Les composés dits 'bionano' (bionanocomposites) apparaissent comme un nouveau groupe de matériaux hybrides nano-structurés. Ils sont issus de la combinaison de polymères naturels et de solides inorganiques et sont de l'ordre du nanomètre dans au moins une direction. Ces matériaux hybrides conservent les structures et les propriétés fonctionnelles des polymères et matériaux inorganiques dont ils sont composés. Parallèlement, la présence de biopolymères permet de diminuer les risques environnementaux et de santés publiques liés aux nano-matériaux. Les propriétés inhérentes aux biopolymères (biocompatibles' et biodégradables) ouvrent des perspectives intéressantes pour ces matériaux hybrides en particulier dans les domaines de la médecine regénérative et en génie de l'environnement. La production de bionanocomposites de taille plus importante, que les nanoparticules qu'ils renferment, permet d'éviter les effets nocifs potentiels des nanoparticules (NPs) pour les organismes vivants et plus particulièrement pour l'homme. L'association de biopolymères et de nano-solides inorganiques permet la conception de bionanocomposites multifonctionnels qui peuvent être synthétisés et utilisés pour des applications dans des domaines variés. Cette thèse se propose d'étudier principalement (i) ma présence d'arsenic et d'antibiotiques dans les sources d'eau potable en Chine; (ii) l'évaluation d'un nouveau bionanocomposites, à savoir le CGB (chitosan goethite bionanocomposite), dans la décontamination des eaux contenant des espèces inorganiques d'arsenic; (iii) l'évaluation d'argiles comme adsorbants de décontamination de la gentamicine (un antibiotique aminoglycoside ) présent dans l'eau de même que celle de bionanocomposés fait d'argiles riches en gentamicine de polymères de methycelluloses hydroxypropyles Gt-Mt-HPMC (gentamicin-montmorillonite- hydroxypropyl methycellulose) utilisés comme pansement contre les infections qui ont lieu suite à des brûlures. / Bionanocomposites represent an emerging group of nano-structured hybrid materials. They are formed by the combination of natural polymers and inorganic solids and show at least one dimension on the nanometer scale (Darder et al., 2007). These hybrid materials retain the structural and functional properties of nano-structured materials. Meanwhile, the presence of biopolymer can reduce the public health and environmental risk of nano-sized material. The properties inherent to the biopolymers, that is, biocompatibility and biodegradability, open new prospects for these hybrid materials with special incidence in regenerative medicine and in environmental engineering (Darder et al., 2007). Fabrication of large-sized bionanocomposites, rather than nano-sized particles, can prevent possible harmful nanoparticles (NPs) intake by humans and living things. Synergistic assembling of biopolymers with inorganic nano-sized solids leads to multifunctional bionanocomposites which can be synthesized and applied in several areas for designed purposes. This thesis focuses on (i) the presence of toxic arsenic and antibiotics in Chinese drinking water sources; (ii) evaluation of a novel tailored bionanocompsite, namely chitosan goethite bionanocomposite (CGB), as removal agent for inorganic arsenic species from water; (iii) using clay mineral as adsorbent for removing gentamicin, an aminoglycoside antibiotic, from water, and assembling gentamicin-loaded clay with biopolymer hydroxypropyl methycellulose leading to a bionanocomposites film, namely gentamicin-montmorillonite- hydroxypropyl methycellulose (Gt-Mt-HPMC), to be used as burn wound dressing.

This research was directed at reducing arsenic levels in the effluents generated at the Canelands facility that manufactures monosodium methyl arsenate. Two effluent streams containing arsenic have to be considered, a raw water stream that is treated on site and a brine stream that is disposed of by sea outfall. Removal of arsenate from aqueous media by coagulation was investigated and models were developed describing selected variables that influence the removal of the arsenate. Three coagulant systems were investigated, namely aluminium(III) coagulation, iron(III) coagulation and binary mixtures of aluminium(III) and iron(III). Researchers have studied individual aluminium (III) sulphate and iron(III) chloride coagulation. No detailed research and modelling had, however, been carried out on the use of binary mixtures of aluminium (III) sulphate and iron (III) chloride coagulation of aqueous arsenate, nor had individual aluminium(III) sulphate and iron(III) chloride coagulation of arsenate been modelled at relatively high arsenate concentrations. The models that were generated were validated statistically and experimentally. The variables investigated in the aluminium(III) model included initial arsenate concentration, pH, polymeric flocculent concentration, aluminium(III) concentration and settling time. The variables modelled in the iron(III) coagulation were initial arsenate concentration, pH, polymeric flocculent concentration, and iron(III) to arsenic mole ratio. The modelling of the binary coagulant system included initial arsenate concentration, pH, iron (III) concentration, aluminium(III) concentration, and flocculent concentration as variables. The most efficient arsenic removal by coagulation was iron(III), followed by the binary mixture of aluminium(III) and iron(III) and the weakest coagulant was aluminium(III) sulphate. Scale-up coagulations performed on real raw water samples at a 50 litre volume showed that iron(III) was the most efficient coagulant (on a molar basis) followed closely by the binary mixture, while aluminium(III) coagulation was considerably weaker. The residual arsenic levels of the iron(III) and the binary coagulation systems met the effluent discharge criteria, but the aluminium coagulation system did not. Leaching tests showed that the iron(III) sludge was the most stable followed by the sludge of the binary mixture and the aluminium(III)-based sludge leached arsenic most readily. Settling rate studies showed that the flocs of the iron(III) coagulations settled the fastest, followed by binary mixture flocs and the aluminium flocs settled the slowest. The flocs of the binary mixture had the lowest volume, followed by the iron(III) flocs, while the aluminium(III) flocs were the most voluminous. Based on current operations of the raw water treatment plant the aluminium(III)-based coagulation is the most cost efficient. Given a relative costing of 1.00 for the aluminium(III) coagulation, the iron(III) chloride-based coagulation would be 2.67 times more expensive and the equimolar binary mixed aluminium(III)/iron(III) system would be 1.84 times the cost of aluminium(III) coagulation.

Ce travail a pour objectif la mise en place d'un procédé de phytostabilisation sur un ancien site industriel, la Vieille Usine d'Auzon (43, France). La caractérisation pédochimique du site atelier a révélé une pollution polymétallique par l'As, Pb, Sb, Cd et Cu. L'As, de par sa concentration totale et sa biodisponibilité dans le sol, est considéré comme le polluant le plus présent et le plus toxique. L'étude floristique réalisée sur le site a relevé une flore métallicole dominée par des pseudométallophytes électives telles que Agrostis capillaris, Equisetum arvense, ou les Euphorbiacées. De manière générale, la majorité des espèces présentes sur la friche industrielle a accumulé de très faibles quantités de polluants (As, Pb) dans ces parties aériennes. Dans un deuxième temps, les travaux ont porté sur les effets induits par les ETM au niveau physiologique et biochimique chez des modèles végétaux, Agrostis capillaris, Solanum nigrum, Vicia faba et Cannabis sativa. Ces données ont mis en évidence la sensibilité de V. faba et la tolérance de S. nigrum à la pollution aux ETM, un maintien de l'activité physiologique mais un ralentissement de la croissance de C. sativa sur sol pollué et une tolérance adaptative d'A. capillaris à la pollution du sol. Par ailleurs, une culture en hydroponie de S. nigrum et V. faba en présence d'As inorganique, arsénite et arséniate, à différentes concentrations a permis de mettre en évidence deux effets de l'As. Celui-ci a provoqué une altération de la structure et du fonctionnement des PSII, plus sensibles à l'As(III), et, une inhibition de l'activité oxygénase et carboxylase de la Rubisco, cible privilégiée de l'As(V). Enfin, ces résultats ont été utilisés dans le cadre de l'expérimentation in situ pour la validation d'un procédé de phytostabilisation sur la friche industrielle d'Auzon. Les effets de la combinaison d'une association d'espèces prairiales et d'un amendement de grenaille de fer zérovalent ou/et de compost ont pu être caractérisés. L'ajout de grenaille de fer au sol complété par un apport de compost a accentué la réduction de la disponibilité de l'As et dans une moindre mesure de Sb. De plus, il a permis d'enrichir le sol en élément minéraux et organiques et a ainsi facilité l'implantation d'un couvert végétal constitué d'espèces végétales à phénotype d'exclusion. Cette expérience in-situ a donc permis de mettre en avant la faisabilité d'un procédé de phytostabilisation dans la dépollution et la revalorisation de sites industriels. / This work aims to the establishment of a phytostabilization process on an old industrial site, "La Vieille Usine" in Auzon (43, France). The pedochemical characterization revealed a polymetallic pollution by As, Pb, Sb, Cd, Cu. The As, by its total content and its bioavailability, is considered as the most concentrated and toxic. A floristic study noted a metallicolous flora dominated by elective pseudometallophyte species such as Agrostis capillaris, the dominant specie, Equisetum arvense, or Euphorbiaceae. Broadly speaking, the majority of species on the industrial site has accumulated very low amounts of pollutants (As, Pb) in these shoots. To better understand the trace element effects on different plants, Agrostis capillaris, Solanum nigrum, Cannabis sativa and Vicia faba were grown on the Auzon’s soil under controlled conditions. These data highlighted (i) the sensitivity of V. faba and the tolerance of S. nigrum to trace element pollution; (ii) for C. sativa, the maintenance of its physiological activity but a slowdown of its growth; (iii) the adaptative tolerance of A. capillaris to soil pollution. In addition, a hydroponics culture of S. nigrum and V. faba in the presence of different concentrations and different oxidation degrees (arsenite and arsenate) of inorganic As allowed to identify two main effects of As at physiological and biochemical level. First, it alters the structure and function of PSII, which seems more sensitive to As(III), and, secondly, it inhibits the carboxylase and oxygenase activities of Rubisco, the main target of As(V). These data were then used to conduct an in-situ experiment based on a phytostabilization process on the industrial wasteland of Auzon. The effects of the combination of an grassland species association with a zerovalent iron shot and/or compost amendment were characterized. The addition of iron shot on the soil completed with compost decreased the available fraction of As and to a lesser extent Sb. Moreover, the amendments allowed to enrich the soil with mineral and organic elements and to facilitate the establishment of vegetal cover composed by tolerant plants with an exclusion phenotype. This in-situ experience enabled to highlight the feasibility of a phytostabilization method in the depollution of industrial sites as in their enhancement.

Dans les sédiments de rivière à l’aval des drainages miniers acides (DMA), l’arsenic est souvent présent sous les formes As(III) et As(V) associées à des minéraux de type (oxy)hydroxydes de fer et d’aluminium. La structure et la réactivité de ces minéraux qui piègent l’arsenic dans les particules en suspension et dans les sédiments de fond n’ont pour l’instant été que très peu étudiés sur le terrain. Pourtant ces pièges représentent probablement un des facteurs majeurs de contrôle de ce type de contamination dans les eaux à pH proche de la neutralité, impactées par les DMA. Au cours de ce travail de thèse, nous avons étudié la cristallochimie d’une série d’échantillons de ferrihydrites (Fh) riches en aluminium prélevées dans les sédiments de la rivière Amous (Gard, France – pH 6-7), laquelle est affectée par le DMA du site de Carnoulès, contaminé par l’arsenic. Ces Fh ont été caractérisées et comparées à une série de Fh alumineuses synthétiques analogues, qui présentent différents rapports molaires Al/Fe. Des expériences d’adsorption de As(III) et As(V) ont été réalisées sur ces Fh alumineuses et non-alumineuses à pH 6, afin d’évaluer l’influence de l’aluminium sur le piégeage de l’arsenic. Cette étude a combiné l’analyses chimique des solutions avec la caractérisation des solides par Diffraction des Rayons X (DRX), la Microscopie Electronique en Transmission (MET) et la Spectroscopie d’Absorption des Rayons X (XAS). Nous constatons que la ferrihydrite est la phase majoritaire qui se forme au cours de la neutralisation des DMA, et que jusqu'à 25-30 ± 10 mol% Al est substitué à Fe dans la structure de ces Fh. Les Fh alumineuses synthétisées sont moins substituées en aluminium (14 à 20 ± 5 mol% Al). Les résultats obtenus montrent que l’efficacité du piégeage de l’arsenic dépend fortement de la présence d’aluminium dans la ferrihydrite et de l’état d’oxydation de l’arsenic. En effet, à pH 6, l’adsorption de As(III) diminue fortement avec le rapport Al/Fe, tandis que l’adsorption de As(V) augmente avec le rapport Al/Fe. La spectroscopie EXAFS suggère que, à pH6, As(III) forme des complexes de surface bidentate similaires sur les Fh alumineuses ou non-alumineuses, sans évidence de complexation sur les sites aluminols de la surface. En revanche, l’adsorption de As(V), connue par ailleurs pour impliquer des liaisons hydrogène avec la surface de la Fh, apparaît être moins affectée, voire favorisée par la présence d’aluminium. Les données EXAFS montre cependant qu’une fraction de As(V) forme des complexes d’adsorption bidentate sur la Fh alumineuse et sur les Fh non-alumineuses naturelles et synthétiques. Ces résultats constituent une preuve directe du piégeage de l’arsenic par les Fh alumineuses, ce qui souligne l’importance possible du rôle de ces phases minérales dans le piégeage de polluants dans les systèmes naturels ou anthropisés et que la présence d’aluminium peut fortement modifier la réactivité de surface de ce nanomatériau naturel. / In the river system downstream of acid mine drainage (AMD) where the pH of water declined to near neutral, arsenic is usually present as As (III) and As (V) associated to iron and aluminum oxyhydroxydes. Structure and reactivity of these arsenic scavangers have so far been little investigated in the field. However, these traps are probably one of the major factors controlling this type of contamination in water at pH close to neutral, impacted by the DMA.In this thesis, a series of aluminum-rich ferrihydrite (Fh), was removed from the sediments of the river Amous (Gard, France- pH 6-7), which is affected by the AMD Carnoulès contaminated with arsenic. These Fh samples were characterized and compared with a series of Al-bearing Fh, which have different molar ratio of Al/Fe. As(III) and As(V) adsorption experiments were carried out on Al-free ferrihydrite and Al-bearing ferrihydrite at pH 6 to evaluate the influence of aluminum on the arsenic scavenging. This study combined water chemistry analysis with characterization of solide : X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Absorption Spectroscopy of X-rays (XAS).We note that Fh is the predominant phase forming during the neutralization of the AMD, and that up to 25–30 ± 10 mol% Al substitutes for Fe in the structure of Fh naturelle. Synthetic aluminous Fh are found to be less Al-substituted (14–20 ± 5 mol %Al) regardless of the molar ratio Al/Fe we used. The results obtained show that the trapping efficiency of arsenic strongly depends on the presence of aluminum in the ferrihydrite and the oxidation state of the arsenic. Indeed, at pH 6, the adsorption of As (III) greatly decreases with the Al / Fe ratio, whereas the adsorption of As (V) slightly increases with the Al / Fe ratio. The EXAFS analysis suggest that, at pH 6, As(III) forms similar surface complexes (type bidentate) on both Al-free and Al-bearing Fh without evidence of complexation on aluminols sites of the surface. However, the adsorption of As (V), is known to involve hydrogen bonds with the surface of the Fh, appears to be less affected by the presence of aluminum. EXAFS spectroscopy shows however a fraction of As (V) forms adsorption complexes of bidentate on the surface of Al-free and Al-bearing Fh natural and synthetic.These results provide direct evidence of arsenic sequestration by aluminous Fh, underscoring the potential importance of the role of these mineral phases in the trapping of pollutants in natural and engineered systems, and the presence of aluminum can greatly modify the surface reactivity of this natural nanomaterial.

Arsenic is a known carcinogen, but is persistent in the environment, remaining a popular pesticide. It represents a particular hazard to humans when it stays resident in shallow soils and groundwater. This study of contaminant hydrogeology examined conditions at a former golf course in Florida with known arsenic contamination, and included a detailed examination of existing assessment data for the study area, an experimental pumping test with groundwater sampling, examination of sediment cores, and a preliminary geophysical investigation. The primary purpose was to determine what the existing controls are on As mobility. The primary findings were that redox conditions did have an effect on As concentrations. Groundwater in the study area is generally reducing, but during the pumping test was generally oxidizing. No potential As sources were definitively identified, and the most likely source remains anthropogenic, but interactive conditions with Fe, Mn, NO3-N, and S remain nebulous. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

We investigated the transport of dissolved arsenic in groundwater, surface water and the hyporheic zone in a stream-aquifer system influenced by an abandoned arsenopyrite mine. Mine tailing piles consisting of a host of arsenic-bearing minerals including arsenopyrite and scorodite remain adjacent to the stream and represent a continuous source of arsenic. Arsenic loads from the stream, springs, and groundwater were quantified at the study reach on nine dates from January to August 2005 and a mass-balance approach was used to determine hyporheic retention. Arsenic loading from the groundwater was the dominate source of arsenic to the stream, while loads from springs represented a substantial proportion of the total arsenic load during spring. Arsenic loads in surface and groundwater were significantly elevated during summer. Elevated temperatures during summer may lead to increased arsenic loading by increasing dissolution rate of arsenic source minerals and/or increases in microbially-mediated dissolution processes. The hyporheic zone was shown to be retaining arsenic in the upstream-most sub-reach. Retention most likely occurs through the sorption of dissolved arsenic onto hyporheic sediments. In downstream sub-reaches, hyporheic sediments are derived from mine-tailing piles which have high arsenic content. The hyporheic zone in these sub-reaches was shown to be releasing dissolved arsenic. The historic influence of mining activity has resulted in multiple sources of arsenic to the stream which has increased arsenic contamination of the surface waters. / Master of Science

published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

A new analytical method has been developed for the determination of inorganic species or arsenic (arsenite and arsenate); in addition, a new sample preparation method for the determination of these species in atmospheric particulate matter has also been developed. In this procedure, As(III) and As(V) are efficiently separated in a two-step reduction procedure from a solution of HCl. In the first step, a slurry of Zn metal powder is used to reduce As(III) to arsine (AsH₃). Immediately following, NaBH₄ is used to reduce As(V) to AsH₃. The arsine produced during each reduction is detected in an N₂-H₂ air-entrained flame by atomic absorption spectroscopy. In the sample preparation method, sections of quartz or PTFE filters containing atmospheric particulate matter are leached in 10⁻⁴ N HCl for up to 1 hour at 90°C. This procedure quantitatively removes As(III) and As(V) from either filter type. However, small changes in the As(III)/As(V) ratio i.e., oxidation of As(III) were observed when the arsenic species were leached from quartz filters. Therefore, it appears that PTFE would be the preferred filter medium if arsenic speciation is to be performed. When atmospheric particles are present on either filter type, the technique of standard addition is necessary in order to obtain the most accurate results. The combined sample preparation and analysis procedure has a precision of about 10%, 8% and 13% for As(III), As(V) and the As(III)/As(V) ratio, respectively. Atmospheric particulate matter samples collected in Tucson, Arizona, were analyzed for As(III) and As(V) concentrations using the newly developed method. The results of this study indicate that both As(III) and As(V) are present in collected samples of atmospheric particulate matter. Arsenic (V) was observed in all 14 of the samples, while As(III) was measurable in half of the samples. The As(III)/As(V) ratio was determined to be in the range from less than 0.05 to 1. An atmospheric detection limit for either species of 0.09 ng m⁻³ was obtained.

No description available.

This thesis studied the volcanic and geothermal source of arsenic (As) and its fate in shallow ground waters and upon entering the ocean by means of experimental and field measurements combined with geochemical modeling. Arsenic enters the atmosphere and hydrosphere from degassing magmas and during volcanic eruptions. The November 2004 eruption within the Vatnajökull Glacier, Iceland, provided an opportunity to study elemental fluxes from volcanic eruptions into the environment. According to geochemical modeling, lowering of pH due to magma gases during the eruption led to rapid tephra dissolution with corresponding change in flood water chemistry. Geochemical modeling of floodwater/seawater mixing indicated localised decrease in dissolved arsenic and sulphur due to adsorption on the suspended floodwater materials. As the floodwater was diluted the As desorbed and limited effect of the floodwater was predicted after thousand fold dilution. Laboratory experiments were carried out to generate and validate sorption coefficients for arsenite and arsenate in contact with basaltic glass at pH 3 to 10. The mobility of arsenite decreased with increasing pH. The opposite was true for arsenate, being nearly immobile at pH 3 to being highly mobile at pH 10. A 1D reactive transport model constrained by a long time series of field measurements of chemical composition of geothermal effluent fluids from a powerplant was constructed. Thioarsenic species were the dominant form of dissolved As in the waters exiting the power plant but converted to some extent to arsenite and arsenate before feeding into a basaltic lava field. Chloride, moved through the basaltic lava field (4100 m) in less than 10 yrs but arsenate was retarded considerably due to surface reactions and has entered a groundwater well 850 m down the flow path in accordance to prediction by the 1D model, which further predicted a complete breakthrough of arsenate in the year 2100 while arsenite will be retained for about 1000 yrs.