Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Tübingen 72074, Germany.
Hydrogeology, Center for Applied Geosciences, University of Tübingen, Tübingen 72074, Germany.
J Hazard Mater. 2020 Dec 5;400:123139. doi: 10.1016/j.jhazmat.2020.123139. Epub 2020 Jun 11.
Magnetite nanoparticles are often promoted as remediation agents for heavy metals such as chromium due to their reactivity and high surface area. However, their small size also makes them highly mobile increasing the risk that reacted pollutants will be transported to different locations rather than being safely controlled. Released to aquatic environments, aggregation leads to a loss of their nano-specific properties and contaminant-removal capacity. We immobilized magnetite onto sand to overcome these issues whilst maintaining reactivity. We compare biogenic magnetite and abiogenic magnetite coated sand against magnetite nanoparticles. Magnetite coatings mostly exhibited a Fe(II)/Fe(III) ratio close to stoichiometry (0.5). We tested the efficacy of the magnetite-coated sand to adsorb chromium, with respect to biogenic/abiogenic nanoparticles. Langmuir-type sorption of Cr(VI) onto magnetite (4.32 mM total Fe) was observed over the tested concentration range (10-1000 μM). Biogenic nanoparticles showed the highest potential for Cr(VI) removal with maximum adsorption capacity (Q) of 1250 μmol Cr/g Fe followed by abiogenic nanoparticles with 693 μmol Cr/g Fe. All magnetite coated sands exhibited similar sorption behavior with average Q ranging between 257-471 μmol Cr/g Fe. These results indicate coating magnetite onto sand may be more suitable than free nanoparticles for treating environmental pollutants such as chromium.
磁铁矿纳米颗粒通常因其反应活性和高表面积而被推广为用于重金属如铬的修复剂。然而，它们的小尺寸也使它们具有高度的移动性，增加了反应污染物被运输到不同位置而不是被安全控制的风险。释放到水生环境中，聚集导致其纳米特定性质和污染物去除能力的丧失。我们将磁铁矿固定在沙子上，以克服这些问题，同时保持反应活性。我们比较了生物成因磁铁矿和非生物成因磁铁矿涂层砂与磁铁矿纳米颗粒。磁铁矿涂层大多表现出接近化学计量比（0.5）的 Fe(II)/Fe(III)比值。我们测试了磁铁矿涂层砂对铬的吸附效果，相对于生物/非生物纳米颗粒。在测试的浓度范围内（10-1000 μM）观察到 Cr(VI)在磁铁矿（4.32 mM 总铁）上的 Langmuir 型吸附。生物成因纳米颗粒对 Cr(VI)的去除具有最大的潜力，最大吸附容量（Q）为 1250 μmol Cr/g Fe，其次是非生物成因纳米颗粒，为 693 μmol Cr/g Fe。所有磁铁矿涂层砂都表现出相似的吸附行为，平均 Q 值在 257-471 μmol Cr/g Fe 之间。这些结果表明，将磁铁矿涂覆在沙子上可能比自由纳米颗粒更适合处理环境污染物，如铬。
