REE speciation in low-temperature acidic waters and the competitive effects of aluminum
REE speciation in low-temperature acidic waters and the competitive effects of aluminum
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DOI：
10.1016/s0009-2541(99)00166-7
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发表时间：
2000-04
期刊：
影响因子：
3.9
通讯作者：
M. G. Serrano;Luis Francisco Auqué Sanz;D. Nordstrom
中科院分区：
文献类型：
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作者：
M. G. Serrano;Luis Francisco Auqué Sanz;D. Nordstrom
通过将 PHREEQE 代码应用于西班牙、巴西、美国和加拿大的水形态分析，评估了酸性水（pH 3.3 至 5.2）中溶解的稀土元素 (REE) 的同时竞争形态形成的影响。可能影响 REE 的主要离子是 Al3+、F−、SO42− 和 PO43−。氟化物通常是 REE 的重要络合剂，与酸性水中的 Al3+ 密切相关，因此对 REE 的影响很小。在酸性水的形态计算中包含铝浓度对于可靠的稀土元素形态至关重要。磷酸盐浓度太低（10−4 至 10−7 m），无法影响 REE 形态。因此，在这些条件下，SO42− 是 REE 唯一重要的络合配体。根据 Millero [Millero, F.J., 1992。作为离子强度函数的稀土无机复合物形成的稳定性常数。土石土。宇宙化学。 Acta, 56, 3123–3132]，随着原子序数的增加，镧系元素硫酸盐稳定常数几乎恒定，因此酸性水中的水络合不会导致稀土元素分馏。因此，稀土元素的富集或消耗必定是由传质反应引起的。
The effect of simultaneous competitive speciation of dissolved rare earth elements (REEs) in acidic waters (pH 3.3 to 5.2) has been evaluated by applying the PHREEQE code to the speciation of water analyses from Spain, Brazil, USA, and Canada. The main ions that might affect REE are Al3+, F−, SO42−, and PO43−. Fluoride, normally a significant complexer of REEs, is strongly associated with Al3+in acid waters and consequently has little influence on REEs. The inclusion of aluminum concentrations in speciation calculations for acidic waters is essential for reliable speciation of REEs. Phosphate concentrations are too low (10−4to 10−7m) to affect REE speciation. Consequently, SO42−is the only important complexing ligand for REEs under these conditions. According to Millero [Millero, F.J., 1992. Stability constants for the formation of rare earth inorganic complexes as a function of ionic strength. Geochim. Cosmochim. Acta, 56, 3123–3132], the lanthanide sulfate stability constants are nearly constant with increasing atomic number so that no REE fractionation would be anticipated from aqueous complexation in acidic waters. Hence, REE enrichments or depletions must arise from mass transfer reactions.