JP2015024365A - Method for purifying soil, and adsorption member used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of easily purifying soil contaminated with heavy metal or cesium at a low cost.SOLUTION: Provided is a method for purifying soil contaminated by heavy metals or cesium, including: contacting an adsorption member 1 having an adsorption agent 11 and a water-absorbable holding part 12 holding the adsorption agent 11 at the inside with soil; and adsorbing heavy metals or cesium eluted from the soil on the adsorption member 11. The adsorption agent 11 is obtained by subjecting a woody biomass to pressure heating treatment.

Description

  The present disclosure relates to a soil purification method, and an adsorbing member and a kit used therefor.

  Due to the influence of mine development in the past, there is a region where the cadmium concentration in the soil of the field is high, and as a result, there is a problem that crops with a high cadmium concentration are produced. If a certain amount or more of cadmium is continuously ingested through crops for several decades, it may adversely affect kidney function. In order to reduce the cadmium concentration in agricultural crops, it is necessary to reduce the cadmium concentration in soil such as fields.

  As a method for reducing the cadmium concentration in soil, there is a plant purification method. The plant purification method is a method of reducing the concentration of cadmium in the soil by producing a crop with a large amount of cadmium absorbed. However, this method has a problem that the produced crop must be treated for purification, and a problem that 3 to 5 years are required for the production of the crop.

  As another method, there is a method of bringing in other soil which does not have a problem of contamination called “custom soil”. However, when carrying out customer land, there are problems that it is difficult to secure the soil used for the customer land and that it is costly to implement.

  As another method, a method is proposed in which lignin is spread on the soil, the cadmium component eluted from the soil by lignin is adsorbed, and the cadmium component is prevented from being eluted from the soil (Patent Document 1). However, in the method of Patent Document 1, in order to recover the lignin adsorbed with cadmium, it is necessary to recover the soil in which the lignin is sowed, and there is a problem that it is very complicated and expensive.

JP 2008-092907 A

Soil contamination has become a problem not only with cadmium described above, but also with other heavy metals and cesium, and there is a need for a purification method.
The present disclosure provides a method capable of purifying soil contaminated with heavy metals or cesium easily and at low cost.

  In one or a plurality of embodiments, the present disclosure is a method for purifying soil contaminated with heavy metal or cesium, and includes an adsorbent member having an adsorbent and a water-absorbing holding portion that holds the adsorbent inside. And a method for purifying the adsorbent obtained by pressurizing and heating the woody biomass, wherein the adsorbing member adsorbs the heavy metal or cesium eluted from the soil to the adsorbing member. About.

  According to the purification method of the present disclosure, soil contaminated with heavy metals or cesium can be purified easily and at low cost.

FIG. 1A is a perspective view of an adsorption member according to an embodiment of the present disclosure. FIG. 1B is a cross-sectional view of an adsorption member according to an embodiment of the present disclosure. FIG. 2A is an image of the experimental apparatus used in the example, and FIG. 2B is an image of the adsorption member after the experiment.

  The present disclosure can easily adsorb heavy metals or cesium eluted from soil by using an adsorbing member in which an adsorbent obtained by pressurizing and heating woody biomass is held inside a water-absorbing holding unit. Based on the knowledge that soil can be purified easily and at low cost.

[Soil purification method]
The present disclosure is a method for purifying soil contaminated with heavy metal or cesium (hereinafter also referred to as “heavy metal etc.”), and includes an adsorbent and a water-absorbing holding portion that holds the adsorbent inside. The method includes bringing a member into contact with the soil and adsorbing the heavy metal or cesium eluted from the soil to the adsorbing member, and the adsorbent is obtained by subjecting the woody biomass to pressure heat treatment. And a purification method (hereinafter, also referred to as “purification method of the present disclosure”). According to the purification method of the present disclosure, since the above-described adsorption member is used, in one or a plurality of embodiments, it is easy to collect the adsorption member after the purification treatment, and the soil is purified easily and at low cost. The effect that it is possible can be produced.

  In the present disclosure, “purifying the soil” refers to reducing the concentration of heavy metals or the like contained in the soil as compared to before the purification treatment. In the purification method of the present disclosure, examples of the heavy metal include cadmium, arsenic, lead, chromium, mercury, selenium, and copper in one or more embodiments.

  The purification method of the present disclosure includes bringing the adsorbing member into contact with soil contaminated with heavy metal or the like. In the purification method of the present disclosure, the “adsorbing member” includes an adsorbent and a water-absorbing holding unit that holds the adsorbent inside.

<Adsorbent>
In the purification method of the present disclosure, the “adsorbent” is obtained by pressurizing and heating woody biomass. In one or a plurality of embodiments, the woody biomass includes leaves such as conifers, broadleaf trees, and vegetation, bark, branches, and wood. The lignin obtained has a different structure depending on the type of woody biomass used as a raw material. When softwood is used as a raw material, a lignin derivative mainly containing a guaiacylpropane structure is obtained as one or a plurality of embodiments. In the case of using hardwood as a raw material, in one or a plurality of embodiments, a lignin derivative mainly containing a guaiacylpropane structure and a silylalkylpropane structure is obtained. When vegetation is used as a raw material, a lignin derivative mainly containing a guaiacylpropane structure, a silylkillpropane structure, and a 4-hydroxyphenylpropane structure is obtained. As for the shape of the adsorbent, in one or more embodiments, a powder form may be mentioned.

  In the purification method of the present disclosure, examples of the pressure heat treatment include subcritical water treatment, supercritical water treatment, and explosion treatment in one or a plurality of embodiments. In one or a plurality of embodiments, the adsorbent is preferably lignin or a lignin derivative obtained by subjecting woody biomass to subcritical water treatment or supercritical water treatment from the viewpoint of improving the adsorption effect of heavy metals and the like. It does not specifically limit as a shape of the woody biomass to process, In one or some embodiment, a powder etc. are mentioned.

  In one or a plurality of embodiments, the subcritical water or supercritical water treatment is to heat a reaction vessel containing woody biomass and water under pressure and treat the water inside the reaction vessel as subcritical water or supercritical water. Can be done by. The temperature condition is 180 to 350 ° C., 200 to 300 ° C., or 230 to 300 ° C. in one or more embodiments. The pressure condition is 1.0 to 16 MPa, 2.0 to 10 MPa, or 2.8 to 10 MPa in one or more embodiments.

  In one or a plurality of embodiments, the blasting treatment can be performed by treating the woody biomass under high temperature and high pressure, and then instantaneously reducing the pressure. By this treatment, the plant tissue is destroyed and fiberized. The blasting treatment can be performed in a gas that can be pressurized in one or more embodiments. In one or a plurality of embodiments, the blasting treatment is performed in the presence of water vapor, nitrogen, carbon dioxide, and the like. The temperature condition is 100 to 300 ° C or 180 to 230 ° C in one or more embodiments. The pressure condition is 0.1 to 10 MPa or 1 to 3 MPa in one or more embodiments. The processing time is 1 to 60 minutes or 1 to 10 minutes in one or more embodiments.

  In one or a plurality of embodiments, the adsorbent can be obtained as a filtrate by subjecting powdery woody biomass to pressure heat treatment, followed by filtration to remove carbohydrates such as hemicellulose and cellulose. The obtained filtrate may be used as an adsorbent as it is, or the obtained filtrate is solvent-extracted and separated into low-molecular lignin and polymer lignin, and polymer lignin may be used as the adsorbent. Good. Examples of the solvent include acetone and methanol in one or more embodiments. Solvent extraction can be normally performed at normal temperature, and is 15-40 degreeC or 20-30 degreeC in one or some embodiment. In the present disclosure, “polymer lignin” refers to lignin that is insoluble in a solvent and does not melt by heating at 200 ° C. or lower in one or more embodiments.

  Examples of the adsorbent include chlorolignin, nitrolignin, ligninsulfonic acid, and thiolignin in one or more embodiments. Examples of lignin sulfonic acid include lignin sulfonate such as calcium salt, magnesium salt, and sodium salt in one or more embodiments.

<Holding part>
In the purification method of the present disclosure, the “holding unit” can hold the adsorbent inside and has water absorption. In the present disclosure, the term “water absorption” refers to the property of sucking water in the fiber or the material itself, or the fiber or material itself does not suck in the water, but sucks water in a gap in the fiber or the material or a gap between adjacent fibers or the material. Refers to nature. As for a holding | maintenance part, a nonwoven fabric, a woven fabric, etc. are mentioned as one or some embodiment. Examples of the material of the holding part include one or a plurality of embodiments, such as cotton, polypropylene, polyethylene, polyvinyl alcohol, polyamide, natural fiber, PET, recycled fiber, carbon fiber, glass fiber, ceramic, and the like. Can be mentioned. Examples of natural fibers include cellulose fibers and protein fibers in one or more embodiments.

  Examples of the shape of the holding part include a cylindrical shape, a rod shape, and a honeycomb shape in one or a plurality of embodiments.

  In the purification method of the present disclosure, from the point of improving purification efficiency, in one or a plurality of embodiments, at least a part of the adsorption member is buried in the soil, or a part of the adsorption member is buried in the soil. It is preferable to use other parts exposed from the soil.

  In the purification method of the present disclosure, the adsorbing member can support the holding unit in one or a plurality of embodiments from the viewpoint of facilitating the arrangement of the adsorbing member on the soil and preventing damage of the adsorbing member during processing. It may have a support. In one or a plurality of embodiments, the support has a cylindrical shape and can hold the holding portion in the hollow portion. In one or a plurality of embodiments, the support is not particularly limited as long as it supports the holding portion and has water permeability. Examples of the support include, in one or more embodiments, cocoons, bamboo baskets, nets, mesh-like objects, and honeycomb-like objects.

  In the purification method of the present disclosure, in one or a plurality of embodiments, in order to improve purification efficiency, in one or a plurality of embodiments, one end of the cylindrical adsorption member is buried in the soil, and the holding unit and the soil are in contact with each other, It is preferable to arrange so as to protrude from the soil.

  The purification method of the present disclosure includes adsorbing a heavy metal or the like eluted from soil on an adsorbing member. In one or a plurality of embodiments, the purification method of the present disclosure may include eluting heavy metals and the like from soil. In one or a plurality of embodiments, elution of heavy metals and the like from the soil can be performed using an acidic substance or salt, and preferably the acidic substance or salt is sprayed on the soil, or the acidic substance inside the holding unit. Or it can carry out by making salt hold | maintain. In one or a plurality of embodiments, acidic substances or salts include solutions or solids having a pH of 1 to 7, and it is easy to spray and can be efficiently eluted. preferable. In one or a plurality of embodiments, the acidic substance or salt includes calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium sulfate, sodium acetate, calcium acetate, magnesium acetate, ammonium sulfate, ethylenediaminetetraacetic acid, citric acid, and phytic acid. , Hydrochloric acid, nitric acid, sulfuric acid and acetic acid.

  Since the purification method of the present disclosure improves the purification efficiency, in one or a plurality of embodiments, the surface of the soil to be treated may include covering with a sheet having an opening in which the adsorption member can be arranged. Good. The sheet is preferably impermeable in one or a plurality of embodiments from the viewpoint of improving purification efficiency and suppressing evaporation of heavy metals and the like eluted from the soil to the outside. Examples of the material of the sheet include vinyl, rubber, and resin in one or a plurality of embodiments.

[Adsorption member]
As another aspect, the present disclosure is an adsorbing member for use in the purification method of the present disclosure, which is an adsorbent obtained by pressurizing and heating woody biomass, and a water absorbing property that holds the adsorbent inside. And a holding member (hereinafter, also referred to as “the suction member of the present disclosure”). According to the suction member of the present disclosure, the purification method of the present disclosure can be easily performed. The suction member of the present disclosure is the same as the suction member used in the purification method of the present disclosure.

[Soil purification kit]
As another aspect, the present disclosure is a soil purification kit (hereinafter also referred to as “kit of the present disclosure”) including the adsorption member of the present disclosure and a soil cover sheet having an opening in which the adsorption member can be disposed. About. According to the kit of the present disclosure, the purification method of the present disclosure can be easily performed. In the kit of the present disclosure, the adsorbing member and the sheet are the same as those used in the purification method of the present disclosure.

  Hereinafter, the present disclosure will be described with reference to preferred embodiments. However, it goes without saying that the present disclosure is not construed as being limited to the following embodiments.

(Embodiment 1)
FIG. 1A is a perspective view of an adsorption member according to an embodiment of the present disclosure, and FIG. 1B is a cross-sectional view of the adsorption member according to an embodiment of the present disclosure. The adsorbing member 1 according to Embodiment 1 includes an adsorbent 11, a holding unit 12 that holds the adsorbent 11 inside, and a support 13 that supports the holding unit 12. The support 13 is cylindrical and is formed so as to cover the side surface of the holding portion 12.

  The holding unit 12 includes a portion (hereinafter also referred to as “adsorbent holding portion”) 111 that holds the adsorbent 11, and an adsorption assisting unit 112. By having the adsorption assisting part 112, it is possible to improve adsorption of heavy metals and the like by the adsorption member 1 and improve purification efficiency. The adsorption assisting part 112 is formed below the adsorption member 1 and exposed from the support 13. That is, the adsorption | suction auxiliary | assistance part 112 contacts directly with soil, when the adsorption | suction member 1 is embed | buried in soil. Although the shape of the adsorption | suction auxiliary | assistant part 112 is not specifically limited, In one or some embodiment, strip shape, brush shape, mesh shape, etc. are mentioned, From the point which improves adsorption | suction efficiency, strip shape is preferable. .

The magnitude | size of the adsorption | suction member 1 is not specifically limited. The height of the adsorbent holding portion 111 is 10 to 40 cm, or 20 to 30 cm in one or more embodiments. The volume of the adsorbent holding portion 111, in one or more embodiments, 10～500Cm ^3, or 25~250cm ^3. The length of the adsorption assisting part 112 can be appropriately determined according to the size of the adsorption member 1, and in one or a plurality of embodiments, is 30 to 40 cm, or 10 to 20 cm. The amount of the adsorbent 11 held by the adsorbing member 1 is 1 to 100 g / piece, or 5 to 50 g / piece in one or more embodiments.

The amount of the adsorbent 11 held in the holding unit 12 can be appropriately determined according to the size of the adsorbing member 1, and in one or more embodiments, 0.1 to 0.1 per unit volume of the adsorbent holding portion 111. 0.5 g / cm ^3, or 0.2 to 0.3 g / cm ^3.

  Below, one Embodiment of the purification method of the soil using the adsorption | suction member of this Embodiment 1 is described.

First, an acidic substance or salt is sprayed on the soil to be treated. Thereby, heavy metals etc. can be efficiently eluted from soil. The density | concentration of the acidic substance or salt to disperse | distributes is 0.01-0.5M or 0.05-0.1M in one or some embodiment. In one or a plurality of embodiments, the amount of the acidic substance or salt to be dispersed is 1 to 20 / m ² or 5 to 15 L / m ² per unit area of the soil to be treated.

Next, the sheet is covered with the soil to be treated, and one end of the adsorption member is embedded in the soil through the opening of the sheet. Thereby, the heavy metal eluted from the soil can be efficiently adsorbed to the adsorption member. In one or a plurality of embodiments, the adsorbing member preferably buryes at least 1/5, 1/4, or 1/2 of the adsorbing member in the soil. The number of adsorbing members embedded in the soil is 1 to 15 / m ² , or 5 to 10 / m ² in one or more embodiments. The number and position of the opening portions of the sheet are not particularly limited, and can be appropriately determined according to the area of the soil to be treated and the contamination status of the soil. The opening part of a sheet | seat can be suitably determined according to the number of the adsorption | suction members embed | buried in one or some embodiment. The treatment period can be appropriately determined according to soil contamination and the like. In one or a plurality of embodiments, the treatment period is 1 week to 4 weeks, or 1 month to 6 months.

  If necessary, from the point of improving the purification efficiency, after disposing the adsorbing member, the acidic substance or salt may be sprayed again.

  After completion of the purification process, the adsorbing member that adsorbs heavy metal or the like is collected. The recovered adsorbing member may recover heavy metal or the like by incinerating the internal adsorbent.

(Embodiment 2)
The adsorbing member in the second embodiment includes an adsorbent, an acidic substance or salts, a holding part that holds the adsorbent and acidic substance or salts inside, and a support that supports the holding part. The adsorbing member in the second embodiment has the same configuration as the adsorbing member in the first embodiment except that the holding unit holds an acidic substance or salts in addition to the adsorbent.

Acidic substances or salts are, in one or more embodiments, solutions, solids, and powders. In one or a plurality of embodiments, the amount of the acidic substance or salt held in the holding unit is 0.001 to 1 g / cm ³ or 0.01 to 0.5 g / per unit volume of the adsorbent holding portion 111. cm ³ .

  Below, one Embodiment of the purification method of the soil using the adsorption | suction member of this Embodiment 2 is described.

  An adsorption member is embedded in the soil to be treated so that one end is located in the soil. Then, water or the like may be sprayed on the soil, or water or the like may not be sprayed when natural rainfall can be expected or when the soil is already sufficiently wet. From the viewpoint of promoting the elution of heavy metals and the like from the soil and improving the purification efficiency, it is preferable to spray water, acidic substances or salts. Moreover, you may cover a sheet | seat surface to be processed from the point which improves purification efficiency. From the viewpoint of improving the purification efficiency, the sheet is preferably provided with an opening corresponding to the position of the embedded adsorption member, and is covered so that one end of the adsorption member is exposed from the opening. Then, the adsorbing member is maintained in a state embedded in the soil for a predetermined period. Thereby, the heavy metal etc. in soil can be made to adsorb | suck to adsorption agent, and soil purification can be performed.

  If necessary, from the point of improving the purification efficiency, after disposing the adsorbing member, an acidic substance, salts, water, or the like may be sprayed again.

The present disclosure further relates to one or more of the following embodiments.
[1] A method for purifying soil contaminated with heavy metals or cesium,
Adsorbing an adsorbing member having an adsorbent and a water-absorbing holding part that holds the adsorbent inside, and contacting the adsorbing member with heavy metal or cesium eluted from the soil. Including
The said adsorption agent is a purification method obtained by pressurizing and heating woody biomass.
[2] The pressure heat treatment is subcritical water or supercritical water treatment,
The purification method according to [1], wherein the adsorbent is powdered lignin obtained by subjecting woody biomass to subcritical water or supercritical water treatment.
[3] The adsorbing member is a cylindrical adsorbing member having a cylindrical support, and the holding portion is disposed in a hollow portion of the cylindrical support,
The cylindrical adsorbing member includes disposing the cylindrical adsorbing member so that one end is buried in soil, the holding unit and the soil are in contact with each other, and the other end protrudes from the soil, according to [1] or [2] Purification method.
[4] The purification method according to any one of [1] to [3], comprising eluting heavy metal or cesium from the soil using an acidic substance or salts.
[5] The purification method according to any one of [1] to [4], further comprising spraying an acidic substance or salts on the soil.
[6] The purification method according to any one of [1] to [5], wherein the holding unit further holds an acidic substance or salts therein.
[7] Covering the soil surface to be treated with a sheet having an opening in which the adsorbing member can be disposed, and one end of the adsorbing member is buried in the soil in the opening of the sheet. The purification method according to any one of [1] to [6], including disposing the adsorbing member such that the holding unit contacts the soil and the other end protrudes from the sheet.
[8] An adsorption member for use in the purification method according to any one of [1] to [7],
An adsorbent obtained by pressurizing and heating woody biomass;
An adsorbing member having a water absorbing holding part for holding the adsorbent inside.
[9] A kit for use in the purification method according to any one of [1] to [7],
[8] The adsorbing member according to
A soil purification kit including a soil cover sheet having an opening in which the adsorption member can be disposed.

  Hereinafter, the present disclosure will be described with reference to examples and reference examples, but the present disclosure is not limited to the following examples.

[Production of adsorption member]
Cedar sawdust and water were placed in a 10 L autoclave so as to have a solid content of 10% by mass, and subjected to subcritical water treatment at 230 ° C. and 2.8 MPa. Thereafter, pressure filtration was carried out, and 10 times the volume of acetone was added to the obtained solid matter, and immersed at 23 ° C. overnight. Further filtration was performed to obtain a solid after filtration (powdered lignin derivative) as an adsorbent. After 5 g of the obtained adsorbent is put into a cotton bag (length 34 cm x width 8.5 cm), a bamboo basket (length 7.5 cm x width 8.5 cm) is wound around the adsorbent to form a cylinder Was made. In addition, as a cotton-type bag, although the adsorbent did not leak, what used the solution was permeable.

Example 1
Using the produced adsorbing member, 200 mL conical beaker and soil, an experimental apparatus shown in FIG. 2A was produced, and the soil purification effect of the adsorbing member was confirmed. As for the soil, cadmium nitrate was added to horticultural soil purchased at a home center to adjust the cadmium concentration to 100 to 130 ppm, and 40 g thereof was placed in a conical beaker. 50 mL of any of the solutions shown in Table 1 below was sprayed on the soil in the conical beaker, and the adsorbing member was placed in the beaker. In addition, in order to suppress evaporation from between the adsorption member and the conical beaker, a rubber stopper was disposed between the adsorption member and the conical beaker. The soil was dried with an electric dryer at 100 ° C. for 12 hours. After repeatedly spraying and drying the solution 20 times, the adsorbing member was taken out. A heavy metal elution test was conducted on the soil from which the adsorbing member was taken out. The results are shown in Table 1 below. Further, a blank was obtained by performing the same test except that the adsorbing member was not disposed and only the soil was used and the upper part of the conical beaker was opened. In Table 1, RSD refers to relative standard deviation.

[Dissolution test]
The dissolution test was conducted as follows.
Soil :
After adding 6 g of soil and 200 mL of 1M hydrochloric acid to a 500 ml separatory funnel and stirring for 2 hours with a shaker (250 shake min ⁻¹ ), the solution was filtered and the cadmium concentration of the filtrate was measured with an atomic absorption photometer. It was measured. One sample was subjected to a dissolution test three times, and a relative standard deviation RSD (= (standard deviation / average value) × 100) was calculated.
Lignin :
After adding 1 g of lignin and 33.3 mL of 1M hydrochloric acid to 100 mL polybin and stirring for 2 hours with a shaker (250 shaking min ⁻¹ ), the solution was filtered and the cadmium concentration of the filtrate was measured with an atomic absorption photometer. It was measured. One sample was subjected to a dissolution test three times, and a relative standard deviation RSD (= (standard deviation / average value) × 100) was calculated.

  The taken-out adsorbing member was divided into three equal parts as shown in FIG. 2B, and cadmium was measured for lignin contained in each part. The cadmium concentration was measured by the above dissolution test method. The results are shown in Table 2 below.

  As shown in Tables 1 and 2, in Examples 1-1 and 1-2 in which the purification method of the present disclosure was performed, the soil could be purified by adsorbing cadmium eluted from the soil to the adsorbent.

(Example 2)
The soil purification effect was confirmed in the same manner as in Example 1 except that cesium chloride was used instead of cadmium nitrate, the cesium concentration in the soil was 24 ppm, and the solution sprayed on the soil was the solution shown in Table 3 below. . The cesium concentration in the soil after the purification treatment is shown in Table 3 below, and the cesium concentration in the adsorbing member is shown in Table 4. The cesium concentration in the soil was measured with an inductively coupled plasma mass spectrometer after the elution test was performed on the cesium concentration in the soil and lignin.

  As shown in Tables 3 and 4, in Example 2 in which the purification method of the present disclosure was performed, the soil could be purified by adsorbing cesium in the soil to the adsorbent.

Claims (9)

A method for remediating soil contaminated with heavy metals or cesium,
Bringing an adsorbent and an adsorbing member having a water-absorbing holding part that holds the adsorbent inside into contact with the soil, and adsorbing heavy metal or cesium eluted from the soil onto the adsorbent. Including
The said adsorption agent is a purification method obtained by pressurizing and heating woody biomass. The pressure heat treatment is subcritical water or supercritical water treatment,
The purification method according to claim 1, wherein the adsorbent is powdered lignin obtained by subjecting woody biomass to subcritical water or supercritical water treatment. The adsorbing member has a cylindrical support, and is a cylindrical adsorbing member in which the holding portion is disposed in a hollow portion of the cylindrical support,
The purification method according to claim 1, comprising disposing the cylindrical adsorbing member such that one end is buried in soil, the holding unit and the soil are in contact with each other, and the other end protrudes from the soil. .   The purification method according to any one of claims 1 to 3, comprising eluting heavy metal or cesium from the soil using an acidic substance or salts.   The purification method according to claim 1, comprising spraying an acidic substance or a salt on the soil.   The purification method according to any one of claims 1 to 5, wherein the holding unit further holds an acidic substance or a salt therein. Covering the surface of the soil to be treated with a sheet having an opening in which the adsorbing member can be disposed, and one end of the adsorbing member is buried in the soil in the opening of the sheet, The purification method according to any one of claims 1 to 6, further comprising disposing the adsorbing member so as to come into contact with soil and the other end protrudes from the sheet. An adsorption member for use in the purification method according to any one of claims 1 to 7,
An adsorbent obtained by pressure heating treatment of woody biomass,
An adsorbing member having a water absorbing holding part for holding the adsorbent inside. A kit for use in the purification method according to any one of claims 1 to 7,
The adsorbing member according to claim 8;
A soil purification kit comprising: a soil cover sheet having an opening in which the adsorption member can be disposed.