Efficient soil heavy metal solidification and stabilization agent and preparation method thereof

Abstract

The invention relates to the technical field of environmental protection, and provides an efficient soil heavy metal solidification and stabilization agent and a preparation method thereof. The efficient soil heavy metal solidification and stabilization agent comprises the following raw materials in parts by weight: 15-25 parts of cement, 5-15 parts of sodium sulfite, 50-70 parts of an auxiliary agent and 10-30 parts of montmorillonite. By means of the technical scheme, the problem that in the related technology, the soil heavy metal curing and stabilizing agent is low in soil heavy metal treatment efficiency is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection, and in particular to a highly effective soil heavy metal solidification and stabilization agent and a preparation method thereof. Background Art

[0002] Heavy metal pollution in soil is one of the major environmental problems facing the world. With the development of industry, accelerated urbanization and the impact of agricultural production activities, the content of heavy metals in the soil continues to increase, which will not only damage the soil ecosystem, but also be transmitted through the food chain, threatening human health.

[0003] Existing soil solidification and stabilization agents have weak solidification and stabilization capabilities for heavy metals in the soil and low efficiency in heavy metal treatment. As a result, a large amount of solidification and stabilization agents are required in the soil remediation process. The increase in the amount will cause waste of resources and damage to the soil ecosystem. Therefore, it is necessary to develop an efficient soil heavy metal solidification and stabilization agent. Summary of the invention

[0004] The present invention provides a highly efficient soil heavy metal solidification and stabilization agent and a preparation method thereof, which solves the problem of low efficiency of soil heavy metal treatment by soil heavy metal solidification and stabilization agents in the related art.

[0005] The technical solution of the present invention is as follows: The present invention proposes a high-efficiency soil heavy metal solidification and stabilization agent, comprising the following raw materials in parts by weight: 15 to 25 parts of cement, 5 to 15 parts of sodium sulfite, 30 to 70 parts of auxiliary agent, and 10 to 30 parts of montmorillonite.

[0006] As a further technical solution, the auxiliary agent includes one or more of fly ash, quicklime, and zeolite.

[0007] As a further technical solution, the auxiliary agent is zeolite.

[0008] In the present invention, the preferred auxiliary material is zeolite, because it is a neutral agent. Compared with alkaline agents such as fly ash and quicklime, zeolite and cement can reduce the pH of the leachate and enhance the solidification and stabilization effect of the solidification and stabilization agent on heavy metals in the soil.

[0009] As a further technical solution, when the auxiliary agent is zeolite, the zeolite is activated zeolite, and the preparation method of the activated zeolite is: subjecting the zeolite to high temperature activation to obtain high temperature activated zeolite, and then subjecting the high temperature zeolite to acid activation to obtain activated zeolite.

[0010] In the present invention, the zeolite is activated in two steps, by adjusting the structure of the zeolite, unblocking the zeolite pores, increasing the porosity of the zeolite, increasing the adsorption sites of the zeolite, improving the surface properties of the zeolite, and increasing the surface activity of the zeolite, the treatment efficiency of the solidification and stabilization agent for heavy metals in soil is further improved.

[0011] As a further technical solution, the high temperature activation process comprises the following steps: calcining the zeolite and cooling it to obtain the high temperature activated zeolite.

[0012] As a further technical solution, the calcination is carried out in a muffle furnace.

[0013] As a further technical solution, the calcination temperature is 450° C. and the calcination time is 3 hours.

[0014] As a further technical solution, the heating rate of the calcination is 10°C / min.

[0015] As a further technical solution, the acid activation comprises the following steps: placing the high temperature activated zeolite in an acid solution for acid leaching, filtering and drying to obtain the activated zeolite.

[0016] As a further technical solution, the volume mass ratio of the acid solution to the high temperature activated zeolite is 10 mL:1 g.

[0017] As a further technical solution, the acid leaching time is 4 hours.

[0018] As a further technical solution, the acid solution includes hydrochloric acid.

[0019] As a further technical solution, the concentration of the hydrochloric acid is 1 mol / L.

[0020] As a further technical solution, the acid solution also includes an organic acid, and the volume ratio of the hydrochloric acid to the organic acid is 3-4:1.

[0021] In the present invention, a mixed acid of hydrochloric acid and an organic acid is used simultaneously to activate the zeolite, thereby exerting a synergistic effect of the two, improving the adsorption performance of the zeolite, enhancing the stability of the zeolite surface charge, and further improving the treatment efficiency of the solidification and stabilization agent for soil heavy metals.

[0022] As a further technical solution, the organic acid includes one or more of acetic acid, citric acid, and benzenesulfonic acid.

[0023] As a further technical solution, the concentration of the organic acid is 1 mol / L.

[0024] As a further technical solution, the activated zeolite is a modified activated zeolite, and the modified activated zeolite is obtained by modifying the activated zeolite with a modifier, and the modifier is a mercaptobenzamide compound.

[0025] In the present invention, the mercaptobenzamide compound is used to modify the zeolite, and new active sites are introduced on the surface of the zeolite to increase the adsorption capacity, thereby further improving the treatment efficiency of the solidification and stabilization agent on soil heavy metals.

[0026] As a further technical solution, the mercaptobenzamide compound includes one or two of 2-mercaptobenzamide and 4-mercapto-benzenesulfonamide.

[0027] As a further technical solution, the raw materials of the modified activated zeolite include a modifier and an activated zeolite in a mass ratio of 1 to 2:20.

[0028] As a further technical solution, the preparation method of the modified activated zeolite comprises the following steps: dispersing the modifier in a solution, adding the activated zeolite, stirring, filtering and drying to obtain the modified activated zeolite.

[0029] As a further technical solution, the solution is acetone, and the mass ratio of the solution to the activated zeolite is 10:1.

[0030] As a further technical solution, the stirring time is 2 hours.

[0031] The present invention also provides a method for preparing a highly efficient soil heavy metal solidification and stabilization agent, comprising the following steps: mixing the raw materials uniformly to obtain the solidification and stabilization agent.

[0032] As a further technical solution, the mixing time is 2 hours.

[0033] The working principle and beneficial effects of the present invention are: In the present invention, cement is used as a curing agent, which can encapsulate heavy metal ions and restrict their movement in the soil. It is used in combination with an auxiliary agent to exert the synergistic effect of the two, enhance the adsorption effect of the stabilization agent on soil heavy metals, and improve the treatment efficiency of the curing and stabilization agent on soil heavy metals. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0035] In the following examples and comparative examples: Fly ash: average particle size is 325 mesh; Cement: Model: P·O42.5; Zeolite: average particle size is 325 mesh; Montmorillonite: average particle size is 325 mesh; Quicklime: The average particle size is 325 mesh.

[0036] Example 1 A method for preparing an efficient soil heavy metal solidification and stabilization agent comprises the following steps: 25 parts of cement, 15 parts of sodium sulfite, 30 parts of fly ash and 30 parts of montmorillonite are stirred and mixed for 2 hours to obtain a solidification and stabilization agent.

[0037] Example 2 A method for preparing an efficient soil heavy metal solidification and stabilization agent comprises the following steps: 20 parts of cement, 10 parts of sodium sulfite, 50 parts of fly ash and 20 parts of montmorillonite are stirred and mixed for 2 hours to obtain a solidification and stabilization agent.

[0038] Example 3 A method for preparing an efficient soil heavy metal solidification and stabilization agent comprises the following steps: 15 parts of cement, 5 parts of sodium sulfite, 70 parts of fly ash and 10 parts of montmorillonite are stirred and mixed for 2 hours to obtain a solidification and stabilization agent.

[0039] Example 4 Compared with Example 1, the difference of Example 4 is that fly ash is replaced by an equal amount of quicklime.

[0040] Example 5 Compared with Example 1, Example 5 is different in that fly ash is replaced by an equal amount of zeolite.

[0041] Example 6 The preparation method of activated zeolite comprises the following steps: placing the zeolite into a muffle furnace, controlling the heating rate to be 10°C / min, heating to 450°C, activating at a constant temperature for 3 hours, cooling and taking out, thereby obtaining the high-temperature activated zeolite; Compared with Example 5, the difference of Example 6 is that the zeolite is replaced by an equal amount of activated zeolite obtained by the above preparation method.

[0042] Example 7 The preparation method of activated zeolite comprises the following steps: placing zeolite in a hydrochloric acid solution (with a concentration of 1 mol / L), acid-leaching for 4 hours, filtering and drying to obtain activated zeolite, wherein the volume mass ratio of the hydrochloric acid solution to the zeolite is 10 mL:1 g; Compared with Example 5, the difference of Example 7 is that the zeolite is replaced by an equal amount of activated zeolite obtained by the above preparation method.

[0043] Example 8 The preparation method of activated zeolite comprises the following steps: placing the zeolite into a muffle furnace, controlling the heating rate to be 10°C / min, heating to 450°C, activating at a constant temperature for 3 hours, cooling and taking out to obtain the high-temperature activated zeolite, placing the high-temperature activated zeolite into a hydrochloric acid solution (with a concentration of 1 mol / L), acid-leaching for 4 hours, filtering and drying to obtain the activated zeolite, wherein the volume mass ratio of the hydrochloric acid solution to the zeolite is 10 mL:1 g; Compared with Example 5, the difference of Example 8 is that the zeolite is replaced by an equal amount of activated zeolite obtained by the above preparation method.

[0044] Example 9 Compared with Example 8, the difference of Example 9 is that the hydrochloric acid solution is replaced by an equal volume of acetic acid solution (with a concentration of 1 mol / L).

[0045] Example 10 Compared with Example 8, the difference of Example 10 is that the hydrochloric acid solution is replaced by a hydrochloric acid solution (with a concentration of 1 mol / L) and an acetic acid solution (with a concentration of 1 mol / L) in a volume ratio of 3:1.

[0046] Embodiment 11 Compared with Example 10, Example 11 is different in that the acetic acid solution (with a concentration of 1 mol / L) is replaced with an equal volume of citric acid solution (with a concentration of 1 mol / L).

[0047] Example 12 Compared with Example 10, the difference in Example 12 is that the acetic acid solution (with a concentration of 1 mol / L) is replaced by an equal volume of benzenesulfonic acid solution (with a concentration of 1 mol / L).

[0048] Example 13 Compared with Example 12, the difference in Example 13 is that the volume ratio of the hydrochloric acid solution (concentration of 1 mol / L) to the benzenesulfonic acid solution (concentration of 1 mol / L) is 4:1.

[0049] Embodiment 14 The preparation method of the modified activated zeolite comprises the following steps: dispersing 2-mercaptobenzamide in acetone, adding the activated zeolite prepared in Example 13, stirring for 2 hours, filtering and drying to obtain the modified activated zeolite, wherein the mass ratio of 2-mercaptobenzamide to the activated zeolite is 1:20, and the mass ratio of acetone to the activated zeolite is 10:1; Compared with Example 13, the difference of Example 14 is that the zeolite is replaced by the modified activated zeolite obtained by the above preparation method.

[0050] Embodiment 15 Compared with Example 14, the difference of Example 15 is that 2-mercaptobenzamide is replaced by an equal amount of 4-mercapto-benzenesulfonamide.

[0051] Example 16 Compared with Example 15, the difference in Example 16 is that the mass ratio of the amount of 4-mercapto-benzenesulfonamide to the activated zeolite is 2:20.

[0052] Comparative Example 1 Compared with Example 1, Comparative Example 1 is different in that fly ash is not added.

[0053] The solidification stabilization agents prepared in Examples 1 to 16 and Comparative Example 1 were tested according to the following method: The method for preparing the solidified body to be tested comprises the following steps: A1. The same composite heavy metal contaminated soil (Cr 0.37 mg / kg; Cu 331 mg / kg; Zn 429 mg / kg) was crushed and passed through a 25-mesh sieve, and then the solidification and stabilization agent prepared in Examples 1 to 16 and Comparative Example 1 was added, and the amount of the solidification and stabilization agent added was 1.2%. The mixture was stirred evenly in a stirring device, and water was added to form a contaminated soil slurry with a water content of 30 wt%; A2. Pour the contaminated soil slurry into a mold with a size of 100 mm × 100 mm × 100 mm, and vibrate and compact it to obtain a solidified body of the contaminated soil; A3. After demoulding the solidified body, the solidified body to be tested was obtained by curing it for 7 days under standard curing conditions.

[0054] 1. Leachate detection: According to the test method specified in HJ 557-2010 "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method", the leachate of the solidified body to be tested is tested.

[0055] The test results are shown in the following table: Table 1 Performance test results of the solidified bodies prepared in Examples 1 to 16 and Comparative Example 1

[0056] Compared with Comparative Example 1, Example 1 adds fly ash as an adjuvant. As a result, the chromium content, copper content and zinc content of Example 1 are all lower than those of Comparative Example 1, indicating that when adjuvants are added, the treatment efficiency of the solidification and stabilization agent for soil heavy metals can be improved.

[0057] Compared with Example 1, Examples 4 and 5 added different types of adjuvants. As a result, the copper content and zinc content of Example 5 were both lower than those of Examples 1 and 4, indicating that when the added adjuvant is zeolite, the treatment efficiency of the solidification and stabilization agent for soil heavy metals can be further improved.

[0058] Compared with Example 5, Examples 6 to 9 activated the zeolite. As a result, the copper content and zinc content of Examples 6 to 9 were lower than those of Example 5, indicating that after the zeolite was activated, the obtained solidified stabilization agent had a higher treatment efficiency for soil heavy metals.

[0059] Compared with Examples 6 and 7, Examples 8 and 9 first perform high-temperature activation on the zeolite and then perform acid activation. As a result, the copper content and zinc content of Examples 8 and 9 are both lower than those of Examples 6 and 7, indicating that when the zeolite is activated in two steps, the treatment efficiency of the solidification and stabilization agent for soil heavy metals can be further improved.

[0060] Compared with Examples 8 and 9, Examples 10 to 13 simultaneously used hydrochloric acid and organic acid to activate the zeolite. As a result, the copper content and zinc content of Examples 10 to 13 were both lower than those of Examples 8 and 9, indicating that hydrochloric acid and organic acid exerted a synergistic effect and could further improve the treatment efficiency of the solidification and stabilization agent for soil heavy metals.

[0061] In Examples 10 to 12, different types of organic acids were added and mixed with hydrochloric acid. As a result, the copper content and zinc content of Example 12 were lower than those of Examples 10 and 11, indicating that when the organic acid is benzenesulfonic acid, the obtained solidification and stabilization agent has a higher treatment efficiency for soil heavy metals.

[0062] Compared with Example 13, Examples 14 to 16 modified the zeolite. As a result, the copper content and zinc content of Examples 14 to 16 were lower than those of Example 13, indicating that when modified activated zeolite is added, the treatment efficiency of the solidification and stabilization agent for soil heavy metals can be further improved.

[0063] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A highly efficient soil heavy metal solidification and stabilization agent, characterized in that: The raw materials include the following components in parts by weight: 15-25 parts of cement, 5-15 parts of sodium sulfite, 50-70 parts of auxiliary agent and 10-30 parts of montmorillonite.

2. A highly efficient soil heavy metal solidification and stabilization agent according to claim 1, characterized in that: The auxiliary agent includes one or more of fly ash, quicklime and zeolite.

3. A highly efficient soil heavy metal solidification and stabilization agent according to claim 2, characterized in that: When the auxiliary agent is zeolite, the zeolite is activated zeolite, and the preparation method of the activated zeolite is: subjecting the zeolite to high temperature activation to obtain high temperature activated zeolite, and then subjecting the high temperature zeolite to acid activation to obtain activated zeolite.

4. A highly efficient soil heavy metal solidification and stabilization agent according to claim 3, characterized in that: The acid activation comprises the following steps: placing the high temperature activated zeolite in an acid solution for acid leaching, filtering and drying to obtain the activated zeolite.

5. A highly efficient soil heavy metal solidification and stabilization agent according to claim 4, characterized in that: The acid solution includes hydrochloric acid.

6. A highly efficient soil heavy metal solidification and stabilization agent according to claim 5, characterized in that: The acid solution also includes an organic acid, and the volume ratio of the hydrochloric acid to the organic acid is 3-4:

1.

7. A highly efficient soil heavy metal solidification and stabilization agent according to claim 6, characterized in that: The organic acid includes one or more of acetic acid, citric acid and benzenesulfonic acid.

8. The highly efficient soil heavy metal solidification and stabilization agent according to claim 3, characterized in that: The activated zeolite is a modified activated zeolite, and the modified activated zeolite is obtained by modifying the activated zeolite with a modifier, and the modifier is a mercaptobenzamide compound.

9. The high-efficiency soil heavy metal solidification and stabilization agent according to claim 8, characterized in that: The mercaptobenzamide compound includes one or both of 2-mercaptobenzamide and 4-mercapto-benzenesulfonamide.

10. The method for preparing a highly efficient soil heavy metal solidification and stabilization agent according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: the raw materials are mixed evenly to obtain a solidifying and stabilizing agent.

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