Comment on "Competitive Adsorption of Cd(II), Cr(VI), and Pb(II) onto Nanomaghemite: A Spectroscopic and Modeling Approach"

International audienceno abstrac

Photocatalytic degradation of binary and ternary mixtures of antibiotics reactive species investigation in pilot scale

International audienceThe present study investigates the photocatalytic degradation of three quinolone antibiotics (i.e., Flumequine (FLU), Oxolinic Acid (OA) and Nalidixic Acid (NA)) in mono-, binary and ternary compound systems. The closed-loop step photo-reactor and TiO 2 impregnated on cellulosic paper as supported photo-catalyst in presence of UV light irradiation were used. The degradation of FLU occurred within 4 h. A 65.4% mineralization of OA was observed in a mono-compound system, due to the fast conversion of these main by-products formed. Besides, the investigation of the contribution of free radicals revealed the involvement of hole (h + ), O 2 •― , but mainly • OH on the degradation of OA. The second-order kinetic rate constants calculated relative to the contribution of • OH radicals on the degradation of OA was 4.03 × 10 9 M −1 s −1 , whereas for that of NA was 4.42 × 10 9 M −1 s −1 , thus underscoring that • OH is the primary reactive species implicated in the photocatalytic degradation of these compounds on TiO 2 /cellulosic paper catalysts. The mono-compound system shows a higher degradation rate compared to multi-compound system (binary and ternary) which explained by the competitive adsorption of antibiotics on the available active sites of photocatalyst surface. Overall, the constant photocatalytic rates are higher following this order mono-compound system andgt; ternary mixture andgt; binary mixture. The catalyst was characterized by mean of FTIR, HR-TEM and XRD. The SiO 2 -binder role was discussed in details based on the atomic distribution of elements on the cellulose fibers as shown by the EDS atomic mapping

Activation of persulfate by irradiated laterite for removal of fluoroquinolones in multi-component systems

International audienceAlthough several emerging contaminants (e.g. fluoro(quinolones) (FQs)) have been simultaneously detected in environmental systems, there is very limited information on their elimination from contaminated waters in multi-component systems. In this study, removal of three FQs including flumequine (FLU), ciprofloxacin (CIP) and norfloxacin (NOR) were investigated in single and mixture systems, using natural laterite soil and persulfate (PS) under UVA irradiation. Both sorption and oxidation reactions contribute to the removal of FQs from aqueous phase, whereas quenching experiments showed that SO4[rad]− is mainly responsible for the FQs oxidation. The kinetic rate constants can be ranked as follows: CIP andgt; NOR andgt; FLU, regardless of whether the compound was alone or in mixture. The higher degradation rate constant of CIP relative to those of NOR and FLU could be explained by the high reactivity of SO4[rad]− radical with cyclopropane-ring containing compounds. Fall in oxidation performance was observed in synthetic wastewater, probably due to sulfate radical scavenging by wastewater components. However, degradation rate constants of CIP in wastewater remains unchanged in mixture systems as compared to single ones. This environmentally friendly remediation technology may appear as a promising way for the removal of fluoroquinolone antibiotics from multi-contaminated waters

Use of laterite as a sustainable catalyst for removal of fluoroquinolone antibiotics from contaminated water

International audienceAlthough there is a growing interest in Fenton oxidation processes based on natural catalysts, the use of laterite soil to promote sequential adsorption/oxidation treatments of fluoroquinolone antibiotics has been scarcely investigated. In this work, the ability of an african laterite containing goethite and hematite to remove flumequine (FLU), used as a representative compound of fluoroquinolone antibiotics, was evaluated under dark and UVA irradiation. Batch experiments and liquid chromatography analyses showed that the presence of laterite can enhance FLU removal from heavily contaminated water through both sorption and oxidation reactions (up to 94% removal of 77 μmol L−1 of FLU and 72% of mineralization). The heterogeneous reaction rate is dominated by the rate of intrinsic surface chemical reactions including sorption and oxidation of FLU, and light-induced reduction of FeIII sites to produce FeII. Based on the probe and scavenging experiments, [rad]OH radicals were mainly involved in the heterogeneous oxidation reaction. The photo-assisted Fenton process showed a high efficiency of FLU removal even in the presence of a second fluoroquinolone antibiotic, norfloxacin (NOR), which can be co-found with FLU in affected environments. Determinations of kinetic rate constants and total organic carbon (TOC) for five sequential adsorption/oxidation cycles showed that laterite exhibited no deactivation of surface sites and an excellent catalytic stability. This cost-effective and environmentally friendly remediation technology may appear as a promising way for the removal of fluoroquinolone antibiotics from multi-contaminated waters. © 2017 Elsevier Lt

Recherche des hémoglobinopathies qualitatives chez les hémophiles à Abidjan, Côte d’Ivoire

Introduction : L’hémophilie est une maladie héréditaire rare à transmission récessive liée au chromosome X. Les principaux  symptômes sont l’hémorragie, les hématomes, l’anémie et les douleurs articulaires dans les hémarthroses. Ces deux derniers signespeuvent se retrouver au cours des hémoglobinopathies. Ainsi, l’objectif de cette étude était de rechercher la présence d’hémoglobinopathies qualitatives dans une cohorte d’hémophiles suivis au service d’hématologie clinique du CHU de Yopougon.Méthodes : C’est une étude transversale qui s’est déroulée de Janvier à Juillet 2017 au niveau de l’unité d’hématologie du laboratoire central du CHU de Yopougon. Sur les prélèvements de 49 patients, ont été effectués l’hémogramme, l’électrophorèse de l’hémoglobine, le taux de prothrombine (TP), le temps de céphaline activée (TCA) et le dosage des facteurs VIII et IX par la méthode chronométrique.Résultats : La moyenne d’âge était de 17 ans avec 73,5% d’élèves et étudiants. Les hémarthroses (75,5%) et les hématomes (36,7%) constituaient l’essentiel des signes cliniques. La complication majeure était la déformation articulaire à 34,7%. Sur les 49 patients constituant la cohorte, le pourcentage d’hémophiles A était de 89.8% (44/49) et celui d’hémophiles B 10,2% (5/49), avec 81,6% (40/49) d’hémophiles sévères. La fréquence des hémoglobinopathies qualitatives est de 8,2% (4/49) avec 6,2% de trait drépanocytaire AS (3/49) et 2% d’hémoglobine AC (1/49).Conclusion : Cette étude a mis en évidence la présence d’hémoglobinopathies qualitatives, pouvant coexister avec l’hémophilie, ce qui peut compliquer la prise en charge et la qualité de vie des patients. Mots clés : Hémophilie, hémogramme, électrophorèse, Abidjan.   English title: Research of qualitative haemoglobinopathies in hemophiliacs in Abidjan, Côte d’Ivoire Introduction: Hemophilia is a rare hereditary disease with X-linked recessive inheritance. The main symptoms are haemorrhage, hematoma, anemia and joint pain associated with hemarthrosis. These last two signs can also be found during haemoglobinopathies. Thus, the objective of this study was to investigate the presence of qualitative haemoglobinopathies in a cohort of hemophiliacs followed in the clinical hematology department of Yopougon University Hospital. Methods: This is a cross-sectional study that took place from January to July 2017 at the hematology unit of the central laboratory of the Yopougon University Hospital. On the samples of 49 patients, blood count, haemoglobin electrophoresis, prothrombin time (PT), activated partial thromboplastin time (APTT) and factor VIII and IX were measured by the chronometric method. Results: The average age was 17 with 73.5% of students. Haemarthrosis (75.5%) and hematoma (36.7%) constituted the bulk of clinical signs. The major complication was joint deformity with 34.7%. Of the 49 patients in the cohort, the proportion of hemophiliacs A was 89.8% (44/49) and that of hemophiliac B was 10.2% (5/49), with 81.6% (40/49) of all patients showing severe haemophilia. The frequency of qualitative haemoglobinopathies was 8.2% (4/49) with 6.2% of haemoglobin AS or sickle cell trait (3/49) and 2% of haemoglobin AC (1/49). Conclusion: This study highlighted the presence of qualitative hemoglobinopathies that can coexist with hemophilia, which can  complicate the management and quality of life of patients. Keywords: Hemophilia, hemogram, electrophoresis, Abidjan.  &nbsp

Colloidal and chemical stabilities of iron oxide nanoparticles in aqueous solutions: the interplay of structural, chemical and environmental drivers

International audienceNanoparticle (NP) stability in aqueous environments is dependent upon many parameters including environmental conditions, NP concentrations as well as NP intrinsic characteristics. In this study, the effects of pH and surface modifications on the colloidal and chemical stabilities of nanosized magnetite (Fe3O4), maghemite (γ-Fe2O3) and hematite (α-Fe2O3) are investigated. Because changes in surface charge affect the size distribution of NP, pH plays a key role in driving the colloidal stability. More NP aggregation is observed at pH values close to the pH of zero point of charge (pHzpc). Coating of magnetite with humic acid (HA) and phosphatidylcholine (PC) affects the electrostatic interactions and then the colloidal behavior of NP. The rapid transformation of magnetite into maghemite through air oxidation results in significant modification of both surface charge and specific surface area of NP. Because the maghemite almost exclusively formed µm-scale aggregates, the colloidal stability of magnetite is expected to be hindered in oxic environments. For hematite, the particle size distribution data emphasize the influence of both pH and intrinsic surface properties in the colloidal stability. These findings may have strong implications for an accurate prediction of the transformation and mobility of Fe-nanoparticles under environmentally relevant conditions and thus their fate in nature

Contrasted land-surface processes along the West African rainfall gradient

We review the main results of land-surface studies obtained in the three sites of the long-term observing system AMMA-CATCH. Runoff in the Sahel enhances the variability of energy partitioning between non-infiltrative areas where sensible heat is dominant and infiltrative areas where soil water availability increases the latent flux. In terms of water resources, an increase in runoff over the past 50 years, already reported for the exoreic Sahel, was revealed in the endoreic Sahel. In the Sudanian domain, the subsurface origin of streamflow could explain its decrease over the same period. Copyright © 2011 Royal Meteorological Society