Pretreatment extraction method of petroleum hydrocarbon in soil

Abstract

The invention discloses a pretreatment extraction method of petroleum hydrocarbon in soil, which comprises the following steps: S1, weighing a certain amount of soil sample, putting the soil sample into a glass bottle with a bottle cap, then adding a compound extracting agent into the glass bottle, and then dropwise adding a demulsifier; s2, adding an extraction solvent into the glass bottle, and tightening a bottle cap; s3, fully mixing the solid phase and the liquid phase in the glass bottle, standing for layering, and collecting an organic phase; and S4, purifying the organic phase obtained in the step S3 by using a purification column to finally obtain a sample solution. The method is easy to operate, low in treatment cost, high in extraction efficiency, basically harmless to experimenters and the environment, capable of efficiently obtaining petroleum hydrocarbon content data close to the reality in the soil, free of special requirements for equipment, capable of achieving large-scale continuous production and worthy of application and popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of soil environmental governance, and in particular relates to a pretreatment extraction method for petroleum hydrocarbons in soil. Background Art

[0002] With the rapid development of my country's social economy, the expansion of industrial and agricultural scale and the continuous growth of consumer demand, my country's demand for crude oil and petroleum products is extremely huge. The large-scale use of petroleum products and the rapid development of the petroleum industry will inevitably lead to a large number of petroleum pollution problems, especially the occurrence of petroleum pollution in the soil. According to statistics, during the production, transportation, storage and sales of petroleum and its products, blowout accidents, leakage and sedimentation irrigation discharge may cause soil petroleum pollution to varying degrees, and the land contaminated by petroleum has exceeded more than 5 million hectares.

[0003] In petroleum-contaminated soil, petroleum hydrocarbons are the main pollutants. Once they enter the soil, they will destroy the soil structure, reduce soil permeability, affect soil utilization value, and even migrate downward to pollute groundwater. In addition, petroleum hydrocarbons are highly toxic, persistent in the environment, difficult to degrade, and easy to migrate. They can accumulate in plants and enrich to the human body through the food chain. In particular, the polycyclic aromatic hydrocarbons they contain have teratogenic, carcinogenic, and mutagenic effects, which seriously threaten human health. People should attach great importance to petroleum hydrocarbon pollution in the soil, discover it in time, and take corresponding measures.

[0004] Therefore, it is necessary to detect petroleum hydrocarbons in soil, and the extraction method of the target is an important part of the detection process, which affects the accuracy and reliability of the measurement results. However, the current extraction of petroleum hydrocarbons in soil mainly involves Soxhlet extraction, accelerated solvent extraction, ultrasonic extraction, oscillation extraction, microwave extraction, etc. The above methods all use organic solvents to directly contact soil samples to extract petroleum hydrocarbons, which cannot solve the adsorption problem caused by the strong affinity between petroleum hydrocarbons and soil, resulting in low extraction efficiency. The accuracy and reliability of the petroleum hydrocarbon content in the soil need to be improved; in addition, the instruments and equipment required for the above methods are complex and expensive, the amount of organic reagents used is large, and the requirements for operators are high. Such extraction methods not only have low sample processing efficiency, but also high costs, which greatly wastes laboratory resources. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for pre-treatment and extraction of petroleum hydrocarbons in soil which is efficient, rapid, simple and practical.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solution: a pretreatment extraction method of petroleum hydrocarbons in soil, comprising the following steps:

[0007] S1. Weigh a certain amount of soil sample and put it into a glass bottle with a cap, then add the compound extractant into the glass bottle, and then dropwise add the demulsifier;

[0008] S2, add the extraction solvent into the glass bottle and tighten the bottle cap;

[0009] S3, fully mix the solid and liquid phases in the glass bottle, let stand and separate, and collect the organic phase;

[0010] S4. Purify the organic phase obtained in step S3 using a purification column to obtain a sample solution.

[0011] Furthermore, the petroleum hydrocarbons are extractable total petroleum hydrocarbons C 10 -C 40 ;

[0012] The specific preparation process of soil samples is as follows: a certain amount of soil is dried at 105°C for 24 h to remove interfering substances; a certain amount of soil with a concentration of 31000 mg·L is taken after passing through a 100-mesh sieve. -1 The petroleum hydrocarbon standard solution was diluted to 200 mL using n-hexane solvent, and then mixed evenly with 500 g of sieved soil. The solvent was evaporated under ventilation conditions to obtain soil samples containing petroleum hydrocarbons; corresponding amounts of deionized water were added to the soil samples to obtain soil samples with different water contents.

[0013] Furthermore, a silicone gasket is provided in the bottle cap described in step S1, and a polytetrafluoroethylene film is coated on the contact surface of the silicone gasket with the solution.

[0014] Furthermore, the compound extractant described in step S1 adopts a mixed solution of anionic surfactants sodium dodecylbenzene sulfonate, Tween 80 and Na2SiO3, the concentration of sodium dodecylbenzene sulfonate is 2.0 g / L, the concentration of Tween 80 is 0.2 g / L, the concentration of Na2SiO3 is 5.0 g / L, and the ratio of soil sample to compound extractant is 1:2-4 g / mL.

[0015] Furthermore, the demulsifier described in step S1 is a H2SO4 solution, the volume ratio of sulfuric acid to water in the H2SO4 solution is equal, and the amount of the demulsifier added is 1 to 5 drops.

[0016] Furthermore, the extraction solvent described in step S2 is a non-polar solvent, which includes but is not limited to n-pentane, n-hexane, n-heptane, cyclohexane or cycloheptane, and is used according to the requirements of the subsequent detection method.

[0017] Furthermore, in step S2, the volume of the added extraction solvent is determined according to the volume of the compound extraction agent, and the volume ratio of the compound extraction agent to the extraction solvent is 5:1 to 2:1.

[0018] Furthermore, the methods for sufficient mixing in step S3 include but are not limited to magnetic stirring, tumbling oscillation, ultrasound and / or heating.

[0019] Furthermore, the purification column described in step S4 is a purification device filled with a magnesium silicate type adsorbent.

[0020] Furthermore, the specific process of separation and purification described in step S4 is: after removing water and concentrating the obtained organic phase to 2-5 mL, all of it is transferred to the purification column, and the loading solution purified by the purification column is collected to obtain the sample solution.

[0021] By adopting the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0022] First: The present invention significantly reduces the interfacial tension of the physical phases by adding a compound surfactant, thereby promoting the desorption of petroleum hydrocarbons adsorbed by the soil, reducing the oil-water phase opposition, increasing its solubility in the water phase, solving the problem of the strong affinity between petroleum hydrocarbons and soil, and improving the extraction efficiency. This method can efficiently obtain data on the petroleum hydrocarbon content in the soil that is close to the actual value.

[0023] Second: The organic solvent consumption of the present invention is about 20% to 40% of that of the existing pretreatment method, which reduces the amount of solvent used and can greatly save sample processing costs. At the same time, it avoids the use of highly toxic solvents and reduces the harm to experimenters and the environment.

[0024] Third: The method of the present invention is simple to operate, saves 60% to 80% of the sample processing time, reduces the volatilization loss of the target object, and at the same time, reduces the workload of on-site experimental personnel and improves work efficiency; the value of the instruments and consumables used is less than 5% of the existing pre-treatment methods, there are no special requirements for the equipment, and large-scale continuous production can be carried out, which is worthy of promotion.

[0025] Fourth: The extraction method of the present invention has good reproducibility and high extraction efficiency. Through experiments, the recovery rate is between 78.5% and 115.8%. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are further described in detail below in conjunction with the attached tables and examples.

[0027] Example 1

[0028] This embodiment provides a kind of petroleum hydrocarbon (C 10 -C 40 ) pre-treatment extraction method, specifically comprising the following steps:

[0029] S1. Weigh 10.0 g of soil sample prepared from Henan tidal soil and put it into a glass bottle with a cap. Add 20 mL of compound extractant into the glass bottle and add 1 drop of demulsifier.

[0030] S2. Add 10 mL of n-hexane into the glass bottle and tighten the cap;

[0031] S3, oscillate at room temperature for 15 minutes, let stand for 10 minutes, and collect the upper extract;

[0032] S4, repeat the above steps S2 and S3 to combine the extracts;

[0033] S5. Dehydrate the extract with anhydrous sodium sulfate and transfer it to a magnesium silicate solid phase extraction column for purification. Collect the eluate to obtain a sample solution.

[0034] Example 2

[0035] A kind of petroleum hydrocarbon (C 10 -C 40 ) is a pretreatment extraction method according to Example 1, which differs from that in Example 1 in that, in step S3, magnetic stirring is performed at room temperature for 15 min, and after standing for 10 min, the upper extract is collected.

[0036] Example 3

[0037] A kind of petroleum hydrocarbon (C 10 -C 40 ) is different from the extraction method of Example 1 in that, in step S3, magnetic stirring is performed for 15 minutes in a water bath at a constant temperature (40° C.), and after standing for 10 minutes, the upper extract is collected.

[0038] Example 4

[0039] A kind of petroleum hydrocarbon (C 10 -C 40 ) is a pretreatment extraction method, which differs from Example 3 in that, in step S1, 15.0 g of a soil sample prepared from Shaanxi loess soil is selected, 30 mL of a composite extractant is added, and 2 drops of a demulsifier are added.

[0040] Example 5

[0041] A kind of petroleum hydrocarbon (C 10 -C 40 ) is a pretreatment extraction method, which is different from that of Example 3 in that, in step S1, 20.0 g of a soil sample prepared from Heilongjiang black soil is selected, 30 mL of a composite extractant is added, and 4 drops of a demulsifier are added.

[0042] Example 6

[0043] A kind of petroleum hydrocarbon (C10 -C 40 ) is a pre-treatment extraction method, which is different from that of Example 3 in that, in step S1, 15.0 g of soil sample prepared from Jiangxi red soil is selected.

[0044] The specific test results of the above six embodiments are shown in Table 1 and Table 2 below.

[0045] Table 1 Effect of different soils on the extraction efficiency of petroleum hydrocarbons (n ​​= 3, representing that each example test was repeated 3 times, and only with repetitions can the RSD in the table be calculated and needs to be retained)

[0046]

[0047] Table 2 Comparison of different pretreatment methods in terms of efficiency, harm and cost

[0048]

[0049] The above embodiments illustrate the basic principles and features of the present invention, but the above only illustrates the preferred embodiments of the present invention and is not limited to the embodiments. Under the inspiration of this patent, a person skilled in the art can make many forms of deformation and improvement without departing from the scope of protection of the present invention and the claims, which are all within the protection scope of the present invention. Therefore, the patent and protection scope of the present invention shall be subject to the attached claims.

Claims

1. A method for pre-treatment and extraction of petroleum hydrocarbons in soil, characterized in that: The following steps are involved: S1. Weigh a certain amount of soil sample and put it into a glass bottle with a cap, then add the compound extractant into the glass bottle, and then dropwise add the demulsifier; S2, add the extraction solvent into the glass bottle and tighten the bottle cap; S3, fully mix the solid and liquid phases in the glass bottle, let stand and separate, and collect the organic phase; S4. Purify the organic phase obtained in step S3 using a purification column to obtain a sample solution.

2. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: The petroleum hydrocarbons are extractable total petroleum hydrocarbons C 10 -C 40 ; The specific preparation process of soil samples is as follows: a certain amount of soil is dried at 105°C for 24 h to remove interfering substances; a certain amount of soil with a concentration of 31000 mg·L is taken after passing through a 100-mesh sieve. -1 Petroleum hydrocarbons (C 10 -C 40 ) standard solution was diluted to 200 mL using n-hexane solvent, and then mixed evenly with 500 g of sieved soil. The solvent was evaporated under ventilation conditions to obtain a soil sample containing petroleum hydrocarbons; corresponding amounts of deionized water were added to the soil sample to obtain soil samples with different water contents.

3. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: The bottle cap described in step S1 is provided with a silicone gasket, and the surface of the silicone gasket in contact with the solution is coated with a layer of polytetrafluoroethylene film.

4. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: The compound extractant described in step S1 adopts a mixed solution of anionic surfactants sodium dodecylbenzene sulfonate, Tween 80 and Na2SiO3, the concentration of sodium dodecylbenzene sulfonate is 2.0 g / L, the concentration of Tween 80 is 0.2 g / L, the concentration of Na2SiO3 is 5.0 g / L, and the ratio of soil sample to compound extractant is 1:2-4 g / mL.

5. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: The demulsifier described in step S1 is a H2SO4 solution, in which the volume ratio of sulfuric acid to water is equal, and the amount of the demulsifier added is 1 to 5 drops.

6. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: The extraction solvent described in step S2 is a non-polar solvent, which includes but is not limited to n-pentane, n-hexane, n-heptane, cyclohexane or cycloheptane, and is used according to the requirements of the subsequent detection method.

7. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: In step S2, the volume of the added extraction solvent is determined according to the volume of the compound extraction agent, and the volume ratio of the compound extraction agent to the extraction solvent is 5:1 to 2:

1.

8. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: The methods of sufficient mixing in step S3 include, but are not limited to, magnetic stirring, tumbling oscillation, ultrasound and / or heating.

9. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: The purification column described in step S4 is a purification device filled with magnesium silicate type adsorbent.

10. The method for pre-treatment and extraction of petroleum hydrocarbons in soil according to claim 1, characterized in that: The specific process of separation and purification described in step S4 is: after removing water and concentrating the obtained organic phase to 2-5 mL, all of it is transferred to the purification column, and the loading solution purified by the purification column is collected to obtain the sample solution.

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