A material for heavy metal mineralization and its preparation method and application

Abstract

The application provides a material for heavy metal mineralization and a preparation method and application thereof, and belongs to the technical field of soil remediation. The preparation method of the material for heavy metal mineralization comprises the following steps: mixing a silicate solution and a hardly soluble phosphate to carry out a substitution reaction, so as to obtain a mixed solution; and mixing the mixed solution with an acid solution to carry out gelation and drying, so as to obtain the material for heavy metal mineralization. The silicate solution is mixed with the hardly soluble phosphate to carry out a reaction, so that the phosphate in the hardly soluble phosphate enters the solution, and the reactivity of the material in the use process is improved. The gelation by adding the acid solution can effectively prevent the generation of phosphorus-containing wastewater. The drying makes the material into a porous structure, more active sites are provided for heavy metal adhesion, and then the heavy metal is better fixed. The results of the examples show that the material for heavy metal mineralization prepared by the application has a good heavy metal remediation effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil remediation, and in particular to a material for heavy metal mineralization and a preparation method and application thereof. BACKGROUND

[0002] Heavy metal pollution seriously endangers ecological environment safety and human health. Common heavy metals mainly include Cd, Pb, Cu, Zn, Ni, etc., in addition, metalloid elements As and Sb also have similar biological toxicity to the above heavy metal elements. After heavy metal pollution of soil, it cannot be biodegraded and can be accumulated through the food chain, seriously endangering ecological environment safety and green economic development. And heavy metals have cumulative and high toxicity, long-term exposure of human body to heavy metals can cause bone pain disease, lung cancer and kidney function damage and other adverse effects. Therefore, heavy metal and metalloid pollution has become an urgent environmental problem to be solved.

[0003] Stabilization remediation technology has been widely used in remediation of heavy metal contaminated soil. Stabilization remediation technology is a remediation technology that forms stable chemical bonds with heavy metals by adding remediation materials, thereby reducing the mobility of heavy metals. Among them, the use of phosphate-based remediation materials to stabilize soil heavy metals is a remediation method that has been studied more and has great application prospect. Phosphate-based remediation materials not only can improve soil fertility, but also can form stable metal-phosphate compounds with heavy metals to stabilize soil heavy metals. However, the current phosphate-based remediation materials are prone to produce phosphorus-containing wastewater during preparation, and most of the phosphate remediation materials have low reactivity and low adsorption capacity, so that the material consumption is large and the social and economic benefits are low when treating heavy metal contaminated soil.

[0004] In related research, acid-activated red mud, phosphate-containing wastewater and culture medium were mixed and cultured to prepare a heavy metal adsorption material, but the prepared phosphorus-containing material has low adsorption capacity, and after solid-liquid separation, the wastewater still contains a certain amount of phosphorus elements; there is also related research that prepares a multi-metal synchronous stabilization functional material by adjusting the ratio of Fe, Mn and P, which has a simple preparation process, but the wastewater contains a large amount of phosphate and hydrogen phosphate; there is also related research that uses microorganisms to modify phosphorus-containing ore to prepare a heavy metal passivation agent, which solves the problem of phosphorus-containing tailings accumulation, but cannot form stable minerals with soil heavy metals, and there is a risk of secondary release of heavy metals. SUMMARY

[0005] The present application provides a material for heavy metal mineralization and a preparation method and application thereof. The preparation method provided by the present application does not produce phosphorus-containing wastewater during preparation, has no secondary pollution, and the prepared material for heavy metal mineralization can form phosphate minerals with heavy metals, and has good heavy metal remediation effect.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of a material for heavy metal mineralization, comprising the following steps:

[0008] (1) mixing a solution of silicate with a hardly soluble phosphate to carry out a substitution reaction, to obtain a mixed solution;

[0009] (2) mixing the mixed solution obtained in the step (1) with an acid solution to carry out gelation and then drying, to obtain the material for heavy metal mineralization.

[0010] Preferably, the concentration of SiO3 2- in the solution of silicate in the step (1) is 0.6-1.2 mol / L.

[0011] Preferably, the modulus of the silicate in the step (1) is 2.0-3.5.

[0012] Preferably, the molar ratio of phosphorus element in the hardly soluble phosphate to the silicate in the step (1) is (0.1-2):(0.6-1.2).

[0013] Preferably, the hardly soluble phosphate in the step (1) comprises one or more of ferric phosphate, ferrous phosphate, calcium phosphate and aluminum phosphate.

[0014] Preferably, the temperature of the substitution reaction in the step (1) is 5-50℃, and the time of the substitution reaction is 1-4 h.

[0015] Preferably, the acid solution in the step (2) comprises an inorganic acid solution and / or a dihydrogen phosphate solution; the inorganic acid solution comprises one or more of a sulfuric acid solution, a nitric acid solution, a hydrochloric acid solution and a phosphoric acid solution.

[0016] Preferably, the pH value of the gelation in the step (2) is 7-10.5.

[0017] The present application also provides the material for heavy metal mineralization prepared by the preparation method.

[0018] The present application also provides the application of the material for heavy metal mineralization in adsorbing heavy metal and / or metalloid ions.

[0019] The application provides a preparation method of a material for heavy metal mineralization, which comprises the following steps: (1) mixing a silicate solution with a hardly soluble phosphate to carry out a substitution reaction, so as to obtain a mixed solution; and (2) mixing the mixed solution obtained in the step (1) with an acid solution to carry out gelation and then drying, so as to obtain the material for heavy metal mineralization. The silicate solution is mixed with the hardly soluble phosphate to carry out a reaction, so that the SiO3 2- , OH - in the silicate solution is substituted by PO4 3- in the hardly soluble phosphate, the phosphate in the hardly soluble phosphate is released into the solution, and a polyhydroxy phosphate is generated, and the OH - can also form a metal hydroxide with the metal in the hardly soluble phosphate. The substitution reaction promotes the release of the phosphate in the hardly soluble phosphate, greatly improves the reactivity of the material in use, and can make the material slowly release the phosphate and the hydrogen phosphate in use, so that the heavy metal ions are combined with the phosphate and the groups thereof, and a stable metal-phosphate mineral is formed on the surface of the material. The gelation by adding the acid solution can effectively prevent the generation of the phosphorus-containing wastewater. The material for heavy metal mineralization is changed into a porous structure by drying, so as to provide more active sites for the heavy metal attachment. The addition of the silicate and the substitution reaction make the material surface contain a large amount of Si-OH and -OH groups, the heavy metal ions can be combined on the material surface through a deprotonation reaction to form an inner coordination compound, and then the heavy metal is fixed. Meanwhile, the silicon-oxygen network structure in the silica formed after the gelation also realizes the controllable release of the phosphorus in use.

[0020] The results of the examples show that, after the material for heavy metal mineralization prepared by the application is added into the contaminated soil and repaired for 7 days, the fixing rate of Cd reaches 87.5-96%, the fixing rate of Pb reaches 91.8-96.4%, the fixing rate of Zn reaches 87.4-93.4%, the fixing rate of As reaches 61.5-95.3%, and the fixing rate of Sb reaches 70.3-84.96%. After the material for heavy metal mineralization is added into the simulated heavy metal and metalloid ion wastewater (a mixed solution of Cd, Pb, Cu, Zn, Ni, As and Sb, and the concentration of the heavy metal and metalloid ions is 50 mg / L, and the pH is 5.0), the fixing rate of Cd is more than 99.9%, the fixing rate of Pb is more than 99.9%, the fixing rate of Cu reaches 95.32-97.96%, the fixing rate of Zn reaches 96.44-98.18%, the fixing rate of Ni is more than 99.9%, the fixing rate of As reaches 93.92-98.04%, and the fixing rate of Sb reaches 95.12-98.26%, so the material has a good heavy metal repairing effect. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1Process flow chart for preparing the material for heavy metal mineralization for the embodiment of the present application;

[0022] Figure 2 SEM image of the material for heavy metal mineralization prepared for the embodiment 1 of the present application;

[0023] Figure 3 SEM image of the material for heavy metal mineralization prepared for the embodiment 2 of the present application;

[0024] Figure 4 SEM image of the material for heavy metal mineralization prepared for the embodiment 3 of the present application;

[0025] Figure 5 SEM image of the material for heavy metal mineralization prepared for the embodiment 9 of the present application;

[0026] Figure 6 XRD image of the material for heavy metal mineralization prepared for the embodiment 1 of the present application after adsorbing Cd and Pb. DETAILED DESCRIPTION

[0027] The present application provides a preparation method of a material for heavy metal mineralization, comprising the following steps:

[0028] (1) mixing a solution of silicate with a hardly soluble phosphate to perform a substitution reaction to obtain a mixed solution;

[0029] (2) mixing the mixed solution obtained in the step (1) with an acid solution to perform a gelation and then drying to obtain the material for heavy metal mineralization.

[0030] The present application mixes a solution of silicate with a hardly soluble phosphate to perform a substitution reaction to obtain a mixed solution.

[0031] In the present application, the concentration of SiO3 2- in the solution of silicate is preferably 0.6-1.2 mol / L, more preferably 0.8-1.0 mol / L. In the present application, the modulus of the silicate is preferably 2.0-3.5, more preferably 3.0. In the present application, the silicate is preferably sodium silicate and / or potassium silicate. The present application limits the modulus of the silicate and the concentration of the solution of silicate to the above range to control the amount of silica gel generated, and meanwhile enables the subsequent material for heavy metal mineralization to have a good pore structure (pore size).

[0032] In the present application, the insoluble phosphate preferably includes one or more of ferric phosphate, ferrous phosphate, calcium phosphate and aluminum phosphate, and more preferably ferric phosphate and / or ferrous phosphate. The present application limits the type of insoluble phosphate to the range in which the surface charge structure of the insoluble phosphate can be utilized to facilitate adsorption of heavy metals, and the insoluble phosphate precipitates in solution and is difficult to crystallize, thereby maintaining an amorphous state and improving the activity of the material.

[0033] As an embodiment of the present application, the ratio of the amount of substance of phosphorus in the insoluble phosphate to the amount of substance of silicate can be (0.1-2):(0.6-1.2), (0.2-1.5):(0.8-1.0), or (0.3-1.0):0.8. The present application limits the ratio of the amount of substance of phosphorus in the insoluble phosphate to the volume of the solution of silicate to the range in which the SiO3 2- Substitution of the insoluble phosphate facilitates release of the phosphate group in the insoluble phosphate, and also enables the subsequent material for heavy metal mineralization to have a good specific surface area.

[0034] The present application does not have special limitations on the mixing method and operation, and any mixing operation known to those skilled in the art can be used.

[0035] In the present application, the temperature of the substitution reaction is preferably 5-50°C, more preferably 15-40°C, and further preferably 20-25°C; and the time of the substitution reaction is preferably 1-4h, and more preferably 2-3h. The present application limits the temperature and time of the substitution reaction to the range in which the reaction can be ensured to proceed sufficiently.

[0036] In the present application, the substitution reaction is preferably performed under stirring; and the stirring rate is preferably 200-500r / min, and more preferably 250-350r / min. The present application limits the stirring rate to the range in which the reaction can be ensured to proceed more sufficiently.

[0037] In the present application, taking ferric phosphate as an example of the insoluble phosphate, the chemical reaction equation during the substitution reaction is as follows:

[0038] FePO4+2(1-x)OH - +(1-x)H2O=Fe(PO4) x OH 3(1-x) +(1-x)HPO4 2-

[0039] FePO4+SiO3 2- +2H2O=Fe(OH)3+SiO2+HPO4 2-

[0040] After obtaining the mixed solution, the present application mixes the mixed solution with an acid solution, gels after drying to obtain a material for heavy metal mineralization.

[0041] The present application does not have special limitations on the mixing method and operation of the mixed solution and the acid solution, and the mixing operation known to those skilled in the art can be used.

[0042] In the present application, the acid solution preferably includes an inorganic acid solution and / or a dihydrogen phosphate solution; the inorganic acid solution preferably includes one or more of a sulfuric acid solution, a nitric acid solution, a hydrochloric acid solution, and a phosphoric acid solution; and the dihydrogen phosphate solution is preferably a sodium dihydrogen phosphate solution. The present application limits the type of acid solution to the above range to achieve the adjustment of the pH of the mixed solution.

[0043] In the present application, the acid solution functions to adjust the pH of the mixed solution. The present application does not have special limitations on the amount of the acid solution added, and the pH of the mixed solution can be adjusted to 7-10.5. In a specific embodiment of the present application, the concentration of the acid solution is 1 mol / L.

[0044] In the present application, the pH of the gel is preferably 7-10.5, and more preferably 8.5-10. The present application limits the pH of the gel to the above range to obtain a gel.

[0045] In the present application, the chemical reaction equation during the gelation is:

[0046] SiO3 2- +2H + +H2O=H4SiO4

[0047] In the present application, the drying temperature is preferably 15-300°C, and more preferably 50-150°C. The present application does not have special limitations on the drying time, and drying to a constant weight is sufficient. The present application removes the water in the product after gelation by drying, and at the same time, the material for heavy metal mineralization becomes a porous structure, providing more active sites for the attachment of heavy metals.

[0048] The present application further includes grinding after the drying is completed. The present application does not have special requirements for the grinding method, and the grinding method known to those skilled in the art can be used to grind the large pieces into a powder. In a specific embodiment of the present application, the particle size of the powder after grinding is 200 mesh.

[0049] The present application mixes the solution of silicate with the poorly soluble phosphate to react, so that SiO3 2- 、OH - of the solution of silicate reacts with PO4 3-Substitution is carried out to make the phosphate in the insoluble phosphate enter the solution to generate polyhydroxy phosphate, and OH - Metal hydroxide can also be formed with the metal in the insoluble phosphate, the release of the phosphate in the insoluble phosphate is promoted by the substitution reaction, the reactivity of the material in use is greatly improved, the material can slowly release the phosphate and hydrogen phosphate in use, the heavy metal ions are complexed with the phosphate and groups thereof to form stable metal-phosphate minerals on the surface of the material; the generation of the phosphorus-containing wastewater can be effectively prevented by the gelation by adding an acidic solution; the material for heavy metal mineralization is changed into a porous structure by drying, more active sites are provided for the attachment of the heavy metal, the surface of the material contains a large amount of Si-OH and -OH groups due to the addition of the silicate and the substitution reaction, the heavy metal ions can be combined on the surface of the material by deprotonation to form an inner coordination compound, and the heavy metal is fixed, and the silicon-oxygen network structure in the silicic acid formed after the gelation also realizes the controlled release of the phosphorus in use.

[0050] The application further provides the material for heavy metal mineralization prepared by the preparation method.

[0051] In the application, the pore size of the material for heavy metal mineralization is preferably 3-15 nm, and more preferably 4-10 nm; the specific surface area of the material for heavy metal mineralization is preferably 40-200 m 2 / g, and more preferably 50-100 m 2 / g; and the unit mass volume of the material for heavy metal mineralization is preferably 0.15-0.5 cm 3 / g, and more preferably 0.3-0.5 cm 3 / g. The control of the pore size, the specific surface area and the unit mass volume in the above range can facilitate the transportation and the adsorption of the heavy metal and the release of the phosphorus.

[0052] The application further provides the application of the material for heavy metal mineralization in adsorbing heavy metal and / or metalloid ions.

[0053] As an embodiment of the application, the heavy metal ions include one or more of Cd, Pb, Cu, Zn and Ni; and the metalloid ions include As and / or Sb.

[0054] As an embodiment of the application, the application of the material for heavy metal mineralization in adsorbing heavy metal and / or metalloid ions can be the repair of the heavy metal and / or metalloid ion contaminated soil or the heavy metal and / or metalloid ion contaminated water by the material for heavy metal mineralization.

[0055] In the present application, the method for repairing heavy metal and / or metalloid ion contaminated soil or heavy metal and / or metalloid ion contaminated water by using the material for heavy metal mineralization comprises: mixing the material for heavy metal mineralization with the heavy metal and / or metalloid ion contaminated soil or the heavy metal and / or metalloid ion contaminated water for repairing.

[0056] As an embodiment of the present application, when repairing heavy metal and / or metalloid ion contaminated soil, the mass of the material for heavy metal mineralization can be 0.1-3% of the heavy metal / metalloid ion contaminated soil, and can also be 0.2%-1%; the repairing temperature can be 5-40°C, and can also be 15-30°C; the repairing time can be 7-60 days, and can also be 20-30 days.

[0057] As an embodiment of the present application, when repairing heavy metal and / or metalloid ion contaminated water, the dosage of the material for heavy metal mineralization in the heavy metal and / or metalloid ion contaminated water can be 0.1-5 g / L, and can also be 0.5-3 g / L; the repairing temperature can be 5-40°C, and can also be 15-30°C; the repairing time can be 2-48 h, and can also be 4-24 h.

[0058] In the specific embodiments of the present application, the preparation flow chart of the material for heavy metal mineralization is as shown in Figure 1

[0059] The solution of silicate (silicate solution) is mixed with the insoluble phosphate under stirring, and then an acidic solution (acidic reagent) is added to perform gelation under stirring, followed by drying and grinding to obtain the material for heavy metal mineralization.

[0060] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0061] Embodiment 1

[0062] A preparation method of a material for heavy metal mineralization:

[0063] (1) The solution of sodium silicate is mixed with iron phosphate at a temperature of 22°C and a stirring speed of 300 r / min for 1 h to perform a substitution reaction, to obtain a mixed solution; the modulus of the sodium silicate is 3.0; the concentration of SiO3 2- in the solution of sodium silicate is 0.8 mol / L; the molar ratio of phosphorus in the iron phosphate to the sodium silicate is 0.1:0.8.​

[0064] (2) The mixture obtained in step (1) is mixed with a 1 mol / L phosphoric acid solution, gelled by adjusting the pH to 10.0 with the phosphoric acid solution, and dried at 100°C for 24 h, and then ground to 200 mesh to obtain a material for heavy metal mineralization.

[0065] Example 2

[0066] Example 2 differs from Example 1 only in that the molar ratio of phosphorus element in the ferric phosphate to sodium silicate in step (1) is 0.2:0.8, and the rest is the same as in Example 1.

[0067] Example 3

[0068] Example 3 differs from Example 1 only in that the molar ratio of phosphorus element in the ferric phosphate to sodium silicate in step (1) is 0.3:0.8, and the rest is the same as in Example 1.

[0069] Example 4

[0070] Example 4 differs from Example 1 only in that the modulus of sodium silicate in step (1) is 2.5, and the rest is the same as in Example 1.

[0071] Example 5

[0072] Example 5 differs from Example 1 only in that the pH is adjusted to 8.5 with a phosphoric acid solution in step (2), and the rest is the same as in Example 1.

[0073] Example 6

[0074] A method for preparing a material for heavy metal mineralization:

[0075] (1) A solution of sodium silicate is mixed with ferrous phosphate at a temperature of 22°C and a stirring speed of 300 r / min for 1 h to carry out a substitution reaction, obtaining a mixture; the modulus of the sodium silicate is 3.0; the concentration of SiO3 2- in the solution of sodium silicate is 0.8 mol / L; and the molar ratio of phosphorus element in the ferrous phosphate to sodium silicate is 0.2:0.8;

[0076] (2) The mixture obtained in step (1) is mixed with a 1 mol / L sulfuric acid solution, gelled by adjusting the pH to 10.0 with the sulfuric acid solution, and dried at 100°C for 24 h, and then ground to 200 mesh to obtain a material for heavy metal mineralization.

[0077] Example 7

[0078] Example 7 differs from Example 1 only in that the phosphoric acid solution is replaced with a sodium dihydrogen phosphate solution in step (2), and the rest is the same as in Example 1.

[0079] Example 8

[0080] Example 8 is different from Example 1 only in that the stirring speed in the step (1) is 400 r / min, and the others are the same as Example 1.

[0081] Example 9

[0082] Example 9 is different from Example 1 only in that the solution of sodium silicate in the step (1) is replaced by the solution of potassium silicate, and the others are the same as Example 1.

[0083] Comparative Example 1

[0084] Comparative Example 1 is different from Example 9 only in that the acidic solution is not added in the step (2), and the others are the same as Example 9.

[0085] Comparative Example 2

[0086] Comparative Example 2 is different from Example 9 only in that the insoluble phosphate is not added in the step (1), and the others are the same as Example 9.

[0087] Comparative Example 3

[0088] Comparative Example 3 is different from Example 9 only in that the solution of potassium silicate in the step (1) is replaced by the solution of sodium hydroxide with a concentration of 1 mol / L, and the others are the same as Example 9.

[0089] The microstructure of the heavy metal mineralization material prepared in Examples 1-3 and Example 9 is observed by using an electron scanning microscope, and the obtained SEM images are shown in Figures 2 to 5 It can be seen from Figures 2 to 5 that the material for heavy metal mineralization prepared in the application is a cluster formed by the aggregation of particles with loose and porous surfaces.

[0090] A solution of Cd(II) and Pb(II) with a concentration of 500 mg / L is configured, the pH of the solution is adjusted to 5.0, the material for heavy metal mineralization prepared in Example 1 is added into the solution at a concentration of 1 g / L, and after stirring at room temperature for 4 h, the solution is filtered, and the phase of the material for heavy metal mineralization prepared in Example 1 after adsorbing Cd and Pb is analyzed by using an X-ray diffractometer, and the obtained XRD image is shown in Figure 6 It can be seen from Figure 6 that the heavy metal mineralization material of the application can form stable metal-phosphate minerals with heavy metals, and can promote the mineralization of heavy metals.

[0091] Application Examples 1-9

[0092] The material for heavy metal mineralization prepared in Examples 1-9 is mixed with heavy metal and metalloid ion contaminated soil for remediation; the mass of the material for heavy metal mineralization is 1% of the heavy metal and metalloid ion contaminated soil; the remediation temperature is 16°C, and the remediation time is 7 days.

[0093] The soil moisture content is maintained at 30% during the remediation process.

[0094] The heavy metal and / or metalloid ion contaminated soil is collected from a heavy metal contaminated farmland soil in Hunan, dried naturally, and then sieved through a 2mm sieve after removing stones and plant residues.

[0095] Comparative Examples 1-3

[0096] The heavy metal mineralization material prepared in Comparative Examples 1-3 is mixed with heavy metal and metalloid ion contaminated soil for remediation, and the remediation method is the same as in Application Example 1.

[0097] The effective content of heavy metals and metalloids in the soil before and 7 days after remediation in Application Examples 1-9 and Comparative Examples 1-3 is determined, and the testing method is as follows: DTPA-CaCl2-TEA (HJ804-2016) solution is used to extract the effective Cd, Pb and Zn, and 0.5mol / L NaHCO3 solution is used to extract the effective As and Sb.

[0098] The effective content of heavy metals and metalloids before and after remediation is shown in Table 1.

[0099] Table 1: Effective content of heavy metal and metalloid contaminated soil

[0100]

[0101] Application Examples 10-18

[0102] The heavy metal mineralization material prepared in Examples 1-9 is mixed with heavy metal and metalloid ion contaminated water for remediation; the dosage of the material for heavy metal mineralization in the heavy metal and metalloid ion contaminated water is 1g / L; the remediation temperature is 16°C, and the remediation time is 4h.

[0103] The stirring is maintained during the remediation process.

[0104] The heavy metal and metalloid ion contaminated water is simulated heavy metal and metalloid wastewater, and is specifically configured as a mixed solution of Cd(II), Pb(II), Cu(II), Zn(II), Ni(II), As(III / V) and Sb(III / V), wherein the concentrations of Cd(II), Pb(II), Cu(II), Zn(II) and Ni(II) are all 50 mg / L, and the concentrations of As(III / V) and Sb(III / V) are both 10 mg / L, and the pH of the solution is adjusted to 5.0.

[0105] Comparative examples 4-6

[0106] The heavy metal mineralization material prepared in Comparative Examples 1-3 is mixed with the heavy metal and metalloid ion contaminated water for remediation, and the remediation method is the same as that in Application Example 1.

[0107] After the remediation, the heavy metal mineralization material is filtered, and the concentrations of heavy metals and metalloids in the solution are detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0108] The concentrations of heavy metals and metalloids in water before and after remediation are shown in Table 2.

[0109] Table 2 Statistics of concentrations of heavy metals and metalloids in heavy metal and metalloid contaminated water

[0110]

[0111] As shown in Tables 1 and 2, the heavy metal mineralization material prepared by the method provided by the application can simultaneously remediate soil and water contaminated by multiple heavy metals and metalloid ions. According to Application Examples 1-18, the heavy metal mineralization material prepared by the method provided by the application is added to contaminated soil, and after 7 days of remediation, the fixation rate of Cd is 87.5-96%, the fixation rate of Pb is 91.8-96.4%, the fixation rate of Zn is 87.4-93.4%, the fixation rate of As is 61.5-95.3%, and the fixation rate of Sb is 70.3-84.96%; the heavy metal mineralization material is added to simulated heavy metal and metalloid ion wastewater (mixed solution of Cd, Pb, Cu, Zn, Ni, As and Sb, with a concentration of 50 mg / L for each heavy metal and metalloid, and a pH of 5.0), and the fixation rate of Cd is more than 99.9%, the fixation rate of Pb is more than 99.9%, the fixation rate of Cu is 95.32-97.96%, the fixation rate of Zn is 96.44-98.18%, the fixation rate of Ni is more than 99.9%, the fixation rate of As is 93.92-98.04%, and the fixation rate of Sb is 95.12-98.26%, which has a good heavy metal remediation effect.

[0112] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A method for preparing a material for heavy metal mineralization, comprising the following steps: (1) mixing a solution of silicate with a sparingly soluble phosphate to carry out a substitution reaction, to obtain a mixed solution; the silicate is sodium silicate and / or potassium silicate; (2) mixing the mixed solution obtained in step (1) with an acidic solution to carry out gelation, and then drying, to obtain a material for heavy metal mineralization; The concentration of SiO3 in the solution of silicate in step (1) is 0.6-1.2 mol / L. 2- ​ the modulus of the silicate in step (1) is 2.0-3.5; the ratio of the amount of substance of phosphorus in the sparingly soluble phosphate to that of the silicate in step (1) is (0.1-2):(0.6-1.2); the sparingly soluble phosphate in step (1) comprises one or more of ferric phosphate, ferrous phosphate, calcium phosphate and aluminum phosphate; the acidic solution in step (2) comprises an inorganic acid solution and / or a dihydrogen phosphate solution; the inorganic acid solution comprises one or more of sulfuric acid solution, nitric acid solution, hydrochloric acid solution and phosphoric acid solution.

2. The production method according to claim 1, characterized by, the temperature of the substitution reaction in step (1) is 5-50℃, and the time of the substitution reaction is 1-4h.

3. The preparation method according to claim 1, characterized in that, the pH value of the gelation in step (2) is 7-10.

5.

4. The material for heavy metal mineralization produced by the production method according to any one of claims 1 to 3, characterized in that, the chemical composition of the material for heavy metal mineralization comprises phosphate compounds, iron hydroxides, polyhydroxy ferric phosphate, silicon dioxide and silicic acid.

5. Use of the material for heavy metal mineralization according to claim 4 in adsorbing heavy metal and / or metalloid ions.

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