Thermodynamics studies of parameters involved in the formation of arsenic(V) precipitates with barium(II).

The arsenic presence in drinking water produces several problems in the hum an health, for that reason, it is of great interest to study chemical react ions, which allow to decrease its concentration in this resource. In the present work, the stoichiometry and conditional solubility product w as determined. Precipitation reactions between Ba (II) and As(V), as functi on of the pH, and the initial concentration of arsenic, were also studied. The major products found in the precipitate obtained at pH =9.25 and 12.75, were identified as BaHAsO4 . H2O and Ba-3(AsO4)(2) respectively, by powder X-ray diffraction. Conditional solubility products of 9.8 +/- 0.3 and 19.3 +/- 0.2 were found at pH =9.25 and 12.75, respectively.