Abstract: Provided are a silicotitanate molded body having high strength and reduced generation of fine powder, a production method thereof, an adsorbent comprising the silicotitanate molded body, and a decontamination method of radioactive cesium and/or radioactive strontium by using the adsorbent. The silicotitanate molded body comprises: crystalline silicotitanate particles that have a particle size distribution in which 90% or more, on volume basis, of the particles have a particle size within a range of 1 ?m or more and 10 ?m or less and that are represented by a general formula of A2Ti2O3(SiO4).nH2O wherein A represents one or two alkali metal elements selected from Na and K, and n represents a number of 0 to 2; and an oxide of one or more elements selected from the group consisting of aluminum, zirconium, iron, and cerium.

Abstract: An adsorbent capable of adsorbing radioactive antimony, radioactive iodine and radioactive ruthenium, the adsorbent containing cerium(IV) hydroxide in a particle or granular form having a particle size of 250 ?m or more and 1200 ?m or less; and a treatment method of radioactive waste water containing radioactive antimony, radioactive iodine and radioactive ruthenium, the treatment method comprising passing the radioactive waste water containing radioactive antimony, radioactive iodine and radioactive ruthenium through an adsorption column packed with the adsorbent, to adsorb the radioactive antimony, radioactive iodine and radioactive ruthenium on the adsorbent, wherein the absorbent is packed to a height of 10 cm or more and 300 cm or less of the adsorption column, and wherein the radioactive waste water is passed through the adsorption column at a linear velocity (LV) of 1 m/h or more and 40 m/h or less and a space velocity (SV) of 200 h?1 or less.

Abstract: The present invention provides solidified radioactive waste into which a titanium-containing adsorbent having a radioactive element adsorbed thereto is vitrified, the solidified radioactive waste being capable of confining a large amount of the titanium-containing adsorbent having a radioactive element adsorbed thereto, and furthermore elution of the radioactive element from the vitrified waste being suppressed. The method of the present application includes a step of heat-melting a mixture that includes a titanium-containing adsorbent having a radioactive element adsorbed thereto, a SiO2 source, and an M2O source (M represents an alkali metal element) to form vitrified waste. The titanium-containing adsorbent is preferably one or two or more kind such as silicotitanate, an alkali nonatitanate, and titanium hydroxide.

Abstract: Provided are a silicotitanate molded body having high strength and reduced generation of fine powder, a production method thereof, an adsorbent comprising the silicotitanate molded body, and a decontamination method of radioactive cesium and/or radioactive strontium by using the adsorbent. The silicotitanate molded body comprises: crystalline silicotitanate particles that have a particle size distribution in which 90% or more, on volume basis, of the particles have a particle size within a range of 1 ?m or more and 10 ?m or less and that are represented by a general formula of A2Ti2O3(SiO4).nH2O wherein A represents one or two alkali metal elements selected from Na and K, and n represents a number of 0 to 2; and an oxide of one or more elements selected from the group consisting of aluminum, zirconium, iron, and cerium.

Abstract: The present invention provides solidified radioactive waste into which a titanium-containing adsorbent having a radioactive element adsorbed thereto is vitrified, the solidified radioactive waste being capable of confining a large amount of the titanium-containing adsorbent having a radioactive element adsorbed thereto, and furthermore elution of the radioactive element from the vitrified waste being suppressed. A method for producing solidified radioactive waste of the present invention is characterized by including heat-melting a mixture that includes a titanium-containing adsorbent having a radioactive element adsorbed thereto, a SiO2 source, and an M2O source (M represents an alkali metal element) to form vitrified waste, and the titanium-containing adsorbent is preferably one or two or more selected from silicotitanate, an alkali nonatitanate, and titanium hydroxide.

Abstract: An adsorbent capable of adsorbing radioactive antimony, radioactive iodine and radioactive ruthenium, the adsorbent containing cerium(IV) hydroxide in a particle or granular form having a particle size of 250 ?m or more and 1200 ?m or less; and a treatment method of radioactive waste water containing radioactive antimony, radioactive iodine and radioactive ruthenium, the treatment method comprising passing the radioactive waste water containing radioactive antimony, radioactive iodine and radioactive ruthenium through an adsorption column packed with the adsorbent, to adsorb the radioactive antimony, radioactive iodine and radioactive ruthenium on the adsorbent, wherein the absorbent is packed to a height of 10 cm or more and 300 cm or less of the adsorption column, and wherein the radioactive waste water is passed through the adsorption column at a linear velocity (LV) of 1 m/h or more and 40 m/h or less and a space velocity (SV) of 200 h?1 or less.

Abstract: The present invention provides a treatment method of radioactive waste water containing radioactive cesium and radioactive strontium, comprising passing the radioactive waste water containing radioactive cesium and radioactive strontium through an adsorption column packed with an adsorbent for cesium and strontium, to adsorb the radioactive cesium and radioactive strontium on the adsorbent, wherein the adsorbent for cesium and strontium comprises: at least one selected from crystalline silicotitanates represented by the general formulas: Na4Ti4Si3O16.nH2O, (NaxK(1-x))4Ti4Si3O16.mH2O and K4Ti4Si3O16.lH2O wherein x represents a number of more than 0 and less than 1, and n, m and l each represents a number of 0 to 8; and at least one selected from titanate salts represented by the general formulas: Na4Ti9O20.qH2O, (NayK(1-y))4Ti9O20.rH2O and K4Ti9O20.

Abstract: A treatment method of radioactive waste water containing radioactive cesium and radioactive strontium, comprising passing the radioactive waste water containing radioactive cesium and radioactive strontium through an adsorption column packed with an adsorbent for cesium and strontium, to adsorb the radioactive cesium and radioactive strontium on the adsorbent, wherein the adsorbent for cesium or strontium comprises a crystalline silicotitanate having a crystallite diameter of 60 ? or more and having a half width of 0.9° or less of the diffraction peak in the lattice plane (100), the crystalline silicotitanate represented by the general formula: A4Ti4Si3O16.nH2O.

Abstract: Provided is an adsorbent for removal of iodide ions and iodate ions, which exhibits excellent adsorption performance of iodide ions and iodate ions. An adsorbent according to the present invention comprises cerium(IV) hydroxide and a poorly soluble silver compound. It is preferable that the content of cerium(IV) hydroxide is 50% by mass or more and 99% by mass or less, and the content of the poorly soluble silver compound is 1% by mass or more and 50% by mass or less. It is also preferable that the poorly soluble silver compound is at least one selected from silver zeolite, silver phosphate, silver chloride, and silver carbonate.

Abstract: The invention provides an industrially advantageous method for producing a crystalline silicotitanate having high adsorption/removal capabilities for cesium and strontium in seawater. The method includes a first step of mixing a silicic acid source, a sodium compound, titanium tetrachloride, and water to prepare a mixed gel and a second step of hydrothermal reaction of the mixed gel prepared in the first step to produce crystalline silicotitanate of formula: Na4Ti4Si3O16.nH2O (wherein n represents 0 to 8). In the first step, the silicic acid source, sodium compound, and titanium tetrachloride are mixed in such a mixing ratio that the resulting mixed gel may have a Ti to Si molar ratio, Ti/Si, of 1.2 to 1.5 and an Na2O to SiO2 molar ratio, Na2O/SiO2, of 0.7 to 2.5.

Abstract: There are provided an adsorbent material excellent in the adsorptive removal properties of Cs and Sr also in seawater, and a method for producing a crystalline silicotitanate suitable for the adsorbent material. The adsorbent material according to the present invention comprises: at least one selected from crystalline silicotitanates represented by Na4Ti4Si3O16.nH2O, (NaxK(1-x))4Ti4Si3O16.nH2O and K4Ti4Si3O16.nH2O wherein x represents a number of more than 0 and less than 1 and n represents a number of 0 to 8; and at least one selected from titanate salts represented by Na4Ti9O20.mH2O, (NayK(1-y))4Ti9O20.mH2O and K4Ti9O20.mH2O wherein y represents a number of more than 0 and less than 1 and m represents a number of 0 to 10.

Abstract: There are provided an adsorbent material excellent in the adsorptive removal properties of Cs and Sr also in seawater, and a method for producing a crystalline silicotitanate suitable for the adsorbent material. The adsorbent material according to the present invention comprises: at least one selected from crystalline silicotitanates represented by Na4Ti4Si3O16.nH2O, (NaxK(1-x))4Ti4Si3O16.nH2O and K4Ti4Si3O16.nH2O wherein x represents a number of more than 0 and less than 1 and n represents a number of 0 to 8; and at least one selected from titanate salts represented by Na4Ti9O20.mH2O, (NayK(1-y))4Ti9O20.mH2O and K4Ti9O20.mH2O wherein y represents a number of more than 0 and less than 1 and m represents a number of 0 to 10.

Abstract: A method for producing a nonatitanate of an alkali metal, the method having: a first step for reacting an alkali metal hydroxide with titanium tetrachloride and producing Ti(OH)4; a second step for mixing the resulting Ti(OH)4 and an alkali metal hydroxide; and a third step for heating the mixture obtained in the second step, the alkali metal hydroxide being used so that the A/Ti molar ratio (A represents an alkali metal element) falls within a range of 1.0-5.0 in the second step, wherein a nonatitanate of an alkali metal can be produced economically.

Abstract: There is provided an adsorbent material having adsorptive removal properties of Cs and Sr in seawater, and a method for producing a crystalline silicotitanate suitable for the adsorbent material. The adsorbent material includes one selected from crystalline silicotitanates represented by Na4Ti4Si3O16.nH2O, (NaxK(1-x))4Ti4Si3O16.nH2O and K4Ti4Si3O16.nH2O wherein x represents a number of more than 0 and less than 1 and n represents a number of 0 to 8; and one selected from titanate salts represented by Na4Ti9O20.mH2O, (NayK(1-y))4Ti9O20.mH2O and K4Ti9O20.mH2O wherein y represents a number of more than 0 and less than 1 and m represents a number of 0 to 10. The adsorbent material is produced by a method for producing a crystalline silicotitanate in which a silicic acid source, a sodium compound and/or a potassium compound, titanium tetrachloride, and water are mixed to obtain a mixed gel, and the mixed gel is subjected to a hydrothermal reaction.

Abstract: There is provided an adsorbent material having adsorptive removal properties of Cs and Sr in seawater, and a method for producing a crystalline silicotitanate suitable for the adsorbent material. The adsorbent material includes one selected from crystalline silicotitanates represented by Na4Ti4Si3O16.nH2O, (NaxK(1-x))4Ti4Si3O16.nH2O and K4Ti4Si3O16nH2O wherein x represents a number of more than 0 and less than 1 and n represents a number of 0 to 8; and one selected from titanate salts represented by Na4Ti9O20.mH2O, (NayK(1-y))4Ti9O20.mH2O and K4Ti9O20.mH2O wherein y represents a number of more than 0 and less than 1 and m represents a number of 0 to 10. The adsorbent material is produced by a method for producing a crystalline silicotitanate in which a silicic acid source, a sodium compound and/or a potassium compound, titanium tetrachloride, and water are mixed to obtain a mixed gel, and the mixed gel is subjected to a hydrothermal reaction.

Abstract: The present invention relates to a polishing composition for a semiconductor wafer which is excellent in polishing property, and a polishing method. The polishing composition for a semiconductor wafer comprises colloidal silica consisting of non-spherical silica particles having a ratio of long axis to short axis of 1.5 to 15. The polishing method for a semiconductor wafer uses the polishing composition. The polishing composition can provide a remarkably high polishing rate compared with a polishing composition using spherical colloidal silica, and can provide good mirror-polishing without causing scratches. In addition, small alkali metal content enables reduction of adverse effects on a semiconductor wafer, such as residual abrasives after polishing.

Abstract: The present invention relates to a polishing composition for a substrate including a metal such as wiring, etc., formed on a semiconductor wafer, which can provide a high polishing rate without causing scratches on the wiring metal, a method of producing the polishing composition, and a polishing method. The polishing composition for a semiconductor wafer comprises an acid and an aqueous medium dispersion containing positively-charged silica particles having an amino group-containing silane coupling agent bonded on a surface thereof, the polishing composition having a pH of 2 to 6.

Abstract: The polishing compound for semiconductor wafer of the present invention contains colloidal silica composed of silica particles to which tetraethylammonium is fixed, and concentration of silica particles dispersed in water is between 0.5 to 50 weight %. Concentration of tetraethylammonium contained in silica particles to which tetraethylammonium is fixed is desirable to be in the range from 5×10?4 to 2.5×10?2 as indicated by molar ratio of tetraethylammonium/silica.

Abstract: The present invention relates to a polishing composition for a semiconductor wafer which is excellent in polishing property, and a polishing method. The polishing composition for a semiconductor wafer comprises colloidal silica consisting of non-spherical silica particles having a ratio of long axis to short axis of 1.5 to 15. The polishing method for a semiconductor wafer uses the polishing composition. The polishing composition can provide a remarkably high polishing rate compared with a polishing composition using spherical colloidal silica, and can provide good mirror-polishing without causing scratches. In addition, small alkali metal content enables reduction of adverse effects on a semiconductor wafer, such as residual abrasives after polishing.

Abstract: The present invention relates to a polishing composition for a substrate including a metal such as wiring, etc., formed on a semiconductor wafer, which can provide a high polishing rate without causing scratches on the wiring metal, a method of producing the polishing composition, and a polishing method. The polishing composition for a semiconductor wafer comprises an acid and an aqueous medium dispersion containing positively-charged silica particles having an amino group-containing silane coupling agent bonded on a surface thereof, the polishing composition having a pH of 2 to 6.