A heavy metal pollution repair material and its preparation method and application

Abstract

The present invention provides a heavy metal pollution remediation material and a preparation method and application thereof, belonging to the technical field of soil remediation. The present invention uses trivalent iron to modify phosphate. In the first precipitation, the soluble trivalent iron salt is incompletely precipitated, and a part of the trivalent iron is converted into iron hydroxide; in the second precipitation, the remaining trivalent iron and part or all of the iron hydroxide react with the phosphate to generate fine hydroxy iron phosphate compound particles, and under the solidification effect of water glass, a heavy metal pollution remediation material containing phosphate compounds, iron hydroxides and hydroxy iron phosphate compounds is obtained. The heavy metal pollution remediation material of the present invention is environmentally friendly, loose and porous, has a large specific surface area and abundant surface functional groups, wherein the phosphate group can form a strong complex or precipitation with heavy metal cations, and the surface hydroxyl group of the iron (hydride) oxide has a good affinity for oxygen-containing anions such as As and Sb, and can form a stable complex.

Description

Technical Field

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

[0002] In recent years, many domestic and foreign scholars have conducted extensive research on the problem of heavy metal pollution in soil. Heavy metals refer to metals with atomic density of not less than 4.5 g·cm -3 Metals mainly refer to heavy elements with significant biological toxicity, such as cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), and metalloids arsenic (As), antimony (Sb). When heavy metals enter the soil, over time, when they reach a certain level, they will have toxic effects on animals and plants. Long-term exposure to heavy metals can cause adverse effects such as fractures, lung cancer, and renal insufficiency. At the same time, heavy metals can also directly or indirectly endanger human health through groundwater and surface water. Therefore, heavy metal and metalloid pollution has become an environmental problem that urgently needs to be solved, especially the serious situation of soil contamination by multiple heavy metals and metalloids.

[0003] Compared with other remediation technologies, phosphate materials are a remediation method that has been widely studied and has great application prospects. When applied to the soil, they can not only quickly reduce the migration capacity and bioavailability of heavy metals in the soil, repair the contaminated soil, but also improve soil fertility and increase crop yields. However, unmodified phosphate remediation materials have the problem of unsatisfactory curing effect, and because phosphates and arsenates have similar chemical behaviors in the soil and the compounds formed in the soil are also similar, the two will compete for adsorption sites, and the remediation effect on multi-metal composite pollution systems is not significant.

[0004] Regarding the modification of phosphates, Chinese invention CN114316992A discloses a multi-metal synchronous stabilization functional material, which mainly contains divalent iron salts, trivalent iron salts, divalent manganese salts and phosphates. This patent produces a large amount of phosphorus-containing wastewater during the preparation process, which is easy to cause secondary pollution. Chinese invention CN103275725A discloses a method for preparing a chemical fixative for heavy metal contaminated soil remediation. This patent requires the use of hydrogen peroxide, sodium hypochlorite, sodium chlorate and other oxidants to oxidize Fe 2+ The ions are oxidized, and the production process of this repair agent is cumbersome and complicated, and the cost is high. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a heavy metal pollution remediation material and a preparation method thereof. The preparation method provided by the present invention is simple to operate, does not produce secondary pollution of phosphorus-containing wastewater, and the obtained heavy metal pollution remediation material 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 heavy metal pollution repair material, comprising the following steps:

[0008] Mixing a soluble ferric iron salt, a mineral dispersant and water to obtain an iron salt dispersion;

[0009] Adjusting the pH value of the iron salt dispersion to 1.5-2.5, performing a first precipitation reaction, and obtaining a first precipitation reaction liquid;

[0010] The first precipitation reaction liquid is mixed with a soluble phosphate to perform a second precipitation reaction to obtain a second precipitation reaction liquid;

[0011] The pH value of the second precipitation reaction liquid is adjusted to 7-10 using water glass, and then solidified to obtain a heavy metal pollution repair material.

[0012] Preferably, the soluble ferric iron salt contains Fe 3+ With soluble phosphate PO4 3- The molar ratio is 1:0.4~2.

[0013] Preferably, the mineral dispersant is one or more of sepiolite, white carbon black and kaolin;

[0014] The particle size of the mineral dispersant is 10 to 100 nm;

[0015] The mass of the mineral dispersant is 5-10% of the total mass of the soluble trivalent iron salt and the soluble phosphate.

[0016] Preferably, the temperature of the first precipitation reaction and the second precipitation reaction are independently 15 to 40°C.

[0017] Preferably, the modulus of the water glass is 3.3-4.

[0018] Preferably, the soluble phosphate is added in the form of an aqueous solution, and the mass ratio of the soluble phosphate to water is 1:4.5-6.5.

[0019] Preferably, after the solidification, the obtained solidified material is dried and ground to obtain heavy metal pollution repair material powder, and the particle size of the heavy metal pollution repair material powder is 100 to 300 meshes.

[0020] The present invention provides a heavy metal pollution repair material prepared by the above preparation method, the chemical composition of which includes a phosphate compound, iron hydroxide, a hydroxy iron phosphate compound and water glass;

[0021] The pore size of the heavy metal pollution remediation material is 3 to 15 nm, and the specific surface area is 40 to 150 m 2 / g, total pore volume is 0.15~0.5cm 3 / g.

[0022] The present invention provides the use of the heavy metal pollution remediation material in remediating heavy metal and metalloid polluted soil and / or heavy metal and metalloid polluted water.

[0023] Preferably, the heavy metal includes one or more of Cd, Pb, Cu, and Zn, and the metalloid includes As and / or Sb.

[0024] The present invention provides a preparation method of a heavy metal pollution repair material, comprising the following steps: mixing a soluble trivalent iron salt, a mineral dispersant and water to obtain an iron salt dispersion; adjusting the pH value of the iron salt dispersion to 1.5-2.5, performing a first precipitation reaction, and obtaining a first precipitation reaction liquid; mixing the first precipitation reaction liquid with a soluble phosphate, performing a second precipitation reaction, and obtaining a second precipitation reaction liquid; using water glass to adjust the pH value of the second precipitation reaction liquid to 7-10, and performing solidification to obtain a heavy metal pollution repair material. The present invention uses trivalent iron to modify phosphate. During the first precipitation reaction, the soluble trivalent iron salt is incompletely precipitated, and a portion of the trivalent iron is converted into iron hydroxide; during the second precipitation reaction, the remaining trivalent iron and part or all of the iron hydroxide react with the phosphate to generate fine hydroxy iron phosphate compound particles. Under the solidification effect of water glass, a heavy metal pollution repair material containing phosphate compounds, iron hydroxides and hydroxy iron phosphate compounds is finally obtained. The heavy metal pollution remediation material provided by the present invention is not only environmentally friendly, but also loose and porous, with a large specific surface area and abundant surface functional groups, wherein the phosphate group can form a strong complex or precipitation with heavy metal cations, and the surface hydroxyl group of iron (hydroxide) oxide has a good affinity for oxygen-containing anions such as As and Sb, and can form a stable complex. Therefore, the heavy metal pollution remediation material prepared by the present invention can effectively stabilize a variety of heavy metals (Cd, Pb, Cu, Zn) and metalloids (As, Sb) at the same time, and can effectively repair or purify soil or wastewater with heavy (metal) composite pollution. The present invention can effectively prevent the aggregation of iron (hydroxide) oxides by adding a mineral dispersant, and can increase the negative charge on the surface of the remediation material, and promote the adsorption of heavy metal cations by the remediation material.

[0025] Furthermore, the present invention adjusts the ratio of phosphate and trivalent iron salt so that the prepared heavy metal pollution remediation material can effectively remediate soil or wastewater of different pollution types. Specifically, the PO4 3- When the Fe in the ferric salt is 3+ With PO4 in phosphate3- When the molar ratio of Fe is 1:1-2, the proportion of phosphate compounds in the obtained product is high. Phosphate compounds tend to stabilize Cd, Pb, Cu, and Zn, and can be used to repair soil or wastewater with high content of Cd, Pb, Cu, and Zn. 3+ When the Fe in the ferric salt is 3+ With PO4 in phosphate 3- When the molar ratio is 1:0.4 to 1 (excluding 1:1), the proportion of iron (hydroxide) in the obtained product is high, and iron (hydroxide) tends to stabilize As and Sb, and can be used to repair soil or wastewater with complex pollution with high As and Sb content.

[0026] At the same time, the preparation method provided by the invention is simple to operate, low in cost, and suitable for industrial mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The preparation process of the heavy metal pollution repair material of the present invention;

[0028] Figure 2 These are scanning electron microscope images of the heavy metal pollution remediation materials prepared in Examples 1, 2, 3, and 8. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing a heavy metal pollution repair material, comprising the following steps:

[0030] Mixing a soluble ferric iron salt, a mineral dispersant and water to obtain an iron salt dispersion;

[0031] Adjusting the pH value of the iron salt dispersion to 1.5-2.5, performing a first precipitation reaction, and obtaining a first precipitation reaction liquid;

[0032] The first precipitation reaction liquid is mixed with a soluble phosphate to perform a second precipitation reaction to obtain a second precipitation reaction liquid;

[0033] The pH value of the second precipitation reaction liquid is adjusted to 7-10 using water glass, and then solidified to obtain a heavy metal pollution repair material.

[0034] The present invention mixes a soluble trivalent iron salt, a mineral dispersant and water to obtain an iron salt dispersion. In the present invention, the soluble trivalent iron salt is preferably one or more of Fe2(SO4)3, FeCl3 and NH4Fe(SO4)2. In the present invention, the Fe2(SO4)3 is preferably Fe2(SO4)3·xH2O. The present invention has no special requirements for the value of x, and Fe2(SO4)3·xH2O well known to those skilled in the art can be used.

[0035] In the present invention, the mineral dispersant is preferably one or more of sepiolite, white carbon black and kaolin; the particle size of the mineral dispersant is preferably micrometer-level or nanometer-level. In the present invention, the mass of the mineral dispersant is preferably 5-10% of the total mass of soluble trivalent iron salts and soluble phosphates, and more preferably 5-7%. In the present invention, the mineral dispersant is a natural mineral with a wide range of sources, which is cheap, easy to obtain, environmentally friendly, and has good dispersibility and chemical stability. By adding the mineral dispersant, the present invention can effectively prevent the aggregation of iron (hydroxide) oxides, increase the negative charge on the surface of heavy metal pollution remediation materials, and promote the adsorption of heavy metal cations by heavy metal pollution remediation materials.

[0036] In the present invention, the mass ratio of the soluble iron salt to water is preferably 1:13.5-15, more preferably 1:14-14.5. In the present invention, the mixing temperature is preferably 15-40°C, more preferably room temperature; the time is preferably 15-65min, more preferably 30-40min. In the present invention, the mixing method is preferably stirring mixing, and the stirring mixing rate is preferably 200-500r / min, more preferably 300-400r / min.

[0037] After obtaining the iron salt dispersion, the present invention adjusts the pH value of the iron salt dispersion to 1.5-2.5, performs a first precipitation reaction, and obtains a first precipitation reaction liquid. In the present invention, the reagent used to adjust the pH value is preferably an alkaline reagent, and the alkaline reagent is preferably one or more of NaOH, KOH and ammonia water; in the present invention, the NaOH and KOH are preferably added in the form of NaOH solution and KOH solution.

[0038] In the present invention, the temperature of the first precipitation reaction is preferably 15-40°C, more preferably 25°C; the time of the first precipitation reaction is preferably 5-15 min, more preferably 8-10 min. In the present invention, the first precipitation reaction is preferably carried out under stirring, and the stirring rate is preferably 200-500 r / min, more preferably 300-400 r / min. In the present invention, in the first precipitation reaction, the trivalent iron salt is not completely precipitated as the corresponding hydroxide.

[0039] After obtaining the first precipitation reaction liquid, the present invention mixes the first precipitation reaction liquid with a soluble phosphate to perform a second precipitation reaction to obtain a second precipitation reaction liquid. In the present invention, the soluble phosphate is preferably one or more of NH4H2PO4, (NH4)2HPO4, NaH2PO4, Na2HPO4·12H2O, KH2PO4 and K2HPO4. In the present invention, Fe 3+ With soluble phosphate PO43- The molar ratio of Fe in the trivalent iron salt is preferably 1:0.4-2. 3+ With PO4 in phosphate 3- The molar ratio of phosphate and trivalent iron salt is specifically 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:2. The present invention adjusts the ratio of phosphate and trivalent iron salt so that the prepared heavy metal pollution remediation material can effectively remediate soil or wastewater of different pollution types. Specifically, it increases PO4 3- When the Fe in the ferric salt is 3+ With PO4 in phosphate 3- When the molar ratio of Fe is 1:1 to 2, and is preferably 1:1, 1:1.2, 1:1.5, or 1:2, the proportion of phosphate compounds in the obtained product is high, and phosphate compounds tend to stabilize Cd, Pb, Cu, and Zn, and can be used to repair soil or wastewater with high content of Cd, Pb, Cu, and Zn. 3+ When the Fe in the ferric salt is 3+ With PO4 in phosphate 3- When the molar ratio is 1:0.4 to 1 (excluding 1:1), and specifically preferably 1:0.4, 1:0.6, and 1:0.8, the proportion of iron (hydroxide) in the obtained product is high, and iron (hydroxide) tends to stabilize As and Sb, and can be used to repair soil or wastewater with high As and Sb content.

[0040] In the present invention, the soluble phosphate is preferably added in the form of an aqueous solution, and the mass ratio of the soluble phosphate to water is preferably 1:4.5-6.5, more preferably 1:5-6.

[0041] In the present invention, the mixing temperature is preferably 15-40°C, more preferably room temperature; the mixing time is preferably 15-65 min, more preferably 30-40 min. In the present invention, the mixing method is preferably stirring mixing, and the stirring mixing rate is preferably 200-500 r / min, more preferably 300-400 r / min.

[0042] In the present invention, the temperature of the second precipitation reaction is preferably 15-40°C, more preferably 25°C; the time of the second precipitation reaction is preferably 15-65min, more preferably 30-40min. In the present invention, the second precipitation reaction is preferably carried out under stirring, and the stirring rate is preferably 200-500r / min, more preferably 300-400r / min. In the process of the second precipitation reaction, the trivalent iron salt that has not undergone the first precipitation reaction reacts with the phosphate to form fine iron phosphate compound particles.

[0043] After obtaining the second precipitation reaction liquid, the present invention uses water glass to adjust the pH value of the second precipitation reaction liquid to 7-10, solidifies it, and obtains a heavy metal pollution repair material. In the present invention, the chemical formula of the water glass is preferably Na2O·nSiO2; the modulus of the water glass is preferably 3.3-4, and more preferably 3.5-3.8.

[0044] In the present invention, the curing temperature is preferably 15-40°C, more preferably 20-30°C, and the curing time is preferably 45-60 min, more preferably 50-55 min. In the present invention, during the curing process, with the addition of water glass, the reaction solution gradually becomes viscous and flocculated until it is completely cured.

[0045] After the curing, the present invention also preferably includes drying and grinding the obtained solidified material to obtain heavy metal pollution repair material powder, and the particle size of the heavy metal pollution repair material powder is 100-300 mesh. In the present invention, the drying temperature is preferably 100-300°C, more preferably 100-200°C; the present invention has no special requirements for the drying time, and it can be dried to constant weight.

[0046] The present invention has no special requirements for the grinding method, and a grinding method well known to those skilled in the art can be used. In the present invention, the particle size of the heavy metal pollution remediation material powder is preferably 100 to 300 meshes, more preferably 200 meshes.

[0047] The present invention provides a heavy metal pollution remediation material prepared by the above preparation method, the chemical composition of which includes a phosphate compound, an iron hydroxide and a hydroxy iron phosphate compound; in the present invention, the pore size of the heavy metal pollution remediation material is 3 to 15 nm, preferably 5 to 10 nm; the specific surface area is 40 to 150 m 2 / g, preferably 60 to 100 m 2 / g; total pore volume is 0.15~0.5cm 3 / g, preferably 0.2 to 0.4 cm 3 / g.

[0048] The heavy metal pollution repair material provided by the present invention is not only environmentally friendly, but also loose and porous, with a large specific surface area and abundant surface functional groups. The main chemical components are hydroxyphosphate and iron (hydroxide), and at the same time, it has the stabilization performance of phosphate compounds and iron (hydroxide) oxides to heavy metals or heavy metal-like materials, wherein the phosphate group can form a strong complex or precipitation with heavy metal cations, and the surface hydroxyl group of iron (hydroxide) oxide has a good affinity for oxygen-containing ions such as As and Sb, and can form a stable complex. Therefore, the heavy metal pollution repair material prepared by the present invention can effectively stabilize a variety of heavy metals (Cd, Pb, Cu, Zn) and metalloids (As, Sb) at the same time, and can effectively repair or purify soil or wastewater contaminated by heavy metals and metalloids. The present invention adds a mineral dispersant, which can effectively prevent the aggregation of iron (hydroxide), and can increase the negative charge on the surface of the heavy metal pollution repair material, and promote the adsorption of heavy metal cations by the heavy metal pollution repair material.

[0049] The present invention provides the use of the above-mentioned heavy metal pollution remediation material in remediating heavy metal, metalloid contaminated soil and / or heavy metal, metalloid contaminated water. In the present invention, the heavy metal includes one or more of Cd, Pb, Cu, and Zn, and the metalloid includes As and / or Sb.

[0050] In the present invention, the method for repairing contaminated soil or contaminated water using the metal pollution repair material preferably comprises the following steps:

[0051] Mix metal pollution remediation materials with contaminated soil or contaminated water for remediation.

[0052] In the present invention, when remediating contaminated soil, the mass of the metal pollution remediation material is preferably 0.1-2% of the mass of the contaminated soil, and more preferably 0.5-1.5%; the remediation temperature is preferably 10-40°C, and more preferably 20-30°C; the remediation time is preferably 30-60 days, and more preferably 40-50 days.

[0053] In the present invention, when remediating polluted water, the amount of the metal pollution remediation material added to the wastewater is preferably 0.1-3 g / L, more preferably 0.5-2 g / L. The remediation temperature is preferably 10-40°C, more preferably 20-30°C; the remediation time is preferably 4-36 hours, more preferably 10-30 hours.

[0054] The heavy metal pollution remediation material provided by the present invention, its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0055] Example 1

[0056] The preparation method of heavy metal pollution repair material comprises the following steps:

[0057] (1) The preparation process is carried out at room temperature. The preparation process is as follows Figure 1 As shown; Fe 3+ :PO4 3- Fe2(SO4)3·xH2O and Na2HPO4·12H2O in a molar ratio of 1:0.4 are dissolved in water respectively, 10% of the total mass of iron salt and phosphate white carbon black is added to the ferric sulfate solution, and after stirring evenly, the pH value is adjusted to 2 with a sodium hydroxide solution with a concentration of 1 mol / L, and disodium hydrogen phosphate solution is added to the iron-containing mixed solution, and the mixture is stirred continuously at a speed of 300 r / min with a stirrer;

[0058] (2) After step (1) reacts for 30 minutes, the pH value is adjusted to 8.5 with water glass solution until the solution solidifies into a gelatinous state, and then dried at 100° C. and ground into 200 mesh to obtain a heavy metal pollution remediation material.

[0059] Example 2

[0060] The preparation method of heavy metal pollution repair material comprises the following steps:

[0061] (1) The preparation process is carried out at room temperature. The preparation process is as follows Figure 1 As shown; Fe 3+ :PO4 3- Fe2(SO4)3·xH2O and Na2HPO4·12H2O in a molar ratio of 1:0.6 are fully dissolved in water, and 10% of the total mass of iron salt and phosphate white carbon black is added to the ferric sulfate solution. After stirring evenly, the pH value is adjusted to 2.2 with a sodium hydroxide solution with a concentration of 1 mol / L, and disodium hydrogen phosphate solution is added to the iron-containing mixed solution, and the mixture is continuously stirred at a speed of 300 r / min with a stirrer;

[0062] (2) After step (1) reacts for 30 minutes, the pH value is adjusted to 8.5 with water glass solution until the solution solidifies into a gelatinous state, and then dried at 100° C. and ground into 200 mesh to obtain a heavy metal pollution remediation material.

[0063] Example 3

[0064] The preparation method of heavy metal pollution repair material comprises the following steps:

[0065] (1) The preparation process is carried out at room temperature. The preparation process is as follows Figure 1 As shown; Fe 3+ :PO4 3-Fe2(SO4)3·xH2O and Na2HPO4·12H2O in a molar ratio of 1:0.8 are fully dissolved in water, and 10% of the total mass of iron salt and phosphate white carbon black is added to the ferric sulfate solution. After stirring evenly, the pH value is adjusted to 2.5 with a sodium hydroxide solution with a concentration of 1 mol / L, and disodium hydrogen phosphate solution is added to the iron-containing mixed solution, and the mixture is continuously stirred at a speed of 300 r / min with a stirrer;

[0066] (2) After step (1) reacts for 30 minutes, the pH value is adjusted to 8.5 with water glass solution until the solution solidifies into a gelatinous state, and then dried at 100° C. and ground into 200 mesh to obtain a heavy metal pollution remediation material.

[0067] Example 4

[0068] (1) The preparation process is carried out at room temperature. The preparation process is as follows Figure 1 As shown; Fe 3+ :PO4 3- Fe2(SO4)3·xH2O and Na2HPO4·12H2O in a molar ratio of 1:1 are fully dissolved in water, 10% of the total mass of iron salt and phosphate white carbon black is added to the ferric sulfate solution, and after stirring evenly, the pH value is adjusted to 2 with a sodium hydroxide solution with a concentration of 1 mol / L, and disodium hydrogen phosphate solution is added to the iron-containing mixed solution, and the mixture is continuously stirred at a speed of 300 r / min with a stirrer;

[0069] (2) After step (1) reacts for 30 minutes, the pH value is adjusted to 8.5 with water glass solution until the solution solidifies into a gelatinous state, and then dried at 100° C. and ground into 200 mesh to obtain a heavy metal pollution remediation material.

[0070] Example 5

[0071] (1) The preparation process is carried out at room temperature. The preparation process is as follows Figure 1 As shown; Fe 3+ :PO4 3- Fe2(SO4)3·xH2O and Na2HPO4·12H2O in a molar ratio of 1:1.2 are fully dissolved in water, and 15% of the total mass of iron salt and phosphate white carbon black is added to the ferric sulfate solution. After stirring evenly, the pH value is adjusted to 2 with a sodium hydroxide solution with a concentration of 1 mol / L, and disodium hydrogen phosphate solution is added to the iron-containing mixed solution, and the mixture is continuously stirred at a speed of 300 r / min with a stirrer;

[0072] (2) After step (1) reacts for 30 minutes, the pH value is adjusted to 8.5 with water glass solution until the solution solidifies into a gelatinous state, and then dried at 100° C. and ground into 200 mesh to obtain a heavy metal pollution remediation material.

[0073] Example 6

[0074] (1) The preparation process is carried out at room temperature. The preparation process is as follows Figure 1 As shown; Fe 3+ :PO4 3- Fe2(SO4)3·xH2O and Na2HPO4·12H2O in a molar ratio of 1:1.5 are fully dissolved in water, and 15% of the total mass of iron salt and phosphate white carbon black is added to the ferric sulfate solution. After stirring evenly, the pH value is adjusted to 2 with a sodium hydroxide solution with a concentration of 1 mol / L, and disodium hydrogen phosphate solution is added to the iron-containing mixed solution, and the mixture is continuously stirred at a speed of 300 r / min with a stirrer;

[0075] (2) After step (1) reacts for 30 minutes, the pH value is adjusted to 8.5 with water glass solution until the solution solidifies into a gelatinous state, and then dried at 200° C. and ground into 200 mesh to obtain a heavy metal pollution remediation material.

[0076] Example 7

[0077] (1) The preparation process is carried out at room temperature. The preparation process is as follows Figure 1 As shown; Fe 3+ :PO4 3- Fe2(SO4)3·xH2O and Na2HPO4·12H2O in a molar ratio of 1:2 are fully dissolved in water, 10% of the total mass of iron salt and phosphate white carbon black is added to the ferric sulfate solution, and after stirring evenly, the pH value is adjusted to 2 with a sodium hydroxide solution with a concentration of 1 mol / L, and disodium hydrogen phosphate solution is added to the iron-containing mixed solution, and the mixture is continuously stirred at a speed of 300 r / min with a stirrer;

[0078] (2) After step (1) reacts for 30 minutes, the pH value is adjusted to 8.5 with water glass solution until the solution solidifies into a gelatinous state, and then dried at 100° C. and ground into 200 mesh to obtain a heavy metal pollution remediation material.

[0079] Example 8

[0080] (1) The preparation process is carried out at room temperature. The preparation process is as follows Figure 1 As shown; Fe 3+ :PO4 3-Fe2(SO4)3·xH2O and Na2HPO4·12H2O in a molar ratio of 1:1 are fully dissolved in water, 10% of the sum of the mass of iron salt and phosphate white carbon black is added to the ferric sulfate solution, and after stirring evenly, the pH value is adjusted to 2 with a sodium hydroxide solution with a concentration of 1 mol / L, and disodium hydrogen phosphate solution is added to the iron-containing mixed solution, and the mixture is continuously stirred at a speed of 400 r / min with a stirrer;

[0081] (2) After step (1) reacts for 30 minutes, the pH value is adjusted to 8.5 with water glass solution until the solution solidifies into a gelatinous state, and then dried at 100° C. and ground into 200 mesh to obtain a heavy metal pollution remediation material.

[0082] Comparative Example 1

[0083] This comparative example is compared with Example 8, and no mineral dispersant is added during the preparation process, and the rest is the same as Example 8.

[0084] Comparative Example 2

[0085] This comparative example is compared with Example 8. During the preparation process, no alkaline solution is added to adjust the pH to 2. Other aspects are the same as Example 8.

[0086] Comparative Example 3

[0087] Compared with Example 8, this comparative example is the same as Example 8 in that the pH value is adjusted using 1 mol / L sodium hydroxide solution instead of water glass during the preparation process.

[0088] Structural characterization

[0089] Figure 2 is a scanning electron microscope (SEM) image of the heavy metal pollution remediation material prepared in Examples 1, 2, 3, and 8. Figure 2 It can be seen that the surface of the heavy metal pollution remediation material prepared by the present invention is loose and porous.

[0090] The heavy metal pollution remediation materials prepared in other embodiments are characterized. The heavy metal pollution remediation materials prepared in other embodiments are also loose and porous, contain rich functional groups, have a pore size of 3 to 15 nm, and a specific surface area of ​​40 to 150 m 2 / g, total pore volume is 0.15~0.5cm 3 / g.

[0091] Performance Testing

[0092] (1) The test soil was taken from the contaminated soil around a lead-zinc mine in Hunan. After natural air drying, stones and plant residues were removed and the soil was passed through a 16-mesh filter and dried for later use.

[0093] The repair materials obtained in Examples 1 to 8 and Comparative Examples 1 and 2 were added to the above-mentioned contaminated soil at a mass ratio of 2%, mixed evenly, and the soil moisture content was maintained at about 40%. The curing temperature was 30°C, and a blank control experimental group without adding repair materials was set up. After 20 days of curing, the effective content of heavy (type) metals was determined (the extractant for effective Cd, Pb, Cu, and Zn was DTPA-CaCl2-TEA (HJ804-2016) solution, and the extractant for effective As and Sb was 0.5 mol / L NaHCO3 solution). The test results of the effective content of heavy (type) metals before and after repair are shown in Table 1 below:

[0094] Table 1 Results of remediation of contaminated soil around the lead-zinc mining area

[0095]

[0096] (2) A mixed solution of multiple (type) metals was prepared, and the concentration of each heavy (type) metal was adjusted to 25 mg / L, and the pH value of the solution was set to 5.0. The heavy (type) metal-contaminated wastewater was simulated, and the repair materials obtained in Examples 1 to 8 and Comparative Examples 1 and 2 were added respectively, and the dosage was controlled to be 1 g / L, the temperature was 25° C., and the mixture was continuously shaken for 24 hours and then filtered. The heavy (type) metal concentration in the filtrate was detected by ICP-AES inductively coupled atomic emission spectrometer. The heavy (type) metal content detection results in the solution before and after repair are shown in Table 2 below:

[0097] Table 2 Results of heavy metal content in wastewater before and after remediation

[0098]

[0099] As shown in Tables 1 and 2, the heavy metal pollution remediation material prepared by the present invention can simultaneously repair soil and water bodies contaminated by Cd, Pb, Cu, Zn, As and Sb, and the Fe content of soil and water bodies contaminated by different types of pollution can be adjusted according to the methods of Examples 1 to 8. 3+ and PO4 3- The ratio of phosphate compounds to stabilize Cd, Pb, Cu, and Zn, and iron (hydroxide) oxides to stabilize As and Sb, thereby achieving the maximum restoration of heavy (type) metals in different types of contaminated soil or water. In addition, it can be seen from the embodiments and comparative examples that adding an appropriate amount of mineral dispersant can promote the stabilization effect of the repair material on heavy (type) metals in contaminated soil and water to a certain extent.

[0100] 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 heavy metal pollution remediation material, characterized in that: The following steps are involved: Mixing a soluble ferric iron salt, a mineral dispersant and water to obtain an iron salt dispersion; Adjusting the pH value of the iron salt dispersion to 1.5-2.5, performing a first precipitation reaction, and obtaining a first precipitation reaction liquid; The first precipitation reaction liquid is mixed with a soluble phosphate to perform a second precipitation reaction to obtain a second precipitation reaction liquid; Using water glass to adjust the pH value of the second precipitation reaction liquid to 7-10, and solidify it to obtain a heavy metal pollution repair material; The mineral dispersant is one or more of sepiolite, white carbon black and kaolin; The particle size of the mineral dispersant is 10 to 100 nm; The mass of the mineral dispersant is 5-10% of the total mass of the soluble trivalent iron salt and the soluble phosphate.

2. The preparation method according to claim 1, characterized in that: The soluble ferric iron salt contains Fe 3+ With soluble phosphate PO4 3- The molar ratio is 1:0.4~2.

3. The preparation method according to claim 1, characterized in that: The temperatures of the first precipitation reaction and the second precipitation reaction are independently 15 to 40°C.

4. The preparation method according to claim 1, characterized in that: The modulus of the water glass is 3.3-4.

5. The preparation method according to claim 1, characterized in that: The soluble phosphate is added in the form of an aqueous solution, and the mass ratio of the soluble phosphate to water is 1:4.5-6.

5.

6. The preparation method according to claim 1, characterized in that: After the solidification, the obtained solidified material is dried and ground to obtain heavy metal pollution repair material powder, and the particle size of the heavy metal pollution repair material powder is 100-300 meshes.

7. The heavy metal pollution remediation material prepared by the preparation method according to any one of claims 1 to 6, wherein the chemical composition comprises phosphate compounds, iron hydroxide, hydroxyferric phosphate compounds and water glass; The pore size of the heavy metal pollution remediation material is 3 to 15 nm, and the specific surface area is 40 to 150 m 2 / g, total pore volume is 0.15~0.5cm 3 / g.

8. Use of the heavy metal pollution remediation material according to claim 7 in remediating heavy metal and metalloid polluted soil and / or heavy metal and metalloid polluted water.

9. The use according to claim 8, characterized in that: The heavy metal includes one or more of Cd, Pb, Cu and Zn, and the metalloid includes As and / or Sb.

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