JPS602101B2 - Manufacturing method of inorganic anion exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an inorganic anion exchanger suitable for the exchange of polyvalent anions.

In recent years, from the perspective of environmental purification or the effective use of resources, especially underground resources and marine resources, treatment of water containing harmful substances such as arsenic and chromium, or water containing valuable substances such as uranium, has become increasingly important. Technologies are being developed to efficiently concentrate and recover substances.

The above substances usually contain arsenate ions, arsenate ions, chromate ions, uranyl carbonate, uranyl sulfate, etc. in water.
Since it exists as a polyvalent anion, it is conceivable to use an anion exchange resin for processing, concentration, recovery, etc. However, anion exchange resins do not have sufficient selectivity for these polyvalent anions, and in systems where large amounts of monovalent anions such as chloride ions and bromide ions coexist, the exchange capacity for polyvalent anions is significantly reduced. Furthermore, ion exchange resins also have drawbacks such as lack of stability under high temperatures and strong radiation. On the other hand, inorganic anion exchangers have superior stability at high temperatures and under strong radiation compared to ion exchange resins.
It can be expected to be applied to water treatment at high temperatures, separation, concentration, and purification of highly radioactive substances.

However, in general, inorganic anion exchangers have a small exchange capacity, low chemical stability such as relatively high solubility in acidic or alkaline conditions, and when made into granular products for the purpose of using in a column method, etc. However, it has drawbacks such as low mechanical strength, especially in water. The purpose of the present invention is to produce an inorganic anion exchanger capable of efficiently exchanging polyvalent anions such as arsenic, chromium, and uranium, especially under high temperature conditions and under conditions where a large amount of monovalent anions coexist. Our goal is to provide the following.

The gist of the present invention is to provide an alumina sol containing 30 to 9 parts by weight of at least one hydrated oxide of an element selected from the group consisting of titanium, zirconium, and thorium, and 70 to 2 parts by weight as an alumina component. Alternatively, alumina gel or further mixed with 0-1 to 10 parts by weight of an inorganic acid in the presence of 20 to 50 parts by weight of water based on 100 parts by weight of the total amount of the hydrated oxide and alumina component. A method for producing an inorganic anion exchanger characterized by extrusion granulation followed by drying.

The hydrated oxides of titanium, zirconium and thorium used in the present invention include Ti02.nH20, Z2.
It is represented by a chemical formula such as nH20, Tho2.NH20, etc., and those in which n=2.0 to 0.5 are usually used.

In addition, the alumina sol or alumina gel used in the present invention has particles with an average size of 1 in the length direction.
The main component is colloidal alumina with an average diameter of about 10 mm and a water content of 90 to 80% based on the alumina content of 10 to 20%. In the present invention, 30 to 9 parts by weight of at least one of the above hydrated oxides and 70 parts by weight as an alumina component are used.
~2 parts by weight of alumina sol or alumina gel, more preferably 50 to 95 parts by weight of the hydrated oxide and 50 to 5 parts by weight of alumina sol or gel as the alumina component.

If the amount of the hydrated oxide is less than 3 parts by weight, the ion exchange capacity of the resulting ion exchanger will be insufficient, and if the alumina component is less than 2 parts by weight, the strength of the ion exchanger particles, especially the strength in water, will be significantly reduced. decreases significantly. Moreover, in the present invention,
In addition to the above hydrated oxide and alumina component, 0.1 inorganic acid is added.
~1 part by weight may be added.

Examples of the inorganic acid used include hydrochloric acid, sulfuric acid, nitric acid, etc., but it is not preferable to use phosphoric acid. The anion exchange capacity of the anion exchanger obtained in the present invention is further increased by the addition of the above-mentioned inorganic acid, but this effect becomes remarkable when it is added in an amount of 0.1 part by weight or more.
Even if the weight part exceeds , no further effect is observed, and rather undesirable phenomena such as a drastic drop in the pH of the treated water occur. In the present invention, the above hydrated oxide,
When adding alumina sol or alumina gel and an inorganic acid, a predetermined amount of the above inorganic acid is sufficiently moated using a patch type or continuous mixer.

During kneading, it is necessary that 20 to 50 parts by weight of water be contained per 10 parts by weight of the solid content consisting of the waterborne oxide and the alumina component. If the water content is less than 2 parts by weight, it will turn into powder during extrusion granulation, making it impossible to obtain an ion exchanger with the desired strength and particle size, and if it exceeds 50 parts by weight, particles will adhere to each other during extrusion granulation. etc., making the granulation operation difficult. Normally, this water is supplied from alumina sol or alumina gel, but if water is insufficient, water is supplied during kneading. The kneaded material is then passed through a die or screen into a screw-type extrusion granulator,
Extrusion granulation is performed using a roll-type extrusion granulator, a blade-type extrusion granulator, etc. to form granules. The average particle size of the granules can be controlled by appropriately selecting the pore size of the die or screen of the extruder. When the inorganic anion exchanger of the present invention is used in a so-called packed column system in which the inorganic anion exchanger is packed in a packed column and water is passed through it, it is preferable that the average grain size is 0.1 to 5 cells. Next, the anion exchanger of the present invention is obtained by air-drying or heat-drying the extruded granules as described above. When performing heat drying, the heating temperature is 300
qo or less is preferable. When the heating temperature exceeds 300 oo, undesirable phenomena such as a decrease in the ion exchange capacity of the obtained ion exchanger occur. In addition to the characteristics of general inorganic ion exchangers such as excellent stability at high temperatures, the inorganic ion exchanger obtained by the present invention has extremely excellent selective exchange ability for polyvalent anions, and has a pH of 9 or less. It has a large anion exchange capacity over a wide pH range.

Furthermore, the solubility in a wide pH range is 4.0, and the particles have a high strength in water. The ion exchanger of the present invention has hydrated oxides of elements such as titanium, zirconium, and thorium, which have excellent selective ion exchange ability and exchange capacity for polyvalent anions, and fine particles of these hydrated oxides. As mentioned above, since the alumina sol or alumina gel consisting of very fine particles on the order of millimicrons is held and fixed in a suitably condensed state, the structure has high strength in water and the surface of the hydrated oxide fine particles can be effectively utilized. It becomes.

As mentioned above, the alumina component, which is a component of the ion exchanger obtained by the present invention, plays a role in binding the hydrated oxide fine particles.

Other possible binders include inorganic binders such as silica sol, sodium silicate, and phosphoric acid, and organic binders such as cellulose and synthetic polymers. However, organic binders are insufficient in terms of heat resistance, acid resistance, and alkali resistance, and particles disintegrate when treated at high temperatures or when recycled with strong alkalis.
Furthermore, when silica sol, sodium silicate, phosphoric acid, etc. are used, the constant dew point of the resulting ion exchanger becomes low and anion exchange ability is lost in regions other than strongly acidic regions. By further adding an inorganic acid to the constituent components of the ion exchanger obtained in the present invention, the anion exchange ability can be further increased.

The inorganic acid contained in the ion exchanger increases the proton concentration near the surface of the ion exchanger in water, and as a result, the number of exchange groups in the anion exchanger of the present invention increases and the anion exchange capacity increases. The inorganic anion exchanger obtained by the present invention has particularly excellent selective exchange ability for polyvalent anions, and examples of these polyvalent anions include arsenate ion, arsenite ion, chromate ion, and phosphate ion. , uranyl carbonate, uranyl sulfate, molybdate ion, tungstate ion, vanadate ion, etc., and in particular, removal of the above polyvalent anions coexisting with large amounts of chlorine ion, bromide ion, etc.
Effective for concentration and recovery.

Since the inorganic anion exchanger obtained by the present invention has excellent strength in water and stability in a wide range of pH range, it can be regenerated and backwashed in the same manner as ordinary ion exchanger=oku resin.

As a regenerating agent, sodium hydroxide, potassium hydroxide,
Use sodium carbonate, aqueous ammonia, etc. Methods for removing harmful substances or concentrating and recovering valuable substances using the inorganic anion exchanger obtained in the present invention include:
A so-called slurry method is used in which an inorganic anion exchanger is suspended and dispersed in water containing harmful or valuable substances and then filtered.

It is also possible to use a column system in which water containing harmful or valuable substances is passed through a packed column filled with an inorganic anion exchanger. The inorganic anion exchanger of the present invention can be used for separating and removing arsenic contained in groundwater, ore processing wastewater, etc., recovering chromium from plating wastewater, etc. by utilizing the above-mentioned characteristics. The details of the present invention will be shown below using Examples. Example 1 200 parts by weight of alumina sol (2 parts by weight as the alumina component) was added to 80 parts by weight of each of the hydrated oxide of titanium (Ti02/ratio 0) and the hydrated oxide of zirconium (Z2/QO). Add and knead thoroughly using a kneader.

After kneading, the mixture was molded into granules by passing through a die with a diameter of one side using a screw-type extrusion granulator.
Next, the molded product was dried in hot air at 10,000 °C for 1 hour to obtain a particulate inorganic anion exchanger. An arsenic acid aqueous solution containing 5 ppm of arsenic (LOOO) was placed in an Erlenmeyer flask, 0.100 g of the above inorganic anion exchanger was added thereto, and the flask was left standing at 25° C. overnight while shaking.

Arsenic concentration in the resulting toplight solution (arsenic concentration in treated water)
Table 1 shows the equilibrium adsorption amount of arsenate ion calculated based on this result. Table 1 and Table 2 show the isotonic points of the above inorganic anion exchangers determined by the titration method.

Table 2 Example 2 The precipitate obtained by adding a large excess of ammonia water to an aqueous solution of thorium nitrate (Th(N03) 4.4 days 20) was washed with water and then dried at 30 qo for 2 hours. The hydrated oxide of thorium (Tho2.1
．． Group 20) 28 parts by weight of alumina gel (5 parts by weight as the alumina component) were added to 50 parts by weight to obtain an inorganic ion exchanger in the same manner as in Example 1.

As a result of performing the same test method as in Example 1 on this inorganic ion exchanger, the arsenic concentration in the treated water was 1.31 ppm.
The equilibrium adsorption amount of arsenate ion was 37 mol/night as arsenic.

Comparative Example 1 10 parts by weight of silica sol (20 parts by weight as silica) was added to 8 parts by weight of hydrated oxide of titanium (Ti02/ratio ○), and in the same manner as in Example 1, an average particle size of 1 willow was added. Particulate matter was obtained.

An arsenic acid aqueous solution of 5 ppm as arsenic was placed in an Erlenmeyer flask, 100 g of the particulate matter obtained as described above was added thereto, and the mixture was left overnight at 260 ℃ while holding a light. Table 3 shows the equilibrium adsorption amount of arsenate ion.

Also shown is the isometric point determined by the bottle method for the particulate matter mentioned above.
Table 3 As mentioned above, the granules obtained by using silica sol instead of the alumina sol used in Example 1 have a lower isoelectric point than the inorganic anion exchanger of the present invention obtained in Example 1, The equilibrium adsorption amount of arsenate ions is also extremely low. Example 3: 90 parts by weight of hydrated oxide of titanium (Ti02, ○), 56 parts by weight of alumina gel. Example 1
Extrusion granulation and drying were performed in the same manner as above to obtain a particulate inorganic anion exchanger.

5 ppm arsenic acid aqueous solution 100 as arsenic in an Erlenmeyer flask
0' and add 0.10 of the above inorganic anion exchanger to this.
After adding 0.0 ml of water, the mixture was left at 25° C. overnight with a light on. Table 4 shows the equilibrium adsorption amounts of arsenate ions obtained as a result. Table 4 Example 4 Extrusion granulation and drying were performed in the same manner as in Example 1 using hydrated titanium oxide, alumina component of alumina gel, and water in the proportions shown in Table 5, and the average particle diameter obtained was The equilibrium adsorption amount of arsenic acid obtained under the same conditions as in Example 1 using the granules of 1 skin was calculated as
Shown in the table.

Separately, the granulated material was packed into a column with a diameter of 5 mm and a length of 120 mm to a packing length of 60 mm, and backwashed and fluidized for 4 hours at an upward flow rate of 30 m/day. After washing the granules with water on a 32 mesh sieve and removing the crushed powder,
After drying at 0 for 1 hour, the weight was measured, divided by the initial filling weight, multiplied by 100, and the value was taken as the recovery rate (%) and used as a guideline for underwater strength. Table 5 Examples shown in Table 5 5 Extrusion granulation and drying were carried out under the same conditions as in Example 1, using a hydrated titanium oxide, the alumina component of the alumina gel, and water in the proportions shown in Table 6.

If a granulated product is obtained, take 0.100 g of this granulated material into an Erlenmeyer flask and add 5 ppm of arsenic acid and 100 g of this granulated material as arsenic.
Take 1,000 ml of water containing 0 pm of sodium chloride, keep it at 25°C under a light, and leave it overnight. Table 6 shows the equilibrium adsorption amount of arsenate ions calculated from the arsenic concentration of the resulting supernatant (arsenic concentration of treated water). Table 6 also shows the moldability during granulation. Table 6

Claims (1)

[Scope of Claims] 1. At least one hydrated oxide of an element selected from the group consisting of titanium, zirconium, and thorium 30 to 98
parts by weight and 70 to 2 parts by weight of alumina sol or alumina gel as an alumina component are kneaded in the presence of 20 to 50 parts by weight of water based on 100 parts by weight of the total amount of the hydrated oxide and alumina component. A method for producing an inorganic anion exchanger, which comprises extrusion granulation and drying. 2 At least one type of hydrated oxide of an element selected from the group consisting of titanium, zirconium, and thorium 30 to 98
parts by weight, 70 to 2 parts by weight of alumina sol or alumina gel and 0.1 to 10 parts by weight of an inorganic acid as the alumina component, and the total amount of the hydrated oxide and alumina component is 100 parts by weight.
A method for producing an inorganic anion exchanger, which comprises kneading in the presence of 20 to 500 parts by weight of water, extrusion granulation, and drying.