Heavy metal curing material as well as preparation method and application thereof

Abstract

The invention discloses a heavy metal curing material and a preparation method and application thereof, and the preparation method comprises the following steps: S1, in the presence of an organic solvent, mixing zinc nitrate and an organosilicon compound, carrying out solid-liquid separation, and drying to obtain a precursor; s2, mixing the precursor and bottom mud, adding water to prepare bottom mud slurry, stirring, filtering and drying to obtain a composite base material, and calcining the composite base material to obtain a porous material; s3, mixing the porous material with the magnetic nanoparticles, performing solid-liquid separation to obtain a magnetic composite material, and mixing the magnetic composite material with an iron salt solution for reaction to obtain the heavy metal curing material. The curing material prepared by the method is high and stable in adsorption rate and high in compressive strength.

Description

Technical Field

[0001] This invention relates to the field of heavy metal contaminated water treatment, specifically to a recyclable and regenerable magnetically loaded geopolymer heavy metal solidification material, its preparation method, and its application. Background Technology

[0002] With the acceleration of industrialization and urbanization, heavy metal pollution has become a global environmental problem, especially in the treatment of industrial wastewater, polluted sediment, and electronic waste, where efficient and low-cost heavy metal solidification technologies are urgently needed. Traditional solidification materials (such as cement-based materials and biochar) generally suffer from limited adsorption capacity, poor regeneration performance, high cost, and insufficient environmental compatibility. Conventional materials have low adsorption efficiency for high-valence heavy metals, making it difficult to meet the needs of high-concentration pollution scenarios. Moreover, most materials cannot effectively desorb after adsorption, leading to an increased risk of secondary pollution. Furthermore, their reliance on high-purity raw materials (such as nano-iron oxide and activated carbon) hinders large-scale application. In addition, some materials may release harmful substances during the solidification process, exacerbating ecological risks.

[0003] In existing technologies, while Fe3O4@SiO2 composite materials reported in the literature possess magnetic separation capabilities, they do not integrate waste resources (such as sediment) to reduce costs. However, the carrier obtained solely from sediment has a small specific surface area, resulting in a low loading capacity for magnetic nanoparticles, which in turn leads to a low adsorption rate for heavy metals. Furthermore, its mechanical strength is insufficient to meet application requirements, resulting in unsatisfactory adsorption effects of heavy metal solidification materials. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of low adsorption efficiency and insufficient mechanical strength of adsorption materials in the prior art, thereby providing a method for preparing heavy metal solidification materials.

[0005] According to an embodiment of the present invention, in a first aspect, a method for preparing a heavy metal curing material is provided, comprising the following steps:

[0006] S1, in the presence of an organic solvent, zinc nitrate and an organosilicon compound are mixed, separated into solid and liquid phases, and dried to obtain the precursor;

[0007] S2, after mixing the precursor and sediment, water is added to prepare sediment slurry, which is then stirred, filtered and dried to obtain a composite substrate. The composite substrate is then calcined to obtain a porous material.

[0008] S3, mix porous materials and magnetic nanoparticles, separate the solid and liquid to obtain a magnetic composite material, mix the magnetic composite material with an iron salt solution and react to obtain a heavy metal solidification material.

[0009] In one embodiment of the present invention, the bottom sediment includes river and lake bottom sediment, which, on a dry basis, includes an organic matter content of 5wt% to 15wt%, a silica content of 40wt% to 60wt%, an alumina content of 10wt% to 20wt%, a calcium oxide content of 10wt% to 20wt%, and an iron oxide content of 10wt% to 15wt%.

[0010] The water content of the river and lake bottom sediment slurry is 70%-90%, the water content of the river and lake bottom sediment is less than or equal to 40wt%, and the particle size of the river and lake bottom sediment is less than or equal to 150μm.

[0011] In one embodiment of the present invention, in step S1, the organosilicon compound includes at least one of tetramethyl silicate, tetraethyl orthosilicate, and methyltrimethoxysilane.

[0012] Organic solvents include at least one of anhydrous ethanol, anhydrous methanol, and anhydrous diethyl ether;

[0013] The ratio of zinc nitrate to organosilicon compounds is 1:0.5-2;

[0014] The step of mixing zinc nitrate and organosilicon compounds includes adding the zinc nitrate solution dropwise to the organosilicon compound solution;

[0015] The solid-liquid separation step in step S1 includes separation by centrifugation.

[0016] In one embodiment of the present invention, in step S2, the mass ratio of the precursor to the bottom mud is 1:0.5-3.

[0017] The method for preparing the porous material includes mixing sediment and precursor, adding water to prepare sediment slurry, stirring for 2-8 hours, filtering and drying to obtain composite substrate, and calcining the obtained composite substrate at 450-750℃ for 1.5-4 hours in an oxidizing atmosphere to obtain porous material.

[0018] The stirring is done in a gradient manner, specifically, stirring at 200-400 rpm for 30-60 minutes, then at 600-800 rpm for 60-120 minutes, and finally at 50-100 rpm for 2-6 hours of oscillation and maturation.

[0019] The calcination is carried out in stages. Specifically, the temperature is first raised to 300-400℃ at 3-5℃ / min and held for 0.5-1 hour, and then raised to 550-750℃ at 8-12℃ / min and calcined for 1-3 hours.

[0020] In one embodiment of the present invention, in step S3, the magnetic nanoparticles include Fe3O4@SiO2 particles, and the mass ratio of the porous material to the magnetic nanoparticles is 1:0.25-0.5.

[0021] Step S3, which involves mixing porous materials and magnetic nanoparticles, includes dispersing the porous materials in anhydrous ethanol, adding magnetic nanoparticles, ultrasonically loading them while simultaneously using an external magnetic field to assist sedimentation, separating them, and drying them to obtain a magnetic composite material. The magnetic composite material is then mixed with an iron salt solution to react and obtain a heavy metal curing material.

[0022] In one embodiment of the present invention, in step S3, the iron salt includes one of ferric chloride and ferric sulfate, and the pH value of the iron salt solution is 2-4.

[0023] The ratio of magnetic composite material to iron salt solution is 1g:10-15mL, and the concentration of iron salt is 0.5-1.5mol / L;

[0024] The reaction time of the magnetic composite material with the iron salt solution is 2 hours. During the reaction, an external magnetic field strengthening step is also included, with a magnetic field strength of 0.5-1.5T.

[0025] The magnetic field strength during the external magnetic field-assisted settling process is 0.5-1.5T;

[0026] In step S3, the drying temperature of the magnetic composite material is 40-60℃, and the drying time is 1-2 hours.

[0027] According to an embodiment of the present invention, in a second aspect, a heavy metal curing material is provided, wherein the heavy metal curing material is prepared by any of the above-described methods for preparing heavy metal curing materials.

[0028] According to an embodiment of the present invention, in a third aspect, the application of the above-described heavy metal solidification material in solidifying heavy metals in wastewater is provided.

[0029] As one embodiment of the present invention, the method for solidifying heavy metals in wastewater includes the following steps:

[0030] Heavy metal solidification material is added to wastewater to adsorb heavy metals. The amount of heavy metal solidification material added is 0.5-8.0 g / L based on the volume of wastewater.

[0031] As one embodiment of the present invention, the method for solidifying heavy metals in wastewater further includes a step of desorbing and regenerating the heavy metal solidification material. Specifically, the method includes mixing the heavy metal solidification material adsorbed with heavy metals with an acid solution, wherein the concentration of the acid solution is 0.1-2 mol / L.

[0032] The technical solution of this invention has the following advantages:

[0033] 1. The present invention provides a method for preparing a heavy metal curing material, comprising the following steps: S1, in the presence of an organic solvent, zinc nitrate and an organosilicon compound are mixed, solid-liquid separation is performed, and the mixture is dried to obtain a precursor; S2, the precursor and sediment are mixed and water is added to prepare a sediment slurry, which is then stirred, filtered, and dried to obtain a composite substrate, and the composite substrate is calcined to obtain a porous material; S3, the porous material and magnetic nanoparticles are mixed, solid-liquid separation is performed to obtain a magnetic composite material, and the magnetic composite material is mixed and reacted with an iron salt solution to obtain a heavy metal curing material.

[0034] This invention uses waste river and lake sediment as a carrier, organosilicon compounds as the silicon source, and zinc nitrate as the zinc source to construct a ternary composite framework (ZnO-SiO2-sediment minerals). ZnO fills the gaps in the SiO2 network, improving the compressive strength of the carrier. Furthermore, the gases (NO2, O2) decomposed during the high-temperature calcination of zinc nitrate can form micro- and nano-pores, optimizing the pore structure and increasing the specific surface area, thereby increasing the loading of magnetic nanoparticles and thus increasing the adsorption capacity. Simultaneously, the calcined ZnO spontaneously forms a hydroxylated layer (Zn-OH) on its surface in aqueous solution, readily coordinating with metals. Iron salts undergo hydrolysis in acidic aqueous solution, generating FeOOH particles rich in uncoordinated Fe-O- and Fe-OH groups. Zn-OH and Fe-OH can undergo dehydration to form Zn-O-Fe bonds, enhancing the coordination ability with heavy metal ions. Combined with the semiconductor properties of ZnO, this accelerates the reduction of heavy metal ion valence states, thereby increasing the adsorption capacity.

[0035] 2. The present invention provides a method for preparing a heavy metal solidification material. In the preparation of the porous material, gradient stirring and segmented calcination are used to ensure that the porosity and mechanical strength of the porous carrier can meet the requirements for use. The magnetic nanoparticles are loaded and reinforced with FeCl3 solution to ensure its adsorption effect on heavy metals. Attached Figure Description

[0036] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the process flow for the preparation method of heavy metal curing material provided in Embodiment 1 of the present invention.

[0038] Figure 2This is a flow chart of the adsorption-desorption cycle of the heavy metal curing material provided in Embodiment 1 of the present invention. Detailed Implementation

[0039] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0040] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0041] Example 1

[0042] This embodiment provides a method for preparing a heavy metal curing material, the specific steps and parameters of which are as follows:

[0043] (1) Solution preparation: Dissolve 20g of tetramethyl silicate in 200mL of anhydrous ethanol and stir magnetically for 30min to form mixed solution A;

[0044] (2) Precursor synthesis: 105 mL of 0.5 mol / L zinc nitrate solution was added dropwise to mixed solution A at a rate of 2 mL / min. After the addition was complete, the mixture was stirred at 400 rpm for 3 h. After centrifugation, the mixture was washed three times alternately with ethanol and water. The mixture was then dried under vacuum at 60 °C for 12 h to obtain white powder B, which is the precursor.

[0045] (3) Preparation of composite substrate: River and lake bottom mud (moisture content 20%) was crushed and passed through a 100-mesh sieve. The dry basis content of each component of the river and lake bottom mud was: organic matter 10wt%, SiO2 60wt%, Al2O3 10wt%, CaO 10wt%, Fe2O3 10wt%. The precursor and the crushed and sieved bottom mud were mixed at a mass ratio of 1:3, and then water was added to prepare a bottom mud slurry with a moisture content of 70wt%. The bottom mud slurry was first stirred at 350rpm for 45min, then stirred at 700rpm for 60min, and finally oscillated and matured at 80rpm for 4h. After filtration, it was poured into a spherical mold and dried in an oven at 80℃ to obtain spherical material C, which is the composite substrate.

[0046] (4) Calcination to create pores: Under an oxygen atmosphere, the temperature is first raised to 350℃ at 4℃ / min and held for 1h, then raised to 650℃ at 10℃ / min and calcined for 1.5h to obtain porous carrier D;

[0047] (5) Magnetic loading: The porous carrier D was dispersed in anhydrous ethanol at a mass ratio of 1:15. 50% of the mass of the porous carrier D was added to Fe3O4@SiO2 (50nm particle size) core-shell structured particles and ultrasonically treated for 2h. At the same time, a 0.5T magnetic field was applied to assist sedimentation. After separation, the magnetic composite material E was obtained by drying at 60℃ for 1h.

[0048] (6) Iron salt fixation: The magnetic composite material E was reacted in a FeCl3 solution with pH=3 for 2 hours. During the reaction, a 0.5T magnetic field was applied to enhance the fixation effect. After filtration, the solid was vacuum dried to obtain the cured material F.

[0049] Example 2

[0050] Reference Figure 1 This embodiment provides a method for preparing a heavy metal curing material, the specific steps and parameters of which are as follows:

[0051] (1) Solution preparation: Dissolve 20g of tetraethyl orthosilicate in 200mL of anhydrous methanol and stir magnetically for 30min to form mixed solution A;

[0052] (2) Precursor synthesis: 210 mL of 0.5 mol / L zinc nitrate solution was added dropwise to mixed solution A at a rate of 2 mL / min. After the addition was complete, the mixture was stirred at 400 rpm for 4 h. After centrifugation, the mixture was washed three times alternately with ethanol and water. The mixture was then dried under vacuum at 60 °C for 12 h to obtain white powder B, which is the precursor.

[0053] (3) Preparation of composite substrate: River and lake bottom mud (moisture content 30%) was crushed and passed through a 100-mesh sieve. The dry basis content of each component of the bottom mud was: organic matter 5wt%, SiO2 60wt%, Al2O3 15wt%, CaO 10wt%, Fe2O3 10wt%. The precursor and the crushed and sieved bottom mud were mixed at a mass ratio of 1:2, and then water was added to prepare a bottom mud slurry with a moisture content of 80wt%. The bottom mud slurry was first stirred at 350rpm for 45min, then stirred at 700rpm for 90min, and finally oscillated and matured at 80rpm for 5h. After filtration, it was poured into a spherical mold and dried in an oven at 80℃ to obtain spherical material C, which is the composite substrate.

[0054] (4) Calcination to create pores: Under an oxygen atmosphere, the temperature is first raised to 350℃ at 4℃ / min and held for 1h, then raised to 550℃ at 10℃ / min and calcined for 3h to obtain porous carrier D;

[0055] (5) Magnetic loading: Porous carrier D is dispersed in anhydrous ethanol at a mass ratio of 1:12. Fe3O4@SiO2 (50nm particle size) core-shell structured particles, which account for 30% of the mass of porous carrier D, are added and ultrasonically treated for 2 hours. Simultaneously, a 1T magnetic field is applied to assist sedimentation. After separation, the magnetic composite material E is obtained by drying at 60℃ for 1 hour.

[0056] (6) Iron salt fixation: The magnetic composite material E was reacted in a FeCl3 solution with pH=3 for 2 hours. During the reaction, a 1T magnetic field was applied to enhance the fixation effect. After filtration, the solid was vacuum dried to obtain the cured material F.

[0057] Example 3

[0058] This embodiment provides a method for preparing a heavy metal curing material, the specific steps and parameters of which are as follows:

[0059] (1) Solution preparation: Dissolve 20g of methyltrimethoxysilane in 200mL of anhydrous diethyl ether and stir magnetically for 30min to form mixed solution A;

[0060] (2) Precursor synthesis: 420 mL of 0.5 mol / L zinc nitrate solution was added dropwise to mixed solution A at a rate of 2 mL / min. After the addition was complete, the mixture was stirred at 400 rpm for 4 h. After centrifugation, the mixture was washed three times alternately with ethanol and water. The mixture was then dried under vacuum at 60 °C for 12 h to obtain white powder B, which is the precursor.

[0061] (3) Preparation of composite substrate: River and lake bottom mud (moisture content 40%) was crushed and passed through a 100-mesh sieve. The dry basis content of each component of the bottom mud was: organic matter 10wt%, SiO2 50wt%, Al2O3 15wt%, CaO 15wt%, Fe2O3 10wt%. The precursor and the crushed and sieved bottom mud were mixed at a mass ratio of 1:0.5, and then water was added to prepare a bottom mud slurry with a moisture content of 90%. The bottom mud slurry was first stirred at 350 rpm for 45 min, then stirred at 700 rpm for 90 min, and finally oscillated and matured at 80 rpm for 4 h. After filtration, it was poured into a spherical mold and dried in an oven at 80°C to obtain spherical material C, which is the composite substrate.

[0062] (4) Calcination to create pores: Under an oxygen atmosphere, the temperature is first raised to 350℃ at 4℃ / min and held for 0.5h, and then calcined at 750℃ at 10℃ / min for 1h to obtain porous carrier D;

[0063] (5) Magnetic loading: Porous carrier D was dispersed in anhydrous ethanol at a mass ratio of 1:18. 25% of Fe3O4@SiO2 (20nm particle size) core-shell structured particles of porous carrier D were added and ultrasonically treated for 2h. Then, 20% of Fe3O4@SiO2 (80nm particle size) core-shell structured particles of porous carrier D were added and ultrasonically treated for 2h. At the same time, a 1.5T magnetic field was applied to assist sedimentation. After separation, the magnetic composite material E was obtained by drying at 40℃ for 2h.

[0064] (6) Iron salt fixation: The magnetic composite material E was reacted in a FeSO4 solution with pH=4 for 2 hours. During the reaction, a magnetic field of 1.5T was applied to enhance the fixation effect. After filtration, the solid was vacuum dried to obtain the cured material F.

[0065] Example 4

[0066] This embodiment provides a method for preparing a heavy metal curing material, the specific steps and parameters of which are as follows:

[0067] (1) Solution preparation: Dissolve 20g of tetramethyl silicate in 200mL of anhydrous ethanol and stir magnetically for 30min to form mixed solution A;

[0068] (2) Precursor synthesis: 315 mL of 0.5 mol / L zinc nitrate solution was added dropwise to mixed solution A at a rate of 2 mL / min. After the addition was complete, the mixture was stirred at 400 rpm for 4 h. After centrifugation, the mixture was washed three times alternately with ethanol and water. The mixture was then dried under vacuum at 60 °C for 12 h to obtain white powder B, which is the precursor.

[0069] (3) Preparation of composite substrate: River and lake bottom mud (moisture content 30%) was crushed and passed through a 100-mesh sieve. The dry basis content of each component of the bottom mud was: organic matter 15wt%, SiO2 40wt%, Al2O3 20wt%, CaO 15wt%, Fe2O3 10wt%. The precursor and the crushed and sieved bottom mud were mixed at a mass ratio of 1:3, and then water was added to prepare a mud slurry with a moisture content of 80wt%. The mud slurry was first stirred at 350rpm for 45min, then stirred at 700rpm for 90min, and finally oscillated and matured at 80rpm for 4h. After filtration, it was poured into a spherical mold and dried in an oven at 80℃ to obtain spherical material C, which is the composite substrate.

[0070] (4) Calcination to create pores: Under an oxygen atmosphere, the temperature is first raised to 350℃ at 4℃ / min and held for 1h, then raised to 450℃ at 10℃ / min and calcined for 3h to obtain porous carrier D;

[0071] (5) Magnetic loading: The porous carrier D was dispersed in anhydrous ethanol at a mass ratio of 1:15. Fe3O4@SiO2 (50nm particle size) core-shell structured particles, which account for 30% of the mass of the porous carrier D, were added and ultrasonically treated for 2 hours. At the same time, a 1T magnetic field was applied to assist sedimentation. After separation, the magnetic composite material E was obtained by drying at 60℃ for 1 hour.

[0072] (6) Iron salt fixation: The magnetic composite material E was reacted in a FeSO4 solution with pH=2 for 2 hours. During the reaction, a 1T magnetic field was applied to enhance the fixation effect. After filtration, the solid was vacuum dried to obtain the cured material F.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing a heavy metal curing material, the specific steps and parameters of which are as follows:

[0075] (1) Preparation of composite substrate: River and lake bottom mud (moisture content 30%) was crushed and passed through a 100-mesh sieve. The dry basis content of each component of the bottom mud was: organic matter 5wt%, SiO2 60wt%, Al2O3 15wt%, CaO 10wt%, Fe2O3 10wt%. The precursor and the crushed and sieved bottom mud were mixed at a mass ratio of 1:2, and then water was added to prepare a bottom mud slurry with a moisture content of 80wt%. The bottom mud slurry was first stirred at 350rpm for 45min, then stirred at 700rpm for 90min, and finally oscillated and matured at 80rpm for 4h. After filtration, it was poured into a spherical mold and dried in an oven at 80℃ to obtain spherical material C, which is the composite substrate.

[0076] (2) Calcination to create pores: Under an oxygen atmosphere, the temperature is first raised to 350℃ at 4℃ / min and held for 1h, then raised to 550℃ at 10℃ / min and calcined for 3h to obtain carrier D;

[0077] (3) Magnetic loading: The carrier D was dispersed in anhydrous ethanol, with a mass ratio of porous carrier D to anhydrous ethanol of 1:15. 30% of the mass of porous carrier D was added to Fe3O4@SiO2 (50nm particle size) core-shell structured particles, which were ultrasonically treated for 2h. At the same time, a 1T magnetic field was applied to assist sedimentation. After separation, the magnetic composite material E was obtained by drying at 60℃ for 1h.

[0078] (4) Iron salt fixation: The magnetic composite material E was reacted in a FeCl3 solution with pH=3 for 2 hours. During the reaction, a 1T magnetic field was applied to enhance the fixation effect. After filtration, the solid was vacuum dried to obtain the cured material F.

[0079] Comparative Example 2

[0080] This comparative example provides a method for preparing a heavy metal curing material, the specific steps and parameters of which are as follows:

[0081] (1) Solution preparation: Dissolve 20g of tetramethyl silicate in 200mL of anhydrous ethanol and stir magnetically for 30min to form mixed solution A;

[0082] (2) Precursor synthesis: 210 mL of 0.5 mol / L copper nitrate solution was added dropwise to mixed solution A at a rate of 2 mL / min. After the addition was complete, the mixture was stirred at 400 rpm for 4 h. After centrifugation, the mixture was washed three times alternately with ethanol and water. The mixture was then dried under vacuum at 60 °C for 12 h to obtain powder B, which is the precursor.

[0083] (3) Preparation of composite substrate: River and lake bottom mud (moisture content 30%) was crushed and passed through a 100-mesh sieve. The dry basis content of each component of the bottom mud was: organic matter 5wt%, SiO2 60wt%, Al2O3 15wt%, CaO 10wt%, Fe2O3 10wt%. The precursor and the crushed and sieved mud were mixed at a mass ratio of 1:2, and then water was added to prepare a mud slurry with a moisture content of 80%. The mud slurry was first stirred at 350 rpm for 45 min, then stirred at 700 rpm for 90 min, and finally oscillated and matured at 80 rpm for 4 h. After filtration, it was poured into a spherical mold and dried in an oven at 80°C to obtain spherical material C, which is the composite substrate.

[0084] (4) Calcination to create pores: Under an oxygen atmosphere, the temperature is first raised to 350℃ at 4℃ / min and held for 1h, then raised to 550℃ at 10℃ / min and calcined for 3h to obtain porous carrier D;

[0085] (5) Magnetic loading: Porous carrier D is dispersed in anhydrous ethanol at a mass ratio of 1:15. 30% of the mass of porous carrier D is added to Fe3O4@SiO2 (50nm particle size) core-shell structured particles, which are ultrasonically treated for 2h. At the same time, a 1T magnetic field is applied to assist sedimentation. After separation, the magnetic composite material E is obtained by drying at 60℃ for 1h.

[0086] (6) Iron salt fixation: The magnetic composite material E was reacted in a FeCl3 solution with pH=3 for 2 hours. During the reaction, a 1T magnetic field was applied to enhance the fixation effect. After filtration, the solid was vacuum dried to obtain the cured material F.

[0087] Application Examples 1-6

[0088] See Figure 2 This application example provides a method for solidifying heavy metals in wastewater, with the specific steps and parameters as follows:

[0089] (1) Heavy metal wastewater adsorption: The prepared heavy metal solidification material was placed in lead-containing wastewater, where Pb in the lead-containing wastewater... 2+ The initial concentration was 50 mg / L, the pH value was 5.2, and the Pb in the wastewater was measured after 1 hour of adsorption.2+ Concentration, calculate the initial adsorption rate.

[0090] (2) Regeneration treatment: The adsorbed solidified material was dynamically desorbed with 1.2 mol / L HCl (flow rate 3 BV / h) for 1.5 h, and then regenerated by neutralization treatment with 0.04 mol / L NaOH.

[0091] The adsorption was repeated using the above method, and the regeneration process was repeated 5 times. The adsorption rate of the 5 regeneration processes was then measured.

[0092] The heavy metal curing materials in Application Examples 1-6 are the heavy metal curing materials prepared in Examples 1-4 and Comparative Examples 1-2 of the present invention, respectively.

[0093] The specific surface area of ​​the heavy metal curing materials prepared in Examples 1-4 and Comparative Examples 1-2 was determined.

[0094] (GB / T19587-2017) and compressive strength (GB / T 50081-2019); determination of lead in water (GB / T7475-1987); calculation of the adsorption rate of each heavy metal solidification material for heavy metals in wastewater, adsorption rate = (Pb before adsorption) 2+ Concentration - Pb after adsorption 2+ (concentration) / Pb before adsorption 2+ The concentration and test results are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] As shown in Table 1, compared to Comparative Example 1, the precursor obtained without zinc nitrate was mixed with the mud during the preparation of porous materials, making it impossible to construct a ternary composite framework (ZnO-SiO2-mud minerals). Comparative Example 2 used copper nitrate to construct a ternary composite framework (CuO-SiO2-mud minerals). In this embodiment of the invention, tetramethyl silicate was used as the silicon source for the organosilicon compound, and zinc nitrate was used as the zinc source to construct a ternary composite framework (ZnO-SiO2-mud minerals). The specific surface area of ​​the resulting heavy metal curing agent was significantly higher than that of Comparative Example 1, but almost the same as that of Comparative Example 2. This indicates that the gas generated during the high-temperature calcination of hydrochloride can form micro-nano channels, optimize the pore structure, and increase the specific surface area. The compressive strength was significantly higher than that of Comparative Example 1 and Comparative Example 2, indicating that the ternary composite framework (ZnO-SiO2-mud minerals) has superior strength performance.

[0099] The initial adsorption rate of heavy metals in wastewater reached 99.2%, and the adsorption rate after 5 regenerations reached 97.8%, which is significantly better than Comparative Example 1 and Comparative Example 2. This is because the ZnO formed after calcination of the porous support spontaneously forms a hydroxylation layer (Zn-OH) on the surface of the aqueous solution, which easily undergoes coordination reaction with metals. Iron salts undergo hydrolysis reaction in acidic aqueous solution to generate FeOOH particles with uncoordinated Fe-O- and Fe-OH groups on the surface. Zn-OH and Fe-OH can undergo dehydration reaction to generate Zn-O-Fe bonds, which enhances the coordination ability of heavy metal ions. Combined with the semiconductor properties of ZnO, it can accelerate the reduction of the valence state of heavy metal ions, thereby improving the adsorption capacity.

[0100] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a heavy metal curing material, characterized in that, Includes the following steps: S1, in the presence of an organic solvent, zinc nitrate and an organosilicon compound are mixed, separated into solid and liquid phases, and dried to obtain the precursor; S2, after mixing the precursor and sediment, water is added to prepare sediment slurry, which is then stirred, filtered and dried to obtain a composite substrate. The composite substrate is then calcined to obtain a porous material. S3, mix porous materials and magnetic nanoparticles, separate the solid and liquid to obtain a magnetic composite material, mix the magnetic composite material with an iron salt solution and react to obtain a heavy metal solidification material.

2. The method for preparing the heavy metal solidification material according to claim 1, characterized in that, The sediment includes river and lake sediment, which, on a dry basis, comprises 5 wt%–15 wt% organic matter, 40 wt%–60 wt% silica, 10 wt%–20 wt% alumina, 10 wt%–20 wt% calcium oxide, and 10 wt%–15 wt% ferric oxide; and / or, The water content of the river and lake bottom sediment slurry is 70%-90%, the water content of the river and lake bottom sediment is less than or equal to 40wt%, and the particle size of the river and lake bottom sediment is less than or equal to 150μm.

3. The method for preparing a heavy metal solidification material according to claim 1, characterized in that, In step S1, the organosilicon compound includes at least one selected from tetramethyl silicate, tetraethyl orthosilicate, and methyltrimethoxysilane; and / or, Organic solvents include at least one of anhydrous ethanol, anhydrous methanol, and anhydrous diethyl ether; and / or, The mass ratio of zinc nitrate to organosilicon compound is 1:0.5-2; and / or, The steps of mixing zinc nitrate and organosilicon compounds include adding a zinc nitrate solution dropwise to an organosilicon compound solution; and / or, The solid-liquid separation step in step S1 includes separation by centrifugation.

4. The method for preparing a heavy metal solidification material according to claim 1, characterized in that, In step S2, the mass ratio of the precursor to the sediment is 1:0.5-3; and / or, The method for preparing the porous material includes mixing sediment and a precursor, adding water to prepare a sediment slurry, stirring for 2-8 hours, filtering and drying to obtain a composite substrate, and calcining the obtained composite substrate at 450-750℃ for 1.5-4 hours in an oxidizing atmosphere to obtain the porous material; and / or, The stirring is done in a gradient manner, specifically, stirring at 200-400 rpm for 30-60 minutes, then at 600-800 rpm for 60-120 minutes, and finally at 50-100 rpm for 2-6 hours of oscillation and maturation. The calcination is carried out in stages. Specifically, the temperature is first raised to 300-400℃ at 3-5℃ / min and held for 0.5-1 hour, and then raised to 550-750℃ at 8-12℃ / min and calcined for 1-3 hours.

5. The method for preparing a heavy metal solidification material according to claim 1, characterized in that, In step S3, the magnetic nanoparticles include Fe3O4@SiO2 particles, and the mass ratio of the porous material to the magnetic nanoparticles is 1:0.25-0.5; and / or, Step S3, which involves mixing porous materials and magnetic nanoparticles, includes dispersing the porous materials in anhydrous ethanol, adding magnetic nanoparticles, ultrasonically loading them while simultaneously using an external magnetic field to assist sedimentation, separating them, and drying them to obtain a magnetic composite material. The magnetic composite material is then mixed with an iron salt solution to react and obtain a heavy metal curing material.

6. A method for preparing a heavy metal solidification material according to claim 1 or 5, characterized in that, In step S3, the iron salt includes either ferric chloride or ferric sulfate, and the pH of the iron salt solution is 2-4; and / or, The ratio of magnetic composite material to iron salt solution is 1g:10-15mL, and the concentration of iron salt is 0.5-1.5mol / L; and / or, The magnetic composite material was mixed with an iron salt solution and reacted for 2 hours. The reaction process also included a step of strengthening the reaction with an external magnetic field, the strength of which was 0.5-1.5 T; and / or, The magnetic field strength during the externally applied magnetic field-assisted settling process is 0.5-1.5 T; and / or, In step S3, the drying temperature of the magnetic composite material is 40-60℃, and the drying time is 1-2 hours.

7. A heavy metal curing material, characterized in that, The heavy metal curing material is prepared by the preparation method of the heavy metal curing material according to any one of claims 1-6.

8. The application of the heavy metal solidification material according to claim 7 in solidifying heavy metals in wastewater.

9. The application according to claim 8, characterized in that, The method for solidifying heavy metals in wastewater includes the following steps: Heavy metal solidification material is added to wastewater to adsorb heavy metals. The amount of heavy metal solidification material added is 0.5-8.0 g / L based on the volume of wastewater.

10. The application according to claim 9, characterized in that, The method for solidifying heavy metals in wastewater also includes a step of desorbing and regenerating the heavy metal solidification material. Specifically, the method involves mixing the heavy metal solidification material with adsorbed heavy metals with an acid solution, wherein the concentration of the acid solution is 0.1-2 mol / L.

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