Preparation method and application of cadmium and arsenic synchronous removal schulteite-based small ball which can be recycled

Abstract

The application provides a preparation method of a recyclable cadmium-arsenic synchronous removal schlenk mineral-based small ball, and belongs to the field of pollution control and remediation, and comprises the following steps: sodium alginate is added into water to obtain a sodium alginate aqueous solution, and corn starch is further added to obtain a sol; polyethylene nanoparticles are uniformly mixed with deionized water to obtain a medium; schlenk minerals are added into the medium to obtain a mixed solution, and a precipitate is obtained after centrifugation; the precipitate is uniformly mixed in the sol until a mixed sol is formed; the mixed sol is dropped into a FeCl2 solution drop by drop, and microspheres are prepared after crosslinking at room temperature, and the schlenk mineral-based small ball is obtained after drying. The small ball can be used for remediation of cadmium-arsenic contaminated soil. The preparation method is simple, the conditions are mild, and the operation is simple; the material only needs to be scattered into the soil, the resource utilization of waste is realized, and the small ball can be prepared in large quantities and popularized.

Description

Technical Field

[0001] This invention belongs to the field of pollution control and remediation, specifically relating to a method for preparing and applying recyclable Scheres mineral-based microspheres for simultaneous removal of cadmium and arsenic. Background Technology

[0002] Soil quality is crucial to food safety and even national security. Cadmium and arsenic are prevalent in the soils of rice-growing areas in China, and wastewater irrigation, organic fertilizer application, and pesticide use are the main causes of cadmium and arsenic pollution in paddy fields. Cadmium is a highly toxic heavy metal of global concern. Compared with other heavy metals, cadmium and arsenic have relatively strong migration capabilities in soil, easily accumulate in organisms, and enter the human body through the food chain, posing serious health risks. Therefore, finding scientifically effective methods to remediate cadmium and arsenic-contaminated paddy field soil is of paramount importance.

[0003] Currently, the ecological and health risks of heavy metals in soil remain primarily due to stabilization; the total amount of heavy metals in the soil has not decreased. If the soil environment changes after stabilization, the fixed heavy metals may be released again, posing a pollution risk. Existing regulations such as the "Trial Measures for the Management of Agricultural Land Soil Environment" and the "Standards for the Environmental Quality of Agricultural Land Soil" both base soil management on the total amount of pollutants in the soil. Reducing the total amount of heavy metals in polluted soil, improving soil quality, and ensuring the safety of agricultural products are effective strategies for mitigation and remediation (pollution reduction and purification). Therefore, research on removing the total amount of heavy metals in soil is one of the important research directions for mitigation and remediation of heavy metal pollution in soil.

[0004] Chinese Patent 202311531957.4 discloses the preparation of a floating hollow microsphere material and its application in reducing cadmium in soil. This patent uses modified attapulgite mixed with polyvinyl alcohol, sodium alginate, sodium EDTA, and saponin, cross-linked to obtain a floating 3D-hollow microsphere material. This material is applied to moist soil for heavy metal adsorption. After irrigation, the material floats, and the floating microspheres are either directly recovered using a filter or collected and removed from the soil using a filter screen at the drainage outlet. While this patent effectively reduces heavy metals in soil, the floating 3D-hollow microsphere material has a low density. When applied to paddy fields, it floats directly on the water surface. This limits the adsorption efficiency as the spheres do not fully contact the solution, and also prevents them from making close contact with the soil for more efficient cadmium removal. Chinese Patent 202011509168.7 discloses a magnetic composite material for removing heavy metals from soil, its preparation, and its application. This material fully utilizes the superparamagnetism of Fe3O4, facilitating separation via magnetic separation, and can truly reduce the content of heavy metals. While the aforementioned patent can effectively remove heavy metals through enrichment and separation using a simple external magnetic field, the interaction between magnetic particles and the soil's electric field, as well as the redox interactions with pollutants in the soil, can affect soil physicochemical properties, enzyme activity, and greenhouse gas emissions. It can also influence the structure, function, and metabolism of soil microbial communities, thus impacting the entire soil ecosystem.

[0005] Cadmium and arsenic often coexist in contaminated soils, exhibiting different chemical behaviors, making simultaneous remediation challenging. Methods such as adsorption, chemical precipitation, electrochemical methods, ion exchange, membrane separation, and phytoremediation have been established and developed for removing cadmium and arsenic co-pollutants. Among these, adsorption can achieve total removal of cadmium and arsenic from soil. Schiele minerals, due to their unique mineral structure, have shown good potential for pollutant remediation. Existing research indicates that Schiele minerals have good adsorption performance for anionic arsenic but limited adsorption performance for cationic cadmium, thus requiring further modification of Schiele minerals to achieve synergistic remediation of cadmium and arsenic. Previous experience has shown that microspheres facilitate the recycling of remediation materials; therefore, this invention utilizes Schiele minerals to develop a recyclable, highly efficient, and environmentally friendly microsphere for the co-removal of cadmium and arsenic in paddy fields. Summary of the Invention

[0006] To address the shortcomings of existing technologies in terms of material functionality and application limitations, and to develop a simple and environmentally friendly cadmium pollution remediation material, this invention discloses a method for preparing and applying recyclable Schiff mineral-based microspheres for simultaneous cadmium and arsenic removal. The remediation material of this invention has a wide range of applications, suitable for both aquatic environments and flooded soils. The raw materials are readily available, environmentally friendly, and the preparation process is simple and mild, allowing for widespread application. The material is easy to use; simply scattering it into the environment is sufficient for its effectiveness. It is also easy to recycle and can be reused multiple times.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] This invention provides a method for preparing recyclable Schiff mineral-based microspheres for simultaneous removal of cadmium and arsenic, comprising the following steps:

[0009] (1) Add sodium alginate to water and heat in a water bath while stirring to dissolve it completely to obtain an aqueous solution of sodium alginate;

[0010] (2) Add corn starch to the solution described in step (1), heat in a water bath, stir until the solution becomes clear, cool to room temperature and set aside to obtain a sol;

[0011] (3) Mix polyethylene nanoparticles with deionized water at room temperature to obtain the medium;

[0012] (4) At room temperature, Schiele mineral is added to the medium described in step (3) to cause polyethylene nanoparticles and Schiele mineral to oscillate and aggregate, thus obtaining a mixed solution;

[0013] (5) After centrifuging the mixture described in step (4), discard the supernatant and take out the precipitate and dry it;

[0014] (6) Place the precipitate obtained in step (5) into the sol in step (2) and mix evenly until a mixed sol is formed;

[0015] (7) The mixed sol described in step (6) is added dropwise to the FeCl2 solution, and cross-linked at room temperature to obtain microspheres. The microspheres are then washed several times with deionized water to remove excess Fe. 2+ ;

[0016] (8) The microspheres described in step (7) are dried to obtain Schiele mineral-based microspheres.

[0017] Further, in step (1), the water bath heating temperature is 60-90 ℃, the stirring time is 30-60 min, and the sodium alginate aqueous solution has a sodium alginate mass concentration of 5-30 g / L.

[0018] Further, in step (2), the water bath heating temperature is 60-90 ℃, the stirring time is 60-90 min, and the mass concentration of corn starch in the sol is 35-140 g / L.

[0019] Further, in step (3), the polyethylene nanoparticles are selected as low-density polyethylene nanoparticles (LDPEs), and the concentration of polyethylene in the medium is 20 mg / L.

[0020] Furthermore, in step (4), Schielein is a naturally occurring iron-bearing mineral, commonly found in acidic mine drainage, and its structure contains a large amount of -OH and SO4. 2- The material contains active functional groups. Studies have found that Scheringer minerals have a highly efficient passivation ability for arsenic and can be used for the efficient passivation of arsenic in polluted water and soil. However, Scheringer minerals cannot be used for the passivation of the heavy metal cadmium, and their use in soil remediation processes may even increase cadmium bioactivity. Therefore, this invention combines Scheringer minerals with polyethylene nanoparticles to achieve simultaneous removal of cadmium and arsenic.

[0021] In one embodiment of the present invention, the Scheider mineral is prepared by the hydrogen peroxide oxidation method. The specific steps are as follows: ① Prepare 1 L of acidic aqueous solution with pH 3.0 using 98% concentrated sulfuric acid and place it in a beaker. Add 16.45 g of FeSO4•7H2O to 1 L of the above pH 3.0 solution and stir to dissolve. ② Under mechanical stirring (140 rpm), add 5.3 mL of 30% H2O2 solution at a rate of 1 mL / 120 min. During the synthesis process, NaOH needs to be added to maintain the pH of the system at 2.4-2.5 for 24 h to generate Scheider mineral (Sch). ③ Wash the generated Scheider mineral 3-5 times with a 1:1 mixture of deionized water and ethanol, centrifuge at 4500 rpm, collect the solid, and then freeze-dry it (-80℃). Grind the dried Scheider mineral into powder using a mortar and pestle and place it in a resealable bag for later use.

[0022] Further, in step (4), the concentration of Schiele mineral in the mixed solution is 10-100 mg / L, the pH of the aqueous environment in which the polyethylene nanoparticles and Schiele mineral oscillate and aggregate is 6-8, the pH of the initial solution is adjusted using hydrochloric acid or sodium hydroxide, the oscillation rate is 180-300 rpm, and the oscillation time is 60-300 min.

[0023] Further, in step (5), the centrifugation temperature is 20-30 ℃, the centrifugation speed is 5000-8000 r / min, the centrifugation time is 3-5 min, and the drying temperature is 20-30 ℃.

[0024] Further, in step (6), the amount of precipitate added to the sol in step (5) is 0.04-1.6 g / L; the mixture is stirred for 90-300 min at a temperature of 60-90 ℃.

[0025] Furthermore, in step (7), the mass concentration of the FeCl2 solution is 20-30 g / L, and the crosslinking time is 24-48 h. Ferric chloride, as a crosslinking agent, can increase the content of oxidant in the product.

[0026] Furthermore, in step (8), the drying temperature is 20-35 ℃ and the drying time is 18-24 h.

[0027] The present invention also provides Schiff mineral-based microspheres prepared by the method described above.

[0028] The present invention also provides applications of the microspheres, including adding the Scheres mineral-based microspheres to polluted water or soil according to the pollution status, and distributing them evenly in the polluted medium by stirring, thereby achieving a degradation effect.

[0029] Furthermore, the amount of pellets added depends on the cadmium and arsenic pollution level in the environment. When the cadmium concentration in the environment is ≤1 ppb and / or the arsenic concentration is ≤1 ppb, the application amount (by mass) per kilogram of polluted water or soil is 15%~20%. When the cadmium concentration in the environment is >1 ppb and / or the arsenic concentration is >1 ppb, the application amount per kilogram of polluted water or soil is 25%~30%.

[0030] In one embodiment of the present invention, when the cadmium concentration in the environment is ≤1 ppb and the arsenic concentration is ≤1 ppb, 0.15~0.20 kg of the microspheres are applied to each kilogram of polluted water / soil. When the cadmium concentration in the environment is >1 ppb and the arsenic concentration is >1 ppb, 0.25~0.30 kg of the microspheres are applied to each kilogram of polluted water / soil.

[0031] Furthermore, the pellets can be used to remediate cadmium and arsenic pollution in paddy fields. By evenly scattering the pellets into flooded paddy fields, they can reduce the amount of cadmium and arsenic in the soil.

[0032] Furthermore, the microspheres can be used for the remediation of cadmium and arsenic contaminated aqueous solutions. After being added to cadmium and arsenic contaminated water, the microspheres can effectively remove the total amount of cadmium and arsenic from the solution.

[0033] Furthermore, the microspheres can be used for the remediation of cadmium and arsenic contaminated soil. After the microspheres are evenly scattered into the cadmium and arsenic contaminated soil and the soil is loosened, the soil moisture content is adjusted artificially or through rainfall to reach more than 60%. At this point, the microspheres can achieve the effect of removing the total amount of cadmium and arsenic contamination from the soil.

[0034] As can be seen from the above technical solution, the present invention has the following beneficial effects:

[0035] 1. The starch and sodium alginate in the raw materials of this invention have excellent biocompatibility, are readily available, low in cost, non-toxic, harmless, and biodegradable. The Scheres mineral synthesis method is mature, simple to operate, time-efficient, and low in cost, especially the chemical oxidation method.

[0036] 2. This invention utilizes modified Scheres mineral recycling pellets for the remediation of cadmium and arsenic contaminated soil. The process is simple: the pellets are directly sprinkled into flooded paddy fields for in-situ remediation. After the remediation cycle, the pellets float on the surface of the flooded paddy field due to water absorption, allowing for recycling and reuse. Furthermore, the pellets can be applied year-round. Therefore, during non-rice growing seasons (such as winter or early spring in southern regions), the pellets can improve soil quality, increase soil fertility, and promote the activity of soil microorganisms, thereby promoting soil ecological balance. This can achieve rapid reduction of cadmium and arsenic in plant tissues and permanent removal of the total amount of cadmium in the soil. These pellets can be applied not only to contaminated paddy fields but also to ordinary soil and aquatic environments, making them widely applicable.

[0037] 3. In this invention, Scheringer's mineral, polyethylene, and starch all have adsorption effects on cadmium and arsenic in soil. Scheringer's mineral and polyethylene aggregate to form heterogeneous aggregates through ligand exchange and electrostatic interactions. Scheringer's mineral has abundant hydroxyl and sulfate groups on its surface, exhibiting a strong ability to fix cadmium and arsenic in the soil. Polyethylene has a high specific surface area and abundant pores; the aggregation of the two not only solves the problem of easy aggregation of Scheringer's mineral but also simultaneously removes cadmium and arsenic from the soil, effectively reducing the total amount of cadmium and arsenic in the soil. The addition of starch enhances the flexibility of the microspheres, and the addition of polyethylene enhances their mechanical strength. Simultaneously, the gel formed by starch and polyethylene creates a stable reaction environment for Scheringer's mineral, improving its ability to fix cadmium in the soil. Arsenic forms surface complexes on Scheringer's mineral through electrostatic adsorption, which further facilitates cadmium adsorption.

[0038] 4. During application, the pellets sink into the soil after entering the flooded paddy field due to their density being greater than that of water. Cadmium and arsenic ions in the soil are fixed on the pellets. While fixing cadmium and arsenic in the soil, the pellets absorb water and swell. After completing the remediation cycle, they float on the water surface, making them easy to recycle and reuse. The pellets have a compact structure, and the material is not easily dispersed, so it will not cause secondary pollution to the soil. The preparation method of this invention is simple, the conditions are mild, and the operation is simple. It only requires spreading the material into the soil, realizing the resource utilization of waste and allowing for large-scale preparation and promotion. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 Photograph of the recyclable cadmium and arsenic simultaneous removal Schiff mineral-based microspheres prepared in Example 1 of this invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be described in detail below with reference to specific embodiments. It should be understood that the embodiments described in this specification are merely illustrative and not intended to limit the scope of the invention.

[0042] Example 1

[0043] A recyclable Schiff mineral-based microsphere for simultaneous removal of cadmium and arsenic is prepared as follows:

[0044] (1) Prepare a 30 g / L sodium alginate aqueous solution, heat it in a 90 ℃ water bath and stir for 30 min to completely dissolve it;

[0045] (2) Add 90 g / L corn starch to the solution described in (1), heat in a water bath at 90 ℃, stir for 60 min until the solution becomes clear, cool to room temperature and set aside to obtain a sol;

[0046] (3) Mix low-density polyethylene with deionized water at room temperature. The concentration of low-density polyethylene is 20 mg / L to obtain the medium.

[0047] (4) At room temperature, add 60 mg / L Schiele mineral to the medium described in (3), wherein the Schiele mineral is prepared by the method described in the invention, and make the low-density polyethylene and Schiele mineral oscillate and aggregate. Adjust the pH of the initial solution with hydrochloric acid or sodium hydroxide so that the pH of the water environment in which the low-density polyethylene and Schiele mineral oscillate and aggregate is 6, the oscillation rate is 200 rpm, and the oscillation time is 180 min to obtain a mixed solution.

[0048] (5) After centrifuging the mixed solution described in (4) at 25 °C at 5000 r / min for 5 min, discard the supernatant, take out the precipitate, and dry it at 25 °C;

[0049] (6) Mix the material described in (5) at a concentration of 1.0 g / L in the sol of (2) until a mixed sol is formed; stir at 60 °C for 120 min.

[0050] (7) The sol described in (6) was added dropwise to a 20 g / L FeCl2 solution, and crosslinked at room temperature for 24 h to obtain microspheres. The microspheres were then washed several times with deionized water to remove excess Fe. 2+ ;

[0051] (8) The microspheres described in (7) are dried at 25 °C for 18 h to obtain Schiele mineral-based microspheres; Figure 1 The image shows the recyclable cadmium and arsenic simultaneous removal Scheres mineral-based microspheres prepared in Example 1, which have a diameter of about 2-3 mm.

[0052] Test Example 1

[0053] The effect of using recyclable cadmium and arsenic simultaneous removal Schiff mineral-based microspheres to remove cadmium and arsenic (Cd=10 mg / L, As=2 mg / L) from aqueous solution:

[0054] Take 50 ml of cadmium and arsenic contaminated solution and place it into a 250 ml Erlenmeyer flask. Add 0.5 g of the Scheres mineral-based microspheres prepared in Example 1, mix thoroughly, and incubate at room temperature for 3 days. After extracting the residual cadmium and arsenic in the solution, quantitative detection and analysis were performed using inductively coupled plasma mass spectrometry.

[0055] Simultaneously, a blank control experiment was established. 50 ml of cadmium-arsenic contaminated solution was placed in a 250 ml Erlenmeyer flask, thoroughly mixed, and incubated at room temperature for 3 days. The residual arsenic in the solution was extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0056] Comparative Example 1-1

[0057] Remediation of cadmium-contaminated solution (Cd=10 mg / L) using polyethylene nanoparticles

[0058] Take 50 ml of cadmium-contaminated solution and place it in a 250 ml Erlenmeyer flask. Add 0.07 g of polyethylene nanoparticles, mix thoroughly, and incubate at room temperature for 3 days. After extracting the residual cadmium in the solution, quantitative detection and analysis were performed using inductively coupled plasma mass spectrometry.

[0059] Comparative Example 1-1'

[0060] Remediation of cadmium-contaminated solution (Cd=10 mg / L) using Scheres minerals

[0061] Take 50 ml of cadmium-contaminated solution and place it in a 250 ml Erlenmeyer flask. Add 0.21 g of Schiele minerals, mix thoroughly, and incubate at room temperature for 3 days. After extracting the residual cadmium in the solution, quantitative detection and analysis were performed using inductively coupled plasma mass spectrometry.

[0062] Comparative Examples 1-2

[0063] Remediation of arsenic-contaminated solution (As=2 mg / L) using polyethylene nanoparticles

[0064] Take 50 ml of arsenic-contaminated solution and place it in a 250 ml Erlenmeyer flask. Add 0.07 g of polyethylene nanoparticles, mix thoroughly, and incubate at room temperature for 3 days. After extracting the residual arsenic from the solution, quantitative detection and analysis were performed using inductively coupled plasma mass spectrometry.

[0065] Comparative Examples 1-2'

[0066] Remediation of arsenic-contaminated solution (As=2 mg / L) using Scheres minerals

[0067] Take 50 ml of arsenic-contaminated solution and place it in a 250 ml Erlenmeyer flask. Add 0.21 g of Schiele mineral, mix thoroughly, and incubate at room temperature for 3 days. After extracting the residual arsenic in the solution, quantitative detection and analysis were performed using inductively coupled plasma mass spectrometry.

[0068] Comparative Examples 1-3

[0069] The Scheres mineral-based microspheres prepared in Example 1 of this invention were used to remediate a cadmium-contaminated solution (Cd = 10 mg / L).

[0070] Take 50 ml of cadmium-contaminated solution and place it into a 250 ml Erlenmeyer flask. Add 0.5 g of the Schiele mineral-based microspheres prepared in Example 1, mix thoroughly, and incubate at room temperature for 3 days. After extracting the residual cadmium in the solution, quantitative detection and analysis were performed using inductively coupled plasma mass spectrometry.

[0071] Comparative Examples 1-4

[0072] The Scheres mineral-based microspheres prepared in Example 1 of this invention were used to remediate an arsenic-contaminated solution (As = 2 mg / L).

[0073] Take 50 ml of arsenic-contaminated solution and place it into a 250 ml Erlenmeyer flask. Add 0.5 g of the Schiele mineral-based microspheres prepared in Example 1, mix thoroughly, and incubate at room temperature for 3 days. After extracting the residual arsenic in the solution, quantitative detection and analysis were performed using inductively coupled plasma mass spectrometry.

[0074] The removal performance of the microspheres of the present invention in Example 1 was compared and analyzed with that of the comparative example in cadmium and arsenic combined pollution / cadmium pollution / arsenic pollution solutions. The specific results are shown in Table 1:

[0075] Table 1

[0076]

[0077] Table 1 shows that after 3 days of cultivation without any remediation materials (blank), the removal rates of total cadmium and total arsenic in the solution were 0. Adding the microspheres of this invention (Test Example 1) simultaneously and efficiently removed total cadmium (85.30%) and total arsenic (60.50%) from the solution, demonstrating superior performance compared to solutions contaminated with only cadmium or arsenic. The removal capacity of single polyethylene nanoparticles or Schiele minerals (Comparative Examples 1-1, 1-1', 1-2, 1-2') for arsenic and cadmium was lower than that using the microspheres of this invention (Comparative Examples 1-3, 1-4).

[0078] Test Example 2

[0079] The effect of recyclable Scheres mineral-based microspheres on the removal of cadmium and arsenic (Cd=1.217mg / kg, As=73.43mg / kg) from paddy fields:

[0080] The removal of cadmium and arsenic from paddy fields using the Schiele mineral-based microspheres prepared in Example 1 of this invention:

[0081] 10 g of cadmium-arsenic co-contaminated paddy field soil was placed in a 250 ml Erlenmeyer flask, along with 2 g of Schiele mineral-based microspheres prepared in Example 1 and deionized water. Water management was performed according to standard farmland water management for rice growth, maintaining a 2 cm water layer throughout the culture period. The mixture was thoroughly mixed and cultured at room temperature for 7 days. Residual cadmium and arsenic in the soil were extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0082] Simultaneously, a blank control experiment was established. 10 g of cadmium-arsenic co-contaminated paddy field soil was placed in a 250 ml Erlenmeyer flask, deionized water was added, and water management followed the conventional farmland water management for rice growth. A 2 cm water layer was maintained during the incubation period, and the mixture was thoroughly mixed before incubation at room temperature for 7 days. The residual cadmium and arsenic in the soil were extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0083] Comparative Example 2-1

[0084] The Schröss mineral-based microspheres prepared in Example 1 of this invention were used to remediate cadmium-contaminated paddy fields.

[0085] 10 g of cadmium-contaminated paddy field soil was placed in a 250 ml Erlenmeyer flask, along with 2 g of the Schiele mineral-based microspheres prepared in Example 1 and deionized water. Water management was performed according to standard farmland water management for rice growth, maintaining a 2 cm water layer throughout the culture period. The mixture was thoroughly mixed and cultured at room temperature for 7 days. Residual cadmium and arsenic in the soil were extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0086] Comparative Example 2-2

[0087] The Schiele mineral-based microspheres prepared in Example 1 of this invention were used to remediate arsenic-contaminated paddy fields.

[0088] 10 g of arsenic-contaminated paddy field soil was placed in a 250 ml Erlenmeyer flask, along with 2 g of the Schiele mineral-based microspheres prepared in Example 1. Deionized water was added, and water management was carried out according to the conventional farmland water management for rice growth, maintaining a 2 cm water layer during the incubation period. The mixture was thoroughly mixed and incubated at room temperature for 7 days. The residual cadmium and arsenic in the soil were extracted and quantitatively analyzed using inductively coupled plasma mass spectrometry.

[0089] The removal performance of the microspheres of the present invention in Example 1 on cadmium and arsenic in soils contaminated with cadmium and arsenic in combination / cadmium / arsenic was compared and analyzed. The specific results are shown in Table 2:

[0090] Table 2

[0091]

[0092] As shown in Table 2, the removal rate of cadmium-arsenic combined contaminated soil with the addition of the microspheres of the present invention (total cadmium removal rate 69.73%, total arsenic removal rate 57.26%) is better than that of cadmium / arsenic single contaminated soil (total cadmium removal rate 65.49%, total arsenic removal rate 51.24%).

[0093] Test Example 3

[0094] The recycling effect of recyclable cadmium and arsenic simultaneous removal Schottky mineral-based microspheres in aqueous solution for cadmium and arsenic removal:

[0095] The Schiele mineral-based microspheres prepared in Example 1 were used to investigate the removal rate of cadmium and arsenic in solution after multiple applications. After each treatment, the microspheres were desorbed and recycled using 0.43 mol / L HNO3, and then the microspheres were reintroduced into the untreated original cadmium and arsenic contaminated solution. The degree to which the material's removal capacity was retained after three repeated uses of the Schiele mineral-based microspheres was tested. Other application methods were the same as in Example 1. The specific results are shown in Table 3.

[0096] Table 3

[0097]

[0098] As shown in Table 3, the effect of adding the microspheres of the present invention on the three-cycle treatment of cadmium and arsenic combined pollution solution is better than that on cadmium / arsenic single pollution solution.

[0099] Test Example 4

[0100] The recycling effect of recyclable cadmium and arsenic simultaneous removal Schottky mineral-based microspheres in paddy fields:

[0101] The Schiele mineral-based microspheres prepared in Example 1 were used to investigate the removal rate of cadmium and arsenic in soil after multiple applications. After each treatment, the microspheres were desorbed and recycled using 0.43 mol / L HNO3, and then the microspheres were reintroduced into the untreated original cadmium and arsenic contaminated soil. The degree to which the material's removal capacity was retained after three repeated applications of the Schiele mineral-based microspheres was tested. Other application methods were the same as in Example 2. The specific results are shown in Table 4.

[0102] Table 4

[0103]

[0104] As shown in Table 4, the effect of adding the microspheres of the present invention on the three-cycle treatment of cadmium and arsenic co-contaminated soil is better than that on cadmium / arsenic single-contaminated soil.

[0105] According to the above test examples 1-4, the remediation of cadmium / arsenic single / compound contaminated soil using the microspheres of the present invention is carried out by adding the microsphere head to the contaminated solution / contaminated soil, after which the microsphere can realize its function of removing cadmium / arsenic pollutants.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a recyclable cadmium and arsenic simultaneous removal schlenk mineral-based pellet, characterized by, Includes the following steps: (1) Add sodium alginate to water and heat it in a water bath while stirring to dissolve it completely, so as to obtain an aqueous solution of sodium alginate. (2) Add corn starch to the solution described in step (1), heat in a water bath, stir until the solution becomes clear, cool to room temperature and set aside to obtain a sol; (3) Mix polyethylene nanoparticles with deionized water at room temperature to obtain a medium; the polyethylene nanoparticles are selected as low-density polyethylene nanoparticles, and the concentration of the polyethylene nanoparticles in the medium is 20 mg / L; (4) At room temperature, Scheringer mineral is added to the medium described in step (3) to cause polyethylene nanoparticles and Scheringer mineral to oscillate and aggregate, thereby obtaining a mixed solution; the concentration of Scheringer mineral in the mixed solution is 10-100 mg / L, the pH of the water environment in which the polyethylene nanoparticles and Scheringer mineral oscillate and aggregate is 6-8, the initial solution pH is adjusted using hydrochloric acid or sodium hydroxide, the oscillation rate is 180-300 rpm, and the oscillation time is 60-300 min; (5) After centrifuging the mixture described in step (4), discard the supernatant and take out the precipitate and dry it; (6) Place the precipitate obtained in step (5) into the sol in step (2) and mix evenly until a mixed sol is formed; (7) The mixed sol from step (6) was added dropwise into the FeCl2solution, and microspheres were prepared after cross-linking at room temperature. The microspheres were washed several times with deionized water to remove excess Fe 2+ ; (8) The microspheres described in step (7) are dried to obtain Schiele mineral-based microspheres.

2. The process for the preparation of recyclable cadmium and arsenic simultaneous removal skarn mineral based prills as claimed in claim 1 wherein, In step (1), the water bath heating temperature is 60-90℃, the stirring time is 30-60min, and the sodium alginate aqueous solution has a sodium alginate mass concentration of 5-30g / L.

3. The process for the preparation of recyclable cadmium and arsenic simultaneous removal skarn based prills as claimed in claim 1 wherein, In step (2), the water bath heating temperature is 60-90℃, the stirring time is 60-90min, and the mass concentration of corn starch in the sol is 35-140g / L.

4. The process for the preparation of recyclable cadmium and arsenic simultaneous removal sphalerite-based prills as claimed in claim 1 wherein, In step (5), the centrifugation temperature is 20-30℃, the centrifugation speed is 5000-8000 r / min, the centrifugation time is 3-5 min, and the drying temperature is 20-30℃.

5. The process for the preparation of recyclable cadmium and arsenic simultaneous removal sphalerite-based prills as claimed in claim 1 wherein, In step (6), the amount of precipitate added to the sol in step (5) is 0.04-1.6 g / L; the mixture is stirred for 90-300 min at a temperature of 60-90 °C.

6. The process for the preparation of recyclable cadmium and arsenic simultaneous removal sphalerite-based prills as claimed in claim 1 wherein, In step (7), the mass concentration of the FeCl2 solution is 20-30 g / L, and the crosslinking time is 24-48 h.

7. Schiff mineral-based microspheres prepared by the method according to any one of claims 1 to 6.

8. Use of the Schlenk mineral-based pellets according to claim 7, characterized in that, Depending on the pollution level, the Scheres mineral-based microspheres are added to polluted water or soil, and then stirred to distribute them evenly in the polluted medium, thereby achieving a degradation effect.

Images