•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.
► 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.
1. This work investigates the apparent metabolisable energy (AME), its nitrogen-corrected form (AMEn) and amino acid (AA) digestibility coefficients of the microalgae Spirulina platensis as an ...ingredient in broiler chicken diets.
2. One group of birds was fed with a basal control diet (BD), and another was fed with a test diet composed of the BD with the addition of the microalgae at a proportion of 200 g/kg. AME and AMEn were assessed by total excreta collection and indigestibility analysis using acid-insoluble ash (AIA) as a marker.
3. The microalgae comprised 888.0 g/kg dry matter (DM), 18.42 MJ/kg gross energy, 514.7 g/kg crude protein, 9.9 g/kg ether extract, 10.6 g/kg crude fibre, 94.4 g/kg ash, 3.1 g/kg Ca and 11.0 g/kg P.
4. The values obtained for AME (13.48 MJ/kg DM) and AMEn (11.72 MJ/kg DM) were higher (p < 0.01) than those obtained using the AIA method (9.39-8.29 MJ/kg DM). The microalgae ileal digestibility coefficients were 0.80 ± 0.04 and 0.78 ± 0.04 for essential and non-essential AA, respectively.
5. Overall, the metabolisable energy content and digestibility of AA for S. platensis indicated that the microalgae are potentially an alternative nutrient source for broilers. The AIA method underestimated AME and AMEn in comparison to the total excreta collection method.
► 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
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
Copper (Cu) electrodeposition and photoelectrodeposition on highly boron-doped diamond films (BDD) were investigated, at two different pH solutions. Cu particles were deposited in the potentiostat ...mode and under UV irradiation. The as-grown as well as the Cu modified BDD films were characterized by Raman Spectroscopy and Scanning Electron Microscopy. The copper photocatalytic deposition on BDD was discussed taking into account the influence of the photogenerated electrons for photoelectrodeposition process at both acid and neutral pH solutions. Under UV irradiation, the copper deposits presented higher density and uniformity all over the crystal faces when compared with those without UV irradiation. This behavior may be attributed to BDD semiconductor character due to its photogenerated electrons which enhanced the copper reduction reaction.
•Electrodeposition and photoelectrodeposition of copper on boron-doped diamond were obtained.•The influence of the photogenerated electrons to understand the cooper on the diamond film was discussed.•The cooper deposited presented high density and uniformity all over the crystal.
The ν-Angra experiment has developed an antineutrino detector intended to operate at sea level, a few dozen meters from the core of a nuclear reactor. The operating principle of the detector is based ...on the water Cherenkov light detection to be in compliance with the safety rules of the power plant operator. The detector is exposed to a high rate of background events, mainly due to cosmic rays, making its veto system a key element for efficient background rejection. The ν-Angra Collaboration has designed a veto detector composed of three layers filled with water for both passive shielding and active detection of crossing particles. The veto surrounds a volume of 1.50 × 1.05 × 1.39 m3, in which a target detector is placed, where the search for anti-neutrino events occurs. Any external particle hitting the detector must cross at least 25 cm of water before reaching this internal volume, which is protected by the veto structure, thus providing an important barrier against neutrons and low energy particles. In addition, the veto system has been instrumented with eight 8-inch photomultiplier tubes to detect external particles that may eventually reach the target detector. By making use of a trigger system based on scintillating paddles, energy distribution and detection efficiency of the veto system were assessed for different detector positions. This paper, therefore, presents the achieved results related to the characterization of such system concerning the detection of cosmic-ray muon particles passing through it.
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