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首页> 外文学位 >Preparation, characterization, and applications of polysaccharide-stabilized metal nanoparticles for remediation of chlorinated solvents in soils and groundwater.
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Preparation, characterization, and applications of polysaccharide-stabilized metal nanoparticles for remediation of chlorinated solvents in soils and groundwater.

机译：多糖稳定的金属纳米颗粒的制备，表征和应用，用于修复土壤和地下水中的氯化溶剂。

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摘要

Removal of chlorinated solvents in groundwater and soils represents one of the most challenging environmental issues. Highly reactive palladized iron (Fe-Pd) nanoparticles offer the potential to migrate in the soil and rapidly degrade the contaminants in source zones and became an attractive alternative for chlorinated solvent remediation. However, due to their high surface energy, Fe-Pd nanoparticles prepared using current methods tend to agglomerate immediately to form large agglomerates, rendering them undeliverable to the targeted area. This study reports that select food-grade starch and carboxymethyl cellulose (CMC) can be used as green stabilizers to produce highly dispersible Fe-Pd nanoparticles, which are reactive and mobile in soil and suitable for in situ injection.;Transmission electron microscopy (TEM) showed that the average particle sizes of both starch- and CMC-stabilized iron nanoparticles were less than 20 nm. Fourier transform infrared (FTIR) spectroscopy results suggested that stabilizer molecules were adsorbed to iron nanoparticles resulting in a steric layer, and thereby, preventing the nanoparticles from agglomeration. The stabilized iron nanoparticles were mobile in the porous media. For example, the CMC-stabilized iron nanoparticles had a low sticking efficiency of 0.0025 in the sand. Meanwhile, the stabilized nanoparticles displayed remarkably greater reactivity than non-stabilized particles. Batch tests demonstrated that the CMC-stabilized nanoparticles degraded trichloroethene (TCE) 17 times faster than non-stabilized counterparts. Further studies showed that CMC may inhibit TCE degradation at a stabilizer-to-Fe molar ratio greater than 0.0124. Within the same homologous series, CMC of greater molecular weight resulted in more reactive nanoparticles. Through selecting the type of stabilizers and synthesizing conditions, the size of the stabilized ZVI nanoparticles were also controlled.;Two field tests carried out in California and Alabama confirmed the unprecedented soil mobility and dechlorination reactivity of the CMC-stabilized Fe-Pd nanoparticles. Groundwater samples from the Alabama site also showed significant promotion of enhanced biodegradation of chlorinated solvent contaminants up to 4 months after injection.;The feasibility of using CMC for synthesis of highly reactive Pd nanoparticles was also investigated in this study. The resultant CMC-Pd nanoparticles exhibited rather high catalytic activity for hydrodechlorinatino of TCE (k obs > 828 L · gPd -1 min-1) and hold the promise for future applications in chlorinated solvent remediation.
机译：去除地下水和土壤中的氯化溶剂是最具挑战性的环境问题之一。高反应性的钯铁（Fe-Pd）纳米颗粒具有在土壤中迁移并迅速降解源区中污染物的潜力，并成为氯化溶剂修复的有吸引力的替代方法。然而，由于它们的高表面能，使用当前方法制备的Fe-Pd纳米颗粒趋于立即附聚以形成大的附聚物，使得它们不可递送至目标区域。这项研究报告指出，选择食品级淀粉和羧甲基纤维素（CMC）可以用作绿色稳定剂，以生产高度分散的Fe-Pd纳米颗粒，这些纳米颗粒在土壤中具有反应性和移动性，适合原位注射。 ）显示淀粉和CMC稳定的铁纳米颗粒的平均粒径均小于20 nm。傅立叶变换红外（FTIR）光谱结果表明，稳定剂分子被吸附到铁纳米颗粒上，形成空间层，从而防止了纳米颗粒的团聚。稳定的铁纳米颗粒可在多孔介质中移动。例如，CMC稳定的铁纳米颗粒在沙子中的粘附效率低至0.0025。同时，稳定的纳米颗粒显示出比未稳定的颗粒显着更高的反应性。批量测试表明，CMC稳定的纳米颗粒降解三氯乙烯（TCE）的速度比非稳定的对应物快17倍。进一步的研究表明，CMC可以在稳定剂与铁的摩尔比大于0.0124时抑制TCE降解。在相同的同源序列中，分子量更大的CMC导致更多的反应性纳米粒子。通过选择稳定剂的类型和合成条件，还可以控制稳定的ZVI纳米粒子的大小。在加利福尼亚和阿拉巴马州进行的两次现场测试证实，CMC稳定的Fe-Pd纳米粒子具有前所未有的土壤迁移率和脱氯反应性。阿拉巴马州站点的地下水样品在注入后长达4个月的时间里也显示出对促进氯化溶剂污染物生物降解的显着促进作用。所得的CMC-Pd纳米颗粒对TCE的加氢脱氯表现出相当高的催化活性（k obs> 828 L·gPd -1 min-1），并有望在今后的氯化溶剂修复中得到应用。

著录项

  • 作者

    He, Feng.;

  • 作者单位

    Auburn University.;

  • 授予单位 Auburn University.;
  • 学科 Environmental engineering.;Civil engineering.;Chemical engineering.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 277 p.
  • 总页数 277
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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