► We produced multi-walled carbon nanotubes powder by pyrolysis of camphor mixed with ferrocene, and then used non-oxidative and oxidative acidic treatments for iron removal. ► We analyzed the ...elimination and/or oxidation of iron nanoparticles by X-ray photoelectron spectroscopy, monitoring Fe2p, O1s and C1s peaks. ► We carried out complementary investigation by thermogravimetric analysis, atomic absorption spectroscopy, Raman Spectroscopy and transmission electron microscopy (TEM) to evaluate the effectiveness of each treatment. ► A purity degree higher than 98% was achieved only with non-oxidative treatments using sonification process.
A detailed analysis by X-ray photoelectron spectroscopy was carried out on multi-walled carbon nanotube (MWCNT) surfaces after non-oxidative and oxidative purification treatments in liquid-phase. The MWCNT were produced by pyrolysis of camphor and ferrocene, that provides a high yield but with high iron contamination (∼15%wt). The elimination and/or oxidation of iron nanoparticles were monitored by Fe2p and O1s core level. Oxygen-based functional groups attachment was also investigated by C1s fitting. The effectiveness of each treatment in iron removal was evaluated by thermogravimetric analysis (TGA) and atomic absorption spectroscopy (AAS). The integrity of the MWCNT structure was verified by Raman spectroscopy (RS) and transmission electron microscopy (TEM). A purity degree higher than 98% was achieved only with non-oxidative treatments using sonification process.
► Electrochemical advanced oxidation process was studied using BDD based anodes with different boron concentrations. ► The difference between the non-active and active anodes for organics ...degradation. ► The influence of morphologic and structural properties of BDD electrodes on the RO-16 dye degradation.
Boron-doped diamond (BDD) films grown on the titanium substrate were used to study the electrochemical degradation of Reactive Orange (RO) 16 Dye. The films were produced by hot filament chemical vapor deposition (HFCVD) technique using two different boron concentrations. The growth parameters were controlled to obtain heavily doped diamond films. They were named as E1 and E2 electrodes, with acceptor concentrations of 4.0 and 8.0
×
10
21
atoms
cm
−3, respectively. The boron levels were evaluated from Mott–Schottky plots also corroborated by Raman's spectra, which characterized the film quality as well as its physical property. Scanning Electron Microscopy showed well-defined microcrystalline grain morphologies with crystal orientation mixtures of (1
1
1) and (1
0
0). The electrode efficiencies were studied from the advanced oxidation process (AOP) to degrade electrochemically the Reactive Orange 16 azo-dye (RO16). The results were analyzed by UV/VIS spectroscopy, total organic carbon (TOC) and high-performance liquid chromatography (HPLC) techniques. From UV/VIS spectra the highest doped electrode (E2) showed the best efficiency for both, the aromaticity reduction and the azo group fracture. These tendencies were confirmed by the TOC and chromatographic measurements. Besides, the results showed a direct relationship among the BDD morphology, physical property, and its performance during the degradation process.
•The treatment with boron-doped diamond anodes is able to completely degrade imazapyr.•The wastewater toxicity can be reduced by electrochemical treatment.•The major degradation intermediates are ...detected and identified by LC–MS/MS analyses.•Formic, acetic and butyric acids are the main non aromatic by-products.
In this work we have studied the treatment of imazapyr by electrochemical oxidation with boron-doped diamond anode. Electrochemical degradation experiments were performed in a one-compartment cell containing 0.45L of commercial formulations of herbicide in the pH range 3.0–10.0 by applying a density current between 10 and 150mAcm−2 and in the temperature range 25–45°C. The maximum current efficiencies were obtained at lower current densities since the electrochemical system is under mass transfer control. The mineralization rate increased in acid medium and at higher temperatures. The treatment was able to completely degrade imazapyr in the range 4.6–100.0mgL−1, although the current charge required rises along with the increasing initial concentration of the herbicide. Toxicity analysis with the bioluminescent bacterium Vibrio fischeri showed that at higher pollutant concentrations the toxicity was reduced after the electrochemical treatment. To clarify the reaction pathway for imazapyr mineralization by OH radicals, LC–MS/MS analyses we performed together with a theoretical study. Ions analysis showed the formation of high levels of ammonium in the cathode. The main final products of the electrochemical oxidation of imazapyr with diamond thin film electrodes are formic, acetic and butyric acids.
► The concentration of TBH was reduced by 90% following electrolysis with BDD/Ti. ► Electrolysis with BDD/Ti electrodes led to the removal of 80% of total organic carbon. ► The reduction and ...formation of the byproducts of TBH could be monitored by HPLC. ► Ion chromatography confirmed that the electrochemical breakdown of TBH with BDD/Ti. ► The least doped BDD was the more efficient.
The thiadiazolylurea derivative tebuthiuron (TBH) is commonly used as an herbicide even though it is highly toxic to humans. While various processes have been proposed for the removal of organic contaminants of this type from wastewater, electrochemical degradation has shown particular promise. The aim of the present study was to investigate the electrochemical degradation of TBH using anodes comprising boron-doped (5000 and 30000ppm) diamond (BDD) films deposited onto Ti substrates operated at current densities in the range 10–200mAcm−2. Both anodes removed TBH following a similar pseudo first-order reaction kinetics with kapp close to 3.2×10−2min−1. The maximum mineralization efficiency obtained was 80%. High-pressure liquid chromatography with UV–VIS detection established that both anodes degraded TBH via similar intermediates. Ion chromatography revealed that increasing concentrations of nitrate ions (up to 0.9ppm) were formed with increasing current density, while the formation of nitrite ions was observed with both anodes at current densities ⩾150mAcm−2. The BDD film prepared at the lower doping level (5000ppm) was more efficient in degrading TBH than its more highly doped counterpart. This unexpected finding may be explained in terms of the quantity of impurities incorporated into the diamond lattice during chemical vapor deposition.
The production, characterization, and application of boron doped diamond grown on titanium substrates (BDD/Ti) are proposed in a systematic study taking into account the optimized parameters to ...produce high quality electrodes in a suitable doping level applied in the electrooxidation of the Brilliant Green dye. The process efficiency was analyzed as a function of the BDD doping levels as well as their sp2 hybridization content in the film structures. A large set of sixteen BDD/Ti samples were applied in the electrooxidation experiments at constant current density of 100mAcm−2, using 100mgL−1 of the Brilliant Green dye in K2SO4 0.1molL−1 solution for 300min. The electrooxidation efficiency in the whole sample set was analyzed by UV/VIS Spectrophotometry and by Total Organic Carbon techniques considering the influence of the electrode characteristics in the degradation process. The results showed that all the electrodes were efficient in the solution discolorization and in the organic compound mineralization. However, BDD/Ti electrode with the lowest sp2 content associated to the intermediate doping level presented the best results. A mechanist route for the dye degradation was proposed, using the normalized parameters for the best BDD electrode, from high performance liquid chromatography — mass spectroscopy analyses.
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•Optimized parameters to produce high quality BDD to apply in electrooxidation•Advantages to use BDD for electrochemical advanced oxidation process•We report the sp2 bonds influence on BDD electrochemical response.•Mechanistic aspects in the Brilliant Green dye degradation using BDD electrodes
Supercapacitors have been studied due to their promising as powerful storage devices. The development of highly efficient electrodes is one way to manufacture supercapacitors with high energy and ...power efficiencies. Binary composites based on activated carbon fiber felt (ACFF) and polypyrrole (PPy) have been investigated to increase capacitance performance. ACF, when applied as a bulk electrode has limited electric characteristics while the PPy suffers from limited stability during cycling that reduces the initial performance. Based on the synergism effect, this work proposes the production of a binary composite based on ACFF produced from a low-cost precursor textile polyacrylonitrile (textile PAN) and the facile synthesis of PPy from the chemical route of polymerization. The binary composite formed by a 3D network with the interconnection of a more conductive form of PPy coated on ACFF was obtained. The resulting architecture was determinant to significantly increase the energy storage capacities when compared to the bulk ACFF electrode. From the galvanostatic charge and discharge curves, cyclic voltammetry and electrochemical impedance, the obtained composite had a specific capacitance about 302 F g
−1
associated with low resistance and to a good density of energy and power.
: Post-cardiotomy cardiogenic shock (PCCS), which is defined as severe low cardiac output syndrome after cardiac surgery, has a mortality rate of up to 90%. No study has yet been performed to compare ...patients with PCCS treated by conservative means to patients receiving additional mechanical circulatory support with veno-arterial extracorporeal membrane oxygenation (ECMO).
: A single-center retrospective analysis from January 2018 to June 2022 was performed.
: Out of 7028 patients who underwent cardiac surgery during this time period, 220 patients (3%) developed PCCS. The patients were stratified according to their severity of shock based on the Stage Classification Expert Consensus (SCAI) group. Known risk factors for shock-related mortality, including the vasoactive-inotropic score (VIS) and plasma lactate levels, were assessed at structured intervals. In patients treated additionally with ECMO (
= 73), the in-hospital mortality rate was 60%, compared to an in-hospital mortality rate of 85% in patients treated by conservative means (non-ECMO;
= 52). In 18/73 (25%) ECMO patients, the plasma lactate level normalized within 48 h, compared to 2/52 (4%) in non-ECMO patients. The morbidity of non-ECMO patients compared to ECMO patients included a need for dialysis (42% vs. 60%), myocardial infarction (19% vs. 27%), and cerebrovascular accident (17% vs. 12%).
: In conclusion, the additional use of ECMO in PCCS holds promise for enhancing outcomes in these critically ill patients, more rapid improvement of end-organ perfusion, and the normalization of plasma lactate levels.
Electrochemical response of nitrate reduction was analyzed using Boron Doped Diamond (BDD) films grown with different boron levels and it was correlated with the electrode physico-chemical ...properties. X-ray photoelectron spectroscopy and contact angle measurements showed the evolution of oxygen content and the weattability associated to the chemical surface modification as boron content increase in such films. Raman spectroscopy showed that the broad peaks at 1220 and 500
cm
−1 become more evident with the boron addition. Electrochemical measurements by square wave voltammetry for nitrate reduction showed a strong dependence between the doping level of the BDD film and the nitrate detection. BDD film grown with B/C ratio of 20,000
ppm presented the best sensibility to low concentration of nitrate. This result was analyzed from the linear relationship between the peak currents as a function of the nitrate concentration. This behavior was attributed to the changes in the diamond surface chemical and the film grain size.
A study of the electrochemical degradation of profenofos in a flow reactor with electrodes comprising boron-doped diamond films deposited on titanium substrate (BDD/Ti) as anodes has been performed. ...The BDD films were produced at growth times of 7 and 24h with similar B/C ratios corresponding to acceptor concentrations of around 1020atomscm−3. The morphological and structural characteristics of the BDD/Ti electrodes were evaluated by scanning electron microscopy and Raman scattering spectroscopy. Degradation experiments were carried out with applied current densities in the range 10 to 200mAcm−2 and flow rates of 50 and 300Lh−1. The rates of degradation of profenofos were evaluated by high performance liquid chromatography and variations in total organic carbon (TOC) were monitored during the electrochemical process in order to determine the level of mineralization of organic compounds present in the electrolyte. Under the best conditions (anode comprising a BDD film deposited on titanium for 7h and reactor operating at a flow rate of 300Lh−1) more than 95% of the profenofos was degraded and approximately 87% of TOC was removed within 120min of reaction time.
► Electrochemical degradation of profenofos using boron-doped diamond electrodes ► Influence of the diamond morphology in the profenofos degradation ► Systematic HPLC analysis of the profenofos degradation to optimize the process
The modification of surface bond termination promoted by the doping level on diamond electrodes is analyzed. The films were prepared by hot filament chemical vapor deposition technique using the ...standard mixture of H2/CH4 with an extra H2 flux passing through a bubbler containing different concentrations of B2O3 dissolved in methanol. Diamond morphology and quality were characterized by scanning electron microscopy and Raman scattering spectroscopy techniques while the changes in film surfaces were analyzed by contact angle, cyclic voltammetry and synchrotron X-ray photoelectron spectroscopy (XPS). The boron-doped diamond (BDD) films hydrophobicity, reversibility, and work potential window characteristics were related to their physical properties and chemical surface, as a function of the doping level. From the Mott–Schottky plots (MSP) and XPS analyzes, for the lightly (1018cm−3) and highly (1020cm−3) BDD films, the relationship between the BDD electrochemical responses and their surface bond terminations is discussed.
► Two boron doped diamond films were grown with different doping levels. ► Different electrochemical response between the samples was observed. ► There was a direct relationship between the measurements of XPS, electrochemical and contact angle. ► The doping process results in different chemical terminations. ► The doping process affects the band diagram result in NEA or PEA.
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