Davarzani Dorian, Derikvand Zeinab, Betelu Stéphanie, Colombano Stéfan, Nascimento Marcio, Ignatiadis Ioannis, Hubé Daniel
BRGM (French Géologique Survey), 3 Avenue Claude Guillemin, 45100 Orléans, France.
BRGM (French Géologique Survey), 3 Avenue Claude Guillemin, 45100 Orléans, France; University of Rennes, CNRS, Géosciences Rennes, UMR 6118 Rennes, France.
Sci Total Environ. 2024 Nov 1;949:174901. doi: 10.1016/j.scitotenv.2024.174901. Epub 2024 Jul 20.
Mercury pollution from natural and anthropogenic sources demands effective remediation. This study focuses on optimizing a chemical stabilization approach using sulfur-containing compounds to create stable mercury sulfide (HgS) and immobilize elemental mercury in polluted soils. We propose using xanthan gum biopolymer to enhance the in-situ delivery of sulfide microparticles, overcoming soil heterogeneities due to its non-Newtonian behavior. Stability tests indicated that increased biopolymer concentration enhances particle stability due to the viscous and shear-thinning behavior of the polymer solutions. Various combinations (12 solutions) of xanthan polymer, pyrite microparticles, and sulfide-containing reagents were tested in batch experiments. Pyrite microparticles slightly reduced the xanthan solution's viscosity while retaining its non-Newtonian character. All solutions effectively transformed liquid mercury droplets into cinnabar, demonstrating successful mercury stabilization. Notably, solutions containing PIAX and SIPX, xanthate organosulfur compounds, significantly reduced the dissolved concentration of elemental mercury. Column experiments demonstrated xanthan gum's superior performance for in-situ injection of pyrite microparticles and sulfide mixtures into the soil compared to conventional water injection. At a polymer concentration of 4 g/L, a stable displacement front and an 88 % recovery of the initially injected particle-suspension density were achieved. The combined effects of xanthate's floating behavior and xanthan gum's shear-thinning nature substantially enhanced the delivery of pyrite microparticles in porous media for soil mercury remediation. This combination reduced the aqueous elemental mercury concentration in artificially polluted sand by up to 97 %, particularly with the xanthate organosulfur compound, PIAX. Xanthate has a higher potential to react with elemental mercury to form cinnabar compared to sodium thiosulfate. Additionally, the pyrite microparticles, rendered hydrophobic in xanthate solutions, integrated into the mercury droplets, forming a black paste. This study introduces a promising approach for efficient elemental mercury stabilization in contaminated soils by integrating biopolymers, reactive soluble compounds, and pyrite microparticles for sustainable decontamination.
来自天然和人为来源的汞污染需要有效的修复方法。本研究着重于优化一种化学稳定化方法，即使用含硫化合物来生成稳定的硫化汞（HgS）并将土壤中的元素汞固定下来。我们建议使用黄原胶生物聚合物来增强硫化物微粒的原位输送，利用其非牛顿流体特性克服土壤的非均质性。稳定性测试表明，由于聚合物溶液的粘性和剪切变稀行为，生物聚合物浓度的增加会提高微粒的稳定性。在批量实验中测试了黄原胶聚合物、黄铁矿微粒和含硫试剂的各种组合（12种溶液）。黄铁矿微粒略微降低了黄原胶溶液的粘度，同时保留了其非牛顿特性。所有溶液都有效地将液态汞滴转化为辰砂，证明汞稳定化成功。值得注意的是，含有PIAX和SIPX（黄原酸有机硫化合物）的溶液显著降低了元素汞的溶解浓度。柱实验表明，与传统的水注入相比，黄原胶在将黄铁矿微粒和硫化物混合物原位注入土壤方面具有卓越性能。在聚合物浓度为4 g/L时，实现了稳定的驱替前沿和初始注入的颗粒悬浮密度88%的回收率。黄原酸的漂浮行为和黄原胶的剪切变稀特性的综合作用极大地增强了黄铁矿微粒在多孔介质中用于土壤汞修复的输送效果。这种组合将人工污染砂中的水溶态元素汞浓度降低了高达97%，特别是使用黄原酸有机硫化合物PIAX时。与硫代硫酸钠相比，黄原酸与元素汞反应形成辰砂的潜力更高。此外，在黄原酸溶液中具有疏水性的黄铁矿微粒融入汞滴中，形成黑色糊状物。本研究通过整合生物聚合物、活性可溶性化合物和黄铁矿微粒，引入了一种在污染土壤中高效稳定元素汞以实现可持续去污的有前景的方法。
