Phosphate modified Schwertmannite and synthetic method and application thereof

Abstract

The invention belongs to the technical field of environmental governance materials, and relates to phosphate modified Schwertmannite as well as a synthesis method and application thereof. The technical problem that the Schwertmannite cannot be effectively and synchronously removed due to opposite chemical behaviors of pollutants such as arsenic and cadmium in the prior art is solved. The invention provides a phosphate modified Schwertmannite which comprises Schwertmannite and phosphate, the ratio of the amount of substance of the Schwertmannite to the amount of substance of the phosphate is 1: 0.01-0.5, and arsenic and cadmium in the environment can be effectively and synchronously removed. The invention further provides a synthesis method of the phosphate modified Schwertmannite, the Schwertmannite and phosphate are subjected to ball-milling mixing, ball-milling modification is utilized, the technical method is simple, practicability is high, no waste water or waste is generated in the preparation process, and use is safe. Meanwhile, the invention further provides application of the phosphate modified Schwertmannite, the phosphate modified Schwertmannite is used for repairing the arsenic and / or cadmium heavy metal polluted environment, and the effect is better than that of unmodified Schwertmannite.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental management materials, and in particular, relates to a phosphate-modified Schreiberite mineral and a synthesis method and application thereof. Background Art

[0002] Heavy metal pollution refers to the phenomenon that the concentration of certain heavy metal elements or their compounds in the environment exceeds the natural background value or exceeds the environmental capacity, which has adverse effects on the environment and human health. These heavy metal elements include but are not limited to lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), chromium (Cr), copper (Cu), nickel (Ni) and zinc (Zn). Among them, cadmium and arsenic are highly toxic (type) metals that pollute farmland worldwide, posing a huge threat to human health. The problem of heavy metal compound pollution near industrial and mining enterprises and smelters is prominent, and often brings challenges to soil remediation and management. Excessive arsenic and cadmium content will cause the degradation of soil fertility and soil quality, affect the symptoms of toxicity in plants, enter the human body through the food chain, and endanger human health. As typical anion and cation pollutants, arsenic and cadmium compound pollution is one of the difficulties in my country's current soil pollution control, because arsenic and cadmium have significant differences in geochemical behavior and bioavailability. Therefore, the development of passivation materials that can simultaneously repair arsenic and cadmium pollution is of great significance to environmental heavy metal management.

[0003] Schmidtite is a naturally occurring iron-containing mineral that is commonly found in acid mine drainage. Schmidtite is a poorly crystalline, metastable secondary ferric hydroxysulfate mineral with a large amount of -OH and SO in its structure. 2 4 - Active functional groups such as schreberite have high efficiency in passivating arsenic and can be used for high efficiency passivation of arsenic in polluted water and soil. Studies have found that the maximum adsorption capacity of schreberite for trivalent arsenic is as high as 100mg / g~250mg / g, and its passivation ability is much higher than other iron minerals such as lepidocrocite, ferrihydrite, hematite, and goethite. However, schreberite cannot be used for the passivation of heavy metal cadmium, and its use in soil remediation may even increase the biological activity of cadmium. This is mainly because schreberite releases sulfate ions during the application process, which will cause the pH of the solution to decrease, thereby significantly increasing the mobility of cadmium. Studies have shown that when the pH is less than 5.0, the adsorption of cadmium is almost completely inhibited.

[0004] Therefore, it is necessary to provide an effective method for modifying Schroeder mineral to improve its passivation ability against arsenic and cadmium co-pollution and provide a feasible remediation material for the remediation of arsenic and cadmium heavy metal contaminated water and soil in my country. Summary of the invention

[0005] 1. Problems to be solved

[0006] In view of the technical problem in the prior art that heavy metal pollutants arsenic and cadmium cannot be effectively and synchronously removed by Schreiber mineral due to their opposite chemical behaviors, the present application provides a phosphate-modified Schreiber mineral that can effectively and synchronously remove arsenic and cadmium from the environment. The present application also provides a method for synthesizing the phosphate-modified Schreiber mineral, and the present application also provides the application of the phosphate-modified Schreiber mineral.

[0007] 2. Technical solution

[0008] In order to achieve the above purpose, the technical solution provided is:

[0009] A phosphate-modified Schroeder mineral comprises Schroeder mineral and phosphate, wherein the molar ratio of the Schroeder mineral to the phosphate is 1:0.01-0.5.

[0010] Furthermore, the specific surface area of ​​the phosphate-modified Schroederite is 45 m 2 / g~194m 2 / g.

[0011] Furthermore, the phosphate is potassium dihydrogen phosphate and / or ammonium dihydrogen phosphate.

[0012] Preferably, the Fe / S molar ratio of the Schroederite is 5.7.

[0013] A method for synthesizing phosphate-modified Schroeder mineral comprises the steps of mixing the Schroeder mineral with phosphate by ball milling to obtain the phosphate-modified Schroeder mineral; the molar ratio of the Schroeder mineral to the phosphate is 1:0.01-0.5.

[0014] Furthermore, the ball-to-grinding material ratio of the ball mill is 100-250:1.

[0015] Furthermore, the ball milling is performed using a planetary ball mill, the ball milling speed is 300 rpm to 600 rpm, and the ball milling time is 3 h to 5 h.

[0016] Furthermore, the ball milling medium is zirconia ball milling beads, and the diameter of the zirconia ball milling beads is 3 mm to 10 mm.

[0017] Furthermore, the zirconium oxide ball milling beads include zirconia ball milling beads A, zirconia ball milling beads B and zirconia ball milling beads C, the diameter of the zirconia ball milling beads A is 10.0mm~10.2mm, the diameter of the zirconia ball milling beads B is 5.0mm~5.2mm, and the diameter of the zirconia ball milling beads C is 3.0mm~3.2mm.

[0018] Furthermore, the mass ratio of the zirconia ball milling beads A, zirconia ball milling beads B and zirconia ball milling beads C is 1:3:6.

[0019] An application of a phosphate-modified Schrödinger mineral, the application of the phosphate-modified Schrödinger mineral in repairing an environment polluted by arsenic and / or cadmium heavy metals, or the application of the phosphate-modified Schrödinger mineral prepared by the method in repairing an environment polluted by arsenic and / or cadmium heavy metals.

[0020] Preferably, the application also includes selecting a single phosphate-modified Schreiberite repair agent according to the actual pollution status of the soil and water, or using it in combination with other passivators to achieve a more efficient treatment effect.

[0021] 3. Beneficial effects

[0022] Compared with the existing known technology, the technical solution provided by the present invention has the following beneficial effects:

[0023] (1) A phosphate-modified Schreiber mineral of the present invention comprises a Schreiber mineral and a phosphate, wherein the molar ratio of the Schreiber mineral to the phosphate is 1:0.01-0.5. After the phosphate-modified Schreiber mineral, the morphology is significantly changed, and the mineral changes from a relatively smooth elliptical spherical shape to an irregular nanosphere stacking structure, and the specific surface area is increased from 30.6 m 2 / g (unmodified) increased to 157.7m 2 / g, with more active sites, which is beneficial to improve the adsorption capacity; the content of sulfate in phosphate-modified Schreiberite is reduced, while the content of phosphate is increased, thereby avoiding a sharp drop in environmental pH, overcoming the opposite chemical behaviors of heavy metal arsenic and cadmium, and being able to effectively and synchronously remove arsenic and cadmium from the environment.

[0024] (2) A method for synthesizing a phosphate-modified Schmidtite of the present invention comprises mixing the Schmidtite with phosphate by ball milling to obtain the phosphate-modified Schmidtite, wherein the molar ratio of the Schmidtite to the phosphate is 1:0.01-0.5. The raw materials used in the present invention are simple and easy to obtain, low in price, and low in dosage. No wastewater and waste are generated during the preparation process, and the use is safe. The present invention utilizes ball milling modification, has a simple technical method, strong practicality, mild reaction conditions, easy construction and operation, high productivity, high repeatability, no excessive requirements on equipment, and can be used for large-scale experiments, with significant economic, environmental and social effects.

[0025] (3) Application of a phosphate-modified Schmidt mineral of the present invention, wherein the content of sulfate in the phosphate-modified Schmidt mineral is reduced, while the content of phosphate is increased, thereby avoiding a sharp drop in the environmental pH and preventing the mobility and bioavailability of cadmium from being increased during use; at the same time, the purpose of reducing the mobility of cadmium by using the phosphate coprecipitation process is achieved, and the characteristics of the opposite chemical behaviors of heavy metals arsenic and cadmium can be overcome, and heavy metals arsenic and cadmium can be passivated simultaneously, thereby effectively improving the passivation ability of the phosphate-modified Schmidt mineral for cadmium heavy metals, and realizing the repair treatment of arsenic-cadmium co-pollution. The phosphate-modified Schmidt mineral is used to repair arsenic heavy metal pollution environments, cadmium heavy metal pollution environments, and arsenic-cadmium co-existence heavy metal pollution environments, and the effects are better than those of the unmodified Schmidt mineral. Moreover, the removal effect of the phosphate-modified Schmidt mineral on cadmium in the co-existence pollution system of arsenic and cadmium is higher than the removal effect of cadmium in the pollution system where cadmium exists alone. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The morphology of the phosphate-modified Schroederite and the unmodified Schroederite in Example 1;

[0027] Figure 2 The adsorption capacity of arsenic by the phosphate-modified Schroederite prepared in Example 1;

[0028] Figure 3 The adsorption capacity of cadmium by the phosphate-modified Schroederite prepared in Example 2;

[0029] Figure 4 The treatment effect of the phosphate-modified Schmidtite prepared in Example 1 on arsenic-cadmium co-contaminated water;

[0030] Figure 5 The treatment effect of the phosphate-modified Schmidtite prepared in Example 2 on arsenic-cadmium co-contaminated water;

[0031] Figure 6 is the adsorption capacity of unmodified Schroederite for arsenic;

[0032] Figure 7 is the adsorption capacity of unmodified Schroederite for cadmium;

[0033] Figure 8 This is the treatment effect of unmodified Schroeder mineral on arsenic-cadmium co-contaminated water. DETAILED DESCRIPTION

[0034] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with embodiments.

[0035] Example 1

[0036] A method for synthesizing phosphate-modified Schroederite of this embodiment comprises the following steps:

[0037] Weigh 7.65g of Schroederite and 0.136g of potassium dihydrogen phosphate and place them in a ball mill filled with argon gas;

[0038] The ball mill was placed in a planetary ball mill, the ball milling speed was 500 rpm, the ball milling time was 4 h, and the ball milling ratio (the mass ratio of the ball milling medium to the material to be ground, i.e., the mixture of Schroeder mineral and potassium dihydrogen phosphate) was 225:1;

[0039] After the ball milling was completed, the ball milling medium was separated by a sieve to obtain phosphate-modified Schrödinger mineral (P-Sch), and the molar ratio of potassium dihydrogen phosphate to Schrödinger mineral was 0.1 (P / S=0.1).

[0040] The ball milling medium is zirconia ball milling beads, which include zirconia ball milling beads A with a particle size of 10 mm, zirconia ball milling beads B with a particle size of 5 mm, and zirconia ball milling beads C with a particle size of 3 mm; the mass ratio of zirconia ball milling beads A, zirconia ball milling beads B and zirconia ball milling beads C is 1:3:6.

[0041] In this embodiment, the morphology of the Schmidtite mineral after phosphate modification changes significantly, and the mineral changes from a relatively smooth elliptical spherical shape to an irregular nanosphere stacking structure. Figure 1 As shown in the figure, the specific surface area of ​​the Schroederite after phosphate modification increased from 30.6 m 2 / g increased to 157.7m 2 / g. This indicates that under the action of mechanical force, the incorporation of phosphate makes Schroeder mineral have more active sites, which is beneficial to improving the adsorption capacity.

[0042] Example 2

[0043] A method for synthesizing phosphate-modified Schroederite of this embodiment comprises the following steps:

[0044] Weigh 7.65g of Schroederite and 0.68g of potassium dihydrogen phosphate and place them in a ball mill filled with argon gas;

[0045] The ball mill was placed in a planetary ball mill, the ball milling speed was 500 rpm, the ball milling time was 4 h, and the ball milling ratio (the mass ratio of the ball milling medium to the material to be ground, i.e., the mixture of Schroeder mineral and potassium dihydrogen phosphate) was 225:1;

[0046] After the ball milling was completed, the ball milling medium was separated by a sieve to obtain phosphate-modified Schrödinger mineral (P-Sch), wherein the molar ratio of potassium dihydrogen phosphate to Schrödinger mineral was 0.5 (P / S=0.5).

[0047] The ball milling medium is zirconia ball milling beads, which include zirconia ball milling beads A with a particle size of 10 mm, zirconia ball milling beads B with a particle size of 5 mm, and zirconia ball milling beads C with a particle size of 3 mm; the mass ratio of zirconia ball milling beads A, zirconia ball milling beads B and zirconia ball milling beads C is 1:3:6.

[0048] In this embodiment, the morphology of the Schroeder mineral after phosphate modification changes significantly, and the mineral changes from a relatively smooth elliptical sphere to an irregular nanosphere stacking structure. 2 / g increased to 64.4m 2 / g. This indicates that under the action of mechanical force, the incorporation of phosphate makes Schroeder mineral have more active sites, which is beneficial to improving the adsorption capacity.

[0049] Example 3

[0050] A method for synthesizing phosphate-modified Schroederite of this embodiment comprises the following steps:

[0051] Weigh 7.65g of Schroederite and 0.0136g of potassium dihydrogen phosphate and place them in a ball mill filled with argon gas;

[0052] The ball mill was placed in a planetary ball mill, the ball milling speed was 500 rpm, the ball milling time was 4 h, and the ball milling ratio (the mass ratio of the ball milling medium to the material to be ground, i.e., the mixture of Schroeder mineral and potassium dihydrogen phosphate) was 225:1;

[0053] After the ball milling, the ball milling medium was separated by a sieve to obtain phosphate-modified Schrödinger mineral (P-Sch), wherein the molar ratio of potassium dihydrogen phosphate to Schrödinger mineral was 0.01 (P / S=0.01).

[0054] The ball milling medium is zirconia ball milling beads, which include zirconia ball milling beads A with a particle size of 10 mm, zirconia ball milling beads B with a particle size of 5 mm, and zirconia ball milling beads C with a particle size of 3 mm; the mass ratio of zirconia ball milling beads A, zirconia ball milling beads B and zirconia ball milling beads C is 1:3:6.

[0055] In this embodiment, the morphology of the Schroeder mineral after phosphate modification changes significantly, and the mineral changes from a relatively smooth elliptical sphere to an irregular nanosphere stacking structure. 2 / g increased to 45.2m 2 / g. This indicates that under the action of mechanical force, the incorporation of phosphate makes Schroeder mineral have more active sites, which is beneficial to improving the adsorption capacity.

[0056] Example 4

[0057] The application of a phosphate-modified Schroeder mineral in this embodiment, and the maximum adsorption capacity of the phosphate-modified Schroeder mineral for As(III), comprises the following steps:

[0058] Accurately weigh 0.04 g of the phosphate-modified Schroeder mineral obtained in Example 1 and add them to a gradient As(III) solution with a concentration of 10 mg / L, 15 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, and a volume of 100 mL. The solution pH is adjusted to 5.0, and then placed in a shaker at 28 ° C and 180 rpm. The pH of the reaction system is maintained at 5.0 ± 0.1 with 0.01 M (ie, 0.01 mol / L) HNO3 and 0.01 M (ie, 0.01 mol / L) NaOH. After 24 hours, the arsenic content is determined after sampling through a 0.45 μm filter membrane. The final results are shown in the following table. Figure 2 .

[0059] After testing, in this embodiment, the phosphate-modified Schreiberite obtained in Example 1 has a very efficient adsorption capacity for As(III), the adsorption isotherm conforms to the Langmuir curve, and the calculated maximum adsorption capacity is as high as 55.3 mg / g.

[0060] Example 5

[0061] The application of a phosphate-modified Schroeder mineral in this embodiment, and the maximum adsorption capacity of the phosphate-modified Schroeder mineral for Cd(II), comprises the following steps:

[0062] Accurately weigh 0.040g of the phosphate-modified Schroeder mineral obtained in Example 2 and add them to a gradient Cd(II) solution with a concentration of 5mg / L, 10mg / L, 30mg / L, 40mg / L, and 60mg / L, and a volume of 100mL. The solution pH is adjusted to 5.0, and then placed in a shaker at 28°C and 180rpm. The pH of the reaction system is maintained at 5.0±0.1 with 0.01M HNO3 and 0.01M NaOH. After 24h, the cadmium content is determined after sampling through a 0.45μm filter membrane. The final results are shown in the following table. Figure 3 .

[0063] In this embodiment, the phosphate-modified Schroederite obtained in Example 2 has a very efficient adsorption capacity for Cd(II), the adsorption isotherm conforms to the Langmuir curve, and the calculated maximum adsorption capacity is as high as 67.6 mg / g.

[0064] Example 6

[0065] The application of a phosphate-modified Schroeder mineral in this embodiment, and the treatment of arsenic and cadmium pollution by the phosphate-modified Schroeder mineral (obtained in Example 1), comprises the following steps:

[0066] Weigh 0.040 g of phosphate-modified Schroederite and add it to a 100 mL mixed solution of As(III) and Cd(II). Place it in a shaker at 28°C and 180 rpm. Use 0.01 M HNO3 and 0.01 M NaOH to maintain the pH of the reaction system at 5.0 ± 0.1. After 24 hours, take a sample and filter it through a 0.45 μm filter to determine the arsenic and cadmium contents. The final results are shown in the table. Figure 4 .

[0067] In the mixed solution of As(III) and Cd(II), the concentrations of Cd(II) were 5 mg / L, 10 mg / L, 30 mg / L, 40 mg / L, and 60 mg / L, respectively; the corresponding concentrations of As(III) were 10 mg / L, 15 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, respectively.

[0068] In this example, the phosphate-modified Schmidtite showed good removal effects on both arsenic and cadmium. The results showed that the adsorption equilibrium amounts of phosphate-modified Schmidtite for arsenic were 4.3 mg / g, 8.9 mg / g, 12.8 mg / g, 24.1 mg / g, and 28.7 mg / g, respectively; and the adsorption equilibrium amounts of cadmium were 2.1 mg / g, 5.0 mg / g, 12.2 mg / g, 14.6 mg / g, and 20.4 mg / g, respectively. This indicates that the phosphate-modified Schmidtite can remove As(III) and Cd(II) simultaneously.

[0069] Example 7

[0070] The application of a phosphate-modified Schroeder mineral in this embodiment, and the treatment of arsenic and cadmium pollution by the phosphate-modified Schroeder mineral (obtained in Example 2), comprises the following steps:

[0071] Weigh 0.040 g of phosphate-modified Schroederite and add it to a 100 mL mixed solution of As(III) and Cd(II). Place it in a shaker at 28°C and 180 rpm. Use 0.01 M HNO3 and 0.01 M NaOH to maintain the pH of the reaction system at 5.0 ± 0.1. After 24 hours, take a sample and filter it through a 0.45 μm filter to determine the arsenic and cadmium contents. The final results are shown in the table. Figure 5 .

[0072] In the mixed solution of As(III) and Cd(II), the concentrations of Cd(II) were 5 mg / L, 10 mg / L, 30 mg / L, 40 mg / L, and 60 mg / L, respectively; the corresponding concentrations of As(III) were 10 mg / L, 15 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, respectively.

[0073] In this embodiment, phosphate-modified Schmidtite showed good removal effects on both arsenic and cadmium. The results showed that the adsorption equilibrium amounts of phosphate-modified Schmidtite for arsenic were 5.5 mg / g, 6.1 mg / g, 7.2 mg / g, 8.3 mg / g, and 13.0 mg / g, respectively; the adsorption equilibrium amounts of cadmium were 12.8 mg / g, 25.3 mg / g, 64.6 mg / g, 85.3 mg / g, and 113.0 mg / g, respectively. This shows that phosphate-modified Schmidtite can remove As(III) and Cd(II) at the same time, and the removal effect of phosphate-modified Schmidtite on cadmium in the coexistence pollution system of arsenic and cadmium is higher than that in the pollution system where cadmium exists alone.

[0074] The Fe / S molar ratio of the Schmidtite in the present application is 5.7, and the present application is also applicable to other Fe / S molar ratios of the Schmidtite.

[0075] Comparative Example 1

[0076] This comparative example provides the application of unmodified Schroeder mineral, and the maximum adsorption capacity of unmodified Schroeder mineral for As(III), comprising the following steps:

[0077] Accurately weigh 0.04g of unmodified Schroeder mineral and add it to a gradient As(III) solution with a concentration of 10mg / L, 15mg / L, 30mg / L, 40mg / L, and 50mg / L, with a volume of 100mL. Adjust the solution pH to 5.0, then place it in a shaker at 28°C and 180rpm, and use 0.01M HNO3 and 0.01M NaOH to maintain the pH of the reaction system at 5.0±0.1. After 24h, sample it and filter it through a 0.45μm filter membrane to determine the arsenic content. The final results are shown in the following table. Figure 6 .

[0078] The test showed that the As(III) removal effect of the unmodified Schreiberite was not as good as that of the phosphate-modified Schreiberite (P / S=0.1) obtained in Example 1. The adsorption isotherm was consistent with the Langmuir curve, and the calculated maximum adsorption capacity was 39.1 mg / g.

[0079] Comparative Example 2

[0080] This comparative example provides the application of unmodified Schroeder mineral, and the maximum adsorption capacity of unmodified Schroeder mineral for Cd(II) comprises the following steps:

[0081] Accurately weigh 0.040g of unmodified Schroeder mineral and add it to 100mL of gradient Cd(II) solution with concentrations of 5mg / L, 10mg / L, 30mg / L, 40mg / L, and 60mg / L, respectively. Adjust the solution pH to 5.0, then place it in a shaker at 28°C and 180rpm, and use 0.01M HNO3 and 0.01M NaOH to maintain the pH of the reaction system at 5.0±0.1. After 24h, sample it and filter it through a 0.45μm filter membrane to determine the cadmium content. The final results are shown in the table. Figure 7 .

[0082] After testing, the unmodified Schreiner mineral is not as effective as the phosphate-modified Schreiner mineral (P / S=0.5) obtained in Example 2 in removing Cd(II). The adsorption isotherm conforms to the Langmuir curve, and the calculated maximum adsorption capacity is 41.1 mg / g.

[0083] Comparative Example 3

[0084] This comparative example provides the application of unmodified Schroeder mineral, and the treatment ability of unmodified Schroeder mineral on arsenic and cadmium pollution, comprising the following steps:

[0085] Weigh 0.040g of unmodified Schroederite and add it to a 100mL mixed solution of As(III) and Cd(II). Place it in a shaker at 28°C and 180rpm. Use 0.01M HNO3 and 0.01M NaOH to maintain the pH of the reaction system at 5.0±0.1. After 24h, take a sample and filter it through a 0.45μm filter to determine the arsenic and cadmium content. The final results are shown in the table. Figure 8 .

[0086] In the mixed solution of As(III) and Cd(II), the concentrations of Cd(II) were 5 mg / L, 10 mg / L, 30 mg / L, 40 mg / L, and 60 mg / L, respectively; the corresponding concentrations of As(III) were 10 mg / L, 15 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, respectively.

[0087] After testing, the adsorption equilibrium of unmodified Schroeder mineral for arsenic was 8.3mg / g, 9.3mg / g, 14.2mg / g, 28.2mg / g, and 30.2mg / g, respectively; the adsorption equilibrium of cadmium was 1.6mg / g, 2.7mg / g, 5.0mg / g, 7.2mg / g, and 8.0mg / g, respectively. In the arsenic and cadmium coexisting pollution system, the adsorption of cadmium by unmodified Schroeder mineral was significantly reduced, while phosphate modification could significantly improve the ability of Schroeder mineral to passivate Cd(II).

[0088] In summary, the present application utilizes phosphate ball milling modification to modify the composition and structure of Schmidt mineral, and by regulating the amount of potassium dihydrogen phosphate added, the ball milling material ratio, the ball milling speed, the ball milling time and other parameters, the phosphate-modified Schmidt mineral obtained can be used for the treatment of arsenic-cadmium co-polluted environment. The morphology of the Schmidt mineral after phosphate modification changes significantly, and the mineral evolves from an elliptical sphere with a relatively smooth surface to an irregular nanosphere stacking structure, with an increased specific surface area, more active sites, and an increased adsorption capacity; the content of sulfate in the phosphate-modified Schmidt mineral is reduced, while the content of phosphate is increased, thereby avoiding a sharp drop in environmental pH and preventing the mobility and bioavailability of cadmium from being increased during use; at the same time, the purpose of reducing the mobility of cadmium by using the phosphate coprecipitation process is achieved, and the opposite characteristics of the chemical behavior of heavy metal arsenic and cadmium can be overcome, and the synchronous passivation of cadmium can be achieved, thereby achieving simultaneous repair of arsenic and cadmium, and effectively solving the problems in the prior art.

[0089] The above-mentioned embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person skilled in the art, several modifications, improvements and substitutions can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims

1. A phosphate-modified Schroederite, characterized in that: The invention comprises a Schroeder mineral and a phosphate, wherein the amount ratio of the Schroeder mineral to the phosphate is 1:0.01-0.

5.

2. The phosphate-modified Schroederite according to claim 1, characterized in that: The specific surface area of ​​the phosphate-modified Schroederite is 45 m 2 / g~194m 2 / g.

3. A phosphate-modified Schroederite according to any one of claims 1 or 2, characterized in that: The phosphate is potassium dihydrogen phosphate and / or ammonium dihydrogen phosphate.

4. A method for synthesizing phosphate-modified Schroederite, characterized in that: The phosphate-modified Schroeder mineral is obtained by ball-milling and mixing the Schroeder mineral and the phosphate; the molar ratio of the Schroeder mineral to the phosphate is 1:0.01-0.

5.

5. The method for synthesizing phosphate-modified Schroederite according to claim 4, characterized in that: The ball-milling material ratio is 100-250:

1.

6. The method for synthesizing phosphate-modified Schroederite according to claim 5, characterized in that: The ball milling is performed using a planetary ball mill, the rotation speed of the ball milling is 300 rpm to 600 rpm, and the ball milling time is 3 h to 5 h.

7. The method for synthesizing phosphate-modified Schroederite according to claim 6, characterized in that: The ball milling medium is zirconia ball milling beads, and the diameter of the zirconia ball milling beads is 3mm to 10mm.

8. The method for synthesizing phosphate-modified Schroederite according to claim 7, characterized in that: The zirconium oxide ball milling beads include zirconia ball milling beads A, zirconia ball milling beads B and zirconia ball milling beads C. The diameter of the zirconia ball milling beads A is 10.0mm to 10.2mm, the diameter of the zirconia ball milling beads B is 5.0mm to 5.2mm, and the diameter of the zirconia ball milling beads C is 3.0mm to 3.2mm.

9. The method for synthesizing phosphate-modified Schroederite according to claim 8, characterized in that: The mass ratio of the zirconia ball milling beads A, zirconia ball milling beads B and zirconia ball milling beads C is 1:3:

6.

10. An application of phosphate-modified Schroederite, characterized in that: Use of the phosphate-modified Schroeder mineral described in any one of claims 1 to 3 in repairing an environment polluted by arsenic and / or cadmium heavy metals, or use of the phosphate-modified Schroeder mineral prepared by the method described in any one of claims 4 to 9 in repairing an environment polluted by arsenic and / or cadmium heavy metals.

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