CN108339849B - Soil remediation agent and method for remediating organically-contaminated or mercury-contaminated soil - Google Patents
Soil remediation agent and method for remediating organically-contaminated or mercury-contaminated soil Download PDFInfo
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- CN108339849B CN108339849B CN201810125460.5A CN201810125460A CN108339849B CN 108339849 B CN108339849 B CN 108339849B CN 201810125460 A CN201810125460 A CN 201810125460A CN 108339849 B CN108339849 B CN 108339849B
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- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
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Abstract
The invention discloses a soil repairing agent and a method for repairing organic pollution or mercury pollution soil, wherein the soil repairing agent comprises a ferrous chloride solution with pH of 4-5 and mass concentration of 3-5%, and the method for repairing organic pollution or mercury pollution soil comprises the following steps: taking organic polluted or mercury polluted soil to be repaired; preparing a soil remediation agent; adding the soil remediation agent into the organic polluted or mercury polluted soil to be remediated, mixing and stirring to obtain a mixture; and placing the mixture in a microwave reactor for reaction to obtain the repaired soil. The invention aims to provide a soil remediation agent and a remediation method for efficiently remedying soil and remedying organic-polluted or mercury-polluted soil with high desorption rate.
Description
Technical Field
The invention relates to the technical field of soil remediation, in particular to a soil remediation agent and a method for remediating organic-polluted or mercury-polluted soil.
Background
The economic growth, industrialization and urbanization of the last thirty years bring great material wealth to China and improve the living standard of people. However, the energy consumption and the industrial and agricultural production activities also seriously damage the ecological environment of China, and the atmospheric pollution, the water pollution, the soil and the underground water pollution threaten the health of people at any moment and also restrict the further sustainable development of the Chinese economy.
Mercury pollution has high toxicity and durability, is easy to accumulate by plants into the food chain to cause acute or chronic poisoning of people, and has been widely concerned at home and abroad. In recent years, the control of mercury in China is strengthened, but mercury can be widely used in various fields such as thermometers, calomel batteries, fluorescent lamps and the like. Common inorganic mercury species in mercury-contaminated soilClass HgO, HgS, HgNO3、HgSO4And the like, the organic mercury species include mainly methyl mercury and dimethyl mercury. Methyl mercury has the greatest toxicity, high neurotoxicity, carcinogenicity, immune system toxicity and the like, and mercury pollution causes greater risk to human beings due to slow methylation in soil.
At present, gas phase extraction, chemical leaching, thermal desorption technology, biological method and the like are mainly adopted for the soil remediation technology aiming at heat-sensitive pollutants such as organic pollution, heavy metal mercury and the like, but the soil remediation technology is difficult to degrade by adopting the biological method for a pollution field with high toxicity and high pollution level. Many organic pollutants which are not easy to degrade are difficult to degrade organic matters in a short time due to the influence of the external environment, and the repair period is long; for physical means such as chemical leaching and vapor extraction, all organic pollutants are difficult to transfer to a liquid phase or a vapor phase, and secondary pollution can be caused by incomplete pollutant phase collection; the thermal desorption technology is applied to organic pollution sites or sites with heat-sensitive pollutants such as mercury and the like, but the related equipment of the thermal desorption technology is expensive, the energy consumption during desorption is high, and soil clay minerals can be irreversibly denatured due to the high temperature of desorption (500 plus 800 ℃), so that the physical and chemical properties of soil are influenced. The research and development of high-efficiency, low-energy-consumption and rapid remediation technology has made the thermal desorption of high-boiling-point organic pollutants at low temperature become an important subject in the field of soil remediation.
Aiming at an organic polluted soil field, the traditional chemical oxidation technology utilizes strong oxidants of ozone, hydrogen peroxide, potassium permanganate, a Fenton reagent, persulfate, percarbonate and the like, the lower the oxidation potential is, the more difficult the organic pollutants are to be degraded, the strongest oxidability of the Fenton reagent can be known according to the strength of the oxidation-reduction potential, but the Fenton reagent is extremely unstable, easy to decompose and uncontrollable and needs to be prepared and used on site in the using process, and the soil injection distribution is not uniform due to punching injection in site implementation, and the pollutant oxidative degradation effect is not good. Ozone is gas, and the effect is better to sandy soil after punching and injecting into the soil layer, but the poor viscidity soil effect of air permeability is not obvious.
In related documents, organic matters with low molecular weight and medium boiling point are decomposed by microwave synergistic with sodium percarbonate to pollute soil, the desorption rate is not high, the oxidation potential of percarbonate is not too high, the organic pollution is not obvious in oxidation, the removal rate is generally over 40%, the desorption effect on heat-sensitive heavy metal mercury is not strong, the mercury removal efficiency is not high (about 22.2%), and the application range is not wide.
The method adopts Fenton reagent to catalyze and oxidize reaction to repair the organic polluted soil, has a slightly obvious desorption effect on low-molecular organic acid, has good activity only under the condition that the pH value is close to 3, has a relatively single effect, cannot achieve the expected degradation effect on some organic matters, and has a TOC removal rate of not more than 60 percent; with the need for spent chemical H2O2The method has the advantages of large using amount, large using amount of iron powder, low catalytic efficiency and unobvious actual catalytic action, and the iron powder is difficult to be uniformly mixed when being added into soil, so that iron pollution is easy to cause, partial degradation can only occur, and the effect on heat-sensitive heavy metal pollution is poor.
Disclosure of Invention
The main object of the present invention is to propose a soil remediation agent and a method for remediating organically or mercury contaminated soil by using Fe2+The electron transfer of the dissolved oxygen on the water-mineral interface is generated on the clay mineral surface to generate hydroxyl free radicals, and then the polar organic pollutants and water molecules are quickly deflected to generate pyrolysis by cooperating with the dipole polarization mechanism of the microwave, so that the technical problem of how to effectively repair the organic polluted or mercury polluted soil is solved.
In order to achieve the above object, the present invention provides a soil remediation agent, comprising:
ferrous chloride solution with pH of 4-5 and mass concentration of 3-5%.
In order to achieve the above object, the present invention provides a method for remediating organically-polluted or mercury-polluted soil, comprising the steps of:
taking organic polluted or mercury polluted soil to be repaired;
formulating the soil remediation agent of claim 1;
adding the soil remediation agent into the organic polluted or mercury polluted soil to be remediated, mixing and stirring to obtain a mixture;
and placing the mixture in a microwave reactor for reaction, and obtaining the restored soil through microwave synergistic action.
Preferably, in the step of adding the soil remediation agent into the organic polluted or mercury-polluted soil to be remediated, the mass ratio of the soil remediation agent to the organic polluted or mercury-polluted soil to be remediated is 1 (1.5-1.8).
Preferably, the ferrous chloride solution in the soil remediation agent is prepared by mixing ferrous chloride and dilute hydrochloric acid mother liquor.
Preferably, in the step of placing the mixture into a microwave reactor for reaction, the reactor is a variable frequency microwave reactor, the temperature in the variable frequency microwave reactor is set to be 150-200 ℃, and the reaction time is set to be 22-28 min.
Preferably, the organic polluted soil or mercury polluted soil to be repaired is soil containing 2,4, 4-trichlorobiphenyl and mercury oxide;
after the step of placing the mixture in a microwave reactor for reaction to obtain the repaired soil, the method also comprises the following steps:
and (4) measuring the concentration of the 2,4, 4-trichlorobiphenyl and the total mercury concentration in the repaired soil.
Preferably, after the step of placing the mixture in a microwave reactor for reaction to obtain the repaired soil, the method further comprises the following steps:
and maintaining the repaired soil for 40-48 h to enable the water content of the soil to reach more than 35%.
Preferably, after the step of maintaining the repaired soil for 40 to 48 hours to make the water content of the soil reach more than 35%, the method for repairing the organic contaminated or mercury contaminated soil further comprises the following steps:
and adjusting the pH value of the repaired soil by adopting pure calcium oxide or quicklime.
Preferably, the step of adjusting the pH value of the restored soil by using pure calcium oxide or quicklime specifically includes:
dissolving pure calcium oxide or quicklime with particle size less than 50.0 μm in water to form a solution with aqueous suspension;
applying the solution with the aqueous suspension to the remediated soil.
Preferably, the soil remediation agent is added into the organic polluted or mercury polluted soil to be remediated, and the mixing and stirring are carried out, wherein the stirring in the step of obtaining the mixture is mechanical stirring, and the rotating speed of the stirring is 20r/min-30 r/min.
Aiming at the traditional Fenton reagent, the method adopts Fe2+Electron transfer is carried out on dissolved oxygen on the water-mineral interface on the surface of the clay mineral to generate hydroxyl free radicals, and then polar organic pollutants and water molecules are quickly deflected to generate pyrolysis in cooperation with the dipole polarization mechanism of microwaves, so that the problem of uneven addition caused by adding Fenton reagent by aid of external aid can be solved, the reaction activation energy of organic pollutants which are difficult to degrade and have high boiling point is reduced through the synergistic effect, and the organic pollutants are quickly degraded;
further, aiming at a heat-sensitive heavy metal mercury polluted site, a soil layer is rapidly and uniformly heated through a microwave dipole polarization mechanism, chlorine ions are added to rapidly react with mercury to escape from the soil layer at a high temperature, and hydrogen ions formed by hydrolysis of iron ions are added to decompose inorganic mercury in the soil, so that rapid and efficient soil desorption is realized;
further, the invention sets the temperature in the frequency conversion type microwave reactor at 150-2+The method is characterized in that dissolved oxygen is subjected to electron transfer on a water-mineral interface on the surface of clay mineral to generate hydroxyl free radicals, polar organic pollutants and water molecules are quickly deflected to generate pyrolysis by cooperating with a dipole polarization mechanism of microwave, the organic pollutants can be removed by more than 80% by using a repairing agent to repair soil, and the removal rate of mercury is more than 95%.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a method for remediating organically-contaminated or mercury-contaminated soil according to an embodiment of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a soil remediation agent, which comprises ferrous chloride solution with pH of 4-5 and mass concentration of 3-5%.
Preferably, the ferrous chloride solution in the soil remediation agent is prepared by mixing ferrous chloride and dilute hydrochloric acid mother liquor.
Aiming at the traditional Fenton reagent, the method adopts Fe2+The electron transfer of dissolved oxygen on the water-mineral interface is carried out on the clay mineral surface to generate hydroxyl free radicals, and then the polar organic pollutants and water molecules are quickly deflected to generate pyrolysis by cooperating with the dipole deflection mechanism of microwaves. The problem of uneven addition caused by adding Fenton reagent by external aid can be solved, the reaction activation energy of organic pollutants which are difficult to degrade and have high boiling points is reduced through synergistic effect, and the organic pollutants are rapidly degraded. Aiming at a heat-sensitive heavy metal mercury polluted site, a soil layer is rapidly and uniformly heated through a microwave dipole polarization mechanism, chlorine ions are added to rapidly react with mercury to escape from the soil layer at a high temperature, and hydrogen ions formed by hydrolysis of iron ions are added to decompose inorganic mercury in the soil, so that the mercury in the soil is rapidly and efficiently desorbed.
The present invention also provides a method for remediating organically-polluted or mercury-polluted soil, referring to fig. 1, the method for remediating organically-polluted or mercury-polluted soil comprising the steps of:
step S210, taking organic polluted or mercury polluted soil to be repaired;
preferably, the step S210 further includes:
and grinding and crushing the organic polluted or mercury polluted soil to be repaired, and screening by adopting a 40-mesh sieve.
Step S220, preparing a soil remediation agent;
wherein in the step 220, the soil remediation agent comprises a ferrous chloride solution with pH of 4-5 and mass concentration of 3-5%.
For example, the soil remediation agent can be a ferrous chloride solution with pH of 4 and mass concentration of 3%; the solution may be a ferrous chloride solution having a pH of 4.5 and a mass concentration of 3.5%, and is not particularly limited.
Preferably, the ferrous chloride solution in the soil remediation agent is prepared by mixing ferrous chloride and dilute hydrochloric acid mother liquor.
Step S230, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
wherein the mass ratio of the soil remediation agent to the organic polluted or mercury polluted soil to be remediated in the step S230 is 1 (1.5-1.8).
Preferably, the mass ratio of the soil remediation agent to the organic polluted or mercury polluted soil to be remediated can be 1:1.6, 1:1.65, 1:1.70 or 1: 1.75.
In the step S230, the stirring is mechanical stirring, and the stirring speed is 20r/min-30 r/min.
And S240, placing the mixture in a microwave reactor for reaction, and obtaining the repaired soil through the microwave synergistic effect.
Wherein, the reactor in the step S240 is a frequency conversion type microwave reactor, the temperature in the frequency conversion type microwave reactor is set to be 150-.
Specifically, when the temperature in the variable-frequency microwave reactor is set to be too low, part of organic pollutants cannot be decomposed, the time required for degrading the organic pollutants or thermally desorbing mercury-containing pollutants is long, and the removal rate is lower; when the temperature is too high, the change of soil properties and the reduction of organic matter content in soil can be caused, the significance of soil remediation is lost, the reduction range is maximum in the temperature range of 200-360 ℃, and compared with the non-heating state, the organic carbon loss rate is rapidly increased from 8.6% at 200 ℃ to 83.34% at 360 ℃. The invention is favorable for the decomposition and the destruction of organic pollutants by setting the temperature to be 150-200 ℃, and has faster volatilization of mercury-containing pollutants and good synergistic effect.
The microwave synergistic effect is that polar organic pollutants or mercury-containing polluted soil and water molecules are quickly deflected to generate pyrolysis by utilizing a dipole polarization mechanism of microwaves, the reaction time is too short, and the generated heat energy cannot completely decompose and destroy the organic pollutants; the reaction time is too long, the evaporation of water in the polluted soil is almost exhausted, and the anhydrous molecules generate pyrolysis through the dipole polarization effect rapid deflection of the microwave, so that the organic pollutants or the mercury-containing polluted soil can not be continuously pyrolyzed to remove the pollutants.
Preferably, the temperature setting may be 155 ℃, 165 ℃, 170 ℃, 175 ℃, 180 ℃, 185 ℃, 190 ℃ or 195 ℃. The reaction time may be set to 23min, 24min, 24.5min, 25min, 25.5min, 26min, 26.5min, 27min or 27.5 min.
Preferably, the organic polluted soil or mercury polluted soil to be repaired is soil containing 2,4, 4-trichlorobiphenyl and mercury oxide; after the step S240, the following steps are further included:
and step S250, measuring the concentration of the 2,4, 4-trichlorobiphenyl and the total mercury concentration in the repaired soil.
Preferably, after the step S240, the following steps are further included:
and S260, maintaining the repaired soil for 40-48 h to enable the water content of the soil to reach more than 35%.
Preferably, after the step S260, the following steps are further included:
and step S270, adjusting the pH value of the repaired soil by adopting pure calcium oxide or quicklime.
In operation, the step S270 specifically includes:
dissolving pure calcium oxide or quicklime with particle size less than 50.0 μm in water to form a solution with aqueous suspension;
applying the solution with the aqueous suspension to the remediated soil.
Preferably, said applying said solution with an aqueous suspension to said rehabilitated soil is in particular applying said aqueous suspension onto and/or into said soil in an amount of 50.0kg/ha to 100.0 kg/ha.
In the prior art, organic matters with low molecular weight and medium boiling point are decomposed by microwave synergistic with sodium percarbonate to pollute soil, the desorption rate is not high, the oxidation potential of percarbonate is not too high, the organic pollution is easy to decompose after the percarbonate is prepared into a solution, the advantage of oxidized organic pollution is not obvious, the desorption effect on heat-sensitive heavy metal mercury is not strong, and the application range is not wide. The method also adopts Fenton reagent to catalyze and oxidize reaction to repair the organically polluted soil, although the desorption effect of the low-molecular organic acid is slightly obvious, the effect is single, the using amount of the iron powder is large, the iron powder is difficult to uniformly mix when being added into the soil, the iron pollution is easy to cause, the local degradation can only occur, and the effect on the thermosensitive heavy metal pollution is poor.
In the method, ferrous chloride solution with pH of 4-5 and mass concentration of 3-5% is prepared and added into the organic polluted soil or mercury polluted soil to be repaired, and the mixture is mixed and stirred; the mass ratio of the ferrous chloride solution to the organic pollution or mercury pollution soil to be repaired is 1 (1.5-1.8), and Fe is utilized2+Electron transfer is carried out on dissolved oxygen on the water-mineral interface on the surface of the clay mineral to generate hydroxyl free radicals, and then polar organic pollutants and water molecules are quickly deflected to generate pyrolysis in cooperation with the dipole polarization mechanism of microwaves, so that the problem of nonuniform addition caused by adding Fenton reagent by aid of external assistance can be solved, the reaction activation energy of organic pollutants which are difficult to degrade and have high boiling point is reduced through the synergistic effect, and the organic pollutants are quickly degraded;
further, the invention sets the temperature in the frequency conversion type microwave reactor at 150-2+The method is characterized in that dissolved oxygen is subjected to electron transfer on a water-mineral interface on the surface of clay mineral to generate hydroxyl free radicals, polar organic pollutants and water molecules are quickly deflected to generate pyrolysis by cooperating with a dipole polarization mechanism of microwave, the organic pollutants can be removed by more than 80% by using a repairing agent to repair soil, and the mercury removal rate is more than 95%.
Soil remediation agent
The soil remediation agent comprises ferrous chloride solution with pH of 4-5 and mass concentration of 3-5%.
Example 1
In this example, the soil remediation agent is a ferrous chloride solution with a pH of 4.2 and a mass concentration of 3.2%.
Example 2
In this example, the soil remediation agent is a ferrous chloride solution with a pH of 4.3 and a mass concentration of 3.4%.
Example 3
In this example, the soil remediation agent is a ferrous chloride solution with a pH of 4.4 and a mass concentration of 3.6%.
Example 4
In this case, the soil remediation agent is a ferrous chloride solution with a pH of 4.5 and a mass concentration of 3.8%.
Example 5
In this example, the soil remediation agent is a ferrous chloride solution with a pH of 4.6 and a mass concentration of 4.2%.
Example 6
In this case, the soil remediation agent is a ferrous chloride solution with a pH of 4.7 and a mass concentration of 4.8%.
Method for remediating organically-or mercury-contaminated soil
(1) Taking organic polluted or mercury polluted soil to be repaired;
(2) preparing a soil remediation agent, wherein the soil remediation agent is a ferrous chloride solution with pH of 4-5 and mass concentration of 3-5%;
(3) adding the soil remediation agent into the organic polluted or mercury polluted soil to be remediated, mixing and stirring to obtain a mixture; preferably, the rotation speed of stirring is 20r/min-30 r/min.
(4) And placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 150-200 ℃, and the reaction time is set to be 22-28 min.
Effect verification of method for remediating organically-contaminated or mercury-contaminated soil
The effect of the method for restoring the organic contaminated or mercury-contaminated soil is verified, and in order to verify the effect, the organic contaminated or mercury-contaminated soil to be restored may be artificial organic contaminated or mercury-contaminated soil.
For example, 2,4, 4-trichlorobiphenyl and HgO are added into soil to obtain organic polluted or mercury polluted soil to be repaired; alternatively, the first and second electrodes may be,
adding 2, 4-dichlorophenol and HgO into soil to obtain organic polluted or mercury polluted soil to be repaired; alternatively, the first and second electrodes may be,
the organic polluted or mercury polluted soil to be repaired is obtained by adding gamma-hexachlorocyclohexane and HgO into the soil.
And verifying the concentration of 2,4, 4-trichlorobiphenyl or 2, 4-dichlorophenol or gamma-hexachloro-hexa contained in the repaired soil and the total mercury concentration of the soil.
Example 1
And adding 2,4, 4-trichlorobiphenyl and HgO into the soil to obtain the organic polluted or mercury polluted soil to be restored.
S1, taking the organic polluted or mercury polluted soil to be repaired; wherein the organic pollution or mercury pollution soil to be repaired contains 2,4, 4-trichlorobiphenyl with the concentration of 25mg/kg and HgO with the concentration of 300 mg/kg;
s2, adding 0.30g of ferrous chloride into 9.70g of dilute hydrochloric acid mother liquor, dissolving, uniformly mixing and stirring to prepare a ferrous chloride solution with the mass concentration of 3% to obtain the soil remediation agent, wherein the dilute hydrochloric acid mother liquor is prepared by hydrochloric acid and distilled water, and the pH value of the dilute hydrochloric acid mother liquor is 5;
s3, adding the soil remediation agent obtained in the step S2 into 15g of organic polluted or mercury polluted soil to be remedied, and uniformly mixing to obtain a mixture;
s4, placing the mixture into a variable frequency microwave reactor, setting the temperature to be 180 ℃, and continuing the reaction for 22min to obtain the repaired soil;
and S5, taking out the repaired soil and measuring the concentration of the 2,4, 4-trichlorobiphenyl in the soil and the total mercury concentration of the soil.
The concentration of the 2,4, 4-trichlorobiphenyl in the soil is reduced to 4.76mg/kg from 25mg/kg, the desorption rate of the 2,4, 4-trichlorobiphenyl reaches 80.96 percent, the total mercury concentration of the soil is reduced to 14.7mg/kg from 300mg/kg, and the desorption rate of mercury is 95.10 percent. This example also demonstrates that the method of the present invention for remediating organically or mercury contaminated soil works well.
Example 2
And adding 2, 4-dichlorophenol and HgO into the soil to obtain the organic polluted or mercury polluted soil to be repaired.
S1, taking the organic polluted or mercury polluted soil to be repaired; wherein the repaired organic polluted or mercury polluted soil contains 20mg/kg of 2, 4-dichlorophenol and HgO with the concentration of 300 mg/kg;
s2, adding 0.30g of ferrous chloride into 9.70g of dilute hydrochloric acid mother liquor, dissolving, uniformly mixing and stirring to prepare a ferrous chloride solution with the mass concentration of 3% to obtain the soil remediation agent, wherein the dilute hydrochloric acid mother liquor is prepared by hydrochloric acid and distilled water, and the pH value of the dilute hydrochloric acid mother liquor is 5;
s3, adding the soil remediation agent obtained in the step S2 into 15g of organic polluted or mercury polluted soil to be remedied, and uniformly mixing to obtain a mixture;
s4, placing the mixture into a variable frequency microwave reactor, setting the temperature to be 180 ℃, and keeping the reaction time for 22 min;
and S5, taking out the repaired soil and measuring the concentration of the 2, 4-dichlorophenol and the total mercury concentration in the soil.
The concentration of the 2, 4-dichlorophenol in the soil is reduced from 20mg/kg to 1.37mg/kg, the desorption rate of the 2, 4-dichlorophenol reaches 93.15 percent, the total mercury concentration of the soil is reduced from 300mg/kg to 10.0mg/kg, and the desorption rate of mercury is 96.67 percent. This example also demonstrates that the method of the present invention for remediating organically or mercury contaminated soil works well.
Example 3
The organic polluted or mercury polluted soil to be repaired is obtained by adding gamma-hexachlorocyclohexane and HgO into the soil.
S1, taking the organic polluted or mercury polluted soil to be repaired; wherein the repaired organic polluted or mercury polluted soil contains 20mg/kg of gamma-hexachlorocyclohexane and HgO with the concentration of 500 mg/kg;
s2, adding 0.30g of ferrous chloride into 9.70g of dilute hydrochloric acid mother liquor, dissolving, uniformly mixing and stirring to prepare a ferrous chloride solution with the mass concentration of 3% to obtain the soil remediation agent, wherein the dilute hydrochloric acid mother liquor is prepared by hydrochloric acid and distilled water, and the pH value of the dilute hydrochloric acid mother liquor is 5;
s3, adding the soil remediation agent obtained in the step S2 into 15g of organic polluted or mercury polluted soil to be remedied, and uniformly mixing to obtain a mixture;
s4, placing the mixture into a variable frequency microwave reactor, setting the temperature to be 180 ℃, and keeping the reaction time for 22 min;
and S5, taking out the repaired soil and measuring the concentration of the gamma-hexachlorocyclohexane and the total mercury concentration in the soil.
The concentration of the gamma-hexachloro cyclohexane in the soil is reduced to 2.59mg/kg from 20mg/kg, the desorption rate of the gamma-hexachloro cyclohexane reaches 87.05 percent, the total mercury concentration of the soil is reduced to 12.6mg/kg from 500mg/kg, and the desorption rate of the mercury is 97.48 percent. This example also demonstrates that the method of the present invention for remediating organically or mercury contaminated soil works well.
In order to make the soil remediation effect of the method for remediating organically-polluted or mercury-polluted soil provided by the invention more intuitive, the following description is made in combination with specific examples and comparative examples:
the invention provides a first group of treating agents (examples 1 to 4, comparative example 1 and comparative example 2), wherein the treating agents have the same weight, the treated soil is the same, the treating agents and the soil are added according to the mass ratio of 1:1.5, and the organic polluted soil or mercury polluted soil to be repaired contains 2,4, 4-trichlorobiphenyl with the concentration of 25mg/kg and HgO with the concentration of 300mg/kg to obtain the organic polluted soil or mercury polluted soil to be repaired.
Example 1
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is ferrous chloride solution with pH of 4.2 and mass concentration of 3.2%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 150 ℃, and the reaction time is set to be 22 min.
Example 2
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is ferrous chloride solution with pH of 4.3 and mass concentration of 3.4%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 160 ℃, and the reaction time is set to be 23 min.
Example 3
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is ferrous chloride solution with pH of 4.5 and mass concentration of 3.8%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 170 ℃, and the reaction time is set to be 25 min.
Example 4
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is a ferrous chloride solution with pH of 4.7 and mass concentration of 4.8%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 180 ℃, and the reaction time is set to be 28 min.
Comparative example 1
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is a ferrous chloride solution with pH of 5.2 and mass concentration of 6%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 140 ℃, and the reaction time is set to be 25 min.
Comparative example 2
And (4) not performing any treatment on 15g of the organic pollution or mercury pollution soil to be repaired.
The effects of the examples and comparative examples after soil remediation are shown in Table 1.
TABLE 1 Effect of each example and comparative example after soil remediation
As can be seen from table 1, after the soils are restored in examples 1 to 4, comparative example 1 and comparative example 2, the desorption rate of 2,4, 4-trichlorobiphenyl and the desorption rate of mercury in the soils restored in examples 1 to 4 are significantly higher than those in comparative example 1 and comparative example 2. The method for repairing the organic polluted soil or the mercury polluted soil provided by the invention has obvious repairing effect on the organic polluted soil or the mercury polluted soil.
In order to further embody the experimental effect of the microwave synergistic effect in the remediation agent, the invention is provided with a second group of treatment agents (examples 5 to 9, comparative examples 3 and comparative examples 4), the weight of each treatment agent is the same, the treated soil is the same, the treatment agents are added according to the mass ratio of 1:1.5, and the treatment agents are ferrous chloride solutions with the pH value of 4.5 and the mass concentration of 3.8%. The organic contaminated or mercury contaminated soil to be repaired is obtained by taking the example that the organic contaminated or mercury contaminated soil to be repaired contains 2,4, 4-trichlorobiphenyl with the concentration of 25mg/kg and HgO with the concentration of 300 mg/kg.
Example 5
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is ferrous chloride solution with pH of 4.5 and mass concentration of 3.8%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 150 ℃, and the reaction time is set to be 22 min.
Example 6
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is ferrous chloride solution with pH of 4.5 and mass concentration of 3.8%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 170 ℃, and the reaction time is set to be 22 min.
Example 7
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is ferrous chloride solution with pH of 4.5 and mass concentration of 3.8%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 190 ℃, and the reaction time is set to be 22 min.
Example 8
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is ferrous chloride solution with pH of 4.5 and mass concentration of 3.8%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 170 ℃, and the reaction time is set to be 25 min.
Example 9
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is ferrous chloride solution with pH of 4.5 and mass concentration of 3.8%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring to obtain a mixture;
and S4, placing the mixture in a variable frequency microwave reactor for reaction to obtain the repaired soil, wherein the temperature in the variable frequency microwave reactor is set to be 170 ℃, and the reaction time is set to be 28 min.
Comparative example 4
S1, taking 15g of organic pollution or mercury pollution soil to be repaired;
s2, preparing a soil repairing agent, wherein the soil repairing agent is a ferrous chloride solution with pH of 4.5 and mass concentration of 3.8%;
s3, adding the soil remediation agent into the organic polluted or mercury polluted soil to be remedied, mixing and stirring.
Comparative example 5
And (4) not performing any treatment on 15g of the organic pollution or mercury pollution soil to be repaired.
The effects after soil remediation of each example and comparative example are shown in Table 2.
TABLE 2 Effect of each example and comparative example after soil remediation
As can be seen from Table 2, after the soil is repaired by the soil repairing agent and the conditions of the invention in examples 5 to 9 and the microwave synergistic effect is added, the desorption rate of 2,4, 4-trichlorobiphenyl and the desorption rate of mercury are obviously higher than those of comparative example 3 and comparative example 4, and the soil repairing agent and the method for repairing the soil polluted by organic matters or mercury have obvious repairing effect on the soil polluted by organic matters or mercury.
Specifically, it can be seen from examples 5 to 9 that the method for repairing organic contaminated or mercury-contaminated soil provided by the present invention can remove organic contaminants by more than 80%, and the removal rate of mercury by more than 95%, and further verifies that the method for repairing organic contaminated or mercury-contaminated soil provided by the present invention has an obvious repairing effect on organic contaminated or mercury-contaminated soil.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (6)
1. A method for remediating organically-and mercury-contaminated soil comprising the steps of:
taking organic pollution and mercury pollution soil to be repaired, wherein the organic pollution and mercury pollution soil to be repaired is soil containing 2,4, 4-trichlorobiphenyl and mercury oxide;
preparing a soil remediation agent: adding ferrous chloride into the dilute hydrochloric acid mother liquor, dissolving, uniformly mixing and stirring to prepare a ferrous chloride solution with the mass concentration of 3-5% to obtain a soil remediation agent, wherein the pH value of the soil remediation agent is 4-5;
adding the soil remediation agent into the organic polluted soil and mercury polluted soil to be remediated, mixing and stirring to obtain a mixture;
placing the mixture in a microwave reactor for reaction, and obtaining the repaired soil through microwave synergistic effect, wherein the reactor is a variable frequency microwave reactor, the temperature in the variable frequency microwave reactor is set to be 150-;
and (4) measuring the concentration of the 2,4, 4-trichlorobiphenyl and the total mercury concentration in the repaired soil.
2. The method for remediating organically-and mercury-contaminated soil as recited in claim 1, wherein said step of adding said soil remediation agent to said organically-and mercury-contaminated soil to be remediated, the mass ratio of said soil remediation agent to said organically-and mercury-contaminated soil to be remediated being 1 (1.5-1.8).
3. The method for remediating organically-and mercury-contaminated soil as recited in claim 1, wherein the step of reacting the mixture in a microwave reactor to obtain remediated soil further comprises the steps of:
and maintaining the repaired soil for 40-48 h to enable the water content of the soil to reach more than 35%.
4. The method for remediating organically-polluted and mercury-polluted soil as claimed in claim 3, wherein after the step of maintaining the remediated soil for 40 hours to 48 hours to achieve a water content of the soil of 35% or more, the method for remediating organically-polluted and mercury-polluted soil further comprises the steps of:
and adjusting the pH value of the repaired soil by adopting pure calcium oxide or quicklime.
5. The method for remediating organically-polluted and mercury-polluted soil as claimed in claim 4, wherein the step of adjusting the pH of the remediated soil with pure calcium oxide or quicklime specifically comprises:
dissolving pure calcium oxide or quicklime with particle size less than 50.0 μm in water to form a solution with aqueous suspension;
applying the solution with the aqueous suspension to the remediated soil.
6. The method for remediating organically-and mercury-contaminated soil as recited in claim 1, wherein said step of adding said soil remediation agent to said organically-and mercury-contaminated soil to be remediated, mixing and agitating to obtain a mixed material is a mechanical agitation at a speed of 20r/min to 30 r/min.
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| CN112139236A (en) * | 2020-09-17 | 2020-12-29 | 南开大学 | Method for restoring pesticide-polluted soil by using microwave-enhanced Fenton oxidation technology |
| CN113429138B (en) * | 2021-07-16 | 2022-07-22 | 天津中材工程研究中心有限公司 | High-activity cement admixture for thermal desorption organic contaminated soil as well as preparation method and application of high-activity cement admixture |
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