CN101138767A - Method for renovating soil polluted by heavy metal - Google Patents

Abstract

The present invention discloses a method of repairing soil polluted by heavy metal. Procedures of repair method are as following: (1) both sides of the soil are provided with electrode wells. Parallel negative electrode and positive electrode are installed in the electrode well, spaced at 0.1 to 1m. When the positive electrode adopts iron or aluminum, the negative electrode adopts manganese dioxide, carbon or copper; when the positive electrode adopts the carbon, the negative electrode adopts manganese dioxide; (2) the electrode well is filled with flushing fluid whose level is higher than that of the soil, thus, making materials of the negative and positive electrodes soaked in the flushing liquid; the flushing liquid is water or acid solution whose concentration is less than 2mol/l; (3) the negative and positive electrodes are connected and conduction time lasts for 30 to 500 days. The present invention makes negative and positive electrodes made up of different materials to have electrode reaction resulting from electrode potential of electrode surface, thus, forming primary batteries to produce potential difference to have pollutants in the soil between the negative and positive electrodes remove. Therefore, requirement for high consumption of additional power can be prevented. The method has advantages of low consumption, environment-friendly, good treatment effect and easy operation.

Description

A kind of restorative procedure of heavy-metal contaminated soil

Technical field

The invention belongs to the soil remediation technical field, be specifically related to a kind of restorative procedure of heavy-metal contaminated soil.

Technical background

Along with the development of industrial and agricultural production, a large amount of heavy metal contaminants enter into environment, and finally are accumulated in the soil, make soil pollution more and more serious.The direct economic loss that the agricultural product that the annual production of China contains heavy metal cause reaches 20,000,000,000 yuan, and problem is very serious.Soil pollution has become one of major obstacles of restriction agricultural products in China international trade and social sustainable development, and contaminated soil is badly in need of repairing.

Present contaminated soil recovery technique mainly comprises soil replacement method, burning method, solvent drip washing, steam extraction, chemical oxidation and biological treatment (comprising plant treatment) etc.Soil replacement method and burning method all have bigger consumption to manpower and materials.Biological treatment requires substance to be processed to have bioavailability preferably, requires to have the bacterial classification of high selectivity.Additive method requires processed soil to have permeability preferably.Electrodynamics soil remediation technology is a kind of method that develops at hyposmosis clayed soil specially, utilizes effects such as electromigration and electrodialysis that pollutant is moved from soil, realizes the reparation of contaminated soil.

Yet, traditional a large amount of electric energy of electrodynamics soil remediation Technology Need consumption, according to external authoritative institution statistics, the direct power consumption of repairing every necromancer earth is about about 100 dollars.In addition, this technology can damage soil when removing pollutant in soil, as makes the soil acidification of anode region and make the alkalization of soils in cathodic region.The factor of this two aspect, particularly high energy consumption has directly limited the actual through engineering approaches of electrodynamics technology and has used.Therefore, reduce the electric energy loss of electrodynamics technology, reduce simultaneously the destruction of handling soil region is necessary.

Summary of the invention

The objective of the invention is to overcome the deficiency of existing electrodynamics soil remediation technology, a kind of restorative procedure of heavy-metal contaminated soil is provided, this method is consumed power not, and is very little to the destruction of soil, has the low and eco-friendly advantage of operating cost.

The restorative procedure of heavy-metal contaminated soil provided by the invention the steps include:

(1) on pending soil both sides electrode wells is set, the yin, yang electrode is installed in the electrode wells, the parallel placement of electrode, electrode spacing is 0.1-1m; When anode material adopted iron or aluminium, negative electrode adopted manganese dioxide, carbon or copper; When anode material adopted carbon, negative electrode adopted manganese dioxide;

(2) in above-mentioned electrode wells, fill flushing liquor, make the liquid level of electrode wells be higher than processing soil height, and the cathode and anode material is immersed in the flushing liquor; Flushing liquor is water or the concentration acid solution smaller or equal to 2mol/L, and acid is sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, ethylenediamine tetra-acetic acid or citric acid;

(3) connect cathode and anode, conduction time is between 30-500 days.

The inventive method uses materials with different properties (as iron and carbon) to serve as anode and cathode, make the electrode reaction that different electrode potentials take place electrode surface constitute galvanic cell, thereby produce the migration that potential difference drives pollutant in soil between anode and cathode, avoided the required high energy consumption of additional power source.This method can also realize the increase of potential difference by the series connection of a plurality of galvanic cells, thereby improves treatment effect.Compare with traditional electrodynamics technology, this galvanic cell soil remediation technology is consumed power not, and is very little to the destruction of soil, has the low and environmental friendliness advantage of operating cost.In a word, the inventive method has advantages such as safe and reliable and easy and simple to handle, has the value of application.

Description of drawings

Fig. 1 is a principle schematic of the present invention.

Fig. 2 is the soil remediation installation drawing of single galvanic cell.

Fig. 3 is the soil remediation installation drawing of a plurality of galvanic cell series connection.

Fig. 4 is the treatment effect of galvanic cell technology to copper polluted soil.

Fig. 5 is the treatment effect of galvanic cell technology to cadmium pollution soil.

The specific embodiment

The electric field that the inventive method produces by galvanic cell drives heavy metal contaminants and moves from soil, reaches the reparation of contaminated soil.As shown in Figure 1, use materials with different properties to serve as anode and cathode on the both sides of contaminated soil, connect anode and cathode with lead and constitute galvanic cell, drive the inorganic ions generation electromigration in the contaminated soil, cation is to cathodic migration, and the anion anode is moved.

Below in conjunction with accompanying drawing the inventive method is further described.

1., the electrode setting: on pending soil both sides electrode wells is set, installing electrodes in the electrode wells, the parallel symmetry of electrode is placed, electrode spacing is 0.1-1m, uses lead that anode and cathode is coupled together, and constitutes a complete galvanic cell, as shown in Figure 2; A plurality of electrode wells perhaps are set, anode and cathode alternately is installed, use lead that the negative electrode of a galvanic cell is continuous with the anode of adjacent galvanic cell, realize the series connection of a plurality of galvanic cells, as shown in Figure 3; Anode is selected reproducibility material preferably for use, and as iron, aluminium, carbon, negative electrode is selected oxidisability material preferably for use, as carbon, manganese dioxide, guarantees that different electrode reactions takes place anode and cathode.

2., flushing liquor setting: the acid solution (sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, ethylenediamine tetra-acetic acid, citric acid) of filling 0-2mol/L in the electrode wells, and by pump with being communicated with towards Xian's liquid storage tank, the liquid level that guarantees electrode wells is higher than processing soil height, and make soil have certain humidity, the cathode and anode material is immersed in the flushing liquor.

3., be communicated with processing: use lead to connect anode and cathode, processing soil is under the weak electric field effect of anode and cathode generation, the electrodynamics migration effect will take place in pollutant wherein, cation anode (negative electrode of galvanic cell) migration, anion is to negative electrode (anode of galvanic cell) migration, and interstitial water generation electrodialysis migration makes pollutant that corresponding migration take place.Be the intensive treatment process, in service can be on soil spray irrigation liquid.Different with concentration according to pollutant kind, generally continued conduction time between 30-500 days.

Embodiment 1: copper is a kind of typical heavy metal contaminants, and environment is had bigger harmfulness.Delivery is intended copper polluted soil 150g, and copper content is 170mg/kg, configuration moisture content 50%, and the galvanic cell reaction unit of packing into is (among the Φ 5cm * 8cm).Anode uses iron filings, and negative electrode uses activated carbon, and the anode chamber and the cathode chamber (100mL) is filled the dilute acid soln (0mol/L, the sulfuric acid of 0.1mol/L and 0.5mol/L) of variable concentrations, is communicated with anode and cathode with lead.Handle after 30 days, find that by analysis copper concentration is raise to carbon gradually by iron, as shown in Figure 4.X/L is a test point apart from ferroelectric pole span from divided by the reactor length overall.

Embodiment 2: cadmium is a kind of typical heavy metal contaminants, and environment is had great harmfulness.Get a certain amount of simulation cadmium pollution soil, cadmium content is 160mg/kg, configuration moisture content 50%, and the galvanic cell reaction unit of packing into (among the Φ 5cm * 20cm), is connected three galvanic cell devices simultaneously by the mode shown in Fig. 2 b.Anode uses iron filings, and negative electrode uses activated carbon, and the anode chamber and the cathode chamber (100mL) is filled the 0.2mol/L hydrochloric acid solution, is communicated with anode and cathode with lead.Handle after 30 days, find that by analysis cadmium concentration is raise to carbon gradually by iron in the single reaction post, the series connection of a plurality of galvanic cell reaction columns can the extension process zone, as shown in Figure 5.X/L is a test point apart from ferroelectric pole span from divided by the reactor length overall, the situation when first, second of C1, C2 and C3 representative series connection and the 3rd galvanic cell, C are represented single galvanic cell.

Claims (1)

1. the restorative procedure of a heavy-metal contaminated soil the steps include:

(1) on pending soil both sides electrode wells is set, the yin, yang electrode is installed in the electrode wells, the parallel placement of electrode, electrode spacing is 0.1-1m; When anode material adopted iron or aluminium, negative electrode adopted manganese dioxide, carbon or copper; When anode material adopted carbon, negative electrode adopted manganese dioxide;

(2) in above-mentioned electrode wells, fill flushing liquor, make the liquid level of electrode wells be higher than processing soil height, and the cathode and anode material is immersed in the flushing liquor; Flushing liquor is water or the concentration acid solution smaller or equal to 2mol/L, and acid is sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, ethylenediamine tetra-acetic acid or citric acid;

(3) use lead to connect cathode and anode, conduction time is between 30-500 days.

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