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oai:docta.ucm.es:20.500.14352/340832023-08-26T01:28:29Zcom_20.500.14352_14col_20.500.14352_15

Rosenberg, Yoav O. Sadeh, Yonatan Metz, Volker Pina Martínez, Carlos Manuel Ganor, Jiwchar 2023-06-19T13:35:28Z 2023-06-19T13:35:28Z 2014 0016-7037 10.1016/j.gca.2013.09.041 https://hdl.handle.net/20.500.14352/34083 https://www.sciencedirect.com/science/article/pii/S0016703713005504 Co-precipitation of Ra and Ba in barite (i.e., the formation of a RaxBa1-xSO4 solid solution) has long been established as an important process that has the potential to control Ra concentration. This process is commonly described by a distribution model. Ample studies have shown that the key parameter of this model, the partition coefficient, varies in the range of 1–2 as a function of temperature, salinity and precipitation kinetics of the RaxBa1-xSO4 solid solution. This roughly twofold change in the partition coefficient may lead to large differences in the concentration of dissolved Ra. The present study systematically investigated the co-precipitation kinetics of the RaxBa1-xSO4 solid solution from aqueous solutions up to 5.9 mol kg-1 H2O NaCl, circum-neutral pH and at ambient temperature. Laboratory batch experiments designed to follow the nucleation of the RaxBa1-xSO4 solid solution and the co-precipitation kinetics of Ba and Ra from aqueous solutions which were initially supersaturated with respect to barite (degree of supersaturation, ßbarite = 20 ± 2). The following empirical law describes the dependence of the activity-based partition coefficient, K¨D,barite, on the degree of supersaturation, ßbarite: = 20 ± 2). K¨D,barite =(199 ± 0,05) - (0,58 ± 0,06)log(ßbarite). This empirical law is in good agreement with other literature data. The outcomes of the empirical law are compared to the prediction of a model for the nucleation of two-dimensional islands. eng https://creativecommons.org/licenses/by-nc-nd/3.0/es/ open access Atribución-NoComercial-SinDerivadas 3.0 España Nucleation and growth kinetics of RaxBa1-xSO4 solid solution in NaCl aqueous solutions journal article