JPH0249761B2 - KYUCHAKU SHORIHO - Google Patents

Description

[Detailed description of the invention]

The present invention is a liquid characterized by adding an acidic polysaccharide to a titanic acid dispersion liquid which has been subjected to adsorption treatment of unnecessary substances or valuables contained in the liquid using titanic acid powder to aggregate titanic acid. This invention relates to an adsorption treatment method. More specifically, titanic acid containing 0.01 to 1% of a water-insoluble aluminum compound is dispersed in a liquid to be adsorbed, and after adsorbing unnecessary substances or valuables, 0.1 to 1% of an acidic polysaccharide is added to the liquid to absorb titanic acid. The present invention relates to a liquid adsorption treatment method characterized by agglomerating liquids. Titanic acid is a titanium compound also called hydrous titanium oxide or hydroxide titanic acid, and depending on the chemical state of water, it can be divided into two types: orthotitanic acid and metatitanic acid.
It is said that there are different types. It is well known that all titanic acids belong to amphoteric compounds and are widely used as adsorbents. Furthermore, this titanic acid can selectively adsorb trace amounts of uranium in seawater, and it is thought that in the future nuclear reactor fuel will be provided by uranium recovered from seawater using titanic acid. Furthermore, wastewater from uranium mines contains highly concentrated radioactive elements such as radium and uranium, and the use of a titanic acid adsorbent in the treatment of such wastewater improves its treatment efficiency. Alternatively, in low-grade uranium mines, high-concentration uranium liquid is obtained using an in-place leaching method and uranium is extracted with high efficiency, but in this case as well, adsorption and recovery using titanic acid is said to be efficient. Ru. Furthermore, titanic acid has a high adsorption capacity for arsenic and is an effective adsorbent for treating arsenic-containing wastewater. Although titanic acid has a high adsorption capacity as mentioned above, its powder form makes it difficult to handle, and it is generally granulated to an appropriate particle size and packed in a column. used in However, since titanic acid has a reduced specific surface area due to its granulation and is affected by the molding agent, a reduction in adsorption capacity is unavoidable. The problem with handling powdered titanic acid lies in the recovery of titanic acid through adsorption treatment. In other words, if the titanic acid dispersed in the liquid to be adsorbed can be efficiently recovered, desorbed, and incorporated into a cycle for reuse, it is a desirable method that does not have the disadvantages of titanic acid granulation as described above. As a method, a titanic acid adsorbent dispersed in a liquid medium has been used by methods such as centrifugation, but these methods require a large amount of energy. Therefore, the inventors of the present invention conducted intensive studies on a method for efficiently recovering titanic acid from a treated liquid medium, and found that an acidic polysaccharide was added to the treated water in which powdered titanic acid containing a water-insoluble aluminum compound was dispersed. By doing so, the present invention was completed in which titanic acid is highly aggregated in the medium. This is due to the interaction between the water-insoluble aluminum compound contained in titanic acid and the acidic polysaccharide. The water-insoluble aluminum compound used in carrying out the present invention refers to aluminum-containing substances that are substantially insoluble in water, such as aluminum oxide and aluminum hydroxide. In carrying out the present invention, the aluminum compound may be contained in titanic acid in an amount of 0.1% or more. However, the amount added should be within a range that does not affect the adsorption properties inherent to titanic acid, and should preferably be suppressed to 1% or less. It is noteworthy that titanic acid containing 0.1 to 1% of a water-insoluble aluminum compound not only has its adsorption capacity not substantially reduced, but also that the dispersibility of powdered titanic acid in the water required for treatment is improved. Acidic polysaccharides used to aggregate titanic acid from water in which titanic acid is dispersed include agar,
Examples include alginic acid, carrageenan, pectin, guacam, and locust bean gum. These polysaccharides are easily insolubilized in aqueous media by interaction with water-insoluble aluminum compounds. Any of these polysaccharides can be used alone or in combination of two or more. In particular, carrageenan, especially carrageenan, which has good solubility or swelling property in water at room temperature and has a relatively low viscosity, easily aggregates with aluminum compounds and can be separated and recovered from water. Takara Keenan is effective. Carrageenan is a sulfate ester of galactan contained in red algae, and is broadly classified into Katupa carrageenan, Lambda carrageenan, and Iota carrageenan depending on the difference in sulfate group content and 3.6-anhydrogalactose content.These three types of carrageenan are physically The characteristics are different. In other words, Katupa carrageenan is poorly soluble in water at room temperature, and forms a strong gel by heating and dissolving it and then cooling it. Lambda carrageenan easily dissolves in water at room temperature and does not form a gel. Furthermore, iota carrageenan swells in water at room temperature and forms a weak gel when heated and dissolved and then cooled.
Although this is a general property, the properties of the soluble gel vary depending on the type of counter ion of the sulfuric acid residue. In other words, when sodium is present as a counter ion, katsupa carrageenan and iota carrageenan have high solubility in water at room temperature and do not form gels. In view of the above-mentioned solubility in water, it is effective to use lambda carrageenan, iota carrageenan, and katsupa carrageenan, sodium salt, as the polysaccharides used in the practice of the present invention. Another physical property characteristic of carrageenan is the viscosity of its aqueous solution. When 0.5% carrageenan is dispersed in water at room temperature, the viscosity at 25°C is 10 centipoise (CP) for Katupa carrageenan, 20 CP for iota carrageenan, and 150 CP for lambda carrageenan. Since lower viscosity is more effective in achieving the object of the present invention, katsupa carrageenan and iota carrageenan are preferred. The chemical properties of carrageenan include that it easily deteriorates under acidic conditions and is also rapidly decomposed by the action of oxidizing agents. These decompositions are accelerated by heating. This means that when adsorbed and recovered titanic acid is desorbed with acid and then activated, carrageenan is easily decomposed and titanic acid can be easily recovered. This is an advantageous point in its use. To carry out the present invention, titanic acid powder containing 0.01 to 1% of a water-insoluble aluminum compound is dispersed in water at a rate of about 1%, and 0.1 to 1% of carrageenan is added to the dispersion, stirred, and allowed to stand still. This can be carried out by precipitating titanic acid, and the sedimentation rate can be made extremely high compared to conventional methods. The present invention will be described in more detail below with reference to Examples. Example: One part of powder passed through a 320 mesh sieve with metatitanic acid containing 0.5% aluminum oxide was 99%
of water and stirred at 300 rpm for 30 minutes. After adding 0.5 part of the acidic polysaccharide shown in Table 1 to the dispersion and stirring at 300 rpm for 30 minutes, Table 1 shows the results of measuring the ratio of the volume occupied by the precipitated layer to the total volume after 30 and 60 minutes. It was shown to.

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Claims (1)

[Claims] 1 0.01 to 1% water-insoluble aluminum compound
The titanic acid powder contained therein is dispersed in a liquid to be adsorbed and the substance to be adsorbed is adsorbed, and then acidic polysaccharide is added to the liquid at a ratio of 0.05 to 1% to aggregate the titanic acid powder. Adsorption treatment method.