JPH0255380B2 - - Google Patents

Description

[Detailed description of the invention]

(1) Purpose of the invention [Field of industrial application] The present invention is directed to a novel bismuth compound and its uses, including various uses of ion exchange and adsorption, such as removal of impurity ions from aqueous solutions and organic solvents, treatment of industrial waste liquids, Recovery of valuables from industrial wastewater and seawater,
Manufacturing of high-purity chemicals, adsorption and fixation of impurity ions in solid materials related to electrical and electronic fields, adsorption recovery and adsorption removal of ionic components in gases, ion exchange, PH buffering and PH adjustment using adsorption properties, etc. The present invention relates to an inorganic anion exchanger used in the following applications. [Prior Art] Conventionally, as inorganic anion exchangers, hydrous magnesium oxide, hydrous aluminum oxide, hydrous zirconium oxide, hydrous titanium oxide, hydrous tin oxide, hydrous thorium oxide, hydrous iron oxide, hydrous bismuth oxide, hydrotalcite, and Hydroxyapatite and the like are known. Generally speaking, inorganic ion exchangers including inorganic anion exchangers are amphoteric ion exchangers. That is,
It exhibits cation exchange properties on the alkaline side and anion exchange properties on the acidic side. If the inorganic ion exchanger is M(OH) _o , and the ions to be captured are represented by B ⁺ and A ^- , on the alkaline side, (1)
As shown in the equation, on the acidic side, ion exchange is performed as shown in equation (2). M(OH) _o +B ⁺ M(OH) _o-1 OB+H ⁺ …(1) M(OH) _o +A ^- M(OH) _o-1 +OA+OH ^-... (2) Anion exchange reaction and cation exchange reaction The pH that becomes equal is called the isoelectric point, and at a pH around this point, neither cation exchange nor anion exchange properties appear. The isoelectric point varies somewhat depending on the type of ion exchanger, but is generally around PH5. For example, hydrous zirconium oxide has a pH of about 6, hydrous titanium oxide has a pH of about 4, and hydrous tin oxide has a pH of about 5. As is clear from this, near neutrality,
Inorganic ion exchangers have the disadvantage that they do not exchange ions. Furthermore, in the case of inorganic anion exchangers, there is also the problem of liquid contamination. In other words, after adsorbing anions on the acidic side, when desorbing the adsorbed ions (regeneration of the ion exchanger),
Normally, an alkaline aqueous solution such as NaOH aqueous solution is used, but if the inorganic ion exchanger that has been subjected to desorption treatment is then brought into contact with an acidic solution again for ion adsorption, the following ion exchange reaction occurs, and during regeneration, Adsorbed cations, such as ^Na ing. M (OH) _o-1 (OB) + H ⁺ Cl ^- M (OH) _o + B ⁺ Cl ^- For the reasons shown above, inorganic ion exchangers with isoelectric properties in the weak acid to neutral range are anion exchangers. It is of little practical use. In addition, hydrated aluminum oxide and hydroxyapatite have a small ion exchange capacity, and hydrated magnesium oxide has a large solubility, making them difficult to use industrially. Hydrotalcite and hydrous bismuth oxide exhibit only anion exchange properties and have relatively excellent chemical resistance and heat resistance. However, hydrotalcite is highly soluble in hot water at temperatures above 100°C and has poor heat resistance. On the other hand, hydrous bismuth oxide has a very large exchange capacity in acidic conditions and is stable in water, making it relatively excellent as an inorganic ion exchanger, but its ion exchange capacity near neutrality is small and its exchange rate is low. It has the disadvantage of being slow. In the literature, hydrous bismuth oxide used as an inorganic anion exchanger has various chemical formulas as shown below. _Bi (OH) ₃ , _Bi2O3・_3H2O , _HBiO2 , _{H3BiO3 ,}
HBiO ₂ , BiO・OH (INORGANIC ION
EXCHANGE MATERIA LS, CRC Press,
Inc. (Boca Raton, Florida), published 1981 P.180~
182). These compounds can be obtained by hydrolyzing an aqueous solution of a soluble salt of bismuth, but common manufacturing methods include neutralizing an aqueous solution of bismuth nitrate with aqueous ammonia, or diluting an aqueous solution of bismuth mannitol complex with a large amount of water and hydrolyzing it. There are known methods to do this. [Problems to be Solved by the Invention] Conventional hydrous bismuth oxide, which is relatively excellent as an inorganic anion exchanger, has the disadvantages of low ion exchange capacity near neutrality and slow exchange rate, as described above. have. Therefore, there has been a strong demand for inorganic anion exchangers that are stable, highly basic, and have a high ion exchange rate, especially inorganic anion exchangers made of bismuth-based compounds. (2) Structure of the Invention [Means for Solving Problems] The present inventors have conducted intensive studies on the synthesis of a new hydrous bismuth oxide that can be used as an inorganic anion exchanger, and as a result, have developed a novel nitric acid We succeeded in synthesizing a bismuth hydrolysis product, and this compound has high ion exchange capacity and ion exchange rate near neutrality.
Moreover, it was confirmed that the inorganic anion exchanger had excellent stability, and the present invention was completed. That is, the present invention provides Bi ₆ O ₆ (OH) _x (NO ₃ ) _6-x・nH ₂ O
The present invention relates to a bismuth compound represented by the formula (3.5≦x≦5.5, n is 0 or a positive number) and an inorganic anion exchanger containing this compound as an active ingredient. In the field of crystal chemistry research on inorganic compounds, the hydrolysis reaction products of bismuth have been studied in relatively detail, starting from bismuth nitrate, and the chemical species known to date include seeds, etc. There is something. ΓBiO・NO ₃ (Bismuth oxynitrate) Γ [Bi ₆ O ₄ (OH) ₄ ] [OH] (NO ₃ ) ₅・0.5H ₂ O (PH
Products at 1.04-1.88] Γ[Bi ₆ O ₆ (OH)] (NO ₃ ) ₅・2.5H ₂ O Γ [Bi ₆ O ₆ (OH) ₂ ] (NO ₃ ) ₄・2H ₂ O Γ Bi ₆ O ₆ (OH) ₃ ] (NO ₃ ) ₃・1.5H ₂ O Γ [Bi ₆ O ₄ (OH) ₄ ] (NO ₃ ) ₆・4H ₂ O (Monatshefte fur Chemie 104365~375
(1973), Cryst.Struct.Comm.(1979), 8, 69.) What all of the above compounds have in common is that the hydrolysis product of bismuth is an oxy compound and is a polymer. Bismuth atom is 6
Since the individual is the basic unit, the current theory is that Bi atoms occupy six vertices of the octahedral structure. However, ion exchange studies of the above-mentioned chemical species have not been conducted. Furthermore, the above-mentioned species are products in the low pH range, and all have low basicity. That is, the OH group/NO ₃ group ratio of each chemical species is 1 or less, and no basicity higher than this has been reported so far. The bismuth compound of the present invention can be produced by adding an alkaline aqueous solution to a nitric acid aqueous solution of bismuth nitrate while controlling the hydrolysis reaction conditions. As mentioned above, the hydrolysis products of bismuth are
The basic unit is an oxy compound containing six Bi atoms, and is represented by Bi ₆ O ₆ (OH) _x (NO ₃ ) _6-x ·nH ₂ O. Conventionally, those having an x/(6-x) ratio of 1 or less have been found, but none exceeding 1 has been found. The conventional x/(6-x) ratio is less than 1, that is, x is 3
The hydrolysis reactions of the following are estimated as follows. Reaction in a solution with ΓPH of 1 or less 6Bi ³⁺ +12H ₂ OBi ₆ (OH) ⁶⁺ ₁₂ +12H ⁺ …(3) Oxylation precipitation reaction in the vicinity of ΓPH1.2 Bi ₆ (OH) ⁶⁺ ₁₂ +6NO ₃ ^- →Bi ₆ O ₆ (NO ₃ ) ₆ +6H ₂ O (4) where the multimer Bi ₆ O ₆ (NO ₃ ) ₆ is generally designated as BiONO ₃ as bismuth oxynitrate. Furthermore, in the hydrolysis reaction at high pH, Bi ₆ O ₆
(NO ₃ ) The NO ₃ group of ₆ is successively substituted with OH. ΓBi ₆ O ₆ (NO ₃ ) ₆ →Bi ₆ O ₆ (OH) (NO ₃ ) ₅ …(5) ΓBi ₆ O ₆ (OH) (NO ₃ ) ₆ →Bi ₆ O ₆ (OH) ₂ (NO ₃ ) ₄ …(6) ΓBi ₆ O ₆ (OH) ₂ (NO ₃ ) ₄ →Bi ₆ O ₆ (OH) ₃ (NO ₃ ) ₃ …(7) All of the above chemical species have water of hydration. As mentioned above, the production of a more basic compound containing a nitric acid group has not been reported. The reason for this is that the more highly basic
This is presumed to be because Bi ₆ O ₆ (OH) ₆ , which is the final sequential reaction product, easily transfers to the known 3 (Bi ₂ O ₃ .H ₂ O), which is this structurally modified species. However, the present inventors added an _{alkaline aqueous} solution while controlling the hydrolysis reaction conditions as described below _.
(NO ₃ ) _6-x, in which x is within the range of 3.5 to 5.5, and stable and useful hydrated bismuth oxide was investigated, and the present invention was completed by successfully obtaining the target compound. [Method for producing a novel bismuth compound] The starting material is a nitric acid solution of bismuth nitrate. It is prepared by dissolving bismuth compounds such as bismuth nitrate, bismuth carbonate, and bismuth oxide in nitric acid. Since bismuth nitrate will not dissolve unless it is in an acid solution, it is necessary to have an excess of nitric acid. Although the concentration of the resulting bismuth nitrate solution is not particularly limited, it is preferably 20 to 50% by weight in terms of Bi(NO ₃ ) ₃ . If the concentration is higher than 50% by weight, the slurry concentration becomes high and uniformity is inhibited in the subsequent reaction of adding alkali to precipitate. On the other hand, if it is less than 20% by weight, the yield per batch will be low, making it uneconomical. There is no particular restriction on the concentration of free nitric acid present in excess, as long as bismuth nitrate does not precipitate and remains dissolved. However, if the amount of free nitric acid is in excess, the amount of alkali added in the next step will also increase, which is disadvantageous economically and operationally.
The preferred concentration of nitric acid is 3-10% by weight. The next step is to hydrolyze bismuth nitrate using an alkali. The type of alkali is not particularly limited, and examples thereof include lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, and sodium hydrogen carbonate. The addition rate of the alkali is preferably adjusted to the hydrolysis equilibrium. That is, since the hydrolysis reactions shown in formulas (3) and (4) above proceed quickly, and the reactions in formulas (5) to (7) are slow, they are added accordingly. Equations (3) and (4), including the meaning of maintaining the uniformity of the solution,
It is preferable to add a predetermined equivalent amount of alkali, that is, the amount of alkali necessary for complete hydrolysis, over a period of about 2 hours until the reaction shown in . The alkali addition time required for formulas (5) to (7) is 60 to 180
A range of minutes is preferred. After this, in order to increase _x of _{Bi 6} O ₆ ( _OH ) Preferably, an alkali is added. The reason for this is that the equilibrium reaction is slow after equation (7),
With short addition times, OH is not consumed and the reaction mixture
This is because there is a risk that the pH will become higher than necessary, and the transition to undesirable products such as Bi ₂ O ₃ and H ₂ O will progress all at once. On the other hand, if the addition time is too long, there is a risk of metastasis occurring, which is undesirable. Although the water-soluble concentration of the alkaline substance used for hydrolysis is not particularly limited, it generally depends on the addition time, but the hydrolysis reaction can be carried out in the early stage (up to equation (4)), middle stage (up to equation (7)), and latter stage (up to equation (7)). 7) After that), it is desirable to lower the concentration in order, with the first half being about 20% by weight,
The concentration is preferably about 10% by weight in the middle stage and about 5% by weight in the latter stage. Whether the temperature of the hydrolysis reaction is high or low, it does not have much effect on the composition of the final product, but the amount of products produced at low temperatures dissolved in hot water is greater than those produced at high temperatures. However, it has the disadvantage of being slightly inferior in heat resistance and hot water stability. Further, the reaction rate decreases as the temperature decreases, so the reaction temperature is preferably 10 to 60°C, more preferably 20 to 50°C. The product of the reaction is filtered, washed with water and, if necessary, dried and powdered. Any drying method may be used as long as attached water can be removed. Bi ₆ O ₆ (OH) _x (NO ₃ ) _6-x produced in the present invention
nH ₂ O of the compound represented by nH ₂ O (3.5≦x≦5.5, n is 0 or a positive number) is hydration water,
Here, the value of n is usually about 0 to 0.8, but it can be adjusted by changing the drying temperature, drying time and drying method in the drying process. Particularly when using organic solvents or solid systems, if desorption of water is inconvenient, it may be adjusted during drying. The method of pulverization is not limited as long as it can be pulverized to a particle size suitable for the purpose of use. [Function] Bi ₆ O ₆ (OH) _x (NO ₃ ) _6-x・nH ₂ O of the present invention (however,
When used as an inorganic anion exchanger, the compound represented by 3.5≦x≦5.5, where n is 0 or a positive number, has a higher ion exchange capacity and exchange rate near neutrality than ordinary hydrous bismuth oxide. is large and has excellent heat resistance. Here, the value of x can be freely determined by measuring the weight and concentration of the raw material used with high precision and then adding a calculated amount of alkali under the above conditions. The ion exchange groups of this compound are NO ₃ groups and OH
The NO ₃ group, which occurs in both groups, has a larger ion exchange capacity and exchange rate than the OH group. Therefore, this compound has a large ion exchange capacity and rate near neutrality. This difference is particularly noticeable for halogen ions such as F ^- , Cl ^- and Br ^- . If the value of x is less than 3.5, the ion exchange capacity and speed near neutrality are high, but the elution of NO ₃ to water and hot water increases, resulting in a significant decrease in water resistance and heat resistance. . Furthermore, as x becomes smaller, the amount of the compound itself dissolved also becomes larger. On the other hand, when x is larger than 5.5, there are fewer NO ₃ groups in the compound, so the ion exchange capacity and exchange rate near neutrality become smaller, and the structure becomes closer to that of normal hydrous bismuth oxide, resulting in poor water resistance. It also becomes inferior. [Inorganic anion exchanger] Bi ₆ O ₆ (OH) _x (NO ₃ ) _6-x・nH ₂ O of the present invention (however,
3.5≦x≦5.5, n is 0 or a positive number. It has excellent properties such as heat resistance and hot water stability, and can be used in a wide range of fields. Further, the compound of the present invention may be used in combination with an inorganic cation exchanger such as crystalline antimony. The shape of the inorganic anion exchanger of the present invention is not particularly limited, and may be selected depending on the purpose of use, such as powder, granules, granules, structures such as honeycomb, and membrane. When molding into particles or the like, an organic and/or inorganic binder can be used. When molding into a structure, the inorganic anion exchanger itself can be molded using a binder, or the inorganic anion exchanger can be supported on another structure. When forming into a membrane, there are methods such as forming the inorganic anion exchanger itself into a membrane, and adding the inorganic anion exchanger to the paper making process to form paper. [Examples and Comparative Examples] The present invention will be described in more detail below with reference to Examples and Comparative Examples. In the examples, "%" means "% by weight" and "parts" means "parts by weight." The method for analyzing the concentration of bismuth nitrate and free nitric acid in an aqueous solution containing excess nitric acid is as follows. Measure out a certain amount of bismuth nitrate aqueous solution, dissolve it in a large amount of water, and add NaCl aqueous solution to it. According to the following reaction formula, bismuth is precipitated,
NO ₃ ^- is liberated. Bi(NO ₃ ) ₃ +NaCl+H ₂ O →BiOCl↓+NaNO ₃ +2HNO ₃ The amount of 2HNO ₃ and free nitric acid is determined by neutralization titration. On the other hand, the bismuth concentration of the bismuth nitrate aqueous solution is determined by chelate titration (titration reagent EDTA; indicator xynol orange). By subtracting that equivalent to Bi (NO ₃ ) from the NO ₃ concentration determined earlier, the concentration of free nitric acid can be determined. Furthermore, the composition of the product bismuth compound was determined by adding a certain amount of sample to a 0.1N-NaOH aqueous solution.
After stirring for 24 hours, eluted NO ₃ ^- was measured by ion chromatography. In addition, the water content is
It was determined from the weight of the sample that decreased as a result of drying at 200°C for 2 hours. Example 1, Comparative Example 1 and Comparative Example 2 236 g of bismuth oxide was dissolved in 764 g of 31.5% nitric acid. Analysis of the concentration of bismuth nitrate in the solution
Bi (NO ₃ ) ₃ equivalent is 40.2%, free nitric acid is 4.90%
It was hot. Add 20% to this solution while keeping the reaction temperature at 25°C.
563 g of aqueous sodium hydroxide solution was added over 1 hour using a metering pump. Subsequently, 201 g of 10% sodium hydroxide aqueous solution was added for 1 hour, and 134 g of 5% sodium hydroxide aqueous solution was added.
was added in the same manner over 2 hours. After stirring for an additional hour, the precipitate was filtered through No. 2 filter paper and washed with distilled water. This was placed in a box-type dryer and dried at 100°C for 24 hours, and then ground in a tabletop grinder to obtain a bismuth compound. When we analyzed the composition of this compound, we found that Bi ₆ O ₆
(OH) _4.0 (NO ₃ ) _2.0・0.8H ₂ O, which matched the calculated value calculated from the raw materials used. X-ray diffraction results revealed that it was a slightly crystallized substance with very low symmetry.
(Example 1). 100g of bismuth nitrate pentahydrate and 40g of mannitrate
Make a viscous liquid by rubbing it in a mortar and add 500ml of distilled water.
dissolved in This was poured into a 20% aqueous sodium hydroxide solution to make a solution of approx. Gradually add 4N sulfuric acid while cooling to 15°C.
The pH was set to 10. The precipitate was filtered through No. 2 filter paper, thoroughly washed with water, placed in a box-type dryer, dried at 100°C for 24 hours, and ground in a tabletop grinder to obtain hydrous bismuth oxide. According to X-ray diffraction, this material was a highly crystalline material with a diffraction pattern different from that of Example 1 (Comparative Example 1). 90 g of sodium carbonate and 30 g of magnesium oxide were added to 500 g of water. Next, 67g of aluminum sulfate octahydrate was added to distilled water.
500 g of the aqueous solution was added to the above solution over an hour. After heating this at 90 to 100℃ for 4 hours, the precipitate No. 2
It was filtered through filter paper and thoroughly washed with distilled water. Put this in a box dryer and dry it at 100℃ for 24 hours.
Hydrotalcite Mg _4.5 , dried in tabletop grinder
Al ₂ (OH) ₁₃ CO ₃ .3H ₂ O was obtained (Comparative Example 2). 10 g of each of the compounds obtained in Example 1, Comparative Example 1, and Comparative Example 2 was added to 500 ml of 0.1N aqueous sodium chloride solution, and after stirring at 25°C for 24 hours, the chloride ion concentration in the supernatant was measured. The chloride ion exchange capacity of was investigated (Test 1). Similarly, 10 g of each compound was added to 500 ml of 0.1N sodium chloride aqueous solution, and after stirring at 85°C for 1 hour, the chloride ion concentration in the supernatant was measured, and the chloride ion exchange capacity of each substance was investigated (test 2). Similarly, 10g of each compound was added to 100ml of distilled water,
The mixture was heated under reflux for 24 hours. After cooling, the electrical conductivity in the supernatant was measured (Test 3). The results of tests 1, 2 and 3 are shown in Table 1.

[Table] Example 2 and Example 3 236 g of bismuth oxide was dissolved in 764 g of 31.5% nitric acid. Analysis of the concentration of bismuth nitrate in the solution
Bi (NO ₃ ) ₃ equivalent is 40.3%, free nitric acid is 4.90%
It was hot. A bismuth compound was obtained by carrying out the same reaction as in Example 1 except that the reaction temperature was controlled at 70°C. When we analyzed the composition of this, we found that it was Bi ₆ O ₆ (OH) _4.
1 (NO ₃ ) _1.9・0.7H ₂ O. The calculated value is Bi ₆ O ₆ (OH) _4.0 (NO ₃ ) _2.0 . Furthermore, as a result of X-ray diffraction, the symmetry was higher than that of the compound of Example 1, and some of the peaks of hydrous bismuth oxide obtained in Comparative Example 1 were also observed (Example 2). 491 g of bismuth nitrate pentahydrate, 15.7% nitric acid 509
Dissolved in g. Analysis of the concentration of bismuth nitrate in the solution
Bi( _NO3 ) ₃ equivalent is 40.0%, free nitric acid is 7.95%
It was hot. A bismuth compound was obtained by carrying out the same reaction as in Example 1 except that the reaction temperature was controlled at 5°C. When we analyzed the composition of this, we found that it was Bi ₆ O ₆ (OH) _3.
6 (NO ₃ ) _2.4・1.1H ₂ O. The calculated value is Bi ₆ O ₆ (OH) ₄ (NO ₃ ) ₂ . Moreover, as a result of X-ray diffraction, this compound was completely amorphous (Example 3). Tests 1 to 3 were conducted on the compounds obtained in Examples 2 and 3 in the same manner as in Example 1. The results are shown in Table 2.

[Table] Example 4 177 g of bismuth oxide was dissolved in 823 g of 24.8% nitric acid. Analysis of the concentration of bismuth nitrate in the solution
Bi (NO ₃ ) ₃ equivalent is 30.2%, free nitric acid is 5.9%
It was hot. Add 25% to this solution while keeping the reaction temperature at 50°C.
392 g of aqueous sodium hydroxide solution was added over 20 minutes using a metering pump. Next, add 76 g of 20% sodium hydroxide aqueous solution to 45
Similarly, 51 g of a 15% aqueous sodium hydroxide solution was added over 90 minutes. The following procedure was carried out in the same manner as in Example 1 to obtain a bismuth compound. When we analyzed the composition of this compound, we found that Bi ₆ O ₆
(OH) _5.1 (NO ₃ ) _0.9・0.6H ₂ O. Note that the calculated value was Bi ₆ O ₆ (OH) _4.5 (NO ₃ ) _1.5 , and the value of x was larger than this. Test 1 for this compound as in Example 1.
I did ~3. The results are shown in Table 3.

[Table] Example 5, Comparative Example 3 and Comparative Example 5 708 g of bismuth oxide was dissolved in 2292 g of 31.5% nitric acid. Analysis of the concentration of bismuth nitrate in the solution
Bi (NO ₃ ) ₃ equivalent is 40.1%, free nitric acid is 5.05%
It was hot. This liquid was divided into three equal parts and used in Example 5, Comparative Example 3, and Comparative Example 4. In one example, 1057 g of a 15% aqueous potassium hydroxide solution was added to this solution over 90 minutes using a metering pump while maintaining the reaction temperature at 40°C. Next, add 284 g of 10% potassium hydroxide aqueous solution to 120 g.
190 g of a 5% aqueous potassium hydroxide solution was added in the same manner over 4 hours. After stirring for an additional hour, the precipitate was filtered through No. 2 filter paper and washed with distilled water. This was placed in a box-type dryer and dried at 120°C for 15 hours, and then ground in a tabletop grinder to obtain a bismuth compound. When we analyzed the composition of this compound, we found that Bi ₆ O ₆
(OH) _4.0 (NO ₃ ) _2.0 ·0.7H ₂ O, which agreed with the calculated value (Example 5). To one of the bismuth nitrate solutions previously divided into three equal parts, 1057 g of a 15% potassium hydroxide aqueous solution was added over 90 minutes using a metering pump while maintaining the reaction temperature at 40°C. Next, add 284 g of 10% potassium hydroxide aqueous solution to 120 g.
It was added in portions in the same manner. After stirring for an additional hour, the precipitate was filtered through No. 2 filter paper and washed with distilled water. This was placed in a box-type dryer and dried at 120°C for 15 hours, and then ground in a tabletop grinder to obtain a bismuth compound. When we analyzed the composition of this compound, we found that Bi ₆ O ₆
(OH) _3.0 (NO ₃ ) _3.0・1.1H ₂ O. (Comparative Example 3). To one of the bismuth nitrate solutions previously divided into three equal parts, add 5% to this solution while maintaining the reaction temperature at 40°C.
% potassium hydroxide aqueous solution was added over 8 hours using a metering pump. After further stirring for 1 hour, the precipitate was filtered through No. 2 filter paper and washed with distilled water. This was placed in a box-type dryer and dried at 120°C for 15 hours, and then ground in a tabletop grinder to obtain a bismuth compound. When we analyzed the composition of this compound, we found that Bi ₆ O ₆
(OH) _5.7 (NO ₃ ) _0.3 ·0.4H ₂ O (Comparative Example 4). Tests 1 to 3 were conducted on the compounds obtained in Example 5 and Comparative Examples 3 and 4 in the same manner as in Example 1. The results are shown in Table 4.

[Table] Example 6, Comparative Example 5 and Comparative Example 6 491 g of bismuth nitrate pentahydrate was added to 15.7% nitric acid 509
Dissolved in g. Analysis of the concentration of bismuth nitrate in the solution
Bi (NO ₃ ) ₃ equivalent is 40.2%, free nitric acid is 7.96%
It was hot. Add 20% to this solution while keeping the reaction temperature at 30°C.
280 g of ammonia water was added over 2 hours using a metering pump. Next, add 87g of 10% ammonia water for 150 minutes.
115 g of 5% aqueous ammonia was added in the same manner over 5 hours. After stirring for an additional hour, the precipitate was filtered through No. 2 filter paper and washed with distilled water. This was placed in a box-type dryer and dried at 100°C for 24 hours, and then ground in a tabletop grinder to obtain a bismuth compound. When we analyzed the composition of this compound, we found that Bi ₆ O ₆
(OH) _5.0 (NO ₃ ) _1.0 ·0.7H ₂ O (Example 6). 10.0g of the compound obtained in Example 6 as NaCl
N containing 165ppm (12100ppm as chloride ion),
After adding to N-dimethylformamide 1 and stirring at 30°C for 1 hour, the chloride ion concentration in the supernatant was analyzed to determine the chloride ion removal rate. Similar tests were conducted on the compounds obtained in Comparative Examples 1 and 2 (Comparative Examples 5 and 6). These results are shown in Table 5.

[Table] Example 7, Comparative Examples 7 to 9 6 parts of the compound produced in Example 6, 75 parts of cresol novolac epoxy resin, brominated epoxy resin
25 parts of phenolic resin, 50 parts of phenolic resin, and 150 parts of fused silica were melt-blended and heat-cured at 170°C for 20 minutes. 10g of hardened material crushed and less than 100 mesh
was added to 100 ml of distilled water and heated at 151°C for 100 hours. After completion, the chloride ion concentration and bromide ion concentration in the supernatant liquid were measured (Example 7). A similar test was conducted without adding the compound obtained in Example 6 (Comparative Example 7). Separately, similar tests were conducted on the compounds obtained in Comparative Example 1 and Comparative Example 2 (Comparative Examples 8 and 9). The results of these tests are shown in Table 6.

[Table] (3) Effects of the invention Bi ₆ O ₆ (OH) _x (NO ₃ ) _6-x・nH ₂ O (however,
The bismuth compound represented by the formula (3.5≦x≦5.5, where n is 0 or a positive number) is a new compound that has a large anion exchange capacity and exchange rate near neutrality, and also has excellent water resistance, heat resistance, Because it has excellent hot water stability, it is used as an inorganic anion exchanger that can easily capture anions, which was previously difficult to do near neutrality, and can be widely used in fields that use ion exchange and adsorption. can.

Claims (1)

[Claims] 1 Bi ₆ O ₆ (OH) _x (NO ₃ ) _6-x・nH ₂ O (however, 3.5≦
A bismuth compound represented by the formula (x≦5.5, n is 0 or a positive number). 2 Bi ₆ O ₆ (OH) _x (NO ₃ ) _6-x・nH ₂ O (However, 3.5≦
An inorganic anion exchanger containing a bismuth compound represented by the formula (x≦5.5, n is 0 or a positive number) as an active ingredient.