TRATAMIENTO ELECTROQUIMICO DE CONTAMINANTES ORGANOCLORADOS ALIFATICOS. ELUCIDACION DE LOS CAMINOS DE REACCION.

Los hidrocarburos alifáticos clorados conjugan toxicidad con una alta estabilidad química, capacidad de bioacumulación y difusión de largo alcance. Los cloroetanos son particularmente ubicuos en la industria y en los productos domésticos, y su introducción en el medio ambiente puede entrañar riesgos para los seres vivos. Actualmente, la USEPA (US Environmental Protection Agency) está llevando a cabo el llamado “Endocrine Disruptor Screening Program (EDSP)”, en el cual tanto el 1,2-dicloroetano (DCA) como el 1,1,2,2-tetracloroetano (TCA) son considerados prioritarios debido a sus efectos potenciales sobre el sistema endocrino. El DCA se encuentra también en la lista de substancias prioritarias establecida recientemente por la Comisión Europea.1 Para evitar o, cuando menos, minimizar la entrada de cloroetanos en el medio acuático es necesaria la aplicación de tecnologías de tratamiento de aguas más eficaces que las tradicionalmente empleadas en las plantas de tratamiento de aguas residuales, como por ejemplo los procesos de oxidación avanzada (AOPs). De entre éstos, los AOPs electroquímicos (EAOPs) como la oxidación anódica (OA) y el proceso electro-Fenton (EF) vienen suscitando un gran interés para la degradación de compuestos orgánicos debido a sus excepcionales características técnicas y al uso reducido de compuestos químicos de elevado coste. Sin embargo, hasta la fecha, la electrorreducción con cátodos de plata ha sido el método electroquímico más utilizado para la destrucción de cloroetanos, observándose en general una conversión parcial de los contaminantes iniciales en lugar de su mineralización total. En este trabajo, se han tratado disoluciones acuosas ácidas de DCA y TCA mediante los procesos EF y OA. Las electrólisis se han realizado a corriente constante usando un ánodo de diamante dopado con boro (BDD) y un cátodo a difusión de aire (ADE) capaz de generar H2O2 in situ, el cual reacciona con el Fe2+ añadido para obtener •OH en el seno de la disolución a partir de la conocida reacción de Fenton. A los 420 min de tratamiento EF a 300 mA, se alcanzó la mineralización prácticamente total de disoluciones con 4 mM de DCA o TCA. Tratamientos comparativos en ausencia de Fe2+ (es decir, OA) o con un ánodo de menor poder oxidante como el Pt condujeron a una mineralización más pobre. Los resultados tan positivos obtenidos mediante el proceso EF con BDD se pueden atribuir a la acción sinérgica de los radicales oxidantes, es decir, BDD(•OH) en la superficie del ánodo y •OH en el seno de la disolución, además de la minimización de las limitaciones difusivas. El descenso de la concentración del contaminante inicial se ajusta perfectamente a una cinética de pseudo primer orden. Los subproductos acumulados en mayor concentración durante la degradación del DCA y el TCA son los ácidos cloroacético y dicloroacético, respectivamente. Así mismo, se han identificado los ácidos acético, oxálico y fórmico. Los caminos de reacción propuestos incluyen etapas de decloración oxidativa y reductiva (catódica). Por otra parte, se ha encontrado que el cloro se libera inicialmente como ion Cl, el cual es oxidado a ion ClO3 y, fundamentalmente, a ion ClO4, gracias a la acción de los radicales BDD(•OH) y •OH generados en gran proporción. En conclusión, se ha demostrado que el proceso EF con una celda BDD/ADE es una tecnología muy efectiva para la descontaminación de disoluciones acuosas de DCA y TCA, así como de mezclas de ambos, lo cual constituye un resultado importante de cara a proseguir con su tratamiento en matrices de agua real. Referencias 1. European Commission, Identification of Priority Hazardous Substances under the Water Framework Directive, Directorate-General Environment, 2000

A comparison of electrochemical degradation of phenol on boron doped diamond and lead dioxide anodes

This work compares two electrode materials used to mineralize phenol contained in waste waters. Two disks covered with either boron doped diamond (BDD) or PbO2 were used as anodes in a one compartment flow cell under the same hydrodynamic conditions. Efficiencies of galvanostatic electrolyses are compared on the basis of measurements of Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD). Galvanostatic electrolyses were monitored by analysis of phenol and of its oxidation derivatives to evaluate the operating time needed for complete elimination of toxic aromatics. The experimental current efficiency is close to the theoretical value for the BDD electrode. Other parameters being equal, phenol species disappeared at the same rate using the two electrode materials but the BDD anode showed better efficiency to eliminate TOC and COD. Moreover, during the electrolysis less intermediates are formed with BDD compared to PbO2 whatever the current density. A comparison of energy consumption is given based on the criterion of 99% removal of aromatic compounds

Placental exosomes profile in maternal and fetal circulation in intrauterine growth restriction - Liquid biopsies to monitoring fetal growth

INTRODUCTION: Placenta-derived exosomes may represent an additional pathway by which the placenta communicates with the maternal system to induce maternal vascular adaptations to pregnancy and it may be affected during Fetal growth restriction (FGR). The objective of this study was to quantify the concentration of total and placenta-derived exosomes in maternal and fetal circulation in small fetuses classified as FGR or small for gestational age (SGA). METHODS: Prospective cohort study in singleton term gestations including 10 normally grown fetuses and 20 small fetuses, sub-classified into SGA and FGR accordingly to birth weight (BW) percentile and fetoplacental Doppler. Exosomes were isolated from maternal and fetal plasma and characterized by morphology, enrichment of exosomal proteins, and size distribution by electron microscopy, western blot, and nanoparticle tracking analysis, respectively. Total and specific placenta-derived exosomes were determined using quantum dots coupled with CD63+ve and placental-type alkaline phosphatase (PLAP)+ve antibodies, respectively. RESULTS: Maternal concentrations of CD63+ve and PLAP+ve exosomes were similar between the groups (all p > 0.05). However, there was a significant positive correlation between the ratio of placental-derived to total exosomes (PLAP+ve ratio) and BW percentile, [rho = 0.77 (95% CI: 0.57 to 0.89); p = 0.0001]. The contribution of placental exosomes to the total exosome concentration in maternal and fetal circulation showed a significant decrease among cases, with lower PLAP+ve ratios in FGR compared to controls and SGA cases. DISCUSSION: Quantification of placental exosomes in maternal plasma reflects fetal growth and it may be a useful indicator of placental function

Electrochemical synthesis of peroxomonophosphate using boron-doped diamond anodes

A new method for the synthesis of peroxomonophosphate, based on the use of boron-doped diamond electrodes, is described. The amount of oxidant electrogenerated depends on the characteristics of the supporting media (pH and solute concentration) and on the operating conditions (temperature and current density). Results show that the pH, between values of 1 and 5, does not influence either the electrosynthesis of peroxomonophosphate or the chemical stability of the oxidant generated. Conversely, low temperatures are required during the electrosynthesis process to minimize the thermal decomposition of peroxomonophosphate and to guarantee significant oxidant concentration. In addition, a marked influence of both the current density and the initial substrate is observed. This observation can be explained in terms of the contribution of hydroxyl radicals in the oxidation mechanisms that occur on diamond surfaces. In the assays carried out below the water oxidation potential, the generation of hydroxyl radicals did not take place. In these cases, peroxomonophosphate generation occurs through a direct electron transfer and, therefore, at these low current densities lower concentrations are obtained. On the other hand, at higher potentials both direct and hydroxyl radical-mediated mechanisms contribute to the oxidant generation and the process is more efficient. In the same way, the contribution of hydroxyl radicals may also help to explain the significant influence of the substrate concentration. Thus, the coexistence of both phosphate and hydroxyl radicals is required to ensure the generation of significant amounts of peroxomonophosphoric acid

Multicenter prospective clinical study to evaluate children short-term neurodevelopmental outcome in congenital heart disease (children NEURO-HEART): study protocol.

BACKGROUND: Congenital heart disease (CHD) is the most prevalent congenital malformation affecting 1 in 100 newborns. While advances in early diagnosis and postnatal management have increased survival in CHD children, worrying long-term outcomes, particularly neurodevelopmental disability, have emerged as a key prognostic factor in the counseling of these pregnancies. METHODS: Eligible participants are women presenting at 20 to < 37 weeks of gestation carrying a fetus with CHD. Maternal/neonatal recordings are performed at regular intervals, from the fetal period to 24 months of age, and include: placental and fetal hemodynamics, fetal brain magnetic resonance imaging (MRI), functional echocardiography, cerebral oxymetry, electroencephalography and serum neurological and cardiac biomarkers. Neurodevelopmental assessment is planned at 12 months of age using the ages and stages questionnaire (ASQ) and at 24 months of age with the Bayley-III test. Target recruitment is at least 150 cases classified in three groups according to three main severe CHD groups: transposition of great arteries (TGA), Tetralogy of Fallot (TOF) and Left Ventricular Outflow Tract Obstruction (LVOTO). DISCUSSION: The results of NEURO-HEART study will provide the most comprehensive knowledge until date of children's neurologic prognosis in CHD and will have the potential for developing future clinical decisive tools and improving preventive strategies in CHD

Benchmarking the scientific output of industrial wastewater research in Arab world by utilizing bibliometric techniques

Rapid population growth, worsening of the climate, and severity of freshwater scarcity are global challenges. In Arab world countries, where water resources are becoming increasingly scarce, the recycling of industrial wastewater could improve the efficiency of freshwater use. The benchmarking of scientific output of industrial wastewater research in the Arab world is an initiative that could support in shaping up and improving future research activities. This study assesses the scientific output of industrial wastewater research in the Arab world. A total of 2032 documents related to industrial wastewater were retrieved from 152 journals indexed in the Scopus databases; this represents 3.6 % of the global research output. The h-index of the retrieved documents was 70. The total number of citations, at the time of data analysis, was 34,296 with an average citation of 16.88 per document. Egypt, with a total publications of 655 (32.2 %), was ranked the first among the Arab countries followed by Saudi Arabia 300 (14.7 %) and Tunisia 297 (14.6 %). Egypt also had the highest h-index, assumed with Saudi Arabia, the first place in collaboration with other countries. Seven hundred fifteen (35.2 %) documents with 66 countries in Arab/non-Arab country collaborations were identified. Arab researchers collaborated mostly with researchers from France 239 (11.7 %), followed by the USA 127 (6.2 %). The top active journal was Desalination 126 (6.2 %), and the most productive institution was the National Research Center, Egypt 169 (8.3 %), followed by the King Abdul-Aziz University, Saudi Arabia 75 (3.7 %). Environmental Science was the most prevalent field of interest 930 (45.8 %). Despite the promising indicators, there is a need to close the gap in research between the Arab world and the other nations. Optimizing the investments and developing regional experiences are key factors to promote the scientific research

Electrochemical advanced oxidation processes (EAOPs) for environmental applications.

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