Selenate reduction by sulfidized zero-valent iron (S-ZVI)

一方面，硒是一种必需的营养素，另一方面，浓度过高时，它是剧毒的。在水中最易溶的是亚硒酸盐（Se(IV)）和硒酸盐（Se(VI)）。由于它们的溶解度，这两个物种在水生食物链中都能迅速达到有毒水平。在这个提议中，我们将探索硫化改性零价铁（S-ZVI）将Se（VI）还原为Se(0)和/或Se（-II）的潜力。ZVI的硫化作为一种利用ZVI作为非生物还原剂来提高污染物降解的选择性和特异性的方法，在过去的3到4年里受到了越来越多的关注。到目前为止，还没有研究对硒酸盐去除的影响。在拟议的研究中，我们将沿着三个工作包研究以下假设：i) S- zvi的S/Fe比决定其对Se（VI）的反应性，ii)氧和Fe（ii）的存在影响S- zvi还原Se（VI）的有效性，iii)由于静电效应，S- zvi对Se（VI）的还原受pH的影响，iv)在过滤床系统中应用S- zvi颗粒是去除溶液中硒酸盐的有效方法。S-ZVI和硒酸盐之间相互作用的动力学和机制将在与加拿大光源合作的批量实验中结合基于同步加速器的方法进行研究。此外，我们将进行S-ZVI填充的过滤床实验。

One the one hand, selenium is an essential nutrient, on the other hand it is highly toxic at elevated concentrations. The most soluble species in water are selenite (Se(IV)) and selenate (Se(VI)). Because of their solubility, both species can rapidly attain toxic levels in the aquatic food chain. In this proposal we will explore the potential of sulfide modified zero-valent iron (S-ZVI) to reduce Se(VI) to Se(0) and/or Se(-II). Sulfidation of ZVI has received growing attention in the last 3 to 4 years as a method to enhance selectivity and specificity of contaminant degradation by using ZVI as an abiotic reductant. To date, no study has been performed the effect on selenate removal. In the proposed research we will study along three work packages the following hypothesis: i) The S/Fe ratio of S-ZVI determines its reactivity towards Se(VI), ii) the presence of oxygen and Fe(II) affects the effectiveness of S-ZVI to reduce Se(VI), iii) Se(VI) reduction by S-ZVI is affected by pH due to electrostatic effects, and iv) application of S-ZVI particles in filter-bed systems is an effective method for removal of selenate from solution. The kinetics and mechanisms of the interaction between S-ZVI and selenate will be studied in batch experiments in combination with synchrotron based methods in collaboration with the Canadian Light Source. In addition we will perform filter-bed experiments packed with S-ZVI.