Department of Soil Science and Soil Protection, Czech University of Life Sciences Prague, Kamýcká 129, 16521 Praha 6, Czech Republic.
J Hazard Mater. 2010 Apr 15;176(1-3):913-8. doi: 10.1016/j.jhazmat.2009.11.123. Epub 2009 Nov 27.
This work focused on the specific behavior of Tl-bearing phases in the BCR (Community Bureau of Reference) sequential extraction (SE) scheme, namely Tl-bearing ferrihydrite, goethite, birnessite, calcite, illite, sphalerite and feldspar in their simple model mixtures with quartz. Several significant discrepancies between the obtained and expected behaviors of these phases in the BCR SE were observed. The amount of Tl released as the exchangeable/acid-extractable fraction (55-82% of the total Tl content) showed a substantial H(+)-promoted dissolution of all Fe(III) and Mn(III, IV) oxides (corresponding to up to 61% of solid Fe dissolved) and incongruent (increased) extraction of Tl from ferrihydrite and goethite. Reductive conditions of the second SE step were insufficient to complete goethite dissolution with corresponding Tl amount retained in the solid phase. Similarly, insufficient oxidation of sphalerite and lower Tl recovery of the oxidisable fraction was identified. In contrast, the BCR SE seems to produce well predictable results of Tl leaching from Tl-bearing calcite and feldspar. Only 70% of total Tl content was extracted from Tl-modified illite in the exchangeable/acid-extractable step, while 30% was associated with the reducible and residual fractions, i.e., Tl was strongly fixed to the illite matrix.
这项工作侧重于 BCR（社区参考局）顺序提取（SE）方案中含 Tl 相的特殊行为，即在其与石英的简单模型混合物中，含 Tl 的水铁矿、针铁矿、锰矿、方解石、伊利石、闪锌矿和长石。在 BCR SE 中，这些相的实际行为与预期行为存在一些显著差异。作为可交换/酸提取部分释放的 Tl 量（总 Tl 含量的 55-82%）表明，所有 Fe(III) 和 Mn(III,IV)氧化物（相当于 61%的固相 Fe 溶解）都经历了大量 H(+)促进的溶解，并且 Tl 从水铁矿和针铁矿中以非共沉淀（增加）的方式提取。第二 SE 步骤的还原条件不足以使针铁矿完全溶解，相应的 Tl 留在固相中。同样，发现硫化锌的氧化不足和可氧化部分的 Tl 回收率较低。相比之下，BCR SE 似乎可以很好地预测含 Tl 方解石和长石中 Tl 的浸出结果。在可交换/酸提取部分中，只有 70%的总 Tl 含量从 Tl 改性伊利石中提取，而 30%与可还原和残留部分相关，即 Tl 被强烈固定在伊利石基质上。
