JP2003334542A - Anion adsorbent, method for removing anion using the adsorbent, method for regenerating anion adsorbent, and method for recovering element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an anion adsorbent free of lead which has an adsorption capacity equivalent to that of a heavy metal anion adsorbent containing lead. <P>SOLUTION: The anion adsorbent contains an amorphous iron hydroxide precipitate obtained by adding an alkali into an iron ion solution or an amorphous coprecipitate obtained by adding an alkali into a solution containing at least two kinds of metal elements producing hydroxide precipitates at different pH values as a main component. Lead is excluded from the two metal elements. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anion adsorbent, and in particular, it has been considered difficult to remove anions such as molybdenum, chromium, antimony, selenium, arsenic and boron from waste liquor and fluorine ions. The present invention relates to an anion adsorbent capable of effectively adsorbing an anion species, an anion removal method using the same, an anion adsorbent regeneration method, and an element recovery method.

[0002]

2. Description of the Related Art In recent years, with the development of science and technology, a wide variety of chemical substances have been manufactured and used. Many of these substances have harmful effects on human health and the ecosystem. Therefore, in Japan, the water quality environmental standard was revised in March 1993, monitoring items were added, and molybdenum, antimony, nickel, etc. were newly designated as heavy metals.

There has been no practical method for removing heavy metal anions containing chromium, selenium, arsenic, etc., such as molybdenum, antimony, etc., from a waste liquid.
The inventors of the present invention filed Japanese Patent Application No. 2000-93228 previously filed.
Japanese Patent Application No. 2001-253955 and Japanese Patent Application No. 2001-253955 propose a practical adsorbent for heavy metal anions.

[0004]

[Patent Document 1] Japanese Patent Application No. 2000-
Although the heavy metal anion adsorbents proposed in Japanese Patent Application No. 93228 and Japanese Patent Application No. 2001-253955 have excellent adsorption ability, they contain lead elements which are unfavorable to the ecosystem. There has been a problem that if the lead element is dissolved in the treatment liquid, it may have an adverse effect on the environment.

Therefore, the present invention has been made by paying attention to the above-mentioned problems, and an anion adsorbent containing no lead element, which is an alternative to the above-mentioned anion adsorbent containing lead element, has been proposed. It is intended to be provided.

[0006]

In order to solve the above problems, the anion adsorbent of the present invention is an amorphous iron hydroxide-based precipitation product obtained by adding an alkali to an iron ion solution. , Or an anion adsorbent whose main component is an amorphous co-precipitate obtained by adding an alkali to a solution containing at least two kinds of metal elements that form a hydroxide precipitate at different hydrogen ion concentrations. hand,
The at least two kinds of metal elements are metal elements other than lead. Since these anion adsorbents do not contain lead, not only does lead elute, but they also have high adsorption capacity comparable to conventional anion adsorbents containing lead elements. Moreover, a highly practical anion adsorbent that can be reused can be obtained. Also,
By eluting the adsorbed anions, the elements contained in the anions can be efficiently recovered.

In the method for removing anions of the present invention, the anion adsorbent according to any one of claims 1 to 3 is brought into contact with a solution containing anions, and the anion adsorbent is contained in the solution. It is characterized by adsorbing the anions that are generated, and the anions in the solution can be easily removed.

The anion adsorbent of the present invention is preferably used for anions containing molybdenum, chromium, antimony, selenium, arsenic, and boron, which have been difficult to remove, and fluoride ions. It is not limited to ionic species.

In the method for regenerating an anion adsorbent of the present invention, the adsorbed anion is eluted by treating the anion adsorbent according to any one of claims 1 to 3 treated with an alkaline solution. By regenerating the anion adsorbent that has adsorbed anions in the alkaline solution, not only can it be used repeatedly as an anion adsorbent, but the elements contained in the anion can be efficiently used. Can be collected in a timely manner.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION (Example) In this example, first,
The manufacturing method of the anion adsorbent will be described in Manufacturing Method 1 to Manufacturing Method 5, and the method and the result of the anion removal test using the manufactured anion adsorbent will be described.

[0011] (Production Method 1: Anion adsorbent: Fe- method for producing a precipitate) iron FeCl ₃ · 6H ₂ O chloride, iron nitrate Fe (NO _{3) 3} · 9H
₂ O is dissolved in water so as to be 1 mol · dm ⁻³ , and the pH is adjusted to 3 with an aqueous NaOH solution while stirring.
The precipitate obtained by this operation is filtered, and the precipitate is dried in a constant temperature dryer at 60 ° C for 70 hours. The solid powder obtained by crushing the dried solidified precipitate in an agate mortar was used as an anion adsorbent in Experiment 1 described later. From the X-ray diffraction patterns of the respective anion adsorbents, it was confirmed that the precipitate obtained from iron chloride had a sodium chloride diffraction pattern, and the precipitate obtained from iron nitrate had a sodium nitrate diffraction pattern. No diffraction pattern could be detected for the iron element, and it was assumed that the iron hydroxide compound was in an amorphous state.

(Experiment 1: Selenate ion removal test using Fe-precipitate) A selenate ion adsorption experiment was conducted using the anion adsorbent prepared according to the above-mentioned production method.

The adsorption experiment was carried out by adding sodium selenate Na ₂ SeO ₄ to pure water in a beaker to obtain a selenium element concentration of 10 mg · d.
Anion adsorbent concentration of 1000 mg ・ dm ^{-3 at} m ^-3 (pH 6.3)
It adjusted so that it might become, and it stirred by using the stirring blade made from a fluororesin. 0.01 liter of the solution was sampled using a glass syringe every predetermined time.
This is a filter holder for vacuum filtration equipped with glass fiber filter paper (GF-75 manufactured by ADVANTEC) (K manufactured by ADVANTEC
The sample was poured into G-13A) and filtered. The filtrate is an inductively coupled plasma (ICP) emission spectroscopic analyzer (SPS3000 manufactured by Seiko Denshi Kogyo Co., Ltd., and the quantitative detection limits are 50 microgram / liter, 5 microgram / liter, and 50 microgram / liter for arsenic, molybdenum, antimony, and selenium, respectively. Liter, which is 50 micrograms / liter). A hydride generator (THG1200 manufactured by Seiko Instruments Inc.) was used for arsenic, antimony and selenium. The hydride generation device generates each element as a hydride by the reduction vaporization method and introduces the generated gas into the ICP emission spectroscopic analysis device, which enables highly sensitive analysis.

The results are shown in FIG. All the precipitates showed a removal rate of 99% or more, and decreased to a concentration below the selenium drainage standard value.

(Production Method 2: Anion Adsorbent: Production Method of Purified Precipitate of Fe) The anion adsorbent of Fe-precipitation prepared in Production Method 1 includes sodium salts of sodium nitrate and sodium chloride. This is confirmed by X-ray diffraction. Since it is possible that anions such as nitrate and chloride ions interfere with the adsorption of selenate, we attempted to remove sodium salts from the adsorbent. The anion adsorbent of Fe-precipitate obtained from the iron nitrate of Production Method 1 was suspended and washed in pure water at a concentration of 10,000 mgdm ⁻³ , and after 15 minutes, the adsorbent was recovered by filtration. The collected adsorbent was dried in a constant temperature dryer at 60 ° C for 70 hours. X of adsorbent after drying
From the line diffraction pattern, it was confirmed that sodium nitrate had been removed and that the Fe-precipitated purified product was amorphous.

(Experiment 2: Selenate ion removal test using Fe-precipitated product) An adsorption experiment was performed in the same manner as in Experiment 1 except that the selenium element concentration was 30 mg.dm ^-3 .

The results are shown in FIG. There was a clear difference in the adsorption capacity between the case where the adsorbent was not washed and the case where it was washed. When the adsorbent was not washed, the selenate ion removal rate after 60 minutes was 68.9%. On the other hand, it was found that the washed adsorbent (Fe-precipitated refined product) had a removal rate of 99.7% and maintained a high adsorption capacity even in a high-concentration selenate ion solution.

This is considered to be because the anion (nitrate ion), which had been a hindrance factor during the adsorption of the selenate ion, was removed by washing the sodium salt in the adsorbent, which was the generation source.

(Experiment 3: pH dependence test of selenate ion adsorption on Fe-precipitate) The pH of the selenate ion solution was adjusted to a predetermined pH by adding sodium hydroxide and hydrochloric acid, and Fe-precipitate was added. The pH dependence of the adsorption of selenate ions onto selenium was investigated. In the experiment, the Fe-precipitated purified product obtained in Production method 2 was added to an aqueous solution having an elemental selenium concentration of 10 mg · dm ⁻³ so as to be 1,000 mg · dm ⁻³ . For comparison, an experiment was also performed using commercially available reagents iron hydroxide (FeO (OH), ferric oxyhydroxide). An experiment was conducted in the same manner as in Experiment 1 except that the adsorption amount after suspending the anion adsorbent for 2 hours was examined.

The results are shown in FIG. The adsorbent (Fe-precipitated purified product) after the washing treatment showed the maximum adsorption amount at pH 3, and the unit adsorption amount was 0.063 kg · kg ⁻¹ . On the other hand, p
The amount of selenate ion adsorbed decreased with the increase of H.
This, OH ^- ions are amorphous at a adsorbent surface by increasing [Fe (OH) _2] ⁺ or [Fe (OH)] ²⁺ is, OH ^- was crystallized by binding to This is probably because Fe (OH) ₃ was generated and the number of adsorption sites was reduced. This can be inferred from the fact that the crystallized reagent iron hydroxide (FeO (OH)) showed almost no adsorptivity for selenate ions.

(Experiment 4: Repeated adsorption / desorption test of selenate ion by Fe-precipitate) FIG. 3 shows that adsorption and desorption of anions by anion adsorbent can be controlled by controlling the pH of the solution. There is. That is, the anion adsorbent that has adsorbed the anions is filtered off, washed with an alkaline aqueous solution to desorb the anions, and the anion desorbed adsorbent is further filtered and dried to obtain the anion adsorbent. Can be played. By repeating regeneration, it is possible to minimize the amount of waste sludge brought to the final disposal site. It is also possible to recover valuable metals such as selenium, antimony and molybdenum from the desorbed anions.

In order to confirm this, the pH of the same solution
Was repeatedly changed from 3 to 11, and the adsorption / desorption behavior of selenate ion was investigated. The experiment was conducted with a selenium element concentration of 10 mg.dm
^-3 solution containing 1000 Fe-precipitated purified product prepared in Production method 2
The pH was adjusted by using hydrochloric acid and sodium hydroxide in addition to mg · dm ⁻³ . Holding at pH 3 for 1 hour and at pH 11 for 1 hour was repeated.

The results are shown in FIG. After adsorbing the selenate ion at pH 3, it was found that the selenate ion was eluted when the pH was adjusted to 11, and the eluted selenate ion was re-adsorbed when the pH was returned to 3 again. From this experiment, the removal rate of selenium was 98.6% or more, and the elution rate of selenate ion from the adsorbent was 94% or more. Further, no performance deterioration of the adsorbent due to repeated adsorption / desorption was observed.

(Experiment 5: Test for removing various anions by Fe-precipitate) A test for removing various anions by Fe-precipitate derived from iron chloride prepared in Production Method 1 was conducted. The anion species tested are summarized in Table 1. For comparison, the cation cadmium ion was also tested.

[Table 1]

In the adsorption experiment, the element concentration of various anions was 10
The pH of the aqueous solution of mg · dm ⁻³ was adjusted to pH 3, and then the Fe-precipitate derived from iron chloride prepared in Production method 1 was added so as to have a concentration of 1000 mg · dm ⁻³ .

The results of arsenite ion, pentachloroantimony ion ([SbCl ₅ ] ^- ), molybdate ion, dichromate ion, and cadmium ion are shown in FIG. It was revealed that this adsorbent exhibits adsorptivity to all anionic species. On the other hand, it was also revealed that this adsorbent showed almost no adsorptivity for the cation cadmium ion.

Although the removal rate of arsenite ions was a low value of 49.5%, it has been confirmed that the removal rate of 99% or more is shown near pH 6.

Further, fluorine ions (fluorine ion concentration
51.25mg ・ dm ^-3 ), sulfate ion (sulfate ion concentration 87.49mg
・ DM ^-3 ), chloride ion (chlorine ion concentration 30.60mg ・ d
m ^-3 ) mixed solution (pH 3.0) into the iron chloride-derived Fe of production method 1
-When the precipitate was added to give 5000 mg dm ^-3 ,
From the measurement results of liquid chromatography, after 5 minutes,
The removal rates were 86.3%, 100% and 49.4%, respectively.

(Production Method 3: Production Method of Anion Adsorbent: Fe-Cu Coprecipitate) First, 1 mol of copper chloride CuCl ₂ .2H ₂ O,
2 mol of iron chloride FeCl ₃ .6H ₂ O is dissolved in water and stirred for 30 minutes.

Then, NaOH is added until the pH of the whole solution becomes 7.
The solution was added, and the mixture was stirred again for 30 minutes, and the precipitate generated in the solution after the stirring was suction filtered to obtain a precipitate.

After filtering this precipitate, it was dried in a constant temperature dryer at 60 ° C. for 70 hours and pulverized in a mortar.
A Fe-Cu coprecipitate, which is an anion adsorbent used in Experiment 6 described later, could be obtained. From the X-ray diffraction pattern, it was confirmed that this coprecipitate was also amorphous.

(Experiment 6: Hazardous element removal test using Fe-Cu coprecipitate) Six kinds of harmful substances using an anion adsorbent (Fe-Cu coprecipitate) prepared based on the above-mentioned manufacturing method A removal test of elemental ions (arsenic, antimony, selenium, molybdenum, chromium, cadmium) was conducted.

The removal test was carried out in pure water such that the amount of the anionic adsorbent prepared by the above-mentioned manufacturing method was 3000 mg · dm ⁻³ , and the concentration of various harmful elements prepared by each method in Table 1 was changed. The experiment was carried out in the same manner as in Experiment 1 except that the pH was adjusted to 10 mg · dm ⁻³ and the pH was not adjusted.

Arsenic, antimony, selenium, molybdenum,
The results of the chromium and cadmium removal test are shown in FIG.

As a result of the test, among the elements of arsenic, antimony, selenium, molybdenum, chromium and cadmium used in the test, all elements except cadmium showed a high adsorption rate, and 1 hour after the start of the removal. The concentration of the remaining elements in the can be read from the graph,
The concentration decreased to 0.1 mg · dm ⁻³ or less, and the concentration of each harmful element decreased to below the wastewater standard value.

(Production Method 4: Production Method of Anion Adsorbent: Fe-Mg Coprecipitate) First, 1 mol of MgCl ₂ .6H ₂ at room temperature
And O, and which FeCl ₃ · 6H _{2 O} of 2mol was dissolved in water 3
Stir for 0 minutes.

Then, NaOH was added until the pH of the whole solution reached 9.
The solution was added, and the mixture was stirred again for 30 minutes, and the precipitate generated in the solution after the stirring was suction filtered to obtain a precipitate.

After filtering this precipitate, it was dried in a constant temperature dryer at 60 ° C. for 70 hours and ground in a mortar,
An Fe-Mg coprecipitate, which is an anion adsorbent used in Experiment 7 described later, could be obtained. From the X-ray diffraction pattern, it was confirmed that this coprecipitate was also amorphous.

(Experiment 7: Removal test of harmful elements using Fe-Mg coprecipitate) Next, using this anion adsorbent, 6 kinds of harmful element ions (arsenic, antimony, selenium,
An adsorption experiment for molybdenum, chromium and cadmium) was conducted in the same manner as in Experiment 6.

The results of the test are used in the test, as shown in FIG.
All 6 elements except cadmium
Shows a high adsorption rate, and 1 hour has passed since the start of removal
The concentration of remaining elements can be read from the graph.
0.1 mg · dm so that ^-3To the following concentrations
The concentration of each harmful element is lower than the standard value of wastewater.
Fell.

(Production Method 5: Production Method of Anion Adsorbent: Al-Mg Coprecipitate) First, 1 mol of MgCl ₂ .6H ₂ O at room temperature.
And 2mol of AlCl ₃ dissolved in it are mixed to 30
Stir for minutes.

Then, NaOH was added until the pH of the whole solution reached 9.
The solution was added, and the mixture was stirred again for 30 minutes, and the precipitate generated in the solution after the stirring was suction filtered to obtain a precipitate.

After filtering this precipitate, it was dried in a constant temperature drier at 60 ° C. for 70 hours, and pulverized in a mortar,
An Al-Mg coprecipitate, which is an anion adsorbent used in Experiment 8 described later, could be obtained. From the X-ray diffraction pattern, it was confirmed that this coprecipitate was also amorphous.

(Experiment 8: Removal test of harmful elements using Al-Mg coprecipitate) Next, using the anion adsorbent, adsorption of the four kinds of harmful element ions (selenium, molybdenum, chromium, cadmium) The experiment was performed in the same manner as the experiment 6.

As shown in FIG. 8, the result of the test shows that among the four elements used in the test, all the elements except cadmium show a high adsorption rate, and the remaining elements 1 hour after the start of the removal. As can be seen from the graph, the concentration of No. 1 was reduced to a concentration of about 0.1 mg · dm ⁻³ , and the concentration of each harmful element was reduced to a concentration below the wastewater standard value.

As shown in Experiments 1 to 8, the anion in the solution could be easily removed simply by adding the anion adsorbent of the present invention to the solution containing the anion.

(Mechanism of Anion Adsorption) Next, the mechanism of anion adsorption of the anion adsorbent used in each of Experiments 6 to 8 will be described.

The Fe-Cu coprecipitate which is the anion adsorbent used in Experiment 6 will be described as an example. In the iron (III) ion (Fe ³⁺ ) and the copper (II) ion (Cu ²⁺ ),
When alkali hydroxide is added to a solution containing each of these ions, the hydrogen ion concentration (pH) that forms hydroxide differs, and the pH at which iron hydroxide Fe (OH) ₃ is generated is 3 or more. And the pH at which copper hydroxide Cu (OH) ₂ is produced is 5 or more.

However, the Fe--Cu used in Experiment 6 was used.
Precipitation of the co-precipitate is almost complete at pH 4, below the pH of 5 at which Cu (OH) ₂ precipitates.

This is because a hydroxide of Cu alone is produced by adding alkali hydroxide (sodium hydroxide (NaOH) in each of the above examples) to a solution in which Fe ³⁺ and Cu ²⁺ coexist. This is because the Fe-Cu coprecipitate precipitates at a pH lower than the pH required.

Fe and Cu have different hydrogen ion concentrations for forming hydroxide precipitates, and anion adsorption sites (for example, [Cu (OH)] ⁺ ) are present in the coprecipitated Fe-Cu coprecipitate. It is preferable because it can be formed efficiently, and thus a high adsorption capacity can be obtained relatively easily, but the present invention is not limited to this.

In the anion adsorbents used in Experiments 7 and 8, Fe-Mg coprecipitate and Al-Mg coprecipitate, combined hydroxide precipitates of the metals are formed. Since the hydrogen ion concentration is different, it is preferable since a high adsorption capacity for anions can be obtained, but the present invention is not limited to this, and other metal combinations not described in this example can be used. Even if there is a difference in the hydrogen ion concentration at which hydroxide precipitation is generated between the combined metals, it is possible to obtain a high adsorption capacity for anions.

Adsorption of each anion containing arsenic, antimony, selenium, molybdenum, chromium, etc. existing as anions in the solution to the anion adsorption sites of these anion adsorbents is harmful. The element can be removed.

(Experiment 9: Adsorption and desorption of harmful element ions in the anion adsorbent) Next, the adsorbed harmful elements were removed from the Fe-Cu coprecipitate, which is the anion adsorbent that adsorbed the harmful elements in Experiment 6 above. A method of attaching and detaching will be described.

First, selenate ion (the selenium element is 10
To 100 ml of a solution (having a concentration of 0 mg · dm ^-3 ), 1 g of Fe-Cu coprecipitate, which is an anion adsorbent, was added to convert the selenate ion in the solution into an anion adsorbent. Adsorb.

After 15 minutes, the concentration of elemental selenium in the selenate ion solution was measured and found to be 0.09 mg · dm ^−3.
Fell to. That is, 99% or more of selenate ions were adsorbed in the Fe-Cu coprecipitate.

Next, the selenate ion solution was filtered to recover the Fe-Cu coprecipitate, and the recovered Fe-Cu coprecipitate was added to 50 ml of an alkaline solution adjusted to pH 13 with a sodium hydroxide solution. Added to.

After 5 minutes, the measurement result of the selenium element concentration in the alkaline solution was 180 mg · dm ^−3, and
-About 9 selenate ions adsorbed in the Cu coprecipitate
While desorbing 0%, the elemental selenium concentration in the solution was concentrated to about 1.8 times.

(Experiment 10: Adsorption by Reuse in Anion Adsorbent) Next, a method for reusing the Fe—Cu coprecipitate from which the selenate ion is desorbed will be described.

First, the selenate ion (the selenium element is 10
To 100 ml of a solution (having a concentration of 0 mg · dm ⁻³ ), 1 gram of Fe—Cu hydroxide desorbed with selenate ions was added, and the pH was adjusted to 5 with hydrochloric acid (HCl).
After measuring the concentration of the selenate ion solution after 5 minutes,
The elemental selenium concentration in the solution was 0.06 mg · dm ⁻³ , which resulted in 99% or more of the selenate ion in the solution being adsorbed by the Fe—Cu coprecipitate. As a result, even an anion adsorbent that has once desorbed selenate ions and then desorbed can be reused.

The graph shown in FIG. 9 discloses the data on the pH dependence of the amount of selenate ion adsorbed in the Fe--Cu coprecipitate, and the results of Experiments 9 and 10 described above are guaranteed. Has become.

More specifically, as shown in FIG. 9, the Fe-Cu coprecipitate shows that the lower the pH of the solution containing selenate ions, the more the adsorption amount of selenate ions per gram of Fe-Cu coprecipitate. , And conversely, the higher the pH of the solution, the lower the adsorption amount of selenate ions.

As described above, the anion adsorbent Fe-Cu hydroxide used in Experiments 9 and 10 was
When the pH of the solution used for anion adsorption increases, the adsorption capacity of selenate ions decreases, and when selenate ions are adsorbed, the adsorbed selenium ion may be desorbed when the pH increases. When the pH becomes low, the adsorbing ability of selenate ions becomes high, and it becomes possible to adsorb selenate ions again.
As shown by 0, an anion adsorbent (Fe-Cu coprecipitate)
Is to adjust the pH of the solution to alkaline pH 13 with a base or the like to desorb the anions, or to once desorb the anions and then adjust the pH of the solution to an acidic pH of 5 to adsorb the anions again. Is possible.

The anion adsorbents Fe-Mg coprecipitate and Al-Mg coprecipitate used in Experiments 7 and 8 have almost the same properties as the Fe-Cu coprecipitate. Therefore, it is possible to adsorb or desorb the anion by adjusting the pH of the solution, or to adsorb the anion again after the desorption of the ion.

In addition to the above selenium, each experiment 6
As with selenium, it was possible to adsorb and desorb harmful elements such as antimony, molybdenum, and chromium used in the harmful element removal test in Experiment 8.

(Experiment 10: Comparison of anion adsorbing ability between lead-containing anion adsorbent and lead-free anion adsorbent) Next, the anion adsorbent does not contain the above-mentioned harmful substance lead. Fe-Cu coprecipitate, Fe-Mg coprecipitate, Al-
Mg coprecipitate and Fe-Pb coprecipitate, which is a conventionally used lead-containing anion adsorbent, and residual selenium when adsorbing selenate ion, which is one of the harmful elements described above. Comparison of element concentrations will be described with reference to FIG.

The method of the experiment was carried out in the same manner as in each of Experiments 6 to 8 above, and pure lead-free anion adsorbents (Fe-Cu) prepared in Production Method 3 to Production Method 5 were used. Coprecipitate, Fe-Mg coprecipitate, Al-Mg coprecipitate) and Fe-Pb coprecipitate, which is an anion adsorbent containing lead, for 3000.
Oyobi to be mg · dm ^-3, the addition of selenate ion solution to a elemental selenium concentration 10 mg · dm ^-3, stirring is carried out for a solution using a glass syringe at predetermined time intervals 0.
01 liter was collected and filtered to quantify the remaining elemental selenium.

As shown in FIG. 10, the results show that four kinds of anion adsorbents (Fe-Cu coprecipitate, Fe-Mg coprecipitate, used at 30 minutes after the start of the experiment, Al-Mg
The co-precipitate and the Fe-Pb co-precipitate) were all used, and the concentration was below the selenium drainage standard value of 0.1 ppm.

As described above, the above-mentioned four kinds of anion adsorbents (Fe-precipitate, Fe-Cu coprecipitate, Fe-Mg coprecipitate, Al, which do not contain lead, which may adversely affect the environment, are added. −
Even when using (Mg coprecipitate), it is possible to obtain an adsorption effect comparable to that when using an anion adsorbent containing lead (Fe-Pb coprecipitate), and reusable Since a highly practical anion adsorbent can be obtained, harmful elements can be removed without using lead, and it becomes easy to preserve the natural environment.

[0070]

The present invention has the following effects. Since these anion adsorbents do not contain lead, not only does lead elute, but they also have high adsorption capacity comparable to conventional anion adsorbents containing lead elements. Moreover, a highly practical anion adsorbent that can be reused can be obtained. Further, by eluting the adsorbed anion, the element contained in the anion can be efficiently recovered.

[Brief description of drawings]

Fig. 1 Removal test of selenate ion using Fe-precipitate

Fig. 2 Selenate ion removal test using Fe-precipitated product

FIG. 3: pH dependence test of selenate ion adsorption on Fe-precipitate

Fig. 4 Repeated adsorption / desorption test of selenate ion by Fe-precipitate

FIG. 5: Removal test of various anions by Fe-precipitate

Fig. 6 Hazardous element removal test using Fe-Cu coprecipitate

Figure 7: Removal test of harmful elements using Fe-Mg coprecipitate

FIG. 8: Hazardous element removal test using Al-Mg coprecipitate

FIG. 9: pH dependence of selenate ion adsorption amount in Fe-Cu coprecipitate

FIG. 10: Performance comparison of various anion adsorbents

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[Procedure amendment]

[Submission date] June 25, 2003 (2003.6.2
5)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

2. An anion adsorbent according to claim 1 , which is brought into contact with a solution containing an anion to adsorb the anion contained in the solution onto the anion adsorbent. Removal method.

3. By treating the anion adsorbent of claim 1 , which has adsorbed anions, with an alkaline solution,
A method for regenerating an anion adsorbent, which comprises eluting adsorbed anions.

The method according to claim 4 anion adsorbent claim 1 which has adsorbed anions, by treatment with an alkaline solution,
An element recovery method in which an adsorbed anion is eluted to recover an element contained in the anion.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

In order to solve the above problems, the anion adsorbent of the present invention is an amorphous iron hydroxide-based precipitation product obtained by adding an alkali to an iron ion solution . It is characterized by being. Since these anion adsorbents do not contain lead, not only does lead elute, but they also have high adsorption capacity comparable to conventional anion adsorbents containing lead elements. Moreover, a highly practical anion adsorbent that can be reused can be obtained. Further, by eluting the adsorbed anion, the element contained in the anion can be efficiently recovered.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

The method for removing anions according to the present invention comprises the steps described above.
The anion adsorbent of Item 1 is brought into contact with a solution containing anions, and the anions contained in the solution are adsorbed to the anion adsorbent. Can be removed.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

The method for regenerating an anion adsorbent according to the present invention is characterized in that the anion adsorbent of claim 1 having adsorbed anions is treated with an alkaline solution to elute the adsorbed anions. In addition, by regenerating the anion adsorbent that has adsorbed anions in the alkaline solution, it can be repeatedly used as an anion adsorbent and can efficiently recover the elements contained in the anion. You can

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) B01J 20/34 B01J 20/34 G (72) Inventor Atsushi Shibayama 9-33, Aki, Akita City, Akita City Downtown Town No. 3 F Term (Reference) 4D017 AA01 BA11 BA13 CA04 CB01 DA07 DB10 4D024 AA04 AB14 AB16 BA14 BB01 BC04 CA06 DA07 4G066 AA15B AA16B AA20B AA27B AA32A AA36A AA39A AA53A BA36 CA21 CA32 CA46 FA46 CA32 CA46 FA46 CA32 FA

Claims (6)

[Claims] 1. An anion adsorbent comprising an amorphous iron hydroxide-based precipitation product obtained by adding an alkali to an iron ion solution. 2. An anion adsorbent comprising an amorphous co-precipitate obtained by adding an alkali to a solution containing at least two kinds of metal elements which forms a hydroxide precipitate at different hydrogen ion concentrations. An anion adsorbent characterized in that the at least two kinds of metal elements are metal elements other than lead. 3. The combination of the two kinds of metal elements is
The anion adsorbent according to claim 2, which is Fe and Cu, Fe and Mg, or Al and Mg. 4. Contacting the anion adsorbent according to any one of claims 1 to 3 with a solution containing anion to cause the anion adsorbent to adsorb the anion contained in the solution. A characteristic method for removing anions. 5. An anion adsorbent, characterized in that the adsorbed anion is eluted by treating the anion adsorbent according to any one of claims 1 to 3 having an adsorbed anion with an alkaline solution. How to play. 6. The anion adsorbent according to claim 1, which adsorbs anions, is treated with an alkaline solution to elute the adsorbed anions and recover the elements contained in the anions. Element recovery method.