CN113695380A

CN113695380A - Electrode system device for repairing soil heavy metal pollutants

Info

Publication number: CN113695380A
Application number: CN202111041288.3A
Authority: CN
Inventors: 吴卿; 叶群颖; 彭森
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2021-09-07
Filing date: 2021-09-07
Publication date: 2021-11-26

Abstract

The invention discloses an electrode system device for repairing soil heavy metal pollutants, which comprises a laboratory, an electrode chamber, a migration chamber, an interlayer, a direct current power supply and the like. The electrode system, the electrode chamber and the migration chamber are separated by an interlayer, and a and f are the electrode chambers; and b, c, d and e4 electrode chambers are transfer chambers. The migration chamber is tamped by 2.0-4.0 kg of soil polluted by Cr (VI), and two sides of the migration chamber are respectively placed in 300-500 g of chromium-free soil. The dc power supply and the electrodes were connected by wires, and the electrodes provided a stable electric field, which was a plate-shaped high purity graphite electrode having a size of 100mm × 10mm × 100mm and embedded in uncontaminated soil. The laboratory was made of polymethyl methacrylate. The invention takes chromium salt polluted soil as a representative heavy metal pollutant, and the invention is an innovative technology for economically and effectively degrading heavy metal pollution of soil.

Description

Electrode system device for repairing soil heavy metal pollutants

Technical Field

The invention belongs to the technical field of waste treatment and disposal, and particularly relates to an electrode system device for repairing soil heavy metal pollutants.

Background

The increased concentrations of heavy metals such As Cr, As, Hg and Cu in soils resulting from improper disposal of industrial and municipal activities pose potential threats to the environment and human health. Among these heavy metals, chromium is one of the most difficult heavy metals to remove from contaminated soil, and hexavalent chromium, cr (vi), has 500 times the toxicity of trivalent chromium.

Electrokinetic remediation is a promising and inexpensive in situ remediation technique for removing heavy metals from soil. By inserting electrodes into the soil to create a low direct current or low potential gradient, contaminants in the soil can propagate due to electromigration, electrophoresis, electroosmosis, and diffusion. In this process, electromigration is an important process with respect to the migration of ionic chemicals due to an electric field, and then concentration of heavy metal contaminants by an electrode system device. Electrokinetic remediation is highly efficient and time efficient in treating contaminated low permeability soils.

In this process, the application of an electric field to the soil causes the charged metal species to move towards the electrode compartment for removal, while the main removal efficiency of the heavy metals depends mainly on the influence on the ionic components present in the soil. The form and concentration of the ions depend on different chemical processes including adsorption and desorption, precipitation and dissolution and oxidation and reduction of heavy metals in the soil, which are the migration and conversion processes of heavy metal components. Electrokinetic systems that employ composite materials in electrode systems for treating heavy metal contaminated soil are of practical interest.

Disclosure of Invention

The invention relates to an electrode system device for repairing soil heavy metal pollutants, which comprises a direct current power supply lead, a graphite electrode migration layer, a laboratory, a graphite electrode, an interlayer and uncontaminated soil, wherein the electrode is inserted into the soil to generate low direct current or low potential gradient, so that the pollutants in the soil are spread due to electromigration, electrophoresis, electroosmosis and diffusion.

Fig. 1 shows a schematic diagram of an electrode repair experimental apparatus used in the present study. The laboratory is made of polymethyl methacrylate, the volume is 3-6L, the central chamber is divided into four areas S1, S2, S3 and S4, and 2.0-4.0 kg of soil polluted by Cr (VI) is tamped. The two sides of the central chamber are respectively placed in the chromium-free soil. The graphite electrode provides a stable electric field, which is a plate-shaped high purity graphite electrode having a thickness of 100mm x 10mm x 100mm, and is embedded in contaminated soil. Two rod-like graphite electrodes (100 mm. times.10 mm. times.100 mm) were placed in the anode chamber and the cathode chamber, respectively, and connected to the positive electrode and the negative electrode of a power supply, respectively. The interlayer in the electrode chamber is close to the electrode, is a permeable reactive barrier and is packaged in nylon fabric to isolate soil particles. The pH value of the soil of the migration layer is 0.1M KOH and 0.1M H₂SO₄And (4) regulating the concentration. The cathode, the anode and the direct current power supply are connected through leads. Deionized water was used as the background electrolyte solution in the transfer chamber to ensure that the moisture content of the system was 30% to 40%. Using the said to remediate heavy metals in soilAfter the electrode system device of the pollutant is used for processing, the soil sample is taken out of the processing chamber and is evenly divided into four parts from the anode to the cathode (S1-S4), so that the spatial distribution trend of the polluted metal after processing can be visually displayed, and the recovery influence can be directly reflected.

Drawings

FIG. 1 is a schematic diagram of a repair experiment apparatus

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention relates to an electrode system device for repairing soil heavy metal pollutants, which comprises a direct current power supply lead, a graphite electrode, a migration layer, a laboratory, a graphite electrode, an interlayer and uncontaminated soil. Before the experiment, the components of the electrokinetic reactor were soaked in dilute acid solution for 24h and then rinsed with tap water and deionized water to avoid cross-contamination between experiments.

For each electrokinetic experiment, the area in each soil chamber was filled with 2.0-4.0 kg of Cr-contaminated soil (dry weight) and the electrode area was filled with 300-500 g (dry weight) of Cr-free soil to investigate whether Cr penetrated the permeable reactive barrier. 200g of humus was added to the contaminated soil and mixed thoroughly. Then, 0.2 liters of bacterial culture was injected directly into the soil cells to ensure uniform distribution. Deionized water was used as the sole background electrolyte solution to ensure that the moisture content of the system was 40%. The power supply was turned on and a constant voltage of 24V (1V/cm) was applied between the two electrodes using a dc power supply, since a voltage gradient of 1V/cm was considered to be cost-effective.

After the test is finished for 1-3 h, taking out the soil sample from the treatment chamber, and averagely dividing the soil sample into four parts (S1-S4) from the anode to the cathode, thus visually displaying the spatial distribution trend of the treated polluted metal, directly reflecting the influence on recovery, analyzing the pH, current density and Cr of the soil sample⁶⁺Concentration and total Cr concentration.

The foregoing is only a preferred embodiment of this invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the invention and should be considered as within the scope of the invention.

Claims

1. The invention discloses an electrode system device for repairing soil heavy metal pollutants, which comprises a laboratory, an electrode chamber, a migration chamber, an interlayer, a direct current power supply and the like. It is characterized in that the electrode chamber and the migration chamber are separated by an interlayer, and a and f are the electrode chambers; the b, c, d, e4 electrode chambers are migration chambers. The migration chamber is tamped by 2.0-4.0 kg of soil polluted by Cr (VI), and two sides of the migration chamber are respectively placed in 300-500 g of chromium-free soil.

2. The electrode system device for remediating soil heavy metal pollutants as recited in claim 1, wherein the laboratory is made of polymethyl methacrylate and has a volume of 3-6L.

3. The electrode system device for remediating heavy metal pollutants in soil as claimed in claim 1, wherein each of the soil chambers b, c, d, e is filled with 2.0-4.0 kg of Cr-contaminated soil (dry weight).

4. The electrode system device for remediating heavy metal pollutants in soil as recited in claim 1, wherein the chambers a and f are filled with 300g to 500g of chromium-free soil.

5. The electrode system device for remediating heavy metal pollutants in soil as recited in claim 1, wherein the pH value of the soil between the electrodes is in a range of 6.0 to 9.0.

6. The electrode system device for remediating soil heavy metal pollutants as claimed in claim 1, wherein the direct current power supply and the electrode are connected by a lead, the lead is made of copper and has a length of 25-30 cm.

7. The electrode system device for remediating heavy metal pollutants in soil as claimed in claim 1, wherein the electrode provides a stable electric field, and the electrode is a plate-shaped high-purity graphite electrode with a thickness of 100mm x 10mm x 100 mm.

8. The electrode system apparatus for remediating heavy metal contaminants of soil as recited in claim 1, wherein said graphite electrode is coupled to said interlayer to isolate soil particles.

9. The electrode system device for remediating soil heavy metal pollutants as claimed in claim 1, wherein b, c, d, and e are migration chambers, wherein the sample inlet is positioned above the center of the migration chambers, and wherein 200g of humus is added to the polluted soil and mixed thoroughly.