Antimony (Sb) is a hazardous metalloid that is ubiquitous in the environment. Its toxicity and mobility are strongly influenced by the valence state. Particles and aquatic colloids are abundant in natural water; however, there is little understanding of how Sb(III) is oxidized by these substances. In this study, cross-flow ultrafiltration is used to separate the substances in natural water samples into macroparticles (>1 μm), microparticles (1–0.1 μm), colloids (<0.1 μm, >1 kDa), and dissolved substances (<1 kDa). The effects of these different components on oxidation of Sb(III) were comprehensively investigated by kinetic measurements with the aid of quenchers under simulated sunlight irradiation and dark conditions. The results show that 95% of the Sb(III) oxidation process was done by the particles (macroparticles and microparticles) and aquatic colloids (colloids and dissolved substances). Macroparticles oxidized Sb(III) via active substances such as natural organic matter (NOM) and iron oxides, while colloids impacted the oxidation process via dissolved organic matter (DOM) with active groups such as amino acid-like organic matter. The dissolved substances oxidized Sb(III) via iron ions and some micromolecule organic matter. Common free ions in natural water had no effect on the oxidation of Sb(III). The reactive oxygen species (ROS) and excited triplet states of DOM (³DOM*) produced by oxidants under photoirradiation can accelerate the oxidation of Sb(III). These results indicate that Sb(III) can be oxidized to Sb(V) rapidly with the help of sunlight in the presence of particles and colloids, and this oxidation process will greatly influence the fate of Sb(III) in natural water.

中文翻译：

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颗粒和水胶体对天然水中Sb（III）氧化的影响

锑（Sb）是一种有害的准金属，在环境中无处不在。价态强烈影响其毒性和迁移率。天然水中的颗粒和水胶体丰富；但是，对于这些物质如何氧化Sb（III）知之甚少。在这项研究中，使用错流超滤将天然水样品中的物质分离为大颗粒（> 1μm），微粒（1-0.1μm），胶体（<0.1μm，> 1 kDa）和溶解物（< 1 kDa）。在模拟阳光照射和黑暗条件下，借助淬灭剂进行动力学测量，全面研究了这些不同组分对Sb（III）氧化的影响。结果表明，Sb（III）氧化过程的95％是由颗粒（大颗粒和微粒）和水生胶体（胶体和溶解的物质）完成的。大颗粒通过诸如天然有机物（NOM）和氧化铁之类的活性物质氧化Sb（III），而胶体则通过具有诸如氨基酸类有机物之类的活性基团的溶解有机物（DOM）来影响氧化过程。溶解的物质通过铁离子和一些小分子有机物氧化了Sb（III）。天然水中常见的游离离子对Sb（III）的氧化没有影响。DOM的活性氧（ROS）和激发三重态 而胶体则通过具有活性基团（如氨基酸样有机物）的溶解有机物（DOM）影响了氧化过程。溶解的物质通过铁离子和一些小分子有机物氧化了Sb（III）。天然水中常见的游离离子对Sb（III）的氧化没有影响。DOM的活性氧（ROS）和激发三重态 而胶体则通过具有活性基团（如氨基酸样有机物）的溶解有机物（DOM）影响了氧化过程。溶解的物质通过铁离子和一些小分子有机物氧化了Sb（III）。天然水中常见的游离离子对Sb（III）的氧化没有影响。DOM的活性氧（ROS）和激发三重态在光照射下氧化剂产生的³ DOM *）可以加速Sb（III）的氧化。这些结果表明，在有颗粒和胶体存在的情况下，借助阳光可以将Sb（III）迅速氧化为Sb（V），这种氧化过程将极大地影响天然水中Sb（III）的命运。