Search Results

You are looking at 1 - 2 of 2 items for

  • Author or Editor: A. Rojas-Hernández x
  • Refine by Access: All Content x
Clear All Modify Search
Journal of Radioanalytical and Nuclear Chemistry
Authors: H. López-González, M. Jiménez-Reyes, M. Solache-Ríos, and A. Rojas-Hernández

Abstract  

Solubility product (Lu(OH)3(s)⇆Lu3++3OH) and first hydrolysis (Lu3++H2O⇆Lu(OH)2++H+) constants were determined for an initial lutetium concentration range from 3.72·10−5 mol·dm−3 to 2.09·10−3 mol·dm−3. Measurements were made in 2 mol·dm−3 NaClO4 ionic strength, under CO2-free conditions and temperature was controlled at 303 K. Solubility diagrams (pLuaq vs. pC H) were determined by means of a radiochemical method using 177Lu. The pC H for the beginning of precipitation and solubility product constant were determined from these diagrams and both the first hydrolysis and solubility product constants were calculated by fitting the diagrams to the solubility equation. The pC H values of precipitation increases inversely to [Lu3+]initial and the values for the first hydrolysis and solubility product constants were log10 β* Lu,H = −7.92±0.07 and log10 K*sp,Lu(OH)3 = −23.37±0.14. Individual solubility values for pC H range between the beginning of precipitation and 8.5 were S Lu3+ = 3.5·10−7 mol·dm−3, S Lu(OH)2+ = 6.2·10−7 mol·dm−3, and then total solubility was 9.7·10−7 mol·dm−3.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Ramírez-García, M. Jiménez-Reyes, M. Solache-Ríos, E. Fernández-Ramírez, H. López-González, and A. Rojas-Hernández

Abstract  

The solubility of europium at 0.02M, 0.1M and 0.7M NaClO4 ionic strength solutions was determined by a radiometric method and pEus-pCH diagrams were obtained. Hydrolysis constants were also determined at the same ionic strengths by pH titration and the values found were log * 1 = -7.68±0.11, -8.07±0.10 and -8.20±0.11. The log K sp values were -23.5±0.2, -22.7±0.2 and -21.9±0.2 for 0.02M, 0.1M and 0.7M NaClO4 ionic strengths, respectively, at 303 K under CO2-free conditions and the extrapolated value at zero ionic strength was log K sp 0 = -24.15. The working pCH ranges for the calculation of the hydrolysis constants were selected from the pEus-pCH diagrams in the region where precipitation of europium oxide or hydroxide was less than 20%. Europium removal from aqueous solutions with zeolites was explored.

Restricted access