Influence of electrode material and roughness on iron electrodeposits dispersion by ultrasonification

Iranzo, Audrey; Chauvet, Fabien; Tzedakis, Théodore

doi:10.1016/j.electacta.2015.10.052

Cited by 7 publications

(3 citation statements)

References 47 publications

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“…As indicated in a previous work [20] and also in [21], on an iron electrode, the reduction of Fe II (FeCl 2 , (NH 4 ) 2 Fe(SO 4 ) 2 and FeSO 4 for pH < $4) into Fe 0 is accompanied by the reduction of free protons H + . Therefore, hydrogen bubbles formation is expected during the electrodeposition experiments in the Hele-Shaw cell (as shown in S. Bodea et al [22]).…”

Section: Introductionsupporting

confidence: 54%

Synthesis of submicrometric dendritic iron particles in an Electrochemical and Vibrating Hele-Shaw cell: study of the growth of ramified branches

Iranzo

Chauvet

Tzedakis

2017

Electrochimica Acta

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The purpose of this study is to explore a new synthesis way for the production of iron nanoparticles exploiting the nanometric structure of long ramified iron branches formed by electrodeposition in a Hele-Shaw cell. After the growth, these branches are fragmented by the action of a vibrating element (piezoelectric disk) integrated into the cell. The emphasis is put on the growth of the ramified iron branches which is performed by galvanostatic electrodeposition in a stagnant electrolyte (FeCl 2) inside the Hele-Shaw cell (50 mm deep). The competition between the co-formation of H 2 bubbles (H + reduction) and the growth of ramified iron branches (Fe II reduction) is analyzed by varying both the applied current density j and the FeCl 2 concentration. Two regimes, depending mainly on j, are highlighted: below a threshold current density of 8 mA/cm 2 only H 2 bubbles are formed, while above this threshold, iron branches grow accompanied by the formation of H 2 bubbles which nucleate and grow at the top of the branches during their formation. The H 2 bubbles influence the branches growth especially at low j (<24 mA/cm 2) when the growth velocity of the branches is low compared to the growth rate of the bubbles. At higher j (>24 mA/cm 2), the branches follow a columnar growth with a constant front velocity, well predicted by the theory. Scanning Electron Microscopy (SEM) of the iron branches shows a dendritic structure constituted of nanometric crystallites, whose size depends on the local growth velocity: increasing the growth velocity from 3.6 mm/s to 40 mm/s leads to a decrease in the crystallites size, from $1 mm to $10 nm. Using the acoustic vibrations (4 kHz) of the piezoelectric disk, these fragile branches are successfully fragmented into submicrometric fragments of dendrites exhibiting high specific surfaces S/V (equivalent to the S/V of nanoparticles of 30 nm diameter). Advantages/Drawbacks compared to other synthesis ways as well as the optimization of the proposed synthesis are discussed.

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Section: Introductionsupporting

confidence: 54%

Synthesis of submicrometric dendritic iron particles in an Electrochemical and Vibrating Hele-Shaw cell: study of the growth of ramified branches

Iranzo

Chauvet

Tzedakis

2017

Electrochimica Acta

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“…The third route for nZVI production is the thermal reduction, which consists in the reduction of iron oxide precursor in hydrogen at high temperature. Direct electrochemical synthesis of nZVI with ultrasonication appears as a promising process for an economic and large-scale production (Chen et al 2004;Iranzo et al 2015). Finally, green synthesis by using food industry wastes of leaf extracts have been recently reported (Kharissova et al 2013;Machado et al 2015;Kozma et al 2016;Saif et al 2016).…”

Section: Nanoscale and Microscale Particlesmentioning

confidence: 99%

In Situ Chemical Reduction of Chlorinated Organic Compounds

Rodrigues

Betelu

Colombano

et al. 2020

Applied Environmental Science and Engineering for a Sustainable Future

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Chlorinated organic compounds (COCs) are common anthropogenic contaminants of soil and groundwater. COCs were industrially produced for different applications, such as dry cleaning, degreasing, or as pesticides. The presence of COCs in the environment is a major concern because of their toxicity and persistence.The most widely used method for their remediation is the conventional pump-and-treat system. However, this technology can hardly achieve a complete remediation because of geological characteristics and the presence of pore space pollution/adsorbed pollution, leading to a residual saturation. Hence, in addition to the improvement of pump-and-treat systems, in situ chemical processes have been largely developed. These chemical processes involve the injection of chemical reagents for the removal of residual source pollution and/or the treatment of plume contamination. Chemical degradation of COCs can be achieved by oxidative or reductive processes. If chemical oxidation has been first developed for in situ application, chemical reduction is one of the most important emerging remediation techniques for COCs treatment. Due to the electronegative character of chlorine substituents, COCs can effectively be transformed via reductive pathways. Moreover, reductive dechlorination has shown higher efficiency on highly chlorinated compounds. This chapter focuses on the presentation of the chemical reduction of the most common COCs pollutants, followed by kinetic and mechanistic approaches related to the use of iron-based particles. Developments on in situ chemical reduction technologies in order to enhance remediation rates are also exposed. Influence of environmental conditions for in situ applications is then developed. Finally, a case study is presented.

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“…The proposed method is applied here for the production of Fe nP from FeCl 2 as an electrolyte. In such a thin gap cell, the growth of Fe branches is known to be accompanied by the formation of H 2 bubbles due to the co-reduction of H + (Bodea et al 1999;Grujicic and Pesic 2005;Iranzo et al 2015). The influence of the operating parameters (applied current and concentration of FeCl 2 ) on the obtained deposit morphology (spatial arrangement of Fe branches and H 2 bubbles) and the microstructure of the branches, in the proposed microreactor design, has already been studied and optimal conditions have been determined (Iranzo et al 2017).…”

mentioning

confidence: 99%

Synthesis of in situ purified iron nanoparticles in an electrochemical and vibrating microreactor: study of ramified branch fragmentation by oscillating bubbles

Iranzo

Chauvet

2019

Microfluid Nanofluid

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Influence of electrode material and roughness on iron electrodeposits dispersion by ultrasonification

Cited by 7 publications

References 47 publications

Synthesis of submicrometric dendritic iron particles in an Electrochemical and Vibrating Hele-Shaw cell: study of the growth of ramified branches

Synthesis of submicrometric dendritic iron particles in an Electrochemical and Vibrating Hele-Shaw cell: study of the growth of ramified branches

In Situ Chemical Reduction of Chlorinated Organic Compounds

Synthesis of in situ purified iron nanoparticles in an electrochemical and vibrating microreactor: study of ramified branch fragmentation by oscillating bubbles

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