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Method of electrodynamics for restoring soil polluted by heavy metal

A technology of polluted soil and electrokinetics, applied in electrokinetic remediation, using ion exchange membranes to assist electrokinetics in the field of remediation of polluted soils, can solve the negative impact on the safety of soil ecosystems, the limited adsorption capacity of carbonate adsorption layers, and limited popularization and application and other problems, to achieve the effect of increasing migration speed, convenient operation, and improving removal efficiency

Inactive Publication Date: 2005-11-16
SHANGHAI JIAO TONG UNIV
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Problems solved by technology

U.S. Patent No. 20020013506 disclosed on January 31, 2002 adopts electrokinetic method to treat polluted soil, and adopts an ion-exchange membrane-assisted electrokinetic method to remove pollutants (mainly organic pollutants) in soil, although it is useful for removing heavy metals in soil A certain effect (need to add a large amount of chemical reagents), which will have a negative impact on the safety of the soil ecosystem; moreover, the OH produced by electrolysis - Underutilized, thus limiting the application of the technology
Korean patent KR2003068697-A published on August 25, 2003 avoids OH by placing a carbonate adsorption layer on the cathode side - Entering the treatment area, the disadvantage of this method is that the adsorption capacity of the carbonate adsorption layer is limited, and it is easy to cause secondary pollution

Method used

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  • Method of electrodynamics for restoring soil polluted by heavy metal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Embodiment 1 adopts such as figure 1 The shown device performs soil electrokinetic remediation treatment. The electrolytic cell 1 is an open container and placed horizontally. The cathode chamber 2 and the anode chamber 3 are respectively arranged at both ends of the electrolytic cell 1 . The cathode 4 is placed in the cathode chamber 2 and the anode 5 is placed in the anode chamber 3 . The cation exchange membrane 6 is placed between the cathode chamber 2 and the electrolytic cell 1 , and the porous ceramic plate 7 is placed between the ion exchange membrane 6 and the soil in the electrolytic cell 1 . The positive pole of the stabilized DC power supply 9 is connected to the anode 5 through wires, and the negative pole is connected to the cathode 4 . The catholyte buffer tank 10 and the anolyte buffer tank 11 communicate with the cathode chamber 2 and the anode chamber 3 respectively through the engineering plastic pipe delivery pump 12 . The ratio of the volume of th...

Embodiment 2

[0025] The structure of the repairing device adopted is the same as in Example 1, and the ratio of the volume of the cathode chamber and the anode chamber to the volume of the electrolytic cell is 1:20. Weigh about 1000g simulated polluted soil sample, in which the cadmium concentration is about 100mg / kg, and use PbO 2 The / Ti electrode is the anode, and the graphite is the cathode; the cathode chamber and the soil sample are separated by a sulfonic acid type homogeneous cation exchange membrane, and the hourly circulation flow rate of the electrolysis buffer to the corresponding electrode chamber volume volume ratio is 0.01. The electrolysis buffer uses oxalic acid-sodium oxalate buffer solution with 2.5mol / l and pH value of 4; the constant voltage is 2V, the corresponding electric field strength is 0.2V / cm; It shows that the cadmium content in the soil sample is reduced to 0.50mg / kg. After the test, white Cd(OH) with a purity of 80.6% was separated in the cathode chamber 2...

Embodiment 3

[0027]The structure of the repairing device adopted is the same as in Example 1, and the ratio of the volume of the cathode chamber and the anode chamber to the volume of the electrolytic cell is 1:10. The simulated polluted soil with a lead content of about 100mg / kg was treated, and graphite electrodes were used as electrodes; the cathode chamber was separated from the soil sample by a sulfonic acid type homogeneous cation exchange membrane; The chamber volume to volume ratio was 0.2. The electrolytic buffer solution is acetic acid-sodium acetate buffer solution with 0.5mol / l and pH value of 3; the constant voltage is 15V, and the corresponding electric field strength is 1.5V / cm; It shows that the lead content in the soil sample is reduced to 0.46mg / kg. Qualitative analysis of the sediment in the cathode chamber shows that its main component is lead hydroxide, and Pb(OH) 2 Has very low solubility (dissolution constant is 1.2×10 -15 ) to obtain Pb(OH) with a purity of 85% b...

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Abstract

An electrodynamic method for repairing the soil polluted by heavy metal includes using ion exchange film to isolate cathode from said soil, inserting porous ceramic between said film and soil, controlling the pH value of soil by the H and OH ions generated by electrodes themsolves for speeding up the extraction of pollutants, depositing heavy metals in cathode solution, centrifugal purifying to obtain heavy metal compound, and using clean cathode solution to neutralizing soil.

Description

technical field [0001] The invention relates to an electrokinetic restoration method for heavy metal-contaminated soil, in particular to a method for electrokinetic restoration of polluted soil assisted by ion-exchange membranes, which is used for the treatment of soil heavy metal pollution and resource recovery, and belongs to the technical field of environmental protection and energy saving. Background technique [0002] According to reports, the area of ​​cultivated land polluted by heavy metals such as cadmium, arsenic, and lead in my country is nearly 20.0×10 3 km 2 , accounting for about 1 / 5 of the total arable land area; among them, 10.0×10 industrial “three wastes” polluted arable land 3 km 2 , the area of ​​farmland irrigated by sewage has reached 3.3×10 3 km 2 , The economic loss caused by various soil pollution is huge. Just taking heavy metal pollution in soil as an example, over 10 million tons of grain are reduced every year due to heavy metal pollution ac...

Claims

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Application Information

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IPC IPC(8): B09C1/00
Inventor 申哲民陈学军句炳新吴旦王文华
Owner SHANGHAI JIAO TONG UNIV
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