CONACyT, Department of Environmental Technology, Institute of Metallurgy, UASLP, 78210, San Luis Potosí, Mexico.
Department of Environmental Technology, Institute of Metallurgy, UASLP, 78210, San Luis Potosí, Mexico.
Environ Pollut. 2020 Feb;257:113492. doi: 10.1016/j.envpol.2019.113492. Epub 2019 Nov 8.
Jarosite and birnessite secondary minerals play a pivotal role in the mobility, transport and fate of trace elements in the environment, although geochemical interactions of these compounds with extremely toxic thallium (Tl) remain poorly known. In this study, we investigated the sorption behavior of Tl(I) onto synthetic jarosite and birnessite, two minerals commonly found in soils and sediments as well as in mining-impacted areas where harsh conditions are involved. To achieve this, sorption and desorption experiments were carried out under two different acidic conditions and various Tl(I) concentrations to mimic natural scenarios. In addition, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and inductively coupled plasma (ICP) analyses were conducted to determine the performance of both minerals for Tl(I) sequestration. Our results indicate that both phases can effectively remove aqueous Tl by different sorption mechanisms. Jarosite preferentially incorporates Tl(I) into the structure to form Tl(I)-jarosite and eventually the mineral dorallcharite (TlFe(SO)(OH)) as increasing amounts of Tl are employed. Birnessite, however, favorably uptakes Tl(I) through an irreversible surface adsorption mechanism, underlining the affinity of Tl for this mineral in the entire concentration range studied (0.5-5 mmol L). Lastly, the presence of Tl(I) in conditions where aqueous molar ratio Tl/Mn is ∼0.25 inhibits the formation of birnessite since oxidation of Tl(I) to Tl(III) followed by precipitation of avicennite (TlO) take place. Thus, the present research may provide useful insights on the role of both jarosite and birnessite minerals in Tl environmental cycles.
次生黄钾铁矾和水钠锰矿在环境中痕量元素的迁移、传输和归宿中起着关键作用，尽管这些化合物与剧毒铊（Tl）的地球化学相互作用仍知之甚少。在这项研究中，我们研究了 Tl(I)在合成黄钾铁矾和水钠锰矿上的吸附行为，这两种矿物通常存在于土壤和沉积物以及采矿影响区，这些地区存在恶劣的条件。为了实现这一目标，在两种不同的酸性条件下进行了吸附和解吸实验，并在各种 Tl(I)浓度下进行了实验，以模拟自然情景。此外，还进行了 X 射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）和电感耦合等离子体（ICP）分析，以确定这两种矿物对 Tl(I)的固定性能。我们的结果表明，这两种相都可以通过不同的吸附机制有效地去除水溶液中的 Tl。黄钾铁矾优先将 Tl(I)纳入结构中，形成 Tl(I)-黄钾铁矾，最终形成矿物多水羟硅铊铁矾（TlFe(SO)(OH)），随着 Tl 用量的增加。然而，水钠锰矿则通过不可逆的表面吸附机制有利地吸收 Tl(I)，这突出了 Tl 在整个研究浓度范围内（0.5-5 mmol L）对这种矿物的亲和力。最后，在水合摩尔比 Tl/Mn 约为 0.25 的条件下存在 Tl(I)会抑制水钠锰矿的形成，因为 Tl(I)被氧化为 Tl(III)，随后沉淀出白铁矿（TlO）。因此，本研究可为黄钾铁矾和水钠锰矿在 Tl 环境循环中的作用提供有用的见解。
