A polymeric ferric sulfate-based calcareous enhanced passivation material for soil antimony pollution remediation and its preparation method

Abstract

The present invention discloses a polymeric ferric sulfate-based calcareous enhanced passivation material applied to the remediation of soil antimony pollution. The polymeric ferric sulfate-based calcareous enhanced passivation material contains the following components: 100 ml of water sample, 4 ml of polymeric ferric sulfate, 7 ml of lime milk, and 5 ml of polyacrylamide. Through soil cultivation, it is found that the polymeric ferric sulfate-based calcareous enhanced passivation material significantly reduces the contents of water-soluble + exchangeable antimony and carbonate-bound antimony in the soil compared with other materials and the control, significantly increases the content of residual antimony, and thus significantly reduces the bioavailability of antimony, achieving the best soil antimony passivation effect. At the same time, the polymeric ferric sulfate-based calcareous enhanced passivation material has no obvious effect on the soil pH. This passivation material is prepared from polymeric ferric sulfate and inexpensive lime as raw materials, with low cost, short preparation time, simple steps, easy operation, and good performance, and has excellent soil antimony passivation and remediation effects.

Description

Technical Field

[0001] The present invention relates to the field of soil antimony pollution remediation and passivation materials, and particularly to a polymeric ferric sulfate-based calcareous enhanced passivation material for soil antimony pollution remediation and a preparation method thereof. Background Art

[0002] Antimony is an important and widely distributed non-ferrous heavy metal, which is widely used in the industrial field. Antimony is one of the toxic pollutants preferentially controlled by the World Health Organization. The occurrence form of antimony determines its toxicity intensity and bioavailability. The solidification-stabilization technology is the main remediation technology for soil heavy metal pollution at home and abroad. For the passivation remediation materials of antimony-contaminated soil, ferric salts are mostly selected.

[0003] However, ferric salts are not obvious enough in reducing the content of water-soluble, exchangeable antimony and carbonate-bound antimony in soil, and the passivation effect is not good; secondly, improper use of ferric salts will cause soil acidification and at the same time affect the solidification-stabilization effect of soil antimony; in addition, the existing passivation materials for soil antimony pollution remediation have high preparation costs, long preparation times, cumbersome steps, difficult operation, and poor performance, and the soil antimony passivation remediation effect is not good. Summary of the Invention

[0004] The purpose of the present invention is to provide a polymeric ferric sulfate-based calcareous enhanced passivation material for soil antimony pollution passivation remediation. Ferric salts are not obvious enough in reducing the content of water-soluble, exchangeable antimony and carbonate-bound antimony in soil, and the passivation effect is not good. Secondly, improper use of ferric salts will cause soil acidification and at the same time affect the passivation effect of soil antimony pollution; in addition, the existing passivation materials for soil antimony pollution remediation have high preparation costs, long preparation times, cumbersome steps, difficult operation, and poor performance, and the soil antimony passivation remediation effect is not good. The present invention hydrolyzes polymeric ferric sulfate and reacts with lime (pH = 8), and at the same time adds a flocculant polyacrylamide (PAM). The flocculated and precipitated product is then dried and dry ball milled. The prepared material is used to repair antimony-contaminated soil. Through soil cultivation, it is found that the polymeric ferric sulfate-based calcareous enhanced passivation material significantly reduces the content of water-soluble + exchangeable antimony and carbonate-bound antimony in soil compared with other materials and the control, significantly increases the content of residual antimony, and thus significantly reduces the bioavailability of antimony, making the soil antimony passivation effect reach the best. At the same time, the polymeric ferric sulfate-based calcareous enhanced passivation material has no obvious impact on the soil pH. This passivation material is prepared from polymeric ferric sulfate and cheap lime as raw materials, with low cost, short preparation time, simple steps, easy operation, and good performance, and has an excellent soil antimony passivation remediation effect.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A polymeric ferric sulfate-based calcareous enhanced passivation material for passivation and remediation of soil antimony pollution, the polymeric ferric sulfate-based calcareous enhanced passivation material containing the following components: 100 ml of water sample, 4 ml of polymeric ferric sulfate, 7 ml of lime milk, and 5 ml of polyacrylamide.

[0007] As a further aspect of the present invention, the preparation concentrations of the polymeric ferric sulfate and the lime milk are both 5%, and the preparation concentration of the polyacrylamide is 1‰.

[0008] A polymeric ferric sulfate-based calcareous enhanced passivation material for passivation and remediation of soil antimony pollution and a preparation method thereof, the specific steps of the preparation method being as follows:

[0009] Step 1: Pour 100 ml of water sample into a beaker, place the beaker on a magnetic stirrer for stirring, and add 4 ml of polymeric ferric sulfate during the stirring process;

[0010] Step 2: After reacting for a period of time, slowly add lime milk to adjust the pH;

[0011] Step 3: Continue stirring for reaction, then add 5 ml of polyacrylamide for flocculation precipitation, discard the supernatant, and place the beaker in an oven for drying;

[0012] Step 4: Grind the dried material into a powder in a dry ball mill for standby.

[0013] As a further aspect of the present invention, in the said Step 1, the rotation speed of the magnetic stirrer is 2000 rmp.

[0014] As a further aspect of the present invention, in the said Step 2, the reaction time is 5 min, the final adjusted pH = 8, and the final dosage of the lime milk is 7 ml.

[0015] As a further aspect of the present invention, in the said Step 3, the reaction time for continuing stirring for reaction is 1 h, and the drying time is 48 h.

[0016] Advantages of the present invention:

[0017] The present invention utilizes the hydrolysis of polymeric ferric sulfate and reacts it with lime (pH = 8), while adding the flocculant polyacrylamide (PAM). The product of flocculation precipitation is then dried and subjected to dry ball milling. The prepared material is used for the remediation of antimony-contaminated soil. Through soil cultivation, it is found that the polymeric ferric sulfate-based calcareous enhanced passivation material significantly reduces the contents of water-soluble + exchangeable antimony and carbonate-bound antimony in the soil compared with other materials and the control, significantly increases the content of residual antimony, and thus significantly reduces the bioavailability of antimony, achieving the best soil antimony passivation effect. At the same time, the polymeric ferric sulfate-based calcareous enhanced passivation material has no obvious effect on the soil pH and does not cause soil acidification. This passivation material is prepared from polymeric ferric sulfate and inexpensive lime as raw materials, with low cost, short preparation time, simple steps, easy operation, and good performance, and has excellent soil antimony passivation and remediation effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a bar chart showing the changes in the forms of antimony in soil treated with a polymeric ferric sulfate-based calcareous enhanced passivation material for the passivation and remediation of soil antimony pollution according to the present invention;

[0019] Note: CK, FC, FS, and PFS represent the control treatment, ferric chloride-based calcareous passivation material treatment, ferric sulfate-based calcareous passivation material treatment, and polymeric ferric sulfate-based calcareous enhanced passivation material treatment, respectively.

[0020] Figure 2 It is a bar chart of the soil pH under the treatment of a polymeric ferric sulfate-based calcareous enhanced passivation material for the passivation and remediation of soil antimony pollution according to the present invention.

[0021] Note: CK, FC, FS, and PFS represent the control treatment, ferric chloride-based calcareous passivation material treatment, ferric sulfate-based calcareous passivation material treatment, and polymeric ferric sulfate-based calcareous enhanced passivation material treatment, respectively. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0023] A polymeric ferric sulfate-based calcareous enhanced passivation material for the passivation and remediation of soil antimony pollution, which contains the following components: 100 ml of water sample, 4 ml of polymeric ferric sulfate, 7 ml of lime milk, and 5 ml of polyacrylamide.

[0024] In this solution, the preparation concentrations of polyferric sulfate and lime milk are both 5%, and the preparation concentration of polyacrylamide is 1‰.

[0025] A polyferric sulfate-based lime reinforced passivation material for passivation and remediation of soil antimony pollution and its preparation method. The specific steps of the preparation method are as follows:

[0026] Step 1: Pour 100 ml of water sample into a beaker, place the beaker on a magnetic stirrer and stir. During the stirring process, add 4 ml of polyferric sulfate.

[0027] Step 2: After reacting for a period of time, slowly add lime milk to adjust the pH.

[0028] Step 3: Continue to stir for reaction, then add 5 ml of polyacrylamide for flocculation precipitation, discard the supernatant, and put the beaker into an oven to dry.

[0029] Step 4: Grind the dried material into powder in a dry ball mill for standby.

[0030] In this solution, in Step 1, the rotation speed of the magnetic stirrer is 2000 rmp.

[0031] In this solution, in Step 2, the reaction time is 5 min, the final adjusted pH = 8, and the final dosage of lime milk is 7 ml.

[0032] In this solution, in Step 3, the reaction time for continuing to stir for reaction is 1 h, and the drying time is 48 h.

[0033] To better illustrate the passivation and remediation effect of the polyferric sulfate-based lime reinforced passivation material on soil antimony pollution, the preparation of the control material and its experiment are carried out:

[0034] Preparation method of control material 1: As the control material of the polyferric sulfate-based lime reinforced passivation material, pour 100 ml of water sample into a beaker, place the beaker on a magnetic stirrer and stir. During the stirring process, add 4 ml of ferric sulfate (preparation concentration: 5%). After 5 min, slowly add 7 ml of lime milk (preparation concentration: 5%) to adjust the pH. When the pH reaches 8, continue to stir for 1 h for reaction, and then add 5 ml of polyacrylamide (PAM, preparation concentration: 1‰) to flocculate the precipitate. Discard the supernatant, put the beaker into the oven and dry for 48 h, and grind the dried material into powder in a dry ball mill for standby.

[0035] Preparation of Control Material 2: As a control material for the polyferric sulfate-based lime-based reinforced passivation material, 100 ml of water sample was poured into a beaker and stirred on a magnetic stirrer. During the stirring process, 4 ml of ferric chloride (prepared concentration: 5%) was added. After 5 minutes, 7 ml of lime milk (prepared concentration: 5%) was slowly added to adjust the pH. When the pH reached 8, stirring was continued for 1 hour to allow the reaction to proceed. Subsequently, 5 ml of polyacrylamide (PAM, prepared concentration: 1‰) was added to flocculate the precipitate. The supernatant was discarded, and the beaker was placed in an oven for 48 hours to dry. The dried material was then dry-milled to a powder for later use.

[0036] experiment:

[0037] (1) Soil sample collection: The plum blossom sampling method was used. 4-5 soil samples (0-20 cm) were collected from each sampling point and thoroughly mixed. After being transported back to the laboratory, the samples were air-dried, ground, and passed through a 60-mesh sieve.

[0038] (2) Experimental design: The prepared polyferric sulfate-based calcareous passivation material was selected as the experimental material, the prepared ferric sulfate-based calcareous passivation material and ferric chloride-based calcareous passivation material were used as the control materials, and the Sb-contaminated soil was used as the experimental object. A total of four treatments were set up, namely the control (CK, no material added) treatment, the ferric chloride-based calcareous passivation material (FC, control material) treatment, the ferric sulfate-based calcareous passivation material (FS, control material) treatment, and the polyferric sulfate-based calcareous passivation material treatment (PFS). Each treatment was set up with four parallels. The addition amount of all materials was 5% of the dry soil weight. The equipment used for the incubation experiment was a 500 mL plastic box. Weigh 200 g of dry soil, mix it thoroughly with the repair material, and then put it into the culture pot. Add water to adjust the soil moisture content to 50%. Use the weighing method to replenish water once every two days. After 15 days of indoor incubation, sample and measure the Sb content in the soil.

[0039] (3) Soil Sb Content Determination Method: The Tessier sequential extraction method was used to determine the water-soluble, exchangeable, carbonate-bound, iron-manganese oxide-bound, organic-bound, and residual Sb contents. Determination was performed by inductively coupled plasma mass spectrometry (ICP-MS). National standard material (soil: GBW07410) was used for quality control. Blanks and replicates were prepared for all samples. The results of the standard samples were all within the permitted range.

[0040] (4) Analysis of experimental results:

[0041] Depend on Figure 1It can be seen that, compared with the control, the ferric chloride-based calcareous passivation material reduces the contents of water-soluble + exchangeable Sb, carbonate-bound Sb, and Fe-Mn oxide-bound Sb by 45.3%, 22.2%, and 4.8% respectively, and increases the contents of organically-bound Sb and residual Sb by 11.5% and 33.9% respectively; the ferric sulfate-based calcareous passivation material reduces the contents of water-soluble + exchangeable Sb, carbonate-bound Sb, and Fe-Mn oxide-bound Sb by 75.1%, 40.2%, and 4.0% respectively, and increases the contents of organically-bound Sb and residual Sb by 10.5% and 53.5% respectively; the polyferric sulfate-based calcareous enhanced passivation material reduces the contents of water-soluble + exchangeable Sb, carbonate-bound Sb, and Fe-Mn oxide-bound Sb by 93.1%, 88.3%, and 25.1% respectively, and increases the contents of organically-bound Sb and residual Sb by 74.4% and 82.4% respectively. Thus, it can be seen that the prepared polyferric sulfate-based calcareous enhanced passivation material can significantly reduce the contents of water-soluble + exchangeable Sb and carbonate-bound Sb in the antimony-contaminated soil compared with the control and the other two ferric chloride-based calcareous passivation materials, significantly increase the content of residual Sb, and thus significantly reduce the bioavailability of Sb.

[0042] It can be seen from Figure 2 that, compared with the control and the treatments with the other two passivation materials, there is no significant change in the soil pH in the treatment with the polyferric sulfate-based calcareous enhanced passivation material. Therefore, the polyferric sulfate-based calcareous enhanced passivation material does not cause soil acidification or an increase in the mobility and bioavailability of soil heavy metal ions due to changes in soil pH.

[0043] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a polymeric ferric sulfate-based calcareous enhanced passivation material applied to soil antimony adsorption, characterized in that: The raw materials of the polymeric ferric sulfate-based calcareous strengthening passivation material are composed of the following components: 100 ml of water sample, 4 ml of polymeric ferric sulfate, 7 ml of lime milk, and 5 ml of polyacrylamide; the configured concentrations of the polymeric ferric sulfate and the lime milk are both 5%, and the configured concentration of the polyacrylamide is 1‰; the specific steps of the preparation method are as follows: Step 1: Pour 100 ml of water sample into a beaker, place the beaker on a magnetic stirrer for stirring, and add 4 ml of polymeric ferric sulfate during the stirring process; in Step 1, the rotation speed of the magnetic stirrer is 2000 rmp; Step 2: After reacting for a period of time, slowly add lime milk to adjust the pH; in Step 2, the reaction time is 5 min, the final adjusted pH = 8, and the final dosage of lime milk is 7 ml; Step 3: Continue stirring for reaction, then add 5 ml of polyacrylamide for flocculation precipitation, discard the supernatant, and place the beaker in an oven for drying; in Step 3, the reaction time for continuing stirring for reaction is 1 h, and the drying time is 48 h; Step 4: Grind the dried material into powder by dry ball milling for standby.

2. A polymeric ferric sulfate-based calcareous strengthening passivation material prepared by the method according to claim 1 and applied to soil antimony adsorption.

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