CN103240268B - Two-dimensional inhomogeneous field experiment device for electrically repairing polluted soil - Google Patents

Abstract

The invention provides a two-dimensional non-uniform electric field experimental device for electrically repairing polluted soil, including a soil sample tank, a gas measuring device, a liquid circulation and measuring device, an electrode control system and a data acquisition system. The soil sample tank includes a tank body, a top cover, a bottom cover and bolts; the top cover and the bottom cover are provided with a central nut and a plurality of other ring nuts which are located around the nut and are symmetrical in the center, and electrodes are arranged between the upper and lower nuts; There are multiple probes evenly distributed on the cover; the gas measuring device is a graduated tube; the liquid circulation and measuring device includes a connecting pipe, a total shunt tube, a peristaltic pump and a liquid measuring device; the electrode control system is connected to the electrode; the data acquisition system is connected to the probe . The two-dimensional non-uniform electric field experimental device can well simulate the restoration of contaminated soil, facilitate real-time monitoring of various electrodynamic parameters during the experiment, and is conducive to the removal of pollutants, energy saving and high system stability. A device of value and application prospects.

Description

A two-dimensional non-uniform electric field experimental device for electrokinetic remediation of polluted soil

technical field

The invention relates to a device for purifying and treating pollutants, in particular to a two-dimensional non-uniform electric field experimental device for electrically repairing polluted soil, belonging to the fields of environmental protection and pollution prevention and control.

Background technique

With the continuation of my country's industrialization process and the large-dose, large-scale, and long-term use of pesticides in agricultural production, relatively serious soil pollution has accumulated, for example, in heavily polluted enterprises or industrial-intensive areas, industrial and mining areas and surrounding areas Areas with heavy soil pollution and high-risk areas have emerged in regional, urban and suburban areas. At the same time, the types of soil pollution are also showing a trend of diversification and complexity. For example, in many areas, new and old pollutants coexist, and inorganic-organic compound pollution is severe.

Soil pollution has obvious threats to the ecological environment, drinking water sources, agricultural product quality, and human health. In view of this, countries around the world have conducted a lot of in-depth research on the prevention, treatment, and harmless treatment of polluted soil, trying to find A quick, low-energy, cost-effective method for treating contaminated soil. Compared with developed countries in the West, my country has just started in soil treatment and remediation, and there is an urgent need for practical, simple and effective soil pollution remediation technologies and new devices.

At present, the remediation technologies of traditional contaminated soil mainly include advanced oxidation method, stabilization/solidification technology, chemical leaching method, high temperature pyrolysis method, phytoremediation method, microbial remediation method, gas phase extraction method, etc. However, these methods have many disadvantages. For example, the advanced oxidation method is likely to cause serious adverse effects on the physical and chemical properties of the soil; the stabilization/solidification technology only achieves the stabilization and solidification of heavy metals, and cannot fundamentally reduce the total amount of heavy metals in polluted soil; The chemical leaching method is only effective for specific soils and pollutants, with a small scope of application and low elution efficiency; the high-temperature pyrolysis method consumes a lot of energy and has adverse effects on the physical and chemical properties of the soil; although the phytoremediation method is relatively low in cost , the operation is simple, but the efficiency is too low and the time-consuming is too long; the cost of microbial remediation is high and the remediation period is long; the soil gas phase extraction method is suitable for the remediation of contaminated soil with high volatile organic compounds such as gasoline, benzene and tetrachlorethylene , and the removal efficiency is low and the cycle is long.

All of these have caused the application range and application value of the above method to be limited to a certain extent, and cannot be widely promoted. In recent years, the electrokinetic restoration method of polluted soil has been paid more and more attention. Scientists have conducted extensive and in-depth research on it, and developed a variety of electrokinetic restoration methods and corresponding devices.

CN1695834A discloses an electrokinetic restoration method for heavy metal polluted soil. The method uses an ion exchange membrane to separate the cathode from the soil sample to be tested, and uses porous ceramics to place between the ion exchange membrane and the soil to prevent the blockage of the ion exchange membrane, utilizes the H ⁺ and OH ^- generated by the electrode itself, and uses the ion The barrier function of the exchange membrane controls the pH value of the soil during the electrokinetic remediation process and accelerates the dissolution and migration of pollutants.

CN201454977U discloses a kind of electrodynamic adsorption composite restoration heavy metal contaminated soil device. The device includes an electrode made of graphite. The electrode includes an anode and a cathode. The anode is placed in the anode area, and the cathode is placed in the cathode area. From the anode area to the cathode area, separators for preventing the diffusion of heavy metal ions and porous adsorption for absorbing heavy metals are arranged in sequence. Material activated carbon, heavy metal-contaminated soil to be treated, porous adsorbent activated carbon for adsorbing heavy metals, and separators to prevent the diffusion of polluted heavy metal ions. In order to prevent the pH increase of the cathode area and the decrease of the pH of the anode area, the method of switching electrode polarity is adopted.

CN1899717B discloses a process for joint restoration of heavy metal-contaminated soil by electrodynamic force and iron permeable reaction grid. The process is to install graphite electrodes on both sides of the soil, place an iron wall between the two electrodes and the soil to be treated, turn on the power, and under the action of an electric field, the metal anions migrate to the vicinity of the anode, and the metal cations migrate to the vicinity of the cathode. When passing through the iron wall, it reacts with it to be adsorbed, reduced and precipitated.

CN202356398U discloses an electric restoration device for removing heavy metals and organic pollutants in soil. The device includes an electric repair column, an electrode, an electrolytic cell, an electrolyte treatment cell, an acidity meter and a DC power supply. The pH automatic control system ensures the comparability of the results, improves the control accuracy, and can improve the efficiency of the polluted soil. removal of pollutants.

CN102500610A discloses a method for repairing heavy metal-contaminated soil by electrokinetics combined with drip irrigation. The method is to install positive and negative electrodes at both ends of the polluted soil, place an adsorbent between the positive and negative electrodes and the polluted soil, set a drip irrigation device above the soil near the adsorbent, and pour electrolyte, buffer or complexing agent, etc. Add it dropwise to the soil on both sides, and periodically switch the electrodes, so that the heavy metals will be adsorbed by the adsorbent through electrokinetic migration, thereby reducing the concentration of heavy metals in the soil.

CN102806228A discloses a device and method for ex-situ electric restoration of polluted soil. The device includes a soil bearing system, an electrode system and an electrode working fluid spraying system. During operation, the charges of the upper electrode and the lower electrode of the electrode system are opposite.

CN102896143A discloses an experimental device for combined restoration of polluted soil with electrokinetic surfactants. The device includes a main body containing polluted soil and non-polluted soil, and two parallel electrode chamber porous baffles are vertically installed on the two sides of the main body corresponding to the polluted soil, and the two porous baffles form two sides with the inner surface of the main body. Each of the electrode chambers is equipped with electrodes, and the treatment effect of polluted soil can be improved by applying current to the electrodes.

CN202667240U discloses a remediation device for oil-contaminated soil based on high-voltage static electricity. The device includes a high-voltage power supply, a high-voltage electrostatic soil treatment part, a high-voltage electrostatic dust collection part, and an insulating part. The high-voltage electrostatic soil treatment part includes electrodes, and the petroleum hydrocarbons in the polluted soil can be discharged by applying pressure between the electrodes to form a discharge. Classes are decomposed, and the toxic substances generated by the decomposition are adsorbed by the high-voltage electrostatic dust collection part. The device is mainly used for remediation of polluted soil caused by oil production and transportation industries.

As mentioned above, although people have developed a variety of electrodynamic restoration devices and methods, they all have some disadvantages, for example: 1. Plate-shaped materials are often used as electrodes. 2. The positive and negative electrodes are distributed on both sides of the polluted soil, causing the pollutants to move in a straight line, and it is likely to enter the closed space of the soil and cannot migrate to the electrode end. 3. Unable to measure important parameters such as electrodialysis flow and gas generation rate during the experiment. 4. Only a uniform and stable uniform electric field can be formed, and the positive and negative electrodes cannot be switched freely or the switching is cumbersome, resulting in high energy consumption and unstable system operation.

For these reasons, in the field of contaminated soil treatment, there is still a strong demand for new, effective, and highly effective contaminated soil remediation methods and devices, which is also a research focus and hotspot in the field of soil remediation.

Contents of the invention

In view of the defects and deficiencies of the above-mentioned technologies, the inventors proceeded from practical applications and conducted a lot of in-depth research on the device for electric restoration of polluted soil. After paying creative work, they developed a device for electric restoration of polluted soil. During the experiment, additives or synergists can be continuously added to the soil, such as complexing agents, chelating agents, surfactants, acid-base salt solutions, buffer solutions, microorganisms, etc. to promote the desorption and degradation of pollutants in the soil Or various chemical reaction processes, and the electrode control system controls the arranged electrodes at the same time, thus generating a non-uniform electric field, which can cause non-linear two-dimensional migration of pollutants in the soil such as heavy metals, and through the use of peristaltic pumps. Neutralize the pH of each electrode, reduce energy consumption, and at the same time facilitate the measurement of important parameters such as electrodialysis flow, gas, and voltage during the experiment, and help analyze the mechanism of electrodynamic repair. superior to all current similar devices.

In order to achieve the above object, the present invention provides a two-dimensional non-uniform electric field experimental device for electrically repairing polluted soil. Specifically, the device includes a soil sample tank, a gas measuring device, a liquid circulation and measuring device, an electrode control system and data collection system.

Wherein, the soil sample tank includes a tank body, a top cover, a bottom cover, and bolts for fixing the tank body, top cover, and bottom cover; a plurality of nuts are arranged on the corresponding positions of the top cover and the bottom cover, One of the nuts is located at the center, and the rest of the nuts are located around the center nut, and are distributed in a ring with the center nut as the center of symmetry; electrodes are arranged between the corresponding upper and lower nuts, that is, the central electrode and a plurality of A ring electrode; a plurality of probes protruding into the soil sample tank are evenly distributed on the top cover.

The gas measuring device is a graduated tube connected to the upper end of each electrode.

The liquid circulation and measurement device includes a connecting pipe connected to the lower end of the central electrode, a total shunt pipe formed by merging the shunt pipes connected to the lower end of the ring electrode, a peristaltic pump connected to the connecting pipe and the main shunt pipe, respectively A liquid measuring device connected to the end of the connecting pipe and the end of the main distribution pipe.

The electrode control system is connected to each electrode.

The data acquisition system is connected to each probe.

Among them, in the process of using the device for electric repair, any of the following (1)-(4) power-on methods are used for electric repair:

(1). With the central electrode as the center of the circle, connect the central electrode clockwise or counterclockwise to the ring electrodes symmetrically distributed on both sides in the same straight line, and change the polarity of the electrodes regularly on each connection. Before switching to the next connection, change the polarity of the electrode several times until a complete power-on is completed, and so on to complete the soil electric repair;

(2). With the central electrode as the center of the circle, connect the central electrode clockwise or counterclockwise to the ring electrodes symmetrically distributed on both sides in the same straight line. In each connection, the electrode polarity does not change from beginning to end. After energizing for a certain period of time, switch to the next connection sequence. After completing a complete energization, change the polarity of the electrode for the next complete energization, and repeat this to complete the soil electrodynamic restoration;

(3). Power on with "A+mB" as the cycle unit:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized at the same time;

B: Take the central electrode as the center of the circle, connect and energize the central electrode and the symmetrically distributed ring electrodes on both sides in the same straight line clockwise or counterclockwise, and change the polarity of the electrodes regularly on each connection , change the electrode polarity several times before switching to the next connection until a complete power-on is completed;

Where m is an integer, and 1≤m≤4;

(4). Power on with "A+nC" as the cycle unit:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized at the same time;

C: With the central electrode as the center of the circle, connect the central electrode and the ring electrodes symmetrically distributed on both sides in the same straight line in a clockwise or counterclockwise direction. In each connection, the polarity of the electrodes is not changed from beginning to end, and the electricity is applied. After a certain period of time, switch to the next connection sequence until a complete power-on is completed;

Wherein n is an integer, and 2≤n≤4, and when switching to the next complete energization of C after completing one C energization, change the electrode polarity.

In this application, unless otherwise specified, the meaning of "completely energized" means that when the energized connection returns to the position of the initial central electrode and the symmetrically distributed ring electrodes on both sides in the same straight line, that is, complete a circular loop.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, the three-dimensional shape of the soil sample tank is not particularly limited, for example, it may be cylindrical, cuboid, square, etc. Its volume is not particularly limited, and can be properly selected according to the amount of soil treatment and actual operation conditions. Its material is not particularly limited, as long as it has a certain strength, insulation and can withstand the pressure during operation, non-limiting examples can be polyester materials, tempered glass, PVC and so on.

In the two-dimensional non-uniform electric field experimental device for electrodynamic restoration of polluted soil of the present invention, the top cover and the bottom cover are respectively located at the upper and lower parts of the tank body, and can completely cover the tank body, so as to be compatible with the tank body The body constitutes a closed volume space to contain the contaminated soil to be treated. The materials of the top cover and the bottom cover are not particularly limited, as long as they have certain strength, insulation and can bear the pressure during operation, non-limiting examples can be polyester materials, tempered glass, PVC and the like.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, the tank body, top cover and bottom cover are fixed together by bolts, that is, in the tank body, top cover and bottom cover At the overlap, the bolts pass through the top cover, the tank body and the bottom cover sequentially from top to bottom; or the top cover and the bottom cover are larger than the horizontal cross-sectional area of the tank body, that is, the edges of the top cover and the bottom cover protrude from the tank body In addition, the bolts pass through the protruding edge parts of the top cover and the bottom cover from top to bottom, thereby "clamping" the tank body tightly to realize the fixing of the three. Through the above fixing, a closed space for containing the polluted soil to be treated can be formed. Preferably, for better sealing, sealing rings are provided between the top cover and the tank body, and between the bottom cover and the tank body. In a non-limiting manner, the material of the sealing ring can be any known sealing material, such as various sealing rubbers, non-limiting examples include nitrile rubber, fluororubber, silicon rubber or acrylic rubber.

In the two-dimensional non-uniform electric field experimental device for electrically repairing polluted soil of the present invention, the top cover and the bottom cover are provided with a plurality of nuts at corresponding positions, and one of the nuts is located between the top cover and the bottom cover. center position, and the other nuts are located around the center nut and distributed in a ring with the center nut as the center of symmetry. Electrodes are arranged between the corresponding upper and lower nuts of the top cover and the bottom cover, that is, the upper and lower center positions are the central electrodes, and multiple electrodes at the rest of the nut positions form ring-shaped electrodes.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, the number of the annular electrodes is not particularly limited, and can be properly selected and selected according to the area of the horizontal section of the tank body. /or determined, so as to present a symmetrical arrangement with the center position of the central electrode, for example, in terms of the distance to the central electrode, the ring-shaped electrode can only surround the central electrode in one circle, or surround the central electrode in multiple circles, for example, 2 -4 circles; the "circle" here does not specifically refer to the form of circles, but also includes forms arranged equidistantly from the edge of the soil sample tank.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, as a preferred embodiment, the electrodes (unless otherwise specified, when used as "the electrodes" and "each electrode" , means that the central electrode and the ring electrode, the same below) are both hollow. More preferably, the hollow electrode is provided with small holes on the electrode tube wall for liquid inflow and outflow, for example, these small holes can be evenly distributed, and the aperture can be 0.5mm-5mm, for example, it can be 0.5mm, 1mm , 2mm, 3mm, 4mm or 5mm.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil in the present invention, as a preferred embodiment, an anti-leakage device is provided on the periphery of the electrode to prevent soil particles from entering the hollow electrode and affecting the electrode. normal operation and loss. The anti-leakage device is not particularly limited, as long as it can prevent soil particles from entering the electrode, such as filter paper, filter cloth or filter screen.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil in the present invention, a plurality of probes extending into the soil sample tank are uniformly distributed on the top cover, in short, Evenly distributed small holes are opened on the top cover to insert the probes, and then the probes can be tightened to fix them. The length of the probe is not particularly limited, as long as it can penetrate into the soil without touching the bottom cover, for example, it can be 1/3-2/3 of the electrode length. The purpose of setting the probe is to measure the two-dimensional voltage distribution of the soil to be treated, thereby completing data collection, determining parameters such as the applied voltage gradient, and providing the most direct data display for smooth operation and result determination. The type of the probe is not particularly limited, as long as it can measure the voltage generated in the soil, it can be any known voltage probe.

In the two-dimensional non-uniform electric field experimental device for electrically repairing polluted soil of the present invention, the gas measuring device is a scale tube connected to the upper end of each electrode, and the upper part of the scale tube is provided with an opening that can be opened or closed. , the volume of the gas can be determined by the drop of the liquid level. When the gas volume is not measured, it is in the open state, and the pressure at the liquid surface is kept at ambient pressure.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, the liquid circulation and measurement device includes a connecting pipe connected to the lower end of the central electrode, and a shunt pipe connected to the lower end of the ring electrode. The main shunt pipe of the main shunt pipe, the peristaltic pump connected with the connecting pipe and the main shunt pipe, and the liquid measuring device connected with the end of the connecting pipe and the shunt pipe end.

Wherein, one end of the connecting pipe is connected to the lower end of the central electrode, and the other end is connected to the liquid measuring device. The shunt pipe is connected to the lower ends of all the ring electrodes and merged into a main shunt pipe. The peristaltic pump is connected to the connecting pipe and the main distribution pipe. The peristaltic pump is not particularly limited as long as it can circulate and return the liquid in the liquid measuring device. Any known peristaltic pump can be used. By using a peristaltic pump and selecting its peristaltic direction according to needs, the liquid from the anode or cathode can be returned to the cathode or anode, respectively, so that the pH value can be neutralized, avoiding damage caused by too high or too low pH value Precipitation of pollutants under acidic/alkaline conditions.

Wherein, the ends of the connecting pipe and the total shunt pipe are connected to a three-way pipe, and the three-way pipe flows the liquid from the electrode into the liquid measuring device through one of the passages, while the other passage is connected to the atmosphere. connected.

Among them, part of the liquid flowing out from the electrode can be returned to the electrode through the peristaltic pump to achieve neutralization of the pH value, and the remaining part can be discharged into the liquid measuring device to achieve the purpose of removing pollutants and repairing the soil. The amount of reflow to the electrode can be appropriately selected according to the degree of neutralization.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, the electrode control system is connected with each electrode. Through the electrode control system, the polarity of the central electrode and all ring electrodes can be controlled and switched, so as to apply a non-uniform electric field to the soil, realize the control of the movement process and mode of pollutants, and facilitate the study of the migration and removal mechanism of pollutants , resulting in good measurement and contaminant removal.

Wherein, when using the device for soil remediation, the above-mentioned energization method (1) can be used for electric repair, preferably, the method (1) is as follows:

(1). With the central electrode as the center of the circle, connect the central electrode clockwise or counterclockwise to the ring electrodes symmetrically distributed on both sides of the same straight line. The energization time of each connection is t hours. Each connection is counted from the time of energization, and the polarity of the electrode is changed after t1 hour of energization, and the energization is continued for t2 hours until the set time t, and then switched to the next energized connection until a complete energization is completed, and so on to complete the soil electric restoration. .

Wherein, in this method, the above-mentioned energization method (2) can be used for electric restoration, preferably, the energization method (2) is as follows:

and After the energization time reaches t3 hours, switch to the next energization connection until a complete energization is completed, and then change the electrode polarity for the next complete energization with each energization connection time of t4 hours, and repeat this for each energization connection. Complete energization of t3 and t4 until completion of soil electroremediation.

Wherein, in this method, the above-mentioned energization method (3) can be used for electric restoration, preferably, the energization method (3) is as follows:

(3). Power on with "A+mB" as the cycle unit:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized at the same time;

B: With the central electrode as the center of the circle, connect the central electrode and the ring electrodes symmetrically distributed on both sides in the same straight line in a clockwise or counterclockwise direction. The energization time of each connection is t hours. When the connection is started, the time is counted when the power is turned on, and the electrode polarity is changed after the power is turned on for t1 hours, and the power is continued for t2 hours until the set time t, and then switched to the next power-on connection until a complete power-on is completed;

Wherein m is an integer, and 1≤m≤4; for example, m can be 1, 2, 3 or 4.

Wherein, in this method, the above-mentioned energization method (4) can be used for electric restoration, preferably, the energization method (4) is as follows:

(4). Power on with "A+nC" as the cycle unit:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized at the same time;

C: With the central electrode as the center of the circle, connect the central electrode and the ring electrodes symmetrically distributed on both sides in the same straight line in a clockwise or counterclockwise direction, and do not change the polarity of the electrodes on each connection, and the electrification time After reaching t3 hours, switch to the next energized connection until a complete energization is completed, and then change the polarity of the electrodes to perform the next complete energization for each energized connection with a time of t4 hours, and repeat this for each energized connection. The upper energized time is t3 and t4 complete electrification until completion of soil electric restoration;

Wherein n is an integer, and 2≤n≤4, and when switching to the next complete energization of C after completing one C energization, change the electrode polarity; for example, n can be 2, 3 or 4.

For the above mode (1) or mode B: the "t" is 2-8 hours, such as 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours; "t1" is 1 -7.5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours or 7 hours; "t2" is 0.5-4 hours, such as 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours hours, 3 hours, 3.5 hours or 4 hours, provided that t1+t2=t.

For the above mode (2) or mode C: the "t3" is 1-4 hours, such as 1 hour, 2 hours, 3 hours or 4 hours, during which the electrode polarity is not changed. After the energization time reaches the set value t3 hours, switch to the next connection sequence and continue energizing for t3 hours until a complete energization is completed, that is, during the complete energization period, the polarity of the central electrode and the ring electrodes on both sides remains unchanged. The electrodes are switched until a complete energization cycle is completed, and the next complete energization is started. In this "next complete energization", the energization time on each energization connection is t4 hours, and the "t4" is 0.5 -1 hour, for example, it can be 0.5 hours or 1 hour. After completing a complete power-on, perform a complete power-on for each power connection for t3 hours, and then perform a complete power-on for each power connection for t4, and repeat for t3+ The cycle of t4 is repeated until the soil treatment is completed.

For the above method (3): the "A+mB" method refers to using "A+mB" as the cycle unit to energize, and its meaning is to first carry out simultaneous energization for a certain period of time such as 4-12 hours in the method A, and then use the method A B is energized, and after a complete power-on is completed, the method B is energized again until the method B is energized for m times, and then the method A is energized again, and then the method B is energized again for m times... so on and on until it is completed Electrokinetic pollution treatment of soil.

For the above method (4): the "A+nC" method refers to using "A+nC" as a cycle unit to energize, and its meaning is to first conduct simultaneous energization with method A for a certain period of time, such as 4-12 hours, and then use method A C is energized, and a complete energization is completed (that is, when the energized connection returns to the position of the initial central electrode and the ring electrodes symmetrically distributed on both sides in the same straight line, that is, a circular cycle is completed), and then proceed again. Mode C is energized until n times of power-on in mode C, then power-on in mode A again, and then power-on in mode B again for n times... This cycle goes on and on until the electrokinetic pollution treatment of the soil is completed, and each time in mode C After completing a full power cycle, reverse the polarity of the center and ring electrodes.

More specifically, in short, the above mode (1) is the cycle of mode B, and the above mode (2) is the cycle of mode C.

Taking Figure 4 as an example, for the above-mentioned (1), (2), B or C power-on methods, the anti-clockwise "1-2-3-4" power-on connection sequence shown in the figure can be used. First, the connection sequence "1" is energized, and then switched to the connection sequence "2", that is, the central electrode and the two ring electrodes that are 45o and 225o based on the horizontal axis are energized, and then the connection sequence "3" and "4" Apply power to complete a full cycle, and then enter the next "1-2-3-4" power-up cycle; of course, a clockwise "1-4-3-2" power-up sequence can also be used. The power-on sequence and timing switching include the above-mentioned two ways (1) or (2).

Take method A as an example: the central electrode is used as the cathode, and all the annular electrodes are used as the anode, and the anode and the cathode are simultaneously energized for 4-12 hours.

Take method B as an example: for example, when the order of energization connection is "1", that is, energize the central electrode and the two ring electrodes on the horizontal plane. On the energization connection, the total energization time is t hours, and t is 2-8 Hours, such as 6 hours, from the start of energization, when energized for t1 hours, such as 4 hours, change the electrode polarity [that is, exchange the polarity of the central electrode and the ring electrode], continue to energize for t2 hours, such as 2 hours, to reach the total value of t1 The power-on time is like 6 hours; then switch the power-on sequence to the next sequence "2", continue to switch the power-on time and timing in the same way, and so on, power on according to the "1-2-3-4" power-on connection sequence . When cyclic energization is carried out in this mode B all the time, it is the energization mode of preferred mode (1).

Take method C as an example: the energization time is 1-4 hours, for example, when the energization connection sequence is "1", that is, the central electrode and the two ring electrodes on the horizontal plane are energized, and the energization time is t3 hours such as 2 hours without changing the electrode polarity. After the energization time reaches the set value, switch to the sequence "2", that is, energize the central electrode and the two ring electrodes whose baselines are 45° and 225° with the horizontal axis as the baseline, and continue to energize for t3 hours, such as 2 hours. By analogy, power on according to the "1-2-3-4" power-on connection sequence to complete a complete cycle. Electrode switching is then performed, and the next full energization of "1-2-3-4" is performed, in which the energization time on each energized connection is t4 hours, such as 0.5 or 1 hour, to complete a full After energization, complete energization for each energized connection for t3 hours is performed again, and then complete energized for each energized connection for t4, and the repeated cycle of t3+t4 is repeated until the soil treatment is completed. When cyclic energization is carried out in mode C, it is the energization mode of preferred mode (2).

The timing switching of the anode and the cathode can be realized between the central electrode and the ring electrode through the electrode control system, and the timing switching includes a variety of ways (specifically described in the "Description of the Drawings" below). By switching, the sharp rise or fall of the pH value of the soil near the electrode can be advantageously controlled, which stabilizes the performance of the system. Wherein, for the smooth operation of the electrode control system, it is connected to a DC power source to obtain power sources with different voltage gradients.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, as a preferred embodiment, an ammeter is arranged between the electrode control system and the central electrode to display the applied current data, It is typically 1mA-1000mA, for example may be 1mA, 5mA, 10mA, 50mA, 100mA, 200mA, 300mA, 400mA, 500mA, 600mA, 700mA, 800mA, 900mA or 1000mA. .

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, the data acquisition system is connected with each probe. Through the data acquisition system, the two-dimensional voltage data measured by all probes can be collected, so as to provide direct data for the operator to select and/or change the voltage. Generally speaking, the applied voltage should be such that the The voltage gradient is 0.1V/cm-5V/cm, such as 0.1V/cm, 0.5V/cm, 1V/cm, 2V/cm, 3V/cm, 4V/cm or 5V/cm.

In the two-dimensional non-uniform electric field experimental device for electrokinetic restoration of polluted soil of the present invention, additives or synergists can be continuously added to the soil during the experiment, such as complexing agents, chelating agents, surfactants, acid-base Salt solution, buffer solution, microorganisms, etc. to promote the desorption, degradation or various chemical reaction processes of pollutants such as heavy metals and organic pollutants in soil. This addition can be done through the three-way port at the end of the connecting pipe and the total distribution pipe, and can be added at any time according to the removal of pollutants.

This addition can be done manually, for example, the required additives or synergists can be manually added, but as a preferred embodiment, the two-dimensional non-uniform electric field experimental device also includes a liquid adding device, which can realize Addition of required additives or synergists can be done, for example, in graduated containers such as pipettes, burettes and the like.

The beneficial effects of the present invention are:

1. Use the central electrode and the ring electrode to apply a non-uniform electric field to the soil, so that the pollutants can migrate in a non-linear two-dimensional manner, preventing them from entering the closed pores, and can better simulate the actual repair situation. Through the probe By measuring the two-dimensional voltage distribution in the soil, the voltage gradient distribution can be easily determined.

2. Use a peristaltic pump to return the liquid from the electrode, which can neutralize the acidity/alkalinity of the electrode, prevent the precipitation of pollutants at high or low pH values, and be more conducive to the removal of pollutants.

3. Different electrode polarities can be switched through the electrode control system, and due to the innovative change of electrode layout, the contact and reaction between pollutants and soil solution is strengthened, and the acidity and alkalinity near the electrode are neutralized, thereby saving energy consumption , to maintain system stability.

As described above, the present invention provides a novel electrokinetic remediation device capable of removing pollutants in soil such as heavy metals or organic pollutants. The device has many excellent features and is very suitable for remediation treatment of polluted soil.

Description of drawings

In order to illustrate the device of the present invention more clearly, the accompanying drawings that need to be used in the description of the embodiments will be briefly introduced below, but obviously, the accompanying drawings described below are only some embodiments of the present invention. Ordinary technicians can also obtain similar improved drawings based on these drawings without paying creative work.

Fig. 1 is a schematic structural view of the device of the present invention.

Fig. 2 is the top view of the cylindrical soil sample tank of the device of the present invention.

Fig. 3 is a schematic diagram of soil sample preparation by the device of the present invention.

Fig. 4 is a schematic diagram of the control sequence of the electrodes located in the cylindrical soil sample tank of the device of the present invention.

Wherein, the corresponding relationship between each digital number and/or code and the elements/parts of the device of the present invention is as follows:

Detailed ways

The device and method of the present invention will be further described and/or illustrated with reference to the accompanying drawings, but it should be understood that this is only an exemplary description of the device and its operating method of the present invention, and its intention is to explain / To illustrate the device and its implementation of the present invention, but not to limit and/or limit the present invention, and not to limit the protection scope of the present invention thereto.

Referring to FIG. 1 , the device of the present invention includes a soil sample tank, a gas measurement device 11 , a liquid circulation and measurement device, an electrode control system 13 and a data acquisition system 12 . Wherein, the soil sample tank includes a tank body 1, a top cover 2, a bottom cover 3, and bolts 8 for fixing the tank body 1, a top cover 2, and a bottom cover 3. In order to enhance the sealing performance, the top cover 2 and the tank A sealing ring 7 is provided between the bodies 1 and between the bottom cover 3 and the tank body 1 .

The corresponding positions of the top cover 2 and the bottom cover 3 are provided with a plurality of nuts (not shown), one of which is located at the center, and the rest of the nuts are located around the center nut, with the center nut as the center of symmetry in a circular distribution. Electrodes are arranged between the corresponding upper and lower nuts, namely the central electrode 4 and a plurality of annular electrodes 5. The electrodes are hollow, and the electrode tube wall is provided with a plurality of small holes evenly distributed. A leak-proof device (not shown), such as filter paper, filter cloth or filter screen, is provided around. A plurality of probes 6 protruding into the soil sample tank are evenly distributed on the top cover 2 .

The gas measuring device 11 is a graduated tube connected to the upper end of the electrode.

The liquid circulation and measurement device includes a connecting pipe 17 connected to the lower end of the central electrode 5, a shunt pipe 16 connected to the lower end of the ring electrode 5, a peristaltic pump 10 located between the connecting pipes, the end of the connecting pipe 17 and the shunt pipe The liquid measuring device that the end of 16 is connected.

The electrode control system 13 is connected with each electrode, and is powered by a DC power supply 14 for operation. An ammeter is arranged between the electrode control system 13 and the central electrode 4, so that the magnitude of the current in the soil can be detected.

The data acquisition system 12 is connected with each probe 6, so that the voltage distribution gradient in the soil can be detected in real time.

The device of the present invention can also include a liquid adding device 20, which can add additives, synergists or microorganisms, etc. And into the soil, the efficient removal of pollutants is achieved under the action of a non-uniform electric field.

With reference to Fig. 2, this figure is the top view of the soil sample tank of the device of the present invention. The horizontal section of the tank body is circular, on which is a top cover, and is fixed by a plurality of bolts 8 . The central position is the central electrode 4, and a plurality of annular electrodes 5 are symmetrically distributed around the central position, and a plurality of evenly distributed probes 6 are inserted on the top cover. In order to enhance the sealing performance, a sealing ring 7 is arranged between the top cover and the tank body.

Referring to Fig. 3, this figure is a schematic diagram of soil sample preparation by the device of the present invention. When preparing a soil sample of polluted soil, the soil sample tank is turned upside down, and the top cover 2 is used as a bottom plate during soil sample preparation, and the nuts of all electrodes are unscrewed, and the probe 6 is unscrewed. Place a shrinkage tank 19 with the same inner diameter as the tank body above the tank body 1, and place a shrinkage plate 18 with a slightly smaller inner diameter than the shrinkage tank 19 above the shrinkage tank 19, such as smaller than the inner diameter of the shrinkage tank 19. 1-5mm, so that it can tightly enter the inside of the shrinkage tank 19 and compact the poured polluted mud. The shrinkage plate 18 has a plurality of small holes to discharge the water overflowing during compaction. .

When the soil sample is prepared, the mud is slowly poured into the tank 1, mixed evenly, and then a filter screen or filter cloth is laid on the mud, and then the solidification plate 17 is placed, and an external force is applied to press the solidification plate 17 downward, Thus, the mud is consolidated and compressed. During the compression process, the water in the mud can flow out from the pores of the electrodes, the gaps at the probe holes and the small holes on the solidification plate 18 .

When the compression ends, after finishing the consolidation, take away the solidification tank 19 and the solidification plate 18, and remove the placed filter screen or filter cloth, and properly remove excess soil according to the volume of the soil sample tank (when not redundant , it does not need to be removed). Then put on the bottom cover 3, tighten the bolt 8 and the probe 6, and tighten the nut of the electrode. Then the soil sample tank is turned over to complete the soil sample preparation.

Referring to FIG. 4 , this figure is a schematic diagram of the electrode control sequence of the device of the present invention. This figure exemplarily shows an electrode control sequence such as the above-mentioned mode (1) or (2) or B or C. Through the control of the electrode control system, the timing power on and off of the central electrode and the ring electrode can be realized. electricity, and a switch in polarity. For example, the counterclockwise "1-2-3-4" power connection sequence shown in the figure can be used, and the clockwise "1-4-3-2" power connection sequence can also be used. Through the electrical connection sequence and the electrode polarity control method, a non-uniform electric field can be applied to the polluted soil, which is very beneficial to the removal of pollutants and can save energy consumption.

The present invention will be further described below in conjunction with specific examples, but it should be understood that these examples are used for illustration purposes only, and are not used to limit and intend to limit the scope of application and implementation of the present invention, and are not intended to protect the present invention. The scope is limited to this.

Embodiment 1: For the removal test of heavy metal Cd

With reference to the soil sample preparation method of Fig. 3, prepared the test soil sample that Cd content is 300mg/kg, and described soil sample groove size is 14cm (long) * 14cm (wide) * 5cm (high), wherein is the cross section The center of the inscribed circle of the square is the central electrode, and a circle of ring-shaped electrodes is regularly arranged on the periphery. These ring-shaped electrodes are evenly arranged with the central electrode as the symmetrical center, and the distance from the edge of the soil sample tank is 1cm.

The electrode is hollow, and small holes with a diameter of 3 mm are provided on the electrode tube wall. A filter cloth is arranged around the electrode to prevent soil from entering the hollow electrode. Nitrile rubber sealing rings are arranged between the top cover and the tank body and between the bottom cover and the tank body of the soil sample tank to maintain good sealing performance. In order to measure the voltage at different positions to determine the voltage gradient, the A plurality of probes are inserted on the top cover of the soil sample tank, and its length is 2/3.

Cycle power "A+B" as follows:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized for 4 hours at the same time;

B: With the central electrode as the center of the circle, connect and energize the central electrode and the symmetrically distributed ring electrodes on both sides in a counterclockwise direction. Each connection is energized for 2 hours, and every 1 hour during the energization period Change electrode polarity once, that is, change electrode polarity 2 times before switching to the next connection, until a full pass is completed.

After completing an "A+B", proceed to the next "A+B" again...until the entire soil electrification treatment is completed.

The electrical repair treatment has a total of 510 hours of electrical treatment, of which the energizing voltage for 0-160 hours is 24V, the energizing voltage for 160-190 hours is 20V, the energizing voltage for 190-204 hours is 15V, and the energizing voltage for 204-260 hours is 12V , 260-510 hours of power-on voltage is 24V. Although these power-on times have coincident endpoint values, they do not affect the smooth implementation and normal understanding of the technical solution. For example, taking 160 hours as an example, the power-on voltage is 24V during the period from the start of power-on to exactly 160 hours, and reaches 160 hours. Hours, immediately change the voltage to 20V. The remaining coincident endpoint values have the same meaning.

During the electrification process, through the liquid adding device, add the mixed aqueous solution of citric acid and acetic acid to the ring electrode at the three-way port at the end of the total shunt pipe, wherein the concentration of citric acid is 3g/L and the concentration of acetic acid is 5.5g/L, Add a mixed aqueous solution of citric acid and acetic acid to the central electrode through the tee port at the end of the connecting tube, wherein the concentration of citric acid is 3g/L and the concentration of acetic acid is 6.1g/L, and the pH of these two mixed aqueous solutions is 2.0. During normal operation, the pH value of the anode and cathode is neutralized by a peristaltic pump to keep it between 3-5, so that no heavy metal precipitation occurs near the anode or cathode, and at the same time, the remaining electrodes are passed out of the liquid into the liquid The measuring device is discharged to achieve the purpose of removing Cd ions and repairing the soil.

After the operation was completed, the average Cd ion content in the soil sample was measured, and it was found that its concentration was reduced from 300mg/kg at the beginning to 10mg/kg, and the removal rate was 96.67%.

Embodiment 2: For the removal test of heavy metal Cd

Example 2 was carried out in the same manner as in Example 1 except for energizing in the following manner.

Cycle power "A+2B" as follows:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized for 12 hours at the same time;

B: With the central electrode as the center of the circle, connect and energize the central electrode and the symmetrically distributed ring electrodes on both sides of the same line in a counterclockwise direction. Each connection is energized for 1.5 hours, and every 0.5 hours during the energization period Change electrode polarity once, i.e. change electrode polarity 3 times until a full pass is complete before switching to the next connection.

After the operation was completed, the average Cd ion content in the soil sample was measured, and it was found that its concentration was reduced from 300mg/kg at the beginning to 12.5mg/kg, and the removal rate was 95.83%.

Embodiment 3: For the removal test of heavy metal Cd

Example 3 was carried out in the same manner as in Example 1 except for energizing in the following manner.

Power cycle "A+4B" as follows:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized for 12 hours at the same time;

B: With the central electrode as the center of the circle, connect and energize the central electrode and the symmetrically distributed ring electrodes on both sides in a counterclockwise direction. Each connection is energized for 1 hour, and every 0.5 hours during the energization period Change electrode polarity once, that is, change electrode polarity 2 times before switching to the next connection, until a full pass is completed.

After the operation was completed, the average Cd ion content in the soil sample was measured, and it was found that its concentration was reduced from 300mg/kg at the beginning to 13mg/kg, and the removal rate was 95.67%.

Embodiment 4: For the removal test of heavy metal Cd

The operation of this embodiment was carried out in the same manner as that of Embodiment 1 except that the following power-on method was followed.

Power cycle "A+2C" as follows:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized for 4 hours at the same time;

C: With the central electrode as the center of the circle, connect the central electrode and the ring electrodes symmetrically distributed on both sides in the same straight line in a clockwise or counterclockwise direction. In each connection, the polarity of the electrodes is not changed from beginning to end, and the electricity is applied. After 1 hour, switch to the next connection sequence until a complete power-on is completed.

After the operation was completed, the average Cd ion content in the soil sample was measured, and it was found that its concentration was reduced from 300mg/kg at the beginning to 20.1mg/kg, and the removal rate was 93.33%.

Embodiment 5: For the removal test of heavy metal Cd

The operation of this embodiment was carried out in the same manner as that of Embodiment 1 except that the following power-on method was followed.

Power cycle "A+3C" as follows:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized for 8 hours at the same time;

C: With the central electrode as the center of the circle, connect the central electrode and the ring electrodes symmetrically distributed on both sides in the same straight line in a clockwise or counterclockwise direction. In each connection, the polarity of the electrodes is not changed from beginning to end, and the electricity is applied. After 3 hours, switch to the next connection sequence until a complete power-on is completed.

After the operation was completed, the average Cd ion content in the soil sample was measured, and it was found that its concentration decreased from 300mg/kg at the beginning to 22.9mg/kg, and the removal rate was 92.37%.

Embodiment 6: For the removal test of heavy metal Cd

The operation of this embodiment was carried out in the same manner as that of Embodiment 1 except that the following power-on method was followed.

Power cycle "A+4C" as follows:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized for 12 hours at the same time;

C: With the central electrode as the center of the circle, connect the central electrode and the ring electrodes symmetrically distributed on both sides in the same straight line in a clockwise or counterclockwise direction. In each connection, the polarity of the electrodes is not changed from beginning to end, and the electricity is applied. After 4 hours, switch to the next connection sequence until a complete power-on is completed.

After the operation was completed, the average Cd ion content in the soil sample was measured, and it was found that its concentration decreased from 300mg/kg at the beginning to 21.4mg/kg, and the removal rate was 92.87%.

Embodiment 7-9: For the removal test of heavy metal Cd

Embodiments 7-9 were implemented in the same manner as in Embodiment 1, except that the following energization methods were used.

Cycle power in the following way (1):

The energization method (1) of embodiment 7: with the central electrode as the center of the circle, the central electrode and the ring electrodes symmetrically distributed on both sides of the same straight line are sequentially connected and energized in the counterclockwise direction, and energized on each connection For 2 hours, during the power-on period, the central electrode is used as the cathode and the ring electrode is used as the anode for 1.5 hours, and then the polarity of the electrodes is changed for 0.5 hours, that is, the central electrode is used as the cathode and the ring electrode is used as the anode. Switch to the next connection and carry out energization in the same way for 2 hours until a complete energization is completed, and the cycle is repeated until the soil treatment is completed.

The energization method (1) of embodiment 8: with the central electrode as the center of the circle, the central electrode and the ring-shaped electrodes symmetrically distributed on both sides of the same straight line are sequentially connected and energized in the counterclockwise direction, and energized on each connection For 4 hours, during the power-on period, the central electrode is used as the cathode and the ring electrode is used as the anode for 3 hours, and then the polarity of the electrodes is changed for 1 hour, that is, the central electrode is used as the anode and the ring electrode is used as the cathode. Switch to the next connection and carry out energization in the same way for 4 hours until a complete energization is completed, and the cycle is repeated until the soil treatment is completed.

The energization method (1) of Embodiment 9: with the central electrode as the center of the circle, the central electrode and the symmetrically distributed annular electrodes on both sides of the same straight line are sequentially connected and energized in a counterclockwise direction, and energized on each connection 8 hours, during the power-on period, the central electrode is used as the cathode, and the ring electrode is used as the anode for 6 hours, and then the electrode polarity is changed for 2 hours, that is, the central electrode is used as the anode, and the ring electrode is used as the cathode. Switch to the next connection and carry out energization in the same way for 8 hours until a complete energization is completed, and the cycle is repeated until the soil treatment is completed.

After the operation was completed, the average Cd ion content in the soil samples of Examples 7-9 was measured respectively, and it was found that the Cd removal rate was 90.1%-91.4%.

Embodiment 10-12: For the removal test of heavy metal Cd

Embodiments 10-12 were implemented in the same manner as in Embodiment 1, except that the following energization methods were used.

Cycle power in the following way (2):

The energization method (2) of Embodiment 10: take the central electrode as the center of the circle, connect the central electrode clockwise or counterclockwise to the ring electrodes symmetrically distributed on both sides in the same straight line with it. First use the central electrode as the cathode and the ring electrode as the anode to energize each connection for 1 hour without changing the polarity of the electrodes. After 1 hour, switch to the next connection sequence. After completing a complete energization, change the polarity of the electrodes. The next full energization cycle, ie with the central electrode as the anode and the ring electrodes as the cathode, was energized on each connection for 0.5 hours. This cycle goes on and on until the total power-on time reaches 510 hours, and the final soil electro-remediation treatment is completed.

The electrification mode (2) of embodiment 11: take the central electrode as the center of the circle, and connect the central electrode clockwise or counterclockwise to the ring electrodes symmetrically distributed on both sides in the same straight line. First use the central electrode as the cathode and the ring electrode as the anode to energize each connection for 2.5 hours without changing the polarity of the electrodes. After 2.5 hours, switch to the next connection sequence. After completing a complete energization, change the polarity of the electrodes. The next full energization cycle, ie with the central electrode as the anode and the ring electrodes as the cathode, was energized on each connection for 0.5 hours. This cycle goes on and on until the total power-on time reaches 510 hours, and the final soil electro-remediation treatment is completed.

The energization method (2) of Embodiment 12: take the central electrode as the center of the circle, and connect the central electrode clockwise or counterclockwise to the ring electrodes symmetrically distributed on both sides in the same straight line. First use the central electrode as the cathode and the ring electrode as the anode to energize each connection for 4 hours without changing the polarity of the electrodes. After 4 hours, switch to the next connection sequence. After completing a complete energization, change the polarity of the electrodes. The next full energization cycle, ie with the central electrode as the anode and the ring electrodes as the cathode, was energized on each connection for 1 hour. This cycle goes on and on until the total power-on time reaches 510 hours, and the final soil electro-remediation treatment is completed.

After the operation was completed, the average Cd ion content in the soil samples of Examples 10-12 was measured respectively, and it was found that the Cd removal rate was 90.1%-91.2%.

Embodiment 13: For the removal test of heavy metal Zn

Except that the heavy metal was replaced by Zn ions, the test was carried out in the same manner as in Example 1.

After the operation is completed, the average Zn ion content in the soil sample is measured, and it is found that its concentration is reduced from 300mg/kg at the beginning to 12mg/kg, and the removal rate is 96.00%.

Embodiment 14: Degradation and removal test for petroleum

Referring to the soil sample preparation method in FIG. 3 , using the same device as in Example 1, a test soil sample with a petroleum content of 50 g/kg was prepared.

Cycle power in the following "A+2B" way:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized for 4 hours at the same time;

B: With the central electrode as the center of the circle, connect and energize the central electrode and the symmetrically distributed ring electrodes on both sides in a counterclockwise direction. Each connection is energized for 2 hours, and every 0.5 hours during the energization period Change electrode polarity once, i.e. change electrode polarity 4 times until a full pass is complete before switching to the next connection.

After completing an "A+B", proceed to the next "A+B" again...until the entire soil electrification treatment is completed. Among them, the power-on voltage is 24V, and the total power-on time is 900 hours.

During the power-on process, add oil-degrading bacteria and any known nutrient solution to the ring electrode through the main shunt tube and the three-way port at the end of the connecting tube, for example, the nutrient solution can be NH ₄ NO ₃ and KH ₂ PO ₄ Mix the aqueous solution, the concentration of both is 0.1mol/L, the pH of the mixture is 7.0, when the peristaltic pump is used to neutralize the pH value of the anode and cathode, so that it is controlled between 6-7.

After the operation is completed, the average oil content in the soil sample is measured, and it is found that its concentration is reduced from 50g/kg at the beginning to 17g/kg, and the removal rate is 66.70%.

Embodiment 15: Degradation and removal test for petroleum

The operation of this example was carried out in the same manner as that of Example 14, except that the power-on method was as follows.

Power cycle "A+2C" as follows:

A: With the central electrode as the cathode and the ring electrode as the anode, the anode and the cathode are energized for 4 hours at the same time;

C: With the central electrode as the center of the circle, connect the central electrode and the ring electrodes symmetrically distributed on both sides in the same straight line in a clockwise or counterclockwise direction. In each connection, the polarity of the electrodes is not changed from beginning to end, and the electricity is applied. After 1 hour, switch to the next connection sequence until a complete power-on is completed.

When the operation is finished, the average oil content in the soil sample is measured, and it is found that its concentration is reduced from 50g/kg at the beginning to 14g/kg, and the removal rate is 72.00%.

Embodiment 16: Degradation and removal test for petroleum

The operation of this example was carried out in the same manner as that of Example 14, except that the power-on method was as follows.

Carry out electricity according to method (1): take the central electrode as the center of the circle, connect and energize the central electrode and the symmetrically distributed ring electrodes on both sides in the same straight line in a counterclockwise direction, and energize each connection for 2 hours , change the electrode polarity every 0.5 hours during the energization period, that is, change the electrode polarity 4 times before switching to the next connection, until a complete energization is completed. This cycle goes on and on until the total power-on time reaches 900 hours, and the final soil electro-remediation treatment is completed.

When the operation is finished, the average oil content in the soil sample is measured, and it is found that its concentration is reduced from 50g/kg at the beginning to 15g/kg, and the removal rate is 70.00%.

Embodiment 17: Degradation and removal test for petroleum

The operation of this example was carried out in the same manner as that of Example 14, except that the power-on method was as follows.

Conduct electricity according to method (2): take the central electrode as the center of the circle, connect the central electrode clockwise or counterclockwise to the ring electrodes symmetrically distributed on both sides in the same straight line, and electrify each connection for 2 hours , do not change the electrode polarity from beginning to end, switch to the next connection sequence after 2 hours, after completing a complete power-on, change the electrode polarity for the next complete power-on cycle, and so on, until the total power-on time of 900 hours is completed The ultimate soil electro-remediation treatment.

After the operation is finished, the average oil content in the soil sample is measured, and it is found that its concentration is reduced from 50g/kg at the beginning to 9.15g/kg, and the removal rate is 81.7%.

Comparative example 1: Removal test for heavy metal Cd

With reference to the soil sample preparation method of Fig. 3, prepared the test soil sample that Cd content is 282mg/kg, and described soil sample tank size is 14cm (long) * 14cm (wide) * 5cm (high), in the square of cross section Three electrodes identical to the electrodes of the present invention are arranged on opposite sides, and the corresponding electrodes on both sides are 12 cm apart, that is, each electrode is 1 cm away from the edge of the soil sample tank.

The electrode is hollow, and small holes with a diameter of 3 mm are provided on the electrode tube wall. A filter cloth is arranged around the electrode to prevent soil from entering the hollow electrode. Nitrile rubber sealing rings are arranged between the top cover and the tank body and between the bottom cover and the tank body of the soil sample tank to maintain good sealing performance. In order to measure the voltage at different positions to determine the voltage gradient, the A plurality of probes are inserted on the top cover of the soil sample tank, the length of which is 2/3 of the electrode.

The electrodes on both sides are energized for a total of 510 hours, of which the energization voltage for 0-160 hours is 24V, the energization voltage for 160-190 hours is 20V, the energization voltage for 190-204 hours is 15V, and the energization voltage for 204-260 hours The voltage is 12V, and the power-on voltage for 260-510 hours is 24V.

In the process of electrification, add the mixed aqueous solution of citric acid and acetic acid to the side electrode at the three-way port at the end of the total shunt pipe connected to one side electrode through the liquid adding device, wherein the concentration of citric acid is 3g/L and the concentration of acetic acid is 5.5g/L. Add a mixed aqueous solution of citric acid and acetic acid to the other electrode at the three-way port at the end of the connecting pipe connecting the other electrode, wherein the concentration of citric acid is 3g/L and the concentration of acetic acid is 6.1g/L, and the two mixed aqueous solutions The pH is 2.0. During normal operation, neutralize the pH value of the anode and cathode through the peristaltic pump connected to the main shunt pipe and the connecting pipe, and keep it between 3-5, so as not to produce heavy metal precipitation near the anode or cathode. At the same time, through The remaining electrode effluent liquid is discharged into the liquid measuring device to achieve the purpose of removing Cd ions and repairing the soil. After the operation was completed, the average Cd ion content in the soil sample was measured, and it was found that its concentration decreased from 282mg/kg at the beginning to 43.15mg/kg, and the removal rate was 84.7%.

Comparative Example 2: Removal test for heavy metal Cd

With the central electrode as the cathode and the ring electrode as the anode, the heavy metal Cd removal test was carried out in the same manner as in Example 1, except that the method B was not energized.

After the operation was completed, the average Cd ion content in the soil sample was measured, and it was found that its concentration decreased from 300mg/kg at the beginning to 38.93mg/kg, and the removal rate was 87.02%.

Comparative Example 3: Degradation and removal test for petroleum

In addition to replacing the central electrode and multiple ring electrodes with two electrode plates arranged in parallel, manually adjusting the pH value of the anode and cathode to control it between 6-7, and every 2 hours for the two electrode plates Except for changing the polarity of the electrode once, the operation was carried out in the same manner as in Example 14, and the degradation and removal effect of the device on oil was tested.

When the operation is finished, the average oil content in the soil sample is measured, and it is found that its concentration is reduced from 50g/kg at the beginning to 20.48g/kg, and the removal rate is only 59.04%.

Comparative Example 4: Degradation and removal test for petroleum

Except that the polarity of the central electrode and the ring electrode is not changed from beginning to end (that is, the central electrode is always the anode, the ring electrode is always the cathode, or the central electrode is always the cathode, and the ring electrode is always the anode), in accordance with Example 14 Operate in the same way to test the degradation and removal effect of oil.

After the operation is finished, the average oil content in the soil sample is measured, and it is found that its concentration is reduced from 50g/kg at the beginning to 24.26g/kg, and the removal rate is only 51.48%.

From above-mentioned all examples and comparative examples, it can be clearly seen that when the device and soil remediation method of the present invention are used, it has a good removal rate for heavy metals and organic pollutants. In terms of effect, "A+mB">"A+nC">"(1) or (2)", and when removing organic pollutants, "(2)" has the highest removal rate, and "A+mB" has the lowest .

But no matter for heavy metals or organic pollutants, the method of the present invention is significantly better than the removal rate of any prior art, which proves that the device of the present invention has more excellent pollutant removal than similar devices in the prior art However, when using the same device of the present invention, the pollutant removal effect has been further and unexpectedly improved and improved, which further proves the excellent effect and good application prospect of the device of the present invention for electric remediation of polluted soil.

Although for the purpose of illustration and description, the above-mentioned embodiments of the present invention and the structures and processes shown in the drawings are introduced. However, these are not intended to be exhaustive and are not intended to limit the scope of the invention thereto. For those skilled in the art, various modifications and changes can be made to the above-mentioned embodiments of the present invention, and all these modifications and/or changes are included within the scope defined by the claims of the present invention and do not depart from The scope and spirit of the invention is defined by the appended claims.

Claims (10)

1. for a two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution, it is characterized in that: described device comprises soil sample groove, gas measurement device, liquid-circulating and measurement mechanism, electrode control system and data collecting system;

Described soil sample groove comprises cell body, top cover, bottom, and for fixing the bolt of cell body, top cover, bottom; The opposite position of described top cover and bottom is provided with multiple nuts, and one of them nut is positioned at center, and all the other nuts are positioned at this center nut around, and distributes ringwise take described center nut as symmetrical centre; Between corresponding upper lower nut, be provided with electrode; On described top cover, be also evenly distributed with the multiple probes that extend into described soil sample groove inside;

Described gas measurement device is the graded tube being connected with each electrode upper end;

Described liquid-circulating and measurement mechanism comprise the tube connector that is connected with contre electrode lower end, converge the total isocon forming, the peristaltic pump being connected with total isocon with described tube connector, the device for measuring volumetric flow of fluid that is connected with total isocon end with tube connector end respectively by the isocon being connected with ring electrode lower end;

Described electrode control system is connected with each electrode;

Described data collecting system is connected with each probe.

2. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as claimed in claim 1, is characterized in that: the form that described electrode is hollow.

3. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as claimed in claim 2, is characterized in that: for the described electrode of hollow form is provided with aperture on electrode tube wall.

4. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as claimed in claim 1, is characterized in that: described electrode periphery is provided with leak-proof device.

5. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as claimed in claim 4, is characterized in that: described leak-proof device is filter paper, filter cloth or filter screen.

6. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as claimed in claim 1, is characterized in that: between described top cover and cell body, be equipped with sealing ring between bottom and cell body.

7. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as claimed in claim 6, is characterized in that: described sealing ring is acrylonitrile-butadiene rubber, fluorubber, silicon rubber or ACM.

8. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as claimed in claim 1, is characterized in that: the 1/3-2/3 that the length of described probe is electrode length.

9. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as claimed in claim 1, is characterized in that: described device also comprises liquid adding apparatus.

10. the two-dimentional inhomogeneous field experimental provision for Electroremediation soil pollution as described in claim 1-9 any one, is characterized in that: between described electrode control system and contre electrode, be provided with ammeter.

Images