KR102113144B1 - Purification treatment agents and purification treatment methods - Google Patents

Abstract

Provided is a purification treatment agent and a purification treatment method capable of simultaneously removing cadmium and fluorine contained in contaminated water or contaminated soil.
The purification treatment agent simultaneously removes cadmium and fluorine from contaminated water or contaminated soil containing at least cadmium and fluorine, and contains a metal powder containing iron or an iron alloy and a compound containing an alkali salt of a carboxyl group or a carboxyl group. The purification treatment method is a method of simultaneously removing cadmium and fluorine from contaminated water or contaminated soil containing at least cadmium and fluorine, and includes a step of bringing the purification treatment agent into contact with contaminated water or contaminated soil.

Description

Purification treatment agent and purification treatment method {PURIFICATION TREATMENT AGENTS AND PURIFICATION TREATMENT METHODS}

The present invention relates to a purification treatment agent and a purification treatment method.

It is known that heavy metals such as arsenic, selenium, lead, cadmium and chromium, and contaminants such as fluorine are harmful to the human body and cause health disorders. For this reason, environmental pollution by these pollutants has become a problem in recent years. Heavy metals are included in groundwater, river water, lake water, and various industrial drainage, and environmental standards and drainage standards are established. Therefore, when the content of heavy metals in water exceeds these standards, it is necessary to perform a process of removing heavy metals from water.

Among these pollutants, a method for continuously purifying water and soil contaminated with fluorine (hereinafter also referred to as "contaminated water" and "contaminated soil") is a method of adsorbing and removing contaminants using an adsorbent. Is proposed. This adsorption method is a method in which contaminants containing contaminants are continuously passed through an adsorption tower filled with an adsorbent, and contaminants are adsorbed and removed by contacting the contaminants with the adsorbents.

As the adsorbent used in this method, activated carbon, activated alumina, zeolite, titanium acid and zirconia hydrate are known. In the adsorption method, it is possible to achieve excellent removal efficiency by selecting the type of these adsorbents according to the type of contaminants to be purified. However, since these adsorbents are expensive, there is a problem that the cost in the purification treatment is increased.

On the other hand, as a method for purifying contaminated water, a method of adsorbing arsenic in water to iron powder is known, and various proposals have been made to improve the adsorption capacity of iron powder. Patent Document 1 describes an iron powder having a surface coated with an iron hydroxide as a arsenic purification treatment agent. In addition, Patent Documents 2 to 6 disclose iron powders containing a predetermined amount of sulfur or phosphorus. The anode reaction (Fe → Fe ²⁺ + 2e ⁻ ) of iron is promoted by the addition of sulfur or phosphorus. As a result, a reduction or insolubilization reaction of heavy metals such as cadmium and arsenic is promoted, and purification performance can be improved.

Japanese Patent Publication No. 2006-272260 Japanese Patent Publication No. 2006-312163 Japanese Patent Publication No. 2008-043921 Japanese Patent Publication No. 2009-082818 Japanese Patent No. 4755159 Japanese Patent No. 5046853

In Patent Documents 1 to 6, improvement of the ability to remove heavy metals by iron powder has been studied, but it is desired to further improve the adsorption efficiency of heavy metals. It has been found by the inventors' study that when iron alone was used, simultaneous removal of cadmium and fluorine may be difficult due to the concentration of heavy metals in water or the influence of trace components such as other compounds.

The present invention has been made in view of the above problems, and an object thereof is to provide a purification treatment agent and a purification treatment method capable of simultaneously removing cadmium and fluorine contained in contaminated water or contaminated soil.

Purification treatment agent according to the present invention, at the same time to remove cadmium and fluorine from contaminated water or contaminated soil containing at least cadmium and fluorine, a compound containing a metal component containing iron or an iron alloy and an alkali salt of a carboxyl group or a carboxyl group It contains.

In the said purification treatment agent, the said compound may contain at least 1 sort (s) selected from the group which consists of sodium oleate, potassium sodium tartrate, and sodium laurate.

In the purification treatment agent, the metal powder may be atomized powder.

In the purification treatment agent, the metal powder may contain sulfur.

In the said purification treatment agent, the sulfur content of the said metal powder may be 0.05 mass% or more and 5 mass% or less.

The purification treatment method according to the present invention is a method for simultaneously removing cadmium and fluorine from contaminated water or contaminated soil containing at least cadmium and fluorine. The purification treatment method includes a step of bringing the purification treatment agent according to the present invention into contact with the contaminated water or the contaminated soil.

In the purification treatment method, the pH of the eluate contained in the contaminated water or the contaminated soil at the time of initiation of contact between the contaminated water and the contaminated soil may be adjusted to a range of 2 or more and 6.5 or less. .

In the purification treatment method, the contaminated water or the contaminated soil may further contain at least one selected from the group consisting of arsenic, selenium, chromium, and lead.

According to the present invention, it is possible to provide a purification treatment agent and a purification treatment method capable of simultaneously removing cadmium and fluorine contained in contaminated water or contaminated soil.

Hereinafter, the purification treatment agent and purification treatment method according to the embodiment of the present invention will be described in detail.

(Purification treatment agent)

First, the purification treatment agent which concerns on this embodiment is demonstrated. The purification treatment agent which concerns on this embodiment removes cadmium and fluorine simultaneously from polluted water or polluted soil containing at least cadmium and fluorine. This purification treatment agent contains a metal powder containing iron or an iron alloy, and a compound containing a carboxyl group or an alkali salt of a carboxyl group (hereinafter also referred to as a carboxylic acid-based compound).

"Alkali salt of a carboxyl group" means a chemical structure in which H in a carboxyl group (R-COOH, R is a hydrocarbon group) is replaced by an alkali metal such as Na or K. Moreover, this purification treatment agent may further contain other components, such as a solvent and a pH adjuster, in the range which does not interfere with the effect of this invention besides a metal powder and a carboxylic acid compound.

The present inventors conducted a prudent study on a purification treatment agent that enables simultaneous removal of cadmium and fluorine contained in contaminated water or contaminated soil. As a result, the present inventors found out that by using a purification treatment agent containing a compound containing an alkali salt of a carboxyl group or a carboxyl group, a metal powder containing iron or an iron alloy can be simultaneously removed from cadmium and fluorine. , To the present invention.

The mechanism by which the cadmium and fluorine can be simultaneously removed by the purification treatment agent according to the present embodiment is not clear, but is estimated as follows. The carboxyl group and the alkali salt of the carboxyl group have high affinity for iron. Therefore, iron ions dissolved in the surface of the iron powder (or iron alloy powder) or in a liquid form a suitable form for simultaneous removal of cadmium and fluorine by the action of an alkali salt of a carboxyl group or a carboxyl group. By this, it is considered that simultaneous removal of cadmium and fluorine was made possible. Therefore, according to the purification treatment agent which concerns on this embodiment, simultaneous removal of cadmium and fluorine contained in contaminated water or contaminated soil becomes possible.

The said purification treatment agent is obtained by physically mixing a metal powder and a carboxylic acid compound. Hereinafter, each component included in the purification treatment agent will be described in detail.

<Metal powder>

The metal powder contains iron or an iron alloy, and has a function of removing heavy metals from contaminated water by adsorbing heavy metals such as cadmium. "Heavy metal" is a metal species having a specific gravity of 4.5 or more at 25 ° C. For example, cadmium exists in the state of cadmium ions (Cd ^{2 +} ) in contaminated water. According to the metal powder, this cadmium ion is reduced by electrons emitted by the iron anode reaction (Fe → Fe ^{2 +} + 2e ⁻ ), and metal cadmium is precipitated on the surface of the metal powder, thereby efficiently removing cadmium in the contaminated water. can do.

The metal powder is a powder containing iron as a main component and includes, for example, carbon, sulfur, nickel, copper, zinc, aluminum or cobalt as alloying elements other than iron. Here, the "main component" means a component (for example, 50% by mass or more) that is most contained on a mass basis of each component of the metal powder.

It is preferable that a metal powder contains sulfur especially among the said alloy elements. Thereby, the effect of removing heavy metals by metal powder can be improved. In addition, the mechanism by which the effect of removing heavy metals is improved by sulfur is estimated as follows.

Corrosion of iron increases with the addition of sulfur, and the anode reaction (Fe → Fe ^{2 +} + 2e ⁻ ) of iron on the surface of the metal powder is promoted. Thereby, iron ions (Fe ²⁺ ) are efficiently generated on the surface of the metal powder, and as a result, oxides and hydroxides of iron grow rapidly. As a result, it is considered that adsorption of heavy metals existing in the state of metal ions or compound ions in polluted water or contaminated soil is promoted, and removal of heavy metals is efficiently performed.

The sulfur content of the metal powder is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. When the sulfur content exceeds 5% by mass, the efficiency of adsorption of heavy metals by metal powder is lowered, and there is a concern that the cost of the purification treatment agent is unnecessarily increased. For this reason, it is preferable that the upper limit of sulfur content is 5 mass% or less.

On the other hand, the sulfur content of the metal powder is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.8% by mass or more. When the sulfur content is less than 0.05% by mass, the effect of removing the heavy metals may be insufficient. For this reason, it is preferable that the lower limit of the sulfur content is 0.05% by mass or more. In addition, the sulfur content of a metal powder is a value measured using the carbon-sulfur analyzer by a combustion method.

The metal powder is not particularly limited as long as it is iron-based powder, and various metal powders industrially available can be used. For example, as the metal powder, iron-based full metal powder (prealloy alloy powder) or partial metal powder (premix alloy powder) such as atomized iron powder, cast iron powder, and sponge iron powder can be used.

The metal powder is particularly preferably a metal powder (atomized powder) produced by the suatomizing method. Atomized powder can be mass-produced. For this reason, by using atomized powder as a metal powder, mass production of a purification treatment agent is possible, and it can be used for large-scale processing in a processing facility or the like. In addition, there is also an advantage that the atomized powder can have a uniform component and particle size. The atomized powder may be a complete metal powder obtained by atomizing the iron alloy or a partially alloyed powder obtained by attaching the metal powder after atomizing the iron powder.

The average pore diameter of the metal powder is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 100 μm or less. When the average pore diameter of the metal powder exceeds 1000 µm, the surface area of the metal powder becomes small, and there is a fear that the removal rate of heavy metals may decrease. For this reason, it is preferable that the upper limit of the average hole diameter of a metal powder is 1000 micrometers or less.

On the other hand, the average pore diameter of the metal powder is preferably 1 µm or more. When the average pore diameter of the metal powder is less than 1 µm, there is a concern that the yield at the time of manufacturing the metal powder is lowered and the handleability of the metal powder is lowered. For this reason, it is preferable that the lower limit of the average pore diameter of the metal powder is 1 µm or more.

Here, the "average hole diameter" of the metal powder is determined by a dry sieve classification test using a sieve specified in JIS-Z-8801 (2006), and the particle diameter distribution is determined, and the cumulative mass in the particle diameter distribution is 50%. Say the particle size.

<Carboxylic acid compound>

The carboxylic acid-based compound is not particularly limited as long as it has affinity for iron and can hold iron in a form suitable for simultaneous removal of cadmium and fluorine. The carboxylic acid-based compound contains at least one selected from the group consisting of sodium oleate, potassium sodium tartrate and sodium laurate. Since these compounds containing an alkali salt of a carboxyl group have water solubility, they are suitable for forming an iron surface or an iron ion in a form suitable for simultaneous removal of cadmium and fluorine. In particular, it is preferable to use sodium oleate, and more preferably to use sodium laurate.

By using these carboxylic acid compounds, the effect of simultaneous removal of cadmium and fluorine is obtained while suppressing cost. In addition, the compounds listed above are examples, and the same effect is expected even when other compounds containing carboxyl groups or alkali salts of carboxyl groups are used.

<Contaminated water, contaminated soil>

The contaminated water and contaminated soil to be treated with the purification treatment agent include at least cadmium and fluorine, and may also contain other heavy metals such as arsenic, selenium, chromium, and lead, and these heavy metal compounds.

The contaminated soil contains moisture (chemical water, moisture absorbing water, capillary water, gravity water, rain water, etc.), and heavy metals and fluorine are eluted (eluate). Therefore, the heavy metals and fluorine contained in the contaminated soil can be removed by treating the eluate with a purification treatment agent like contaminated water.

When the contaminated soil does not contain moisture, the eluate can be obtained by adding water to the contaminated soil to elute heavy metals and fluorine. In addition, heavy metals and fluorine contained in the contaminated soil may be removed by passing a solution such as water containing the purification treatment agent through the contaminated soil.

Heavy metals or heavy metal compounds exist as heavy metal ions or heavy metal compound ions in contaminated water or contaminated soil, and are dissolved in contaminated water or contaminated soil. Among these heavy metals or heavy metal compounds, particularly those which are desired to be removed are cadmium, arsenic, selenium, chromium and lead.

Examples of the heavy metal compound include cadmium nitrate, sodium arsenate, sodium selenite, and potassium dichromate. Examples of heavy metal ions or heavy metal compound ion, e.g., cadmium ion (Cd ^{2 +),} a non-dissipative ion (AsO ₄ ^{3 -),} selenium acid ion (SeO ₄ ^{2 -),} Pb (Pb ^{2 +),} chromium ion ( Cr ^{+ 6,} and the like). Hereinafter, an estimation mechanism in which heavy metals and fluorine are adsorbed to the metal powder of the purification treatment agent will be described.

Cadmium and selenium are dissolved in water in the state of cadmium ions (Cd ^{2 +} ) and selenic acid ions (SeO ₄ ^{2 −} ), respectively. According to the purification treatment agent, since the anode reaction of iron on the surface of the metal powder is promoted, cadmium ions and selenium ions can be efficiently reduced. Accordingly, metal cadmium and metal selenium can be deposited on the surface of the metal powder, and cadmium and selenium can be efficiently removed from contaminated water or contaminated soil.

Arsenic, non-ionic dispersion (AsO ₄ ^{3 -)} and is dissolved in water in the state of, it is possible to remove by creating a water-insoluble compound by reaction with iron ions. In addition, iron ions can be efficiently released into water by using a non-metallic reducing agent and a metal powder. That is, by reacting non-oxygen ions with iron ions, insoluble iron non-arsenate (a compound of non-arsenic acid and iron) is precipitated on the surface of the metal powder (by adsorbing heavy metals to the metal powder), thereby efficiently removing non-oxygen ions from the water. Can be. In addition, the reaction formula is expressed as 3Fe ^{2 +} + 2AsO ₄ ^{3 −} → Fe ₃ (AsO ₄ ) ₂ .

The hexavalent chromium ions (Cr ^{6 +} ) and lead ions (Pb ^{2 +} ) react with iron ions released as a metal component by the anode reaction of iron to form an iron compound. Thereby, chromium ions and lead ions can be deposited on the surface of the metal powder as water-insoluble compounds. As a result, chromium ions and lead ions can be efficiently removed from the water. In addition, since trivalent chromium ion (Cr ³⁺ ) is less harmful to the human body, it is not subject to purification.

The mechanism by which fluorine in water is removed by metal powder is unclear. However, when the metal powder immersed in fluorine-containing contaminated water is analyzed using X-ray photoelectron spectroscopy (XPS), peaks of iron ions and fluorides are confirmed, so that the metal powder is in the state of iron fluoride. It is presumed to be adsorbed.

(Purification treatment method)

Next, the purification treatment method according to the present embodiment will be described. The purification treatment method according to the present embodiment is a method of simultaneously removing cadmium and fluorine from contaminated water or contaminated soil containing at least cadmium and fluorine, and is performed using the purification treatment agent according to the present embodiment. In addition, in this embodiment, the contaminated water or contaminated soil that is the object of the purification treatment further contains at least one heavy metal selected from the group consisting of arsenic, selenium, chromium, and lead, in addition to cadmium and fluorine. In the present embodiment, a case will be described in which contaminated water is subjected to purification treatment and cadmium and fluorine contained therein are simultaneously removed by the purification treatment agent.

In the purification treatment method according to the present embodiment, a step of bringing the purification treatment agent into contact with contaminated water is performed. In this process, first, a purification treatment agent is filled in a predetermined container. Then, contaminated water is added to the container, followed by stirring. Thereby, cadmium, fluorine, and other heavy metals contained in the contaminated water are removed from the contaminated water by adsorbing on the surface of the metal powder.

The addition amount of the purification treatment agent is not particularly limited, but is preferably 0.1 g or more with respect to 1000 mL of contaminated water, and more preferably 0.2 g or more, based on the mass of the metal powder contained in the purification treatment agent. When the mass of the metal powder contained in the purification treatment agent is less than 0.1 g with respect to 1000 mL of contaminated water, there is a concern that the purification effect may fluctuate due to the fluctuation effect of removal of heavy metals by the metal powder. Therefore, the lower limit of the mass of the metal powder contained in the purification treatment agent is preferably 0.1 g / 1000 mL or more.

On the other hand, the addition amount of the purification treatment agent is preferably 100 g or less, and more preferably 10 g or less, with respect to 1000 mL of contaminated water based on the mass of the metal powder. Even if the mass of the metal powder contained in the purification treatment agent exceeds 100 g per 1000 mL of contaminated water, the effect of removing heavy metals tends to be saturated. Therefore, from the viewpoint of cost reduction, it is preferable that the upper limit of the mass of the metal powder contained in the purification treatment agent is 100 g / 1000 mL or less.

The stirring time of the contaminated water is preferably 72 hours or less, more preferably 36 hours or less. When the stirring time exceeds 72 hours, the increase in the amount of cadmium and fluorine removal with respect to the stirring time decreases, and the removal efficiency decreases. For this reason, it is preferable that the upper limit of stirring time is 72 hours or less.

On the other hand, the stirring time is preferably 10 minutes or longer, and more preferably 30 minutes or longer. When the stirring time is less than 10 minutes, there is a fear that it is difficult to sufficiently remove cadmium and fluorine contained in the contaminated water. For this reason, it is preferable that the lower limit of the stirring time is 10 minutes or more.

The pH of the contaminated water at the start of contact between the purification treatment agent and the contaminated water (hereinafter also referred to as the starting pH) is preferably adjusted to 2 or more, more preferably adjusted to 3 or more, and adjusted to 4.5 or more It is more preferable. When the starting pH of the contaminated water is less than 2, hydrogen is likely to be generated, and there is a fear that the effect of removing heavy metals by the metal powder is lowered. For this reason, it is preferable that the lower limit of the starting pH is 2 or more.

On the other hand, the starting pH is preferably 6.5 or less, more preferably 6 or less, and even more preferably 5 or less. When the starting pH exceeds 6.5, there is a fear that the effect of removing fluorine by the metal powder is lowered. For this reason, it is preferable that the upper limit of the starting pH is 6.5 or less.

The pH of the contaminated water can be adjusted by, for example, adjusting the addition amount of the non-metallic reducing agent, and adding a solvent such as water or a pH adjusting agent before starting the contact of the purification treatment agent. Examples of the pH adjusting agent include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid or organic acids such as formic acid, acetic acid or oxalic acid.

In addition, in the said embodiment, although the case where the purification treatment agent is filled in a container and thereafter adding contaminated water and stirring was demonstrated, it is not limited to this. For example, a method in which contaminated water is continuously passed through a column filled with a purification treatment agent may be employed.

In addition, in the above-described embodiment, only the purification treatment of contaminated water has been described, but the purification treatment of contaminated soil can also be performed as follows. First, an eluate containing heavy metals and fluorine is prepared by eluting cadmium and fluorine and other heavy metals (arsenic, selenium, chromium and lead) from contaminated soil. Then, by treating the eluate in the same manner as the contaminated water in the above embodiment, cadmium, fluorine and other heavy metals contained in the liquid are removed. In this way, cadmium and fluorine contained in contaminated soil can be simultaneously removed, and other heavy metals can be removed.

Example

Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited by the following examples, but it is also possible to implement it by appropriately changing it within a range that can be suitable for the purpose described below, and all of them are included in the technical scope of the present invention.

(Example 1)

First, a container made of polyethylene having an inner volume of 500 mL was prepared, and 250 mL of mine wastewater was added to the container as contaminated water. This mine wastewater was collected from the area where groundwater contamination was observed in Korea, with a cadmium concentration of 0.07 mg / L, a fluoride ion concentration of 2 mg / L, and a lead concentration of 0.3 mg / L.

Next, a purification agent containing metal powder and sodium oleate was added to the contaminated water. As the metal powder, environmental iron powder containing 1% by mass of sulfur (Ecomel (registered trademark) 53NJ, manufactured by Kobe Seikosho Co., Ltd.) was used. In addition, so that the solid-liquid ratio (g / mL) was about 1: 100, the amount of metal powder added was 2.5 g, and the amount of sodium oleate added was 0.25 g. The solid-liquid ratio (g / mL) is the ratio of the total solid amount (g) to the total liquid amount (mL) in a mixture of contaminated water and a purification treatment agent.

Next, the pH and the redox potential (unit mV, ORP; Oxidation Reduction Potential) of the mixture of the contaminated water and the purification treatment agent were measured, respectively ("pre-test pH" and "pre-test ORP" in Table 2 below). In addition, the pH of the mixture was adjusted using hydrochloric acid.

For pH measurement, a pH meter (main body type = D-52, pH electrode type = 9615S) manufactured by Horiba Seisakusho Co., Ltd. was used. For the ORP measurement, an ORP system manufactured by Horiba Seisakusho (body type = D-52, ORP electrode type = 9300) was used. First, the electrode was immersed in the measurement solution, and waited until the values of pH and ORP became stable. And after stabilizing until the numerical value did not change, the numerical value was recorded as a measured value.

Next, using a horizontal shaker, the mixture of contaminated water and the purification treatment agent was shaken for 1 hour and stirred. At this time, the temperature was set to 25 ° C, a rotation speed of 140 rpm, and a shaking width of 4 cm.

After shaking, the pH and the redox potential of the mixture were measured respectively ("pH after test" and "after test ORP" in Table 2 below). Then, the mixed solution was suction filtered using a membrane filter having a pore diameter of 0.45 µm. Then, the concentrations of cadmium, fluorine, and lead remaining in the contaminated water were measured by the analytical methods described in 55.3, 34.4, and 54.3 of JIS-K0102 (2013). The experimental conditions and results are shown in Tables 1 and 2 below.

(Example 2)

It is the same as that of Example 1 except that the purification treatment agent containing potassium tartrate is used, and the pH and ORP conditions before the test are used.

(Example 3)

Example 1 and the above, except that the amount of the metal powder added was 0.25 g, the purification treatment agent containing sodium laurate was used, the liquid-liquid ratio was set to about 1: 500, and the pH and ORP conditions before the test were used. same.

(Comparative Example 1)

It is the same as Example 1 except that sodium thiosulfate (0.05 g) was used instead of sodium oleate, and pH and ORP conditions before the test were used.

(Comparative Example 2)

It is the same as that of the comparative example 1 except the conditions of pH and ORP before the test.

(Comparative Example 3)

It is the same as that of the comparative example 1 except the conditions of pH and ORP before the test.

(Comparative Example 4)

It is the same as that of Comparative Example 1 except that the amount of sodium thiosulfate added is 0.25 g, and the pH and ORP conditions before the test.

(Comparative Example 5)

It is the same as that of Comparative Example 1 except that sodium thiosulfate was not added, treatment time was 72 hours, and pH and ORP conditions before the test were added.

(Comparative Example 6)

It is the same as that of Comparative Example 5 except that lead-free contaminated water was used, treatment time was set to 24 hours, and pH and ORP conditions before the test were used.

(Comparative Example 7)

It is the same as that of Comparative Example 6 except for the conditions of pH and ORP before the test.

(Comparative Example 8)

It is the same as that of the comparative example 7 except the conditions of pH and ORP before the test.

(Review)

From the above experimental results, it can be considered as follows.

As in Examples 1 and 2, by using a purification treatment agent containing a compound (sodium oleate, potassium tartrate) containing an alkali salt of a carboxyl group, the cadmium concentration, fluorine concentration and lead concentration were all lower than the environmental reference values (cadmium Environmental reference value of concentration: 0.003 mg / L or less, Environmental reference value of fluorine concentration: 0.8 mg / L or less, Environmental reference value of lead concentration: 0.01 mg / L or less). Further, as in Example 3, even when a purification treatment agent containing sodium laurate was used, the cadmium concentration and the fluorine concentration were similarly below the environmental reference values.

In contrast, in both cases where sodium thiosulfate was added (Comparative Examples 1 to 4), and when a purification treatment agent containing only metal powder was added (Comparative Examples 5 to 8), both the cadmium concentration and the fluorine concentration were environmental. It did not result in below the reference value (it was difficult to remove cadmium and fluorine simultaneously). From these results, it was found that the use of a purification treatment agent containing sodium oleate, potassium sodium tartrate or sodium laurate effectively contributes to the simultaneous removal of cadmium and fluorine from contaminated water.

Moreover, in contrast to Examples 1 and 2, the effect of removing fluorine was greater in the case of using sodium oleate than in the case of using sodium tartrate. Moreover, in contrast to Examples 1 and 3, the removal effect of either cadmium or fluorine was greater in the case of using sodium laurate than in the case of using sodium oleate.

It should be understood that the embodiments and examples disclosed herein are examples in all respects, and are not limitative. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all changes within the meaning and scope of the claims and equivalents.

Claims (8)

A purification agent that simultaneously removes cadmium and fluorine from contaminated water or contaminated soil containing at least cadmium and fluorine,
Metal powder containing iron or iron alloy,
A purification treatment agent comprising a compound containing a carboxyl group or an alkali salt of a carboxyl group. The purification treatment agent according to claim 1, wherein the compound contains at least one selected from the group consisting of sodium oleate, potassium tartrate, and sodium laurate. The purification treatment agent according to claim 1 or 2, wherein the metal powder is atomized powder. The purification treatment agent according to claim 1 or 2, wherein the metal powder contains sulfur. The purification treatment agent according to claim 4, wherein the sulfur content of the metal powder is 0.05% by mass or more and 5% by mass or less. A purification treatment method that simultaneously removes cadmium and fluorine from contaminated water or contaminated soil containing at least cadmium and fluorine,
A purification treatment method comprising the step of bringing the purification treatment agent according to claim 1 or 2 into contact with said contaminated water or said contaminated soil. The method according to claim 6, wherein the pH of the eluate contained in the contaminated water or the contaminated soil is adjusted to a range of 2 or more and 6.5 or less at the time of initiating contact between the purification treatment agent and the contaminated water or the contaminated soil. Purification treatment method. The method according to claim 6, wherein the contaminated water or the contaminated soil further contains at least one selected from the group consisting of arsenic, selenium, chromium, and lead.