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Determination of inhibition kinetics of trace cerium

L, H ... O0.010, NaOH: 2.0X10_. mo1. / L, 5Occ. The linear range of 0.04 ~ 0.44mg / L, detection limit of 0.02mg / L. When the solution of the cerium content of 0.16mg / L, the 3 to 8 times the amount of light rare earth, 5 ~ ¨ times the amount of heavy rare earth and the most with the times do not interfere with the determination of uranium and thorium. 2 Experimental Part 2. Cerium reagents and equipment I (_) standard solution: 2omg/Lf salicylfluorone (SAF) ethanol solution: 1.0X10mol / L; HO solution 0.3sNaOH solution {0.5mo / / L; 722 type spectrophotometer ~ WC/09-05 Super Thermostat {pHT-P-type pH meter. 2.2 The test method in the two 25mL ethyl engraved Yu colorimetric tube, followed by addition of the aforementioned concentration SAF1.0mL, H2Oz0.8mL and NaOH solution, 1.0mL, again a cuvette which was added a certain amount of Ce (1) standard solution, the other without; rejection of distilled water and diluted to the mark and shaken, the reaction temperature in the s0c 3rain, quickly removed,[link widoczny dla zalogowanych], water cooling 10rain after the steaming water as the reference value, was measured at a wavelength of 520tim reagent () and test solution absorbance () to obtain the difference between the two AA = A - Ao3 Results and discussion 3. I absorption wavelength of 510 ~ 530nm wavelength range, inhibition of a non-suppression system, the larger the absorbance difference AA, choose the detection wavelength 520nm. Experiments show that the pH 3-2 solution! Ce shaking HO-SAF redox reaction in alkaline medium can be a very good manner. Test the influence of different concentrations of NaOH, NaOH concentration found in 0.02mol / L the vicinity of the reaction system suppressed and non suppressed the maximum absorbance of the whole. Select NaOH concentration 0.020mol / L. 3-3SAF concentration of 2.8 ~ 5.6 × 10mol / L range, △ A increases with the concentration of SAF, but the system stability was reduced and reproducible method of variation I take into account the sensitivity and reproducibility Select a SAF concentration of 4.0X10 mot / L. 3.4H: O the concentration of H: Oz concentration in the range of 0.004 ~ 0.012, inhibition of a non-suppression of absorbance difference △ with H0. Changes in the concentration range of small, almost constant. However, HO: concentrations exceeding 0. O12 later. Absorbance difference decreasing. Choose the last solution, this concentration of 0.010 H2. 3. s temperature of the reaction temperature and reaction time in the '0 ~ 60 After more than 70U, Ce (I) of the inhibitory effect decreased,[link widoczny dla zalogowanych], △ t and the temperature dropped,[link widoczny dla zalogowanych], it can lead Hz decomposition reaction temperature selected 50 In these conditions, the reaction of 2 ~ 5mm high sensitivity, △ A choice reaction time is almost constant 3rain, water cooling 10rain terminate the reaction. 3.6 The concept of activation energy and reaction order atlas to lnAA ~ I / T diagram obtained by the apparent activation energy for the 28.75kJ/tool. As addition to ce (Ⅲ) reagents than overdose, ignoring its concentration, its concentration can be directly merged into the constant term. Also at the initial stage, △ A and time is proportional to that of the inhibitory agent Ce (I) should be a reaction kinetic equation: d ['SAF] / dt =-- k. Ice] 3.7 working curve 0. o4 ~ o. 44mg / L range of cerium concentration and △ A good linear regression equation is: △ one 0.8810C (mg / L) +0.0349,09938 t to 3 times the standard deviation of the blank count determined the detection limit of 0.02mg / L} containing 0.2mg / L Ce (Ⅱ) Determination of 6 the solution, the average recovery was 97.6. RSD relative standard deviation was 2.1. 3-8 when the solution containing ions of Ce 0-16mg / L, the error range of ± 5, 3 to 8 times the amount of light rare earth, 5 ~ ¨ times the amount of heavy rare earth elements do not interfere , general sample does not exceed the amount of rare earth co-exist. Direct determination of expected samples without separation of cerium. 3.9 Samples given by my homemade guillotine Bastnaesite and major ion adsorption-type REE ore and any proportion of the amount of Ce (I) with the rest of synthesized samples obtained by mixing the rare earth ions, the appropriate method diluted the wet car l be cerium content,[link widoczny dla zalogowanych], the recovery was 95.4 ~ 103.4, and the relative standard deviation of 1.5% -2.8%. 1999-07-08 lotus collection} 1996-10-15 acceptable.
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