JP5870717B2 - Method for analyzing asbestos in gypsum, method for analyzing asbestos and heavy metals - Google Patents

Description

The present invention relates to how to analyze asbestos contained like gypsum board, heavy metals.

  Most of the waste gypsum board that is discharged with the dismantling of buildings has been disposed of in landfills, which is a concern for the tightness of managed disposal sites. Therefore, it is desirable to promote recycling. However, because there is a product manufactured in the past with asbestos in gypsum board, and there are cases where arsenic and cadmium are eluted from some waste gypsum board exceeding the standard, it is recycled. Therefore, it is necessary to make sure that the waste gypsum board does not contain asbestos, arsenic or cadmium.

  As a method for confirming the presence or absence of asbestos in the gypsum board, there is JIS A1481 “Measurement method of asbestos content in building material products” (hereinafter referred to as JIS method). The JIS method is widely used for general building material products, and is excellent in versatility. However, because the sample pretreatment method is complicated and requires specialized knowledge, the inspection cost is high and the scale is small. It is difficult to apply to waste gypsum board discharged at the demolition site.

  Several simple determination methods have been proposed in light of the problems of the JIS method. For example, a method for determining the presence or absence of asbestos by elution of Fe and Mg in asbestos using a solution and adding a color reagent to determine the presence or absence of asbestos has been developed (for example, a patent) (Refer literature 1 and nonpatent literature 1). Furthermore, although a simple detection kit for determining the presence or absence of asbestos using an asbestos-binding protein has been developed (see, for example, Non-Patent Document 2), these methods have difficulty in quantitative analysis of asbestos.

  In order to solve the above problems, the present applicant has developed an asbestos analysis method and an analytical sample preparation method capable of measuring the asbestos content contained in the gypsum board accurately, inexpensively and in a short time. Yes (see, for example, Patent Document 2).

JP 2008-26269 A JP 2010-122017 A

http://www.unichemy.co.jp/pdf_selectline/4-2catalog.pdf http://www.siliconbio.co.jp/41/50.html

  The asbestos analysis method described in Patent Document 2 is an excellent method capable of removing gypsum particles that interfere with the introduction of a simple chemical pretreatment and measuring the asbestos particles in a concentrated state. Needless to say, it is preferable to be able to perform measurement more inexpensively and more accurately. Furthermore, it would be very convenient if the content of harmful metals contained in the waste gypsum board could be measured at the same time.

The present invention, asbestos contained in the gypsum material consisting mainly of gypsum accurately, inexpensively also provide analyzable asbestos analytical methods in a short time as the first object, as a main component gypsum plaster asbestos and arsenic contained in the body, a heavy metal such as cadmium accurately, shall be the provision of low cost also a method of analyzing in a short time the second object.

  Since calcium sulfate, the main component of gypsum board, is hardly soluble in water, it is difficult to measure traces of asbestos and metals as it is. Therefore, in the previous invention (Japanese Patent Laid-Open No. 2010-122017), a method for easily and accurately quantifying asbestos was established by dissolving all gypsum components in a water-soluble test solution. The present invention is a further improvement of the invention described in Japanese Patent Application Laid-Open No. 2010-122017. A method for dissolving calcium sulfate in one step has been found, and the present invention has been completed. The present invention is as follows.

The present invention provides a method for analyzing the asbestos contained in the gypsum material consisting mainly of gypsum, a dissolution step of dissolving the gypsum which is a sample to be analyzed in an aqueous solution of ammonium formate, obtained by the dissolving step and a filtration step of filtering the aqueous solution, a drying step of drying the solid obtained in the filtration step, and analyzing the sample solids obtained in the drying step, seen containing asbestos analysis measuring the asbestos content, the The asbestos in the gypsum body is characterized in that the dissolution step completely dissolves the gypsum which is the main component of the gypsum body only with the aqueous solution of ammonium formate, without newly forming a salt insoluble in water. It is an analysis method.

  The present invention also includes a heavy metal analysis step of measuring the heavy metal content using the filtrate obtained in the filtration step as an analysis sample in addition to the analysis of asbestos in the gypsum body. It is a method for analyzing asbestos and heavy metals.

By using the method for analyzing asbestos in a gypsum body according to the present invention, asbestos contained in a gypsum body containing gypsum as a main component , such as a gypsum board, can be analyzed accurately, inexpensively and in a short time. In the use of the asbestos and heavy metals analysis methods plaster body in the present invention, such as gypsum boards, asbestos and arsenic contained in the gypsum material consisting mainly of gypsum, the accurately heavy metals such as cadmium, inexpensive Moreover, it can be analyzed in a short time .

It is a flowchart which shows the procedure of the asbestos analysis method and analysis sample preparation method as one Embodiment of this invention. It is an X-ray diffraction chart of the example of the present invention.

  The method for analyzing asbestos in gypsum according to the present invention separates asbestos from gypsum by dissolving calcium sulfate, which is the main component of gypsum like gypsum board, in an aqueous solution of ammonium formate, and analyzes this. It is characterized by that. The specific procedure is shown below.

  FIG. 1 is a flowchart showing a procedure of an analysis method for asbestos contained in a gypsum board and an analysis sample preparation method as an embodiment of the present invention. In addition, the analysis method of heavy metals contained in the gypsum board is also described in this.

  As a first step, an aqueous ammonium formate solution is added to gypsum board as an analysis target sample to dissolve calcium sulfate as a main component of gypsum board (dissolution process). In order to promote dissolution, it is preferable to grind the gypsum board and stir and mix the aqueous ammonium formate solution containing the gypsum board. The concentration of the ammonium formate aqueous solution used here and the amount added to the gypsum board are set so that calcium sulfate, which is the main component of the gypsum board, is completely dissolved. For example, calcium sulfate can be completely dissolved by adding 10 mL of a 2.0 mol / L ammonium formate aqueous solution to 0.1 g of gypsum board and stirring and mixing.

  The drug that dissolves calcium sulfate, the main component of gypsum board, includes ammonium formate aqueous solution, sodium formate, sodium acetate, ammonium acetate, sodium citrate, aqueous solution of EDTA (ethylenediaminetetraacetic acid) sodium, and the above drugs. An aqueous solution containing two or more types can be used. These drugs are highly soluble in gypsum and allow measurement of heavy metals in solution and have no effect on asbestos. Further, no salt precipitates after the calcium sulfate is dissolved.

Table 1 shows the residual ratio when calcium sulfate was dissolved using each drug. Since calcium sulfate interferes with asbestos analysis by X-ray diffraction, it is better that the residue rate is as low as possible. The residue rate shown in Table 1 was determined in the following manner. 20 mL of an aqueous solution adjusted to each concentration is added to 0.3 g of calcium sulfate reagent (CaSO ₄ .2H ₂ O) and dispersed with an ultrasonic cleaner for about 10 minutes, and then a fluororesin binder glass fiber filter paper (ADVANTEC PG- 60), and the amount of calcium sulfate residue after drying the filter paper was measured.

  In the aqueous solution of ammonium formate, the solution became transparent during dispersion by ultrasonic waves, and the filter paper after filtration became almost colorless. As shown in Table 1, the calcium sulfate residue rate was 0%. In the JIS method, when the secondary analysis sample is prepared, the standard of the residue rate is 15%. Compared with this, it can be seen that the above-mentioned drug can be used sufficiently as a drug for dissolving gypsum.

  As a second step, the aqueous solution obtained in the first step is filtered to separate the solids (filtration process). As the filter medium, a fluororesin binder glass fiber filter used in the method for preparing a secondary analysis sample of the JIS method can be used. The filtration method can be suction filtration as in the JIS method.

  As a third step, the solid content obtained in the second step is dried (drying process) to obtain an analysis sample. Drying may be performed in the same manner as drying for general water removal.

  As described above, the asbestos analysis sample can be obtained from the first step to the third step. The analytical sample thus obtained is free of gypsum that interferes with the measurement and concentrated asbestos. Therefore, in the measurement of asbestos content using the X-ray diffraction method as the next step, a small amount of asbestos is obtained. Can also be detected.

  In the fourth step, the analysis sample obtained in the third step is analyzed with an X-ray diffractometer to measure the asbestos content (asbestos analysis step). Here, an X-ray diffraction quantitative analysis method based on a basal standard absorption correction method defined in the JIS method may be used.

  By using the asbestos analysis method and analytical sample preparation method according to the present invention to remove particles that interfere with the measurement, a small amount of asbestos can be efficiently detected. As shown in Examples below, by dispersing waste gypsum powder in an aqueous ammonium formate solution, calcium sulfate, which is the main component of gypsum, is dissolved, and the contained asbestos (chrysotile, amosite, crocidolite) is obtained by X-ray diffraction. Detection was possible at a level of 0.1% by weight. This method is much simpler than the JIS method and can be expected to have an accuracy equal to or higher than that of the JIS method. Therefore, this method is considered to be an effective method for reconfirmation of asbestos free at the site of waste gypsum board recycling.

  Furthermore, heavy metals contained in the gypsum board can be analyzed using the filtrate obtained in the second step (heavy metal analysis step). For the analysis, an ICP emission analysis method or an atomic absorption method can be used. Examples of heavy metals that can be analyzed here include arsenic, cadmium, chromium, lead, and manganese. By using this method as shown in the examples described later, heavy metals contained in the gypsum board can be analyzed with high accuracy.

Example 1 (Detection of asbestos in calcium sulfate)
As a simulated sample of gypsum board, 0.5 g of calcium sulfate (CaSO ₄ · 2H ₂ O) reagent is placed in a colorimetric tube, 30 mL of 2.0 mol / L ammonium formate aqueous solution is added, and the mixture is dispersed with an ultrasonic cleaner. Calcium was dissolved. Then, 0.5 mg of asbestos standard sample (chrysotile JAWE111) was added, filtered with 25 mmφ fluororesin binder glass fiber filter paper (ADVANTEC PG-60), and dried at 105 ° C. for 12 hours. did. JEOL JDX-3530 was used for the X-ray diffractometer. Moreover, it carried out similarly about the asbestos standard sample (Amosite JAWE211) and the asbestos standard sample (crocidolite JAWE311).

  The X-ray diffraction chart is shown in FIG. When a sample obtained by adding 0.1 wt% of chrysotile standard sample to calcium sulfate is analyzed by X-ray diffraction, the diffraction line peculiar to chrysotile cannot be detected because the diffraction line derived from calcium sulfate is strong. However, when ammonium formate was treated, calcium sulfate was removed and chrysotile was detected (FIG. 2-A). A sample to which a standard sample of amosite and crocidolite was added could also be detected by X-ray diffraction.

Example 2 (Detection of asbestos in waste gypsum powder)
The actual sample of the waste gypsum board was processed by a crusher by an intermediate processor in Hiroshima Prefecture and the particle size was 4 mm or less (hereinafter, waste gypsum powder). The experiment was performed in the same manner as in Example 1, using 0.2 g of waste gypsum powder and 0.2 mg of asbestos standard sample.

  When the waste gypsum powder was pretreated with an aqueous ammonium formate solution, it became a brownish and slightly turbid solution during dispersion by ultrasonic waves, and brown residue was collected on the filter paper. Filtration of waste gypsum powder took time because of the large amount of residue compared to the calcium sulfate of Example 1. The pH of the ammonium formate aqueous solution was pH 6.8 without changing before and after the waste gypsum powder was charged.

  When 0.1% by weight of the chrysotile standard sample was added, the peak of the waste gypsum powder was significantly reduced by the pretreatment with ammonium formate. However, since the added amount of the chrysotile standard sample was 0.2 mg, the diffraction line of chrysotile The diffraction line at 2θ24.4 ° was particularly weak. However, since there is no diffraction line derived from waste gypsum in the vicinity of the strong 2θ12.1 ° diffraction line of chrysotile, it was possible to determine the presence or absence of chrysotile from only this peak (FIG. 2-B). When the 2θ12.1 ° diffraction line of the chrysotile was confirmed, the chrysotile could be detected even at about 0.2 mg when analyzed in more detail by changing the measurement conditions of the X-ray diffraction.

  Also in the sample added with amosite or crocidolite standard, amosite or crocidolite could be detected at the 0.1 wt% level by 2θ10.5 and 10.6 ° diffraction lines as in chrysotile.

Example 3 (Type of waste gypsum board and X-ray diffraction pattern)
For the seven types of waste gypsum board, the difference in the X-ray diffraction diffraction line patterns depending on the type of gypsum board was compared using samples that were crushed in a mortar after removing the paper. As a result of pretreatment with seven kinds of waste gypsum board with ammonium formate, there is a kind in which a gentle peak appears at 2θ12-13 ° near the 2θ12.1 ° diffraction line of chrysotile even when no asbestos standard product is added. I understood. Then, as a result of changing and analyzing the X-ray diffraction conditions, it was confirmed that it could be distinguished from chrysotile. The other diffraction lines of asbestos were not disturbed by those derived from waste gypsum powder residues.

Example 4 (Analysis of heavy metals in calcium sulfate)
Using calcium sulfate reagent as simulated samples of the gypsum board, asbestos standard sample (chrysotile JAWE111) in calcium sulfate reagent _(CaSO 4 · _2H 2 O) was mixed with 0.1 wt% equivalent, this 2.0 mol / L 10 mL of an aqueous solution of ammonium formate was added and dispersed with an ultrasonic cleaner to dissolve calcium sulfate. Reagents were added to this solution to prepare a heavy metal concentration of 0.1 mg / L. Then, it filtered with the fluororesin binder glass fiber filter paper (ADVANTEC PG-60), and obtained the filtrate. The filtrate was measured by ICP emission spectrometry. At this time, in order to eliminate errors in measurement values due to the presence of high concentrations of formate, ammonium, calcium, and sulfate ions, the component matrix of the standard solution for heavy metals is prepared to the same concentration as the test solution. A standard curve was used.

Table 2 shows the recovery rate (%) of heavy metals. As shown in Table 2, heavy metals could be measured with an accuracy close to 100%.

Claims (2)

A method of analyzing asbestos contained the gypsum to plaster composed mainly,
A dissolution step of dissolving a gypsum body as an analysis target sample with an aqueous solution of ammonium formate;
A filtration step of filtering the aqueous solution obtained in the dissolution step;
A drying step of drying the solid content obtained in the filtration step;
The solids obtained in the drying step and the analytical sample, see containing asbestos analysis measuring the asbestos content, a,
Analyzing the asbestos in the gypsum body, wherein the dissolution step completely dissolves the gypsum which is the main component of the gypsum body without generating a new salt insoluble in water only with the aqueous solution of ammonium formate. Method. In addition to the analysis of asbestos in the gypsum body according to claim 1 ,
Further, a method for analyzing asbestos and heavy metals in a gypsum body comprising a heavy metal analysis step of measuring a heavy metal content using the filtrate obtained in the filtration step as an analysis sample.