CN-122007137-A - Hexavalent chromium pollution solid material treatment method and application thereof

Abstract

The invention discloses a treatment method of hexavalent chromium pollution solid material and application thereof, belonging to the technical field of environmental engineering. The method provides a green and efficient microwave enhanced repair scheme. The method comprises the steps of fully mixing hexavalent chromium polluted soil with a reducing material and a low-molecular-weight organic acid solution to form a mixed material to be repaired, and then carrying out microwave irradiation treatment on the mixed material to complete rapid deep repair. The invention promotes the release of insoluble hexavalent chromium by utilizing the protonation and complexation of the organic acid, and simultaneously remarkably improves the selectivity and the reduction capability of the reduction material to hexavalent chromium by means of local hot spot effect generated on the surface of the microwave absorbing reduction material, realizes the synergy of the microwave, the organic acid and the reduction material, has the remarkable advantages of high restoration speed, good reduction effect and the like, and is particularly suitable for the treatment of polluted soil and industrial waste residues with high concentration and insoluble hexavalent chromium compounds.

Inventors

• ZHAI XIAOFENG
• SI MENGYING
• LIAO QI
• ZHANG XIAOMING
• YANG WEICHUN
• XU HAO
• PING YANG
• ZHANG ZHENZHOU
• CHEN CHENYU
• YANG ZHIHUI
• LI QINGZHU

Assignees

• 中南大学
• 中电建生态环境集团有限公司

Dates

Publication Date

20260512

Application Date

20260203

Claims (10)

1. 1. The hexavalent chromium pollution solid material treatment method is characterized by comprising the following steps: mixing hexavalent chromium pollution solid materials, a reducing agent and a solvent promoter to obtain a mixture to be repaired; and the to-be-repaired mixed material is subjected to microwave irradiation treatment to obtain a microwave repair product.
2. 2. The method for treating hexavalent chromium pollution solid according to claim 1, wherein the mass-volume ratio of the hexavalent chromium pollution solid to the reducing agent to the dissolution accelerator in the mixture to be repaired is 1g (0.01-0.05 g) (0.5-10 ml).
3. 3. The method for treating hexavalent chromium-polluted solid material according to claim 2, wherein the mass-volume ratio of the hexavalent chromium-polluted solid material, the reducing agent and the dissolution promoter in the mixture to be repaired is 1g (0.01-0.05 g) (0.5-5 ml).
4. 4. The method for treating hexavalent chromium-contaminated solid material according to claim 1, wherein in the case where the proportion of water-soluble hexavalent chromium in the hexavalent chromium-contaminated solid material is less than 90% of the total hexavalent chromium, the dissolution promoter is an organic acid, the kind of the organic acid includes one or more of citric acid, tartaric acid and oxalic acid, and the concentration of the organic acid is not more than 0.5 mol/L; In the case where the water-soluble hexavalent chromium accounts for more than 90% of the total hexavalent chromium in the hexavalent chromium-contaminated solid material, the dissolution promoting agent includes water.
5. 5. The method for treating hexavalent chromium-contaminated solid material according to claim 1, wherein the reducing agent is one or more of acid-activated montmorillonite-loaded zero-valent iron sulfide, zero-valent iron sulfide or other reducing agents containing iron and sulfur and having microwave absorption characteristics.
6. 6. The method for treating hexavalent chromium pollution solid according to claim 1, wherein in the microwave irradiation treatment process, the power of microwave irradiation is 0.28-0.56 kW, and the microwave time is 1-10min.
7. 7. The method for treating hexavalent chromium polluted solid material according to claim 1, further comprising stabilizing the microwave-repaired product to obtain a solidified product; The stabilization treatment includes landfill.
8. 8. The method for treating hexavalent chromium-contaminated solid material according to claim 1, wherein the concentration of total hexavalent chromium in the hexavalent chromium-contaminated solid material is not lower than 1500 mg/kg, and the concentration of insoluble hexavalent chromium is not lower than 100 mg/kg, and the source of the hexavalent chromium-contaminated solid material includes at least one of chromium salt industrial waste, chromium-containing electroplating sludge, and hexavalent chromium-contaminated soil.
9. 9. The method for treating hexavalent chromium-polluted solid material as claimed in claim 1, wherein the dissolution rate of hexavalent chromium is greater than or equal to 99%, and the reduction rate of hexavalent chromium is greater than or equal to 99%.
10. 10. Use of the method for treating hexavalent chromium-contaminated solid material according to any of claims 1-9 in the remediation of hexavalent chromium-contaminated soil.

Description

Hexavalent chromium pollution solid material treatment method and application thereof Technical Field The invention belongs to the technical field of environmental engineering, and particularly relates to a treatment method of hexavalent chromium pollution solid materials and application thereof. Background Hexavalent chromium is used as a heavy metal pollutant with strong oxidability, high mobility and high toxicity, and forms a serious threat to human health and ecological environment. The polluted soil is alkaline, the pH value is generally 8-11, and the highest pH value is even more than 12, and the repair complexity is increased. The difficulty of repair is not only its toxicity, but also its morphological complexity and high heterogeneity in the soil medium. Hexavalent chromium in soil is commonly present in two forms, soluble hexavalent chromium, ionic or adsorbed, readily mobile and releasable, relatively easily contacted with a remediation agent and reduced, poorly soluble hexavalent chromium, compounds or precipitated, e.gAnd (3) withThe calcium chromate formed, or into the lattice of the layered double hydroxide structure. For severe hexavalent chromium-polluted soil, waste residue or sludge, the content of insoluble hexavalent chromium which is stable in combination and difficult to release can reach 10 2–103 mg/kg, which is far more than the conventional risk control standard. This constitutes a "contact barrier" in the repair, i.e. it is difficult for conventional agents to effectively contact and reduce this part of hexavalent chromium fixed by the mineral phase, resulting in incomplete repair, with the risk of secondary release upon a change in environmental conditions (e.g. a decrease in pH). However, when the existing wet chemical reduction-based technology is used for treating the high-concentration and polymorphic hexavalent chromium severely polluted soil, waste residue or sludge (for example, the total concentration of hexavalent chromium is not lower than 3000 mg/kg, and the concentration of insoluble hexavalent chromium is not lower than 100 mg/kg), core short plates with insufficient efficacy of repairing agents, difficulty in thoroughly breaking through a contact barrier, complex process flow, secondary pollution and the like generally exist. Therefore, developing a new technology capable of overcoming the above-mentioned drawbacks and realizing green, efficient, deep and stable repair has become an urgent need in the current environmental engineering field. Disclosure of Invention Aiming at solving the technical problems of insufficient medicament repairing efficiency, difficult complete breakthrough of a contact barrier, complex process flow and associated secondary pollution in the common technology, the invention provides a hexavalent chromium pollution solid material treatment method, which comprises the following steps: mixing hexavalent chromium pollution solid materials, a reducing agent and a solvent promoter to obtain a mixture to be repaired; and the to-be-repaired mixed material is subjected to microwave irradiation treatment to obtain a microwave repair product. Further, the mass volume ratio of hexavalent chromium pollution solid materials, reducing agent and solvent accelerator in the mixture to be repaired is 1g (0.01-0.05 g) (0.5-10 ml). Further, the mass volume ratio of hexavalent chromium pollution solid materials, reducing agent and solvent accelerator in the mixture to be repaired is 1g (0.01-0.05 g) (0.5-5 ml). Further, under the condition that the proportion of water-soluble hexavalent chromium in the hexavalent chromium-polluted solid material is less than 90% of the total hexavalent chromium, the cosolvent is an organic acid, the organic acid comprises one or more of citric acid, tartaric acid and oxalic acid, and the concentration of the organic acid is not higher than 0.5 mol/L; In the case where the hexavalent chromium-contaminated solid material has a proportion of water-soluble hexavalent chromium to total hexavalent chromium of more than 90%, the dissolution promoting agent includes water. Further, the reducing agent is one or more of acid activated montmorillonite loaded with zero-valent iron sulfide, zero-valent iron sulfide or other reducing agents containing iron and sulfur and having microwave absorption characteristics. Further, in the microwave irradiation treatment process, the power of microwave irradiation is 0.28-0.56 kW, and the microwave time is 1-10min. Further, the method further comprises the step of stabilizing the microwave repair product to obtain a cured product; The stabilization treatment includes landfill. Further, the concentration of the total hexavalent chromium in the hexavalent chromium-polluted solid material is not lower than 1500 mg/kg, and the concentration of insoluble hexavalent chromium is not lower than 100 mg/kg, and the source of the hexavalent chromium-polluted solid material comprises at least one of chromium sa