JPH03131349A - Granular inorganic ion exchanger - Google Patents

Abstract

PURPOSE:To obtain an inorg. ion exchanger enhanced in a high ion exchange characteristic, mechanical strength and heat resistance by baking a granular mixture containing metal alkoxide, a clay mineral and the inorg. ion exchanger. CONSTITUTION:An inorg. ion exchanger is an insoluble inorg. compound showing an ion exchanger characteristic in water, and any of a cation such as antimony trioxide, an anion such as lead hydroxyapatite and an amphoteric compound such as hydrated zironium hydroxide may be used. As a clay mineral, a hydrated silicate compound such as sepiolite is used. Metal alkoxide or a hydrolysate thereof, the clay mineral and the inorg. ion exchanger are mixed, kneaded, granulated and baked. The exchanger thus obtained becomes a uniform porous structure having a large surface area and is excellent in an ion exchange characteristic and enhanced in mechanical strength.

Description

Detailed Description of the Invention (a) Purpose of the Invention [Field of Industrial Application] The present invention provides a method for producing particulate inorganic ions that have excellent heat resistance, mechanical strength, and ion exchange properties and are useful for recovering impurities or valuable materials. Concerning exchange bodies.

[Prior art] Ion exchange resins are currently widely used as particulate ion exchangers, but ion exchange resins have a low heat resistance (
It has the disadvantage that it cannot be used at high temperatures (below 60°C).

On the other hand, compared to ion exchange resins, inorganic ion exchangers have superior stability at high temperatures or under bullet rays, and can be used for ion exchange treatment in high-temperature water, separation of bullet ray substances,
Applications such as concentration and purification are expected.

However, inorganic ion exchangers are generally obtained in the form of fine powder, so when using an inorganic ion exchanger in a column packing method, the fine powder of the inorganic ion exchanger is molded into an appropriate size and shape. It is necessary to reduce resistance to liquid passage, and it is also required to have sufficient mechanical strength to withstand operations such as backwashing and regeneration.

As a method of forming inorganic ion exchangers into granules, there is also a method of forming them using an organic binder such as cellulose or a synthetic polymer, but when an organic binder is used, the heat resistance of the granules is insufficient, and ion exchange treatment at high temperatures causes fusion and collapse between particles.

In order to fully utilize the heat resistance of inorganic ion exchangers, it is preferable to form them into granules using an inorganic binder, and conventional methods of forming them into granules using water glass or clay minerals have been known. There is.

However, in conventional granules obtained using inorganic binders, when the mechanical strength of the granules is increased, the ion exchange properties such as the ion exchange capacity and ion exchange rate of the inorganic ion exchanger are lower than that of the powder. It becomes impractical as an ion exchanger because the ion exchange properties of the granules are significantly reduced compared to those in the case of granules.
There is a problem that the mechanical strength does not reach a practical level,
It has not been possible to obtain a granular material that meets practical levels of heat resistance, mechanical strength, and ion exchange properties.

L Problems to be Solved by the Present Invention] The present inventors have solved the above-mentioned problems of conventional granular inorganic ion exchangers molded using an inorganic binder, and have improved heat resistance, mechanical strength, and ion exchangers. An object of the present invention is to provide a granular inorganic ion exchanger with excellent exchange characteristics.

(B) Structure of the invention [Means for solving the problem] As a result of intensive study, the present inventors found that as an inorganic binder,
By using clay minerals and metal alkoxides or their hydrolysates together, the above problems can be solved,
The inventors have discovered that it is possible to obtain an excellent granular inorganic ion exchanger, and have completed the present invention.

That is, the present invention is a granular inorganic ion exchanger obtained by firing a granular mixture containing a metal alkoxide or its hydrolyzate, a clay mineral, and an inorganic ion exchanger.

Hereinafter, each component in the present invention and a method for obtaining granules using them will be explained.

<Inorganic ion exchanger> The inorganic ion exchanger in the present invention is not particularly limited as long as it is an insoluble inorganic compound that exhibits ion exchange properties in water. For example, insoluble inorganic compounds that exhibit cation exchange properties include antimony dioxide, Antimony pentoxide, hydrated antimony (V) oxide, titanium antimonate, zirconium antimonate, tin antimonate, iron antimonate, aluminum antimonate, chromium antimonate, tantalum antimonate, manganese antimonate, bismuth antimonate, phosphorus antimonate , antimony tungstic acid, ammonium antimony molybdate,
Zirconium phosphate, bismuth phosphate, titanium phosphate,
Tin phosphate, vanadium pentoxide, hydrated vanadium pentoxide, titanium vanadate, aluminum vanadate, zirconium vanadate, phosphovanadic acid, vanadium molybdic acid, vanadium ferrocyanide, niobium pentoxide, hydrated niobium pentoxide, tantalum pentoxide, Hydrous tantalum pentoxide,
tantalum phosphate, ferrous hydroxide, aluminum hydroxide,
Manganese oxide [e.g. manganese nitrate (Mn(NOx)t)
6 HzO) at 150 to 190°C] contains hydrous manganese oxide and alkali metal ions or alkaline earth metal ions, and after firing at a high temperature, the alkali metal ions or alkaline earth metal ions are There are manganese compounds obtained by elution through treatment, and insoluble inorganic compounds that exhibit anion exchange properties such as lead hydroxyapatite, cadmium hydroxyapatite, hydrotalcite, bismuth trioxide, bismuth pentoxide, and hydrated bismuth oxide (■). , hydrated bismuth (V) oxide
and hydrous bismuth oxide nitrate (lit), and insoluble inorganic compounds exhibiting amphoteric ion exchange properties include hydrous zirconium oxide, hydrous titanium oxide, hydrous tin oxide, and hydrous lead oxide. Two or more of these compounds may be used as a mixture, if necessary.

The inorganic ion exchanger compound may have any structure, such as crystalline, amorphous, or glassy substances, and may have any form, but it may be in the form of powder, which is usually easily available. The particle size is preferably in the range of 0.01 to 100 μm, and more preferably in the range of 0.1 to 10 μm. The particle size is 0. If O is less than 1μ, the powders may aggregate or the surface of the powder may be covered with the binder.
There is a risk that the ion exchange properties will deteriorate, and on the contrary,
If it is larger, there is a fear that granules with high mechanical strength cannot be obtained because there are few contact areas with the binder.

Clay minerals> Clay minerals have a layered structure and have exchangeable ions such as alkali or alkaline earth metals between the layers, and clay minerals have a double-chain structure and have exchangeable ions between the layers. However, preferred clay minerals in the present invention are hydrated silicate-based compounds that have plasticity and exhibit shrinkage and increased mechanical strength upon drying or firing, such as These include sepiolite, which is classified as an inosilicate, and bentonite, kaolin, diatomaceous earth, kibushi clay, and frog's eye clay, which are classified as phyllosilicates.

When inosilicate is used as the clay mineral, thermal decomposition of the inorganic ion exchanger does not occur at all even when the granules are fired according to the process described below, and compared to the case of phyllosilicate, ion exchange Since it is possible to obtain a granular inorganic ion exchanger with excellent properties, especially ion exchange rate, ion exchange rate is one of the major factors that influences quality.
As the clay mineral used in the production of the granular inorganic ion exchanger, it is preferable to use inosilicate.

Examples of the inosilicate include palygorskite, apurgite, and sepiolite, and sepiolite is particularly preferred because of its high plasticity imparting ability. In addition, sepiolite is a clay mineral with a low desorption temperature of crystal water, and in general, if a clay mineral with a low desorption temperature of crystal water is used, a granular inorganic ion exchanger can be obtained by firing at a low temperature. The use of sepiolite is also advantageous.

The content of clay mineral is 100 parts by weight of inorganic ion exchanger (
It is preferably 1 to 70 parts, more preferably 2 to 40 parts. If the amount is less than 1 part, the mechanical strength of the granular inorganic ion exchanger will decrease, and if it is more than 70 parts, the effect of improving the mechanical strength will be small.
May cause deterioration of ion exchange properties.

<Metal alkoxide or its hydrolyzate> The metal alkoxide in the present invention is a compound in which the hydrogen of the hydroxyl group of an alcohol is replaced with a metal.
OR) a, T+ (OR) a, ^l (OR)
a and Zr(OR)n (R is an alkyl group such as methyl, ethyl, propyl, and butyl), and among these, silicon alkoxides have a lower hydrolysis rate than alkoxides of aluminum, titanium, zirconium, etc. is preferable because it can be easily made into a stable sol.

The metal alkoxide hydrolyzate in the present invention can be prepared by a conventional method [for example,
Mio Sakuko, “Sol-Gel Science J, pp. 8-24, published by Agne Seifu-sha (1988)], depending on the progress of the hydrolysis and polymerization reaction of the metal alkoxide in the solvent, sol or gel-like However, in order to facilitate kneading in the granulation step described later, it is preferable to use a sol-like material.

In the present invention, either a metal alkoxide or a hydrolyzate thereof may be used, but in order to shorten the kneading time in the granulation step described below, it is preferable to use a metal alkoxide hydrolyzate.

As the solvent for the above metal alkoxide, methanol,
Examples include alcohols such as ethanol, propatool and butanol, ethylene glycol, ethylene oxide, triethanolamine, xylene, formamide, dimethylformamide, dioxane and oxalic acid, and preferably al:1-ols are used.

The optimal blending amount of metal alkoxide or its hydrolyzate is
Although it varies depending on the type and amount of the inorganic ion exchanger and clay mineral used, per 100 parts of the inorganic ion exchanger,
The solid content of the metal alkoxide or its hydrolyzate (the amount converted to the weight of the metal oxide produced from the metal alkoxide) is 1 to 60 parts, preferably 1 to 30 parts, and more preferably 1 to 20 parts. It is better. When the amount is less than 1 part, the ion exchange properties of the particulate inorganic ion exchanger tend to decrease, and when it is more than 60 parts, the mechanical strength of the particulate inorganic ion exchanger tends to decrease.

<Molding method> In order to obtain the granular inorganic ion exchanger of the present invention, it may be molded through a -C molding process of blending, mixing/kneading, granulation, and firing.

First, the mixing/kneading process will be explained. In the mixing and kneading step, components such as an inorganic ion exchanger, a clay mineral, a metal alkoxide or a hydrolyzate thereof, and water are mixed.

The mixing order at this time is arbitrary, and each component may be mixed uniformly. An example of mixing/kneading operations is:
For example, the above-mentioned clay mineral is added to an inorganic ion exchanger, mixed uniformly with a kneader, etc., and then the above-mentioned metal alkali:
Oxide or its hydrolyzate and an appropriate amount of water may be added and wet-mixed. The water added at this time is a component added to facilitate mixing and kneading operations, and the amount of water added includes the type and particle size of the inorganic ion exchanger, the clay mineral and metal alkoxide, or the hydrolyzate thereof. Although it varies depending on the type and amount, it is usually 1 to 100 parts, preferably 1 to 50 parts, based on 100 parts of solid content in the slurry.

The slurry obtained in Part 2 is further kneaded using a kneader or the like for several hours to one day.

There are no particular restrictions on the granulation method, but it is preferable to use an extrusion granulation method, which has excellent yield and reproducibility on an industrial scale. In addition, it is preferable to size the obtained granules into spheres by a normal centrifugal rotation method or the like.

Thereafter, the sized granules are fired to impart sufficient mechanical strength to obtain the desired granular inorganic ion exchanger. The firing conditions at this time vary depending on the type and particle size of the inorganic ion exchanger, the type and amount of clay minerals and metal alkoxides or their hydrolysates, etc., but the maximum firing temperature during firing is usually 400 ° C or higher, The temperature is preferably lower than the melting point of the inorganic ion exchanger, and the maximum firing temperature is maintained for 1 to 8 hours, more preferably 2 to 6 hours. If the calcination temperature is less than 4QO'C, the mechanical strength of the granular inorganic ion exchanger will decrease, and if it is higher than the melting point of the inorganic ion exchanger, the particles will fuse to each other, or in some cases, the ion exchange properties will deteriorate significantly. There are cases.

There is no particular restriction on the rate of temperature increase during firing.

[Effect 1 2 Although the detailed mechanism is unknown, the presence of the metal alkoxide or its hydrolyzate suppresses the grain growth of the inorganic ion exchanger during calcination, and further reduces the volatile content of the metal alkoxide or its hydrolyzate. As a result of the volatilization of the granular inorganic ion exchanger during firing, the granular inorganic ion exchanger has a large specific surface area and a uniform porous structure, so it is thought that a granular material with excellent ion exchange properties and high mechanical strength can be obtained.

[Example and Comparative Example 1 Reference Example 1 First, a hydrolyzate of metal alkoxide' was prepared as follows.

That is, in a 300 m1 Mitsuro flask, a partial hydrolyzate of ethyl silicate [Tama Chemical Industry Product Name: Silicate 40140 g, ethanol 60 g, water 7.0 g
(theoretical amount of 120x necessary for hydrolysis) and 1.0 g of a strong acid type ion exchange resin (IR-120B-11 type) were mixed. Using a heating mantle, heat the mixture at 80°C for 2
After refluxing for a period of time, the mixture was cooled and the strong acid type ion exchange resin was removed by filtration. In this way, a silica sol (hydrolyzate of ethyl silicate) having a solid content (hereinafter abbreviated as Nv) of 15χ was prepared.

The present invention will be explained in more detail below using Examples and Comparative Examples.

Example 1 As an inorganic ion exchanger, 500 g of lead hydroxyapatite with an average particle size (value determined by a sedimentation method, hereinafter referred to as the value) of 0.7 μm, and 551 g of bentonite as a clay mineral. , 120 g of water and 560 g of the silica sol obtained in Reference Example 1 as a hydrolyzate of metal alkoxide.
g, and were mixed and kneaded in a kneader for 2 hours (rotation speed 10,100 rpm).

The above kneaded material was granulated using an extrusion granulator having two screw shafts and a screen of 0.511 χ mφ set on the lateral surface of the screw tip (screw rotation speed 20 rpm).
I11) Rod-shaped granules with a diameter of 0.5 mm were obtained.

The obtained rod-shaped granules were placed in a granulator having a rotating plate at the bottom of a cylindrical container, and the rotating plate was rotated at a speed of 700 rpm for 30 seconds to form particles by the rotational movement of the granules with collision with the side surface of the cylindrical container. I got something.

The obtained granules were fired in an electric furnace at 800°C for 2 hours and then cooled to obtain a granular inorganic ion exchanger having a particle size of 0.3 to 0.6 mm. The specific surface area of the granules measured by the BET method was 2.3 m27 g (see Figure 1).

0, IN of the granular inorganic ion exchanger thus obtained
The ion exchange capacity determined by 1ICI is 0.4 meq/
As a result of putting 1 g of the granular inorganic ion exchanger into a separatory funnel with 100 mL of water and shaking it 100 times/min, no crushing or powdering of the granular inorganic ion exchanger was observed.

In addition, 1.0 g of the obtained granular inorganic ion exchanger and 1/10
Mix 100ml of 0N HC + aqueous solution in a polyethylene container and shake with a shaker. Measure the shaking time and the amount of CL ions adsorbed on the granular inorganic ion exchanger to determine the ion exchange rate of the granular inorganic ion exchanger. evaluated.

The results are shown in Table 2.

Furthermore, the ion exchange capacity of the lead hydroxyapatite granular inorganic ion exchanger at temperatures of 60°C and 150°C was measured. The measurement conditions and measurement results at that time are shown in Table 3 below.

Example 2 Hydrotalcite with an average particle size of 7 μm was used as an inorganic ion exchanger, and the same particles as in Example 1 were prepared in the same manner as in Example 1 except that frog's eye clay was used. A particulate inorganic ion exchanger having the following diameter was obtained, and its ion exchange capacity and mechanical strength were evaluated, and the results are shown in Table I below.

Comparative Example 1 A particulate inorganic ion exchange product having the same particle size as in Example 1 was obtained in exactly the same manner as in Example 1 except that hentonite was not included. As a result of evaluating the mechanical strength of the obtained granular inorganic ion exchange in the same manner as in Example I, the granular inorganic ion exchange was crushed and powdered.

Comparative Example 2 A particulate inorganic ion exchanger having the same particle size as in Example 1 was obtained in exactly the same manner as in Example 1 except that no sorip sol was included. The specific surface area of the above granular material measured by the BET method was less than 0.1 m''/g (see Figure 2). The exchange capacity, mechanical strength, and ion exchange rate were evaluated, and the results are shown in Tables 1 and 2 below.

Example 3 As an inorganic ion exchanger, 500 g of potassium adsorbed on hydrous antimony (V) having an average particle size of 0.5 μm, 125 g of kaolin as a clay mineral, and 315 g of silica sol prepared in Reference Example 1 A granular material was obtained in the same manner as in Example 1 except that . Furthermore, the potassium contained in the obtained granules was reduced to 0. Ion exchange with protons was performed using IN11c+ to obtain a particulate inorganic ion exchanger having the same particle size as in Example 1.

The ion exchange capacity of the obtained granular inorganic ion exchanger was set to 0.
．． The mechanical strength was determined using 1N NaOH and evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

Comparative Example 3 A particulate inorganic ion exchanger having the same particle size as Example 1 was obtained in exactly the same manner as in Example 3 except that kaolin was not included. As a result of evaluating the mechanical strength of the obtained granular inorganic ion exchange in the same manner as in Example 1, the granular inorganic ion exchange was crushed and powdered.

Comparative Example 4 A granular inorganic ion exchanger having the same particle size as Example 1 was obtained in the same manner as in Example 3 except that silica sol was not included, and the ion exchange capacity and mechanical strength were evaluated.

The results are shown in Table 1 below.

Example 4 The same procedure was carried out except that as an inorganic ion exchanger, tin phosphate with an average particle size of 2.6 μm was adsorbed with sodium, hentonite was used as a clay mineral, and the firing time was 5 hours. A granular inorganic ion exchanger having the same particle size as Example 1 was obtained in the same manner as in Example 3, and the ion exchange capacity and mechanical strength were evaluated. The results are shown in Table 1 below.
It was shown to.

Example 5 The same procedure as in Example 3 was carried out, except that zirconium phosphate with an average particle size of 0.5 μm and adsorbed sodium was used as the inorganic ion exchanger, and frog's eye clay was used as the clay mineral. A granular inorganic ion exchanger having the same particle size as in Example 1 was obtained, and its ion exchange capacity and mechanical strength were evaluated. The results are shown in Table 1 below.

Example 6 The same procedure as in Example 5 was carried out, except that titanium phosphate with an average particle size of 0.7 μm and sodium adsorbed was used as the inorganic ion exchanger, and the particle size was the same as in Example 1. A granular inorganic ion exchanger was obtained, and its ion exchange capacity and mechanical strength were evaluated.

The results are shown in Table 1 below.

Example 7 The same particle size as in Example 1 was obtained in the same manner as in Example 5, except that zirconium phosphate with an average particle size of 0.5 μm and lithium adsorbed was used as the inorganic ion exchanger. A granular inorganic ion exchanger having the following properties was obtained, and its ion exchange capacity and mechanical strength were evaluated. The results are shown in Table 1 below.
It was shown to.

Example 8 As an inorganic ion exchanger, manganese dioxide was immersed in an aqueous magnesium chloride solution (IM) and dried.
After firing at 'C, 0. A granular inorganic material having the same particle size as in Example 1 was prepared in the same manner as in Example 3, except that an acid-treated manganese compound obtained by treatment with an IN hydrochloric acid aqueous solution was used, and Frog's eye clay was used as the clay mineral. An ion exchanger was obtained and its ion exchange capacity and mechanical strength were evaluated. The results are shown in Table 1 below.

Example 9 Using 15 g of sepiollie as a clay mineral and 50 g of the silica sol prepared in Reference Example 1, the firing temperature was set to 550.
A granular inorganic ion exchanger having the same particle size as in Example 1 was obtained in the same manner as in Example 1 except that the C5 firing time was changed to 4 hours. The obtained granular inorganic ion exchanger was evaluated for ion exchange capacity and mechanical strength, and the results are shown in Table 1 below.

Further, the ion exchange rate was evaluated in the same manner as in Example 1, and the results are shown in Table 2 below.

In addition, the powder X-ray diffraction diagram of the granular inorganic ion exchanger (Figure 3)
was exactly the same as the powder X-ray diffraction pattern (FIG. 4) of unfired lead hydroxyapatite.

Comparative Example 5 A granular inorganic ion exchanger was obtained in the same manner as in Example 4, except that hentonite was not included. As a result of evaluating the mechanical strength of the obtained granular inorganic ion exchange in the same manner as in Example 1, the granular inorganic ion exchange was crushed and powdered.

Comparative Example 6 A granular inorganic ion exchanger was obtained in the same manner as in Example 3 except that it did not contain silica sol, and its ion exchange capacity and mechanical strength were evaluated. Conclusion 23 (c) Effects of the Invention The granular inorganic ion exchanger of the present invention has significantly higher ion exchange properties, mechanical strength, and heat resistance than those formed into granules using conventional inorganic binders. has,
It is useful in various fields for water treatment such as recovering impurities and valuables.

[Brief explanation of the drawing]

FIG. 1 is a scanning electron micrograph of the granular inorganic ion exchanger obtained in Example 1, FIG. 2 is a scanning electron micrograph of the granular inorganic ion exchanger obtained in Comparative Example 2, and FIG. Granular inorganic ion exchanger powder X produced in Example 9
FIG. 4 is a powder X-ray diffraction diagram of unburned acid lead hydroxyapatite.

Claims (1)

[Claims] 1. A granular inorganic ion exchanger obtained by firing a granular mixture containing a metal alkoxide or its hydrolyzate, a clay mineral, and an inorganic ion exchanger.