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首页> 外文期刊>Environmental Science & Technology >Effect of Particle Age (Fe~0 Content)and Solution pH On NZVI Reactivity:H_2 Evolution and TCE Dechlorination
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Effect of Particle Age (Fe~0 Content)and Solution pH On NZVI Reactivity:H_2 Evolution and TCE Dechlorination

机译：颗粒年龄（Fe〜0含量）和溶液pH值对NZVI反应性的影响：H_2析出和TCE脱氯

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摘要

Subsurface injection of nanoscale zerovalent iron (NZVI)has been used for the in situ remediation of chlorinated solvent plumes and DNAPL source zones.Due to the cost of materials and placement,the efficacy of this approach depends on the NZVI reactivity and longevity,selectivity for the target contaminant relative to nonspecific corrosion to yield H_2,and access to the Fe~0 in the particles.Both the reaction pH and the age of the particles (i.e.,Fe~0 content)could affect NZVI reactivity and longevity.Here,the rates of H_2 evolution and trichloroethene (TCE)reduction are measured overthe lifetime of the particles and at solution pH ranging from 6.5 to 8.9.Crystalline reactive nanoscale iron particles (RNIP)with different initial Fe~0 weight percent (48%,36%,34%,27%,and 9.6%)but similar specific surface area were studied.At the equilibrium pH for a Fe(OH)2/H_2O system (pH =8.9),RNIP exhibited first-order decay for Fe~0 corrosion (H_2 evolution)with respect to Fe~0 content with a Fe~0 half-life time of 90-180 days.A stable surface area-normalized TCE reduction rate constant 1.0 x 10~(-3)L centre dot hr~(-1)centre dot m~(-2)was observed after 20 days and remained constant for 160 days,while the Fe~0 content of the particles decreased by half,suggesting that TCE reduction is zero-order with respect to the Fe~0 content of the particle.Solution pH affected H_2 evolution and TCE reduction to a different extent.Decreasing pH from 8.9 to 6.5 increased the H_2 evolution rate constant 27 fold from 0.008 to 0.22 day~(-1),but the TCE dechlorination rate constant only doubled.The dissimilarities between the reaction orders of H_2 evolution and TCE dechlorination with respect to both Fe~0 content and H~+concentration suggest that different rate controlling steps are involved for the reduction reactions.
机译：纳米级零价铁（NZVI）的地下注入已用于原位修复氯化溶剂羽流和DNAPL源区。由于材料和放置成本的原因，该方法的有效性取决于NZVI反应性和寿命，选择性。目标污染物相对于非特异性腐蚀产生H_2，并接近颗粒中的Fe〜0。反应pH和颗粒的年龄（即Fe〜0含量）都可能影响NZVI反应性和寿命。在颗粒的整个生命周期内以及在溶液pH范围为6.5至8.9的条件下测量H_2的析出速率和三氯乙烯（TCE）的还原速率。具有不同初始Fe〜0重量百分比（48％，36％，分别研究了34％，27％和9.6％）的比表面积。在Fe（OH）2 / H_2O体系的平衡pH（pH = 8.9）下，RNIP对Fe〜0腐蚀表现出一阶衰减（相对于Fe〜0含量为Fe〜0 ha的H_2演化寿命为90-180天。20天后观察到稳定的表面积标准化TCE降低速率常数为1.0 x 10〜（-3）L中心点hr〜（-1）中心点m〜（-2）并保持160天不变，而颗粒的Fe〜0含量却降低了一半，这表明相对于颗粒的Fe〜0含量，TCE还原为零级。 pH值从8.9降低到6.5使H_2的析出速率常数从0.008增加到0.22天〜（-1）增加了27倍，但TCE的脱氯速率常数只增加了一倍。关于Fe〜0含量和H〜+浓度的比较表明，还原反应涉及不同的速率控制步骤。

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  • 来源
    《Environmental Science & Technology》 |2006年第19期|p.6085-6090|共6页
  • 作者

    YUEQIANG LIU; GREGORY V.LOWRY;

  • 作者单位

    Department of Civil and Environmental Engineering,Carnegie Mellon University,Pittsburgh,Pennsylvania 15213-3890;

  • 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);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境化学;
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