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Radiochemical Methods
Published in Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus, Environmental Chemical Analysis, 2018
Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus
The above procedure, however, would not apply if only strontium-90 is to be measured and not the total strontium activity in the sample. This is due to the fact that both the radionuclide of strontium, namely, 90Sr and 89Sr cannot be separated by precipitation method or by any other chemical process because their chemical properties are similar. The amount of 90Sr in the sample is determined by separating its daughter isotope yttrium-90 and then measuring the latter's activity. It may be noted that the activity of 90Sr is exactly equal to the activity of 90Y after the equilibrium is reached. Yttrium-90 is separated by acidifying the sample with concentrated nitric acid and then extracting the solution with tributyl phosphate. Yttrium-90 is then back extracted into dilute nitric acid and the solution is evaporated to dryness for beta counting. An alternative method consists of adding yttrium carrier and ammonium hydroxide to the sample. Yttrium hydroxide, Y(OH)3 precipitate is centrifuged and separated, washed, and converted into yttrium nitrate by treatment with nitric acid. The water-soluble yttrium nitrate is dissolved in water and treated with oxalic acid to precipitate out yttrium oxalate. The precipitate is washed successively with water, 95% ethanol, and diethyl ether and air dried. It is then weighed, mounted on a nylon disk, covered with polyester plastic film, and counted in an internal proportional or end-window counter to measure the beta activity of 90Sr. The activity is measured as follow: S90,pCi/L=net cpm/2.22abcdfg where a is the counting efficiency for 90Y, b the chemical yield of precipitating 90Y, c the in-growth correction factor, d the chemical yield of strontium, f the sample volume, L, and g is the decay factor for 90Y, which is determined from e−(0.693/T½)t (the half-life, T1/2 for 90Y is 64.2 h and t is the time in hour between the separation and counting).
Influences of TiO2 or Y2O3 doping on the homogeneity of polycrystalline Al2O3 produced by pulsed electric current sintering
Published in Journal of Asian Ceramic Societies, 2021
Huu Hien Nguyen, Takashi Shirai, Yuzin Xin, Quoc Khanh Dang, Makoto Nanko
The precursor for Y2O3 dopant, yttrium nitrate Y(NO3)3.10H2O (Wako Pure Chemical Industries, Ltd.), was mixed with Al2O3 powder in distilled water at the concentration of 0.1 mol% of Y2O3, followed by ball milling for 1 d. The aqueous solution was calcined in air at approximately 400°C for 2 h. The dried powder was milled manually by a mortar and a pestle. Because of the strong agglomeration in Y2O3-doped powder after the calcination, the powder was treated with polyethylene glycol (PEG) as a dispersant. 4 mass% of PEG was mixed with the Y2O3-doped Al2O3 powder in distilled water and the slurry was ball-milled for 1 d. The slurry was dried in air at 120°C in 12 h. After manual milling by a mortar and a pestle, annealing process was conducted at 600°C for 2 h to reject CO2 and H2O from the PEG dispersant. The TS-PECS was conducted similarly to the undoped Al2O3 powder. The sintering temperature for Y2O3-doped Al2O3 powder varied from 930 to 1150°C in the first holding step and from 1130 or 1350°C in the second holding step. Other conditions of the TS-PECS process were the same. Table 1 summaries the sintering temperatures of PECS processes for all three powders and the notations of samples.
Novel magnetic gel composite based on sodium alginate crosslinked by Yttrium(III) as biosorbent for efficient removal of direct dyes from aqueous solution
Published in Journal of Dispersion Science and Technology, 2021
Through detailed exploration, the optimized preparation scheme of Fe3O4@SA/Y polymer gel beads was as follows (Figure 2): 3.0 g SA powder was dissolved in 100 mL deionized water with constant agitation at room temperature. The uniformly dispersed 3 g/L Fe3O4 solution was added to the 30 g/L SA solution, stirred evenly and then dispersed by ultrasound for 30 min. The resulting mixture was dripped into 35 g/L yttrium nitrate solution by means of a syringe at 25 °C, and the black spherical gel beads were formed by cross-linking polymerization between Y(III) ions and SA molecules. After keeping solidification for 180 min, the polymer gel beads were taken out from the solution, washed and dried, and finally the target product Fe3O4@SA/Y biosorbent was obtained.