CN111286341A - Solidification enhancer and preparation method and application thereof - Google Patents
Solidification enhancer and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a preparation method of a solidification enhancer, which comprises the following steps: 1) mixing graphite powder and diatomite powder to obtain graphite silicon powder; 2) mixing phosphoric acid and sulfuric acid solution, and uniformly stirring to obtain a sulfur-phosphorus mixed acid solution; 3) mixing the graphite silicon powder and the sulfur-phosphorus mixed acid liquor, and uniformly stirring to obtain silicon-ink mixed acid slurry; 4) performing low-temperature plasma irradiation on the mixed acid pulp for 30-60 minutes to obtain a graphene-poly-silicon-phosphorus mixed colloid; 5) and mixing the gamma-mercaptopropyl trimethoxy silane and the graphene-polysilicon mixed colloid, uniformly stirring, aging for 6-12 hours, drying, and grinding to obtain the curing enhancer. The preparation method is simple, and the sources of the required raw materials are wide. The curing enhancer prepared by the invention is added into the traditional curing material by 5 percent, so that the leaching concentration of heavy metal in the cured body can be effectively reduced, and the uniaxial compressive strength, acid resistance and thawing resistance of the cured body can be effectively improved.
Description
Technical Field
The invention relates to the field of treatment of heavy metal contaminated soil, in particular to a solidification enhancer and a preparation method and application thereof.
Background
In China, with the expansion development of industry, the social problem caused by heavy metal soil pollution is easy to be prominent. Heavy metal pollution presents a significant challenge to the health of local residents. Heavy metals have strong biological activity and can be enriched in human bodies through a biological uptake-biological chain transfer path. Heavy metals are extremely harmful to human health and are difficult to drain from the human body by means of biological metabolism. For example, cadmium can accumulate in internal organs of the human body, leading to osteoporosis and inducing cancer. Hexavalent chromium is a carcinogen and is easily absorbed by multiple organs of the human body, and can induce lung cancer seriously. Mercury causes irreversible damage to the body's organs and central nervous system after entering the body. Lead can cause neurological dysfunction and lead to anemia and kidney damage after entering the human body.
At present, three ideas of natural attenuation, isolation and restoration exist for the treatment of heavy metal contaminated soil. The solidification and stabilization method is considered to be one of the most important methods for repairing heavy metal contaminated soil, and has the advantages of convenience in operation, economic benefit, complete technical specification and the like. The solidification and stabilization technology generally mixes and stirs cementing materials such as cement and the like with the heavy metal contaminated soil to induce hydration reaction, so as to promote the absorption and the wrapping of hydration products on the heavy metal contaminants. It is worth noting that the problems of low strength of solidified bodies, high leaching rate of heavy metals, and poor acid resistance and thawing resistance of the solidified bodies still exist when the solidification stabilization technology is used for treating polluted soil containing various heavy metals and high content of the heavy metals. The industry has been to incorporate materials such as fly ash, blast furnace slag, silica fume, bentonite, etc. into cement to provide cement setting properties. However, it is still difficult to effectively treat high-concentration and multi-metal contaminated soil in this way, and it is difficult to achieve significant improvement of multiple indexes.
Therefore, there is a need to develop a solidification enhancer to replace the conventional admixtures for achieving an effective solidification treatment of high-concentration, multi-metal contaminated soil.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to solve the technical problem of providing a preparation method of a solidification enhancer.
The invention also aims to solve the technical problem of providing a solidification enhancer and application thereof.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for preparing a solidification enhancer comprises the following steps:
1) mixing graphite powder and diatomite powder to obtain graphite silicon powder;
2) mixing phosphoric acid and sulfuric acid solution, and uniformly stirring to obtain a sulfur-phosphorus mixed acid solution;
3) mixing the graphite silicon powder and the sulfur-phosphorus mixed acid liquor, and uniformly stirring to obtain silicon-ink mixed acid slurry;
4) performing low-temperature plasma irradiation on the silicon ink mixed acid pulp for 30-60 minutes to obtain a graphene-poly-silicon-phosphorus mixed colloid;
5) and mixing the gamma-mercaptopropyl trimethoxy silane and the graphene-polysilicon mixed colloid, uniformly stirring, aging for 6-12 hours, drying, and grinding to obtain the curing enhancer.
Wherein the mass ratio of the graphite powder to the diatomite powder in the step 1) is 1-3: 10.
Wherein, the volume ratio of the phosphoric acid solution to the sulfuric acid solution in the step 2) is 1-2: 1; the concentration of the sulfuric acid solution is 2-6M.
Wherein the solid-to-liquid ratio of the graphite silicon powder and the sulfur-phosphorus mixed acid liquid in the step 3) is 1: 1-2 mg/mL.
Wherein, the irradiation action voltage of the low-temperature plasma in the step 4) is 20-100 KV, and the action atmosphere of the low-temperature plasma is oxygen.
The volume ratio of the gamma-mercaptopropyl trimethoxy silane to the graphene-phosphorus polysilicate mixed colloid in the step 5) is 1-2: 10.
The invention also discloses a curing enhancer prepared by the preparation method.
The invention also comprises the application of the solidification enhancer in the treatment of the polluted soil.
Wherein the polluted soil is heavy metal polluted soil.
Wherein the heavy metal is one or more of mercury, cadmium or arsenic.
The reaction mechanism is as follows: in the process of irradiating the silicon ink mixed acid slurry by low-temperature plasma, high-energy electrons released by a high-voltage electrode impact air and water to induce oxygen and water molecules to be ionized and dissociated, and heat, electromagnetic waves and ultrasonic waves are released. The released heat is not only beneficial to rapidly increasing the temperature of the silicon ink acid slurry and promoting the hydrolysis and polymerization of partial phosphate radicals to generate polyphosphoric acid, but also beneficial to the dissolution of graphite powder and the release of silicon in the diatomite powder. Meanwhile, under the action of microwave, phosphoric acid can penetrate into mineral lattices contained in the diatomite, so that the dissolution of the diatomite is promoted. The high-energy electron beam reacts with oxygen, water molecules and hydrogen ions to generate oxygen radicals, hydroxyl radicals and hydrogen radicals. Oxygen and hydroxyl radicals can rapidly oxidize graphite, inducing its conversion to graphene oxide. The silicon released from the diatomaceous earth reacts with hydrogen radicals to form polysilicic acid. Under the action of ultrasonic waves, polyphosphoric acid, polysilicic acid and graphene oxide are mutually fused and crosslinked to form mixed colloid. Mixing gamma-mercaptopropyl trimethoxy silane and graphene-phosphorus polysilicate mixed colloid, and cementing silicon atoms in the gamma-mercaptopropyl trimethoxy silane on polysilicic acid in a form of chemical bonds in the aging process to form the sulfydryl-graphene-loaded phosphorus polysilicate substance. In the curing process, heavy metals are firstly adsorbed on sulfydryl and graphene in the modes of complexation, electrostatic adsorption, chemical precipitation and the like. And then the heavy metal adsorbed on the sulfydryl and the graphene is gradually wrapped by the phosphorus polysilicate colloid. Meanwhile, the mixed colloid can be filled in the pores of the original solidified material, and the solidified body structure is strengthened through geological polymerization and hydration reaction, so that the strength, the corrosion resistance and the thawing resistance of the solidified body are improved.
Has the advantages that: the preparation method is simple, and the sources of the required raw materials are wide. The curing enhancer prepared by the invention is added into the traditional curing material, so that the leaching concentration of heavy metal in a cured body can be effectively reduced, and the uniaxial compressive strength, acid resistance and thawing resistance of the cured body can be effectively improved.
Drawings
FIG. 1 is a flow chart of the treatment method of the present invention.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
Graphite powder was purchased from Qingdao morning graphite Co., Ltd. and had a carbon content of 99.9% (code: LC).
Diatomaceous earth powder was purchased from Sendzein Dayurt diatomaceous Earth Ltd, Dongguan (model: SD30-04), and made of 91.34% SiO2、3.75％Al2O3、2.26％Fe2O3、1.04％CaO、0.53％MgO、0.47％K2O、0.38％Na2O and 0.23 percent of organic matter.
The phosphoric acid is an analytical pure standard, and the content is more than 99 percent.
The sulfuric acid is concentrated sulfuric acid with the mass fraction of 98.3%, and the sulfuric acid solution in the embodiment is obtained by diluting the concentrated sulfuric acid with a corresponding amount of water.
Example 1 Effect of graphite powder and diatomaceous Earth powder mass ratio on the Performance of the prepared hardening enhancer for reinforcing Cement curing Properties
Respectively weighing graphite powder and diatomite powder according to the mass ratio of the graphite powder to the diatomite powder of 0.5:10, 0.7:10, 0.9:10, 1:10, 2:10, 3:10, 3.1:10, 3.3:10 and 3.5:10, and mixing to obtain nine groups of graphite silicon powder. Measuring phosphoric acid and 2M sulfuric acid solution according to the volume ratio of 1:1, mixing, and uniformly stirring to obtain the sulfur-phosphorus mixed acid solution. And weighing the nine groups of graphite silicon powder and nine groups of sulfur and phosphorus mixed acid liquor according to the solid-to-liquid ratio of 1:1mg/mL, mixing and uniformly stirring to obtain nine groups of silicon ink mixed acid slurries. And (3) carrying out low-temperature plasma irradiation on the nine groups of silicon ink mixed acid pulp mixed slurry for 30 minutes to obtain nine groups of graphene-polysilicon-phosphorus mixed colloids, wherein the irradiation action voltage of the low-temperature plasma is 20KV, and the action atmosphere of the low-temperature plasma is oxygen. Respectively weighing gamma-mercaptopropyl trimethoxy silane and graphene-polysilicon mixed colloid according to the volume ratio of 1:10, mixing, uniformly stirring, aging for 6 hours, drying and grinding to obtain nine groups of curing enhancers.
Heavy metal contaminated soil: the heavy metal contaminated soil sample is collected from soil in the area near a certain abandoned electroplating plant area in Jiangsu. And (3) after sampling the soil, placing the soil in a shade place for air drying for two weeks, grinding the soil sample, and sieving the ground soil sample by a 100-mesh sieve for later use. In the polluted soil, the mercury content is 202.04mg/kg, the cadmium content is 338.62mg/kg, and the arsenic content is 357.82 mg/kg.
Preparing a heavy metal contaminated soil strengthening solidification body: nine groups of heavy metal contaminated soil, nine groups of curing reinforcers prepared by the method and nine groups of cement are respectively weighed according to the mass ratio of 1:0.02:0.98 and are respectively mixed to obtain nine groups of solid mixtures, wherein the cement adopts the standard cement specified in the 'concrete admixture' GB8076-2008 appendix A. Respectively adding water into the nine groups of solid mixtures according to the solid-liquid ratio of 1:0.45mg/mL, fully stirring to form slurry with fluidity, pouring the slurry into a toughened mold with the size of 20mm multiplied by 20mm, compacting and forming on a vibration table, sealing the mold by using a polyethylene film, curing for 1 day under standard curing conditions (the temperature is 20 +/-2 ℃, and the relative humidity standard is more than 95%), demolding, and continuously curing for 28 days under the same conditions to obtain nine groups of heavy metal contaminated soil reinforced solidified bodies.
And (3) detecting the uniaxial compressive strength: the measurement of the compressive strength of the cured body is carried out according to the Standard "Cement mortar Strength test method (ISO method)" (GB/T17671) -1999.
Solid body weight metal leaching test and leaching concentration detection: the solidified heavy metal leaching test and the leaching concentration detection are carried out according to the acetic acid buffer solution method of the solid waste leaching toxicity leaching method (HJ/T300-2007).
The test results of this example are shown in Table 1.
TABLE 1 influence of the mass ratio of graphite powder to diatomaceous earth powder on the performance of the prepared hardening enhancer for strengthening cement hardening body
As can be seen from the results in table 1, when the mass ratio of the graphite powder to the diatomite powder is less than 1:10 (as shown in table 1, when the mass ratio of the graphite powder to the diatomite powder is 0.9:10, 0.7:10, 0.5:10 and lower values not listed in table 1), the graphene yield is reduced, polyphosphoric acid, polysilicic acid and graphene oxide are fused with each other, the crosslinking effect is poor, the mixed colloid which can be filled into the pores of the original cured material is reduced, the leaching concentration of heavy metals is significantly increased as the mass ratio of the graphite powder to the diatomite powder is reduced, and the uniaxial compressive strength of the cured body is significantly reduced as the mass ratio of the graphite powder to the diatomite powder is reduced; when the mass ratio of the graphite powder to the diatomite powder is 1-3: 10 (as shown in table 1, when the mass ratio of the graphite powder to the diatomite powder is 1:10, 2:10, or 3: 10), a proper amount of graphite powder is obtained, and the oxygen radical and the hydroxyl radical can rapidly oxidize graphite to generate graphene oxide. Under the action of ultrasonic waves, polyphosphoric acid, polysilicic acid and graphene oxide are mutually fused and crosslinked to form mixed colloid. In the curing process, heavy metals are firstly adsorbed on sulfydryl and graphene in the modes of complexation, electrostatic adsorption, chemical precipitation and the like. Meanwhile, the mixed colloid can be filled in the pores of the original solidified material, and the solidified body structure is strengthened through geological polymerization and hydration reaction, so that the strength, the corrosion resistance and the thawing resistance of the solidified body are improved. Finally, with the increase of the mass ratio of the graphite powder to the diatomite powder, the leaching concentration of the heavy metal is gradually reduced, and the uniaxial compressive strength of the solidified body is gradually increased; when the mass ratio of the graphite powder to the diatomite powder is greater than 3:10 (as shown in table 1, when the mass ratio of the graphite powder to the diatomite powder is 3.1:10, 3.3:10, 3.5:10 and higher values not listed in table 1), the graphite powder is excessive, the graphene generation amount is excessive, polyphosphoric acid, polysilicic acid and graphene oxide are mutually fused, the crosslinking effect is poor, the mixed colloid which can be filled into the pores of the original curing material is reduced, the heavy metal leaching concentration is gradually increased along with further increase of the mass ratio of the graphite powder to the diatomite powder, and the uniaxial compressive strength of the cured body is gradually reduced. Therefore, in summary, the benefit and the cost are combined, and when the mass ratio of the graphite powder to the diatomite powder is 1-3: 10, the prepared solidification enhancer is most beneficial to strengthening the cement solidified body.
Example 2 Effect of solid-liquid ratio of graphite-silicon powder and Sulfur-phosphorus acid mixture on the Properties of hardening enhancer for reinforcing Cement curing Properties
Respectively weighing the graphite powder and the diatomite powder according to the mass ratio of the graphite powder to the diatomite powder of 3:10, and mixing to obtain the graphite silicon powder. Measuring phosphoric acid and 4M sulfuric acid solution according to the volume ratio of 1.5:1, mixing, and uniformly stirring to obtain the sulfur-phosphorus mixed acid solution. Respectively weighing graphite silicon powder and sulfur-phosphorus mixed acid liquor according to the solid-liquid ratio of 1:0.5mg/mL, 1:0.7mg/mL, 1:0.9mg/mL, 1:1mg/mL, 1:1.5mg/mL, 1:2mg/mL, 1:2.1mg/mL, 1:2.3mg/mL and 1:2.5mg/mL, mixing, and uniformly stirring to obtain nine groups of silicon ink mixed acid slurries. And (3) carrying out low-temperature plasma irradiation on the nine groups of silicon ink mixed acid pulps for 45 minutes to obtain nine groups of graphene-polysilicon-phosphorus mixed colloids, wherein the irradiation action voltage of the low-temperature plasma is 60KV, and the action atmosphere of the low-temperature plasma is oxygen. Respectively weighing gamma-mercaptopropyl trimethoxy silane and graphene poly-silicon-phosphorus mixed colloid according to the volume ratio of 1.5:10, mixing, uniformly stirring, aging for 9 hours, drying and grinding to obtain nine groups of curing enhancers.
The preparation of the heavy metal contaminated soil, the preparation of the heavy metal contaminated soil strengthened solidified body, the detection of the uniaxial compressive strength, the metal leaching test of the solidified body weight and the detection of the leaching concentration are the same as those in example 1. The test results of this example are shown in Table 2.
TABLE 2 influence of solid-liquid ratio of graphite silicon powder and sulfur-phosphorus mixed acid liquid on performance of hardening enhancer for reinforcing cement solidification body prepared by the solid-liquid ratio
From the results in table 2, it can be seen that when the solid-to-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid solution is greater than 1:1 (as shown in table 2, when the solid-to-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid solution is 1:0.9, 1:0.7, 1:0.5 and larger values not listed in table 2), the sulfur-phosphorus mixed acid solution is less, the silicon dissolution amount in the diatomite is reduced, the generation amounts of polyphosphoric acid and polysilicic acid are correspondingly reduced, polyphosphoric acid, polysilicic acid and graphene oxide are mutually fused and have poorer crosslinking effects, the generation amount of mixed colloid is reduced, the mixed colloid which can be filled into the pores of the original cured material is reduced, and finally, the heavy metal leaching concentration is significantly increased and the uniaxial compressive strength of the cured body is significantly reduced with the increase of the solid-to-liquid ratio; when the solid-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid solution is equal to 1: 1-2 (as shown in table 2, when the solid-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid solution is 1:1, 1:1.5 and 1: 2), a proper amount of the sulfur-phosphorus mixed acid solution is obtained, polyphosphoric acid and polysilicic acid are subjected to crosslinking, polyphosphoric acid, polysilicic acid and graphene oxide are fully fused and crosslinked, a sufficient amount of mixed colloid is formed, and the mixed colloid which can be filled in the pores of the original curing material is sufficient. Finally, with the reduction of the solid-to-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid liquid, the leaching concentration of the heavy metal is gradually reduced, and the uniaxial compressive strength of the solidified body is gradually increased; when the solid-to-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid solution is less than 1:2 (as shown in table 2, when the solid-to-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid solution is 1:2.1, 1:2.3, 1:2.5 and smaller values not listed in table 2), the sulfur-phosphorus mixed acid solution is excessive, and excessive hydrogen ions react with the high-energy electron beam to generate excessive hydrogen radicals. Excessive hydrogen free radicals and hydrogen ions are easily combined with hydroxyl free radicals and oxygen free radicals, so that the yield of graphene oxide is reduced, and the generated reinforcer has excessive residual hydrogen ions, so that the hydration reaction in the curing process is not facilitated, the solid-liquid ratio of the graphite silicon powder and the sulfur-phosphorus mixed acid liquid is further reduced, the leaching concentration of heavy metals is remarkably increased, and the uniaxial compressive strength of a cured body is remarkably reduced. Therefore, in summary, the benefit and the cost are combined, and when the solid-to-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid liquid is equal to 1: 1-2, the prepared solidification strengthening agent is most beneficial to strengthening the cement solidified body.
Example 3 Effect of Low temperature plasma action Voltage on the Performance of the prepared hardening agent to strengthen the Cement Cure Property
Respectively weighing the graphite powder and the diatomite powder according to the mass ratio of the graphite powder to the diatomite powder of 3:10, and mixing to obtain the graphite silicon powder. Measuring phosphoric acid and 6M sulfuric acid solution according to the volume ratio of 2:1, mixing, and uniformly stirring to obtain the sulfur-phosphorus mixed acid solution. Respectively weighing graphite silicon powder and sulfur-phosphorus mixed acid liquor according to the solid-to-liquid ratio of 1:2mg/mL, mixing and uniformly stirring to obtain silicon ink mixed acid slurry. And respectively carrying out low-temperature plasma irradiation on the nine groups of silicon ink mixed acid pulps for 60 minutes to obtain the graphene-polysilicon-phosphorus mixed colloid, wherein the low-temperature plasma irradiation action voltages of the nine groups of silicon ink mixed acid pulps are respectively 5KV, 10KV, 15KV, 20KV, 60KV, 100KV, 105KV, 110KV and 115KV, and the action atmosphere of the low-temperature plasma is oxygen. Respectively weighing nine groups of gamma-mercaptopropyl trimethoxy silane and nine groups of graphene poly-silicon-phosphorus mixed colloids according to the volume ratio of 2:10, mixing, uniformly stirring, aging for 12 hours, drying and grinding to obtain nine groups of curing reinforcers.
The preparation of the heavy metal contaminated soil, the preparation of the heavy metal contaminated soil strengthened solidified body, the detection of the uniaxial compressive strength, the metal leaching test of the solidified body weight and the detection of the leaching concentration are the same as those in example 1. The test results of this example are shown in Table 3.
TABLE 3 Effect of Low temperature plasma applied Voltage on the Performance of the prepared hardening enhancer for strengthening Cement hardeners
As can be seen from the results in table 3, when the low-temperature plasma applied voltage is lower than 20KV (as shown in table 3, when the low-temperature plasma applied voltage is 15KV, 10KV, and 5KV, and smaller values not listed in table 3), the energy of the high-energy electrons released by the high-voltage electrode is lower, the efficiency of the high-energy electrons impacting air and water is lower, the generation amount of graphene oxide and polyphosphoric acid is reduced, and finally, the heavy metal leaching concentration is significantly increased and the uniaxial compressive strength of the cured body is significantly reduced with the reduction of the low-temperature plasma applied voltage; when the low-temperature plasma action voltage is equal to 20-100 KV (as shown in table 3, the low-temperature plasma action voltage is 20KV, 60KV, and 100 KV), the high-energy electrons released from the high-voltage electrode impact air and water to induce ionization and dissociation of oxygen and water molecules and release heat, electromagnetic waves, and ultrasonic waves. The released heat is not only beneficial to rapidly increasing the temperature of the silicon ink acid slurry and promoting the hydrolysis and polymerization of partial phosphate radicals to generate polyphosphoric acid, but also beneficial to the dissolution of graphite powder and the release of silicon in the diatomite powder. Meanwhile, under the action of microwave, phosphoric acid can penetrate into mineral lattices contained in the diatomite, so that the dissolution of the diatomite is promoted. The high-energy electron beam reacts with oxygen, water molecules and hydrogen ions to generate oxygen radicals, hydroxyl radicals and hydrogen radicals. Oxygen and hydroxyl radicals can rapidly oxidize graphite, inducing its conversion to graphene oxide. Finally, with the increase of the action voltage of the low-temperature plasma, the leaching concentration of the heavy metal is gradually reduced, and the uniaxial compressive strength of the solidified body is gradually increased; when the low-temperature plasma acting voltage is higher than 100KV (as shown in table 3, when the low-temperature plasma acting voltage is 105KV, 110KV and 115KV and larger values not listed in table 3), the low-temperature plasma acting voltage is too high, and when high-energy electrons collide with air and water, excessive oxygen radicals and hydroxyl radicals are generated, so that the mixed colloid is inactivated, and finally, the leaching concentration of heavy metal does not decrease and inversely increases, and the uniaxial compressive strength of the solidified body does not increase and inversely decreases with further increase of the low-temperature plasma acting voltage. Therefore, in summary, the benefit and the cost are combined, and when the low-temperature plasma action voltage is equal to 20-100 KV, the prepared curing enhancer is most beneficial to strengthening the cement cured body.
Comparative example 1 comparison of uniaxial compressive strength and heavy metal leaching performance of reinforced cured body and cement cured body
The preparation of the solidification enhancer of the invention: respectively weighing the graphite powder and the diatomite powder according to the mass ratio of the graphite powder to the diatomite powder of 3:10, and mixing to obtain the graphite silicon powder. Measuring phosphoric acid and 6M sulfuric acid solution according to the volume ratio of 2:1, mixing, and uniformly stirring to obtain the sulfur-phosphorus mixed acid solution. Respectively weighing graphite silicon powder and sulfur-phosphorus mixed acid liquor according to the solid-to-liquid ratio of 1:2mg/mL, mixing and uniformly stirring to obtain silicon ink mixed acid slurry. And (3) irradiating the mixed acid pulp by using low-temperature plasma for 60 minutes to obtain the graphene-poly-silicon-phosphorus mixed colloid, wherein the irradiation action voltage of the low-temperature plasma is 100KV respectively, and the action atmosphere of the low-temperature plasma is oxygen. Respectively weighing gamma-mercaptopropyl trimethoxy silane and graphene poly-silicon-phosphorus mixed colloid according to the volume ratio of 2:10, mixing, uniformly stirring, aging for 12 hours, drying and grinding to obtain the curing enhancer.
The preparation of the heavy metal contaminated soil was the same as in example 1.
Preparing a cement solidified body of the heavy metal contaminated soil: respectively weighing heavy metal contaminated soil and cement according to the mass ratio of 1:1, and mixing to obtain a solid mixture, wherein the cement adopts standard cement specified in the concrete admixture GB8076-2008 appendix A. Adding water into the solid mixture according to the solid-liquid ratio of 1:0.45mg/mL, fully stirring to form slurry with fluidity, pouring the slurry into a toughened mold with the thickness of 20mm multiplied by 20mm, compacting and molding on a vibration table, sealing the mold by using a polyethylene film, curing for 1 day under standard curing conditions (the temperature is 20 +/-2 ℃, and the relative humidity standard is more than 95%), demolding, and continuously curing for 28 days under the same conditions to obtain the heavy metal contaminated soil cement solidified body.
The preparation of the heavy metal contaminated soil strengthening solidified body, the detection of uniaxial compressive strength, the metal leaching test of the solidified body weight and the detection of leaching concentration are the same as those in example 1. The test results of this comparative example are shown in Table 4.
TABLE 4 comparison of uniaxial compressive strength and heavy metal leaching performance of the reinforced solidification body and the cement solidification body
From the results in table 4, it is understood that the uniaxial compressive strength of the reinforced cured body is significantly higher than that of the cement cured body, and the leaching concentration of heavy metals of the reinforced cured body is significantly lower than that of the cement cured body.
Comparative example 2 comparison of compressive strength and corrosion resistance coefficient of reinforced solidified body and cement solidified body and total spalling mass performance of unit surface area of test piece
The curing enhancer of the present invention was prepared in the same manner as in comparative example 1.
Preparation of heavy metal contaminated soil and strengthening solidification body of heavy metal contaminated soil were the same as in example 1.
The preparation of the cement solidified body for heavy metal contaminated soil was the same as in comparative example 1.
Sulfate erosion resistance test and compressive strength corrosion resistance coefficient (%) calculation: the sulfate erosion resistance test and the compressive strength and corrosion resistance coefficient (%) calculation are carried out according to the standard of test methods for long-term performance and durability of ordinary concrete (GBT 50082-2009).
And (3) performing freeze-thaw resistance test and calculating the mass loss rate of the test piece: the freezing and thawing resistance test and the test piece quality loss rate calculation are both carried out according to the test method standard for the long-term performance and the durability performance of common concrete (GBT 50082-2009).
The test results of this comparative example are shown in Table 5.
TABLE 5 comparison of compressive strength, corrosion resistance and specimen mass loss rate of the reinforced solidification body and the cement solidification body
The results in Table 5 show that the compressive strength and corrosion resistance coefficient of the reinforced solidified body are obviously higher than those of the cement solidified body, and the mass loss rate of the test piece of the reinforced solidified body is obviously lower than that of the cement solidified body.
Claims (10)
1. The preparation method of the solidification enhancer is characterized by comprising the following steps:
1) mixing graphite powder and diatomite powder to obtain graphite silicon powder;
2) mixing phosphoric acid and sulfuric acid solution, and uniformly stirring to obtain a sulfur-phosphorus mixed acid solution;
3) mixing the graphite silicon powder and the sulfur-phosphorus mixed acid liquor, and uniformly stirring to obtain silicon-ink mixed acid slurry;
4) performing low-temperature plasma irradiation on the silicon ink mixed acid pulp for 30-60 minutes to obtain a graphene-poly-silicon-phosphorus mixed colloid;
5) and mixing the gamma-mercaptopropyl trimethoxy silane and the graphene-polysilicon mixed colloid, uniformly stirring, aging for 6-12 hours, drying, and grinding to obtain the curing enhancer.
2. The method for preparing the solidification enhancer according to claim 1, wherein the mass ratio of the graphite powder to the diatomaceous earth powder in the step 1) is 1-3: 10.
3. The method for preparing a solidification enhancer according to claim 1, wherein the volume ratio of the phosphoric acid solution to the sulfuric acid solution in the step 2) is 1-2: 1.
4. The method for preparing the solidification enhancer according to claim 1, wherein the solid-to-liquid ratio of the graphite silicon powder to the sulfur-phosphorus mixed acid liquid in the step 3) is 1: 1-2 mg/mL.
5. The method for preparing a hardening enhancer according to claim 1, wherein the low-temperature plasma irradiation applied voltage in the step 4) is 20 to 100KV, and the applied atmosphere of the low-temperature plasma is oxygen.
6. The method for preparing the solidification enhancer according to claim 1, wherein the volume ratio of the gamma-mercaptopropyl-trimethoxysilane to the graphene-polysilicophosphorus mixed colloid in the step 5) is 1-2: 10.
7. The solidification enhancer prepared by the preparation method of claim 1 to 6.
8. Use of the solidification enhancer of claim 7 for the treatment of contaminated soil.
9. The use according to claim 8, wherein the contaminated soil is a heavy metal contaminated soil.
10. The use according to claim 9, wherein the heavy metal is one or more of mercury, cadmium or arsenic.
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| CN111729640A (en) * | 2020-06-24 | 2020-10-02 | 常熟理工学院 | Preparation method of modified vermiculite adsorbent |
| CN112029508A (en) * | 2020-09-10 | 2020-12-04 | 常熟理工学院 | Thallium and arsenic contaminated soil remediation agent and preparation method and application thereof |
| CN112125586A (en) * | 2020-09-23 | 2020-12-25 | 常熟理工学院 | Preparation method and application of sulfhydryl modified graphene oxide nanosheet/geopolymer composite material |
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| CN111729640B (en) * | 2020-06-24 | 2022-11-25 | 常熟理工学院 | Preparation method of modified vermiculite adsorbent |
| CN112029508A (en) * | 2020-09-10 | 2020-12-04 | 常熟理工学院 | Thallium and arsenic contaminated soil remediation agent and preparation method and application thereof |
| CN112125586A (en) * | 2020-09-23 | 2020-12-25 | 常熟理工学院 | Preparation method and application of sulfhydryl modified graphene oxide nanosheet/geopolymer composite material |
| CN112125586B (en) * | 2020-09-23 | 2022-07-29 | 常熟理工学院 | Preparation method and application of sulfydryl modified graphene oxide nanosheet/geopolymer composite material |
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