CN115490819B - Modifier based on heavy metal contaminated soil and preparation method thereof - Google Patents
Modifier based on heavy metal contaminated soil and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a modifier based on heavy metal contaminated soil, which comprises the following raw materials: acrylamide, acryloyloxyethyl trimethyl ammonium chloride, glutaconic acid, crosslinking system solution, mesoporous silica microsphere, SDBS emulsifier, industrial residue and perphosphate. The invention discloses a preparation method of the modifier based on heavy metal contaminated soil, which comprises the following steps: adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into deionized water, stirring, dripping a crosslinking system solution, continuously stirring, and standing to obtain an acrylamide compound; adding mesoporous silica microspheres and an SDBS emulsifier into the acrylamide compound, stirring, dropwise adding a crosslinking system solution in the stirring process, refluxing and stirring, cooling to room temperature, washing, and vacuum drying to obtain grafted mesoporous silica microspheres; and adding industrial waste residue and perphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal polluted soil.
Description
Technical Field
The invention relates to the technical field of soil improvement, in particular to a modifier based on heavy metal polluted soil and a preparation method thereof.
Background
The acid soil refers to the soil with pH of the cultivated layer soil less than 6.6, and the formation reasons are mainly rapid mineralization of soil organic matters and high-strength leaching of potassium, calcium and other salt ions. In addition, with the acceleration of the global industrialization process, acid soil is counted to account for about 50% of the arable soil in the world. Acidic soil has the disadvantages of low pH and low organic content, and thus improvement is needed. At present, lime is adopted to improve the acid soil to be a conventional means, so that the pH of the acid soil can be quickly increased, but long-term or large-amount lime use can cause hardening of the acid soil, decrease the microbial activity and cause imbalance of element balance of the acid soil.
At present, a large amount of mineral resources are distributed in China, a large amount of heavy metals flow out due to mine development, the heavy metal pollution of the industrial polluted site soil is characterized by a large amount of heavy metal species, high content, high acidity and the like, and the effective state concentration of the heavy metals is higher due to low pH value and low organic matter content in the acid soil, so that the migration capability is strong, and the safety production of crops is seriously threatened. Therefore, the pollution repair of heavy metals in acid soil is imperative and urgent.
At present, the repair method for the polluted soil mainly comprises in-situ repair and ex-situ repair. Ectopic repair is a method for treating polluted soil by a plurality of methods such as cleaning, incineration treatment, heat treatment, a bioreactor and the like by a chemical physical method after digging out, and is a method commonly used in early stage. In situ repair is popular because it does not involve digging and transporting earth. General in-situ repair methods such as a soil-adsorbing method, a precipitation method, a leaching method, an electrochemical method, a magnetization method and the like. The in-situ matrix improvement technology has the advantages of low cost, quick response, no damage to soil structure, easy implementation, suitability for large-area popularization and the like.
In recent years, biomass charcoal has been widely paid attention to improving acid soil, improving acid soil fertility, improving acid soil physical structure, reducing acid soil nutrient leaching, enhancing acid soil microbial activity and promoting acid soil nutrient circulation, but the effect of improving acid soil pH by biomass charcoal is weak. Therefore, based on the current situation of heavy metal pollution of acid soil in China and the defects of the prior art, it is necessary to develop a simple, low-cost and high-efficiency improved material, and meanwhile, the repair of heavy metal and the improvement of acid soil are realized, and the effect of slow release can be played for a long time, so that the material becomes the focus of attention of environmental protection and technology workers.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides a modifier based on heavy metal polluted soil and a preparation method thereof.
An improver based on heavy metal contaminated soil, which comprises the following raw materials: acrylamide, acryloyloxyethyl trimethyl ammonium chloride, glutaconic acid, crosslinking system solution, mesoporous silica microspheres, SDBS emulsifier, industrial waste residue and perphosphate; the mass ratio of the acrylamide, the acryloyloxyethyl trimethyl ammonium chloride, the glutaconic acid, the crosslinking system solution, the mesoporous silica microspheres, the SDBS emulsifier, the industrial waste residue and the perphosphate is 10-20:20-40:5-15:11.11-22.6:10-20:1-3:5-15:1-10.
Preferably, the crosslinking system solution comprises a crosslinking system and deionized water according to a mass ratio of 1.11-2.6:10-20 parts.
Preferably, the crosslinking system comprises: the mass ratio of the potassium persulfate to the sodium bisulphite to the V-50 initiator is 1-2:0.1-0.5:0.01-0.1.
The crosslinking system adopts potassium persulfate as an oxidant, and is compounded with sodium bisulfate, so that the sodium bisulfate can effectively promote the thermal decomposition of the potassium persulfate and generate a free radical intermediate, but the low concentration of the later-stage free radicals can not break the intermolecular shielding effect due to the excessively rapid consumption of the earlier-stage free radicals, so that the continuous progress of the polymerization process is hindered, and the defect of the concentration of the later-stage free radicals can be effectively overcome by further compounding with the action of a V-50 initiator.
Preferably, the mesoporous silica microspheres have a particle size of 5-15 μm.
Preferably, the perphosphate is superphosphate.
Preferably, the industrial waste residue is at least one of alkali residue, phosphogypsum, blast furnace slag, fly ash and tailing sand.
The preparation method of the modifier based on the heavy metal contaminated soil comprises the following steps:
(1) Adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into deionized water, uniformly stirring, regulating the pH of the system to 5-6, regulating the temperature to 10-30 ℃, dropwise adding a crosslinking system solution under the protection of nitrogen, continuously stirring for 10-20min after the dropwise adding is completed, and standing for 1-3h to obtain an acrylamide compound;
(2) Adding mesoporous silica microspheres and an SDBS emulsifier into the acrylamide compound, stirring for 5-15min, dropwise adding a crosslinking system solution in the stirring process, refluxing and stirring for 10-20min at 60-80 ℃, cooling to room temperature, washing, and vacuum drying to obtain grafted mesoporous silica microspheres;
(3) And adding industrial waste residue and perphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal polluted soil.
Preferably, in step (1), the pH of the system is adjusted to 5-6 with hydrochloric acid having a concentration of 0.5-1.5 mol/L.
Preferably, the mass ratio of the crosslinking system solution used in step (1) to the crosslinking system solution used in step (2) is 60-80:20-40.
Preferably, in step (2), the product is washed with absolute ethanol.
The technical effects of the invention are as follows:
the invention adopts acrylamide, glutaconic acid and acryloyloxyethyl trimethyl ammonium chloride as raw materials, and prepares the acrylamide compound by aqueous solution polymerization, wherein the dicarboxylic structure of the glutaconic acid has repulsive force between static electricity, so that molecular chains are stretched in the polymerization process, the comprehensive effect ensures that the flocculation effect of the system is excellent, and anions and cations are combined on the molecular long chains of the acrylamide compound; further, mesoporous silica microspheres are used as grafting substrates, and because the mesoporous silica microspheres contain hydrophilic groups, under the action of a crosslinking system solution, the acrylamide compound is grafted on the surfaces of the mesoporous silica microspheres to form the modifier, so that the modifier has an excellent adsorption effect on heavy metal ions, and can wrap heavy metal phosphate, hydroxide and other precipitates, thereby greatly enhancing the solidification effect of the heavy metal.
Meanwhile, the grafted mesoporous silica microsphere has extremely high and low temperature resistance, excellent hydrolysis resistance in an acidic environment and extremely strong hydrophilic water retention performance; the industrial waste residue can dissolve calcium oxide and hydrate to form calcium hydroxide, and further forms hydroxyapatite crystals with calcium superphosphate under the action of water, so that the Cd, cu, hg, zn, pb heavy metal can be effectively complexed, the solubility of the complexing product is low under the acidic condition, the solubility of the complexing product is tens of orders of magnitude lower than that of hydroxide, and the solidifying effect is extremely stable.
The invention effectively utilizes industrial waste residue raw materials, is environment-friendly, effectively improves the utilization value of industrial waste residues, changes waste into valuable, can effectively repair and improve acidic heavy metal polluted soil, realizes the efficient fixation of heavy metals in soil, can improve the negative effects of soil hardening and the like caused by acidic soil, and simultaneously can effectively play a role in slow release of the silica microsphere carrier with developed hollow structure in the modifier, can play a role in continuously adsorbing and improving the acidic soil, can effectively inhibit the desorption of the adsorbed heavy metals, and further increases the durability of the solidified matters.
Drawings
Fig. 1 is a graph showing comparison of nitrogen adsorption-desorption isotherms before and after the modifier based on heavy metal contaminated soil obtained in example 5 was left to stand in an acidic environment (ph=5.5) for 24 hours.
Detailed Description
The invention is further illustrated below in connection with specific embodiments.
Example 1
An improver based on heavy metal contaminated soil, which comprises the following raw materials: 10kg of acrylamide, 20kg of acryloyloxyethyl trimethyl ammonium chloride, 5kg of glutaconic acid, 11.11kg of crosslinking system solution, 10kg of mesoporous silica microspheres with the particle size of 5-15 mu m, 1kg of SDBS emulsifier, 5kg of phosphogypsum and 1kg of superphosphate.
The crosslinking system solution is prepared by adding 1kg of potassium persulfate, 0.1kg of sodium bisulphite and 0.01kg kgV-50 of initiator into 10kg of deionized water and uniformly stirring.
The preparation method of the modifier based on the heavy metal contaminated soil comprises the following steps:
(1) Adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into 50kg deionized water, uniformly stirring, adopting hydrochloric acid with the concentration of 0.5mol/L to adjust the pH value of the system to 5-6, adjusting the temperature to 10 ℃, dropwise adding 60% of crosslinking system solution under the protection of nitrogen, continuously stirring for 10min after the dropwise adding is complete, and standing for 1h to obtain an acrylamide compound;
(2) Adding mesoporous silica microspheres and an SDBS emulsifier into an acrylamide compound, stirring at 600r/min for 5min, dripping the rest crosslinking system solution in the stirring process, refluxing and stirring at 60 ℃ for 10min, cooling to room temperature, washing the product by using absolute ethyl alcohol, and vacuum drying to obtain grafted mesoporous silica microspheres;
(3) And adding phosphogypsum and calcium superphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal contaminated soil.
Example 2
An improver based on heavy metal contaminated soil, which comprises the following raw materials: 20kg of acrylamide, 40kg of acryloyloxyethyl trimethyl ammonium chloride, 15kg of glutaconic acid, 22.6kg of crosslinking system solution, 20kg of mesoporous silica microspheres with the particle size of 5-15 mu m, 3kg of SDBS emulsifier, 15kg of phosphogypsum and 10kg of superphosphate.
The crosslinking system solution is obtained by adding 2kg of potassium persulfate, 0.5kg of sodium bisulphite and 0.1-kgV-50 initiator into 20kg of deionized water and uniformly stirring.
The preparation method of the modifier based on the heavy metal contaminated soil comprises the following steps:
(1) Adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into 100kg deionized water, uniformly stirring, adopting hydrochloric acid with the concentration of 1.5mol/L to adjust the pH of the system to 5-6, adjusting the temperature to 30 ℃, dropwise adding 80% of crosslinking system solution under the protection of nitrogen, continuously stirring for 20min after the dropwise adding is complete, and standing for 3h to obtain an acrylamide compound;
(2) Adding mesoporous silica microspheres and an SDBS emulsifier into an acrylamide compound, stirring at a speed of 1000r/min for 15min, dripping the rest crosslinking system solution in the stirring process, refluxing and stirring at a temperature of 80 ℃ for 20min, cooling to room temperature, washing the product by using absolute ethyl alcohol, and vacuum drying to obtain grafted mesoporous silica microspheres;
(3) And adding phosphogypsum and calcium superphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal contaminated soil.
Example 3
An improver based on heavy metal contaminated soil, which comprises the following raw materials: 12kg of acrylamide, 35kg of acryloyloxyethyl trimethyl ammonium chloride, 8kg of glutaconic acid, 15.97kg of crosslinking system solution, 17kg of mesoporous silica microspheres with the particle size of 5-15 mu m, 1.5kg of SDBS emulsifier, 13kg of tailing sand and 4kg of superphosphate.
The crosslinking system solution is obtained by adding 1.7kg of potassium persulfate, 0.2kg of sodium bisulphite and 0.07kgV-50 initiator into 14kg of deionized water and uniformly stirring.
The preparation method of the modifier based on the heavy metal contaminated soil comprises the following steps:
(1) Adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into 90kg deionized water, uniformly stirring, adopting hydrochloric acid with the concentration of 0.8mol/L to adjust the pH of the system to 5-6, adjusting the temperature to 25 ℃, dropwise adding 65% of crosslinking system solution under the protection of nitrogen, continuously stirring for 17min after the dropwise adding is completed, and standing for 1.5h to obtain an acrylamide compound;
(2) Adding mesoporous silica microspheres and an SDBS emulsifier into an acrylamide compound, stirring at a speed of 900r/min for 7min, dripping the rest crosslinking system solution in the stirring process, refluxing and stirring at a temperature of 75 ℃ for 12min, cooling to room temperature at a stirring speed of 170r/min, washing the product by using absolute ethyl alcohol, and vacuum drying to obtain grafted mesoporous silica microspheres;
(3) And adding tailing sand and calcium superphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal contaminated soil.
Example 4
An improver based on heavy metal contaminated soil, which comprises the following raw materials: 18kg of acrylamide, 25kg of acryloyloxyethyl trimethyl ammonium chloride, 12kg of glutaconic acid, 17.73kg of crosslinking system solution, 13kg of mesoporous silica microspheres with the particle size of 5-15 mu m, 2.5kg of SDBS emulsifier, 7kg of blast furnace slag and 8kg of superphosphate.
The crosslinking system solution is obtained by adding 1.3kg of potassium persulfate, 0.4kg of sodium bisulphite and 0.03kg kgV-50 of initiator into 16kg of deionized water and uniformly stirring.
The preparation method of the modifier based on the heavy metal contaminated soil comprises the following steps:
(1) Adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into 70kg deionized water, uniformly stirring, adopting hydrochloric acid with the concentration of 1.2mol/L to adjust the pH of the system to 5-6, adjusting the temperature to 15 ℃, dropwise adding 75% of crosslinking system solution under the protection of nitrogen, continuously stirring for 13min after the dropwise adding is completed, and standing for 2.5h to obtain an acrylamide compound;
(2) Adding mesoporous silica microspheres and an SDBS emulsifier into an acrylamide compound, stirring at a speed of 700r/min for 13min, dripping the rest crosslinking system solution in the stirring process, refluxing and stirring at a temperature of 65 ℃ for 18min, cooling to room temperature, washing the product by using absolute ethyl alcohol, and vacuum drying to obtain grafted mesoporous silica microspheres;
(3) And adding blast furnace slag and calcium superphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal contaminated soil.
Example 5
An improver based on heavy metal contaminated soil, which comprises the following raw materials: 15kg of acrylamide, 30kg of acryloyloxyethyl trimethyl ammonium chloride, 10kg of glutaconic acid, 16.85kg of crosslinking system solution, 15kg of mesoporous silica microspheres with the particle size of 5-15 mu m, 2kg of SDBS emulsifier, 10kg of blast furnace slag and 6kg of superphosphate.
The crosslinking system solution is obtained by adding 1.5kg of potassium persulfate, 0.3kg of sodium bisulphite and 0.05kgV-50 initiator into 15kg of deionized water and uniformly stirring.
The preparation method of the modifier based on the heavy metal contaminated soil comprises the following steps:
(1) Adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into 80kg deionized water, uniformly stirring, adopting hydrochloric acid with the concentration of 1mol/L to adjust the pH of the system to 5-6, adjusting the temperature to 20 ℃, dropwise adding 70% of crosslinking system solution under the protection of nitrogen, continuously stirring for 15min after the dropwise adding is complete, and standing for 2h to obtain an acrylamide compound;
(2) Adding mesoporous silica microspheres and an SDBS emulsifier into an acrylamide compound, stirring at a speed of 800r/min for 10min, dripping the rest crosslinking system solution in the stirring process, refluxing and stirring at a temperature of 70 ℃ for 15min, cooling to room temperature, washing the product by using absolute ethyl alcohol, and vacuum drying to obtain grafted mesoporous silica microspheres;
(3) And adding blast furnace slag and calcium superphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal contaminated soil.
The modifier obtained in this example was allowed to stand in an acidic environment (ph=5.5) for 24 hours, and was subjected to nitrogen adsorption-desorption isotherm comparison before and after the standing, as shown in fig. 1, the modifier obtained in this example was excellent in adsorption effect before the standing, and still had a strong adsorption effect after the standing.
The results show that the modifier obtained by the embodiment has extremely strong adsorption effect, can realize slow release effect and can improve acid soil for a long time; on the other hand, the modifier obtained by the embodiment has developed pore structure, and the capacity of passivating the biological effective state heavy metal is gradually enhanced along with the gradual release of pore contents, and meanwhile, soil organic matters and the like can be increased, so that the soil acidification process is relieved. Therefore, the material of the invention can repair and improve the acid soil polluted by heavy metal for a long time and high efficiency.
The applicant believes that the mesoporous silica microsphere is taken as a grafting substrate, and the mesoporous silica microsphere contains hydrophilic groups, so that the acrylamide compound is grafted on the surface of the mesoporous silica microsphere to form the modifier under the action of a crosslinking system solution, so that the modifier has excellent adsorption effect on heavy metal ions, and can wrap heavy metal phosphate, hydroxide and other precipitates, thereby greatly enhancing the curing effect on the heavy metal.
Comparative example 1
A heavy metal polluted soil modifier comprises the following raw materials: 55kg of methyl acrylate, 5.055kg of crosslinking system solution, 15kg of mesoporous silica microspheres with the particle size of 5-15 mu m, 2kg of SDBS emulsifier, 10kg of blast furnace slag and 6kg of calcium superphosphate.
The crosslinking system solution is obtained by adding 1.5kg of potassium persulfate, 0.3kg of sodium bisulphite and 0.05kgV-50 initiator into 15kg of deionized water and uniformly stirring.
The preparation method of the heavy metal contaminated soil modifier comprises the following steps:
(1) Adding mesoporous silica microspheres and an SDBS emulsifier into methyl acrylate, stirring at a speed of 800r/min for 10min, dripping the rest crosslinking system solution in the stirring process, refluxing and stirring at a temperature of 70 ℃ for 15min, cooling to room temperature, washing the product by using absolute ethyl alcohol, and vacuum drying to obtain grafted mesoporous silica microspheres;
(2) And adding blast furnace slag and calcium superphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the heavy metal contaminated soil modifier.
Comparative example 2
A heavy metal polluted soil modifier comprises the following raw materials: 15kg of mesoporous silica microspheres with the particle size of 5-15 mu m, 10kg of blast furnace slag and 6kg of calcium superphosphate.
The preparation method of the heavy metal contaminated soil modifier comprises the following steps: and adding blast furnace slag and calcium superphosphate into the mesoporous silica microspheres, and uniformly mixing to obtain the heavy metal contaminated soil modifier.
Selecting a metal polluted land around a heavy coal mine, then carrying out first ploughing, wherein the ploughing depth is not less than 20cm, immediately watering, carrying out second ploughing, finishing into a square soil with furrows, taking a sample point every 100m, selecting 10 samples, detecting the heavy metal content, the effective N, the effective P, the effective K and the organic matter content of the sample point, repeatedly measuring twice, and taking the average value as the heavy metal content of the test area.
The modifier obtained in example 5 and comparative examples 1-2 (the mass ratio of modifier to soil is 8:100) was then uniformly dispersed into the above soil according to different areas, and aged, thus completing soil pollution control. And then continuously and respectively measuring the heavy metal content, the effective N, the effective P, the effective K and the organic matter content according to the method.
| Raw soil | Example 5 | Comparative example 1 | Comparative example 2 | |
| pH | 5.5 | 7.5 | 6.4 | 6.0 |
| Hg，mg/kg | 0.47 | 0.17 | 0.25 | 0.31 |
| Cd，mg/kg | 0.45 | 0.15 | 0.20 | 0.33 |
| Pb，mg/kg | 78.7 | 39.6 | 43.9 | 50.7 |
| Cu，mg/kg | 46.5 | 32.1 | 37.7 | 40.6 |
| Quick-acting N, mg/kg | 15 | 35 | 31 | 26 |
| Quick-acting P, mg/kg | 357 | 457 | 422 | 403 |
| Quick-acting K, mg/kg | 316 | 389 | 370 | 337 |
| Organic matters, g/kg | 6.4 | 8.7 | 7.7 | 6.9 |
From the above table, it can be seen that: the modifier provided by the invention can effectively improve the pH value of the acidic heavy metal polluted soil, so that the acidic heavy metal polluted soil is close to neutral, and the soil is beneficial to restoration. And the heavy metal content in the soil after ageing is obviously reduced, and meanwhile, after the soil fertility is improved by the modifier, the quick-acting N, quick-acting P, quick-acting K and organic matter content are obviously improved, which indicates that the soil fertility is obviously improved.
The applicant believes that: the grafted mesoporous silica microsphere has extremely high and low temperature resistance, excellent hydrolysis resistance in an acidic environment and extremely strong hydrophilic water retention performance; the industrial waste residue can dissolve calcium oxide and hydrate to form calcium hydroxide, and further forms hydroxyapatite crystals with calcium superphosphate under the action of water, so that the Cd, cu, hg, zn, pb heavy metal can be effectively complexed, the solubility of the complexing product is low under the acidic condition, the solubility of the complexing product is tens of orders of magnitude lower than that of hydroxide, and the solidifying effect is extremely stable.
The modifier can effectively repair and improve the acidic heavy metal polluted soil, realize the efficient fixation of heavy metals in the soil, improve the negative effects of soil hardening and the like caused by the acidic soil, and simultaneously realize the slow release effect of the silica microsphere carrier with developed hollow structure in the modifier, thereby realizing the effects of continuous adsorption and improvement of the acidic soil, effectively inhibiting the desorption effect of the adsorbed heavy metals and further improving the durability of the solidified matters.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (10)
1. The modifier based on the heavy metal contaminated soil is characterized by comprising the following raw materials: acrylamide, acryloyloxyethyl trimethyl ammonium chloride, glutaconic acid, crosslinking system solution, mesoporous silica microspheres, SDBS emulsifier, industrial waste residue and perphosphate; the mass ratio of the acrylamide, the acryloyloxyethyl trimethyl ammonium chloride, the glutaconic acid, the crosslinking system solution, the mesoporous silica microspheres, the SDBS emulsifier, the industrial waste residue and the perphosphate is 10-20:20-40:5-15:11.11-22.6:10-20:1-3:5-15:1-10;
the modifier is prepared by the following steps:
(1) Adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into deionized water, uniformly stirring, regulating the pH of the system to 5-6, regulating the temperature to 10-30 ℃, dropwise adding a crosslinking system solution under the protection of nitrogen, continuously stirring for 10-20min after the dropwise adding is completed, and standing for 1-3h to obtain an acrylamide compound;
(2) Adding mesoporous silica microspheres and an SDBS emulsifier into the acrylamide compound, stirring for 5-15min, dropwise adding a crosslinking system solution in the stirring process, refluxing and stirring for 10-20min at 60-80 ℃, cooling to room temperature, washing, and vacuum drying to obtain grafted mesoporous silica microspheres;
(3) And adding industrial waste residue and perphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal polluted soil.
2. The modifier based on heavy metal contaminated soil according to claim 1, wherein the crosslinking system solution comprises a crosslinking system and deionized water in a mass ratio of 1.11-2.6:10-20 parts.
3. The modifier for soil contaminated with heavy metals according to claim 2, wherein the crosslinking system comprises: the mass ratio of the potassium persulfate to the sodium bisulphite to the V-50 initiator is 1-2:0.1-0.5:0.01-0.1.
4. The modifier for soil polluted by heavy metal according to claim 1, wherein the mesoporous silica microspheres have a particle size of 5 to 15 μm.
5. The modifier for soil polluted by heavy metals as claimed in claim 1, wherein the perphosphate is superphosphate.
6. The modifier for heavy metal contaminated soil according to claim 1, wherein the industrial waste residue is at least one of alkali residue, phosphogypsum, blast furnace slag, fly ash and tailing sand.
7. A method for preparing the modifier based on heavy metal contaminated soil according to any one of claims 1 to 6, comprising the steps of:
(1) Adding acrylamide, acryloyloxyethyl trimethyl ammonium chloride and glutaconic acid into deionized water, uniformly stirring, regulating the pH of the system to 5-6, regulating the temperature to 10-30 ℃, dropwise adding a crosslinking system solution under the protection of nitrogen, continuously stirring for 10-20min after the dropwise adding is completed, and standing for 1-3h to obtain an acrylamide compound;
(2) Adding mesoporous silica microspheres and an SDBS emulsifier into the acrylamide compound, stirring for 5-15min, dropwise adding a crosslinking system solution in the stirring process, refluxing and stirring for 10-20min at 60-80 ℃, cooling to room temperature, washing, and vacuum drying to obtain grafted mesoporous silica microspheres;
(3) And adding industrial waste residue and perphosphate into the grafted mesoporous silica microspheres, and uniformly mixing to obtain the modifier based on heavy metal polluted soil.
8. The method for preparing a modifier based on heavy metal contaminated soil according to claim 7, wherein in the step (1), the pH of the system is adjusted to 5-6 by using hydrochloric acid with a concentration of 0.5-1.5 mol/L.
9. The method for preparing the modifier based on the heavy metal contaminated soil according to claim 7, wherein the mass ratio of the crosslinking system solution used in the step (1) to the crosslinking system solution used in the step (2) is 60-80:20-40.
10. The method for preparing a modifier for soil polluted by heavy metals as claimed in claim 7, wherein in step (2), the product is washed with absolute ethanol.
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