CN110961440B - Application of soil extractant in treating lead-polluted soil - Google Patents
Application of soil extractant in treating lead-polluted soil Download PDFInfo
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- CN110961440B CN110961440B CN201811150937.1A CN201811150937A CN110961440B CN 110961440 B CN110961440 B CN 110961440B CN 201811150937 A CN201811150937 A CN 201811150937A CN 110961440 B CN110961440 B CN 110961440B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
Abstract
The invention discloses an application of a soil extractant in treating lead-polluted soil, wherein the soil extractant is prepared from raw materialsThe material carbon and the magnetic powder are compounded. Wherein the biomass charcoal and magnetic powder (Fe)3O4) The mass ratio of (1.5-2.5): 1. when the adding mass of the soil extractant in the soil is 5%, the lead pollution concentration is reduced by 30.8-41.9% after the soil extractant treats lead-polluted soil for 7 days. In the technical scheme, when the adding mass of the soil extractant in the soil is 5%, the lead pollution concentration is reduced by 26.8-40.1% after the soil extractant treats lead-polluted soil for 30 days.
Description
Technical Field
The invention relates to the technical field of environmental protection, in particular to application of a soil extractant in treating lead-polluted soil.
Background
The soil is one of the main natural resources on which human beings rely to live and is also an important component of the ecological environment, and because the waste water and waste residues generated by the increasing industrial and agricultural production scale are increased continuously, the waste not only destroys the vegetation on the earth surface, but also toxic and harmful heavy metals in the waste water can enter the surrounding soil environment along with the discharge of the waste water, the weathering and leaching of waste residue piles to influence the growth of the earth surface organisms, and can enter human bodies and other animal bodies through food chains to be enriched so as to influence the health of the human bodies.
The heavy metal enrichment in the farmland reaches a certain degree, so that the yield and the quality of crops are reduced, and the safety of an ecological system and human beings is seriously threatened. However, the heavy metal contaminated soil remediation work just starts in China, and the remediation rate is less than 3 percent at present. Lead is one of important heavy metal elements for pollution, and is also a non-essential element for human beings, animals and plants. The research on lead pollution of soil has been more and more concerned by scholars at home and abroad. With the increasing quantity of urban waste utilized in agriculture, the trend of heavy metal pollution in farmlands is increasingly obvious, and the lead pollution condition is increasingly serious. Lead pollution can cause the growth of crops to be hindered, the yield is greatly reduced, and the quality is reduced. Therefore, in China, the task of preventing and controlling heavy metal pollution of soil is facing more and more serious examination, and the research and development of corresponding treatment technologies become tasks which need to be solved urgently by environmental workers.
For the research of soil remediation polluted by heavy metals, two strategies are mainly used at present: one is immobilization, which fixes heavy metals in the soil and limits their release, thereby reducing their risk. The remediation of the heavy metal contaminated soil refers to the reduction of the mobility and the biological effectiveness of the heavy metal in the soil by removing the heavy metal in the soil out of the soil body or fixing the heavy metal in the soil by using physical, chemical and biological methods, and the reduction of the health risk and the environmental risk of the heavy metal. This is also the method of the existing technology to reduce mainly heavy metal contamination. For example, the soil heavy metal adsorbent applied to plum-blossom in 2017 is the invention patent, and the soil heavy metal stabilizing agent applied to Zhao attacking City in 2018 is the invention patent. However, the passivated heavy metal still remains in the soil, so that the risk of secondary precipitation exists, and the pollution treatment of the heavy metal is not thorough. Secondly, removing heavy metals from the soil to achieve the aim of cleaning the soil; at present, super-accumulation plants are often adopted to extract heavy metals in soil, for example, a remediation method for heavy metal pollution of soil applied by Wangxinluo in 2017 is to use ragweed to carry out super-accumulation extraction on the heavy metals, and finally, the ragweed is burnt, and the problems that the extraction capacity is insufficient, secondary pollution is formed in subsequent treatment and the like exist when heavy metal adsorption treatment is carried out by using organisms.
The biomass charcoal is a carbonaceous material with smaller particle size and larger pore diameter, which is prepared by thermally cracking biomass with rich carbon content under the condition of no oxygen or limited oxygen. It has the advantages of wide and easily available raw materials, simple and convenient preparation process, low cost and the like. In recent years, biomass charcoal has attracted extensive attention as a new type of environmental functional material, and has shown great application potential in soil improvement, and has become a research hotspot in the current environmental science field. The biomass carbon has strong adsorption capacity on heavy metal ions, and can effectively reduce the content and effectiveness of heavy metals in soil. At present, the potential application value of biomass charcoal in treating heavy metal pollution is widely accepted by academia, and the biomass charcoal has very wide prospects in the aspects of improving the stability of heavy metal, controlling pollution, repairing soil and the like.
Disclosure of Invention
The invention aims to provide the application of a soil extracting agent in treating lead-polluted soil, aiming at the technical defects in the prior art.
The technical scheme adopted for realizing the purpose of the invention is as follows:
the application of a soil extractant in treating lead-polluted soil is characterized in that the soil extractant is prepared by the following method:
step 1, preparing biomass carbon: after washing, air-drying and crushing, under the condition of an initial temperature of 25 ℃, heating to 250-350 ℃ with lower limit oxygen under the heating condition of 10-30 ℃/min, keeping high-temperature pyrolysis for 3-5 hours, then hermetically cooling to 25-30 ℃, removing surface ash, and sieving with a 80-mesh sieve for later use;
step 2, compounding: dissolving 2.5-3 parts by mass of ferric chloride hexahydrate in deionized water, dissolving 1-1.1 parts by mass of ferrous chloride tetrahydrate in deionized water, mixing 2 iron-containing systems, adding 2-2.5 parts by mass of the biomass carbon obtained in the step 1, uniformly dispersing to obtain a mixed solution, adjusting the pH of the mixed solution to 10-11, mixing for 50-60 minutes, storing at room temperature for 20-30 hours, filtering, washing with deionized water and ethanol, filtering, and drying at 40-50 ℃ to obtain the soil extractant.
In the above technical solution, the dispersion conditions in step 2 are as follows: dispersing at room temperature of 20-30 deg.C under shaking at 70-90rpm for 30-40 min.
In the technical scheme, the pH value is adjusted to 10-11 by using 10M NaOH solution in the step 2.
In the technical scheme, the soil extractant is formed by compounding biomass charcoal and magnetic powder, wherein the mass ratio of the biomass charcoal to the magnetic powder is (2-2.5): 1, wherein the mass of the magnetic powder is Fe3O4The mass meter of (1).
In the technical scheme, when the adding mass of the soil extractant in the soil is 5%, the lead pollution concentration is reduced by 30.8-41.9% after the soil extractant treats lead-polluted soil for 7 days.
In the technical scheme, when the adding mass of the soil extractant in the soil is 5%, the lead pollution concentration is reduced by 26.8-40.1% after the soil extractant treats lead-polluted soil for 30 days.
In the technical scheme, the recovery rate of the soil extractant is 94-97% after the soil extractant treats lead-contaminated soil for 7 days.
Compared with the prior art, the invention has the beneficial effects that:
1. the materials used by the composite soil extractant are all environment-friendly materials, so that the secondary pollution to the environment can not be caused, and the cost is lower.
2. The biomass charcoal raw material biomass is cheap and easy to obtain, the preparation operation flow is simple and convenient, and the obtained biomass charcoal material has good adsorption performance and can be produced in batches.
3. The magnetic components and the biomass charcoal in the composite soil extractant are mutually supported and promoted, so that the maximum exertion of the effects of various components is ensured.
4. The combined use and the optimal proportion of the magnetic powder and the biomass charcoal solve the problems that the biomass charcoal added alone cannot be recycled and reused and cannot realize the extraction of lead pollution in soil, enhance the effect of the biomass charcoal and reduce the use cost.
5. The addition of the soil extractant is an economic, convenient, quick and effective means, and can not cause foreign microorganisms, thereby not causing the damage of the foreign microorganisms to the ecological system of the body.
6. The recovery rate is relatively stable, and the recovery rate can reach 95.66% in 7 days.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
Preparing a soil extractant:
the soil extractant is formed by compounding biomass charcoal and magnetic powder. Wherein the biomass charcoal and magnetic powder (Fe)3O4) The mass ratio of (A) to (B) is 2: 1
The preparation method comprises the following steps:
step 1, preparing biomass carbon, washing, air-drying and crushing peeled wheat straws, and then heating to 300 ℃ in an oxygen-limited manner at an initial temperature of 25 ℃ and a temperature rise of 20 ℃/min. And after maintaining high-temperature pyrolysis for 4 hours, sealing and cooling to 25 ℃, removing surface ash, and sieving by a 80-mesh sieve for later use.
Step 2, the compounding process is as follows: 2-2.5 parts by mass of biomass charcoal passes through a 80-mesh sieve, the biomass charcoal is placed into a 1L beaker, 2.5-3 parts by mass of ferric chloride hexahydrate is dissolved in 150ml of deionized water, 1-1.1 parts by mass of ferrous chloride tetrahydrate is dissolved in 50ml of deionized water, and 2 iron-containing systems are mixed and then mixed with a biomass charcoal system for slow oscillation at room temperature for 30 min. The pH is adjusted to 10-11 by using 10M NaOH solution. And (3) mixing for 60 minutes, storing for 24 hours at room temperature, filtering, washing by using deionized water and ethanol until a washing liquid is colorless, clear and transparent, and drying in an oven at 50 ℃ after suction filtration to obtain the soil extractant.
In the technical scheme, the yield of the soil extractant is about 1g of biomass charcoal to prepare 1.5g of the soil extractant.
Example 2
In this embodiment, the soil extractant obtained in example 1 is used for treating the soil pollution in the south of the river, the soil taking point is in the economic source, the range is about 4 mu, soil is taken at multiple points, wheat straw and wheat stubble which are not rotten on the ground are removed during soil taking, and the surface soil is taken to be about 20cm deep. The TOC content was 0.97%. pH 6.36. The original water content was 4.77%, and the saturated water content was 30.16%. The adding amount of the soil extractant is 5 percent (mass ratio), the specific test method is to select 5g of soil sample to mix with 0.25g of magnetic biomass charcoal (0.3725g) prepared by biomass charcoal to test in a 50ml centrifuge tube, add 35ml of deionized water, use, cover tightly and place on a shaking table to oscillate at the rotating speed of 110 rpm. Samples were taken after 7 and 30 days for testing.
The background concentration and post-remediation concentration of lead heavy metals and removal rate are shown in table 2. Wherein: the total amount of lead in soil is digested by a three-acid method, the content of lead in different forms in soil is extracted by a tessier method, and the specific method is disclosed in reference documents: lanzhongrong, Lijia, Dudongyun, Hendcapone, Chengxing, Luying, Xuwenqiang, physical and chemical properties of manganese slag in the composting process and analysis of heavy metal behavior based on the Tessier method [ J ]. environmental engineering report, 2017,11(10): 5637-.
Table 2 the unit of the effect of the soil extractant on lead extraction from the south china soil: mg/kg
The soil extractant has magnetism and can be recovered, and the specific recovery mode is that the soil conditioner in a soil-water mixed system is subjected to magnetic attraction recovery by using a magnet and a magnetic rod, then the recovered soil conditioner is washed, and the recovery rate is determined after drying at 50 ℃. The recovery rate can reach 95.66% in 7 days.
Example 3
The soil extraction agent obtained in the example 1 is used for treating soil sample pollution in Hunan province, soil taking points are located in a certain county in Hunan province, soil is taken at multiple points, wheat straw and wheat stubble which are not rotten on the ground are removed during soil taking, and the surface soil is taken to be about 20cm deep. pH 5.49. The background concentration and post-remediation concentration of lead heavy metals and removal rate are shown in table 3. The original water content is 10.03 percent, and the saturated water content is 38.45 percent.
Table 3 unit of extraction effect of soil extractant on lead in soil of south of hu: mg/kg
From the data, the soil extracting agent can achieve a better effect in 7 days when being used for treating the lead-polluted soil, and is stable in the effect in 30 days. In the practical application process, the extraction of the lead in the soil can be completed after 7 days of application.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (6)
1. The application of the soil extractant in treating lead-polluted soil is characterized in that the soil extractant is prepared by the following method:
step 1, preparing biomass carbon: after washing, air-drying and crushing, under the condition of an initial temperature of 25 ℃, heating to 250-350 ℃ with lower limit oxygen under the heating condition of 10-30 ℃/min, keeping high-temperature pyrolysis for 3-5 hours, then hermetically cooling to 25-30 ℃, removing surface ash, and sieving with a 80-mesh sieve for later use;
step 2, compounding: dissolving 2.5-3 parts by mass of ferric chloride hexahydrate in deionized water, dissolving 1-1.1 parts by mass of ferrous chloride tetrahydrate in deionized water, mixing 2 iron-containing systems, adding 2-2.5 parts by mass of the biomass carbon obtained in the step 1, uniformly dispersing to obtain a mixed solution, adjusting the pH of the mixed solution to 10-11, mixing for 50-60 minutes, storing at room temperature for 20-30 hours, filtering, washing with deionized water and ethanol, filtering, and drying at 40-50 ℃ to obtain the soil extractant;
after the soil extraction agent is used for treating lead-polluted soil for 7 days, the recovery rate of the soil extraction agent is 94-97%.
2. The use according to claim 1, wherein the dispersion conditions in step 2 are: dispersing at room temperature of 20-30 deg.C under shaking at 70-90rpm for 30-40 min.
3. The use of claim 1, wherein the pH of the solution in step 2 is adjusted to 10-11 using 10M NaOH solution.
4. The application of claim 1, wherein the soil extractant is prepared by compounding biomass charcoal and magnetic powder, wherein the mass ratio of the biomass charcoal to the magnetic powder is (2-2.5): 1, wherein the mass of the magnetic powder is Fe3O4The mass meter of (1).
5. The use of claim 1, wherein when the added mass of the soil extraction agent in the soil is 5%, the lead pollution concentration is reduced by 30.8-41.9% after the soil extraction agent treats the lead-polluted soil for 7 days.
6. The use of claim 1, wherein when the added mass of the soil extraction agent in the soil is 5%, the lead pollution concentration is reduced by 26.8-40.1% after the soil extraction agent treats the lead-polluted soil for 30 days.
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| CN102204436A (en) * | 2011-06-08 | 2011-10-05 | 南京农业大学 | Soil treatment method for inhibiting Cd/Pb absorption of rice in contaminated farm land |
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| CN103484125A (en) * | 2013-10-14 | 2014-01-01 | 厦门大学 | Soil improvement agent and improvement method of heavy metal lead-contaminated soil |
| CN104785519A (en) * | 2015-04-22 | 2015-07-22 | 清华大学 | Method for in situ fixation of vanadium ore polluted soil by modified charcoal |
| CN105039211A (en) * | 2015-07-07 | 2015-11-11 | 中国科学院城市环境研究所 | Polycyclic aromatic hydrocarbon removal composite material, and preparation method and use thereof |
| CN107824612A (en) * | 2017-11-04 | 2018-03-23 | 江西夏氏春秋环境股份有限公司 | A kind of Fe3O4The preparation method of base charcoal soil passivator |
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2018
- 2018-09-29 CN CN201811150937.1A patent/CN110961440B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102204436A (en) * | 2011-06-08 | 2011-10-05 | 南京农业大学 | Soil treatment method for inhibiting Cd/Pb absorption of rice in contaminated farm land |
| CN103331297A (en) * | 2013-07-02 | 2013-10-02 | 江苏省农业科学院 | Method for improving tea garden soil by utilizing biomass charcoals |
| CN103484125A (en) * | 2013-10-14 | 2014-01-01 | 厦门大学 | Soil improvement agent and improvement method of heavy metal lead-contaminated soil |
| CN104785519A (en) * | 2015-04-22 | 2015-07-22 | 清华大学 | Method for in situ fixation of vanadium ore polluted soil by modified charcoal |
| CN105039211A (en) * | 2015-07-07 | 2015-11-11 | 中国科学院城市环境研究所 | Polycyclic aromatic hydrocarbon removal composite material, and preparation method and use thereof |
| CN107824612A (en) * | 2017-11-04 | 2018-03-23 | 江西夏氏春秋环境股份有限公司 | A kind of Fe3O4The preparation method of base charcoal soil passivator |
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