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Enhanced electrokinetic remediation method of heavy metal contaminated soil

A technology of polluted soil and electric remediation, applied in the restoration of polluted soil and other directions, can solve the problems of difficult dissolution of heavy metals and insufficient removal rate, and achieve the effects of shortening remediation time, improving removal efficiency, and high-efficiency removal effect.

Active Publication Date: 2012-07-04
上海环境保护有限公司
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  • Summary
  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

[0027] However, in the applicant's above-mentioned application, the pH values ​​of the cathode and anode are all controlled, especially the pH value of the anode is not low enough, which makes it necessary for Pb(II), Cr(III) and the like to be produced in a low pH environment. Dissolved heavy metals are difficult to dissolve, resulting in insufficient removal rate

Method used

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  • Enhanced electrokinetic remediation method of heavy metal contaminated soil
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  • Enhanced electrokinetic remediation method of heavy metal contaminated soil

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preparation example Construction

[0070] The preparation of the permeable reaction composite electrode of the present invention and the method for using it to carry out electrokinetic restoration of heavy metal polluted soil comprise the following steps:

[0071] (1) Fabrication of composite electrodes

[0072] Fe 0 : Powder with particle size of 10, 50, 100, 200, 400, 600 or 1000 mesh.

[0073] Basic zeolite: basic zeolite with a particle size of 10, 50, 100, 200, 400, 600 or 1000 mesh, the basic zeolite is NaX, NaY, NaM, NaA or NaZSM-5, or KF in Al 2 o 3 ·Basic zeolite formed by loading and modifying on 2NaY composite material. These zeolites have a pH of 8-14, preferably 14.

[0074] Acidic zeolite: Acidic zeolite with a particle size of 10, 50, 100, 200, 400, 600 or 1000 mesh, which is any acidic natural zeolite, or natural zeolite and the above-mentioned basic zeolite after acidification. Taking the phosphoric acidification of clinoptilolite as an example, with 10% by weight of H 3 PO 4 The aqueous...

Embodiment 1

[0088] Embodiment 1: Remediation of chromium-contaminated soil

[0089] A columnar composite electrode is used to electrodynamically remediate chromium-contaminated soil with a chromium (VI) content of 120.1 mg / kg and a moisture content of 30% by mass. Composite electrodes were composed of graphite electrode plates and different permeable reaction materials, and three groups of tests (A, B, and C) were carried out (as shown in Table 1 below). The cathode and anode are respectively high-purity graphite electrodes, and the basic zeolite in the active material is selected from NaX zeolite (initial pH value is 12), and the acid zeolite is formed by acidifying clinoptilolite with 10% phosphoric acid [mass concentration, the same below]. The particle size of the two zeolites is 30 mesh, and the selected Fe 0 The particle size is 300 mesh, these two zeolites and Fe 0 The mass ratio is 1:1. The distance between the cathode and anode electrodes is 20cm.

[0090] Apply a DC voltage ...

Embodiment 2

[0096] According to comprehensive analysis, the removal rates of chromium (VI) in tests A, B, and C all reached more than 90%, while the removal rate of total chromium in test A was much better than that of tests B and C, that is, the removal effect of the anode without pH control was the best. Embodiment 2: the remediation of lead, nickel, cadmium, copper polluted soil

[0097] Insert the columnar composite electrode into the soil with a moisture content of 30% by mass and heavy metal lead, nickel, cadmium, and copper contents of 82.4, 78.9, 85.6, and 86.9 mg / kg in a regular hexagonal matrix. The middle electrode is the cathode, and the cathode 1. The anode distance is 40cm, and a DC voltage with a voltage gradient of 1.5V / cm is applied, and the electric repair is performed for 10 days. The composite electrodes listed in the following table 2 were respectively selected for six groups of tests A, B, C, D, E, and F. In the experiments of groups E and F, the "saturated" composit...

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Abstract

The invention relates to an electrokinetic remediation method of heavy metal contaminated soil by using a composite electrode. According to the invention, an active material layer is adhered to the surface of a graphite electrode or a metal electrode with an anode and a cathode so as to form an integrated composite electrode with permeable reactive performance; on one hand, a cathode permeable reactive layer is used for neutralizing and adsorbing OH- generated by electrode reaction, avoiding the increase of pH value of cathode soils and further preventing heavy metals from depositing in the soils untimely; on the other hand, cathode permeable reactive layer is used for capturing the migrated heavy metal pollutants. The permeable reactive materials of the anode are mainly used for capturing the migrated heavy metal ions, an acid migration area generated by anode electrolytic reaction enters into the soil so as to dissolve out most heavy metals, the heavy metals are migrated into the anode and cathode permeable reactive materials under the action of an electrodynamic force, and in-situ removal of the heavy metal pollutants in the soil can be realized by the removing electrode. Afterremediation, the anode and the cathode are exchanged to balance the pH value of the soil.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, and in particular relates to the technical field of repairing heavy metal polluted soil by using an electric method. Background technique [0002] With the process of industrialization and urbanization in our country, the problem of soil heavy metal pollution has begun to appear. According to the survey of the national sewage irrigation area by the Ministry of Agriculture of my country, in the sewage irrigation area of ​​about 1.4 million hectares, the land area polluted by heavy metals accounts for 64.8% of the sewage irrigation area. Soil pollution is extremely harmful. Every year, 12 million tons of grains are polluted by heavy metals nationwide, causing direct economic losses of more than 20 billion yuan. Especially in the process of urbanization, the problem of heavy metal pollution sites left over from history has become more prominent, posing threats to the ecological env...

Claims

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Application Information

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IPC IPC(8): B09C1/00B09C1/08
Inventor 付融冰刘芳马晋张长波
Owner 上海环境保护有限公司
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