JP4883569B2 - Metal elution method, metal analysis and metal elution apparatus using the metal elution method - Google Patents

Description

  The present invention relates to a metal elution method for eluting a metal in an analysis sample into pressurized hot water, a metal analysis method using the metal elution method as a pretreatment, and an apparatus for performing the metal elution method.

Conventionally, qualitative and quantitative analysis of metals has been performed for the purpose of examining heavy metal contamination such as natural resources, sediment, soil or industrial waste.
Examples of the analysis method include atomic absorption analysis, ICP analysis, and ICP mass spectrometry. In order to perform these analyses, it is necessary to elute the metal in the analysis sample in advance.

Currently, metal elution methods generally used include dry decomposition methods, wet decomposition methods, and microwave thermal decomposition methods described in Non-Patent Document 1.
On the other hand, there is a hydrothermal treatment method in which an analysis sample is placed in water and heated for a certain period of time to elute the metal in water (see Patent Document 1).
JP 2005-283508 A Masao Mishima, “Measurement of trace metals in the environment, sample pretreatment”, Tokyo Chemical Doujin

By the way, the metal analysis has a purpose of measuring the kind and concentration of a metal harmful to the human body contained in the soil, for example, and therefore requires accuracy.
However, the above-described metal elution method has a small effect of elution of metal from a sample and is not necessarily efficient. Therefore, in the conventional metal elution method, it is difficult to reliably specify the type and weight of the metal contained in the organic substance.

The present invention has been developed to solve the above problems.
That is, a metal elution method for eluting a metal in a sample in a liquid (pressurized hot water) as much as possible, a metal analysis method using the metal elution method as a pretreatment, and a metal elution apparatus for performing the metal elution method The purpose is to provide.

  As a result of intensive studies based on the background of the problems as described above, the present inventor brought the powdered sample into contact with pressurized hot water while being dispersed in the pressurized hot water, and The inventors have found that the above-mentioned problems can be solved by further bringing pressurized hot water into contact with a powdery sample adhering to a filter, and have completed the present invention based on the findings.

That is, the present invention is (1) a metal elution method for eluting a metal contained in a sample into pressurized hot water, wherein the sample is brought into contact with pressurized hot water while being dispersed in the pressurized hot water. A first contact step for eluting the metal, and a second contact step for further eluting the metal by contacting the sample captured by the filter with pressurized hot water , the first contact step and the second is performed in a state in which the contacting step is constantly flowing through the pressurized hot water, the pressurized hot water is, 10 MPa pressurized below, der Ru metal elution method which has been heated in the range of 120 to 200 [° C. Exist.

Moreover, this invention exists in the metal elution method of the said (1) description to which an acid is added, before using for the metal analysis the pressurized hot water containing the eluted metal (2).

Moreover, this invention is ( 3 ) The metal elution as described in said (1) or (2) whose particle size of the sample used by said 1st contact process and said 2nd contact process is a powder form with a particle size of 50-800 micrometers. Lies in the way.

The present invention resides in metal analysis method of analyzing any to one performs metal elution method described, processing the resulting metal is eluate (4) pre-treated as above (1) to (3) .

The present invention (5) above (1) to (3) a metal dissolution unit metal dissolution process is conducted according to any one of the metals contained in the sample to the pressurized hot water A metal eluting device for eluting, a high pressure pump for compressing and transporting water for eluting the metal contained in the sample, a heater for heating the water compressed and transported by the high pressure pump, and the metal eluting device A cooling device that cools the processing liquid that has flowed out from the outlet portion of the liquid crystal, and a filtration device that removes fine particles from the processing liquid cooled by the cooling device , wherein the metal eluting device is a main body portion in which the sample is enclosed And an inlet part through which the main body part allows the pressurized hot water to flow into the main body part, a first joint member detachably attached to the inlet part, and an outlet part through which the pressurized hot water flows out of the main body part. When the second joint member for removably to said outlet , Attached to the outlet section, have a, a filter for capturing the sample resides in a metal dissolution apparatus wherein the filter is attached Ru replaceable der between the second joint member and the outlet portion.

In addition, as long as the objective of this invention is met, the structure which combined said (1) to ( 5 ) suitably is also employable.

  The metal elution method of the present invention includes a first contact step in which a sample is contacted in a state where it is dispersed in pressurized hot water, and a method in which the sample is further brought into contact with pressurized hot water in a state where the powder is captured by a mesh filter. Since the metal elution method comprises a two-contact process, a larger amount of metal than the amount of metal eluted by the conventional metal dissolution method can be effectively eluted.

  The metal elution method of this invention can elute a metal more efficiently by performing a 1st contact process and a 2nd contact process in the state which flowed pressurized hot water regularly.

FIG. 1 is a diagram showing the steps of the metal elution method. The metal elution method according to the present embodiment is employed, for example, as a pretreatment for metal analysis, and a sample (for example, natural resources, sediment, soil, industrial waste, etc.) is dispersed in pressurized hot water. In this state, the metal elution method includes a first contact step in which the hot water is brought into contact with the pressurized hot water and a second contact step in which the sample adhering to the filter is further brought into contact with the hot hot water.
Here, pure hot water is used for the metal elution method according to the present embodiment, and therefore, it does not contain impurities, and since the ionic product and the solubility of the metal are large, the metal is eluted from the sample. Is preferred.

  According to the metal elution method according to the present embodiment, a larger amount of metal than the amount of metal eluted into the liquid (acid) by the conventional metal elution method can be eluted.

(First contact process)
The first contact step is a step in which a sample to be analyzed is dispersed in pressurized hot water, and the sample dispersed in the pressurized hot water is brought into contact with the pressurized hot water. By this contact, the metal in the sample is eluted in the pressurized hot water.
Since the sample to be analyzed is used in a powder state, the contact area between the sample and the pressurized hot water increases as a whole as compared with the case where the sample to be analyzed is in a lump shape. As a result, a larger amount of metal is eluted in the pressurized hot water.

In this metal elution method, the pressurized hot water is in a state of flowing in the partitioned space at a predetermined flow rate, so that the powdery sample moves in all directions in the pressurized hot water.
Therefore, the contact interface between the sample and the pressurized hot water always changes (the accumulated contact area increases), and as a result, the metal in the sample is efficiently eluted in the treatment liquid.

(Second contact process)
The second contact step is a step in which pressurized hot water is vigorously brought into contact with the sample captured by the filter through the first contact step.
After the first contact process of the first stage, the second contact process of the second stage is performed again, thereby increasing the chance of contact between the sample and the pressurized hot water and adding a larger amount of metal. It can be eluted in pressurized hot water.
In addition, in the second contact step, the sample is brought into pressure contact with the pressurized hot water, so that the pressurized hot water and the fine irregularities on the sample surface come into contact with each other. Therefore, the metal is efficiently eluted in the treatment liquid.
Hereinafter, the pressurized hot water that has undergone the first contact step and the second contact step is referred to as a “treatment liquid”. The treatment liquid may contain fine particles such as hemicellulose, cellulose, and lignin.

The pressurized hot water used in the metal elution method according to this embodiment is preferably one that is pressurized at 10 MPa or less and heated in the range of 120 to 200 ° C.
When the temperature of the pressurized hot water is lower than 120 ° C., the metal contained in the sample is not easily eluted.
When the temperature of the pressurized hot water is higher than 200 ° C., the state is close to the critical state, and corrosion is likely to occur inside the machine that performs the metal elution method according to the present embodiment.

It is preferable to use a powder sample having a particle size of 50 to 800 μm. By setting the particle size of the sample within the above range, the contact area between the pressurized hot water and the sample is increased within a range that allows filtration with a filter, and the metal is efficiently eluted.
Specifically, the first contact step and the second contact step described above are performed in a metal eluting device described later.

  FIG. 2 is a schematic view showing the entire metal elution apparatus for performing the metal elution method according to the present embodiment. The metal elution apparatus shown in FIG. 2 includes a high-pressure pump 1, a heater 2, a metal elution device 3, a cooler 4, and a back pressure valve 5. These devices are connected in series in the above order by flow path members such as pipes.

The high-pressure pump 1 is connected to a storage tank 6 in which water (pure water) is stored. The high-pressure pump 1 sucks water from the storage tank 6 and compresses and transfers it to the heater 2.
The pressure applied to the water by the high-pressure pump 1 is set to a pressure equal to or higher than the saturated vapor pressure at a desired water temperature.

The heater 2 is a device that heats the compressed water sent from the high-pressure pump 1 to a desired temperature.
For example, a heat exchanger or a heater is used as the heater 2. The water heated by the heater 2 becomes pressurized hot water and is sent to the metal eluting device 3.

The metal eluting device 3 has a main body part for enclosing a sample, the main body part is an inlet part for allowing pressurized hot water to flow into the main body part, and for allowing the pressurized hot water to flow out of the main body part. And an outlet portion. Further, a filter for capturing the sample is attached to the outlet portion.
The first contact step and the second contact step described above are performed in the main body, and the metal is eluted from the enclosed sample.

The pressurized hot water containing the eluted metal, that is, the treatment liquid flows out from the metal elution device 3 and is then sent to the cooler 4 where it is cooled to about room temperature.
The specific structure of the cooler 4 is not particularly limited, and for example, a heat exchanger can be used.
In addition, by providing the back pressure valve 5 behind the cooler 4, the pressure in the apparatus connected upstream of the back pressure valve 5 can be kept constant.

The processing liquid that has passed through the cooler 4 is placed in a receiving container 7 and subjected to metal analysis.
In addition, before using a process liquid for a metal analysis, a more exact metal analysis can be performed by removing the microparticles | fine-particles contained in a process liquid. As a means for removing the fine particles, for example, the treatment liquid is filtered using a filter such as a membrane filter.

Such a filtering means can also be provided in the metal elution apparatus, and in that case, the treatment liquid discharged from the metal elution apparatus can be analyzed as it is.
The type of metal eluted in the treatment liquid and its weight are measured by a metal analysis method such as ICP emission analysis.

In addition, it is preferable to add an acid to the treatment liquid (hereinafter referred to as “acid treatment”) before removing the fine particles.
Among the fine particles contained in the treatment liquid, organic substances such as sugar are decomposed into substances that do not affect the result of metal analysis by acid treatment, so that metal analysis with higher accuracy can be performed.

Here, FIG. 3 is a schematic view showing in cross section the above-described metal eluting device, which is a portion for performing metal elution.
As shown in FIG. 3, a powdered sample is sealed in the partitioned space of the metal eluting device 3. The metal eluting device 3 includes a main body 31, a first joint member 32 that is removable at the entrance of the main body, and a second joint member 33 that is also removable at the outlet of the main body.

  The first joint member 32 and the second joint member 33 are attached to the main body 31 in an extrapolated state by screwing. Therefore, for example, the powdered sample can be sealed in the main body from the outlet portion by removing the second joint member 33 from the main body portion 31, or the main body from the inlet portion by removing the first joint member 32 from the main body portion 31. It can also be enclosed in the part 31.

The first joint member 32 fixes the flow path member connecting the heater 2 and the metal eluting device 3 to the metal eluting device 3.
The second joint member 33 fixes the flow path member connecting the cooler 4 and the metal eluting device 3 to the metal eluting device 3.
In this way, by attaching the first joint member 32 and the second joint member 33, the gap between the flow path member and the metal eluting device 3 can be closed, so that the pressure inside the metal eluting device 3 is stable. Can be made.

  A filter 34 is attached to the outlet of the main body 31, and the filter 34 captures a sample contained in the processing liquid flowing in the main body 31. Therefore, only the processing liquid is sent to the cooler 4 from the outlet.

The filter 34 can be easily exchanged for a new one by being interposed between the second joint member 33 and the main body 31 and screwed together.
As the filter 34, a filter that can sufficiently capture the sample powder having a particle size of about 50 to 800 mm is used, and stainless steel is preferable from the viewpoint of rust prevention.

On the other hand, the auxiliary filter 35 interposed between the first joint member 32 and the main body portion 31 can be easily replaced by screwing the first joint member 32 and the main body portion 31 together.
The auxiliary filter 35 serves as a lid for preventing the sample from leaking out from the metal eluting device 3.

  Hereinafter, although an Example is given and the metal elution method of this invention is shown, this invention is not limited to a following example.

Example 1
In this example, metal elution was performed using a metal elution apparatus having the same structure as the metal elution apparatus shown in FIG.
As the high-pressure pump 1, MINICHMI PUMP manufactured by Japan Precision Science Co., Ltd. was used.
The heating method of the heater _{2 is} to fill a metal salt (KNO ₃ : NaNO ₂ : NaNO ₃ = 53: 40: 7) in a container installed in a mantle heater (GBR-30, manufactured by Okaden Electric Co., Ltd.) A pipe is immersed in a mantle heater. The temperature control of the heater 2 is performed by a temperature controller (manufactured by SHIMADEN, SR32).
As the cooler 4, a custom-made cooler of a tubular double cooling tube type was used.
As the back pressure valve 5, a back pressure valve manufactured by TESCOM, model number 26-1762-24-084 was used.
A pipe having a diameter of 6.3 mm (manufactured by SUS316) was used as a flow path member connecting these devices.

As the metal eluting device 3, a stainless steel cylindrical container having a diameter of 10.2 mm and a length of 46.7 mm (internal volume 3.8 ml) was used, and a flow path member was attached to the bottom surface of the container. Thereby, the metal eluting device 3 is connected to the heater 2 and the cooler 4.
A stainless sintered filter having a pore diameter of 5 μm was used as a filter, and the sintered filter was attached to both bottom surfaces of the metal eluting device 3.

Next, a method for metal analysis will be described.
A rice husk was used as a sample to be analyzed, and after pulverization, it was sieved, and 0.8 g of the one having a particle size of about 250 to 650 μm was enclosed in the metal eluting device 3.

  Next, the metal eluting device 3 was connected to the metal eluting device, and the pressure in the metal eluting device was adjusted to 5 MPa using the back pressure valve 5. After adjusting the pressure in the metal elution apparatus, pure water was fed into the heater 2 at a flow rate of 10 ml / min using the high-pressure pump 1.

  The pure water sent to the heater 2 was heated to 200 ° C. by the heater 2 and was sent to the metal eluting device 3 as pressurized hot water.

  The pressurized hot water fed to the metal eluting device 3 reacted therewith with the sample to be analyzed, became a treatment liquid, and flowed out of the metal eluting device 3. The treated liquid that flowed out was immediately cooled to 10 ° C. by the cooler 4, passed through the back pressure valve 5, and then collected in the receiving container 7.

  The collected treatment liquid was filtered through a membrane filter having a pore size of 0.5 μm, and the obtained filtrate was subjected to metal analysis by ICP emission method. Table 1 shows the elution amounts of various metals measured by metal analysis in terms of elution amounts (μg) per 1 g of the sample.

(Example 2)
Except that the sample to be analyzed was barley straw, metal analysis was performed in the same procedure as in Example 1, and the elution amounts of various metals were measured. Table 1 shows the measured elution amount converted to the elution amount per 1 g of the sample.

(Example 3)
Except that the sample to be analyzed was eucalyptus, metal analysis was performed by the same procedure as in Example 1, and the elution amounts of various metals were measured. Table 1 shows the measured elution amount converted to the elution amount per 1 g of the sample.

(Comparative Example 1)
[Wet decomposition method]
As a sample to be analyzed, 1.0 g of rice husk (particle size: 250 to 650 μm) shown in Example 1 was placed in a sealable Teflon (registered trademark) metal eluting device, and then 25 mL of 1N nitric acid was added. Was sealed. Subsequently, the metal eluent was transferred into boiling water and boiled for 1 hour.

  After completion of boiling, the metal eluting device was cooled to room temperature, and the treatment liquid in the metal eluting device was recovered. The collected treatment liquid was filtered through a membrane filter having a pore size of 0.5 μm, and the obtained filtrate was subjected to metal analysis by ICP emission method. Table 1 shows the elution amounts of various metals measured by metal analysis in terms of elution amounts (μg) per 1 g of the sample.

(Comparative Example 2)
Except that the sample to be analyzed was barley straw, metal analysis was performed in the same procedure as in Comparative Example 1, and the elution amounts of various metals were measured. Table 1 shows the measured elution amount converted to the elution amount per 1 g of the sample.

(Comparative Example 3)
Except that the sample to be analyzed was eucalyptus, metal analysis was performed in the same procedure as in Comparative Example 1, and the elution amounts of various metals were measured. Table 1 shows the measured elution amount converted to the elution amount per 1 g of the sample.

(Comparative Example 4)
[Hydrothermal treatment]
0.3 g of chaff (particle size 250 to 650 μm) similar to that shown in Example 1 and 3.0 ml of pure water were put in a batch metal elution device made of stainless steel having an internal volume of 6.0 ml as an analysis target sample. .
Subsequently, the air in the metal eluting device was replaced with nitrogen gas, sealed, and placed in an oil bath heated to 200 ° C. for 20 minutes.

  After 20 minutes, the metal elution device was quickly transferred to a water bath and cooled until the temperature in the metal elution device reached 20 ° C. Subsequently, the entire amount of the liquid contained in the metal eluting device was collected in a beaker while washing the metal eluting device with pure water.

The collected liquid was subjected to suction filtration using a glass filter (2G4, manufactured by SHIBATA) to separate the residue and the filtrate (first filtrate).
The residue on the glass filter was further washed with suction filtration using 100 ml of pure water, and the filtrate (second filtrate) was recovered.

  The first filtrate and the second filtrate were mixed and filtered through a membrane filter having a pore size of 0.5 μm. The obtained filtrate was subjected to metal analysis by ICP emission method, and the elution amount of Cd was measured. Table 1 shows the elution amount of Cd measured by metal analysis in terms of the elution amount (μg) per 1 g of the sample.

(Comparative Example 5)
Except that barley straw was used as the sample to be analyzed, metal analysis was performed in the same procedure as in Comparative Example 4, and the amount of Cd eluted was measured. The measurement results are shown in Table 2 in terms of the amount eluted per gram of sample.

(Comparative Example 6)
Except that eucalyptus was used for the sample to be analyzed, metal analysis was performed in the same procedure as in Comparative Example 4, and the amount of Cd eluted was measured. The measurement results are shown in Table 2 in terms of the amount eluted per gram of sample.

なお、表中の数字の単位はμｇ／ｇである。 [Table 1]

The unit of the numbers in the table is μg / g.

[Table 2]

As can be seen from Table 1 and Table 2, the metal elution method of the present invention can elute a much larger amount of metal into water than the conventional metal elution method.
Although the present invention has been described above, the present invention is not limited to the embodiments, and various modifications can be made.

FIG. 1 is a diagram showing the steps of a metal elution method. FIG. 2 is a schematic view showing the entire metal elution apparatus for performing the metal elution method according to the present embodiment. FIG. 3 is a schematic view showing a cross section of the above-described metal eluting device, which is a portion for performing metal elution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... High pressure pump 2 ... Heater 3 ... Metal eluting device 31 ... Main-body part 32 ... 1st joint member 33 ... 2nd joint member 34 ... Filter 35 ... Auxiliary filter 4 ... Cooler 5 ... Back pressure valve 6 ... Storage tank 7 ... Receiving container

Claims (5)

A metal elution method for eluting a metal contained in a sample into pressurized hot water, wherein the metal is eluted by bringing the sample into contact with pressurized hot water while being dispersed in the pressurized hot water. A contact step and a second contact step of eluting the metal by further contacting the sample captured by the filter with pressurized hot water ,
The first contact step and the second contact step are performed in a state in which pressurized hot water is constantly flowed,
The metal elution method , wherein the pressurized hot water is pressurized at 10 MPa or less and heated in a range of 120 to 200 ° C.   The metal elution method according to claim 1, wherein an acid is added before the pressurized hot water containing the eluted metal is subjected to metal analysis. The metal elution method according to claim 1 or 2, wherein the sample is in a powder form having a particle size of 50 to 800 µm. A metal analysis method, wherein the metal elution method according to any one of claims 1 to 3 is performed as a pretreatment, and the resulting treatment solution from which the metal has been eluted is analyzed. It is a metal elution apparatus with which the metal elution method as described in any one of Claims 1-3 is performed,
A metal eluting device for eluting the metal contained in the sample into pressurized hot water ;
A high-pressure pump for compressing and transferring water for eluting the metal contained in the sample;
A heater for heating water compressed and transferred by the high-pressure pump;
A cooler for cooling the treatment liquid flowing out from the outlet of the metal eluting device;
A filtration device for removing fine particles from the treatment liquid cooled by the cooler;
Equipped with a,
The metal eluting device has a main body in which the sample is sealed ,
An inlet part through which the main body part flows the pressurized hot water into the main body part;
A first joint member removable at the entrance,
An outlet for allowing the pressurized hot water to flow out of the main body,
A detachable second joint member at the outlet,
A filter attached to the outlet and capturing the sample;
I have a,
The metal elution apparatus , wherein the filter attached between the outlet portion and the second joint member is replaceable .

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