CN112504791B - Method for rapidly extracting polychlorinated biphenyl from soil and sediment - Google Patents

Abstract

The invention relates to the technical field of soil analysis, and discloses a rapid extraction method of polychlorinated biphenyl in soil and sediment. According to the invention, the soil sample pretreatment process is optimized, most of organic matters in the soil are decomposed by microorganisms, microorganisms in the soil are killed by high-temperature treatment, and partial organic matters are destroyed, so that the content of free polychlorinated biphenyl in the soil is increased; when polychlorinated biphenyl is extracted, under the extraction condition of the invention, the time consumed in polychlorinated biphenyl extraction can be reduced, the consumption of extraction solvent can be reduced, and the extraction efficiency and the extraction amount of polychlorinated biphenyl in soil can be improved.

Description

Method for rapidly extracting polychlorinated biphenyl from soil and sediment

Technical Field

The invention relates to the technical field of soil analysis, in particular to a rapid extraction method of polychlorinated biphenyl in soil and sediment.

Background

Soil is a material basis on which humans depend to survive, is an indispensable and non-renewable natural resource for humans, and is also an important component of the human ecological environment. With the rapid development of industrial production in China, village and town enterprises and rural town, the quality of soil environment is increasingly deteriorated, and particularly, the problem of residue of harmful substances in pesticides and wastes is solved. In order to treat and repair soil, the harmful residues in the soil need to be extracted and analyzed, and polychlorinated biphenyls (polychlorinated biphenyls, abbreviated as PCBs) are one of them. Polychlorinated biphenyls (PCBs) are a class of organic contaminants that have characteristics of toxicity, lipophilicity, semi-volatility, and bioaccumulation, including 209 homologs. The hydrophobicity and low water solubility of PCBs make them readily adsorbed in soil, sediment and sludge, and PCBs, once discharged into the environment, persist and become enriched in organisms. The background value of polychlorinated biphenyl in air ranges from 1 to 100 mug/g, and the background value in soil ranges from 100 to 1000 mug/g. The distribution of polychlorinated biphenyls in the environment is fluid and is affected by a variety of factors. Polychlorinated biphenyls in the atmosphere are mainly low-chlorine biphenyls, e.g., PCB11 is present in urban air at a concentration of about 15% of the total PCBs, but only about 0.16% is from electronic products. More than 50 polychlorinated biphenyls are found in azo and phthalocyanine pigments and are present in concentrations as high as 200ng/g. The severity of PCBs contamination is mainly due to the ubiquitous nature of PCBs, which are widely found in soil, atmosphere, water and organisms; PCBs have immunological toxicity, neurotoxicity, teratogenicity, mutagenicity and carcinogenicity, and are extremely harmful to human health.

The extraction method of polychlorinated biphenyl comprises Soxhlet extraction, ultrasonic extraction, supercritical fluid extraction, microwave-assisted extraction, accelerated solvent extraction and the like, and the extraction method or the extraction time is too long, the time is wasted, or the solvent consumption is too large, and the extraction efficiency is low. The inventor provides a rapid extraction method of polychlorinated biphenyl in soil and sediment aiming at the characteristic that PCBs are adsorbed with organic matters in the soil after entering the soil.

Disclosure of Invention

Based on the problems, the invention provides a rapid extraction method of polychlorinated biphenyl in soil and sediment, which optimizes the pretreatment process of soil samples, reduces the time consumed in the later extraction of polychlorinated biphenyl, reduces the consumption of extraction solvent, and improves the extraction efficiency and the extraction quantity.

In order to solve the technical problems, the invention provides a rapid extraction method of polychlorinated biphenyl in soil and sediment, which comprises the following steps:

s1: soil sample pretreatment

Collecting a representative soil sample, air-drying the soil sample, crushing, grinding and sieving; adding sterile water into a soil sample, wherein the addition amount of the sterile water is suitable for stirring the soil into slurry, and then adding a microbial composite bacterial agent for decomposing soil organic matters into the soil sample, wherein the mass ratio of the microbial composite bacterial agent to the soil sample is 1:10, the reaction conditions are as follows: the reaction temperature is 15-30 ℃, reactants are continuously stirred in the reaction process, the initial reaction is aerobic reaction, the aerobic reaction time is 24 hours, then the anaerobic reaction is carried out, and the anaerobic reaction time is 24 hours; then the mixture after the reaction is put into a baking oven for baking, the mixture is continuously stirred in the baking process, and the baking flow is as follows: baking at 100-120 deg.c to dry the mixture, crushing and grinding the mixture, and treating at 200 deg.c for 2-3 min to cool the mixture to room temperature;

s2: extraction of polychlorinated biphenyl

Adding a normal hexane/acetone solution into the mixture treated in the step S1, wherein the ratio of the normal hexane/acetone solution to the mixture is as follows: 1ml of n-hexane/acetone solution 1g of mixture, extraction conditions were as follows: the extraction temperature is 80 ℃, the extraction pressure is 10MPa, the extraction microwave radiation power is 1000W, and the extraction time is 3-6min; centrifuging at 8000r/min for 4min, collecting supernatant, centrifuging at 8000r/min for 4min, and collecting supernatant.

Further, the microbial composite bacterial agent for decomposing soil organic matters in the step S1 comprises carbohydrate decomposing microorganisms, carbon-containing organic matters decomposing microorganisms and phosphorus-containing sulfur organic matters decomposing microorganisms, wherein the mass ratio of the carbohydrate decomposing microorganisms to the carbon-containing organic matters decomposing microorganisms to the phosphorus-containing sulfur organic matters decomposing microorganisms is 1:1:1.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the soil sample pretreatment process is optimized, most of organic matters in the soil are decomposed by microorganisms, microorganisms in the soil are killed by high-temperature treatment, and partial organic matters are destroyed, so that the content of free polychlorinated biphenyl in the soil is increased; when polychlorinated biphenyl is extracted, under the extraction condition of the invention, the time consumed in polychlorinated biphenyl extraction can be reduced, the consumption of extraction solvent can be reduced, and the extraction efficiency and the extraction amount of polychlorinated biphenyl in soil can be improved.

Detailed Description

The present invention will be described in further detail with reference to the following examples, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent, and the description thereof is merely illustrative of the present invention and not intended to be limiting.

Examples:

the embodiment provides a rapid extraction method of polychlorinated biphenyl in soil and sediment, which comprises the following steps:

s1: soil sample pretreatment

Collecting a representative soil sample, air-drying the soil sample, crushing, grinding and sieving; adding sterile water into a soil sample, wherein the addition amount of the sterile water is suitable for stirring the soil into slurry, and then adding a microbial composite microbial agent for decomposing soil organic matters into the soil sample, wherein the microbial composite microbial agent for decomposing the soil organic matters comprises carbohydrate decomposing microorganisms, carbon-containing organic matters decomposing microorganisms and phosphorus-containing sulfur organic matters decomposing microorganisms, and the mass ratio of the carbohydrate decomposing microorganisms to the carbon-containing organic matters decomposing microorganisms to the phosphorus-containing sulfur organic matters decomposing microorganisms is 1:1:1; the mass ratio of the microbial composite bacterial agent to the soil sample is 1:10, decomposing organic matters by utilizing a microorganism composite microbial agent to desorb polychlorinated biphenyl adsorbed on the organic matters, wherein the reaction conditions are as follows: the reaction temperature is 15-30 ℃, reactants are continuously stirred in the reaction process, the initial reaction is aerobic reaction, the aerobic reaction time is 24 hours, then the anaerobic reaction is carried out, the anaerobic reaction and the aerobic reaction are continuously carried out, and the anaerobic decomposition and the aerobic decomposition of soil organic matters are satisfied; then the mixture after the reaction is put into a baking oven for baking, the mixture is continuously stirred in the baking process, and the baking flow is as follows: baking at 100-120 deg.c to dry the mixture, crushing and grinding the mixture, and treating at 200 deg.c for 2-3 min to cool the mixture to room temperature; in the drying process, the microorganism is killed and decomposed, and polychlorinated biphenyl adsorbed on the microorganism is desorbed;

s2: extraction of polychlorinated biphenyl

Adding a normal hexane/acetone solution into the mixture treated in the step S1, wherein the ratio of the normal hexane/acetone solution to the mixture is as follows: 1ml of n-hexane/acetone solution 1g of mixture, extraction conditions were as follows: the extraction temperature is 80 ℃, the extraction pressure is 10MPa, the extraction microwave radiation power is 1000W, and the extraction time is 3-6min; centrifuging at 8000r/min for 4min, collecting supernatant, centrifuging at 8000r/min for 4min, and collecting supernatant.

In this example, the extraction method of this example was compared with the usual accelerated solvent extraction method and ultrasonic extraction method, and the comparison experiment was as follows: three identical soil samples were taken, and the extraction method of this example, the conventional accelerated solvent extraction method and the ultrasonic extraction method were used to extract the trichlorobiphenyl in the soil, and the recovery rates of the trichlorobiphenyl extracted by the above three methods were measured by GC-MS method, respectively, and the results are shown in table 1.

TABLE 1 recovery rates of three extraction methods (%)

PCB	This embodiment	Accelerated solvent extraction	Ultrasonic extraction
				PCB5	74	72.3	70
PCB99	94.6	94	92.6
				PCB128	91.4	92	88.9
PCB4	86	83	80
				PCB77	90.1	88	87.6
PCB87	95.5	95.7	94.2

As can be seen from table 1, the recovery rate of the present example was higher for all six PCBs than for the ultrasonic extraction, and the recovery rate of the present example was higher for most of the six PCBs than for the accelerated solvent extraction. The method of this example showed higher recovery rate and higher extraction efficiency, and the ultrasonic extraction method used more solvent than the accelerated solvent extraction method, which used 1.5ml/g soil sample, and the method of this example used 1ml/g soil sample, and the method of this example used less solvent than the accelerated solvent extraction method.

The above is an embodiment of the present invention. The foregoing embodiments and the specific parameters of the embodiments are only for clarity of description of the invention and are not intended to limit the scope of the invention, which is defined by the appended claims, and all equivalent structural changes made in the content of the description of the invention are intended to be included in the scope of the invention.

Claims (1)

1. A rapid extraction method of polychlorinated biphenyl in soil and sediment is characterized by comprising the following steps:

s1: soil sample pretreatment

Collecting a representative soil sample, air-drying the soil sample, crushing, grinding and sieving; adding sterile water into the soil sample, wherein the addition amount of the sterile water is suitable for stirring the soil sample into slurry, and then adding a microbial composite bacterial agent for decomposing organic matters of the soil sample into the soil sample, wherein the mass ratio of the microbial composite bacterial agent to the soil sample is 1:10; the following reactions were carried out: the reaction temperature is 15-30 ℃, reactants are continuously stirred in the reaction process, the initial reaction is aerobic reaction, the aerobic reaction time is 24 hours, then the anaerobic reaction is carried out, and the anaerobic reaction time is 24 hours; then the mixture after the reaction is put into a baking oven for baking, the mixture is continuously stirred in the baking process, and the baking flow is as follows: firstly, baking at the temperature of 100-120 ℃ until the mixture is completely dried, crushing and grinding the mixture, then rapidly raising the temperature to 200 ℃ for 2-3 min, and naturally cooling the mixture to room temperature for later use; the microbial composite microbial agent comprises carbohydrate decomposing microorganisms, carbon-containing organic matter decomposing microorganisms and phosphorus-containing sulfur organic matter decomposing microorganisms, wherein the mass ratio of the carbohydrate decomposing microorganisms to the carbon-containing organic matter decomposing microorganisms to the phosphorus-containing sulfur organic matter decomposing microorganisms is 1:1:1;

s2: extraction of polychlorinated biphenyl

Adding a normal hexane/acetone solution into the mixture treated in the step S1, wherein the ratio of the normal hexane/acetone solution to the mixture is as follows: 1ml of n-hexane/acetone solution 1g of mixture, extraction conditions were as follows: the extraction temperature is 80 ℃, the extraction pressure is 10MPa, the extraction microwave radiation power is 1000W, and the extraction time is 3-6min; centrifuging at 8000r/min for 4min, collecting supernatant, centrifuging at 8000r/min for 4min, and collecting supernatant.