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Enhanced trichloroethylene dechlorination by carbon-modified zero-valent iron: Revisiting the role of carbon additives.
Journal of Hazardous Materials ( IF 12.2 ) Pub Date : 2020-03-18 , DOI: 10.1016/j.jhazmat.2020.122564
Xiaohong Guan 1 , Xueying Du 1 , Meichuan Liu 2 , Hejie Qin 1 , Junlian Qiao 1 , Yuankui Sun 1
Affiliation  

Given that there are still some debates on the influence of carbon modification on zerovalent iron (ZVI) decontamination process, the roles of carbon on trichloroethylene (TCE) reduction by ZVI were re-investigated in this work. Compared to activated carbons (AC) with high adsorption ability, carbon fibers (CF) with good electronic conductivity performed much better in enhancing ZVI performance in terms of both reactivity and selectivity. Moreover, it was interesting to observe that a low carbon loading is sufficient to effectively improve TCE reduction and this promoting effect would decline with further increasing the carbon amounts from 1.0 wt.% to 50 wt.%. Regarding to the ZVI selectivity, a relatively high carbon loading (especially for CF, it may be as high as 50 wt.%) was needed to protect ZVI from non-productive reactions with H2O/H+ effectively. However, a mixture of 10 wt.% AC and 1.0 wt.% CF could combine their respective merits of inhibiting side reactions and enhancing TCE reduction, and thus simultaneously enhanced the reactivity and selectivity of ZVI. Mechanistic investigations revealed that carbon modification could enhance the ZVI performance through improving TCE adsorption and/or accelerating electron transfer, while the latter one may play a more important role especially at high carbon loadings.

中文翻译:

碳改性的零价铁增强的三氯乙烯脱氯作用:重新探讨碳添加剂的作用。

鉴于仍存在关于碳改性对零价铁(ZVI)净化过程影响的争论,因此在这项工作中对碳在ZVI还原三氯乙烯(TCE)中的作用进行了重新研究。与具有高吸附能力的活性炭(AC)相比,具有良好电导率的碳纤维(CF)在增强ZVI性能方面的反应性和选择性都更好。此外,有趣的是观察到低的碳负载量足以有效地改善TCE的降低,并且随着碳含量从1.0重量%进一步增加至50重量%,该促进效果将下降。关于ZVI的选择性,相对较高的碳载量(特别是对于CF,它可能高达50 wt。%)才能有效保护ZVI避免与H2O / H +发生非生产性反应。然而,10重量%AC和1.0重量%CF的混合物可以结合它们各自抑制副反应和增强TCE还原的优点,并因此同时提高ZVI的反应性和选择性。机理研究表明,碳改性可通过改善TCE吸附和/或加速电子转移来增强ZVI性能,而后者可能在碳载量较高时起更重要的作用。
更新日期:2020-03-19
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