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1. An integrated process for struvite electrochemical precipitation and ammonia oxidation of sludge alkaline hydrolysis supernatant.

Author

Zhou X and Chen Y

Subjects
Chemical Precipitation, Electrodes, Electrolysis, Hydrolysis, Magnesium chemistry, Nitrogen chemistry, Oxidation-Reduction, Phosphorus chemistry, Ammonia chemistry, Electrochemistry methods, Sewage chemistry, Struvite chemistry
Abstract

This study reported two-phase electrochemical processes, including struvite electrochemical precipitation and ammonia electrooxidation, for the treatment of supernatant from the hydrolysis sludge. The results showed that in phase I, the removal efficiencies of 92.3% PO 4 3- -P and 50.1% NH 4 + -N could be achieved in electrochemical precipitation with magnesium sacrificial anode at pH 9.0 and 40 mA after 120-min electrolysis, and slightly increased to 95.1% and 57.3%, respectively, when current further increased to 120 mA, while the energy consumption (ECS, from 0.6 to 6.7 kWh m -3 ) and specific energy consumption [SECS, from 2.7 to 29.9 Wh g (PO 4 3- -P) -1 ] sharply increased. In phase II, the residual NH 4 + -N is further indirectly electrooxidized to nitrogen with modified Ti anode (Ti/SnO 2 -Sb-Pd). With the generation of active chloride, about 83.2% NH 4 + -N was removed with the molar ratio of Cl/N 5:1 at 50 mA after 120-min treatment, and slightly increased to 92.2%, when current increased to 125 mA, while SECS significantly increased [from 0.027 to 0.117 kWh g (NH 4 + -N) -1 ]. The results indicated that current were the crucial factors; meanwhile, lower current and longer reaction time may be the optimal options in electrochemical process with higher efficiency and lower energy consumption. Finally, the integrated process was conducted at the optimal conditions (pH = 9.0, I = 40 mA in phase I; Cl/N = 5, I = 50 mA in phase II) with the supernatant of the alkaline hydrolysis sludge. Removal of ammonia nitrogen (79.3%) and removal of phosphorus (94.3%) were achieved, confirming the feasibility of practical application for the simultaneous phosphorus recovery and ammonia removal.

Published
2019
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2. Electrochemical sensor for the detection of estradiol based on electropolymerized molecularly imprinted polythioaniline film with signal amplification using gold nanoparticles

Author

Cecilia Cristea, Nicole Jaffrezic-Renault, Anca Florea, Francis Vocanson, Robert Săndulescu, Interfaces & biosensors - Interfaces & biocapteurs, Institut des Sciences Analytiques (ISA), Institut de Chimie du CNRS (INC)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Université Cluj-Napoca, facultatea, Laboratoire Hubert Curien [Saint Etienne] (LHC), Institut d'Optique Graduate School (IOGS)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), and 'This paper was published under the frame of European Social Found, Human Resources Development Operational Programme 2007-2013, project no. POSDRU/159/1.5/S/136893'.

Subjects
17-BETA-ESTRADIOL, 02 engineering and technology, Electrochemistry, 01 natural sciences, lcsh:Chemistry, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, Gold nanoparticles, Detection limit, Molecularly imprinted polymer, p-Aminothiophenol, Chromatography, Estradiol, Chemistry, 010401 analytical chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Electrochemical gas sensor, Linear range, lcsh:Industrial electrochemistry, lcsh:QD1-999, Colloidal gold, Linear sweep voltammetry, POLYMERS, 0210 nano-technology, Selectivity, [CHIM.OTHE]Chemical Sciences/Other, lcsh:TP250-261
Abstract

A sensitive electrochemical molecularly imprinted sensor was developed for the detection of estradiol, by electropolymerization of p-aminothiophenol functionalized gold nanoparticles in the presence of estradiol as template molecule. The extraction of the template leads to the formation of cavities that are able to recognize and bind estradiol with high affinity. The performance of the developed sensor for the detection of estradiol was investigated by linear sweep voltammetry using a hexacyanoferrate/hexacyanoferrite solution as redox probe. The molecularly imprinted sensor exhibits a broad linear range, between 3.6 fM and 3.6 nM and a limit of quantification of 1.09 fM. Compared to the non-imprinted sensor, the imprinted sensor exhibits high affinity for the binding of estradiol. Moreover, selectivity studies, performed towards binding of testosterone, a hormone with similar chemical structure, proved high sensor selectivity. Furthermore, the molecularly imprinted sensor was applied for the analysis of spiked river samples with good recoveries. Keywords: Molecularly imprinted polymer, p-Aminothiophenol, Gold nanoparticles, Estradiol

Published
2015

3. Influence of the electrografting method on the performances of a flow electrochemical sensor using modified electrodes for trace analysis of copper (II)

Author

Cecilia Cristea, Robert Săndulescu, Cristelle Mériadec, Florence Geneste, Ionel Fizesan, Bogdan Feier, Soraya Ababou Girard, Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Cluj-Napoca, facultatea, Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), This paper was published under the frame of European Social Found, Human Resources Development Operational Programme 2007–2013, Project No. POSDRU/159/1.5/S/136893. The authors are also thankful for the financial support to 'Iuliu Hatieganu' University of Medicine and Pharmacy of Cluj-Napoca, for the research Grant 1491/8/28.01.2014 and for their help to Ioana Băjan, Ana Gui and Ioana Ionel, students of 'Iuliu Hatieganu' University of Medicine and Pharmacy, Faculty of Pharmacy., Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Copper detection, [CHIM.ORGA]Chemical Sciences/Organic chemistry, General Chemical Engineering, Electrografting, Inorganic chemistry, Open circuit preconcentration, chemistry.chemical_element, Electrochemistry, Copper, Analytical Chemistry, Electrochemical gas sensor, chemistry.chemical_compound, chemistry, Electrode, Cyclam, Graphite, Cyclic voltammetry, Voltammetry, Sensor
Abstract

The performances of carboxylate- and cyclam-modified graphite felt electrodes prepared by different electrografting methods for trace analysis of copper (II) were compared to determine the influence of the immobilization process of the linkers on the sensor properties. The derivatization performed by cathodic reduction of diazonium salts and by anodic oxidation of amines in organic and aqueous media was first evaluated by cyclic voltammetry and X-ray photoelectron spectroscopy analyses, showing a higher surface coverage for the reduction process. Cyclam was subsequently attached on the COOH-modified graphite felts by a coupling reaction. The modified electrodes were then employed in a flow analytical system for trace analysis of copper (II) ions. The influence of the surface coverage and the nature of the linker on the electrochemical signal obtained by linear sweep stripping voltammetry analysis after a preconcentration step performed at open circuit was highlighted. The selectivity estimated in the presence of lead used as a common ion interferent was higher when a selective receptor was used and depends on the nature of the linker.

Published
2015