Application of pH, ORP, and DO monitoring to evaluate chromium(VI) removal from wastewater by the nanoscale zero-valent iron (nZVI) process

Yu, Ruey-Fang; Chi, Fung-Hwa; Cheng, W. T. K.; Chang, Jen-Chieh

doi:10.1016/j.cej.2014.06.002

Cited by 67 publications

(21 citation statements)

References 32 publications

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“…7 , the Cr(VI) removal efficiency of M48h-Al O is very high in comparison with the other tested particles, being significantly higher when it is normalized with SSA. M48h-Al O Cr(VI) removal efficiency is within the range of the values reported for nZVI obtained from borohydride method (Fe ) at similar pH (Li et al 2008 ;Xie and Cwiertny 2012 ;Yu et al 2014 ). This can be considered as a good result: first, because Fe is known to have a higher reactivity than other commercial nZVI products (Kim et al 2012 ) and second, due to the fact that in the present case the batches were not stirred during reaction.…”

Section: Tablesupporting

confidence: 56%

Improvements in nanoscale zero-valent iron production by milling through the addition of alumina

et al. 2016

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A new milling procedure for a cost-effective production of nanoscale zero-valent iron for environmental remediation is presented. Conventional ball milling of iron in an organic solvent as Mono Ethylene Glycol produces flattened iron particles that are unlikely to break even after very long milling times. With the aim of breaking down these iron flakes, in this new procedure, further milling is carried out by adding an amount of fine alumina powder to the previously milled solution. As the amount of added alumina increases from 9 to 54 g l-1, a progressive decrease of the presence of flakes is observed. In the latter case, the appearance of the particles formed by fragments of former flakes is rather homogeneous, with most of the final nanoparticles having an equivalent diameter well below 1 µm and with an average particle size in solution of around 400 nm. An additional increase of alumina content results in a highly viscous solution showing worse particle size distribution. Milled particles, in the case of alumina concentrations of 54 g l-1, have a fairly large specific surface area and high Fe(0) content. These new particles show a very good Cr(VI) removal efficiency compared with other commercial products available. This good reactivity is related to the absence of an oxide layer, the large amount of superficial irregularities generated by the repetitive fracture process during milling and the presence of a fine nanostructure within the iron nanoparticles.Peer ReviewedPreprin

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Section: Tablesupporting

confidence: 56%

Improvements in nanoscale zero-valent iron production by milling through the addition of alumina

et al. 2016

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“…The highest reaction rate corresponds to the 25P nanoparticles, with negligible differences between the un-activated and activated particles (i.e., higher for the A 25P particles with a removal capacity of 25.8 mg Cr(VI)/g Fe(0)). Even higher reaction rates have been reported in the literature for experiments in which the batches were stirred [42], the solutions were buffered to a lower pH [22,28] or the nZVI were obtained by the borohydride reduction method [43].…”

Section: Reduction Of Cr(vi)mentioning

confidence: 94%

Activation process of air stable nanoscale zero-valent iron particles

Ribas

Černík

Benito

et al. 2017

Chemical Engineering Journal

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Nanoscale Zero Valent Iron (nZVI) represents a promising material for subsurface water remediation technology. However, dry, bare nZVI particles are highly reactive, being pyrophoric when they are in contact with air. The current trends of nZVI manufacturing lead to the surface passivation of dry nZVI particles with a thin oxide layer, which entails a decrease in their reactivity. In this work an activation procedure to recover the reactivity of air-stable nZVI particles is presented. The method consists of exposing nZVI to water for 36 hours just before the reaction with the pollutants. To assess the increase in nZVI reactivity based on the activation procedure, three types of nZVI particles with different oxide shell thicknesses have been tested for Cr(VI) removal. The two types of air-stable nZVI particles with an oxide shell thickness of around 3.4 and 6.5 nm increased their reactivity by a factor of 4.7 and 3.4 after activation, respectively. However, the pyrophoric nZVI particles displayed no significant improvement in reactivity. The improvement in reactivity is related mainly to the degradation of the oxide shell, which enhances electron transfer and leads secondarily to an increase in the specific surface area of the nZVI after the activation process. In order to validate the activation process, additional tests with selected chlorinated compounds demonstrated an increase in the degradation rate by activated nZVI particles.

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“…In Yu's case, it was found that higher pH values resulted in higher Cr(VI) removal efficiencies, which was because more OH -ions were generated when more Cr(VI) was reduced to Cr(III) by the nano zero-valent (nZVI) iron particle [21] . As the efficiency of zero-valent iron nanoparticles (ZVINs) for the Cr(VI) removal was strongly decrease due to particle agglomeration, Esfahani et.…”

Section: Application Of Nanotechnologymentioning

confidence: 99%

“…One the other hand, various kinds of nanomaterial also enhance the Cr(VI) reduction activity like TiO2 nanoparticles for photocatalytic reduction [10,11] . This article mainly showed newly technique for Cr(VI) removal including membrane separation [6,12,13] , photocatalytic reduction [14,15,16] , adsorption [17,18,19] , and application of nanotechnology [20,21] .…”

Section: Introductionmentioning

confidence: 99%

Physio-chemical treatment technologies for chromium removal

Zhang¹,

Li²

2017

Proceedings of the 2016 4th International Conference on Renewable Energy and Environmental Technology (ICREET 2016)

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Abstract. The article reviews the technical applicability of various physio-chemical treatments for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. A particular focus is given to membrane electrolysis, photocatalytic reduction, adsorption and the application of nanotechnology in Cr(VI) removal. About 50 published studies (2011)(2012)(2013)(2014)(2015)(2016)(2017) are reviewed. Liquid membrane and electrodialysis were combined. Metal-organic frameworks (MOFs) emerged to enhance photocatalytic reduction. It is evident that adsorption is the most frequently studied and widely applied for the treatment of Cr(VI). And nanotechnology is mainly applied to nanoadsorbent which exhibited both reduction and adsorption capabilities. In general, further researches on methods with cost-effectiveness, technical-applicability, and plant-simplicity are vital for heavy metal removal such as chromium.

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Application of pH, ORP, and DO monitoring to evaluate chromium(VI) removal from wastewater by the nanoscale zero-valent iron (nZVI) process

Cited by 67 publications

References 32 publications

Improvements in nanoscale zero-valent iron production by milling through the addition of alumina

Improvements in nanoscale zero-valent iron production by milling through the addition of alumina

Activation process of air stable nanoscale zero-valent iron particles

Physio-chemical treatment technologies for chromium removal

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