Papers by Ioannis Ignatiadis
Science of The Total Environment, Mar 1, 2020
International Journal of Multiphase Flow, Apr 1, 2022
Science of The Total Environment, Mar 1, 2021
Le comportement electrochimique a la corrosion de l'acier au carbone api k55 dans le fluide g... more Le comportement electrochimique a la corrosion de l'acier au carbone api k55 dans le fluide geothermal a ete etudie en presence et en l'absence de differents inhibiteurs a base d'amines, potentiellement adaptes aux problemes de corrosion-depot dans les installations geothermiques exploitant l'aquifere du dogger du bassin parisien. La conjugaison des travaux effectues au laboratoire et sur sites, sous differentes conditions physico-chimiques et d'exploitation, nous ont permis de comprendre l'action des differents parametres reconnus comme determinants dans les processus de corrosion tels que, la concentration en sulfure d'hydrogene et en ions chlorures, le debit d'exploitation et les depots de sulfures de fer. Le sulfure d'hydrogene active les reactions anodiques et cathodiques dans le domaine de concentration explore (0-100 mg/l), l'augmentation de sa concentration reduit l'efficacite des inhibiteurs organiques de corrosion. Les ions chlorures augmentent l'agressivite du fluide dans les milieux faiblement agites et reduisent l'efficacite des inhibiteurs a base d'ammonium quaternaires. L'augmentation du debit reduit la vitesse de corrosion ainsi que l'epaisseur des depots de corrosion. Les depots de corrosion sont majoritairement constitues de sulfures de fer et se presentent sous forme de deux couches distinctes: la premiere, mince, du cote metal est formee d'hydroxydes et d'hydroxychlorures de fer et la seconde externe plus epaisse et constituee majoritairement de sulfures de fer. Ces depots, poreux et plus nobles que le fer, ne sont pas protecteurs et peuvent participer a l'activation de la corrosion par transfert des sites cathodiques sur leur surface. La cinetique de corrosion de l'acier au carbone dans ce milieu est sous controle mixte, transfert diffusion. Les inhibiteurs de corrosion testes presentent une efficacite satisfaisante. L'amine grasse est l'inhibiteur le plus adapte, puisque son efficacite n'est alteree ni par la presence des depots, ni par un milieu stagnant ou agite, sa forte vitesse d'adsorption ainsi que son faible caractere anodique diminuent le risque de corrosion par piqures. Pour l'investigation de formulations inhibitrices, deux series de tests electrochimiques sont proposees. Elles permettent de definir les conditions optimales de l'utilisation de l'acier au carbone (et de tout autre materiau metallique) dans un milieu corrosif donne et le choix de l'inhibiteur adapte
HAL (Le Centre pour la Communication Scientifique Directe), Apr 16, 2013
Today, reductive dehalogenation (RDH), using strong reducers, is one of the most important emergi... more Today, reductive dehalogenation (RDH), using strong reducers, is one of the most important emerging remediation techniques for halogenated hydrocarbons (HHC). The use of nanomaterials, all alone or coupled with strong reducers, for RDH is emerging too as a good alternative and promising technological approach to clean up polluted environments by HHC. The purpose of the present study was to set up an enhanced monitoring of the reductive dechlorination (RDC) of Perchlorethylene (PCE) in soils, based on geophysical and electrochemical measurements and practiced, at this stage, only in columns. This study is accomplished within the framework of DECHLORED, a project that aims to clean up aquifers by using strong reducers with or not the combined effect of Nano-iron particles (NIP), reaching the RDC of chlorinated hydrocarbons (CHC) and illuminating the field under RDC process. For this purpose, columns (height 50cm; diameter 20cm) are designed and made in Kynar® and equipped with sophisticated systems for non-destructive monitoring of time changing physical parameters. This monitoring was complemented by physicochemical probes (temperature, pH, redox, conductivity, oxygen and chloride) and Gas Chromatography for PCE and its degradation products (DCE, ethene and ethane) and Ion Chromatography for Cl- and SO42- in water at the column output to correlate RDC, NP migration and electrical properties. The entire system was placed in air-conditioned cupboard. Columns are implemented with two rings of Hasteloy® as electrodes for alternative sinusoidal current (AC) injection and six ports equipped with Ag-AgCl electrodes for potential measurement. Two methods are used: i) frequency-domain induced polarization (IP) measurements (which consist of imposing an AC current at a given frequency and measuring the resulting electrical potential difference between two other non-polarizing electrodes), and ii) galvanostatic electrochemical impedance spectroscopy (GEIS). Both by measuring complex electrical conductivity in the mHz to kHz range, are sensitive to electrolytic conductivity, grain surface conductivity and metallic conductivity. Under time varying electric field, pore fluid/solid polarization effects could be measured from surface using IP impedance analyzer or time-domain resistivimeter. Indeed, IP can map real and complex resistivities of the media at any time and particularly, before, during and after the RDC process application on the column. Two different soils, polluted or not by PCE, different solutions/suspensions of reactants (reducers or NIPs separately or reducers and NIPs together) at two different temperatures (12 and 25°C) are tried. Experiments in columns were carried out to test reactants behavior, in the absence and in the presence of PCE, and allow us to: * estimate how reactants and PCE chemical degradation products transform electrical properties * assess reactant dispersion, distribution, transport and reactivity on PCE degradation, inside the columns (over all its length) and as a function of time and for different soils * Improve understanding of reactant efficacy, their transformation and persistence, and also their potential negative effects * model these flow-through systems (1D or 2D column set up) by modeling softwares (PHREEQC® and MARTHE® reactive transport simulations). Our results claim for combining geophysical with electroanalytical measurements to monitor RDC processes and will allow us to give an advantageous method for monitoring and checking in situ remediation.
International Journal of Mineral Processing, May 1, 2001
HAL (Le Centre pour la Communication Scientifique Directe), Sep 2, 2018
HAL (Le Centre pour la Communication Scientifique Directe), Apr 18, 2013
The objective of the project ImPAC Lyon was to evaluate the thermal, physico-chemical and microbi... more The objective of the project ImPAC Lyon was to evaluate the thermal, physico-chemical and microbiological impacts potentially associated to a ground water heat pump. It is based on two experimental parts : one in laboratory and the other on land (8th district of Lyon). The main results indicate that : - On land, no physical and microbiological disturbances were able to be revealing in the conditions of the study (range of temperature : 16-24 °C). Only thermal disturbances were observed. - The bad sizing of the doublet (which seems significant of the practices in urban with few space) could leads thermal disturbances and a progressive heating of the aquifer in an interannual scale. In these conditions, it seems all the more necessary to pursue the works begun in Lyon by treating the other ranges of temperatures. - The experimental approach of laboratory displayed in this study (range of temperature: 15-25 °C) indicates a sure influence of the temperature on the native bacterial microflora, but not enough to compromise the ecosystem balance. However, the other conditions of environment have to be studied (T > 25 °C and T< 15 °C, different redox conditions). - Behavior of pathogenic bacteria and organic pollutants in front of thermal modifications were not able to be observed to Lyon (no pollutions observed). They will also have to be studied in new projects.
Applied environmental science and engineering for a sustainable future, 2020
Environmental remediation deals with the removal of pollutants from media such as soils, groundwa... more Environmental remediation deals with the removal of pollutants from media such as soils, groundwater, sediments, and surface water for the sake of human health and the environment. Organic contaminants constitute the main source of pollution. If the concentration of these contaminants is too high or their mobilities are very poor, conventional treatment techniques, namely physical, biological, and chemical treatments are not very efficient from the technological or economical standpoint. In these cases, thermal treatments can be applied. Thermal enhancements have been used for the remediation of contaminated soils and groundwater for more than 20 years. Depending on the heating temperatures, in situ thermal treatment may be used in combination with physical, chemical, and biological treatment processes. Increasing the temperature contributes to (1) increasing the organic contaminant vapor pressure, the aqueous solubility, the Henry’s Law constant, the rate of (bio)chemical degradation and (2) decreasing the organic carbon partitioning, liquid density, liquid viscosity, and interfacial tension. By changing these physicochemical properties, the remediation rates and yields increase, and eventually the pollution remediation time, and sometimes treatment costs are reduced. However, implementing these thermal treatment technologies is not applicable in all cases: it involves high-energy consumption by reaching high temperatures, and maybe further complicated by heat loss (depending on environmental conditions). In this chapter, conventional technologies for in situ thermal enhancements are discussed from the theoretical and practical viewpoints including steam-enhanced extraction, thermal conductive heating, and electrical resistance heating. The advantages and limitations of these technologies, as well as innovative techniques such as radio frequency heating are also debated in this chapter.
Materials Science Forum, 1993
Applied and Environmental Soil Science, 2016
Near-neutral pH and low redox potentials (EH) are considered favorable conditions for radionuclid... more Near-neutral pH and low redox potentials (EH) are considered favorable conditions for radionuclides immobilization in deep repository systems in clay geological formations. Cigeo is a future Industrial Centre for Geological Disposal for Nuclear Waste (NW) for high-level and intermediate level long-lived radioactive waste, to be built in France, at 500 m depth within the Callovo-Oxfordian clay formation. Deep knowledge of the mechanisms and kinetics of corrosion occurring at the external surface of tubings made of API 5L X65 carbon steel (CS-X65) in contact with COx pore water, is essential for a reversible NW management of the Cigeo site. By using robust handmade electrodes and electrochemical and gravimetric techniques, this work aimed to determine the corrosion phenomenology and kinetics of CS-X65 in contact with COx pore water flowing continuously through a Multi-Parameter Probe (MPP) device, placed at 500 m depth, for more than 180 days. It also aimed at demonstrating the reliability and the robustness of the measurement methodology for the corrosion evaluation of the metallic liner of the future nuclear waste disposal site. Two iron oxidants were encountered, oxygen, who was depleted, and proton, who was accompanied by hydrogen sulfide. Corrosion mechanisms and kinetics were well established for two CS-X65, electrochemically perturbed and not. The corrosion thickness loss rates stand between 0.016 and 0.032 mm/y.
Journal of Chromatography A, 1986
Abstract Non-basic nitrogen-containing polyaromatic hydrocarbons (NPAHs) were determined in a hyd... more Abstract Non-basic nitrogen-containing polyaromatic hydrocarbons (NPAHs) were determined in a hydrotreated coker gas oil using gas chromatography and combined gas chromatography—mass spectrometry. The abundant NPAHs are alkylated benzologues of carbazole. The relative distribution of the carbazole derivatives in the sample is characterized by the presence of alkylcarbazoles with up to four carbon atoms in the substituents and alkylbenzocarbazoles branched by chains with two carbon atoms or less. Substances with polymethyl structures are the most abundant. Although severe hydrotreating conditions were applied to the feedstock, the observed NPAHs could not be eliminated. Their resistance is probably a function of the position of the alkyl groups on the aromatic nuclei.
Biosensors and Bioelectronics, Aug 1, 2006
Journal of Chromatography A, 1987
ABSTRACT Two procedures are described for the determination of sulphur-containing polynuclear aro... more ABSTRACT Two procedures are described for the determination of sulphur-containing polynuclear aromatic hydrocarbons (SPAHs) in petroleum and in its derived industrial products. As a general clean-up procedure, the total aromatic fractions were obtained after partition of the sample between dimethyl sulphoxide (DMSO) and pentane, followed by liquid—liquid extraction of the DMSO layer. In the first method, SPAHs were oxidized to sulphones, isolated selectively and back-reduced to SPAHs. The second approach was the direct determination of SPAHs in the aromatic fractions from the clean-up, by gas chromatography with selective detection using a flame photometric detector and gas chromatography—mass spectrometry with selected ion monitoring.The determination of SPAHs in four crude oils and a coker gas oil is reported. The various isomers are assumed to have been formed in sediments by random alkylation and degradation mechanisms, although specific substances with an increased stability compared with that of other isomers accumulated preferentially.For dibenzothiophene congeners, the number of GC peaks observed in a capillary column chromatogram is close to the maximum number of peaks that could be observed, as predicted by the statistical theory of Giddings. For benzothiophene congeners, the observed number is smaller. SPAHs are concluded to result from severe transformation mechanisms of the organic precursors occurring in sediments.
Chromatographia, Mar 1, 1987
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Papers by Ioannis Ignatiadis