophosphate, and its dosage is 0.05-0.10 g / g raw material.

[0020] As a preferred option

[0021] The acid solution in step 1) is a 0.1-0.5 mol / L HCl aqueous solution, and the amount used is 1.0-1.5 mL / g of raw material.

[0022] As a preferred option

[0023] In step 2), the product is washed with distilled water until it becomes neutral.

[0024] The strong acid in step 2) is a 35-45 wt% HF aqueous solution, and the amount used is 5-10 mL / g of the solid obtained in step 1).

[0025] As a preferred option

[0026] The organic raw materials mentioned in step 3) are butyl acrylate and cyclohexane;

[0027] The mass ratio of butyl acrylate to cyclohexane is 1:(0.2-0.3);

[0028] The emulsifier is tristearate sorbitan, and its dosage is 0.01-0.05 g / g organic raw material;

[0029] The solvent is acetone, and its dosage is 15-25 mL / g organic raw material;

[0030] Step 3) describes the heating process, where the temperature is raised to 50-60°C.

[0031] As a preferred option

[0032] In step 3), the mixture of acyclic carboxylic acid and humic acid solutions:

[0033] The acyclic carboxylic acid is acrylic acid;

[0034] The acyclic carboxylic acid and humic acid solution were prepared and mixed evenly at a volume ratio of 1:(0.5-0.7).

[0035] As a preferred option

[0036] Step 3) The initiator is potassium persulfate, and its dosage is 0.05-0.1 g / g organic raw material;

[0037] The thermal reaction described in step 3) is carried out at 80-90°C for 2-5 hours.

[0038] As a preferred option

[0039] Step 3) The substrate is added at a rate of 0.9 to 1.1 g per gram of organic raw material.

[0040] As a preferred option

[0041] After grinding in step 3), the material is passed through a 60-100 mesh sieve.

[0042] A humic acid composite remediation material for coal chemical contaminated sites.

[0043] Soil contaminants in coal chemical contaminated sites include polycyclic aromatic hydrocarbons (benzo[a]pyrene, fluoranthene, pyrene, etc.), chlorinated hydrocarbons (1,2-dichloropropane, 1,2,3-trichloropropane, etc.), organic pollutants (chloroform, bis(2-chloroisopropyl) ether, etc.), and a large number of heavy metal pollutants. These pollutants have a serious negative impact on the soil, and the removal of heavy metal pollutants is particularly difficult and costly. To address the remediation of coal chemical contaminated sites, this invention provides a humic acid composite remediation material for such sites, as well as a method for preparing this material.

[0044] According to research by those skilled in the art, insoluble humic acid has a significant passivation and remediation effect on heavy metals in soil. The technical solution of this invention is based on the modification of insoluble humic acid, and the raw materials can be obtained from coal chemical plants, greatly reducing preparation costs. This invention first obtains humic acid (brown humic acid) and fulvic acid, rich in functional groups such as carbonyl, carboxyl, and etheroxy groups, through leaching with dilute alkaline solution and acid-assisted precipitation. The combined state of humic acid, which is sparingly soluble in water but readily soluble in water, is complexed into readily soluble humate salts. Combined with sodium pyrophosphate, this significantly increases the extraction yield of humic acid. Experiments have shown that using "NaOH solution dissolution and HCl solution precipitation" is more effective than "KOH solution dissolution and HNO3 solution precipitation." Considering that the cations of substances such as sodium pyrophosphate are sodium, this invention uses NaOH solution for alkaline dissolution. HNO3 solution has a strong oxidizing effect and can react with functional groups, degrading large humic acid molecules into smaller molecules. Furthermore, because the solution is rich in divalent metal ions, this invention avoids the use of sulfuric acid, otherwise precipitation will occur, reducing the purity of the humic acid product. However, if the pH value of acid precipitation is too high, it will cause other impurities to dissolve, affecting the purity of humic acid.

[0045] The active groups of humic acid can chelate with small molecules or complex with metal ions. Dissolved heavy metal ions in the soil undergo exchange reactions with humic acid, which can reduce the soil's basicity. Acidic functional groups release H+. +Humic acid neutralizes alkaline substances in the soil, reducing soil alkalinity. The aldehyde and carboxyl functional groups in humic acid react with cations in the soil to form humates, creating a buffer system for the interconversion of humic acid and humates. However, unmodified humic acid has a complex composition and insufficient complexing ability for metal ions, leading to the precipitation of large amounts of phosphorus with iron and aluminum in the soil, resulting in loss of activity. In alkaline soils, humic acid is not effective at chelating or complexing iron and aluminum. To enhance the complexing ability of humic acid for metal ions, this invention modifies it based on demineralized low-quality coal. After strong acid corrosion, the porosity of the substrate increases, the surface of the humic acid-based composite material becomes more complex and rough, the particle diameter increases, and more heterogeneous surfaces are presented, providing a large number of adsorption sites, making it easier for heavy metal ions to be adsorbed onto the composite material. This is because oxygen-containing functional groups such as hydroxyl, carboxyl, epoxy, carbonyl, and lactone are considered important surface functional groups for adsorbing heavy metal ions and can form organic complexes with them. After modification, the number of oxygen-containing functional groups on the surface of the humic acid-based composite material significantly increased, especially phenolic ether groups, carbon-carbon double bonds, and aromatic bonds, and the number of adsorption sites on the material surface also increased. Both carboxyl and hydroxyl functional groups on the material underwent coordination complexation reactions with Pb, Hg, and Cd heavy metal ions. Furthermore, Pb, Hg, and Cd ions rapidly occupied the adsorption sites provided by the humic acid-based composite material surface, resulting in extremely fast reaction rates and the adsorption of more metal ions to form metal complexes. Simultaneously, heavy metal ions underwent ion exchange with oxygen-containing functional groups to form insoluble metal complexes, thereby reducing the accumulation of heavy metals by soil organisms. Synergistically, the polymer's surface modification effect resulted in excellent solubilization of the humic acid composite remediation material. When the humic acid composite remediation material formed an organic-inorganic composite colloid with soil particles, the material's adsorption capacity for organic matter was enhanced, leading to a decrease in the content of organic pollutants in the soil.

[0046] Meanwhile, as the amount of humic acid solution increases, the adsorption driving force of the material is enhanced, and effective groups are attached to long chains, expanding the utilization rate of adsorption sites. However, if the amount of humic acid solution is too small, it will reduce the number of active vacant sites on the surface of the humic acid-based composite material. Metal ions will penetrate into the interior of the humic acid-based composite material and complex with the effective components, which will reduce the utilization rate of adsorption sites.

[0047] The stability of soil aggregates reflects their water-holding capacity, erosion resistance, and permeability. Excessive application of humic acid composite remediation materials significantly reduced the content of large aggregates in sandy soil, making the aggregates more prone to breakage and decreasing stability. The content of iron-manganese oxide (Cd) significantly decreased, while the contents of ionic, weakly organic, and strongly organic Cd increased. The total Cd detection showed little change, indicating that excessive humic acid composite remediation materials actually reduced the ability to remove heavy metals and worsened the mechanical stability of soil aggregates. At a certain dosage, the soil aggregate content increased significantly with increasing material particle size. However, excessively large-particle-size humic acid composite remediation materials led to a significant increase in the content of silty sand-sized micro-aggregates, making the aggregates more prone to breakage and decreasing stability. Furthermore, different forms of Cd were enriched in the silty sand-sized micro-aggregates, resulting in higher Cd content in the soil samples. In conclusion, applying a small amount of humic acid composite remediation material with an appropriate particle size is beneficial for increasing the content of large aggregates in sandy soil, and this cementing agent helps enhance soil water stability and moisture retention.

[0048] In addition, the oxidizing functional groups such as phenolic hydroxyl and quinone groups in humic acid have a certain inhibitory effect on soil urease and nitrifying bacteria. Humic acid promotes the activity of microorganisms and enzymes in the soil, increases the number of aerobic bacteria, actinomycetes, and cellulose-decomposing bacteria, accelerates the mineralization of organic matter, and provides organic energy for soil microorganisms. As an electron acceptor for microbial respiration, humic acid can promote microbial growth, reproduction, and population diversity, and effectively degrade soil organic pollutants.

[0049] The advantages of this invention are:

[0050] (1) The humic acid composite remediation material of the present invention can effectively improve soil structure and quality;

[0051] (2) The humic acid composite remediation material of the present invention can effectively improve the efficiency of soil remediation. Detailed Implementation

[0052] The present invention will be further described clearly and in detail below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0053] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0054] Example 1

[0055] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0056] 1) Take 200g of lignite, 1L of 0.1mol / L NaOH solution and 10g of sodium pyrophosphate, mix them evenly, let them stand to obtain supernatant and solid. Take the supernatant, add 200mL of 0.5mol / L HCl solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0057] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0058] 3) Mix acrylic acid and humic acid solutions at a volume ratio of 1:0.5 to obtain a mixed solution. Separately, prepare butyl acrylate, cyclohexane, tristearyl sorbitan, and acetone at a dosage ratio of 1g:0.26g:0.03g:15mL. Heat the mixture to 50℃ and add it to the solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate and cyclohexane mixture. Maintain the temperature at 85℃ for 3 hours. While hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through a 100-mesh sieve to obtain the humic acid composite repair material.

[0059] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to 80 g / m³. 2 The humic acid remediation composite material of this invention is uniformly distributed. Its performance was tested in a natural environment after 60 days of remediation. The specific testing methods are as follows:

[0060] 1. Determination of heavy metal content in contaminated soil samples

[0061] Take 1g of the soil sample to be tested into a beaker, add 5mL of water to moisten it, then add 30mL of HCl, heat it on a hot plate to dry it, then add 10mL of HNO3 to the beaker, heat it on a hot plate to dry it, then add 10mL of HClO4 to the beaker and heat it on a hot plate until white smoke appears, remove it and cool it, add 1mL of HNO3, dilute it with water to 5mL, take 3 colorimetric tubes, add the digested soil sample to the mark, and perform heavy metal content determination. Repeat the experiment three times in parallel. The final Pb and Hg content of the sample is the average value of the three parallel experiments.

[0062] In addition, the cadmium ion content was determined by atomic absorption spectrophotometry. The contents of weakly and strongly organically bound Cd were determined by graphite furnace atomic absorption spectrophotometry, while the contents of other states were determined by flame atomic absorption spectrophotometry.

[0063] 2. Characterization of soil aggregates

[0064] 1) The particle size of soil aggregates was measured by electron microscopy.

[0065] 2) Water stability was tested using the hydrostatic method. The soil sample was air-dried, and 2 mL of water per gram of sample was sprayed onto the surface of the aggregates. The sample was then cured at room temperature for 1 day to ensure complete wetting. The sample was then re-sieved, selecting aggregates with a volume of approximately 4 cm³. 3 Add water to the saturated soil particles and continue adding water until the aggregates are completely submerged. Start timing when the aggregates are completely submerged. Record the number of particles that collapse per minute over 10 minutes and calculate the average of the three sets. The formula for calculating the water stability of the aggregates is as follows:

[0066] K=A×0.1+B×0.3+…+I×1.7+G×1.9+M×2.0

[0067] In the formula, K is the water stability coefficient of the aggregate; A, B, ... G are the number of particles that collapse per minute; and M is the number of particles that do not collapse after being submerged in water for 10 minutes.

[0068] The results are as follows.

[0069]

[0070] This invention uses lignite with a humic acid content exceeding 40 wt%, which is further purified to exceed 90 wt%. According to the results in the table, Hg in the exchangeable and reduced components combines with the humic acid composite remediation material prepared in this example to form a poorly soluble, insoluble, and stable complex, which can significantly reduce the available Hg content in the soil. The acid-treated humic acid composite remediation material has high porosity, enhancing its ability to adsorb heavy metal ions, and the complex has low environmental migration capacity, reducing bioimpact, indicating that this product can effectively improve soil remediation efficiency. Simultaneously, it can be seen that the treated soil sample formed sand-sized soil aggregates. Furthermore, with increasing material dosage, the material and small mineral molecules can cement together to form large soil aggregates, creating a relatively stable cross-linked network structure, thus gradually increasing soil water stability. Through a series of comparative experiments, this invention determined that 60–100 g / m³ is the optimal dosage. 2 The dosage of this invention provides better results when used.

[0071] Example 2

[0072] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0073] 1) Take 200g of lignite, 1L of 0.1mol / L NaOH solution and 10g of sodium pyrophosphate, mix them evenly, let them stand to obtain supernatant and solid. Take the supernatant, add 200mL of 0.5mol / L HCl solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0074] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0075] 3) Mix acrylic acid and humic acid solutions at a volume ratio of 1:0.5 to obtain a mixed solution. Separately, prepare butyl acrylate, cyclohexane, tristearyl sorbitan, and acetone at a dosage ratio of 1g:0.26g:0.03g:15mL. Heat the mixture to 50℃ and add it to the mixed solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate and cyclohexane mixture. Maintain the temperature at 85℃ for 3 hours. While hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through an 80-mesh sieve to obtain the humic acid composite repair material.

[0076] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to 80 g / m³. 2 The dosage of the humic acid remediation composite material of the present invention is evenly distributed. The performance of the soil after 60 days of remediation in a natural environment is tested in the same way as in Example 1. The results are as follows.

[0077]

[0078] According to the results in the table, at a certain dosage, the soil aggregate content increases significantly with the increase of material particle size, which obviously enhances the water stability of the soil sample. The humic acid composite remediation material in this example is rich in active groups, chelates with small molecules, and complexes with metal ions, significantly reducing the content of heavy metal ions.

[0079] Example 3

[0080] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0081] 1) Take 200g of lignite, 1L of 0.1mol / L NaOH solution and 10g of sodium pyrophosphate, mix them evenly, let them stand to obtain supernatant and solid. Take the supernatant, add 200mL of 0.5mol / L HCl solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0082] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0083] 3) Mix acrylic acid and humic acid solutions at a volume ratio of 1:0.5 to obtain a mixed solution. Separately, prepare butyl acrylate, cyclohexane, tristearyl sorbitan, and acetone at a dosage ratio of 1g:0.26g:0.03g:15mL. Heat the mixture to 50℃ and add it to the mixed solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate and cyclohexane mixture. Maintain the temperature at 85℃ for 3 hours. While hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through a 60-mesh sieve to obtain the humic acid composite repair material.

[0084] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to 80 g / m³. 2 The dosage of the humic acid remediation composite material of the present invention is evenly distributed. The performance of the soil after 60 days of remediation in a natural environment is tested in the same way as in Example 1. The results are as follows.

[0085]

[0086] According to the results in the table, the larger particle size of the humic acid composite remediation material significantly increased the content of silty sand-sized micro-soil aggregates, making the soil aggregates more prone to breakage and resulting in a decrease in water stability. Furthermore, based on Examples 2 and 3, it can be analyzed that the soil samples had a high Cd content due to the enrichment of different forms of Cd in the silty sand-sized micro-soil aggregates. Combining the results of Examples 1-3, this invention should incorporate a small amount of humic acid composite remediation material with an appropriate particle size, which is beneficial for increasing the content of large aggregates in sandy soil. This cementing agent helps enhance soil water stability and moisture content.

[0087] Example 4

[0088] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0089] 1) Take 200g of peat, 1L of 0.1mol / L NaOH solution and 10g of sodium pyrophosphate, mix them evenly, let them stand to obtain supernatant and solid. Take the supernatant, add 200mL of 0.5mol / L HCl solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0090] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0091] 3) Mix acrylic acid and humic acid solutions at a volume ratio of 1:0.5 to obtain a mixed solution. Separately, prepare butyl acrylate, cyclohexane, tristearyl sorbitan, and acetone at a dosage ratio of 1g:0.26g:0.03g:15mL. Heat the mixture to 50℃ and add it to the mixed solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate and cyclohexane mixture. Maintain the temperature at 85℃ for 3 hours. While hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through an 80-mesh sieve to obtain the humic acid composite repair material.

[0092] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to 80 g / m³. 2 The dosage of the humic acid remediation composite material of the present invention is evenly distributed. The performance of the soil after 60 days of remediation in a natural environment is tested in the same way as in Example 1. The results are as follows.

[0093]

[0094] Based on the results in the table and in conjunction with Example 2, it can be analyzed that the composite remediation material prepared by extracting humin from lignite in this invention has a strong adsorption and passivation effect on the heavy metal cadmium.

[0095] Comparative Example 1

[0096] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0097] 1) Take 200g of lignite and 1L of 0.1mol / L NaOH solution, mix them evenly, let them stand to obtain supernatant and solid. Take the supernatant, add 200mL of 0.5mol / L HCl solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0098] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0099] 3) Mix acrylic acid and humic acid solutions at a volume ratio of 1:0.5 to obtain a mixed solution. Separately, prepare butyl acrylate, cyclohexane, tristearyl sorbitan, and acetone at a dosage ratio of 1g:0.26g:0.03g:15mL. Heat the mixture to 50℃ and add it to the mixed solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate and cyclohexane mixture. Maintain the temperature at 85℃ for 3 hours. While hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through an 80-mesh sieve to obtain the humic acid composite repair material.

[0100] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to 80 g / m³. 2 The dosage of the humic acid remediation composite material of the present invention is evenly distributed. The performance of the soil after 60 days of remediation in a natural environment is tested in the same way as in Example 1. The results are as follows.

[0101]

[0102] This invention first obtains humic acid (brown humic acid) and fulvic acid, rich in functional groups such as carbonyl, carboxyl, and etheroxy groups, through leaching with dilute alkaline solution and acid-assisted precipitation. The combined humic acid, which is sparingly soluble in water but readily soluble in water, is complexed into water-soluble humate salts. Combined with sodium pyrophosphate, this significantly increases the humic acid extraction yield. In Example 2, the humic acid extraction yield was 17.2 wt%, with a purity far exceeding that of commercially available humic acid remediation materials. According to the results in the table and the characterization results, the humic acid extraction yield was only 8.4 wt%, clearly resulting in a significant decrease in the material's ability to remove heavy metals.

[0103] If we replace the HCl solution used in this example with a dilute sulfuric acid solution and perform the same test, according to the results in the table, the solution is rich in divalent metal ions, which will form a precipitate, reduce the purity of the humic acid product, and significantly decrease the material's ability to remove heavy metals.

[0104] Comparative Example 2

[0105] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0106] 1) Take 200g of lignite, 1L of 0.1mol / L NaOH solution and 10g of sodium pyrophosphate, mix them evenly, let stand to obtain supernatant and solid, take the supernatant, add 200mL of 0.5mol / L HNO3 solution to adjust the pH value of the system, filter to obtain humic acid solution.

[0107] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0108] 3) Mix acrylic acid and humic acid solutions at a volume ratio of 1:0.5 to obtain a mixed solution. Separately, prepare butyl acrylate, cyclohexane, tristearyl sorbitan, and acetone at a dosage ratio of 1g:0.26g:0.03g:15mL. Heat the mixture to 50℃ and add it to the mixed solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate and cyclohexane mixture. Maintain the temperature at 85℃ for 3 hours. While hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through an 80-mesh sieve to obtain the humic acid composite repair material.

[0109] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to 80 g / m³. 2 The dosage of the humic acid remediation composite material of the present invention is evenly distributed. The performance of the soil after 60 days of remediation in a natural environment is tested in the same way as in Example 1. The results are as follows.

[0110]

[0111]

[0112] Considering that substances such as sodium pyrophosphate have sodium cations, this example uses NaOH solution for alkaline dissolution. This experiment employs a "NaOH solution dissolution, HNO3 solution precipitation" method. Because HNO3 solution has strong oxidizing properties and can react with functional groups, the large humic acid molecules are degraded into smaller molecules. According to the results in the table, the treated soil sample has a small particle size and poor water stability.

[0113] Comparative Example 3

[0114] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0115] 1) Take 200g of lignite, 1L of 0.1mol / L NaOH solution and 10g of sodium pyrophosphate, mix them evenly, let them stand to obtain supernatant and solid. Take the supernatant, add 200mL of 0.5mol / L HCl solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0116] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0117] 3) Mix acrylic acid and humic acid solutions at a volume ratio of 1:0.5 to obtain a mixed solution. Separately, prepare butyl acrylate, tristearyl sorbitan, and acetone at a dosage ratio of 1g:0.03g:15mL. Heat the mixture to 50℃ and add it to the mixed solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate. Keep the mixture at 85℃ for 3 hours. While it is still hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through an 80-mesh sieve to obtain the humic acid composite repair material.

[0118] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to 80 g / m³. 2 The dosage of the humic acid remediation composite material of the present invention is evenly distributed. The performance of the soil after 60 days of remediation in a natural environment is tested in the same way as in Example 1. The results are as follows.

[0119]

[0120] Oxygen-containing functional groups such as epoxy groups are considered important surface functional groups for adsorbing heavy metal ions. They can form organic complexes with heavy metal ions. According to the results in the table, since the number of oxygen-containing functional groups on the surface of the humic acid-based composite material in this example is lower than that in Example 2, there are fewer adsorption sites. Pb, Hg, and Cd ions quickly occupy the adsorption sites provided by the surface of the humic acid-based composite material, forming insoluble metal complexes, which reduces the accumulation of heavy metals by soil organisms, but the effect is not as good as that of the material in Example 2.

[0121] Furthermore, based on the above results, the actual adsorption effect on Cd is significantly weakened. This is because the technical solution of the present invention introduces ring structure modification, which changes the adsorption sites of Cd, thereby significantly improving its adsorption capacity and adsorption amount.

[0122] Comparative Example 4

[0123] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0124] 1) Take 200g of lignite, 1L of 0.1mol / L NaOH solution and 10g of sodium pyrophosphate, mix them evenly, let them stand to obtain supernatant and solid. Take the supernatant, add 200mL of 0.5mol / L HCl solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0125] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0126] 3) Mix acrylic acid and humic acid solutions in a 1:1 volume ratio to obtain a mixed solution. Separately, prepare butyl acrylate, cyclohexane, tristearyl sorbitan, and acetone in a ratio of 1g:0.26g:0.03g:15mL. Heat the mixture to 50℃ and add it to the solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate and cyclohexane mixture. Maintain the temperature at 85℃ for 3 hours. While still hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through an 80-mesh sieve to obtain the humic acid composite repair material.

[0127] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to 80 g / m³. 2 The dosage of the humic acid remediation composite material of the present invention is evenly distributed. The performance of the soil after 60 days of remediation in a natural environment is tested in the same way as in Example 1. The results are as follows.

[0128]

[0129] A series of experiments revealed that as the amount of humic acid solution increased, the adsorption driving force of the material strengthened, and effective groups were incorporated into longer chains, expanding the utilization rate of adsorption sites. However, insufficient humic acid solution reduced the number of active vacant sites on the surface of the humic acid-based composite material, allowing metal ions to penetrate into the interior of the composite material and complex with the effective components, thus reducing the utilization rate of adsorption sites. According to the results in the table, the material's ability to remove heavy metals was significantly reduced.

[0130] Comparative Example 5

[0131] A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, the method comprising:

[0132] 1) Take 200g of lignite, 1L of 0.1mol / L NaOH solution and 10g of sodium pyrophosphate, mix them evenly, let them stand to obtain supernatant and solid. Take the supernatant, add 200mL of 0.5mol / L HCl solution to adjust the pH value of the system, and filter to obtain humic acid solution.

[0133] 2) Drying step 1) The solid obtained from the static operation is mixed with 5 mL of 1.5 mol / L HCl solution per gram of solid, filtered, and washed with distilled water until neutral. Then, 5 mL of 40 wt% HF solution is added per gram of solid for etching, filtered again, and washed with distilled water until neutral. The product is then dried to obtain the substrate.

[0134] 3) Mix acrylic acid and humic acid solutions at a volume ratio of 1:0.5 to obtain a mixed solution. Separately, prepare butyl acrylate, cyclohexane, tristearyl sorbitan, and acetone at a dosage ratio of 1g:0.26g:0.03g:15mL. Heat the mixture to 50℃ and add it to the mixed solution while stirring. Add 0.05g of potassium persulfate per gram of butyl acrylate and cyclohexane mixture. Maintain the temperature at 85℃ for 3 hours. While hot, add 1g of substrate per gram of organic raw material and mix well. After drying, grind and pass through an 80-mesh sieve to obtain the humic acid composite repair material.

[0135] Soil samples were taken from coal chemical contaminated sites for characterization, maintaining soil moisture at 60% and temperature at 20–25℃, according to a concentration of 120 g / m³. 2 The dosage of the humic acid remediation composite material of the present invention is evenly distributed. The performance of the soil after 60 days of remediation in a natural environment is tested in the same way as in Example 1. The results are as follows.

[0136]

[0137] According to the results in the table, adding excessive amounts of humic acid composite remediation material significantly reduced the content of large aggregates in sandy soil, making the soil aggregates more prone to breakage and decreasing their stability. The content of iron and manganese oxide (Cd) significantly decreased, while the content of ionic, weakly organic, and strongly organic Cd increased, with little change in the total Cd detection amount. Excessive humic acid composite remediation material actually led to a decrease in the ability to remove heavy metals and a deterioration in the mechanical stability of soil aggregates. This is mainly because the mobility of the remediation material in contaminated soil changed, causing it to form aggregates or precipitates, reducing its binding with the soil, and significantly impacting the binding form of Cd.

Claims

1. A method for preparing a humic acid composite remediation material for coal chemical contaminated sites, characterized in that, The method includes: 1) Take the raw materials, alkali solution and phosphide, mix them evenly, let them stand, take the supernatant, add acid solution to adjust the pH value of the system, and filter to obtain humic acid solution. 2) Drying step 1) The solid obtained from the static operation is mixed with acid solution, filtered and washed, then corroded with strong acid, filtered and washed again, and dried to obtain the substrate; 3) Take organic raw materials, emulsifiers, and solvents, heat them, and while stirring, add a mixture of acyclic carboxylic acid and humic acid solution, add an initiator, and after thermal reaction, add the hot substrate and mix evenly. After drying and grinding, obtain humic acid composite repair material. Step 1) The raw material is low-quality coal; The low-quality coal is lignite and / or weathered coal. Step 1) The phosphide is sodium pyrophosphate; Step 2) The acid solution is a 0.1–0.5 mol / L HCl aqueous solution; Step 2) The strong acid is a 35-45 wt% aqueous HF solution; Step 3) The organic raw materials are butyl acrylate and cyclohexane; The solvent in step 3) is acetone; Step 3) The acyclic carboxylic acid is acrylic acid.

2. The method for preparing a humic acid composite remediation material for coal chemical contaminated sites according to claim 1, characterized in that, Step 1) The alkaline solution is a 0.1-0.5 mol / L NaOH aqueous solution, and the amount used is 5.0-10.0 mL / g of raw material; The amount of phosphide used is 0.05 to 0.10 g / g of raw material.

3. A method for preparing a humic acid composite remediation material for coal chemical contaminated sites according to claim 1 or 2, characterized in that, Step 1) The amount of acid used is 1.0 to 1.5 mL / g of raw material.

4. The method for preparing a humic acid composite remediation material for coal chemical contaminated sites according to claim 1, characterized in that, In step 2), the product is washed with distilled water until it becomes neutral. Step 2) The amount of strong acid used is 5-10 mL / g of the solid obtained in step 1).

5. The method for preparing a humic acid composite remediation material for coal chemical contaminated sites according to claim 1, characterized in that, In step 3), the mass ratio of butyl acrylate to cyclohexane in the organic raw material is 1:(0.2-0.3). The emulsifier is tristearate sorbitan, and its dosage is 0.01-0.05 g / g organic raw material; The solvent dosage is 15–25 mL / g organic raw material; Step 3) describes the heating process, where the temperature is raised to 50–60 °C.

6. The method for preparing a humic acid composite remediation material for coal chemical contaminated sites according to claim 1, characterized in that, In step 3), the mixture of acyclic carboxylic acid and humic acid solutions: The acyclic carboxylic acid and humic acid solution were prepared and mixed evenly at a volume ratio of 1:(0.5-0.7).

7. The method for preparing a humic acid composite remediation material for coal chemical contaminated sites according to claim 1, characterized in that, Step 3) The initiator is potassium persulfate, and its dosage is 0.05-0.1 g / g organic raw material; The thermal reaction described in step 3) is carried out at 80–90 °C for 2–5 h at a constant temperature.

8. A method for preparing a humic acid composite remediation material for coal chemical contaminated sites according to claim 1 or 7, characterized in that, Step 3) The substrate is added at a ratio of 0.9 to 1.1 g per gram of organic raw material.

9. The method for preparing a humic acid composite remediation material for coal chemical contaminated sites according to claim 1, characterized in that, Step 3) involves grinding the material and then passing it through a 60-100 mesh sieve.

10. A humic acid composite remediation material for coal chemical contaminated sites, prepared by any one of claims 1 to 9.

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