Zero-valent iron nanomaterial Fe0@Fe2MnO4 for ultrasensitive electroanalysis of As(III): Fe0 influenced surficial redox potential

2021 ◽  
Author(s):  
Meng Yang ◽  
Feng Xie ◽  
Shan-Shan Li ◽  
Chu-Hong Lin ◽  
Xing-Jiu Huang ◽  
...  
Keyword(s):  
Redox Potential ◽  
Electrochemical Detection ◽  
Zero Valent Iron ◽  
Enhanced Sensitivity

A novel zero-valent iron nanomaterial (Fe0@Fe2MnO4) was synthesized and achieved an ultrasensitive electrochemical detection of As(III). It was found that the enhanced sensitivity is attributed to the surficial catalytic redox...

Enhanced Sensitivity for Electrochemical Detection Using Screen-Printed Diamond Electrodes via the Random Microelectrode Array Effect

2016 ◽  
Vol 88 (3) ◽  
pp. 1753-1759 ◽  
Author(s):  
Takeshi Kondo ◽  
Ikuto Udagawa ◽  
Tatsuo Aikawa ◽  
Hironori Sakamoto ◽  
Isao Shitanda ◽  
...  
Keyword(s):  
Electrochemical Detection ◽  
Microelectrode Array ◽  
Diamond Electrodes ◽  
Enhanced Sensitivity ◽  
Screen Printed

scholarly journals Synthesis of Aqueous Suspensions of Zero-Valent Iron Nanoparticles (nZVI) from Plant Extracts: Experimental Study and Numerical Modeling

2019 ◽  
Vol 3 (6) ◽  
pp. 344-360 ◽  
Author(s):  
Michalis Karavasilis ◽  
Christos D. Tsakiroglou
Keyword(s):  
Redox Potential ◽  
Gallic Acid ◽  
Plant Extracts ◽  
Iron Nanoparticles ◽  
Hydrogen Atom Transfer ◽  
Zero Valent Iron ◽  
Iron Sulfate ◽  
Sulfate Heptahydrate ◽  
Numerical Predictions ◽  
Zero Valent Iron Nanoparticles

Plant extracts were produced from Camellia sinesis (Green Tea) and Punica granatum (pomegranate), and the total concentration of polyphenols was measured in terms of equivalent concentration of Gallic acid by using the Folin-Ciocalteu method. Zero Valent Iron nanoparticles (nZVIs) were synthesized in a semi-batch reactor by mixing a pre-specified volume of plant extract or Gallic Acid solution with an aqueous solution of iron sulfate heptahydrate (FeSO4·7H2O). To monitor the kinetics of nZVI synthesis, the transient responses of solution pH and redox potential (Eh) were recorded with two probes adequately connected with a data acquisition card. The nanoparticles were characterized by a variety of techniques: Dynamic Light Scattering (DLS), ζ-potential, Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, Transmission Electron Microscopy (TEM). A kinetic parametric model, based on two parallel single electron transfer (SET) and hydrogen atom transfer (HAT) reactions, was suggested to quantify the dynamics of ferrous ions reduction to zero valence, and its parameters were estimated for each experimental system by matching the transient response of pH. The temporal changes of redox potential during nZVI synthesis were indicative of the reaction progress and agreed with the numerical predictions in semi-quantitative basis.  The numerical model enabled us to track the temporal variation of the concentration of iron and polyphenol species, and calculate the yield of ZVI synthesis. The reactivity of nZVIs was assessed by measuring their capacity to reduce hexavalent chromium Cr (VI) in aqueous solutions prepared from potassium dichromate (K2Cr2O7).

Electrochemical Enhancement on Utilizing Zero-Valent Iron to Degrade Trichloroethylene

2014 ◽  
Vol 955-959 ◽  
pp. 366-370
Author(s):  
Jian Long Chen ◽  
Yi Sung Liu ◽  
Chih Chao Wu ◽  
Jenn Chun Chu ◽  
Chih Feng Chung ◽  
...  
Keyword(s):  
Redox Potential ◽  
Processing Time ◽  
Degradation Rate ◽  
Degradation Products ◽  
Chloride Concentration ◽  
Zero Valent Iron ◽  
Electrochemical Technique ◽  
Batch Adsorption ◽  
Applied Current ◽  
Tce Degradation

The objective of this research is to enhance the degrading ability of zero-valent iron (ZVI) on trichloroethylene (TCE) by using electrochemical technique. ZVI has been shown to effectively degrade TCE by reductive dechlorination, a process in which the ZVI, acting as a reducing agent, causes the chlorine to separate from TCE sequentially. The efficiency of this technique could be enhanced by lowering the redox potential of ZVI using electrochemical methods. In this research the lowering of redox potential was achieved by filling granular ZVI into a cathode compartment in a reactor. The ZVI was mixed with granular graphite to increase the overall electrical conductivity before being filled into the cathode. The anode and cathode compartments were separated with a Nafion membrane. The loss of TCE due to adsorption by the granular graphite during the experiments was evaluated by conducting batch adsorption tests. The electrochemical experiments were conducted by applying a direct current using a potentiostat. The TCE concentration as well as possible degradation products was analyzed with gas chromatography equipped with a mass detector. Chloride concentration was measured with ion chromatography. The results of adsorption tests of TCE by granular graphite fits a linear isotherm with a Kdvalue of 2.3 L/kg, which is comparable to values reported in the literature. Results from the TCE degradation experiments leads to two major conclusions: (1) degradation of TCE was facilitated by the applied current even when the cathode was filled with only granular graphite and (2) degradation rate of TCE by ZVI was increased by the applied current. The degradation rate of TCE could be fitted with a pseudo-first-order kinetics; the reaction rate constant, kh, increases from 0.017 at no current to 0.064 h-1at a current of 100 mA. No degradation product was observed in the liquid phase. In the gaseous phase, however, cis-1,2-dichloroethylene was observed. The applied current also caused the increasing rate of pH to decrease. The pH of the solution after 8h of processing time increased from 5.7 to 8.6 at no current, whereas it increased from 5.7 to 5.9 with the same processing time. This suggests the applied current caused the decrease of the corrosion rate of ZVI. The results of this study show the electrochemical technique not only increased the TCE degradation rate by ZVI but also decreased the consumption of ZVI by corrosion. Thus, the technique can be applied to prolong the life of ZVI installed in the field for TCE degradation.

An electrochemical detection of cadmium (II) and lead (II) ions using a polymer-modified electrode with a Schiff base by square wave voltammetry

2021 ◽  
Author(s):  
Mohammed Qasim Mohammed ◽  
Hani Khalil Ismail ◽  
Hasan Fisal Alesary ◽  
Stephen Barton
Keyword(s):  
Schiff Base ◽  
Modified Electrode ◽  
Electrochemical Detection ◽  
Square Wave Voltammetry ◽  
Electrochemical Behaviour ◽  
Modified Electrodes ◽  
Polymer Coatings ◽  
Square Wave ◽  
Enhanced Sensitivity ◽  
Wave Voltammetry

Abstract The work herein concentrates on the electrochemical detection of heavy metal ions, specifically cadmium and lead ions. The introduction and modification of functional groups such as Schiff bases had led to an enhanced sensitivity of the electrode to analytes. In this study, a platinum electrode has for the first time been modified with poly(3,4- ethylenedioxythiophene) (PEDOT/Schiff base) in CH2Cl2 containing Bu4NPF6 for use to detection cadmium (II) and lead (II) ions. The structure and morphology of the polymer coatings were characterised by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), respectively. The electrochemical synthesis and redox state response in monomer-free synthesised films have been studied by cyclic voltammetry. Moreover, the effect of scan rate on the electrochemical behaviour of the modified electrodes was also studied. The voltammetric findings have been used to calculate the surface coverage required for the polymer films and the stability of polymer electrodes in the monomer-free solutions. Square wave voltammetry (SWV) was applied for the determination of cadmium (II) and lead (II) ion concentrations and to assess the effects of pH on aqueous samples. The limits of detection for the modified electrode for cadmium (II) and lead (II) were found to be 0.95 μg L-1 and 1.84 μg L-1, respectively. These findings revealed that modified films can be considered good candidates for application in electrochemical detection devices

E-pH Diagram of Fe-N-H2O System and its Application in Nitrate Removal from Water by SSI

2012 ◽  
Vol 251 ◽  
pp. 411-415
Author(s):  
Jun Guo Li ◽  
Yan Shi ◽  
Fan Wang
Keyword(s):  
Redox Potential ◽  
High Activity ◽  
Intermediate Product ◽  
Water Solution ◽  
Nitrate Removal ◽  
Zero Valent Iron ◽  
Nitrite Reduction ◽  
Reduction Product ◽  
Static State ◽  
Nitrate And Nitrite

Spherical sponge iron (SSI) with high activity and intension could be utilized to remove nitrate from wastewater. Reduction product of nitrate by SSI was investigated through static state experiment combined with E-pH diagram of Fe-N-H2O system. In a certain range of pH and redox potential, the speciation of iron include Fe0, Fe2+, Fe3+, Fe(OH)2 and Fe(OH)3, and the speciation of N was NO3-, N2, NH4+, or NH3 as the initial speciation of N was nitrate. pH in solution increased to above 10 in 6min because of quick erosion battery reaction of zero-valent iron in solution. Moreover, the E value in solution declined quickly to the minimum and then increased slightly because of dissolution of oxygen from atmosphere. It was suggested that nitrite was the intermediate product during reduction of nitrate by SSI, and ammonium was the finial product of nitrate and nitrite reduction. Nitrate removal from wastewater was related with escape of ammonia, which was gas state of ammonium in water, when the water solution was alkaline.

E-pH Diagram of Fe-N-H2O System and its Application in Nitrite

2012 ◽  
Vol 562-564 ◽  
pp. 152-155
Author(s):  
Jun Guo Li ◽  
Yan Shi ◽  
Fan Wang ◽  
Yan Ping Feng
Keyword(s):  
Redox Potential ◽  
Water Solution ◽  
Sponge Iron ◽  
Zero Valent Iron ◽  
Reduction Product ◽  
Static State ◽  
Nitrite Removal

Reduction product of nitrite by Spherical sponge iron (SSI) was investigated through static state experiment combined with E-pH diagram of Fe-N-H2O system. In a certain range of pH and redox potential, the speciation of iron include Fe0, Fe2+, Fe3+, Fe(OH)2 and Fe(OH)3, and the speciation of N was NO2, NO3-, N2, NH4+ or NH3 as the initial speciation of N was nitrite. pH in solution increased to above 10 in 6min because of rapid erosion battery reaction of zero-valent iron. Moreover, the E value in solution declined quickly to the minimum and then increased slightly because of dissolution of oxygen from atmosphere. It was suggested that ammonium was the finial product during the reduction of nitrite by SSI. Nitrite removal from wastewater was related with escape of ammonia, which was gas state of ammonium, when the water solution was alkaline.

β-Cyclodextrin-Platinum Nanoparticles/Graphene Nanohybrids: Enhanced Sensitivity for Electrochemical Detection of Naphthol Isomers

2012 ◽  
Vol 7 (4) ◽  
pp. 732-737 ◽  
Author(s):  
Gangbing Zhu ◽  
Pengbo Gai ◽  
Liang Wu ◽  
Jianhui Zhang ◽  
Xiaohua Zhang ◽  
...  
Keyword(s):  
Electrochemical Detection ◽  
Platinum Nanoparticles ◽  
Enhanced Sensitivity
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