A multi-layer structure material for heavy metal ion adsorption and a preparation method thereof

Abstract

The application discloses a kind of multilayer structure material for heavy metal ion adsorption and preparation method thereof.Based on red mud and water-jet loom sludge as basic material, form tablet thin layer after pre-treatment and high-temperature sintering form porous thin layer aggregate, in the process of cooling, auxiliary structure stable gradient pore diameter spinning fiber is applied voltage, and load metal oxide nanoparticles, form with sustained, safe and high adsorption performance Heavy metal ion adsorption multilayer structure material, for the simultaneous removal of As, Pb, Hg, Cr, Cu multiple heavy metals or metalloid pollutants in coal mine area soil.The application uses two kinds of solid waste to treat and reuse, so that it forms porous thin layer aggregate with porous structure, and then loads spinning fiber and metal oxide adsorption material to form multilayer structure material, which strengthens heavy metal adsorption performance, and can realize the simultaneous removal of As, Pb, Hg, Cr, Cu multiple heavy metals or metalloid in coal mine area soil or groundwater.

Description

Technical Field

[0001] This invention belongs to the field of adsorption structural materials technology, specifically referring to a multilayer structural material for the adsorption of heavy metal ions and its preparation method. Background Technology

[0002] Coal mining areas, especially solid waste dumps, often contain various heavy metal pollutants, such as As, Cu, Hg, and Cr. These heavy metals / metalloids can easily leach into groundwater through the soil with rainwater, posing a potential pollution risk to both aquatic and soil environments. This hinders the restoration of the mining area's ecological environment and harms human production and daily life. Existing heavy metal treatment methods often suffer from the limitations of durable and non-recyclable adsorbent materials, and cannot simultaneously adsorb and remove multiple heavy metals, which are urgent problems that need to be addressed.

[0003] Red mud is a type of tailings slag, produced in enormous quantities annually and difficult to dispose of. Current research has found that high-temperature calcination or acidification of red mud can physicochemically modify it, producing products with cementing, adsorption, and catalytic properties, showing promising application prospects. Water-jet loom sludge is produced in large quantities, possessing a certain degree of viscosity and relatively abundant organic matter, and can be used for soil remediation after certain treatments. However, how to combine red mud and water-jet loom sludge to form a porous, multi-layered adsorbent material with a large surface area, and then perform surface treatment to obtain a material with various heavy metal adsorption properties and good recyclability, while simultaneously achieving resource utilization of solid waste and pollutant removal, has not yet been reported. Summary of the Invention

[0004] The purpose of this invention is to provide a multilayer structure material for heavy metal ion adsorption and its preparation method, which can be used to adsorb and treat various heavy metals in soil or groundwater in coal mining areas, while realizing the resource utilization of solid waste and the removal of pollutants.

[0005] To achieve the above objectives, this invention provides a multilayer structured material for heavy metal ion adsorption. Using red mud and water-jet loom sludge as base materials, the material is formed into a compressed thin layer, pretreated, and then sintered at high temperature to form a porous thin-layer aggregate. During the cooling process, a voltage is applied to supplement the structure with structurally stable gradient-pore-size spinning fibers, which are then loaded with metal oxide nanoparticles. This forms a multilayer structured material with continuous, safe, and high adsorption performance for heavy metal ion adsorption, used for the simultaneous removal of multiple heavy metals or metalloid pollutants such as As, Pb, Hg, Cr, and Cu from soil or groundwater in coal mining areas.

[0006] A method for preparing a multilayer structured material for heavy metal ion adsorption includes the following steps:

[0007] Step 1: Red mud and water jet loom sludge are mixed in different proportions, and sodium carboxymethyl cellulose is added to enhance coagulation. The mixture is pressed into a plate-shaped thin layer with a thickness of 0.5 cm, then sintered at high temperature and cooled to shrink into porous thin-layer aggregate. The surface of the porous thin-layer aggregate is pretreated to break the dense oxide layer on the surface.

[0008] Step 2: When the porous thin-layer aggregate from Step 1 is cooled to 200℃~300℃, a spinning solution is sprayed onto it in a low-voltage electric field of 10~15kV and an oxygen-deficient environment to fully load the components in the solution onto the porous aggregate, thus preparing a gradient pore size fiber membrane. Simultaneously, carbonization is performed to form a spinning-loaded porous thin-layer structure material. Then, the temperature is lowered to room temperature. This is the loading of the second and third layers of adsorbent material.

[0009] Step 3: Immerse the spun-loaded porous thin-layer structure material from Step 2 in a metal compound solution and ultrasonically disperse it to ensure that the solute fully adheres to the spun-loaded porous thin-layer structure material. This is the loading of the fourth layer of adsorbent material.

[0010] Step 4: Depending on the oxide preparation conditions, add an acid or alkali solution to the solution in Step 3 to adjust its pH. After heat treatment, wash with deionized water and ethanol alternately and dry to constant weight. Depending on the type of metal oxide obtained, choose whether to perform subsequent calcination treatment to finally obtain a multilayer structure material for heavy metal ion adsorption.

[0011] As a further aspect of the present invention: the ratio of red mud and water-jet loom sludge in step one is 1.5:1 to 3:1. They are thoroughly mixed and 0.5% to 2.0% sodium carboxymethyl cellulose by mass is added to enhance coagulation. The mixture is pressed into a plate-shaped thin layer with a thickness of 0.5 cm. The dense oxide layer on the surface is removed by low-temperature plasma or acid-base etching. Then, it is sintered into a porous thin-layer aggregate at a sintering temperature of 400 to 600 °C.

[0012] As a further embodiment of the present invention: in step two, the spinning solution uses polyvinylpyrrolidone or a mixture of polyacrylonitrile or polyvinylpyrrolidone as the spinning polymer, formamide as the solvent, and ferric chloride hexahydrate with a concentration of 1% to 3% is added to enhance the toughness of the spun fibers. The concentration of the spinning polymer is 5% to 10%, and the spraying is maintained for 1 to 2 hours.

[0013] In step two, a gradient pore size fiber membrane is prepared by electrospinning on the surface of a porous thin-layer aggregate using multi-nozzle spinning. The outer layer forms large-pore fibers of 200-500 nm, which are used for rapid adsorption and retention of suspended particles. The inner layer forms small-pore fibers of less than 100 nm, which are used to provide fine adsorption sites.

[0014] In step two, a low-voltage electric field is applied while nitrogen gas is introduced, creating a dual electrospinning and carbonization environment of low-voltage electric field and oxygen deficiency.

[0015] As a further aspect of the present invention: the metal compound solution in step three includes, but is not limited to, manganese chloride, aluminum chloride, magnesium chloride, cerium nitrate solution or a mixture thereof, which, after treatment, can form a metal oxide with heavy metal adsorption properties on the surface of the structural material; wherein, the ratio of the mass of the spinning on the structural material to the mass of the above solution is between 1:1 and 1.5:1.

[0016] As a further aspect of the present invention: the heat treatment in step four is carried out under closed conditions, the material is immersed after the solution is fully mixed, the heat treatment temperature is 150~200℃, and the treatment time is 2~3h; and the final multilayer structure material can be loaded with one or more metal oxides.

[0017] As a further aspect of the present invention: the multilayer structural material is resistant to the initial pH range of wastewater between 3 and 10, and the initial heavy metal ion concentration is between 0 and 2 mg / L.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention utilizes two types of solid waste for treatment and reuse, forming a porous thin-layer material with a porous structure for heavy metal adsorption. This material is then loaded with spun fibers and metal oxide adsorbents to form a multilayer structured material for heavy metal ion adsorption, enabling the simultaneous removal of multiple heavy metals or metalloids such as As, Pb, Hg, Cr, and Cu from soil. Furthermore, the multilayer structured material formed by this invention possesses certain structural stability and recyclability, allowing for repeated heavy metal adsorption and demonstrating good economic applicability. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of a multilayer structure material for heavy metal ion adsorption according to the present invention.

[0020] Figure 2 This is a SEM image of the surface of the multilayer structure material after adsorbing metal oxides (loaded by the fourth layer of adsorbent material).

[0021] Figure 3 The removal rate of heavy metal pollutants in Example 1.

[0022] Figure 4 In Example 1, (a), (b), and (c) represent the adsorption efficiencies of the multilayer material for As, Hg, and Pb in a mixed heavy metal contaminated solution after four adsorption-desorption cycles.

[0023] Figure 5 The removal rate of heavy metal pollutants in Example 2.

[0024] Figure 6In Example 2, (a), (b), and (c) represent the adsorption efficiencies of the multilayer material for Hg, Cr, and Pb in a mixed heavy metal contaminated solution after four adsorption-desorption cycles. Detailed Implementation

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] A multilayer structured material for heavy metal ion adsorption is based on red mud and water-jet loom sludge. After forming a compressed thin layer, it is pretreated and sintered at high temperature to form a porous thin-layer aggregate. During the cooling process, a voltage is applied to assist in the spinning of structurally stable gradient pore size fibers, which are then loaded with metal oxide nanoparticles to form a multilayer structured material for heavy metal ion adsorption with continuous, safe and high adsorption performance. This material can be used to simultaneously remove multiple heavy metals or metalloid pollutants such as As, Pb, Hg, Cr and Cu from soil or groundwater in coal mining areas.

[0027] like Figure 1 As shown, the preparation method of the multilayer structure material for heavy metal ion adsorption includes the following steps:

[0028] Step 1: Red mud and water jet loom sludge are mixed in different proportions, and sodium carboxymethyl cellulose is added to enhance coagulation. The mixture is pressed into a plate-shaped thin layer with a thickness of 0.5 cm, then sintered at high temperature and cooled to shrink into porous thin-layer aggregate. The surface of the porous thin-layer aggregate is pretreated to break the dense oxide layer on the surface.

[0029] Step 2: When the porous thin-layer aggregate from Step 1 is cooled to 200℃~300℃, a spinning solution is sprayed onto it in a low-voltage electric field of 10~15kV and an oxygen-deficient environment to fully load the components in the solution onto the porous aggregate, thus preparing a gradient pore size fiber membrane. Simultaneously, carbonization is performed to form a spinning-loaded porous thin-layer structure material. Then, the temperature is lowered to room temperature. This is the loading of the second and third layers of adsorbent material.

[0030] Step 3: Immerse the spun-loaded porous thin-layer structure material from Step 2 in a metal compound solution and ultrasonically disperse it to ensure that the solute fully adheres to the spun-loaded porous thin-layer structure material. This is the loading of the fourth layer of adsorbent material.

[0031] Step 4: Depending on the oxide preparation conditions, add an acid or alkali solution to the solution in Step 3 to adjust its pH. After heat treatment, wash with deionized water and ethanol alternately and dry to constant weight. Depending on the type of metal oxide obtained, choose whether to perform subsequent calcination treatment to finally obtain a multilayer structure material for heavy metal ion adsorption.

[0032] In step one, the ratio of red mud to water-jet loom sludge is 1.5:1 to 3:1. The mixture is thoroughly mixed and 0.5%-2.0% sodium carboxymethyl cellulose is added to enhance coagulation. The mixture is then pressed into a plate-shaped thin layer with a thickness of 0.5 cm. The dense oxide layer on the surface is removed by low-temperature plasma or acid-base etching. Subsequently, it is sintered into a porous thin-layer aggregate at a sintering temperature of 400-600℃.

[0033] In step two, the spinning solution uses polyvinylpyrrolidone or a mixture of polyacrylonitrile or polyvinylpyrrolidone as the spinning polymer, formamide as the solvent, and ferric chloride hexahydrate at a concentration of 1% to 3% to enhance the toughness of the spun fibers. The concentration of the spinning polymer is 5% to 10%, and the spraying is maintained for 1 to 2 hours.

[0034] In step two, a gradient pore size fiber membrane is prepared by electrospinning on the surface of a porous thin-layer aggregate using multi-nozzle spinning. The outer layer forms large-pore fibers of 200-500 nm, which are used for rapid adsorption and retention of suspended particles. The inner layer forms small-pore fibers of less than 100 nm, which are used to provide fine adsorption sites.

[0035] In step two, a low-voltage electric field is applied while nitrogen gas is introduced, creating a dual electrospinning and carbonization environment of low-voltage electric field and oxygen deficiency.

[0036] The metal compound solution in step three includes, but is not limited to, manganese chloride, aluminum chloride, magnesium chloride, cerium nitrate solution or a mixture thereof. After treatment, it can form a metal oxide with heavy metal adsorption properties on the surface of the structural material. The ratio of the mass of the spinning on the structural material to the mass of the above solution is between 1:1 and 1.5:1.

[0037] The heat treatment in step four is carried out under closed conditions. After the solution is fully mixed, the material is immersed in it. The heat treatment temperature is 150~200℃ and the treatment time is 2~3h. The resulting multilayer structure material can be loaded with one or more metal oxides.

[0038] The multilayer structure material used for heavy metal ion adsorption is resistant to the initial pH range of wastewater between 3 and 10, and the initial heavy metal ion concentration between 0 and 2 mg / L.

[0039] Example 1:

[0040] This embodiment discloses a multilayer structural material for heavy metal ion adsorption and its preparation method. The aggregate material consists of red mud and water-jet loom sludge, with sodium carboxymethyl cellulose added to enhance coagulation. After sintering to form a porous thin-layer aggregate, spinning fibers are loaded onto the spinning solution, followed by the loading of cerium oxide adsorbent material, thus forming a multilayer structural material that is lightweight, renewable, and capable of adsorbing multiple metal ions. The preparation process is as follows: Figure 1 As shown, the preparation method is as follows.

[0041] First, red mud and water-jet loom sludge were mixed in a ratio of 1.5:1, with the water-jet loom sludge having a moisture content of 50%. After the two substances were thoroughly mixed, 2% sodium carboxymethyl cellulose was added, and the mixture was coagulated and pressed into a plate-shaped thin layer with a thickness of 0.5 cm. After high-temperature sintering at 600℃ for 2 hours, it was allowed to cool naturally, shrinking into a porous thin-layer aggregate. The dense oxide layer on the surface was then removed using low-temperature plasma technology.

[0042] When the aforementioned porous thin-layer aggregate is cooled to 300℃, a spinning solution is prepared by spraying a mixture of polyacrylonitrile, polyvinylpyrrolidone, and ferric chloride in a 1:1:2 ratio, using formamide as the solvent, with a spinning polymer concentration of 10%. Under nitrogen protection, a voltage of 15kV is applied to the spray nozzle, and the solution is slowly sprayed for 1 hour to allow the components in the solution to be fully loaded onto the porous thin-layer aggregate, forming inner layer fibers with a pore size of less than 100nm. The nozzle is then changed, and spraying is continued for another hour to form outer layer fibers with a pore size of approximately 200nm.

[0043] Prepare a 20% cerium nitrate solution, immerse the above-mentioned spinning-loaded porous thin-layer structure material in the solution, and ultrasonically disperse it for half an hour to allow cerium ions to fully adhere to the spinning-loaded porous thin-layer structure material. The ratio of the mass of the spun yarn to the mass of the solution is 1:1.

[0044] A certain amount of ammonia solution was added to the ultrasonicated solution, and after magnetic stirring for 1 hour, the pH was adjusted to neutral with nitric acid. The solution was then heat-treated at 150°C under sealed conditions for 2 hours. After cooling, the solution was filtered, washed alternately with deionized water and ethanol, and dried at 80°C to constant weight to obtain a multilayer structured material for heavy metal ion adsorption. Its surface characteristics are as follows: Figure 2 As shown.

[0045] Weigh 5g of the multilayer structure material prepared above, prepare a mixed heavy metal solution of Hg, As, Cr, Pb and Cu with an initial concentration of 2mg / L, adjust the pH value to 3, place the multilayer structure material in 100mL of mixed heavy metal solution, and shake at 100 rpm to allow the heavy metals to be adsorbed by the multilayer structure material.

[0046] After 1 hour of adsorption, the concentration of the remaining heavy metal pollutants in the solution was measured using inductively coupled plasma mass spectrometry (ICP-MS).

[0047] The concentration of the remaining heavy metal pollutants in the above solution was measured and its removal rate was calculated.

[0048] Using the above method, this embodiment utilizes a multilayer structure material to stably and continuously adsorb and remove heavy metal ions such as As, Hg, Pb, Cu, and Cr, achieving a removal efficiency of over 96%. The results are as follows... Figure 3As shown, even after four adsorption-desorption cycles, it still maintains a heavy metal pollutant removal rate of over 75%, as indicated by the results. Figure 4 As shown, the prepared multilayer structure material exhibits stable adsorption properties.

[0049] Example 2:

[0050] Red mud and water-jet loom sludge were mixed in a 3:1 ratio, with the water-jet loom sludge having a moisture content of 80%. After the two substances were thoroughly mixed, 0.5% sodium carboxymethyl cellulose was added, and the mixture was coagulated and pressed into a 0.5 cm thick plate-like thin layer. After high-temperature sintering at 400℃ for 2 hours, it was naturally cooled to shrink into a porous thin-layer aggregate. The aggregate was then soaked successively in a 1 mol / L hydrochloric acid solution and a strong sodium oxide solution for 0.5 hours to break down the dense oxide layer on the surface.

[0051] When the porous aggregate is cooled to 200°C, a spinning solution is prepared by spraying a mixture of polyvinylpyrrolidone and ferric chloride in a 1:2 ratio, using dimethylformamide as the solvent, with a spinning polymer concentration of 5%. Under nitrogen protection, a voltage of 10 kV is applied to the nozzle, and the solution is slowly sprayed for 1 hour to allow the components in the solution to be fully loaded onto the porous aggregate, forming inner layer fibers with a pore size of less than 100 nm. The nozzle is then changed, and the solution is sprayed for another hour to form outer layer fibers with a pore size of approximately 500 nm, thus forming a spun-loaded porous thin-layer structure material.

[0052] A 10% magnesium chloride solution was prepared, and the above-mentioned spun-supported porous thin-layer structure material was immersed in the solution. An equal volume and concentration of sodium carbonate solution was then added dropwise, and the mixture was ultrasonically dispersed at 80°C for 2 hours. This ensured that the ions were fully attached to the spun-supported porous thin-layer structure material, with a spun fiber mass to solution mass ratio of 1.5:1.

[0053] After cooling and filtration, the material was washed alternately with deionized water and ethanol, dried to constant weight at 80°C, and calcined in a muffle furnace at 400°C for 1 hour to obtain a multilayer structured material for heavy metal ion adsorption.

[0054] Weigh 5g of the multilayer structure material prepared above for heavy metal ion adsorption, prepare a mixed heavy metal solution of Hg, As, Cr, Pb and Cu with an initial concentration of 2mg / L, adjust the pH of the solution to 10, place the multilayer structure material in 100mL of the mixed heavy metal solution, and shake at 100 rpm to allow the heavy metals to be adsorbed by the multilayer structure material.

[0055] After 1 hour of adsorption, the concentration of the remaining heavy metal pollutants in the solution was measured using inductively coupled plasma mass spectrometry.

[0056] The concentration of the remaining heavy metal pollutants in the above solution was measured and its removal rate was calculated.

[0057] Using the above method, this embodiment utilizes a multilayer structure material to stably and continuously adsorb and remove heavy metal ions such as As, Hg, Cr, and Cu, achieving a removal efficiency of over 96%. The results are as follows... Figure 5 As shown, even after four adsorption-desorption cycles, it still maintains a heavy metal pollutant removal rate of over 72%, as indicated by the results. Figure 6 As shown, the prepared multilayer structure material exhibits stable adsorption properties.

[0058] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a multilayer structured material for heavy metal ion adsorption, characterized by, The method comprises the following steps: Step one, red mud and water jet loom sludge are mixed in different proportions, and carboxymethyl cellulose sodium is added to strengthen coagulation, and then pressed into a plate-shaped thin layer with a thickness of 0.5 cm, and then the surface of the plate-shaped thin layer is pretreated to break the dense oxide layer on the surface, and then high-temperature sintering and cooling are carried out, and shrinkage into a porous thin layer aggregate is carried out; Step two, when the porous thin layer aggregate in step one is cooled to 200-300 DEG C, a spinning solution is sprayed in a low-voltage electric field and an oxygen-deficient environment, so that the components in the solution are fully loaded on the porous thin layer aggregate, a gradient pore size fiber membrane is prepared, and carbonization is simultaneously formed to form a spinning-loaded porous thin layer structure material, and then cooled to room temperature, which is the loading of the second and third layers of adsorbent materials; Step three, the spinning-loaded porous thin layer structure material in step two is immersed in a metal compound solution, and ultrasonic dispersion is carried out to make the solute fully adhere to the spinning-loaded porous thin layer structure material, which is the loading of the fourth layer of adsorbent material; Step four, whether to add an acid solution or an alkali solution to the solution in step three to adjust the pH value thereof is selected according to the preparation conditions of the oxide; after heat treatment, the material is washed with deionized water and ethanol alternately and then dried to constant weight, and whether to carry out subsequent calcination treatment is selected according to the type of the desired metal oxide, and finally a multi-layer structure material for heavy metal ion adsorption is obtained; The ratio of red mud and water jet loom sludge in step one is 1.5:1-3:1, and 0.5%-2.0% of carboxymethyl cellulose sodium by mass fraction is added to strengthen coagulation, and then pressed into a plate-shaped thin layer with a thickness of 0.5 cm, and then the surface dense oxide layer is broken by low-temperature plasma or acid-base etching, and then sintered into a porous thin layer aggregate, and the sintering temperature is 400-600 DEG C.

2. The method of claim 1, wherein the method is characterized by: The spinning solution in step two uses single polyvinylpyrrolidone or a mixed solution of polyvinylpyrrolidone and polyacrylonitrile as a spinning polymer, formyl dimethyl amine as a solvent, and 1%-3% of iron chloride hexahydrate is added to strengthen the toughness of the spinning fiber, and the spinning polymer concentration is 5%-10%, and the spraying is maintained for 1-2 h; In step two, a multi-nozzle spinning is used to electrospun a gradient pore size fiber membrane on the surface of the porous thin layer aggregate; wherein the outer layer forms a large pore size fiber of 200-500 nm for rapid adsorption and interception of suspended particles; and the inner layer forms a small pore size fiber of less than 100 nm for providing fine adsorption sites; In step two, nitrogen is introduced while applying a low-voltage electric field to form a low-voltage electric field and an oxygen-deficient double electrospinning and carbonization environment.

3. The method for preparing a multilayer structured material for heavy metal ion adsorption according to claim 1, characterized in that, The metal compound solution in step three includes but is not limited to manganese chloride, aluminum chloride, magnesium chloride, cerium nitrate solution or a mixed solution thereof, and after treatment, metal oxide nanoparticles with heavy metal adsorption performance can be formed on the surface of the multi-layer structure material; wherein the mass ratio of the spinning quality on the multi-layer structure material to the metal compound solution is 1:1-1.5:

1.

4. The method of claim 1, wherein the material is prepared by the steps of: The heat treatment in step four is under a closed condition, the solution is fully mixed and then the material is immersed, the heat treatment temperature is 150-200 DEG C, the treatment time is 2-3 h; and the finally formed multi-layer structure material can load one or more metal oxide nanoparticles.

5. The method of claim 1, wherein the multi-layered material for heavy metal ion adsorption is prepared by the steps of: The multi-layer structure material can resist the initial pH range of wastewater between 3 and 10 and the initial heavy metal ion concentration between 0 and 2 mg / L.

6. A multi-layered structured material for heavy metal ion adsorption prepared according to the method of any one of claims 1 to 5, characterized by, Based on red mud and water-jet loom sludge, a porous thin-layer aggregate is formed by tabletting, pretreatment, high-temperature sintering, application of voltage in the cooling process, gradient pore size spinning fibers with stable structure, and loading of metal oxide nanoparticles, thereby forming a heavy metal ion adsorption multi-layer structure material with continuous, safe and high adsorption performance for simultaneous removal of As, Pb, Hg, Cr, Cu and other heavy metal or metalloid pollutants in the soil or groundwater of a coal mine area.

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