JP2949227B1 - Hydrous bismuth compounds with excellent inorganic anion exchange properties and their production - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a hydrated bismuth compound excellent in inorganic anion exchangeability. SOLUTION: The formula: BiO (NO ₃ ) .XH ₂ O (5 /
A powder of bismuth oxide having the formula: Bi ₂ O _{3 and} a bismuth nitrate having the formula: Bi (NO ₃ ) ₃ .5H ₂ O The hydrate is prepared by reacting at room temperature to 80 ° C. as a powder mixture by adjusting the molar ratio of the hydrate to the powder to be 1: 1. The inorganic anion exchanger containing the hydrated bismuth compound as an active ingredient is reacted with a halide ion contained in a liquid or gas to form BiOX (X = I, Br, Cl,
Removed as F).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compound represented by the formula (NO ₃ )
And a method for removing and solidifying halide ions by using the compound. More specifically, the present invention is directed to removing halide ions from aqueous solutions and organic solvents, treating industrial wastewater containing halide ions, removing and fixing radioactive halide ions from nuclear power wastewater, The present invention relates to a hydrated bismuth compound useful for recovery and removal of a volatile component, and a method for removing and solidifying a halide ion using an ion exchanger containing the same as an active component.

[0002]

BACKGROUND OF THE INVENTION Known compounds which are directly related in composition to the compounds of the present invention include BiO (NO ₃ ).
A compound represented by the formula of XH ₂ O (X = 2, 1, 1/2, and 0) was reported in an old document (1927), and the summary of the compound was given in Gumelin Handbook (vol. 19, Bi).
Has been introduced. According to this, these compounds are synthesized by dissolving bismuth oxide in nitric acid and adding water little by little. Of these compounds, X = 1 and 1
The compound of the formula / 2 has also been subjected to structural analysis, but none of the structures is the same as that of the compound of the present invention. Further, there is no example in which these compounds are used as an inorganic anion exchanger. Other bismuth-based compounds containing a nitrate group have heretofore been Bi ₅ O ₇ (N
O ₃ ) and BiPbO ₂ (NO ₃ ) have been reported as inorganic anion exchangers (for example, see JP-A-6-550).
81, JP-A-9-52715). Examples of the hydrated bismuth compound that can be used as an inorganic ion exchanger include Bi ₆ O ₆ (OH) _X (NO ₃ ) _{6 -X} · nH
A compound represented by the formula of ₂ O (where 3.5 ≦ X ≦ 5.5, n is 0 or a positive integer) has been reported (JP-A-63-60112). However, although this compound exhibits excellent ion exchange performance in a solution near neutrality, it has a low proportion of OH groups in its composition and thus has poor acid or alkali resistance, and its production method Is extremely complicated.

[0003]

The present invention SUMMARY OF THE INVENTION The can as to solve the problems of the compounds shown in JP-63-60112 the above mentioned _{publications, BiO (NO 3) · XH} 2
A novel hydrated bismuth compound represented by the formula of O (5/3 ≧ X> 0) has been found, an ion exchanger containing the same as an active ingredient, and a halogen contained in a liquid or gas using the ion exchanger. BiOX (X =
I, Br, Cl, F) are provided for removing and solidifying halide ions. Further, the present invention provides
Formula powder and wherein the bismuth oxide Bi ₂ O _3: Bi (NO
In _{3) 3} · 5H ₂ O ratio of the powder of bismuth nitrate pentahydrate molar ratio l: preparation of hydrous bismuth compound to be reacted at room temperature to 80 ° C. as an adjustment to the powder mixture to be 1 to provide. The starting of the _{Bi (NO 3) 3 · 5H} 2
O starts to decompose at about 80 ° C., so that reaction is possible up to this temperature. BiO (NO ₃ ) .XH ₂ O, which is a hydrated bismuth compound of the present invention, has a very simple production method, is excellent in acid resistance, alkali resistance, and heat resistance, and has a composition containing (NO ₃ ) Since it has a group, it can be expected to function as an anion exchanger.

[0004]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, bismuth oxide (Bi
_When the powdered reagent of ₂ O ₃ ) and the powdered reagent of bismuth nitrate pentahydrate are mixed in a mortar at room temperature to 80 ° C., they readily react to form a compound having the composition represented by the above formula. This compound was confirmed to be an inorganic anion exchanger having both high ion exchange capacity and high ion exchange rate at room temperature in both acidic, neutral and alkaline solutions, and excellent stability. The invention has been completed. Further, in the present invention, the use of an inorganic ion exchanger containing a compound having the composition represented by the above formula as an active ingredient to remove chloride ions and iodide ions contained in a waste liquid and the like, and at the same time, remove a stable solid A method for immobilizing the compound is also provided. The present invention relates to BiO (NO ₃ ) .XH ₂ O (5/3
.Gtoreq.X> 0), wherein halide ions can be effectively removed by an inorganic anion exchanger containing the compound as an active ingredient. At room temperature, ion exchangeability is effective in any of acidic, neutral and alkaline aqueous solutions.

[0005] Some bismuth oxide nitrate compounds are known to have ion-exchange properties with respect to halide ions. However, such compounds have a hydroxyl group or a hydroxyl group contained in the composition. It has been shown that nitrate groups exchange ions with halide ions. Also in the case of the hydrated bismuth compound of the present invention, it was confirmed that the composition contained a nitric acid group, and this ion exchanged with a halide ion. In the present invention, it is important that the ratio of Bi to (NO ₃ ) in the composition of the hydrated bismuth-based ion exchanger is 1: 1. This is because, in the present invention, the following reaction formula (1) is assumed for ion exchange between a halide ion and a hydrated bismuth compound. BiO (NO ₃ ) · 0.5H ₂ O + X ⁻ → BiOX + (NO ₃ ) ⁻ + 0.5H ₂ O (1) And generated BiOX (X = I, Br, Cl, F)
Is a solid which is stable even in an aqueous solution, and can be separated from the solution after the reaction to store a halide ion as a stable solid. Therefore, the ion exchanger containing the hydrated bismuth compound of the present invention as an active ingredient can also be used as a solidified radioactive iodide ion or chloride ion.

[0006] These facts have been confirmed by actual experiments using iodide ions and chloride ions. The structure of the solid after the reaction was examined by powder X-ray diffraction. As a result, pH =
Except for the reaction product at 13, all reaction products are
BiOI and BiOCl. That is, pH = 1
Equation (1) holds true for the reactions in the solutions from to 12. P
The reaction products in the solution with H = 13 were not those described above. In the case of iodide ions, Bi ₄ O ₅ I ₂ and Bi
_When the mixture of ₅ O ₇ I, and chloride ions,
A mixture of Bi ₃ O ₄ Cl and Bi ₂ O ₂ CO ₃ formed. As will be described later, this means that the ion exchange capacity
= 13 causes a decrease. The water initially contained in the ion exchanger is not directly involved in the reaction. However, it is presumed that the structural water contributes to the stabilization of the compound.

[0007]

EXAMPLES The method for producing a hydrated bismuth compound according to the present invention will be described below with reference to examples. Example 1 Commercially available bismuth oxide (Bi ₂ O ₃ ), 4.66 g
Powder and commercial bismuth nitrate pentahydrate (0.01 _{mol) (Bi (NO 3) 3} · 5H 2 O), 4.85g (0.0
(1 mol) as a raw material, mixed well using a mortar, and allowed to stand at room temperature for several hours to react. 1A and 1B show X-ray diffraction patterns of the raw materials, and FIG. 1C shows an X-ray diffraction pattern of the powder after the reaction. From these figures, it is clear that the substance shown in FIG. 1C is not a mixture of the raw materials but a reaction product. Also, A, B, C in FIG.
2 shows the change over time of the reaction product in the form of a powder X-ray diffraction pattern. From FIG. 2 it can be seen that the reaction is almost complete within about 6 hours after initiation, and then progresses slightly to 20
You can see that it is completed after a day. After the reaction product was air-dried in air at room temperature for a long time (a sample after 9 months from mixing), the composition of the product was determined by elemental analysis of nitrogen and hydrogen, and BiO (NO ₃ ) · 0 It was determined to .5H ₂ O.

The fact that the compound of the present invention is not a mere mixture of the two starting materials but a reaction product was confirmed not only by powder X-ray diffraction but also by thermogravimetric analysis. Curves A and B in FIG. 3 represent Bi (NO ₃ ) ₃ .5H ₂ O and BiO (NO ₃ ) .0.5H ₂ 2 shows a thermogravimetric curve obtained when each sample of O was heated in a stream of argon from room temperature to 700 ° C. under the same conditions. Bismuth oxide is stable to heating and shows no weight change under the experimental conditions described above. Thus, if the raw materials have not reacted, curves A and B should show similar changes to heating, even considering the bismuth oxide weight. The two curves shown in FIG. 3 show different changes, indicating that the two compounds are non-identical reaction products.

Hereinafter, an inorganic anion exchange reaction using the hydrated bismuth compound of the present invention will be described with reference to examples. Example 2 BiO (NO ₃ ) · 0.5H ₂ O, 0.2 g (4.3 ×
10 ^-4 mol) and 0.2 mol dm ^-1 of NaI solution (three kinds of solutions: pH = 1, 7, 13: pH is adjusted using HNO ₃ and NaOH), 4 ml (I ⁻ : about 8 ×
10 ⁻⁴ g ion) was placed in a container with a lid, and allowed to react in a thermostat at a temperature of 25 ° C. for various times, and the progress of the reaction was examined. During the reaction, by shaking the container,
The solution was stirred. After a certain period of time, the container was taken out, the liquid and the solid were separated, and the concentration of iodide ions remaining in the solution was measured by ion chromatography to determine the amount of removed ions.

FIG. 4 of the accompanying drawings shows the relationship between the reaction time for iodide ions and the ion exchange capacity. In addition, the ion exchange capacity means the ion exchanger 1
It is represented by the number of equivalents (or milligram equivalents) of the adsorbed or ion-exchanged ion per g, and the unit is eq g ^-1.
(Equivalents per gram) or meq g ^-1 (milligram equivalents per gram). The curve in the figure means that the reaction speed becomes faster as the value approaches the maximum ion exchange capacity in a short time. At any pH, the onset reaction proceeded very quickly and the concentration of iodide ions removed from the solution 60 minutes after the start of the reaction was 85% (pH = 1), 70% of the maximum value for each solution.
(PH = 7), reaching 87% (pH = 13). The time at which the reaction is terminated depends somewhat on the pH, about 5 hours at pH = 1 and 13, and about 20 hours at pH = 7.

Example 3 BiO (NO ₃ ) .0.5H ₂ O, 0.2 g (4.3 ×
^10-4 mol) and 0.2 mol dm ^-1 of NaCl solution (three kinds of pH = 1, 7, 13: HNO ₃ and NaO)
H), 4 ml (Cl ⁻ : about 8 × 10
⁻⁴ g ion) was placed in a container with a lid, and allowed to react in a thermostat at a temperature of 25 ° C. for various times, and the progress of the reaction was examined. During the reaction, the solution was agitated by shaking the vessel. After a certain period of time, the container was taken out, the liquid and the solid were separated, and the concentration of chloride ions removed from the solution was measured by ion chromatography to determine the amount of removed ions.

FIG. 5 of the accompanying drawings shows the relationship between the reaction time and the ion exchange capacity for chloride ions. The curves in the figure show that the rise reaction proceeds extremely quickly at any pH, and the concentration of chloride ions remaining in the solution 60 minutes after the start of the reaction is the maximum value of each solution. 99% (pH = 1),
It reaches 94% (pH = 7) and 100% (pH = 13). The time at which the reaction ends varies slightly depending on the pH,
At pH = 1 and 6, about 5 hours, and at pH = 13 within 1 hour.

Example 4 In this example, the ion exchange capacity of BiO (NO ₃ ) .0.5H ₂ O in NaI solutions showing various pH values was measured. BiO (NO ₃ ) · 0.5H ₂ O,
0.2 g and 4 ml of a 0.2 mol dm ^-3 NaI solution were placed in a container with a lid, and the container was hermetically sealed.
The reaction was performed for 0 hours. During the reaction, the solution was agitated by shaking the vessel. After the reaction, the container was taken out, the liquid and the solid were separated, and the concentration of iodide ions remaining in the solution was measured by ion chromatography to determine the ion exchange capacity. The pH of the solution was changed from 1 to 13, but the pH was adjusted using a nitric acid solution on the acidic side and a sodium hydroxide solution on the alkaline side.

FIG. 6 of the accompanying drawings shows the relationship between the ion exchange capacity of iodide ions measured at 25 ° C. and the pH of the aqueous solution. As is clear from the figure, it can be seen that the compound of the present invention has a large ion exchange capacity in all the measured pH ranges. The ion exchange capacity shows a maximum value at pH = 1, a slightly smaller but almost constant value between pH = 2 and 12, and a considerably smaller value at pH = 13. However, the value of pH = 13 is almost the same as the value of the ion exchange capacity for the iodide ion of the bismuth-based anion exchanger invented so far, and shows a considerably large value at other pH values. .

Embodiment 5 In this embodiment, NaCl having various pH values was used.
The ion exchange capacity of BiO (NO ₃ ) .0.5H ₂ O in the solution was measured. BiO (NO ₃ ) · 0.5H ₂ O,
0.2g and 0.2ml dm ^-3 NaCl solution 4ml
Was sealed in a container with a lid, and reacted at 25 ° C. for 20 hours in a thermostat. During the reaction, the solution was agitated by shaking the vessel. After the reaction, the container was taken out, the liquid and the solid were separated, and the concentration of chloride ions remaining in the solution was measured by ion chromatography to determine the ion exchange capacity. The pH of the solution was varied from 1 to 13.

FIG. 7 of the accompanying drawings shows the relationship between the ion exchange capacity of chloride ions measured at 25 ° C. and the pH of the aqueous solution. As is clear from the figure, it can be seen that the substance of the present invention has a good ion exchange capacity in the whole measured pH range. Ion exchange capacity is pH = 1 to 12
It shows a nearly constant value between and only at pH = 13. As in the case of iodide ions, the value of pH = 13 is almost the same as the value of the ion exchange capacity of the bismuth-based anion exchanger invented so far for chloride ions. It shows a fairly large value.

Example 6 BiO (NO ₃ ) .0.5H ₂ O, about 0.76 g (about 2.75 × 10 ⁻³ gram molecule) and 0.05 mol d
m ^-3 NaI or NaCl solution (pH = 1, pH = 7
And pH = 13) 5 ml (I ^- and C
l ⁻ : about 2.5 × 10 ⁻⁴ gram ion) were placed in separate containers with lids, sealed, and placed in a thermostat at 25 ° C. at 25 ° C.
The reaction was carried out for a time while shaking the container. In this embodiment, the ratio of the ion exchanger to iodide ions and chloride ions is larger than that in Examples 1, 2, 3, and 4. Table 1 shows the results. As is apparent from Table 1, the halide ions were efficiently removed in any of the solutions at pH = 1, pH = 7 and pH = 13.

[0018]

[Table 1]

[0019]

As described in detail above, the present invention provides:
The present invention provides a hydrated bismuth compound having (NO ₃ ) in its composition by a novel and simple production method. According to the present invention, the ion exchange capacity and the ion exchange rate are large, the acid resistance and the alkali resistance are excellent, and the acid and neutral The present invention provides a hydrated bismuth compound which is effective in both aqueous and alkaline aqueous solutions, and a halide ion removing and solidifying material using an inorganic anion exchanger containing the same as an active ingredient.

[Brief description of the drawings]

FIG. 1 shows a powder X-ray diffraction pattern. A is
In the case of compound Bi ₂ O ₃ , B is a compound Bi (NO ₃ )
For ₃ · 5H ₂ O, C, the compound BiO (NO ₃₎ ·
XH ₂ O (reaction time 20 days).

FIG. 2 is a view showing a powder X-ray diffraction pattern of a compound BiO (NO ₃ ) .XH ₂ O. A indicates a reaction time of 6:00, B indicates a reaction time of 20 days, C indicates a reaction time of 4
9 days.

FIG. 3 is a diagram showing a thermogravimetric curve. A is a compound Bi
(NO ₃₎ For ₃ · 5H ₂ O, B, the compound BiO
(NO ₃ ) · 0.5 H ₂ O.

FIG. 4 is a graph showing a change in ion exchange capacity of an ion exchanger with respect to iodide ions when a reaction time is changed in a solution of pH = 1, 7, and 13.

FIG. 5 is a graph showing a change in ion exchange capacity with respect to chloride ions of an ion exchanger when a reaction time is changed in a solution of pH = 1, 7, 13;

FIG. 6 is a graph showing the value of the ion exchange capacity of an ion exchanger with respect to iodide ions in solutions at various pHs.

FIG. 7 is a graph showing the value of the ion exchange capacity of an ion exchanger with respect to chloride ions in solutions having various pH values.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C01G 29/00 B01J 41/02 B01J 41/10 C02F 1/42

Claims (4)

(57) [Claims] 1. The formula: BiO (NO ₃ ) .XH ₂ O (5 /
A water-containing bismuth compound excellent in inorganic anion exchangeability represented by 3 ≧ X> 0). 2. The formula according to claim 1, wherein: BiO (NO ₃ ).
An inorganic anion exchanger containing, as an active ingredient, a hydrated bismuth compound represented by XH ₂ O (5/3 ≧ X> 0). 3. The method according to claim 2, wherein the inorganic anion exchanger according to claim 2 is reacted with halide ions contained in a liquid or a gas to remove BiOX (X = I, Br, Cl, F). To remove inorganic anions. 4. Bismuth oxide powder of formula: Bi ₂ O ₃ and formula: Bi (NO ₃ ) _{3 2. The} method according to claim 1, wherein the molar ratio of 5H ₂ O to bismuth nitrate pentahydrate powder is adjusted to 1: 1 to react as a powder mixture at room temperature to 80 ° C. A method for producing a hydrated bismuth compound.