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首页> 外文OA文献 >Towards Coated Nano-Gold Particles as Non-Reactive Tracers in Coated nZVI for In-Situ Remediation
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Towards Coated Nano-Gold Particles as Non-Reactive Tracers in Coated nZVI for In-Situ Remediation

机译：涂覆纳米金颗粒作为涂层nZVI中的非反应性示踪剂用于原位修复

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Background/Objectives. Chlorinated solvent (e.g. trichloroethene and tetrachloroethene) source zones in the subsurface pose a continuous threat to groundwater quality at many sites worldwide. Remediation of these contaminated sites is especially challenging in the presence of Dense Non-Aqueous Phase Liquids (DNAPLs) and the development of innovative remediation technologies is still needed. It has been proved, in laboratory scale as well as in field tests, that nanoparticles of zero-valent iron (nZVI) are efficient in degrading chlorinated solvents in aqueous solution, due to their large surface area and reducing ability. Stability of nZVI in aqueous emulsions and mobility of nZVI in the subsurface has been obtained through coatings. However, lack of knowledge of the fate of nZVI once they are released to the environment, including their transport, reactivity, mobility, and affinity towards various environmental phases, hinders the implementation of an effective environmental remediation process. Also, from a risk assessment perspective, it is of great interest to know the dispersion of such reactive nanoparticles in the environment. A possibility is the introduction of non-reactive tracer particles with the same mobility and partitioning properties as the reactive particles. In this study, the use of gold nanoparticles (nAu) mixed in tracer amounts to track the fate of nanoparticles in porous media is investigated, initially at the lab scale.Approach/Activities. Colloidal nAu have been of great interest for centuries due to their vibrant colors produced by the interaction with visible light. These unique optical – electronics properties along with their very low natural abundance, high chemical stability and relative low toxicity have made them useful in such tracing applications. In this project, 30 nm sized citrate stabilized nAu were and coated with amphiphilic block copolymers such as PVP-VA and PVA-COOH. The coated nAu were found to be stable in water and in a number of organic solvents as well. The partitioning of the nAu from an aqueous solution (5 mg/L) into two different DNAPLs (tri- and tetrachloroethene) was tested. The nAu mobility was investigated in sand packed columns and the breakthrough was monitored using spectrophotometry on the effluent. Results/Lessons Learned. The results showed nanoparticles with great mobility and a significant affinity for the DNAPL. The breakthrough curve from the mobility study showed that only minimal retardation and tailing occurred at both the front and back of the nAu plume. These results obtained by conducting model experiments (lab scale aerobic) using nAu coated with amphiphilic block copolymers like PVP-VA and PVA-COOH, hold great promise for the co-injection and DNAPL affinity of both reactive (nZVI) and tracer nanoparticles. DNAPL affinity of the coated nZVI is expected to target treatment of DNAPL source zones.
机译：背景/目标。地下的氯化溶剂（例如三氯乙烯和四氯乙烯）源区对全球许多地点的地下水质量构成持续威胁。在存在密集的非水相液体（DNAPL）的情况下，对这些污染部位的修复尤其具有挑战性，并且仍需要开发创新的修复技术。在实验室规模和现场测试中，已证明零价铁（nZVI）纳米颗粒由于表面积大且还原能力强，可有效降解水溶液中的氯化溶剂。 nZVI在水乳液中的稳定性和nZVI在地下的迁移性已通过涂层获得。但是，对nZVI释放到环境中后的命运缺乏了解，包括其运输，反应性，迁移性以及对各个环境阶段的亲和力，这阻碍了有效的环境修复过程的实施。而且，从风险评估的角度来看，非常重要的是要知道这种反应性纳米颗粒在环境中的分散。一种可能性是引入具有与反应性颗粒相同的迁移率和分配特性的非反应性示踪剂颗粒。在这项研究中，最初以实验室规模研究了使用以示踪剂量混合的金纳米颗粒（nAu）来跟踪纳米颗粒在多孔介质中的命运的方法。几个世纪以来，胶体nAu引起了人们极大的兴趣，因为它们与可见光相互作用产生了鲜艳的色彩。这些独特的光学电子特性以及极低的自然丰度，高化学稳定性和相对较低的毒性使它们在此类示踪应用中很有用。在该项目中，将30 nm大小的柠檬酸盐稳定的nAu涂上两亲嵌段共聚物，例如PVP-VA和PVA-COOH。发现涂覆的nAu在水中和许多有机溶剂中也是稳定的。测试了nAu从水溶液（5 mg / L）分配到两种不同的DNAPL（三-和四氯乙烯）中的分配。在砂填充柱中研究了nAu的迁移率，并使用分光光度法对流出物进行了监测。结果/经验教训。结果表明，纳米颗粒具有很大的迁移率，并且对DNAPL具有显着的亲和力。迁移率研究的突破曲线表明，nAu羽流的正反两面仅出现最小的阻滞和拖尾现象。通过使用涂有两亲嵌段共聚物（如PVP-VA和PVA-COOH）的nAu进行模型实验（实验室规模好氧）获得的这些结果，对于反应性（nZVI）和示踪剂纳米粒子的共注入和DNAPL亲和力具有广阔的前景。涂覆的nZVI的DNAPL亲和力有望靶向治疗DNAPL源区。

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