A New Ultrasound-Assisted Method of Wastewater Treatment By Air-Stable Nanosized Zero-Valent Iron

Mikhailov, I. Yu.; Mandal, Arup; Kotov, S. G.; Кузнецов, Денис

doi:10.1166/adel.2013.1025

Cited by 5 publications

(3 citation statements)

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“…Ultrasound has commonly been used to improve the dispersivity and stability of NZVI during decontamination of wastewater. , This process induces cavitation leading to extremely high local temperatures (up to 10 000 K) and pressures (up to 5000 bar) . This can cause pitting and cracking at particle surfaces resulting in the removal of the passivated surface (oxyhydr)oxide layer .…”

Section: Depassivation Strategiesmentioning

confidence: 99%

“…134,135 This process induces cavitation leading to extremely high local temperatures (up to 10 000 K) and pressures (up to 5000 bar). 136 This can cause pitting and cracking at particle surfaces resulting in the removal of the passivated surface (oxyhydr)oxide layer. 137 The enhanced removal of several elements, including Zn 2+ , Pb 2+ and Cu 2+ , has been observed following the application of ultrasound with the increased removal due probably to the removal of the passivated layer.…”

Section: Depassivation Strategiesmentioning

confidence: 99%

“…137 The enhanced removal of several elements, including Zn 2+ , Pb 2+ and Cu 2+ , has been observed following the application of ultrasound with the increased removal due probably to the removal of the passivated layer. 136 There have been very few studies on the regeneration of passivated NZVI after decontamination 138 although several studies have been conducted on ZVI. 85,116,139 Because of the different Fe (oxyhydr)oxides that may form on corrosion of NZVI and ZVI and the inherent physical and chemical differences of these particles, it is not appropriate to necessarily assume similar mechanistic processes are operative for ZVI and NZVI.…”

Section: Depassivation Strategiesmentioning

confidence: 99%

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Advances in Surface Passivation of Nanoscale Zerovalent Iron: A Critical Review

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236

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Nanoscale zerovalent iron (NZVI) is one of the most extensively studied nanomaterials in the fields of wastewater treatment and remediation of soil and groundwater. However, rapid oxidative transformations of NZVI can result in reduced NZVI reactivity. Indeed, the surface passivation of NZVI is considered one of the most challenging aspects in successfully applying NZVI to contaminant degradation. The oxidation of NZVI can lead to the formation of Fe II-bearing phases (e.g., Fe II O, Fe II (OH) 2 , Fe II Fe III 2 O 4) on the NZVI surface or complete oxidation to ferric (oxyhydr)oxides (e.g., Fe III OOH). This corrosion phenomenon is dependent upon various factors including the composition of NZVI itself, the type and concentration of aqueous species, reaction time and oxic/anoxic environments. As such, the coexistence of different Fe oxidation states on NZVI surfaces may also, in some instances, provide a unique reactive microenvironment to promote the adsorption of contaminants and their subsequent transformation via redox reactions. Thus, an understanding of passivation chemistry, and its related mechanisms, is essential not only for effective NZVI application but also for accurately assessing the positive and negative effects of NZVI surface passivation. The aim of this review is to discuss the nature of the passivation processes that occur and the passivation byproducts that form in various environments. In particular, the review presents: i) the strengths and limitations of state-of-the-art techniques (e.g., electron microscopies and X-ray based spectroscopies) to identify passivation byproducts; ii) the passivation mechanisms proposed to occur in anoxic and oxic environments; and iii) the effects arising from synthesis procedures and the presence of inorganics/organics on the nature of the passivation byproducts that form. In addition, several depassivation strategies that may assist in increasing and/or maintaining the reactivity of NZVI are considered, thereby enhancing the effectiveness of NZVI in contaminant degradation.

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