CN115739957A - Method and device for repairing polycyclic aromatic hydrocarbon polluted soil through cyclic synergism of surfactant - Google Patents
Method and device for repairing polycyclic aromatic hydrocarbon polluted soil through cyclic synergism of surfactant Download PDFInfo
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Abstract
The invention provides a method and a device for repairing polycyclic aromatic hydrocarbon contaminated soil by utilizing a green surfactant to realize cyclic synergism, and relates to the technical field of soil repair, wherein the method comprises the following steps: adding a proper proportion of green surfactant solution into the polycyclic aromatic hydrocarbon polluted soil for leaching to enhance the dissolution of the polycyclic aromatic hydrocarbon and quickly desorb the polycyclic aromatic hydrocarbon from the soil. After leaching, extracting and collecting the washing liquid, adding a biological agent into the soil, and maintaining and degrading the polycyclic aromatic hydrocarbon and the residual surfactant; persulfate/biochar with proper proportion is added into the washing liquid to degrade the polycyclic aromatic hydrocarbon in the washing liquid, and the washing liquid containing the surfactant is recycled to circularly carry out secondary solubilization desorption or solubilization desorption of polluted soil in the next batch. The surfactant used in the invention is a green surfactant, has low toxicity and is beneficial to biodegradation; the persulfate/charcoal oxidation system is utilized to degrade the eluted polycyclic aromatic hydrocarbon, so that the recovery and the recycling of the surfactant can be realized, and the cost is saved.
Description
Technical Field
The invention belongs to the technical field of soil remediation, and particularly relates to a method and a device for remediating polycyclic aromatic hydrocarbon contaminated soil through cyclic synergism of a surfactant.
Background
Polycyclic Aromatic Hydrocarbons (PAHs) are used as common persistent organic pollutants, and are generally formed by connecting two or more benzene rings through carbon atoms, and the common polycyclic aromatic hydrocarbons include naphthalene, phenanthrene, anthracene, benzo [ a ] pyrene and the like, are difficult to biodegrade due to stable structure and poor water solubility, have strong "triorganism" (teratogenicity, carcinogenicity and mutagenicity), and are listed in a list of persistent organic pollutants which are preferably controlled by the U.S. environmental protection agency as early as 1982; china also lists polycyclic aromatic hydrocarbons in the list of environment-preferred detection pollutants. The toxicity of the polycyclic aromatic hydrocarbon is increased along with the increase of the number of benzene rings in a certain range, and the polycyclic aromatic hydrocarbon with low ring (less than or equal to 3 rings) is easy to degrade; and the polycyclic aromatic hydrocarbon with high ring (ring being more than or equal to 4) has lower solubility in water, firmer adsorbed organic matter and lower biodegradability, and the half-life period in soil can reach half a year.
In recent years, pollution control and treatment of polycyclic aromatic hydrocarbons in soil are gradually concerned by researchers at home and abroad. At present, three methods of physical remediation, chemical remediation and biological remediation are mainly adopted as soil remediation modes, wherein the chemical remediation method is widely applied due to the advantages of easiness in operation, high efficiency, short period and the like. The chemical leaching remediation technology in chemical remediation is paid much attention due to low cost, and becomes one of the hot spots and development directions of rapid remediation research of the polycyclic aromatic hydrocarbon contaminated soil in the field. The currently adopted eluent mainly comprises a chelating agent and a surfactant, wherein the chelating agent and metal ions are easy to form stable chelate, and can be used for repairing heavy metal polluted soil; the surfactant has a solubilizing effect on organic pollutants and is widely applied to remediation of organic polluted soil.
Surfactants can enhance the desorption and elution of Polycyclic Aromatic Hydrocarbons (PAHs) from the solid to the aqueous phase by partitioning the PAHs into the hydrophobic core of the surfactant micelles to exceed the Critical Micelle Concentration (CMC) to increase the solubility of the PAHs. After the single surfactant reaches the critical micelle concentration value, the surfactant concentration is continuously increased, so that only the micelle is increased or the number of the micelle is increased, but the number of single molecules of the surfactant in the solution is not increased any more, and the solubilizing effect of the single surfactant on the polycyclic aromatic hydrocarbon is limited. Common surfactants such as Tween80 (Tween 80), triton-100 (TX-100), sodium Dodecyl Benzene Sulfonate (SDBS), sodium Dodecyl Sulfate (SDS), and the like can desorb polycyclic aromatic hydrocarbons from soil, but most of the surfactants are amphoteric molecules, and are easy to adsorb and difficult to desorb by soil while removing pollutants, thereby causing secondary pollution. In addition, the surfactant can form composite pollution with metal pollutants in soil or has a bactericidal effect, so that the bioavailability of the soil is greatly reduced.
The anionic surfactant fatty acid Methyl Ester Sulfonate (MES) has low irritation and toxicity and excellent biocompatibility, the nonionic surfactant alkyl glycoside (APG) is non-toxic, non-irritant and easily biodegradable, and the MES-APG anionic-nonionic surfactant is compounded, so that the surfactant has lower surface tension and critical micelle concentration, the solubilizing capability of the surfactant on pollutants is greatly improved, and the biological degradation is prevented from being influenced by adverse effects on biological inoculants. Meanwhile, in order to save the cost of the surfactant, the persulfate oxidation system is combined to carry out oxidative degradation on the polycyclic aromatic hydrocarbon in the eluent, the surfactant is further recovered, and the solubilization and desorption of the polycyclic aromatic hydrocarbon in the secondary or multiple polluted soil can be carried out. On the basis, a solubilizing desorption-degradation-surfactant recovery integrated device is designed for realizing the cyclic synergistic remediation of the polycyclic aromatic hydrocarbon polluted soil by using the surfactant in one step.
Disclosure of Invention
Aiming at the existing problems of soil remediation, the invention provides a method for remedying polycyclic aromatic hydrocarbon contaminated soil by the cyclic synergism of a surfactant, which comprises the following steps:
s1, arranging a leaching pipeline and a spraying device above the polluted soil, arranging extraction wells at the periphery of the polluted soil, and adding a prepared 1-6 g/L compound surfactant into the leaching pipeline through a pressure pump to enable the compound surfactant to enter the polluted soil through the spraying device.
S2, leaching time is about 48h, and the water-soil ratio is 5mL:1 g-30 mL:1g, after the leaching is finished, the washing liquid of the leached soil is extracted and collected by a vacuum suction pump.
And S3, adding biological agents (bacillus subtilis and pseudomonas aeruginosa) into the soil, uniformly mixing the washed soil and the agents in a turning mode, maintaining for 10 days, further repairing the eluted soil, and removing the residual Polycyclic Aromatic Hydrocarbons (PAHs) in the soil.
And S4, adding 0.5-2 mmol/L Persulfate (PS) and 100mg/L, 250mg/L, 500mg/L, 750mg/L, 1000mg/L, 2000mg/L and 3000mg/L biochar into the leacheate, and stirring for about 2 hours to degrade PAHs in the leacheate.
And S5, measuring the content of the polycyclic aromatic hydrocarbon PAHs in the degraded eluent by liquid phase, basically degrading the polycyclic aromatic hydrocarbon PAHs completely, continuously spraying the eluent into the polluted soil, and circularly eluting the polycyclic aromatic hydrocarbon PAHs.
Preferably, in step S3, a biological agent is added; the biological agent is any one of bacillus subtilis and pseudomonas aeruginosa.
Preferably, a degradation system is simultaneously constructed in the step S3, and the degradation system is 0.1-3 g/L of biochar and 0.5-2 mmol/L of Persulfate (PS).
Preferably, the compound surfactant is a compound of fatty acid Methyl Ester Sulfonate (MES) and alkyl glycoside (APG), and the volume ratio of the compound is 7:1, wherein the fatty acid methyl ester sulfonate is also called alpha-sulfo fatty acid methyl ester (mono), which is abbreviated as MES (methyl ester sulfonate) in English, and is also abbreviated as alpha-SFMeNa (sodium alpha-sulfo fatty acid methyl ester), which has the general formula of RCH (SO) 3 Na)COOCH 3 (ii) a Alkyl glycosides are also known as alkyl polyglycosides, which are abbreviated in english as APG (alkyl polyglycoside).
The polycyclic aromatic hydrocarbon is benzo [ a ] pyrene, phenanthrene and naphthalene.
The remediation method is in-situ remediation of soil, the compound surfactant promotes pollutants to be desorbed from the soil and transferred to a surfactant phase, and the compound surfactant has the functions of solubilization and desorption;
the method combining the compound surfactant and biodegradation is greener.
The second aspect of the invention provides a preparation method of an environment-friendly compound surfactant, which comprises the steps of mixing fatty acid Methyl Ester Sulfonate (MES) and alkyl glycoside (APG) according to an optimal compound ratio (7.
Specifically, after the surfactant reaches the critical micelle concentration value, the concentration of the surfactant is continuously increased, only the number of micelles is increased or increased, but the number of single molecules of the surfactant in the solution is not increased any more, and the solubilizing effect of the single surfactant on the polycyclic aromatic hydrocarbon is limited, so that the surfactant is compounded, so that the surfactant has lower surface tension and critical micelle concentration, and the solubilizing capability of the surfactant on pollutants is greatly improved.
In each compound system, the anion-nonionic surfactant compound can form mixed micelle, and the adsorption of the surfactant in soil is reduced.
Preferably, the compound surfactant is prepared by compounding fatty acid methyl ester sodium sulfonate (MES) and alkyl glycoside (APG), both are environment-friendly, and the compound surfactant has small influence on the environment and is easy to biodegrade; the compounding method of the compound surfactant specifically comprises the following steps:
step p1. Determination of critical micelle concentration value (CMC) of a single surfactant using surface tension method:
in this example, the critical micelle concentration C of pure Alkylglycoside (APG) was determined 1 And critical gum of pure sodium fatty acid Methyl Ester Sulfonate (MES)Beam density value C 2 ；
Step P2. Calculating the critical micelle concentration value C of the compound surfactant id ：
Wherein alpha is 1 Denotes the molar fraction of alkyl glycosides (APG) in the surfactant mixture, C 1 Experimental Critical micelle concentration value (CMC), C, representing pure alkyl glycoside (APG) 2 The experimental critical micelle concentration value (CMC), C, representing pure sodium fatty acid Methyl Ester Sulfonate (MES) id The theoretical critical micelle concentration value (CMC) of the pure alkyl glycoside (APG) and the pure fatty acid methyl ester sodium sulfonate (MES) compounded surfactant is shown; x id1 Represents the mole fraction of the surfactant alkyl glycoside (APG) in the ideal mixed micelle;
step P3, determining the critical micelle concentration value of the compound surfactant through an experiment:
wherein, C 12 The experimental critical micelle concentration value (CMC) of the pure alkyl glycoside (APG) and the pure fatty acid methyl ester sodium sulfonate (MES) compounded surfactant is shown; x 1 Represents the micelle mole fraction of the surfactant alkyl glycoside (APG) in the mixed micelles;
the interaction parameter β is a parameter representing the nature and magnitude of the interaction between the surfactant components in the mixed micelles; for dimensionless parameters, the degree of deviation from the ideal mixing behavior is determined. Negative β indicates a synergistic effect by attraction, and positive β indicates an antagonistic effect by repulsion between surfactant molecules in the mixed micelle phase;
step P4. Knowing β and X 1 After the value of (a), the activity coefficient (f) of the surfactant alkyl glycoside (APG) in the mixed micelle was calculated 1 ) And the activity coefficient (f) of the surfactant sodium fatty acid Methyl Ester Sulfonate (MES) 2 ) Further calculating the micellization excess Gibbs free energy of the mixed micelle to determine the optimal compound ratio;
f 1 ＝exp[β(1-X 1 ) 2 ]
f 2 ＝exp[β(X 1 ) 2 ]
ΔG＝RT[X 1 lnf 1 +(1-X 1 )lnf 2 ]
ΔG E indicates the micellization excess Gibbs free energy, Δ G, of the mixed micelle E The values represent an indication of energy stability associated with mixed micelle formation.
When Δ G E When the value is negative, the energy stability of the mixed micelle is higher than that of a single surfactant micelle; Δ G E Positive values are the opposite.
According to the calculation results and assisted by experimental verification, MES, APG =7 and MES, APG = 1 are obtained as the optimal compounding ratio. The compound surfactant is obtained by compounding according to the compound ratio.
The third aspect of the invention provides an elution degradation device for circularly and synergistically repairing polycyclic aromatic hydrocarbon contaminated soil, which comprises: the rotating device is connected with the driving device, a peristaltic pump pipe is arranged above the rotating device, and the peristaltic pump pipe is connected with the degradation device; and a sponge impregnated with biochar is arranged in the degradation device and used for eluting pollutants in the eluent.
Preferably, the peristaltic pump tube comprises a peristaltic pump thereon.
The invention utilizes surfactant fatty acid methyl ester sodium sulfonate (MES) to play a role in repairing polycyclic aromatic hydrocarbon polluted soil, solves the problem of soil repair in the prior art, adopts environment-friendly, efficient and low-cost eluent fatty acid methyl ester sodium sulfonate (MES), and the fatty acid methyl ester sodium sulfonate (MES) is a product which is prepared by sulfonating and neutralizing fatty acid methyl ester serving as a raw material. The surfactant is a chemical substance which can remarkably reduce the surface tension of a solvent by adding a small amount of the surfactant and change the state of a system interface so as to generate the effects of wetting, dispersing and the like.
The molecular structure of the surfactant has amphipathy, one end is always a polar hydrophilic group, the other end is always a non-polar hydrocarbon chain, the structural characteristics enable the surfactant to have various effects of washing, solubilizing, wetting, dispersing, foaming, permeating, sterilizing and the like, and the application of the surfactant in the field of soil remediation is mainly the effects of washing, solubilizing, wetting, permeating and dispersing.
The specific structure of the surfactant competes strongly with Soil Organic Matter (SOM), incorporating Polycyclic Aromatic Hydrocarbons (PAHs) by forming micelles when the concentration is greater than the Critical Micelle Concentration (CMC) and the interfacial tension is reduced. The formed micelles can pass through the hydrophobic interior while the hydrophilic exterior contacts the aqueous phase to bind with Polycyclic Aromatic Hydrocarbons (PAHs), thereby increasing their movement into solution. The surfactant may enhance desorption and elution of Polycyclic Aromatic Hydrocarbons (PAHs) from the solid into the aqueous phase by partitioning the PAHs into the hydrophobic core of the surfactant micelles to exceed the Critical Micelle Concentration (CMC) to increase solubility of the PAHs. Usually, when organic contaminated soil is repaired, a surfactant solution is injected into soil to generate wetting and permeation effects, a hydrophilic group extends into a water phase, a hydrophobic group tends to be combined with hydrophobic organic pollutants or soil particles to form an adsorption film in directional arrangement, so that the solution is spread on the soil surface, the interfacial tension of solid phase-water and pollutant-water is reduced, the adhesion force of the pollutants on the soil surface is reduced, the dissolution of the pollutants in the soil is promoted, and the pollutants are eluted from the solid surface through washing effects, so that the aim of removing Polycyclic Aromatic Hydrocarbons (PAHs) is fulfilled. Therefore, at a low concentration level of the fatty acid methyl ester sodium sulfonate (MES), the monomer is firstly adsorbed on soil particles in an equatorial state by virtue of electrostatic interaction, so that the adsorption isotherm of the fatty acid methyl ester sodium sulfonate (MES) shows slow rise; with the continuous increase of the concentration of fatty acid methyl ester sodium sulfonate (MES) in the solution, the molecules of the MES are changed from an equatorial state to an upright state to form a semi-micelle structure on soil particles, and as the polycyclic aromatic hydrocarbon is a hydrophobic organic matter, the hydrophilic head faces to the solution at the moment, and the adsorption isotherm begins to rise rapidly; with the continuous rise of the concentration, molecules of the Polycyclic Aromatic Hydrocarbons (PAHs) are subjected to double-layer adsorption on soil particles due to hydrophobic association of hydrocarbon chains to form a complete surface micelle structure, which shows that an adsorption isotherm reaches a stable state, and the elution of the PAHs is completed. After the single surfactant reaches the critical micelle concentration value, the concentration of the surfactant is continuously increased, only the number of micelles is increased or increased, but the number of single molecules of the surfactant in the solution is not increased any more, and the solubilizing effect of the single surfactant on the polycyclic aromatic hydrocarbon is limited, so that the surfactant fatty acid Methyl Ester Sulfonate (MES) and the alkyl glycoside (APG) are compounded to have lower surface tension and critical micelle concentration, and the solubilizing capability of the surfactant on pollutants is greatly improved.
Drawings
FIG. 1 shows the influence of the concentration of a compound surfactant on the leaching effect of benzo [ a ] pyrene contaminated soil;
FIG. 2 is a graph showing the effect of biochar concentration on the degradation effect of an eluent;
FIG. 3 is a diagram of a cycle elution experimental apparatus.
Detailed Description
Example 1.1 a method for cyclic synergistic remediation of polycyclic aromatic hydrocarbon contaminated soil with a surfactant, comprising:
step 1, arranging a leaching pipeline and a spraying device above the soil polluted by Polycyclic Aromatic Hydrocarbons (PAHs), arranging extraction wells at the periphery of the polluted soil, and adding 1-6 g/L of prepared compound surfactant into the leaching pipeline through a pressure pump to enable the compound surfactant to enter the polluted soil through the spraying device.
Step 2, leaching for 48 hours, wherein the water-soil ratio is 5mL: after 1g of the washed soil is finished, the washing liquid of the washed soil is extracted and collected by a vacuum suction pump.
And 3, adding a biological agent (bacillus subtilis or pseudomonas aeruginosa) into the soil, uniformly mixing the washed soil and the biological agent in a turning manner, maintaining for 10 days, further repairing the eluted soil, and removing the residual PAHs in the soil.
And 4, adding 0.5-2 mmol/L Persulfate (PS) and 100mg/L, 250mg/L, 500mg/L, 750mg/L, 1000mg/L, 2000mg/L and 3000mg/L of biochar into the leacheate, stirring for about 2 hours, and degrading Polycyclic Aromatic Hydrocarbons (PAHs) in the leacheate.
And 5, measuring the content of Polycyclic Aromatic Hydrocarbons (PAHs) in the degraded eluent by liquid phase measurement, completely degrading, continuously spraying the eluent into the polluted soil, and circularly eluting the PAHs.
Example 1.2 method for repairing polycyclic aromatic hydrocarbon contaminated soil with cyclic synergism of surfactant, the same as example 1.1, except that the water-soil ratio in step 2 is 30mL:1g.
Example 1.3 method for repairing polycyclic aromatic hydrocarbon contaminated soil with cyclic synergism of surfactant, the same as example 1.1, except that the water-soil ratio in step 2 is 20mL:1g of the total weight of the composition.
Example 1.4 a method for remedying polycyclic aromatic hydrocarbon contaminated soil by surfactant cyclic synergism, which is the same as example 1.1, is different in that the water-soil ratio in the step 2 is 10mL:1g of the total weight of the composition.
Example 2.1 method for the cyclic synergistic remediation of polycyclic aromatic hydrocarbon contaminated soil with a surfactant:
50mL of a 6g/L reagent containing a built surfactant (MES: APG = 7. An excess of benzo [ a ] pyrene in dichloromethane was added to a clean glass bottle and blown dry with a nitrogen blower. Then, 20mL of prepared complex surfactant solutions with different concentrations are respectively added into the glass tube, and the glass tube is subjected to ultrasonic treatment for 30min to be uniformly mixed.
Sealing, placing in a constant temperature shaking table at 20 deg.C and 160r/min, shaking for 48 hr, taking out, centrifuging in a centrifuge at 3000r/min for 10min, taking out, standing for 30min, passing through 0.22 μm organic membrane, and placing in liquid phase vial to be tested.
Preparing 100mg/L phenanthrene standard solution, diluting according to steps, preparing a group of benzo [ a ] pyrene standard series solutions (0.05, 0.1, 0.5, 1, 10 mg/L), measuring peak areas by using a High Performance Liquid Chromatograph (HPLC) and drawing a standard curve, wherein a mobile phase is acetonitrile: water =85:15, sample size 10. Mu.L, run time 8 minutes. And (3) determining the apparent solubility of benzo [ a ] pyrene in the sample to be detected.
The sample soil is collected from great Xingjiang school campus of Beijing building university, is placed in a laboratory drying and ventilating place, after the original soil is completely dried, large-volume impurities such as gravel, leaves, roots and the like in the original soil are removed, then the soil is ground and sieved by a sieve with the aperture of 0.5mm, and soil particles with the particle size of less than 0.5mm are taken and sterilized at high temperature for later use.
Measuring a certain amount of benzo [ a ] pyrene, completely dissolving the benzo [ a ] pyrene in a proper amount of acetone, uniformly mixing the solution and the standby soil, then placing the mixture at room temperature for drying until the acetone is completely volatilized, obtaining polluted soil with benzo [ a ] pyrene content of about 20mg/kg, sealing the polluted soil with a wide-mouth bottle, and storing the polluted soil at low temperature.
A built surfactant (MES: APG = 7) elution solution at a concentration of 6g/L was prepared, and the elution process was simulated by a shake flask experiment. Adding 30mL of compound surfactants with different concentrations into a 50mL centrifuge tube filled with 3g of simulated contaminated soil, and keeping the water-soil ratio at 10mL:1g of the total weight of the composition. The slurry mixed in a 50mL glass centrifuge tube was shaken at a rate of 160r/min at a temperature of 20 ℃ for 48h. And centrifuging the soil dispersion liquid after shaking for 48 hours at the rotating speed of 4000r/min for 15min, standing for 30min, and filtering the supernatant by using a 0.22-micron organic microporous filter membrane. And (4) liquid phase testing.
Example 2.2 method for repairing polycyclic aromatic hydrocarbon contaminated soil by surfactant cycle synergism:
a leaching pipeline and a spraying device are arranged above the Polycyclic Aromatic Hydrocarbon (PAHs) polluted soil, and then an extraction well is arranged at the periphery of the polluted soil. Adding the prepared 6g/L compound eluting agent into the eluting pipeline through a pressurizing pump, and leading the compound eluting agent to enter the polluted soil through a spraying device.
The leaching time is about 48h, and the water-soil ratio is 10mL:1g, after the leaching is finished, the washing liquid of the leached soil is extracted and collected by a vacuum suction pump.
Adding biological agents (bacillus subtilis and pseudomonas aeruginosa) into the soil, uniformly mixing the leached soil and the agents in a turning mode, maintaining for 10 days, further repairing the eluted soil, and removing the residual PAHs in the soil and the added MES eluting agent.
Adding 2mmol/L Persulfate (PS) and 2000mg/L biochar into the leacheate, stirring for about 2h, and degrading Polycyclic Aromatic Hydrocarbons (PAHs) in the leacheate.
And (3) measuring the content of Polycyclic Aromatic Hydrocarbons (PAHs) in the degraded eluent by liquid phase measurement, completely degrading the Polycyclic Aromatic Hydrocarbons (PAHs), continuously spraying the eluent into the polluted soil, and circularly eluting the Polycyclic Aromatic Hydrocarbons (PAHs).
In the surfactant synergistic bioadsorption process, the easily biodegradable green surfactant has more advantages in order to avoid secondary pollution and ensure soil bioavailability.
The method for synergistic remediation of polycyclic aromatic hydrocarbon-contaminated soil in the above embodiment can be applied to the elution degradation device for synergistic remediation of polycyclic aromatic hydrocarbon-contaminated soil in embodiment 3.
Example 3. Device for synergistic remediation of polycyclic aromatic hydrocarbon contaminated soil with surfactant recycling, as shown in figure 3, comprises: the impeller 1 is connected with a motor 3, the central shaft of the impeller 1 is also connected with a clutch 2, and the impeller 1 is driven by the motor 3; a peristaltic pump tube 4 is arranged above the impeller 1, and the peristaltic pump tube 4 is connected with a degradation device 6; the degradation device 6 is internally provided with a sponge 7 which is impregnated with biochar and is used for degrading pollutants in the eluent.
The peristaltic pump pipe 4 is provided with a peristaltic pump 5 for facilitating extraction of the reacted eluent, the eluent is degraded by a degradation device 6 and a biochar-impregnated sponge 7, and the discharged and purified eluent is conveyed to soil through a pipeline again for repeated desorption and purification.
When the elution degradation device for restoring the polycyclic aromatic hydrocarbon polluted soil in an synergistic manner is adopted, firstly, the impeller 1 is used for fully stirring the surfactant and the soil for 48 hours, then, the clutch 2 is used for centrifugation, the soil eluent is separated from the soil, the eluent is lifted to the degradation device 6 by the peristaltic pump and passes through the biochar-impregnated sponge 7 arranged in the degradation device 6 from top to bottom, the polycyclic aromatic hydrocarbon in the eluent is degraded, and the degraded water sample circulates to continuously elute the polluted soil.
The soil remediation method of the embodiment has the positive effects that:
(1) Can effectively restore polycyclic aromatic hydrocarbon in soil and provide a new raw material for the eluent in the soil restoration technology.
(2) As a natural raw material, the cost is low. And the raw materials have good renewability, environmental compatibility and biodegradability at the same time.
(3) The irritation and toxicity to human body are lower than those of linear alkylbenzene sulfonate LAS, and the product is non-toxic to aquatic organisms.
(4) Has good hard water resistance and good calcium soap dispersibility.
(5) The polluted soil can be circularly eluted, and the cost is saved.
As can be seen from figure 1, the removal rate of the compound surfactant to benzo [ a ] pyrene in soil increases with the increase of the concentration, and compared with the washing effect of the benzo [ a ] pyrene when the concentration of the surfactant is 6g/L, the washing effect is the best, and can reach 63.74%.
As can be seen from FIG. 2, with the increase of the added amount of the biochar, the adsorption and degradation effects on benzo [ a ] pyrene in the eluent are also increased, and when the added amount of the biochar is 3000mg/L, the degradation rate can reach 99.4%, and the degradation rate is lower than a preset threshold value, so that the eluent can be recycled to further elute the contaminated soil.
Claims (9)
1. The method for repairing the polycyclic aromatic hydrocarbon polluted soil by the circulating synergistic effect of the surfactant is characterized by comprising the following steps:
s1, spraying a compounded surfactant into the polluted soil for not less than 48 hours, and collecting a washing liquid which is remained after the surfactant reacts with the pollutants in the soil after the spraying is finished;
s2, adding a biological agent into the soil after the washing liquid is collected, uniformly mixing the biological agent with the soil, and maintaining for at least 10 days to obtain repaired soil;
s3, detecting whether the repaired soil meets a repair standard, and if not, circularly executing the step S1 and the step S2 until the repaired soil meets the repair standard; if the soil does not continue to be repaired when the soil meets the repair standard, executing the step S4;
s4, adding 0.5-2 mmol/L persulfate and biochar with a preset concentration into the residual washing liquid, and stirring for not less than 2 hours to degrade the polycyclic aromatic hydrocarbon in the washing liquid;
and S5, spraying the washing liquid to the polluted soil in the step S1 again to perform secondary solubilization desorption for soil remediation in the step S2 or spraying the washing liquid to the next batch of polluted soil for circularly eluting the polycyclic aromatic hydrocarbon in the polluted soil.
2. The method for recycling and enhancing the remediation of polycyclic aromatic hydrocarbon contaminated soil according to claim 1, wherein the concentration of the active ingredient contained in the surfactant formulated in the step S1 is 1 to 6g/L.
3. The method for recycling and enhancing the remediation of polycyclic aromatic hydrocarbon contaminated soil according to claim 1, wherein the volume to soil ratio of the formulated surfactant in step S1 is 5mL:1 g-30 mL:1g.
4. The method for recycling and enhancing remediation of polycyclic aromatic hydrocarbon contaminated soil according to claim 1, wherein the biological agent in step S3 is bacillus subtilis or pseudomonas aeruginosa.
5. The method for cyclic synergistic remediation of polycyclic aromatic hydrocarbon contaminated soil according to any one of claims 1 to 4, wherein the volume concentration of biochar added in step S4 is from 0.1g/L to 3g/L.
6. The method for cyclic synergistic remediation of polycyclic aromatic hydrocarbon contaminated soil according to any one of claims 1 to 4, wherein the compounded surfactant is a surfactant having a volume ratio of 7:1 sodium fatty acid methyl ester sulfonate and alkyl glycoside.
7. The method for recycling and enhancing the soil polluted by polycyclic aromatic hydrocarbon according to claim 6, wherein the polycyclic aromatic hydrocarbon is benzo [ a ] pyrene, phenanthrene, naphthalene.
8. The elution degradation device of polycyclic aromatic hydrocarbon contaminated soil is restoreed in surfactant circulation increase, its characterized in that includes: the impeller (1), the impeller (1) is connected with a motor (3), the central shaft of the impeller (1) is also connected with a clutch (2), and the impeller (1) is driven by the motor (3); a peristaltic pump tube (4) is arranged above the impeller (1), and the peristaltic pump tube (4) is connected with a degradation device (6); a biochar impregnated sponge (7) is arranged in the degradation device (6) which degrades contaminants in the washing liquid by a method according to any of claims 1-7.
9. The elution and degradation device for recycling, synergizing and remediating polycyclic aromatic hydrocarbon contaminated soil according to claim 8, wherein the peristaltic pump (5) is arranged on the peristaltic pump tube (4) and is used for extracting a washing solution after reaction, the washing solution is degraded by the degradation device (6) and a sponge (7) impregnated with charcoal therein, and the purified washing solution is discharged and conveyed to the soil again through a pipeline for repeated desorption and purification.
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| CN117798181A (en) * | 2023-12-01 | 2024-04-02 | 同济大学 | Method for activating and degrading high-concentration polycyclic aromatic hydrocarbon in soil by alkali and surfactant |
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| CN117798181A (en) * | 2023-12-01 | 2024-04-02 | 同济大学 | Method for activating and degrading high-concentration polycyclic aromatic hydrocarbon in soil by alkali and surfactant |
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