CN113070332B - Compound eluting agent for repairing polycyclic aromatic hydrocarbon contaminated soil and application thereof - Google Patents
Compound eluting agent for repairing polycyclic aromatic hydrocarbon contaminated soil and application thereof Download PDFInfo
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Abstract
The invention relates to a compound eluent for repairing polycyclic aromatic hydrocarbon contaminated soil and application thereof, wherein the compound eluent comprises solute and solvent, the solute comprises citric acid and alkyl glycoside, the concentration of the citric acid in the compound eluent is (0.2/3-0.4/3) g/L, and the concentration of the alkyl glycoside in the compound eluent is (10/3-20/3) g/L. The application specifically comprises the following steps: (1) weighing a soil sample containing polycyclic aromatic hydrocarbon after pretreatment, adding a compound eluent and uniformly mixing to obtain a repair sample; (2) placing the uniformly mixed repairing sample obtained in the step (1) in a constant-temperature oscillation box for uniform oscillation reaction to ensure that the soil is fully contacted with the compound eluting agent; (3) in the oscillating reaction process, a part of the repair sample is taken out at each set time point, filtrate and filter residue are respectively obtained after filtration, and then the concentration of the polycyclic aromatic hydrocarbon in the filtrate is measured. Compared with the prior art, the invention realizes the purposes of high-efficiency and durable treatment of pollutants and reduction of the remediation cost of the polluted soil.
Description
Technical Field
The invention belongs to the field of polluted soil remediation, and particularly relates to a compound eluent for remediation of polycyclic aromatic hydrocarbon-polluted soil and application thereof.
Background
In recent years, with the rapid development of industrialization and the continuous enlargement of urbanization scale in China, various chemical raw materials are widely applied to social production and life. The pollution problem of soil and groundwater environment is becoming more serious due to the overuse of chemical raw materials, the random discharge of waste, the unreasonable disposal of toxic and harmful substances, etc. Among them, Persistent Organic Pollutants (POPs) have become one of the important problems faced by current soil and groundwater remediation due to their characteristics of being difficult to degrade and causing harm to the environment for a long time. Polycyclic Aromatic Hydrocarbons (PAHs) are common POPs, which are formed by two or more benzene rings through sharing carbon atoms (such as naphthalene, anthracene, phenanthrene, benzo [ a ] pyrene, etc.), and mainly come from the processes of exploitation, production and use of chemical raw materials, including thermal cracking and incomplete combustion of fossil fuels, etc. Most PAHs are colorless or light yellow crystalline solids, have small vapor pressure and high melting point and boiling point, are easily dissolved in organic solvents and are easily adsorbed to organic matters and particles. PAHs are widely present in underground water and soil environments because of their characteristics of relatively stable nature, relatively low volatility, difficulty in degradation, certain water solubility and easiness in adsorption to soil. PAHs have strong "triotropism" (teratogenicity, carcinogenicity and mutagenicity). As early as 1982, the United states environmental protection agency lists 16 polycyclic aromatic hydrocarbons such as naphthalene, anthracene, phenanthrene, fluorene, benzo [ a ] pyrene and the like in a priority control pollutant list, mainly because the PAHs have higher toxicity, wider sources and more chances of contacting with human bodies. In recent years, pollution control and treatment of polycyclic aromatic hydrocarbons in groundwater and soil have gradually received attention from researchers at home and abroad.
The soil leaching technology is a polluted soil remediation technology which is efficient, simple, strong in operability, low in cost and free of secondary risk, and becomes one of hot spots and development directions for rapid remediation research of site polycyclic aromatic hydrocarbon polluted soil. In a broad sense, the soil washing technology is a method of removing pollutants in soil by using a fluid to wash out the pollutants in the soil, and performing a chemical reaction between the washing agent and the pollutants in the soil to perform mutual ion exchange, adsorption, precipitation, chelation and the like. Soil leaching can be divided into in-situ leaching and ex-situ leaching. The in-situ soil leaching technology is characterized in that an injection well is used for injecting a leaching agent into soil in a polluted site, and the leaching agent is made to permeate downwards to react with pollutants by the self gravity or external force of the leaching agent according to the distribution depth of the pollutants. In the process, the solvent containing the pollutants can be recovered by an extraction well and is discharged after reaching the standard after being treated. Ectopic soil leaching remediation techniques typically require five steps: (1) excavating the polluted soil; (2) transporting the excavated polluted soil to a specified polluted soil treatment plant; (3) mixing the polluted soil and the leacheate according to a certain solid-liquid ratio in a treatment plant, then putting the mixture into a leaching reactor or a reaction tank, and enabling the polluted soil and the leacheate to have a chemical reaction effect under the auxiliary action of external force such as stirring and the like; (4) after a certain time, after the pollutants in the soil are transferred from the solid phase to the liquid phase, the liquid can be separated by gravity infiltration; (5) the treated soil is transported back to the original site for backfilling or other uses, and the leacheate containing the pollutants needs to be treated and discharged or recycled after reaching the standard. Because the ectopic leaching technology is to transport the polluted soil to a distant ectopic leaching factory for leaching, the remediation time is long, the transportation cost is high, and the engineering quantity is large for a large polluted site, so that the realization is not easy. Therefore, the in-situ leaching technology is one of the soil remediation technologies which are widely applied at present.
The eluting agent is divided into an organic eluting agent, an inorganic eluting agent, a chelating agent and a surfactant. Common surfactants include Tween-80 (Tween-80), Triton X-100(TX-100), polyoxyethylene lauryl ether (Brij-35), Sodium Dodecyl Sulfate (SDS) and the like, and although the surfactants can effectively desorb pollutants from soil, the surfactants with higher concentration also exist in the soil and are easy to cause secondary pollution because the surfactants are difficult to biodegrade. Low molecular weight organic acids, such as citric acid, oxalic acid, malic acid and the like, are one of the most active components in plant root exudates, and are widely applied to soil heavy metal remediation due to the strong chelating ability, but the high-concentration organic acids can also increase the acidity of the soil and influence the physicochemical properties of the soil. In a word, although the existing eluting agent has a certain removal efficiency on polycyclic aromatic hydrocarbons, the existing eluting agent has a great influence on the physicochemical properties of soil, new pollutants can be brought after the eluting agent is eluted, and how to overcome the problems, the development of the eluting agent which is environment-friendly and low in price for treating the polycyclic aromatic hydrocarbons-polluted soil becomes the focus of research in the field.
Patent CN109135756A discloses an eluent for heavy metal contaminated soil and an elution recovery method thereof, wherein the eluent is a mixed aqueous solution of organic acid and biosurfactant alkyl glycoside, and the concentration of the organic acid in the mixed aqueous solution is as follows: 0.05-0.1mol/L, and the concentration of the alkyl glycoside is as follows: 0.2 to 8 percent. The compound eluent is used for restoring soil polluted by heavy metals, the heavy metals belong to inorganic pollutants, the compound eluent is used for restoring soil polluted by polycyclic aromatic hydrocarbons, the polycyclic aromatic hydrocarbons are organic pollutants, and the properties of the compound eluent are fundamentally different. Moreover, the concentration of organic acid in the washing agent is very high, which can cause soil acidification, so the washing agent disclosed in the patent needs to be subjected to pH adjustment during the use process.
Disclosure of Invention
The invention aims to provide a compound eluent for repairing polycyclic aromatic hydrocarbon contaminated soil and application thereof, thereby realizing the purposes of high-efficiency and durable treatment of pollutants and reducing the cost of repairing the contaminated soil.
The purpose of the invention is realized by the following technical scheme:
the compound eluent for repairing polycyclic aromatic hydrocarbon-polluted soil comprises a solute and a solvent, wherein the solute is citric acid and alkyl glycoside, the concentration of the citric acid in the compound eluent is (0.2/3-0.4/3) g/L, and the concentration of the alkyl glycoside in the compound eluent is (10/3-20/3) g/L. The compound eluent has low citric acid concentration and low acidity, and cannot cause soil acidification.
The solvent is ultrapure water.
When the concentration of the citric acid in the compound eluting agent is 0.2/3g/L, the concentration of the alkyl glycoside in the compound eluting agent is 20/3g/L, which is the preferable compound ratio;
when the concentration of the citric acid in the compound eluting lotion is 0.2/2g/L, the concentration of the alkyl glycoside in the compound eluting lotion is 10/2 g/L;
when the concentration of the citric acid in the compound eluting lotion is 0.4/3g/L, the concentration of the alkyl glycoside in the compound eluting lotion is 10/3 g/L.
The compound eluent is prepared by compounding 0.2g/L citric acid solution and 10.0g/L alkyl glycoside solution according to the volume ratio of (1:2) - (2: 1).
The alkyl glycoside is selected from one or more of APG0810, APG0814 or APG 1214.
The application of the compound eluting agent in repairing polycyclic aromatic hydrocarbon contaminated soil specifically comprises the following steps:
(1) weighing a soil sample containing polycyclic aromatic hydrocarbon after pretreatment, adding a compound eluent and uniformly mixing to obtain a repair sample;
(2) placing the uniformly mixed repairing sample obtained in the step (1) in a constant-temperature oscillation box for uniform oscillation reaction to ensure that the soil is fully contacted with the compound eluting agent;
(3) in the oscillation reaction process, a part of the repair sample is taken out at each set time point, filtrate and filter residue are respectively obtained after filtration, then the concentration of polycyclic aromatic hydrocarbon in the filtrate is measured, and the filter residue basically remains in the filter head.
In the step (1), the pretreatment comprises the following specific processes: the soil samples were air dried, defoliated and crushed stone removed and ground.
After grinding, the mixture is sieved by a 60-mesh sieve.
In the step (1), the polycyclic aromatic hydrocarbon is selected from one or more of naphthalene, anthracene, phenanthrene or benzo [ a ] pyrene.
If the test is verified, after grinding, the polycyclic aromatic hydrocarbon is dissolved in an organic solvent to form a polycyclic aromatic hydrocarbon solution, the polycyclic aromatic hydrocarbon solution and a soil sample are mixed, then the mixture is placed in a constant-temperature oscillation box to be oscillated and mixed uniformly, then the mixture is placed in a fume hood to volatilize the organic solvent, and finally aging is carried out.
The organic solvent is acetone.
The shaking and mixing temperature is 20 ℃, the shaking and mixing time is one week, the aging temperature is 4 ℃, and the aging time is two weeks.
In the step (1), the soil sample contains 78.3-113.2 mg/kg of polycyclic aromatic hydrocarbon.
In the step (1), the dosage of the compound eluting agent is 10-20 mL of the compound eluting agent used for 1g of soil.
In the step (2), the oscillating speed is 120-200 r/min, and the reaction time is 48-72 h.
In the step (3), a 0.45 μm filter head is adopted for filtration.
In the step (3), the sampling time points are 0.5, 1, 2, 4, 6, 12, 24 and 48 h.
According to the invention, a citric acid solution with low concentration and an alkyl glycoside solution which is easy to biodegrade are mixed to be used as a compound eluting agent. On the one hand, citric acid contains carboxyl and hydroxyl group, when adding them in polluting soil, can promote polycyclic aromatic hydrocarbon desorption from soil, make by fixed adsorbed polycyclic aromatic hydrocarbon enter into solution, and low concentration citric acid can destroy the "bond bridge" between Soil Organic Matter (SOM) and the soil mineral, thereby form Dissolubility Organic Matter (DOM), DOM can compete with the soil mineral and adsorb polycyclic aromatic hydrocarbon, and then reduce the absorption of soil to polycyclic aromatic hydrocarbon, and the polycyclic aromatic hydrocarbon that adsorbs on DOM can follow DOM and enter into aqueous phase. On the other hand, the alkyl glycoside is a biosurfactant, has the characteristic of easy biodegradation, has a good solubilizing effect on organic matters, enters soil particles after the alkyl glycoside in the solution is adsorbed by soil, causes the expansion of SOM, reduces the surface tension between the SOM and water phase, and promotes the desorption of the polycyclic aromatic hydrocarbon.
Compared with the prior art, the invention has the following advantages and positive effects: firstly, the low-concentration citric acid solution and the alkyl glycoside solution are compounded, so that the removal rate of the polycyclic aromatic hydrocarbon can reach over 72.1 percent and can reach 88.4 percent to the maximum; the compound eluent can overcome the problems of soil acidification and the like caused by over-strong acidity of high-concentration citric acid, is alkalescent or neutral, and has small influence on the physical and chemical properties of soil; the ingredients of the compound eluent used by the invention are low-concentration citric acid solution and alkyl glycoside solution, both the citric acid solution and the alkyl glycoside solution have biodegradability and cannot cause secondary pollution, and because the citric acid has stronger acidity, a large amount of citric acid is added into soil to cause acidification of the soil, and in consideration of practical application, the compound eluent only adopts the low-concentration citric acid and can also realize the remediation effect; the compound eluent used in the invention has low cost, greatly reduces the treatment cost and is easy to popularize and use; the process of the invention has simple operation and convenient operation, and does not need to adjust the pH value of the soil in the operation process.
Drawings
FIG. 1 is a graph showing the relationship between the removal rate of naphthalene in soil A and the complex ratio of naphthalene in example 1 (t: 48 h);
FIG. 2 is a graph showing the relationship between the removal rate of naphthalene in soil B and the complex ratio in example 2 (t: 48 h);
FIG. 3 is a graph showing the relationship between the removal rate of naphthalene in soil C and the complex ratio in example 3 (t: 48 h);
FIG. 4 is a graph of the removal rate of naphthalene in different soils in example 4 (t 48 h);
FIG. 5 is a graph showing the removal rate of naphthalene in soil D according to example 5 with time;
FIG. 6 is a graph showing the removal rate of naphthalene in soil E with time in example 6;
fig. 7 is a graph showing the relationship between the removal rate of phenanthrene in soil C and different compounding ratios in example 7 (t ═ 48 h).
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Reagents and equipment used in the invention are conventional in the art unless otherwise specified.
The compound eluent for repairing polycyclic aromatic hydrocarbon contaminated soil comprises solute and solvent, wherein the solute is citric acid and alkyl glycoside, the concentration of the citric acid in the compound eluent is (0.2/3-0.4/3) g/L, the concentration of the alkyl glycoside in the compound eluent is (10/3-20/3) g/L, and the solvent is ultrapure water.
The relevant physicochemical properties of the soil without polycyclic aromatic hydrocarbon contamination used in this example are shown in table 1, where soil a was taken from a certain plot in the pluronic area in shanghai city, and soil B and soil C were taken from a certain plot in the calming area in shanghai city, and these three soil samples were initially free of polycyclic aromatic hydrocarbon contamination and then were treated by artificial contamination to contain polycyclic aromatic hydrocarbons.
TABLE 1 physicochemical Properties of the soil used
Example 1
The compound eluent is used for repairing polycyclic aromatic hydrocarbon contaminated soil (the contaminated soil is marked as soil A, and specific components and other performance data are detailed in table 1), and the compound eluent specifically comprises the following steps:
(1) the method comprises the steps of airing soil A, removing spoiled leaves and broken stones, grinding, screening by a 60-mesh sieve, dissolving 20mg of solid naphthalene in 160mL of acetone at room temperature, mixing acetone solution containing naphthalene with 200g of soil A, oscillating and uniformly mixing in a constant-temperature oscillation box at 20 ℃ for one week, placing in a ventilation cabinet so as to volatilize acetone, and aging artificially contaminated soil at 4 ℃ for two weeks for use.
(2) Mixing a citric acid solution (the solvent is ultrapure water, the same below) with the concentration of 0.2g/L and an alkyl glycoside APG0814 solution (the solvent is ultrapure water, the same below) with the concentration of 10.0g/L according to the volume ratio of 1:2, 1:1 or 2:1 to respectively serve as a compound eluent I, a compound eluent II and a compound eluent III, namely the compound eluent I has the concentration of citric acid of 0.2/3g/L and the concentration of alkyl glycoside of 20/3g/L, the compound eluent II has the concentration of citric acid of 0.2/2g/L and the concentration of alkyl glycoside of 10/2g/L, and the compound eluent III has the concentration of citric acid of 0.4/3g/L and the concentration of alkyl glycoside of 10/3 g/L.
(3) Accurately weighing three 10g soil A samples with naphthalene concentration of 100mg/kg in a 100mL reactor, and respectively mixing the three samples according to the solid-liquid ratio of 1: and 10, adding 100mL of compound eluent I, compound eluent II and compound eluent III to obtain a repair sample, and then placing the reactor in a constant-temperature oscillation box at 20 ℃ to perform uniform oscillation reaction for 48 hours at a speed of 120 r/min.
(4) In the oscillation process, at set time points of 0.5, 1, 2, 4, 6, 12, 24 and 48 hours respectively, 1mL of the repair sample is taken out, the repair sample is filtered by a 0.45 mu m filter head to obtain filtrate and filter residue respectively, the concentration of naphthalene in the filtrate is measured, and after the compound eluting agents I, II and III are added and oscillated for 48 hours, the naphthalene concentration is 7.62mg/L, 7.28mg/L and 7.21mg/L respectively.
The experimental result shows that under the condition, the removal rate of the compound eluent I to naphthalene (the calculation formula of the removal rate is that the removal rate is naphthalene concentration at a set time point/initial concentration of naphthalene, the following is the same) is 76.2%, the removal rate of the compound eluent II to naphthalene is 72.8%, and the removal rate of the compound eluent III to naphthalene is 72.1% under the condition of 48 hours, which is shown in figure 1 (the numerical value of the removal rate measured when only 48 hours is adopted in figure 1, which is for comparing the repairing effect of the compound eluent with different compound ratios on the soil A, and the volume ratio in figure 1 is the compound ratio of the citric acid solution and the alkyl glycoside solution, and the following is the same).
Example 2
The compound eluent is used for repairing polycyclic aromatic hydrocarbon contaminated soil (the contaminated soil is marked as soil B, and specific components and other performance data are detailed in table 1), and the compound eluent specifically comprises the following steps:
(1) air-drying the soil B, removing spoiled leaves and broken stones, grinding, sieving with a 60-mesh sieve, dissolving 20mg of solid naphthalene in 160mL of acetone at room temperature, mixing the acetone solution containing naphthalene with 200g of soil B, uniformly mixing in a constant-temperature oscillation box at 20 ℃ for one week, placing in a fume hood so as to volatilize acetone, and aging the artificially contaminated soil at 4 ℃ for two weeks for use.
(2) Mixing a citric acid solution with a concentration of 0.2g/L and an alkyl glycoside APG0814 solution with a concentration of 10.0g/L according to a volume ratio of 1:2, 1:1 or 2:1 to respectively serve as a compound eluent I, a compound eluent II and a compound eluent III, namely, in the compound eluent I, the concentration of citric acid is 0.2/3g/L, the concentration of alkyl glycoside is 20/3g/L, in the compound eluent II, the concentration of citric acid is 0.2/2g/L, the concentration of alkyl glycoside is 10/2g/L, in the compound eluent III, the concentration of citric acid is 0.4/3g/L, and the concentration of alkyl glycoside is 10/3 g/L.
(3) Accurately weighing three 10g soil B samples with naphthalene concentration of 100mg/kg in a 100mL reactor, and respectively mixing the three samples according to the solid-liquid ratio of 1: and 10, adding 100mL of a compound eluent I, a compound eluent II and a compound eluent III to obtain a repair sample, and then placing the reactor in a constant-temperature oscillation box at 20 ℃ to perform uniform oscillation reaction for 48 hours at a speed of 120 r/min.
(4) In the oscillation process, at set time points of 0.5, 1, 2, 4, 6, 12, 24 and 48 hours respectively, 1mL of the repair sample is taken out, the repair sample is filtered by a 0.45 mu m filter head to obtain filtrate and filter residue respectively, the concentration of naphthalene in the filtrate is measured, and after the compound eluting agents I, II and III are added and oscillated for 48 hours, the naphthalene concentration is 7.98mg/L, 7.43mg/L and 7.38mg/L respectively.
The experimental result shows that under the condition, the removal rate of the compound eluent I on naphthalene is 79.8 percent, the removal rate of the compound eluent II on naphthalene is 74.3 percent, and the removal rate of the compound eluent III on naphthalene is 73.8 percent, as shown in figure 2 (the numerical value of the removal rate measured when only 48 hours is adopted in figure 2, and the numerical value is used for comparing the repairing effect of the compound eluents with different compound ratios on soil B).
Example 3
The compound eluent is used for repairing polycyclic aromatic hydrocarbon contaminated soil (the contaminated soil is marked as soil C, and specific components and other performance data are detailed in table 1), and the compound eluent specifically comprises the following steps:
(1) the soil C is dried in the air, the spoiled leaves and the broken stones are removed, the ground soil C is sieved by a 60-mesh sieve, 20mg of solid naphthalene is dissolved in 160mL of acetone at room temperature, the acetone solution containing the naphthalene is mixed with 200g of the soil C and then is uniformly mixed in a constant-temperature oscillation box at 20 ℃ for one week, then the mixture is placed in a ventilation cabinet so that the acetone is volatilized, and the artificially polluted soil is aged for two weeks at 4 ℃ for use.
(2) Mixing a citric acid solution with a concentration of 0.2g/L and an alkyl glycoside APG0814 solution with a concentration of 10.0g/L according to a volume ratio of 1:2, 1:1 or 2:1 to respectively serve as a compound eluent I, a compound eluent II and a compound eluent III, namely, in the compound eluent I, the concentration of citric acid is 0.2/3g/L, the concentration of alkyl glycoside is 20/3g/L, in the compound eluent II, the concentration of citric acid is 0.2/2g/L, the concentration of alkyl glycoside is 10/2g/L, in the compound eluent III, the concentration of citric acid is 0.4/3g/L, and the concentration of alkyl glycoside is 10/3 g/L.
(3) Accurately weighing three 10g soil C samples with naphthalene concentration of 100mg/kg in a 100mL reactor, and respectively weighing the three samples according to the solid-to-liquid ratio of 1: and 10, adding 100mL of compound eluent I, compound eluent II and compound eluent III to obtain a repair sample, and then placing the reactor in a constant-temperature oscillation box at 20 ℃ to perform uniform oscillation reaction for 48 hours at a speed of 120 r/min.
(4) In the oscillation process, at set time points of 0.5, 1, 2, 4, 6, 12, 24 and 48 hours respectively, 1mL of the repair sample is taken out, the repair sample is filtered by a 0.45 mu m filter head to obtain filtrate and filter residue respectively, the concentration of naphthalene in the filtrate is measured, and after the compound eluting agents I, II and III are added and oscillated for 48 hours, the naphthalene concentration is 8.34mg/L, 7.95mg/L and 7.86mg/L respectively.
The experimental result shows that under the condition, the removal rate of the compound eluent I to naphthalene is 83.4 percent, the removal rate of the compound eluent II to naphthalene is 79.5 percent, and the removal rate of the compound eluent III to naphthalene is 78.6 percent, wherein the removal rates are shown in figure 3 (the numerical value of the removal rate measured when only 48 hours is adopted in figure 3, and the numerical value is used for comparing the repairing effect of the compound eluents with different compound ratios on the soil C).
Comparative examples 1, 2, 3 gave: the removal rate of the compound eluent on naphthalene is reduced along with the increase of the content of clay particles in soil; the compound eluting agent has the highest efficiency when the volume ratio of the citric acid to the alkyl glycoside is 1: 2.
Example 4
The compound eluent is used for repairing polycyclic aromatic hydrocarbon contaminated soil (three kinds of contaminated soil are taken and are respectively marked as soil A, soil B and soil C, and specific components and other performance data are detailed in table 1), and the compound eluent specifically comprises the following steps:
(1) the method comprises the steps of airing soil A, removing spoiled leaves and broken stones, grinding the soil A, screening the ground soil A through a 60-mesh sieve, dissolving 60mg of solid naphthalene in 480mL of acetone at room temperature, obtaining a uniformly mixed acetone solution containing naphthalene after the solid naphthalene is completely dissolved, evenly dividing the acetone solution into three parts, mixing 160mL of the acetone solution containing naphthalene with 200g of soil A, soil B and soil C respectively, then oscillating the mixture in a constant-temperature oscillation box at 20 ℃ for uniformly mixing the mixture for one week, then placing the mixture in a ventilation cabinet so as to volatilize acetone, and aging artificially contaminated soil for two weeks at 4 ℃ for use.
(2) Mixing a citric acid solution with the concentration of 0.2g/L and an alkyl glycoside APG0814 solution with the concentration of 10.0g/L according to the volume ratio of 1:2 to obtain the compound eluent, namely, the concentration of citric acid is 0.2/3g/L and the concentration of alkyl glycoside is 20/3 g/L.
(3) Accurately weighing 5g of soil A sample with naphthalene concentration of 100mg/kg in a 100mL reactor, and mixing the soil A sample with the naphthalene concentration of 100mg/kg according to a solid-liquid ratio of 1: and adding 100mL of compound eluting agent into 20 to obtain a repair sample, and then placing the reactor into a constant-temperature oscillation box at 20 ℃ to perform oscillation reaction at a constant speed of 120r/min for 48 hours.
(4) In the oscillation process, at set time points of 0.5, 1, 2, 4, 6, 12, 24 and 48 hours respectively, 1mL of the repair sample is taken out, the repair sample is filtered by a 0.45 mu m filter head to obtain filtrate and filter residue respectively, the concentration of naphthalene in the filtrate is measured, and the concentration of naphthalene in soil A, B, C after the compound eluent is added and oscillated for 48 hours is 8.36mg/L, 8.59mg/L and 8.84mg/L respectively.
The experimental result shows that under the condition, the removal rate of the compound eluent on naphthalene in soil A is 83.6%, the removal rate on naphthalene in soil B is 85.9%, and the removal rate on naphthalene in soil C is 88.4%, as shown in figure 4 (the numerical value of the removal rate measured when only 48 hours is adopted in figure 4, and the numerical value is used for comparing the repairing effect of the compound eluent with the optimal compound ratio on different soils).
Comparative examples 1, 2, 3, 4, gave: the removal rate of the compound eluent on naphthalene is reduced along with the increase of the clay content of soil; the compound eluent has the highest efficiency when the volume ratio of the citric acid to the alkyl glycoside is 1: 2; the higher the solid-liquid ratio is, the higher the removal rate of naphthalene by the compound eluting agent is.
The relevant physicochemical properties of the actual contaminated soils used in examples 5 and 6 below are given in table 2 below, in which soil D was taken from a certain territory of the shanghai city pruurban and soil E was taken from a certain territory of the shanghai city minwhorl.
TABLE 2 physicochemical properties of the soil used
Example 5
The compound eluent is used for repairing polycyclic aromatic hydrocarbon contaminated soil (the contaminated soil is recorded as soil D, and specific components and other performance data are detailed in table 2), and the compound eluent specifically comprises the following steps:
(1) and (3) drying the soil D, removing the spoiled leaves and the broken stones, grinding and then sieving by a 60-mesh sieve.
(2) Mixing a citric acid solution with the concentration of 0.2g/L and an alkyl glycoside APG0814 solution with the concentration of 10.0g/L according to the volume ratio of 1:2 to obtain the compound eluent, namely, the concentration of citric acid is 0.2/3g/L and the concentration of alkyl glycoside is 20/3 g/L.
(3) Accurately weighing 5g of soil D sample in a 100mL reactor, and mixing the soil D sample with the solid-liquid ratio of 1: and adding 100mL of compound eluent into 20 to obtain a repaired sample, and then placing the reactor into a constant-temperature oscillation box at 20 ℃ to perform uniform oscillation reaction for 48 hours.
(4) In the oscillation process, at set time points of 0.5, 1, 2, 4, 6, 12, 24 and 48 hours respectively, 1mL of the repair sample is taken out, filtered by a 0.45 μm filter head to obtain filtrate and filter residue respectively, and the concentration of naphthalene in the filtrate is measured.
The experimental result shows that the removal rate of the compound eluent on naphthalene under the condition is 82.3%, and the change of the removal rate of naphthalene in soil D along with time is shown in figure 5.
Example 6
The compound eluent is used for repairing polycyclic aromatic hydrocarbon contaminated soil (the contaminated soil is recorded as soil E, and specific components and other performance data are detailed in a table 2), and specifically comprises the following steps:
(1) and (3) drying the soil E, removing the rotten leaves and the broken stones, grinding and then sieving by using a 60-mesh sieve.
(2) Mixing a citric acid solution with the concentration of 0.2g/L and an alkyl glycoside APG0814 solution with the concentration of 10.0g/L according to the volume ratio of 1:2 to obtain the compound eluent, namely, the concentration of citric acid is 0.2/3g/L and the concentration of alkyl glycoside is 20/3 g/L.
(3) Accurately weighing 5g of soil sample E in a 100mL reactor, and mixing the soil sample E and the soil sample E according to a solid-liquid ratio of 1: and adding 100mL of compound eluting agent into 20 to obtain a repair sample, and then placing the reactor into a constant-temperature oscillation box at 20 ℃ to perform uniform-speed oscillation reaction for 48 hours.
(4) In the oscillation process, at set time points of 0.5, 1, 2, 4, 6, 12, 24 and 48 hours respectively, 1mL of the repair sample is taken out, filtered by a 0.45 μm filter head to obtain filtrate and filter residue respectively, and the concentration of naphthalene in the filtrate is measured.
The experimental result shows that the removal rate of the compound eluent on naphthalene under the condition is 80.7%, and the time-dependent change of the removal rate of naphthalene in soil E is shown in figure 6.
Comparative examples 1, 2, 3, 4, 5, 6, gave: the removal rate of the compound eluent on naphthalene is reduced along with the increase of the content of clay particles in soil; the compound eluent has the highest efficiency when the volume ratio of the citric acid to the alkyl glycoside is 1: 2; the higher the solid-liquid ratio is, the higher the removal rate of the naphthalene by the compound eluent is; the actual polluted soil has long pollution time, so the removal rate of the compound eluting agent to naphthalene is slightly lower than that of the artificially polluted soil.
Example 7
The compound eluent is used for repairing polycyclic aromatic hydrocarbon contaminated soil (the contaminated soil is recorded as soil C, and specific components and other performance data are detailed in table 1), and specifically comprises the following steps:
(1) the soil C is dried in the air, the spoiled leaves and the broken stones are removed, the ground soil C is sieved by a 60-mesh sieve, 2mg of solid phenanthrene is dissolved in 160mL of acetone at room temperature, the acetone solution containing the phenanthrene is mixed with 200g of the soil C and then is uniformly mixed in a constant-temperature oscillation box at 20 ℃ for one week, then the mixture is placed in a ventilation cabinet so that acetone can volatilize, and the artificially contaminated soil is aged for two weeks at 4 ℃ for use.
(2) Mixing a citric acid solution with a concentration of 0.2g/L and an alkyl glycoside APG0814 solution with a concentration of 10.0g/L according to a volume ratio of 1:2, 1:1 or 2:1 to respectively serve as a compound eluent I, a compound eluent II and a compound eluent III, namely, in the compound eluent I, the concentration of citric acid is 0.2/3g/L, the concentration of alkyl glycoside is 20/3g/L, in the compound eluent II, the concentration of citric acid is 0.2/2g/L, the concentration of alkyl glycoside is 10/2g/L, in the compound eluent III, the concentration of citric acid is 0.4/3g/L, and the concentration of alkyl glycoside is 10/3 g/L.
(3) Accurately weighing three 10g of soil C samples with phenanthrene concentration of 10mg/kg in a 100mL reactor, and respectively mixing the three samples according to a solid-liquid ratio of 1: and 10, adding 100mL of compound eluent I, compound eluent II and compound eluent III to obtain a repair sample, and then placing the reactor in a constant-temperature oscillation box at 20 ℃ to perform uniform oscillation reaction for 48 hours at a speed of 120 r/min.
(4) In the oscillation process, at set time points of 0.5, 1, 2, 4, 6, 12, 24 and 48 hours respectively, taking out 1mL of the repair sample, filtering by a 0.45-micrometer filter head to obtain filtrate and filter residue respectively, measuring the concentration of phenanthrene in the filtrate, and after adding the compound eluting agents I, II and III and oscillating for 48 hours, respectively, the concentration of phenanthrene is 0.792mg/L, 0.752mg/L and 0.734 mg/L.
The experimental result shows that under the condition, the removal rate of the compound eluent I to phenanthrene is 79.2 percent, the removal rate of the compound eluent II to phenanthrene is 75.2 percent, and the removal rate of the compound eluent III to phenanthrene is 73.4 percent, as shown in figure 7 (the numerical value of the removal rate measured when only 48 hours is adopted in figure 1, and the numerical value is used for comparing the repairing effect of the compound eluents with different compound ratios on the soil C).
Comparative examples 1, 2, 3, 4, 5, 6, 7 gave: the removal rate of the compound eluent on polycyclic aromatic hydrocarbons such as naphthalene and the like is reduced along with the increase of the content of clay in soil; the compound eluent has the highest efficiency when the volume ratio of the citric acid to the alkyl glycoside is 1: 2; the higher the solid-liquid ratio is, the higher the removal rate of polycyclic aromatic hydrocarbons such as naphthalene by the compound eluting agent is; the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and the like in the actual polluted soil is slightly lower than that in the artificially polluted soil due to long pollution time; the higher the number of polycyclic aromatic hydrocarbon rings is, the more difficult the polycyclic aromatic hydrocarbon rings are to be desorbed from soil, so that the compound eluting agent has higher removal efficiency on the polycyclic aromatic hydrocarbon rings with low rings.
Example 8
This example provides a specific implementation of the compound eluent for repairing polycyclic aromatic hydrocarbon contaminated soil, which is the same as example 7 except that the alkyl glycoside is APG0810, the oscillation speed is 200r/min during the repairing reaction, and the reaction time is 60 h.
Example 9
This example provides a specific implementation of the compound eluent for repairing polycyclic aromatic hydrocarbon contaminated soil, which is the same as example 7 except that the alkyl glycoside is APG1214, the oscillation speed is 150r/min during the repairing reaction, and the reaction time is 72 h.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (8)
1. The compound eluent for repairing polycyclic aromatic hydrocarbon-polluted soil is characterized by comprising a solute and a solvent, wherein the solute is composed of citric acid and alkyl glycoside, the concentration of the citric acid in the compound eluent is (0.2/3-0.4/3) g/L, and the concentration of the alkyl glycoside in the compound eluent is (10/3-20/3) g/L;
the solvent is ultrapure water;
when the concentration of the citric acid in the compound eluting lotion is 0.2/3g/L, the concentration of the alkyl glycoside in the compound eluting lotion is 20/3 g/L;
when the concentration of the citric acid in the compound eluting lotion is 0.2/2g/L, the concentration of the alkyl glycoside in the compound eluting lotion is 10/2 g/L;
when the concentration of the citric acid in the compound eluting lotion is 0.4/3g/L, the concentration of the alkyl glycoside in the compound eluting lotion is 10/3 g/L.
2. The application of the compound eluting agent as defined in claim 1 in repairing polycyclic aromatic hydrocarbon contaminated soil is characterized in that the application specifically comprises the following steps:
(1) weighing a soil sample containing polycyclic aromatic hydrocarbon after pretreatment, adding a compound eluent and uniformly mixing to obtain a restoration sample;
(2) placing the uniformly mixed repairing sample obtained in the step (1) in a constant-temperature oscillation box for uniform oscillation reaction to ensure that the soil is fully contacted with the compound eluting agent;
(3) in the oscillating reaction process, taking out a part of the repair sample at each set time point, filtering to obtain filtrate and filter residues respectively, and then measuring the concentration of the polycyclic aromatic hydrocarbon in the filtrate.
3. The application of the compound eluent in repairing polycyclic aromatic hydrocarbon-contaminated soil according to claim 2, wherein in the step (1), the pretreatment comprises the following specific steps: the soil samples were air dried, defoliated and crushed stone removed and ground.
4. The application of the compound eluent in repairing polycyclic aromatic hydrocarbon contaminated soil according to claim 3, wherein the compound eluent is sieved by a 60-mesh sieve after being ground.
5. The application of the compound eluent in remediation of soil polluted by polycyclic aromatic hydrocarbons as claimed in claim 2, wherein in step (1), the polycyclic aromatic hydrocarbons are selected from one or more of naphthalene, anthracene, phenanthrene or benzo [ a ] pyrene.
6. The application of the compound eluent in remediation of polycyclic aromatic hydrocarbon-contaminated soil according to claim 2, wherein in the step (1), the amount of the compound eluent is 10-20 mL for 1g of soil.
7. The application of the compound eluent in repairing polycyclic aromatic hydrocarbon-polluted soil according to claim 2, wherein in the step (2), the oscillation speed is 120-200 r/min, and the reaction time is 48-72 h.
8. The application of the compound eluent in repairing polycyclic aromatic hydrocarbon-contaminated soil according to claim 2, wherein in the step (3), a 0.45 μm filter head is adopted for filtration.
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