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首页> 外文期刊>Environmental Science & Technology >Adsorbed Polyelectrolyte Coatings Decrease Fe~0 Nanoparticle Reactivity With Tce In Water: Conceptual Model And Mechanisms
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Adsorbed Polyelectrolyte Coatings Decrease Fe~0 Nanoparticle Reactivity With Tce In Water: Conceptual Model And Mechanisms

机译：吸附的聚电解质涂层降低水中Fe〜0纳米粒子与Tce的反应性：概念模型和机理

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摘要

The surfaces of reactive nanoscale zerovalent iron (NZVI) particles used for in situ groundwater remediation are modified with polymers or polyelectrolytes to enhance colloidal stability and mobility in the subsurface. However, surface modification decreases NZVI reactivity. Here, the TCE dechlorination rate and reaction products are measured as a function of adsorbed polyelectrolyte massforthree commercially available polyelectrolytes used for NZVI surface modification including polyfstyrene sulfonate) (PSS), carboxymethyl cellulose (CMC), and polyaspartate (PAP). The adsorbed mass, extended layer thickness, and TCE-polyelectrolyte partition coefficient are measured and used to explain the effect of adsorbed polyelectrolyte on NZVI reactivity. For all modifiers, the dechlorination rate constant decreased nonlinearly with increasing surface excess, with a maximum of a 24-fold decrease in reactivity. The TCE dechlorination pathways were not affected. Consistent with Scheutjens-Fleer theory for homopolymer adsorption, the nonlinear relationship between the dechlorination rate and the surface excess of adsorbed polyelectrolyte suggests that adsorbed polyelectrolyte decreases reactivity primarily by blocking reactive surface sites at low surface excess where they adsorb relatively flat onto the NZVI surface, and by a combination of site blocking and decreasing the aqueous TCE concentration at the NZVI surface due to partitioning of TCE to adsorbed polyelectrolytes. This explanation is also consistent with the effect of adsorbed polyelectrolyte on acetylene formation. This conceptual model should apply to other medium and high molecular weight polymeric surface modifiers on nanoparticles, and potentially to adsorbed natural organic matter.
机译：用于原位地下水修复的活性纳米级零价铁（NZVI）颗粒的表面用聚合物或聚电解质改性，以增强胶体稳定性和在地下的流动性。但是，表面改性会降低NZVI反应性。在此，TCE的脱氯速率和反应产物是作为吸附的聚电解质质量的函数进行测量的，用于NZVI表面改性的三种市售聚电解质包括聚苯乙烯磺酸盐（PSS），羧甲基纤维素（CMC）和聚天冬氨酸盐（PAP）。测量吸附质量，扩展层厚度和TCE-聚电解质分配系数，并用来解释吸附的聚电解质对NZVI反应性的影响。对于所有改性剂，脱氯速率常数随表面过量的增加而非线性降低，反应活性最大降低24倍。 TCE脱氯途径未受影响。与均聚物吸附的Scheutjens-Fleer理论相一致，脱氯速率与吸附的聚电解质的表面过量之间的非线性关系表明，吸附的聚电解质主要是通过在低表面过量处阻止反应性表面位点来降低反应性，因为它们在NZVI表面相对平坦地吸附，由于TCE分配到吸附的聚电解质上，结合位点阻断和降低NZVI表面的TCE水溶液浓度。该解释也与吸附的聚电解质对乙炔形成的作用一致。该概念模型应适用于纳米颗粒上的其他中高分子量聚合物表面改性剂，并可能适用于吸附的天然有机物。

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  • 来源
    《Environmental Science & Technology》 |2009年第5期|1507-1514|共8页
  • 作者

    TANAPON PHENRAT; YUEQIANG LIU; ROBERT D. TILTON; GREGORY V. LOWRY;

  • 作者单位

    Center for Environmental Implications of NanoTechnology (CEINT) and Departments of Civil & Environmental Engineering;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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