Pharmaceutical and method for repairing hexavalent chromium contaminated soil in one step

Abstract

The present application provides a one-step method for repairing hexavalent chromium contaminated soil and a reagent thereof. The reagent for repairing hexavalent chromium contaminated soil in the one-step method comprises a reducing agent, a stabilizing agent and a crystallization modifier; the reducing agent is at least one of a sulfur-containing compound with reducing property and an organic reducing agent; the stabilizing agent is at least one of a slightly soluble calcium phosphate salt and a slightly soluble magnesium phosphate salt; and the crystallization modifier is at least one of OP-10 and JFC-2. In the present application, the phosphate salt is slightly soluble, the concentration of phosphate in the soil is low, and the reaction with the trivalent chromium ion produced by the reduction reaction is relatively slow, so that the chromium phosphate crystal is obtained, and the stability is good. However, the phosphate salt is a slightly soluble salt, and the migration property is relatively poor. Therefore, the crystallization modifier is added to improve the migration effect. At the same time, the crystallization modifier has a surface active group, which can change the interfacial properties and improve the crystallization form of the chromium phosphate, so that the long-term stability of chromium is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of soil pollution remediation, and particularly relates to a medicament and a method for remediation of hexavalent chromium contaminated soil by one-step method. BACKGROUND

[0002] A series of remediation technologies for chromium contaminated soil have been developed at home and abroad, and the mainstream technologies are leaching technology, reduction-stabilization remediation technology, electrokinetic remediation technology, bioremediation technology, immobilization / stabilization technology, etc.

[0003] Among them, the reduction-stabilization remediation technology is the most widely used remediation technology for chromium contaminated soil. The use of reducing materials to chemically reduce Cr(Ⅵ) to Cr(Ⅲ) is the most widely used Cr(Ⅵ) contaminated soil remediation technology, which has high efficiency, strong adaptability and low cost. More importantly, in engineering practice, Cr(Ⅵ) contaminated soil also generally follows the strategy of in-situ Cr(Ⅵ) reduction and reduction precipitation / immobilization, and most of the completed and ongoing remediation projects have adopted chemical reduction remediation technology.

[0004] Generally, the chemical reduction and stabilization process uses direct reduction and is achieved by adjusting the pH value. Hexavalent chromium is reduced to trivalent chromium, and at a higher pH value, trivalent chromium forms chromium hydroxide. Since the solubility of chromium hydroxide is relatively small, it is relatively stable in soil, but this stabilization effect is poor. With the consumption of reducing agents in the soil and the decrease of pH value, chromium hydroxide is easily dissolved and oxidized to hexavalent chromium. Generally speaking, the higher the concentration of dissolved Cr(Ⅲ), the faster the oxidation rate and the higher the oxidation degree. The rate of Cr(Ⅲ) oxidation is mainly related to its solubility. The higher the concentration of soluble chromium (Ⅲ), the relatively faster the oxidation rate.

[0005] Therefore, people have proposed a phosphate stabilization process. Since the solubility of chromium phosphate is much lower than that of chromium hydroxide, it is relatively difficult to dissolve in soil and is not easily oxidized again, and is more stable. The soluble phosphates used include trisodium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, potassium hydrogen phosphate, etc. However, research has found that this reduction and stabilization process is more suitable for a two-step method, i.e. first reducing hexavalent chromium to trivalent chromium with a reducing agent, and then adding phosphate after a period of time (usually 3-5 days), so as to obtain a better stabilization effect.

[0006] For example, the patent application with publication number CN117019857A discloses a method for repairing hexavalent chromium contaminated soil, which comprises the following steps: S1, mixing a reducing agent with soil uniformly, then adding water, so that the soil is in an anaerobic environment and is left standing; S2, adding a stabilizing agent to fix the reduced hexavalent chromium, so as to realize the repair of hexavalent chromium contaminated soil; the reducing agent is one or more of ferrous sulfate heptahydrate, attapulgite, oxalic acid, urea and zero-valent iron; the stabilizing agent is one or more of biochar, quicklime, calcium-magnesium phosphate fertilizer or water-soluble silicon fertilizer.

[0007] However, the two-step method is more troublesome, has a long period, occupies the repair equipment for a long period, and has high cost, especially for in-situ repair. After the one-step reduction is completed, the soil is in a slurry state, and the mechanical equipment needs to be removed, so that it is difficult to inject the reagent for the second construction. How to utilize the stability of phosphoric acid chromium and realize the one-step reduction and stabilization process is one of the technical problems to be solved at present.

[0008] However, the two-step method is more troublesome, has a long period, occupies the repair equipment for a long period, and has high cost, especially for in-situ repair. After the one-step reduction is completed, the soil is in a slurry state, and the mechanical equipment needs to be removed, so that it is difficult to inject the reagent for the second construction. How to utilize the stability of phosphoric acid chromium and realize the one-step reduction and stabilization process is one of the technical problems to be solved at present. SUMMARY

[0009] To solve the above technical problems in the prior art, the present application provides a reagent and method for repairing hexavalent chromium contaminated soil by one-step method.

[0010] The present application provides a reagent for repairing hexavalent chromium contaminated soil by one-step method, which comprises a reducing agent, a stabilizing agent and a crystallization modifier; the reducing agent is at least one of a sulfur-containing compound with reducing property and an organic reducing agent; the stabilizing agent is at least one of a slightly soluble calcium phosphate salt and a slightly soluble magnesium phosphate salt; and the crystallization modifier is at least one of OP-10 and JFC-2.

[0011] Preferably, the reducing sulfur-containing compound is at least one of sodium metabisulfite, sodium dithionite, sodium sulfite, potassium metabisulfite, potassium dithionite, and potassium sulfite; the organic reducing agent is at least one of glucose, ethanol, and ascorbic acid; and the stabilizing agent is at least one of calcium hydrogen phosphate (CAS: 7757-93-9), magnesium hydrogen phosphate (CAS: 7782-75-4), and calcium magnesium phosphate.

[0012] Preferably, the mass ratio of the reducing agent to the stabilizing agent is 2-5:1, and the mass ratio of the stabilizing agent to the crystallization modifier is 25-368:1.

[0013] Further preferably, the mass ratio of the reducing agent to the stabilizing agent is 2-3:1.

[0014] Further preferably, the mass ratio of the stabilizing agent to the crystallization modifier is 40-124:1.

[0015] The application also provides the use of the above-mentioned agent for repairing hexavalent chromium contaminated soil in a one-step method in removing hexavalent chromium ions in soil.

[0016] The application also provides a method for repairing hexavalent chromium contaminated soil in a one-step method, comprising the following steps: adding the above-mentioned agent for repairing hexavalent chromium contaminated soil in a one-step method to the hexavalent chromium contaminated soil, adjusting the water content of the hexavalent chromium contaminated soil to 20%-60%, and then mixing uniformly and curing under anaerobic or oxygen-isolated conditions.

[0017] Preferably, the molar ratio of the reducing agent in the agent for repairing hexavalent chromium contaminated soil in a one-step method to the hexavalent chromium in the hexavalent chromium contaminated soil is 4-16:1.

[0018] Further preferably, the molar ratio of the reducing agent in the agent for repairing hexavalent chromium contaminated soil in a one-step method to the hexavalent chromium in the hexavalent chromium contaminated soil is 6-12:1.

[0019] Still further preferably, the molar ratio of the reducing agent in the agent for repairing hexavalent chromium contaminated soil in a one-step method to the hexavalent chromium in the hexavalent chromium contaminated soil is 6-9:1.

[0020] Preferably, the water content of the hexavalent chromium contaminated soil is adjusted to 30%-40%.

[0021] Preferably, the curing under anaerobic or oxygen-isolated conditions is performed for 7-20 days.

[0022] Further preferably, the curing under anaerobic or oxygen-isolated conditions is performed for 12-15 days.

[0023] Preferably, the maintenance and repair is carried out under the condition of isolating oxygen.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The present application adds the reducing agent and the slightly soluble phosphate into the hexavalent chromium contaminated soil, because the phosphate is slightly soluble, the concentration of phosphate in the soil is low, and the reaction with the trivalent chromium ion produced by the reduction reaction is slow, so that the chromium phosphate crystal is obtained, and the stability is good, but because the phosphate is a slightly soluble salt, the migration property is poor, therefore, the crystallization modifier is added to improve the migration effect, and at the same time, because the crystallization modifier has a surface active group, the interface properties can be changed, the crystallization form of the chromium phosphate is improved, and the long-term stability of the chromium is realized. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The repair effect comparison chart of the hexavalent chromium contaminated soil of examples 10-11 and comparative example 3. DETAILED DESCRIPTION

[0027] Example 1

[0028] Take 200g of air-dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428mg / kg, and the content of hexavalent chromium is 370mg / kg), add 0.7742g of calcium hydrogen phosphate, 1.6223g of sodium pyrosulfite, OP-10 and water, the addition amount of OP-10 is 10mg, and the addition amount of water is 60g, stir at room temperature for 30 minutes, seal and maintain for 14 days, take samples for analysis, detect the content of hexavalent chromium in the soil according to the “Solid Waste Determination of Hexavalent Chromium Alkaline Digestion / Flame Atomic Absorption Spectrophotometry” (i.e. HJ 687-2014), and the detection results are as follows: the content of hexavalent chromium in the soil is 0.34mg / kg, the concentration of chromium element in the soil leaching liquid (total chromium leaching) is 0.12mg / kg according to the Appendix D of the “Hazardous Waste Identification Standard Leaching Toxicity Identification” (i.e. GB 5085.3-2007) and the “Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method” (i.e. HJ / T 299-2007), and the concentration of hexavalent chromium (hexavalent chromium leaching) in the soil leaching liquid is ND (not detected) according to the “Solid Waste Determination of Hexavalent Chromium Diphenyl Carbazide Spectrophotometry” (i.e. GB / T 15555.4-1995) and the “Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method” (i.e. HJ / T 299-2007).

[0029] The repaired soil is placed in the open air for 90 days, and the sample detection results are as follows: the content of hexavalent chromium in the soil is 0.23mg / kg, the total chromium leaching is 0.17mg / kg, and the hexavalent chromium leaching is 0.05mg / kg, which meets the requirements of Tables 3-5 of HJ / T 301-2007 for comprehensive utilization of chromium contaminated soil.

[0030] Example 2

[0031] Take 200g of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428mg / kg, the content of hexavalent chromium is 370mg / kg), add 0.7742g of calcium hydrogen phosphate, 3.0738g of glucose, OP-10 and water, the addition amount of OP-10 is 10mg, the addition amount of water is 60g, stir for 30 minutes at room temperature, seal and maintain for 14 days, sample analysis gets the content of hexavalent chromium in soil is 0.62mg / kg, the total leaching chromium is 0.13mg / kg, the leaching hexavalent chromium is 0.05mg / kg. The repaired soil is placed in the open air for 90 days, sample detection gets the content of hexavalent chromium in soil is 1.22mg / kg, the total leaching chromium is 0.19mg / kg, the leaching hexavalent chromium is 0.11mg / kg, which reaches the requirements of HJ / T 301-2007 table 3~5 for comprehensive utilization of chromium contaminated soil.

[0032] Example 3

[0033] Take 200g of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428mg / kg, the content of hexavalent chromium is 370mg / kg), add 0.7742g of calcium hydrogen phosphate, 3.0738g of glucose, OP-10 and water, the addition amount of OP-10 is 10mg, the addition amount of water is 60g, stir for 30 minutes at room temperature, seal and maintain for 14 days, sample analysis gets the content of hexavalent chromium in soil is 0.62mg / kg, the total leaching chromium is 0.13mg / kg, the leaching hexavalent chromium is 0.05mg / kg. The repaired soil is placed in the open air for 90 days, sample detection gets the content of hexavalent chromium in soil is 1.22mg / kg, the total leaching chromium is 0.19mg / kg, the leaching hexavalent chromium is 0.11mg / kg, which reaches the requirements of HJ / T 301-2007 table 3~5 for comprehensive utilization of chromium contaminated soil.

[0034] Example 4

[0035] Take 200g of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428mg / kg, the content of hexavalent chromium is 370mg / kg), add 0.7742g of calcium hydrogen phosphate, 3.0738g of glucose, OP-10 and water, the addition amount of OP-10 is 10mg, the addition amount of water is 60g, stir for 30 minutes at room temperature, seal and maintain for 14 days, sample analysis gets the content of hexavalent chromium in soil is 0.62mg / kg, the total leaching chromium is 0.13mg / kg, the leaching hexavalent chromium is 0.05mg / kg. The repaired soil is placed in the open air for 90 days, sample detection gets the content of hexavalent chromium in soil is 1.22mg / kg, the total leaching chromium is 0.19mg / kg, the leaching hexavalent chromium is 0.11mg / kg, which reaches the requirements of HJ / T 301-2007 table 3~5 for comprehensive utilization of chromium contaminated soil.

[0036] Example 5

[0037] 100 kg of air-dried hexavalent chromium contaminated soil (wherein the total chromium content is 4428 mg / kg, and the hexavalent chromium content is 114 mg / kg), 119 g of calcium hydrogen phosphate, 150 g of sodium pyrosulfite, 214 g of glucose, 10 g of OP-10 are added, 30 kg of water is added, stirring for 30 minutes, sealed and cured for 7 days, sampling and detecting the hexavalent chromium content in the soil, the result is ND, the total chromium leaching is 0.07 mg / kg, and the hexavalent chromium leaching is 0.03 mg / kg. The repaired soil is naturally placed in the open air for 150 days, and sampling and detection are performed to obtain the hexavalent chromium content in the soil of 1.23 mg / kg, the total chromium leaching of 0.08 mg / kg, and the hexavalent chromium leaching of 0.04 mg / kg, which meets the comprehensive utilization requirements of chromium contaminated soil in Tables 3-5 of HJ / T 301-2007.

[0038] Example 6

[0039] 100 kg of air-dried hexavalent chromium contaminated soil (wherein the total chromium content is 4428 mg / kg, and the hexavalent chromium content is 114 mg / kg), 119 g of calcium hydrogen phosphate, 150 g of sodium pyrosulfite, 214 g of glucose, 10 g of OP-10 are added, 30 kg of water is added, stirring for 30 minutes, sealed and cured for 7 days, sampling and detecting the hexavalent chromium content in the soil, the result is ND, the total chromium leaching is 0.07 mg / kg, and the hexavalent chromium leaching is 0.03 mg / kg. The repaired soil is naturally placed in the open air for 150 days, and sampling and detection are performed to obtain the hexavalent chromium content in the soil of 1.23 mg / kg, the total chromium leaching of 0.08 mg / kg, and the hexavalent chromium leaching of 0.04 mg / kg, which meets the comprehensive utilization requirements of chromium contaminated soil in Tables 3-5 of HJ / T 301-2007.

[0040] Example 7

[0041] 100 kg of air-dried hexavalent chromium contaminated soil (wherein the total chromium content is 4428 mg / kg, and the hexavalent chromium content is 114 mg / kg), 119 g of calcium hydrogen phosphate, 150 g of sodium pyrosulfite, 214 g of glucose, 10 g of OP-10 are added, 30 kg of water is added, stirring for 30 minutes, sealed and cured for 7 days, sampling and detecting the hexavalent chromium content in the soil, the result is ND, the total chromium leaching is 0.07 mg / kg, and the hexavalent chromium leaching is 0.03 mg / kg. The repaired soil is naturally placed in the open air for 150 days, and sampling and detection are performed to obtain the hexavalent chromium content in the soil of 1.23 mg / kg, the total chromium leaching of 0.08 mg / kg, and the hexavalent chromium leaching of 0.04 mg / kg, which meets the comprehensive utilization requirements of chromium contaminated soil in Tables 3-5 of HJ / T 301-2007.

[0042] In the soil remediation process, the added calcium dihydrogen phosphate will react to form calcium hydrogen phosphate, and so on.

[0043] Example 8

[0044] 100 kg of dried hexavalent chromium contaminated soil (wherein the total chromium content is 4428 mg / kg, and the hexavalent chromium content is 500 mg / kg), 446 g of calcium dihydrogen phosphate, 10 g of OP-10, 30 kg of water are added, stirred uniformly, 875 g of sodium pyrosulfite and 1250 g of glucose are added, stirred for 30 minutes, sealed and cured for 7 days, sampling analysis shows that the hexavalent chromium content in the soil is 7.66 mg / kg, the total chromium leaching is 0.15 mg / kg, and the hexavalent chromium leaching is 0.08 mg / kg. The remediated soil is left in the open air for 150 days, and the hexavalent chromium content in the soil is detected by sampling, the results are ND, the total chromium leaching is 0.14 mg / kg, and the hexavalent chromium leaching is 0.08 mg / kg, which meets the comprehensive utilization requirements of chromium contaminated soil in Tables 3-5 of HJ / T 301-2007.

[0045] Example 9

[0046] 10000 kg of dried hexavalent chromium contaminated soil (wherein the total chromium content is 4428 mg / kg, and the hexavalent chromium content is 114 mg / kg), 7.5 kg of calcium dihydrogen phosphate is added, 200 kg of water and 250 g of OP-10 are added, stirred for 30 minutes, 7.5 kg of sodium pyrosulfite and 9.5 kg of glucose are added, 150 kg of water is added, sealed and cured for 7 days, sampling analysis shows that the hexavalent chromium content in the soil is ND, the total chromium leaching is 0.11 mg / kg, and the hexavalent chromium leaching is 0.076 mg / kg. The remediated soil is left in the open air for 150 days, and the hexavalent chromium content in the soil is detected by sampling, the results are ND, the total chromium leaching is 0.17 mg / kg, and the hexavalent chromium leaching is 0.095 mg / kg, which meets the comprehensive utilization requirements of chromium contaminated soil in Tables 3-5 of HJ / T 301-2007.

[0047] Example 10

[0048] Take 200 g of dried hexavalent chromium contaminated soil (wherein the total chromium content is 4428 mg / kg, and the hexavalent chromium content is 370 mg / kg), add 0.6489 g of sodium pyrosulfite, 1.8443 g of glucose, 0.7742 g of calcium hydrogen phosphate, 60 g of water, add 100 mg of OP-10, the temperature is normal temperature, stir for 30 minutes, seal and cure for 14 days, sampling analysis of the hexavalent chromium content in the soil shows that the results are Figure 1 , which meets the comprehensive utilization requirements of chromium contaminated soil in Tables 3-5 of HJ / T 301-2007.

[0049] Example 11

[0050] Take 200g of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428mg / kg, the content of hexavalent chromium is 370mg / kg), add 0.6489g of sodium pyrosulfite, 1.8443g of glucose, 0.7742g of calcium hydrogen phosphate, 60g of water, add 100mg of JFC-2, the temperature is normal temperature, stir for 30 minutes, seal and maintain for 14 days, take sample to analyze the content of hexavalent chromium in the soil, the results are shown in Figure 1 , which meets the requirements of chromium contaminated soil comprehensive utilization in Table 3-5 of HJ / T 301-2007.

[0051] Comparative Example 1

[0052] 100kg of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428mg / kg, the content of hexavalent chromium is 114mg / kg), add 166g of sodium pyrosulfite and 237g of glucose, 10g of OP-10, add water 16kg, stir for 30 minutes, then add 119g of calcium hydrogen phosphate, add water 14kg, stir for 30 minutes, seal and maintain for 7 days, sample analysis shows that the content of hexavalent chromium in the soil is 8.96mg / kg, the total chromium leaching is 0.47mg / kg, and the hexavalent chromium leaching is 0.037mg / kg. The repaired soil is placed in the open air for 150 days, and sample detection shows that the content of hexavalent chromium in the soil is 6.34mg / kg, the total chromium leaching is 0.33mg / kg, and the hexavalent chromium leaching is 0.18mg / kg.

[0053] Comparative Example 2

[0054] Take 200g of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428mg / kg, the content of hexavalent chromium is 1680mg / kg), add 7.3662g of sodium pyrosulfite and 80g of water, the temperature is normal temperature, seal and maintain for 14 days, sample analysis shows that the content of hexavalent chromium in the soil is 16.84mg / kg, the total chromium leaching is 1.25mg / kg, and the hexavalent chromium leaching is 0.38mg / kg. The repaired soil is placed in the open air for 90 days, and sample detection shows that the content of hexavalent chromium in the soil is 56.83mg / kg, the total chromium leaching is 23.22mg / kg, and the hexavalent chromium leaching is 6.33mg / kg.

[0055] Comparative Example 3

[0056] Take 200g of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428mg / kg, the content of hexavalent chromium is 370mg / kg), add 0.6489g of sodium pyrosulfite, 1.8443g of glucose, 0.7742g of calcium hydrogen phosphate, 60g of water, do not add crystallization modifier, the temperature is normal temperature, stir for 30 minutes, seal and maintain for 14 days, take sample to analyze the content of hexavalent chromium in the soil, the results are shown in Figure 1 .

[0057] Comparative Example 4

[0058] Take 200 g of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428 mg / kg, and the content of hexavalent chromium is 370 mg / kg), add 0.6489 g of sodium pyrosulfite, 1.8443 g of glucose, 0.7742 g of calcium hydrogen phosphate, 60 g of water, add 100 mg of JFC, the temperature is normal temperature, stir for 30 minutes, seal and maintain for 14 days, take sample analysis to obtain the content of hexavalent chromium in the soil is 14.06 mg / kg.

[0059] Comparative Example 5

[0060] Take 200 g of dried hexavalent chromium contaminated soil (wherein the total content of chromium element is 4428 mg / kg, and the content of hexavalent chromium is 370 mg / kg), add 0.8112 g of sodium pyrosulfite, 20 mg of OP-10, 60 g of water, 0.7742 g of calcium hydrogen phosphate, stir for 30 minutes, the temperature is normal temperature, seal and maintain for 14 days, take sample analysis to obtain the content of hexavalent chromium in the soil is 60.45 mg / kg, the total chromium leaching is 4.51 mg / kg, and the hexavalent chromium leaching is 2.18 mg / kg. The repaired soil is placed in the open air for 90 days, and sample detection is taken to obtain the content of hexavalent chromium in the soil is 58.76 mg / kg, the total chromium leaching is 3.48 mg / kg, and the hexavalent chromium leaching is 1.38 mg / kg.

[0061] Comparative analysis of the results of the above examples and comparative examples can obtain the following conclusions:

[0062] (1) Example 6 and Comparative Example 1 respectively adopt one-step method and two-step method, and the repair effect of hexavalent chromium contaminated soil is almost the same. However, Comparative Example 1 is only a pilot test, and the two-step method is more troublesome in engineering application, with long cycle, long repair equipment occupation period and high cost, especially for in-situ repair, after the completion of one-step reduction, the soil is in slurry state, and the mechanical equipment needs to be taken out, and it is difficult to inject the reagent for the second time. The one-step method of Example 6 not only has no such problems, but also can achieve the same repair effect as the two-step method, so the one-step method of the present scheme is better.

[0063] (2) Comparative Example 2 only adds a reducing agent, and Example 4 and Comparative Example 2 add a stabilizing agent and a crystallization modifier, and the content of hexavalent chromium in the repaired soil is lower, so the addition of the stabilizing agent and the crystallization modifier can promote the repair of the hexavalent chromium contaminated soil.

[0064] (3) Comparative Example 3 uses a reducing agent and a stabilizing agent, but does not use a crystallization modifier, and Examples 10-11 and Comparative Example 3 use a crystallization modifier, and achieve better repair effect of hexavalent chromium contaminated soil (such as Figure 1As shown in FIG. 6, it can be seen that the crystallization modifier can promote the remediation of hexavalent chromium contaminated soil.

[0065] (4) Compared with Comparative Example 4 and Examples 10-11, the crystallization modifier used is JFC, but the remediation effect on hexavalent chromium contaminated soil is poor, which shows that the remediation effect of JFC is not as good as that of OP-10 and JFC-2.

Claims

1. A one-step agent for remediating hexavalent chromium-contaminated soil, characterized in that, Including reducing agents, stabilizing agents, and crystallization modifiers; The reducing agent is at least one of sulfur-containing compounds and organic reducing agents with reducing properties; The crystallization modifier is at least one of OP-10 and JFC-2; The reducing sulfur-containing compound is at least one of sodium metabisulfite, sodium dithionite, sodium sulfite, potassium metabisulfite, potassium dithionite, and potassium sulfite. The organic reducing agent is at least one of glucose, ethanol, and ascorbic acid; The stabilizing agent is at least one of calcium hydrogen phosphate and magnesium hydrogen phosphate; The mass ratio of the reducing agent to the stabilizing agent is 2~5:1, and the mass ratio of the reducing agent to the crystallization modifier is 25~368:

1.

2. The agent for one-step remediation of hexavalent chromium contaminated soil according to claim 1, characterized in that, The mass ratio of the reducing agent to the stabilizing agent is 2~3:

1.

3. The application of the one-step remediation agent for hexavalent chromium contaminated soil according to any one of claims 1 to 2 in the removal of hexavalent chromium ions from soil.

4. A one-step method for remediating hexavalent chromium-contaminated soil, characterized in that, Includes the following steps: Add the agent for one-step remediation of hexavalent chromium-contaminated soil as described in any one of claims 1 to 2 to the hexavalent chromium-contaminated soil, adjust the moisture content of the hexavalent chromium-contaminated soil to 20% to 60%, then mix evenly, and carry out maintenance and remediation under anaerobic or oxygen-isolated conditions.

5. The one-step method for remediating hexavalent chromium-contaminated soil according to claim 4, characterized in that, The molar ratio of the reducing agent in the one-step remediation agent for hexavalent chromium-contaminated soil to the hexavalent chromium in the soil is 4~16:

1.

6. The one-step method for remediating hexavalent chromium-contaminated soil according to claim 5, characterized in that, The molar ratio of the reducing agent in the one-step remediation agent for hexavalent chromium-contaminated soil to the hexavalent chromium in the soil is 6~12:

1.

7. The one-step method for remediating hexavalent chromium-contaminated soil according to claim 4, characterized in that, Under conditions of oxygen deficiency or isolation, carry out maintenance and repair for 7 to 20 days.

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