Material for heavy metal mineralization as well as preparation method and application thereof

Abstract

The invention provides a material for heavy metal mineralization as well as 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 provided by the invention comprises the following steps: mixing a silicate solution with insoluble phosphate for substitution reaction to obtain a mixed solution; and mixing the mixed solution with an acidic solution, gelatinizing, and drying to obtain the material for heavy metal mineralization. According to the invention, the silicate solution and the insoluble phosphate are mixed for reaction, so that phosphate radicals in the insoluble phosphate enter the solution, and the reactivity of the material in the use process is improved; the acid solution is added for gelling, so that phosphorus-containing wastewater can be effectively prevented from being generated; the material is changed into a porous structure through drying, more active sites are provided for heavy metal attachment, and then heavy metal is better fixed. The result of the embodiment shows that the prepared material for heavy metal mineralization has a good heavy metal repairing effect.

Description

Technical Field

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

[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 as the above heavy metal elements. After heavy metals contaminate the soil, they cannot be biodegraded and can accumulate through the food chain, seriously endangering ecological environment safety and green economic development. Moreover, heavy metals are cumulative and highly toxic. Long-term exposure to heavy metals can cause adverse effects such as osteomalacia, lung cancer and kidney damage. Therefore, heavy metal and metalloid pollution has become an environmental problem that urgently needs to be solved.

[0003] Stabilization remediation technology has been widely used to repair heavy metal contaminated soil. Stabilization remediation technology is a remediation technology that forms stable chemical bonds with heavy metals by adding remediation materials to reduce the mobility of heavy metals. Among them, the use of phosphate remediation materials to stabilize soil heavy metals is a remediation method that has been widely studied and has great application prospects. Phosphate remediation materials can not only improve soil fertility, but also form stable metal-phosphate compounds with heavy metals to stabilize soil heavy metals. However, current phosphate remediation materials are prone to produce phosphorus-containing wastewater during the preparation process, and most phosphate remediation materials have low reaction activity and low adsorption capacity. When treating heavy metal contaminated soil, the amount of materials used is large and the social and economic benefits are low.

[0004] In related studies, acid-activated red mud, polyphosphate bacteria, phosphorus-containing wastewater and culture medium were mixed and cultured to prepare heavy metal adsorption materials, but the adsorption capacity of the prepared phosphorus-containing materials was low, and after solid-liquid separation, the wastewater still contained a certain amount of phosphorus; there are also related studies that prepared a multi-metal synchronous stabilization functional material by adjusting the ratio of Fe, Mn, and P. The preparation process is simple, but the wastewater contains a large amount of phosphate and hydrogen phosphate; there are also related studies that used microorganisms to modify phosphorus-containing ores to prepare heavy metal passivators, which solved the problem of phosphorus tailings accumulation, but failed to form stable minerals with soil heavy metals, and there is still a risk of secondary release of heavy metals. Summary of the invention

[0005] The object of the present invention is to provide a material for heavy metal mineralization and a preparation method and application thereof. The preparation method provided by the present invention does not generate phosphorus-containing wastewater and secondary pollution during the preparation process, and the prepared material for heavy metal mineralization can form phosphate minerals with heavy metals and has a good heavy metal remediation effect.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a material for heavy metal mineralization, comprising the following steps:

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

[0009] (2) The mixed solution obtained in step (1) is mixed with an acidic solution, gelled and then dried to obtain a material for heavy metal mineralization.

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

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

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

[0013] Preferably, the sparingly soluble phosphate in 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 step (1) is 5 to 50° C., and the time of the substitution reaction is 1 to 4 hours.

[0015] Preferably, 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 a sulfuric acid solution, a nitric acid solution, a hydrochloric acid solution and a phosphoric acid solution.

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

[0017] The present invention also provides a material for heavy metal mineralization prepared by the preparation method described in the above technical solution, wherein the chemical composition of the material for heavy metal mineralization includes phosphate compounds, iron hydroxide, polyhydroxy iron phosphate, silicon dioxide and silicic acid.

[0018] The present invention also provides the use of the material for heavy metal mineralization described in the above technical solution in the adsorption of heavy metal and / or metalloid ions.

[0019] The present invention provides a method for preparing a material for heavy metal mineralization, comprising the following steps: (1) mixing a silicate solution with a sparingly soluble phosphate for substitution reaction to obtain a mixed solution; (2) mixing the mixed solution obtained in step (1) with an acidic solution for gelation and then drying to obtain a material for heavy metal mineralization. The present invention mixes a silicate solution with a sparingly soluble phosphate for reaction to reduce SiO3 in the silicate solution to 1.5 mol / L. 2- OH - For PO4 in insoluble phosphate 3- Replacement is carried out to make the phosphate in the insoluble phosphate enter the solution to form polyhydroxy phosphate. - It can also form metal hydroxides with metals in insoluble phosphates. The substitution reaction promotes the release of phosphates in insoluble phosphates, greatly improving the reactivity of the material during use, allowing the material to slowly release phosphates and hydrogen phosphates during use. Heavy metal ions are complexed with phosphates and their groups to form stable metal-phosphate minerals on the surface of the material. The addition of an acidic solution for gelation can effectively prevent the generation of phosphorus-containing wastewater. The material used for heavy metal mineralization is transformed into a porous structure by drying, providing more active sites for heavy metal attachment. The addition of silicates and the substitution reaction cause the material surface to contain a large number of Si-OH and -OH groups. Heavy metal ions can be combined with the material surface through a deprotonation reaction to form an inner layer complex, thereby fixing the heavy metal. At the same time, the silicon-oxygen network structure in the silicate formed after gelation also realizes the controllable release of phosphorus during the use of the material.

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

[0021] Figure 1A process flow chart for preparing materials for heavy metal mineralization according to an embodiment of the present invention;

[0022] Figure 2 This is a SEM image of the material for heavy metal mineralization prepared in Example 1 of the present invention;

[0023] Figure 3 This is a SEM image of the material for heavy metal mineralization prepared in Example 2 of the present invention;

[0024] Figure 4 This is a SEM image of the material for heavy metal mineralization prepared in Example 3 of the present invention;

[0025] Figure 5 This is a SEM image of the material for heavy metal mineralization prepared in Example 9 of the present invention;

[0026] Figure 6 This is the XRD diagram of the material for heavy metal mineralization prepared in Example 1 of the present invention after adsorbing Cd and Pb. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing a material for heavy metal mineralization, comprising the following steps:

[0028] (1) mixing a silicate solution with a sparingly soluble phosphate to carry out a substitution reaction to obtain a mixed solution;

[0029] (2) The mixed solution obtained in step (1) is mixed with an acidic solution, gelled and then dried to obtain a material for heavy metal mineralization.

[0030] The present invention mixes a silicate solution with a sparingly soluble phosphate to carry out a substitution reaction to obtain a mixed solution.

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

[0032] In the present invention, the sparingly soluble 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 invention limits the types of sparingly soluble phosphates to the above range, and can utilize the rich surface charge structure of sparingly soluble phosphates to facilitate the adsorption of heavy metals, and can also utilize the difficulty of crystallization of sparingly soluble phosphate precipitation in the solution, and improve the activity of the material by maintaining an amorphous state.

[0033] As an embodiment of the present invention, the ratio of the amount of phosphorus in the sparingly soluble phosphate to the amount 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 invention limits the ratio of the amount of phosphorus in the sparingly soluble phosphate to the volume of the silicate solution to the above range, which can promote the formation of SiO3 2- The replacement of sparingly soluble phosphates is beneficial to the release of phosphate groups in the sparingly soluble phosphates, and can also enable the subsequent materials used for heavy metal mineralization to have a good specific surface area.

[0034] The present invention has no special limitation on the mixing method and operation, and the mixing operation well known to those skilled in the art can be used.

[0035] In the present invention, the temperature of the substitution reaction is preferably 5 to 50° C., more preferably 15 to 40° C., and further preferably 20 to 25° C.; the time of the substitution reaction is preferably 1 to 4 hours, and more preferably 2 to 3 hours. The present invention limits the temperature and time of the substitution reaction to the above ranges to ensure that the reaction proceeds fully.

[0036] In the present invention, the substitution reaction is preferably carried out under stirring conditions; the stirring rate is preferably 200-500 r / min, more preferably 250-350 r / min. The present invention limits the stirring rate to the above range to ensure that the reaction proceeds more fully.

[0037] In the present invention, taking the insoluble phosphate as iron phosphate as an example, the chemical reaction equation in the substitution reaction process is:

[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 invention mixes the mixed solution with an acidic solution for gelation and then dries to obtain a material for heavy metal mineralization.

[0041] The present invention has no particular limitation on the mixing method and operation of the mixed solution and the acidic solution, and the mixing operation well known to those skilled in the art can be used.

[0042] In the present invention, the acidic 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; the dihydrogen phosphate solution is preferably a sodium dihydrogen phosphate solution. The present invention limits the type of acidic solution to the above range so that the pH of the mixed solution can be adjusted.

[0043] In the present invention, the acidic solution is used to adjust the pH value of the mixed solution. The present invention has no particular limitation on the amount of the acidic solution added, and the acidic solution can be used to adjust the pH value of the mixed solution to 7 to 10.5. In a specific embodiment of the present invention, the concentration of the acidic solution is 1 mol / L.

[0044] In the present invention, the pH value of the gelation is preferably 7 to 10.5, and more preferably 8.5 to 10. In the present invention, the gel can be obtained by limiting the pH of the gelation to the above range.

[0045] In the present invention, the chemical reaction equation in the gelation process is:

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

[0047] In the present invention, the drying temperature is preferably 15 to 300° C., more preferably 50 to 150° C. The present invention has no particular limitation on the drying time, and drying to constant weight is sufficient. The present invention removes moisture from the gelled product by drying, and at the same time, the material used for heavy metal mineralization becomes a porous structure, providing more active sites for heavy metal attachment.

[0048] The present invention further comprises grinding after drying; the present invention has no special requirements on the grinding method, and the bulk material can be ground into powder using a grinding method well known to those skilled in the art. In a specific embodiment of the present invention, the particle size of the powder after grinding is 200 meshes.

[0049] The present invention mixes a silicate solution with a sparingly soluble phosphate to react, so that SiO3 in the silicate solution 2- OH - For PO4 in insoluble phosphate 3-Replacement is carried out to make the phosphate in the insoluble phosphate enter the solution to form polyhydroxy phosphate. - It can also form metal hydroxides with metals in insoluble phosphates. The substitution reaction promotes the release of phosphates in insoluble phosphates, greatly improving the reactivity of the material during use, allowing the material to slowly release phosphates and hydrogen phosphates during use. Heavy metal ions are complexed with phosphates and their groups to form stable metal-phosphate minerals on the surface of the material. The addition of an acidic solution for gelation can effectively prevent the generation of phosphorus-containing wastewater. The material used for heavy metal mineralization is transformed into a porous structure by drying, providing more active sites for heavy metal attachment. The addition of silicates and the substitution reaction cause the material surface to contain a large number of Si-OH and -OH groups. Heavy metal ions can be combined with the material surface through a deprotonation reaction to form an inner layer complex, thereby fixing the heavy metal. At the same time, the silicon-oxygen network structure in the silicate formed after gelation also realizes the controllable release of phosphorus during the use of the material.

[0050] The present invention also provides a material for heavy metal mineralization prepared by the preparation method described in the above technical solution, wherein the chemical composition of the material for heavy metal mineralization includes phosphate compounds, iron hydroxide, polyhydroxy iron phosphate, silicon dioxide and silicic acid.

[0051] In the present invention, the pore size of the material for heavy metal mineralization is preferably 3 to 15 nm, more preferably 4 to 10 nm; the specific surface area of ​​the material for heavy metal mineralization is preferably 40 to 200 m 2 / g, more preferably 50 to 100 m 2 / g; the unit mass volume of the material used for heavy metal mineralization is preferably 0.15 to 0.5 cm 3 / g, more preferably 0.3 to 0.5 cm 3 The present invention controls the pore size, specific surface area and unit mass volume within the above ranges, which can facilitate transportation while being beneficial to the adsorption of heavy metals and the release of phosphorus.

[0052] The present invention also provides the use of the material for heavy metal mineralization described in the above technical solution in the adsorption of heavy metal and / or metalloid ions.

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

[0054] As an embodiment of the present invention, the use of the material for heavy metal mineralization in the adsorption of heavy metal and / or metalloid ions can be used as a material for heavy metal mineralization to repair soil contaminated by heavy metals and / or metalloid ions or water contaminated by heavy metals and / or metalloid ions.

[0055] In the present invention, the method for repairing soil contaminated by heavy metals and / or metalloid ions or water contaminated by heavy metals and / or metalloid ions using materials for heavy metal mineralization comprises: mixing the materials for heavy metal mineralization with soil contaminated by heavy metals and / or metalloid ions or water contaminated by heavy metals and / or metalloid ions for repair.

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

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

[0058] In a specific embodiment of the present invention, the preparation flow chart of the material for heavy metal mineralization is as follows: Figure 1 As shown:

[0059] A silicate solution (silicate solution) and a sparingly soluble phosphate are stirred and mixed, and then an acidic solution (acidic reagent) is added to gel under stirring conditions, followed by drying and grinding to obtain a material for heavy metal mineralization.

[0060] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] Example 1

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

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

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

[0065] Example 2

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

[0067] Example 3

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

[0069] Example 4

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

[0071] Example 5

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

[0073] Example 6

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

[0075] (1) Mixing a sodium silicate solution with ferrous phosphate at a temperature of 22° C. and a stirring speed of 300 r / min for a substitution reaction for 1 hour to obtain a mixed solution; the modulus of the sodium silicate is 3.0; the SiO3 in the sodium silicate solution is 2- The concentration is 0.8 mol / L; the molar ratio of phosphorus in ferrous phosphate to sodium silicate is 0.2:0.8;

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

[0077] Example 7

[0078] The difference between Example 7 and Example 1 is that the phosphoric acid solution is replaced by sodium dihydrogen phosphate solution in step (2), and the rest is the same as Example 1.

[0079] Example 8

[0080] The only difference between Example 8 and Example 1 is that the stirring speed in step (1) is 400 r / min, and the rest is the same as Example 1.

[0081] Example 9

[0082] The only difference between Example 9 and Example 1 is that in step (1), the sodium silicate solution is replaced by a potassium silicate solution, and the rest is the same as Example 1.

[0083] Comparative Example 1

[0084] The difference between Comparative Example 1 and Example 9 is that no acidic solution is added in step (2), and the rest is the same as Example 9.

[0085] Comparative Example 2

[0086] The difference between Comparative Example 2 and Example 9 is that in step (1), no sparingly soluble phosphate is added, and the rest is the same as Example 9.

[0087] Comparative Example 3

[0088] The difference between Comparative Example 3 and Example 9 is that in step (1), the potassium silicate solution is replaced with a 1 mol / L sodium hydroxide solution, and the rest is the same as Example 9.

[0089] The microstructures of the heavy metal mineralized materials prepared in Examples 1 to 3 and Example 9 were observed using an electron scanning microscope, and the obtained SEM images were as follows: Figures 2 to 5 As shown, from Figures 2 to 5 It can be seen that the material for heavy metal mineralization prepared by the present invention is a cluster formed by the aggregation of particles with loose and porous surfaces.

[0090] A 500 mg / L solution of Cd(II) and Pb(II) was prepared, and the pH of the solution was adjusted to 5.0. The material for heavy metal mineralization prepared in Example 1 was added to the solution at 1 g / L, and the solution was stirred for 4 hours at room temperature and then filtered. The material for heavy metal mineralization prepared in Example 1 was subjected to phase analysis after adsorption of Cd and Pb by an X-ray diffractometer. The obtained XRD pattern was as follows: Figure 6 As shown, from Figure 6 It can be seen that the heavy metal mineralization material of the present invention can form stable metal-phosphate minerals with heavy metals, and can promote heavy metal mineralization.

[0091] Application Examples 1 to 9

[0092] The materials for heavy metal mineralization prepared in Examples 1 to 9 were mixed with soil contaminated by heavy metals and metalloid ions for remediation; the mass of the materials for heavy metal mineralization was 1% of the soil contaminated by heavy metals and metalloid ions; the remediation temperature was 16° C. and the remediation time was 7 days.

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

[0094] The heavy metal and / or metalloid ion contaminated soil was collected from a heavy metal contaminated farmland in Hunan Province. After natural air drying, stones and plant residues were removed and the soil was sieved with a 2 mm sieve.

[0095] Comparative Application Examples 1 to 3

[0096] The heavy metal mineralized materials prepared in Comparative Examples 1 to 3 are mixed with soil contaminated by heavy metals and metalloid ions for remediation. The remediation method is the same as that in Application Example 1.

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

[0098] The effective contents of heavy metals and metalloids before and after restoration are shown in Table 1.

[0099] Table 1 Statistics on the effective content of heavy metals and metalloids in soil contaminated by

[0100]

[0101] Application Examples 10-18

[0102] The heavy metal mineralization materials prepared in Examples 1 to 9 were mixed with heavy metal and metalloid ion contaminated water for remediation; the dosage of the heavy metal mineralization materials in the heavy metal and metalloid ion contaminated water was 1 g / L; the remediation temperature was 16°C and the remediation time was 4 hours.

[0103] Stirring was maintained during the repair process.

[0104] The heavy metal and metalloid ion contaminated water is simulated heavy metal and metalloid wastewater, and the specific configuration is: 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, the concentrations of As(III / V) and Sb(III / V) are all 10 mg / L, and the pH of the solution is adjusted to 5.0.

[0105] Comparative Application Examples 4 to 6

[0106] The heavy metal mineralized materials prepared in Comparative Examples 1 to 3 are mixed with heavy metal and metalloid ion contaminated water for repair. The repair method is the same as that in Application Example 1.

[0107] After the remediation, the heavy metal mineralized materials were filtered, and the concentrations of heavy metals and metalloids in the solution were detected using inductively coupled plasma mass spectrometry (ICP-MS).

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

[0109] Table 2 Statistics of heavy metal and metalloid concentrations in heavy metal and metalloid polluted water

[0110]

[0111] It can be concluded from Tables 1 and 2 that the material for heavy metal mineralization prepared by the present invention can simultaneously repair soil and water contaminated by multiple heavy metals and metalloid ions. According to Application Examples 1 to 18, the material for heavy metal mineralization prepared by the preparation method provided by the present invention is added to the contaminated soil. After 7 days of repair, the fixation rate of Cd reaches 87.5-96%, the fixation rate of Pb reaches 91.8-96.4%, the fixation rate of Zn reaches 87.4-93.4%, the fixation rate of As reaches 61.5-95.3%, and the fixation rate of Sb reaches 70.3-84.96%; the material for heavy metal mineralization is added to the model In the simulated heavy metal and metalloid ion wastewater (mixed solution of Cd, Pb, Cu, Zn, Ni, As, Sb, heavy metal and metalloid concentrations are 50 mg / L, pH is 5.0), the fixation rate of Cd is over 99.9%, the fixation rate of Pb is over 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 over 99.9%, the fixation rate of As is 93.92-98.04%, and the fixation rate of Sb is 95.12-98.26%, with good heavy metal remediation effect.

[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a material for heavy metal mineralization, comprising the following steps: (1) mixing a silicate solution with a sparingly soluble phosphate to carry out a substitution reaction to obtain a mixed solution; (2) The mixed solution obtained in step (1) is mixed with an acidic solution, gelled and then dried to obtain a material for heavy metal mineralization.

2. The preparation method according to claim 1, characterized in that: In the step (1), SiO3 in the silicate solution 2- The concentration is 0.6~1.2mol / L.

3. The preparation method according to claim 1 or 2, characterized in that: The modulus of the silicate in step (1) is 2.0 to 3.

5.

4. The preparation method according to claim 1, characterized in that: In the step (1), the molar ratio of phosphorus element in the sparingly soluble phosphate to silicate is (0.1-2): (0.6-1.2).

5. The preparation method according to claim 1 or 4, characterized in that: The sparingly soluble phosphate in step (1) includes one or more of ferric phosphate, ferrous phosphate, calcium phosphate and aluminum phosphate.

6. The preparation method according to claim 1 or 4, characterized in that: The temperature of the substitution reaction in step (1) is 5 to 50° C., and the time of the substitution reaction is 1 to 4 hours.

7. The preparation method according to claim 1, characterized in that: The acidic solution in step (2) includes an inorganic acid solution and / or a dihydrogen phosphate solution; the inorganic acid solution includes one or more of a sulfuric acid solution, a nitric acid solution, a hydrochloric acid solution and a phosphoric acid solution.

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

5.

9. The material for heavy metal mineralization prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The chemical composition of the material for heavy metal mineralization includes phosphate compounds, iron hydroxide, polyhydroxy iron phosphate, silicon dioxide and silicic acid.

10. Use of the material for heavy metal mineralization according to claim 9 in the adsorption of heavy metal and / or metalloid ions.

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