Synthetic wastewaters treatment by electrocoagulation to remove silver nanoparticles produced by different routes

International audienceNanoscience is a field that has stood out in recent years. The accurate long-term health and environmental risks associated with these emerging materials are unknown. Therefore, this work investigated how to eliminate silver nanoparticles (AgNPs) from synthetic effluents by electrocoagulation (EC) due to the widespread use of this type of nanoparticle (NP) in industry and its potential inhibition power over microorganisms responsible for biological treatment in effluent treatment plants. Synthesized AgNPs were studied via four different routes by chemical reduction in aqueous solutions to simulate the chemical variations of a hypothetical industrial effluent, and efficiency conditions of the EC treatment were determined. All routes used silver nitrate as the source of silver ions, and two synthesis routes were studied with sodium citrate as a stabilizer. In route I, sodium citrate functioned simultaneously as the reducing agent and stabilizing agent, whereas route II used sodium borohydride as a reducing agent. Route III used d-glucose as the reducing agent and sodium pyrophosphate as the stabilizer; route IV used sodium pyrophosphate as the stabilizing agent and sodium borohydride as the reducing agent. The efficiency of the EC process of the different synthesized solutions was studied. For route I, after 85 min of treatment, a significant decrease in the plasmon resonance peak of the sample was observed, which reflects the efficiency in the mass reduction of AgNPs in the solution by 98.6%. In route II, after 12 min of EC, the absorbance results reached the detection limit of the measurement instrument, which indicates a minimum reduction of 99.9% of AgNPs in the solution. During the 4 min of treatment in route III, the absorbance intensities again reached the detection limit, which indicates a minimum reduction of 99.8%. In route IV, after 10 min of treatment, a minimum AgNP reduction of 99.9% was observed. Based on these results, it was possible to verify that the solutions containing citrate considerably increased the necessary times required to eliminate AgNPs from the synthesized effluent, whereas solutions free of this reagent showed better results on floc formation and, therefore, are best for the treatment. The elimination of AgNPs from effluents by EC proved effective for the studied routes

Synthesis and characterization of Ag nanoparticles-conductive polyaniline composite powder material

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Superoxide Protonation by Weak Acids in Imidazolium Bases Iionic Liquids

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Acceleration of zinc corrosion in alkaline suspensions containing iron oxides or iron hydroxides

International audienceFast zinc dissolution is of industrial interest in recycling galvanised steel scraps. An acceleration of zinc corrosion in alkaline solutions was observed in the presence of various iron oxides or iron hydroxides. This corrosion was investigated by weight loss, measurements of hydrogen evolution and variation of current in a galvanic cell. The mechanism of this fast zinc corrosion was investigated by electrochemical means and by X-ray diffraction and scanning electron microscopy observations of zinc surface after immersion in alkaline suspensions of iron oxides or iron hydroxides. These insoluble iron compounds were involved in a reduction step leading to iron containing microparticles characterised by a low hydrogen overpotential and which acted as cathodic areas in a galvanic corrosion of zinc

A new highly sensitive micro-sensor for the ultra-traces analysis of paracetamol directly in water

International audienceIn the present work, a simple, inexpensive and highly sensitive electrochemical micro-sensor was developed for trace detection of paracetamol (PAR) directly in water, using electrochemical preconcentration technique (EP) on a cavity microelectrode modified with carbon black nanoparticles (nCB/ CME). The results demonstrate that with an EP of PAR on nCB/ CME at 0 V for 900 s in BRS 0.04 M at pH = 7, the new proposed micro-sensor show two large linear response in ranges of 5 × 10-10 to 9 × 10-8 mol.L-1 and from 1 × 10-7 to 1 × 10-6 mol.L-1. The detection and quantification limits are estimated to be 1.4 × 10-10 and 4.3 × 10-10 mol.L-1, respectively. The performances of the new proposed nCB/ CME for the determination of PAR were compared to its performances without EP and the results reveal the importance of the application of EP in improving the electroanalytical characteristics. The applicability of the designed micro-sensor was successfully applied for the direct analysis of local tap water and treated wastewater samples spiked with trace PAR compounds with a satisfactory recovery (less than 4 %) and a relation standard deviation less than 5 %. It indicates that the electrochemical micro-sensors are an effective device for monitoring PAR concentrations directly in water without any pretreatment. © 2022 Elsevier B.V

Radical-scavenging activity of two Algerian medicinal plants :Mentha spicata L. and Mentha pulegium L.

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Phenolic composition and antioxidant evaluation of Algerian mints extracts

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Study of the antioxidant activity and chromatographic profile of three Algerian plants belonging to the Ericaceae family

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Study of the antioxidant activity and chromatographic profile of three Algerian plants belonging to the Ericaceae family

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A new electrochemical sensor based on carbon paste electrode/Ru(III) complex for determination of nitrite: Electrochemical impedance and cyclic voltammetry measurements

International audienceThe modified carbon paste electrode with Ru(III) complex was studied as a novel sensor for the determination of nitrite. The behavior of NO2− at the electrode surface was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). EIS provided useful information on the charge transfer resistance (R) at the electrode/solution. The EIS measurements showed that R is low at oxidation potentials, and decreases with increasing temperature. The increase of the constant phase element with temperature is due to the accumulation of nitrite on the electrode, thus, facilitating the electron transfer between electrode and NO2−. CV was used to study the effect of pH on the electro-catalytic oxidation of NO2− and to determine the limit of detection (LOD). CV measurements showed a good linear relationship between the oxidation current and the concentration of NO2− over a wide concentration range 0–1.38 × 10−2 mol L−1. Low detection limit of 1.39 × 10−6 mol L−1 toward NO2− was obtained. LOD decreased by 23.2% compared to that determined using cavity microelectrode. © 2016 Elsevier Lt