Добірка наукової літератури з теми "Solutions parentérales – Absorption et adsorption"

Banana peel is a low-cost resource that can be used in a wide range of chemical and industrial processes. The novelty of this research is the use of dehydrated and sieved banana peel to remove mercury from water. The main objective of this research is to evaluate the capacity of the banana peel as an adsorbent capable of removing mercury from contaminated water. It has been shown to be an efficient, low-cost, and environmentally friendly process because banana peel is an environmental waste. To determine the ability of the banana peel to adsorb mercury, the following variables were considered: Hg concentration in water (10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 ppb), particle size of the banana peel (100, 150, 200, 250 and 300 microns), quantity of banana peel per 125 ml of solution contaminated with Hg (2 and 5 grams), the contact time was (20, 40 and 60 minutes); it was not necessary to modify the pH of the solutions to obtain high % of mercury removal. The minerals and fatty acids present in the banana peel were also analyzed to improve the interpretation of the adsorption results. A higher adsorption capacity of mercury was perceived with a banana peel sieved at 150 microns; the results are consistent with other research works such as Cd (II) adsorption according to Azarpira et al. [1] where absorption is improved by decreasing the particle size of the filter material. The effectiveness of bioadsorption depends on the initial concentration of mercury ions and the filter material, the particle size of the filter material, the contact time between the mercury ions and the filter material and the pH (although in this project it is not this variable has been intervened). This study demonstrates that the banana peel used as an adsorbent is very efficient and inexpensive for removing mercury from wastewater. It became possible to demonstrate that the amount of Hg adsorbed per unit mass of absorbent increases with increasing initial Hg concentration in contaminated water, as in other metals [1]. The results of this study have confirmed the viability of using banana peel as an effective alternative for removing mercury from mercury-contaminated waters. Future studies will help to evaluate the economic use of this bioadsorbent and the identification of the main active elements it possesses in mercury adsorption. This study will allow a deeper understanding of the mercury absorption process and will verify the potential possibilities of methods to improve the adsorption process.

Background: Over the past decades, significant advances have been made in the field of creating nanobioreagents for solving modern medicine problems (Grebenik et al., JBO, 2013). However, the problem of their low accumulation rate in pathological tissue in vivo experiments still remains. First of all, it is associated with the adsorption of blood proteins on the surface of nanobioreagents and the protein layer formation, which significantly changes the surface properties, which leads to their rapid excretion by the reticuloendothelial system. In particular, it is possible to reduce the blood plasma proteins adsorption and increase the time spent in the circulatory system by forming a coating of proteins. Methods: In situ cryоelectron tomography (Cryo-ET) is the only method that allows the experimental observation of protein structures on the nanoparticle’s surface in their natural functional state. The basic principle of the method is to obtain a series of projections of a vitrified sample thin lamella at different tilt angles related to an incident electron beam. Their further processing leads to obtaining the volumetric information about the structure of the sample. The use of a cryo-focused ion beam (Cryo-FIB) in specimen thinning makes it possible to carry out experiments with thin sections of cellular structures and observe the penetration of nanoparticles into the intracellular environment. Results: Upconverting nanophosphors (AN) were used as a nanoplatform for creating a protein coating. To create a protein coating on the AN surface, they were functionalized using an amphiphilic polymer containing carboxyl groups. Then, conjugation with protein molecules from the class of immunoglobulins was carried out by the method of carbodiimide activation. At each stage of synthesis and modification, AN solutions with different size distribution were vitrified for subsequent tomography. After a series of experiments to study the morphology of nanoparticles, an experiment on their successful absorption by cells of the cancer line A549 was carried out. Conclusion: Within this work, a series of in situ Cryo-ET methods were proposed and applied for structural characterization and visualization of the processes of synthesis, modification, and engulfment of nanoparticles into cellular systems. For the first time in its native form, the engulfment of ANF into the internal environment of the A549 cancer line cells was demonstrated.

High-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) employing a phosphoric acid H3PO4-doped membrane are considered to be promising sustainable electrochemical energy storage. The high-temperature operation has several advantages, such as a higher tolerance to CO poisoning, allowing coupling of HT-PEMFCs with reformers [1-3], as well the possibility for heat and electric energy co-generation [1,2]. However, during operation, phosphorus oxo-acids (e.g.: H3PO3) are generated on the anode. These impurities adsorb on the Pt catalyst [4-6], thus possibly negatively affecting the HT-PEMFCs performance. A detailed understanding of the H3PO3-catalyst (Pt) interaction is hence necessary for further HT-PEMFC optimization. However, besides an investigation of the H3PO3 adsorption behavior on Pt [6,7], literature on the behavior of the H3PO3 in contact with Pt (with/without polarization) is scarce. In this work, the oxidation mechanism of H3PO3 was investigated using a combination of in situ x-ray spectroscopy techniques that directly probe the H3PO3/Pt interface interaction, complemented by ex situ x-ray photoelectron spectroscopy (XPS) and ion-exchange chromatography (IEC). IEC gave insights into the effect of Pt on the stability of deaerated aqueous H3PO3 solutions. XPS was conducted on H3PO3/support structures (including Au and Pt supports) to determine to what extent the support affects the H3PO3 oxidation. Furthermore, in-situ dip and pull near-ambient pressure (NAP-)XPS was conducted to investigate the state of H3PO3 at the H3PO3/Pt interface and in solution bulk. It was observed that at the H3PO3/Pt interface, H3PO3 was chemically oxidized to H3PO4, while in the bulk solution it remains stable, as shown in Figure 1. Moreover, in situ x-ray absorption spectroscopy at the P K-edge was conducted at different concentrations of H3PO3 in aqueous solutions (i.e., different amounts of H2O) in contact with Pt, to determine the role of H2O in the oxidation of H3PO3. A higher degree of oxidation was observed for the less concentrated H3PO3, implying that H2O participates in the oxidation mechanism of H3PO3 to H3PO4. References: [1] Chandan et al., A.. J. Power Sources 2013, 231, 264–278. [2] Asensio, et al. Chem. Soc. Rev. 2010, 39 (8), 3210. [3] Q. Li et al, J. Electrochem. Soc. 2003, 150 (12), A1599. [4] Sugishima et al, J. Electrochem. Soc. 1994, 141 (12), 3332. [5] Doh et al. ChemElectroChem. 2014, 1 (1), 180–186. [6] Prokop et al, Electrochimica Acta 2015, 160, 214–218. [7] Prokop et al, Electrochimica Acta 2016, 212, 465–472. Figure 1

Abstract. Mass accommodation is an essential process for gas–particle partitioning of organic compounds in secondary organic aerosols (SOA). The mass accommodation coefficient is commonly described as the probability of a gas molecule colliding with the surface to enter the particle phase. It is often applied, however, without specifying if and how deep a molecule has to penetrate beneath the surface to be regarded as being incorporated into the condensed phase (adsorption vs. absorption). While this aspect is usually not critical for liquid particles with rapid surface–bulk exchange, it can be important for viscous semi-solid or glassy solid particles to distinguish and resolve the kinetics of accommodation at the surface, transfer across the gas–particle interface, and further transport into the particle bulk. For this purpose, we introduce a novel parameter: an effective mass accommodation coefficient αeff that depends on penetration depth and is a function of surface accommodation coefficient, volatility, bulk diffusivity, and particle-phase reaction rate coefficient. Application of αeff in the traditional Fuchs–Sutugin approximation of mass-transport kinetics at the gas–particle interface yields SOA partitioning results that are consistent with a detailed kinetic multilayer model (kinetic multilayer model of gas–particle interactions in aerosols and clouds, KM-GAP; Shiraiwa et al., 2012) and two-film model solutions (Model for Simulating Aerosol Interactions and Chemistry, MOSAIC; Zaveri et al., 2014) but deviate substantially from earlier modeling approaches not considering the influence of penetration depth and related parameters. For highly viscous or semi-solid particles, we show that the effective mass accommodation coefficient remains similar to the surface accommodation coefficient in the case of low-volatility compounds, whereas it can decrease by several orders of magnitude in the case of semi-volatile compounds. Such effects can explain apparent inconsistencies between earlier studies deriving mass accommodation coefficients from experimental data or from molecular dynamics simulations. Our findings challenge the approach of traditional SOA models using the Fuchs–Sutugin approximation of mass transfer kinetics with a fixed mass accommodation coefficient, regardless of particle phase state and penetration depth. The effective mass accommodation coefficient introduced in this study provides an efficient new way of accounting for the influence of volatility, diffusivity, and particle-phase reactions on SOA partitioning in process models as well as in regional and global air quality models. While kinetic limitations may not be critical for partitioning into liquid SOA particles in the planetary boundary layer (PBL), the effects are likely important for amorphous semi-solid or glassy SOA in the free and upper troposphere (FT–UT) as well as in the PBL at low relative humidity and low temperature.

The puzzling pH dependence of HOR/HER leading to the approximately 2 orders of magnitude loss in platinum group metal (PGM) activity in base has hindered both the practical design of electrochemical devices as well as the fundamental understanding of electrode/electrolyte interfaces.1 Explanations for this effect have ranged from the presence of adsorbates specific to alkaline conditions,2 shifts in the electrode potential of zero free charge (pzfc) and subsequent strengthening of the interfacial electric field,3 the orientation of interfacial water molecules, and changes in the binding energy of reaction intermediates.4–6 Recently, several innovative in situ techniques have been used to probe these theories, ranging from Fourier Transform Infrared Spectroscopy (FTIR) to X-Ray Absorption Spectroscopy (XAS), as well as novel computational studies to isolate the contributions of surface adsorbed hydroxide and water.2–4,7 Additionally, the identification of caffeine as a “double-layer dopant” capable of improving HOR/HER activity 5-fold on Pt(111) has provided the field with a model system with which to systematically test these theories.8 Despite this, an overarching understanding of the mechanism and caffeine’s promoting role is still unclear, and a more rigorous analysis of the electrode surface is necessary. The electrochemical interface is traditionally viewed with a double layer model, with specific electrochemical adsorbates existing in the Inner Helmholtz Plane (IHP), the first layer of non-adsorbates at the Outer Helmholtz Plane (OHP), and water in abundance. One leading theory used to understand the activity loss from acid to alkaline environments is the decrease in surface potential relative to the pzfc in base resulting in stronger electric fields which restrict the approach of reactive intermediates to the IHP/OHP. Caffeine is suspected of reducing the IEF strength through decreasing the pzfc to relevant HOR/HER potentials, creating an acidic like environment. In this work, we challenge this notion by using SEIRAS with CO as a probe molecule to directly measure the interfacial field strength in 0.1 M KOH solutions with the model caffeine system showing HOR/HER enhancement, as well as different concentrations of various organic species with no promoting kinetic impact. FTIR studies using CO as a probe molecule to measure stark tuning rates have long been used to directly measure the interfacial electric field strength, dictated by the majority species in the OHP.9,10 The low ST rate of 22 cm-1V-1 found for all of these species in our experiments, regardless of their impact on HOR/HER kinetics, implies reductions in IEF are not solely responsible for the KOH-caffeine system’s increased activity. Rather, caffeine induces changes to the interfacial water structure as evidenced by differences in water’s ν(O-H) stretching modes, allowing for more facile kinetics, the main parameter responsible for the “apparent pH dependence” of PGM HOR/HER. Durst, J. et al. New insights into the electrochemical hydrogen oxidation and evolution reaction mechanism. Energy Environ. Sci. 7, 2255–2260 (2014). McCrum, I. T. & Koper, M. T. M. The role of adsorbed hydroxide in hydrogen evolution reaction kinetics on modified platinum. Nat. Energy 5, 891–899 (2020). Sarabia, F. J., Sebastián-Pascual, P., Koper, M. T. M., Climent, V. & Feliu, J. M. Effect of the Interfacial Water Structure on the Hydrogen Evolution Reaction on Pt(111) Modified with Different Nickel Hydroxide Coverages in Alkaline Media. ACS Appl. Mater. Interfaces 11, 613–623 (2019). Liu, E. et al. Interfacial water shuffling the intermediates of hydrogen oxidation and evolution reactions in aqueous media. Energy Environ. Sci. 13, 3064–3074 (2020). Yang, X., Nash, J., Oliveira, N. J., Yan, Y. & Xu, B. Understanding the pH Dependence of Underpotential Deposited Hydrogen on Platinum. Angew. Chemie - Int. Ed. 58, 17718–17723 (2019). Rebollar, L. et al. On the relationship between potential of zero charge and solvent dynamics in the reversible hydrogen electrode. J. Catal. 398, 161–170 (2021). Cheng, T., Wang, L., Merinov, B. V. & Goddard, W. A. Explanation of Dramatic pH-Dependence of Hydrogen Binding on Noble Metal Electrode: Greatly Weakened Water Adsorption at High pH. J. Am. Chem. Soc. 140, 7787–7790 (2018). Intikhab, S. et al. Caffeinated Interfaces Enhance Alkaline Hydrogen Electrocatalysis. ACS Catal. 10, 6798–6802 (2020). Lambert, D. K. Vibrational Stark effect of CO on Ni(100), and CO in the aqueous double layer: Experiment, theory, and models. J. Chem. Phys. 89, 3847–3860 (1988). Anderson, M. R., Blackwood, D. & Pons, S. The behavior of the infrared spectrum of carbon monoxide adsorbed at platinum electrodes from non-aqueous solvents. J. Electroanal. Chem. 256, 387–395 (1988). Figure 1

The demanding multi-electron transfer process renders the oxygen evolution reaction (OER) a bottleneck for achieving efficient clean hydrogen generation via water electrolysis.[1] Over the past decades, two main categories of catalysts, namely, homogeneous molecular and heterogeneous catalysts, have been implemented for the OER. However, due to the sluggish reaction kinetics and the aggressive reaction media of the OER, the structural integrity of both homogeneous molecular and heterogeneous catalysts faces the dramatic challenges. This calls for a thorough understanding and close monitoring of OER catalysts under their operando reaction conditions. Over the last years, we have been combining a variety of in situ/operando spectroscopy approaches with computational studies toward the comprehensive understanding of our designed catalysts at the atomic level. With this information in hand, we established a full identification of catalytically active species and sites for several systems, some of which are discussed here. First, inspired by nature’s {Mn4CaOx} OER complexes, we recently reported on the design of a tetramer Cu-bipyridyl complex for the OER.[2] Structural characterizations demonstrated a new defect-cubane structure of our designed complex, [Cu4(pyalk)4(OAc)4](ClO4)(HNEt3). We found that this Cu-bipyridyl complex can further undergo structural transformations into two unique complexes under different solution conditions, namely Cu-dimer and Cu-monomers, as revealed by in situ UV-vis and ERP characterizations as well as electrospray ionization mass spectrometry. Specifically, the Cu-monomers can be only formed in presence of carbonate buffer (pH 10.5). Otherwise, the structural transformation into a Cu-dimer complex [Cu2(pyalk)2(OAc)2(H2O)] is dominant under solution conditions. Furthermore, electrochemical characterizations revealed an overpotential of 960 mV to reach a current density of 0.1 mA/cm2 of our designed Cu-dimer catalysts, which is comparable with significant Cu-based OER electrocatalysts. To gain in-depth insights into their conversion processes, postcatalytic characterizations of Cu-based molecular catalysts were carried out based on X-ray photoelectron/absorption (XAS/XPS) spectroscopy appraoches. The results showed that nanosized Cu-oxide-based species were formed in situ in Cu-based molecular catalysts after the OER. Our study highlights the crucial role of the structural integrity of molecular catalysts in solutions for their efficient design. In parallel, we explored the structural transformations of heterogeneous electrocatalysts during the OER. As a typical example, we developed a cost-effective and high-performance NiFe-based coordination polymer (referred to as NiFe-CP) as OER electrocatalyst, which is being investigated as the best-known bimetallic combination for the OER.[3] A central element of our study is the monitoring of true catalytically active species. Results from spectroscopic characterizations revealed a kinetic restructuring of NiFe-CPs into NiFe (oxy)hydroxides during the OER. To further improve the OER activity, we introduced a facile NaBH4-assisted reduction strategy to prepare low-crystalline reduced NiFe-CP (denoted as R-NiFe-CP) OER electrocatalysts with rich structural deficiencies. These catalysts can maintain a very low overpotential of 225 mV at 10 mA/cm2 for over 120 h without any performance decline, outperforming many recent reported bimetallic OER electrocatalysts. As revealed by XAS characterizations and density functional theory (DFT) calculations, engineering of structural deficiencies not only tunes the local electronic structure but also optimizes the rate-determining step towards facilitated OH- adsorption. Noteworthy, the true OER active sites of R-NiFe-CPs originate from the in situ reconstructed Ni-O-Fe motifs. However, fundamental questions, as to (a) the role of engineered structural deficiencies in the generation of active species and (b) facilitating the formation of catalytically active dual oxygen-bridged moieties, need to be answered. Combination of time-resolved operando XAS monitoring and DFT calculations enables the tracking and understanding of the kinetic changes of active species and sites under the operando reaction conditions. We found that the OER of R-NiFe-CPs relies on the in situ formation of crucial high-valent NiIV-O-FeIVO moieties.[4] Furthermore, an anionic engineering strategy through heteroatom sulfur incorporation was carried out to obtain S-R-NiFe-CP showing faster OER kinetics. Importantly, engineered sulfur content promotes the generation of catalytically active S-NiIVO-FeIVO motifs prior to the OER. This offers a lower onset potential to trigger the OER of S-R-NiFe-CPs compared to sulfur-free R-NiFe-CPs. Moreover, our results also suggest a dual-site mechanism pathway of S-R-NiFe-CPs during the OER, in which the O-O bond formed atop the S-NiIVO-FeIVO moieties. Such an anionic modulation strategy for promoting the formation of catalytically active structural moieties and for optimizing the OER kinetics opens an avenue to optimize a wide range of heterogeneous catalysts for the OER. [1] Zhao, Y. et al. Chem. Rev. 2023 , doi.org/10.1021/acs.chemrev.2c00515. [2] Adiyeri Saseendran, D. P. et al. Chem. Comm. 2023, In Revision. [3] Zhao, Y. et al. Adv. Energy Mater. 2020, 10, 2002228. [4] Zhao, Y. et al. ACS Nano 2022, 16, 15318-15327.

Introduction Nanoparticles of Pt as well as Pt-based alloys are widely used as cathode catalyst materials for proton exchange membrane fuel cells (PEMFC). However, electrochemical stability of the materials is rather low under practical operating conditions of PEMFC cathode, resulting in severe deactivation of oxygen reduction reaction (ORR). Therefore, further material’s developments are required for next-generation PEMFC cathode catalysts, i.e., more enhanced ORR durability with low platinum group metal (PGM) usage. High entropy alloys (HEAs), defined as single phase solid solutions of five or more elements in equal composition ratios, are known as thermodynamically stable, in comparison to conventional binary alloys. Furthermore, complex atomic-level local structures bring about unique electronic as well as (electro-)chemical properties that originating from lattice strains induced by specific local structures and/or so-called sluggish diffusion of the constituent elements. [1] However, to our best knowledge, no study has been made for ORR properties of Pt alloying with non-PGM Cantor alloy (fcc structure HEA with equi-atomic ratio of Cr-Mn-Fe-Co-Ni [2]) elements in strong acid condition. In this study, we synthesized lattice stacking structures of Pt/HEA(hkl) (hkl = (111), (110), (100)) through arc-plasma deposition (APD) of the Cantor alloy layer on Pt(hkl) substrate surfaces, followed by deposition of the surface Pt layer in ~10-7 Pa. Then, we performed cross-sectional STEM-EDS observations for Pt/HEA/Pt(hkl) stacking structures with atomic-level resolution and evaluated the ORR properties (initial activity and structural stability). Experimental An APD target of Cr-Mn-Fe-Co-Ni (Cantor alloy) was fabricated by sintering of equal quantity corresponding elements. 10 ML(monolayer)-thick (1 ML = ca. 0.3 nm) Cantor alloy layer (as HEA) was vacuum-deposited by APD on surface cleaned Pt(hkl) substrate surfaces at 300 K, and subsequently annealed in vacuum at 773 K for 30 minutes. Then, 4ML-thick Pt layer was deposited on the pre-deposited Cantor alloy layer at 300 K and annealed at 623 K. The samples thus prepared are designated as Pt/HEA/Pt(hkl). The atomic-level micro-structures and chemical bonding states of Pt/HEA/Pt(hkl) surfaces were characterized by cross-sectional STEM-EDS, RHEED, XPS etc. CV and LSV with the RDE method were conducted in N2-purged and O2-saturated 0.1 M HClO4. ORR activity was evaluated from j k values at 0.9 V vs. RHE by using Koutecky-Levich equation and structural stability (ORR durability) was discussed based upon activity transitions during applying the potential cycles (PCs) of 0.6(3s)‐1.0(3s) V vs. RHE in O2 saturated 0.1 M HClO4 at room temperature. Results and Discussion Atomically-resolved, cross-sectional HAADF-STEM images for Pt/HEA/Pt(hkl) (a) and EDS line profiles of elemental distributions at corresponding yellow arrows (b) are presented in Figure 1. As clearly shown in (a), irrespective of the Pt surface indices, (hkl), HEA (Cantor alloy) and surface Pt layers are epitaxially grown on the substrates. By contrast, elemental distributions in each surface normal (b) seriously depend on the substrate Pt lattice indices. Notably, severe thermal diffusion of the constituent elements including Pt is confirmed by (a) and (b) for both Pt/HEA/Pt(110) and (100). Figure 2 summarizes electrochemical results. 4ML-thick-Pt/10ML-thick-Co/Pt(hkl) that prepared under the same preparation condition of Pt/HEA/Pt(hkl), and clean Pt(hkl) (light blue and gray, respectively) are also shown as references. As shown in the figure, the Pt/HEA and Pt/Co fabricated on Pt(111) substrate (top) show quite similar CV characteristics (shrink in hydrogen adsorption charges (0 – 0.3 V) and higher potential shifts in oxygen-related species adsorption (0.6 – 1.0 V)), in comparison to clean Pt(111), and almost the same initial ORR activity. Meanwhile, the Pt/HEA fabricated on Pt(110) and (100) substrates show more reduced hydrogen absorption charges, compared with corresponding Pt/Co samples. Particularly, distinctive redox features for clean Pt(110) at 0.12 V and for Pt(100) at 0.35 V are absent for corresponding CVs, suggesting specific topmost surface atomic-structures might be formed in the electrolyte, that probably resulting from significant electronic interactions between surface Pt and HEA constituent elements (Cr, Mn, Fe, Co, Ni) and/or local strain of the surface Pt layer induced by distorted Pt-HEA lattices located nearby. One might notice that Pt/HEA/Pt(110) reveals remarkable ORR activity enhancement compared with corresponding Pt/Co/Pt(110), while the activities for Pt/HEA and corresponding Pt/Co surfaces fabricated on Pt(100) are almost the same value. At the meeting, correlations between surface atomic-level micro-structures of Pt/HEA/Pt(hkl) and ORR properties will be discussed in detail. Acknowledgement This study was supported by new energy and industrial technology development organization (NEDO) of Japan and JST SPRING, Grant Number JPMJJSP2114. Reference [1] J. Yeh, JOM, 65, 1759 (2013). [2] B. Cantor et al., Mater. Sci. Eng. A, 375, 213 (2004). Figure 1

Les matériaux polymères sont très utilisés dans le domaine de la perfusion mais sont connus pour interagir avec certains médicaments en contact. Les interactions contenant-contenu entre un dispositif médical de perfusion et un médicament sont susceptibles d’altérer la prise en charge thérapeutique du patient par relargage d’additifs ou perte de médicament par sorption. Ces interactions sont variables, elles dépendent de la composition du dispositif, et de celle du médicament (principe actif, excipients). L’étude a été faite sur les interactions entre des tubes de perfusion et des médicaments en solution aqueuse. Deux principes actifs (PA) présentant des lipophilies différentes ont été étudiés : le Paracétamol et le Diazépam. Différents polymères ont été sélectionnés pour les tubes de perfusion : le Polyéthylène (PE) et le Polychlorure de vinyle (PVC). Les tubes en PVC sont plastifiés pour obtenir une bonne flexibilité. Trois plastifiants ont été retenus : le DINCH, le DEHT (DEHTP) et le TOTM (TEHTM). Les solutions médicamenteuses ont été mises en contact avec les différents tubes de perfusion. La chromatographie en phase liquide a permis de quantifier les PA et les plastifiants présents dans le solution après contact avec une tubulure en perfusion. Cette étude expérimentale a rendu possible le suivi de l’évolution de la concentration en principe actif et en plastifiants dans la solution en faisant varier la durer de contact. La simulation moléculaire a permis d’améliorer la compréhension des phénomènes de sorption et de migration des plastifiants au niveau des interactions moléculaires et des spécificités de l’interface à l’échelle moléculaire. Des caractérisations énergétiques ont permis d’améliorer la compréhension des interactions qui conduisent à l’adsorption du médicament, et au relargage des plastifiants. La méthode du potentiel de force moyenne (PMF) a été utilisée pour calculer l’énergie libre liée à l’adsorption du principe actif.L’étude a démarré sur les phénomènes de sorption avec l’étude des interactions entre les principes actifs et les surfaces en PE et PVC pur. Une deuxième étape a pris en compte les interactions avec des surfaces plus complexes, les PVC plastifiés. Enfin, la dernière partie a porté sur l’étude du relargage des plastifiants dans la solution au contact avec les tubulures, et sur l’influence de la solution sur l’adsorption du principe actif.Pour conclure, les résultats expérimentaux ont permis de valider les méthodologies de simulation et les modèles moléculaires, et la simulation a apporté une vision moléculaire des phénomènes d’adsorption des principes actifs et de migration des plastifiants. La combinaison de ces deux approches est une plus-value considérable pour concevoir de nouveaux matériaux et/ou rationaliser sur les expériences
Polymeric materials are widely used for the infusion of medications, but they are known to interact with certain drugs. Container-content interactions between a medical infusion device and a drug are likely to alter the therapeutic care of the patient through the release of additives or loss of drug through sorption. These interactions are variable, and depend on the composition of both the device and the drug (active ingredient, excipients).The study focuses on the interactions between infusion tubes and drugs diluted in water-based solution. Two active pharmaceutical ingredients (API) with different lipophilicity were studied: paracetamol and diazepam. Different polymers are studied for infusion tubings: polyethylene (PE) and polyvinyl chloride (PVC). PVC tubings are plasticized with plasticizers to obtain the needed flexibility and ease of use. In this work three plasticizers were selected: DINCH, DEHT (DEHTP) and TOTM (TEHTM).Drug solutions were put into contact with the various infusion tubes. Liquid chromatography was used to quantify the API and plasticizers in the solutions after contact with the infusion tubings. This experimental study made it possible to follow changes in the concentration of the API and plasticizers in the solution, by varying the contact time.Molecular simulation allowed better understanding of the sorption phenomena and of the plasticizers’ migration at molecular and interfacial level, whilst considering the interactions and the miscroscopic specificities. Energy characterizations were used to gain an improved understanding of the interactions leading to drug adsorption and plasticizer release. The Potential of Mean Force (PMF) method was used to calculate the free energy associated with adsorption of the API.Initially, the study focused on sorption phenomena, more specifically on interactions between API and PE and pure PVC surfaces. This first step enabled us to study the interactions with more complex surfaces, such as plasticized PVCs. Finally, the last part studied the release of the plasticizers into the solution in contact with the tubings, as well as the influence of the composition of the solutions on the adsorption of the APIs.In conclusion, the experimental results validated the simulation methodologies, whilst the simulation results provided a molecular vision of the API adsorption and plasticizer migration phenomena. The combination of these two approaches offers considerable added value for the design of new materials and/or the rationalization of experiments

Cette thèse traite de l'amélioration de la modélisation d'un procédé de désacidification du gaz naturel par des solutions aqueuses d'alcanolamines, principalement la DiEthanolAmine (DEA) et la MethyDiEthanolAmine (MDEA). Après une étude bibliographique sur les mécanismes réactionnels entre le CO2, l'H2S et les amines primaires et secondaires et sur les modèles de transfert de chaleur et de matière, un modèle d'absorption réactive basé sur la théorie du double film a été développé. Ce modèle utilise l'équation de Nernst-Planck dans le film liquide et les équations de Stefan-Maxwell dans le film gaz. Le traitement des réactions chimiques dans la phase liquide est différencié suivant leur caractère lent ou instantané. Après validation du modèle de transfert par comparaison avec des cas simples de la littérature, ce modèle est introduit au sein d'un simulateur de colonne existant. Le nouveau code de calcul ainsi développé permet de représenter avec succès les cas de colonnes d'absorption industrielles en terme de flux transférés et de facteur d'accélération.

Le but de cette thèse est l'étude des nouveaux couples et des nouvelles structures pour frigopompes et thermofrigopompes. Comme nouveaux couples, nous proposons d'utiliser des couples formes de deux hydrocarbures saturés de volatilités différentes. Ces couples présentent de nombreux avantages: ils forment des solutions idéales: les propriétés thermodynamiques des mélanges sont connues, le rapport des chaleurs latentes d'évaporation du compose léger et du composé lourd est grand, ce qui entraine une haute performance, ils ne provoquent aucun risque de corrosion ni de toxicité. Comme nouvelle structure, nous proposons une cellule de vaporisation-condensation a tubes verticaux de géométrie modifiée, notamment par des ailettes spiralées, sur lesquelles ruisselle le film liquide en cours d'interaction avec le gaz. Cette structure présente une forte augmentation des transferts de chaleur et de matière, par comparaison avec un tube a paroi lisse

L'évaporation osmotique est une nouvelle opération membranaire dont le but est la concentration de solutions aqueuses à température ambiante et à pression atmosphérique. Le liquide à concentrer (phase d'alimentation) est séparé d'une solution salée très concentrée (phase réceptrice) par l'intermédiaire d'une fine membrane microporeuse hydrophobe. Le moteur du transfert de vapeur d'eau de la phase d'alimentation vers la phase réceptrice est un gradient de pression de vapeur d'eau dû à la différence de pression osmotique entre les deux liquides de part et d'autre de la membrane. Une synthèse bibliographique permet de situer l'évaporation osmotique par rapport aux autres contacteurs à membrane et notamment, par rapport à la distillation membranaire. L'étude théorique montre que dans des conditions normales d'utilisation, le flux de vapeur s'exprimera de façon différente selon la valeur du rapport du libre parcours moyen des molécules à la dimension de pore : selon les cas, la dimension de pore influera ou non sur le flux de vapeur transférée. Par la suite, une étude du procédé en cellule de diffusion a été menée. Les influences sur le flux de la pression osmotique de la phase réceptrice, des vitesses d'agitation des solutions, de la température ainsi que celles de l'épaisseur et de la dimension des pores de la membrane ont été évaluées. Les résultats de cette étude paramétrique ont ensuite été utilisés pour vérifier la validité du modèle de transport, évaluer les résistances au transport dues à la membrane et à la couche limite de concentration dans la phase réceptrice et enfin pour modéliser le procédé en cellule agitée (régime non laminaire) par l'établissement d'une expression reliant les trois nombres adimensionnels Reynolds, Schmidt et Sherwood. L'étude en cellule agitée a été complétée par une évaluation du rôle joué par la présence d'air dans les pores et par une application à la concentration de solutions à fortes teneurs en glucose. La dernière partie du travail concerne des essais pilotes sur du jus de pomme. Elle a montré la possibilité de concentrer ce jus de fruit jusqu'à 630 g/I. Dans la perspective d'une application industrielle, un schéma type d'installation combinant osmose inverse et évaporation osmotique a été proposé et les consommations énergétiques estimées.

Les problèmes de pollution des sols par des éléments traces métalliques étant de plus en plus nombreux, il est important de comprendre le comportement des métaux au sein de ces sols et d'appréhender leur transfert. Cette compréhension passe par une description des interactions entre ces éléments et les principaux compartiments réactifs des sols (matière organique, oxydes de fer et de manganèse et argiles). L'objectif de ce travail était de développer une approche basée sur la combinaison de plusieurs modèles pour l'étude de la Spéciation des éléments traces métalliques dans le sol et la solution du sol. Les modèles utilisés pour décrire les interactions des métaux avec les principales phases reactives du sol sont CD-MUSIC (oxydes de fer amorphes et cristallisés), NICA-Donnan (matière organique et oxydes de manganèse) et un modèle d'échange cationique basé sur. La convention de Gaines Thomas (argiles). Ce travail implique dans un premier temps la définition de constantes permettant de décrire les interactions des métaux étudiés (Cd, Cu, Pb et Zn) avec les oxydes de fer et de manganèse, une partie de ces informations n'étant pas disponible dans la littérature. La combinaison de ces modèles a été appliquée à deux sites naturels. Le premier est situé dans le Nord de la France à proximité d'une usine pyrométallurgique, il est contaminé en métaux par dépôts atmosphériques et le deuxième, situé en Bretagne est contaminé en cuivre et en zinc par épandage intensif de lisier porcin. Les résultats de la modélisation ont été comparés avec des résultats analytiques (extractions chimiques sélectives, utilisation d'une membrane échangeuse de cations et études EXAFS réalisées au cours de travaux antérieurs), afin de valider l'approche utilisée
Nowadays, environmental problems related to soil pollution with heavy metals are numerous, therefore, it is important to understand metals behavior in soils and to appreciate their transfer. The fate of the metals in the environment is closely related to their interactions with the major reactive soil compartments (organic matter, iron and manganese oxides, clays). The objective of this work is to develop an approach based on the combination of several model to study metal ion speciation in the soil and the soil solution. Models used to describe the interactions of metals with the main reactive phases in the soil are CD-MUSIC (amorphous and crystallized iron oxides), NICA-Donnarf (organic matter and manganese oxides), cationic ion exchange model (clays). First, this work implies the definition of generic parameters to describe the interactions of the studied metals (Cd, Cu, Pb and Zn) with iron and manganese oxides, a part of this information is missing in the literature. Then, after the validation of the approach by comparison with analytical results, this multi-surface model is applied to two contaminated soils located in the North of France (atmospheric deposits) and in Brittany (intensive pig manure applications)

L'etude des equilibres mineraux - solution dans le domaine non sature des sols necessite de considerer l'etat particulier de l'eau. L'eau liquide liee, en conditions capillaires, est soumise a une pression generalement negative, en tout cas inferieure a celle de l'atmosphere. Une methode de calcul de toutes les proprietes thermodynamiques de l'eau, fondee sur cette realite physique, est proposee et discutee au chapitre 1, a partir de la regression des donnees etablies a pression positive. Le chapitre 2 presente le calcul des proprietes thermodynamiques de la plupart des polymorphes de la glace. La notion d'<<<>ice-like water<>>> peut alors etre clairement definie, au chapitre 3, et appliquee a l'eau de constitution des hydrates et des hydroxydes. . . .

La pollution de l'eau résultant de la présence excessive de nutriments azotés issus de pratiques agricoles et des activités humaines telles que la décharge des eaux usées domestiques et industrielles est devenue un problème environnemental majeur. L’objectif principal de cette étude est l’optimisation de la formulation de nouveaux adsorbants pour l’élimination des ions ammonium contenus dans les effluents d’origine agricole. À cet effet, deux matériaux mésoporeux fonctionnalisés avec des groupements arène et propyl-sulfonique acides par cocondensation et greffage post-synthèse d’une part et un nouvel adsorbant contenant un groupement benzénique ponté d’autre part ont été synthétisé. Ils ont été caractérisés et testés en modes discontinu et en continu. Les adsorbants arène et propylsulfonique acides avec un rapport molaire organosilane/silice de 20% affichent une capacité maximale d'adsorption d'environ 25 mg NH4+/g à la température la plus basse étudiée (5°C). Pour une concentration initiale d'ammonium donnée, l'efficacité d'élimination (W) augmente avec l'augmentation de la charge en adsorbant. La capacité d'adsorption s’est améliorée avec l'augmentation du rapport molaire organosilane/silice pour atteindre 42 mg de NH4+/g avec un rapport de 40 % à 25° C. Les données d'équilibre des deux adsorbants suivent le modèle de Langmuir et le modèle cinétique de pseudo second ordre est celui qui décrit le mieux leur comportement cinétique. Les valeurs négatives de l'enthalpie (ΔH°) et de l'entropie (ΔS0) obtenues indiquent que la réaction est exothermique et qu’il y a baisse de l'arrangement aléatoire de l'adsorbat à l'interface solide/liquide, respectivement. Enfin, les adsorbants sont facilement régénérés et ont maintenu leurs capacités d'adsorption après cinq cycles consécutifs d’adsorption-désorption. L’étude en continu a été réalisée avec l’adsorbant arène sulfonique synthétisé par greffage. Les résultats obtenus montrent que le temps de survenue des courbes de percée diminue avec l'augmentation du débit et de la concentration initiale, mais augmente avec l'augmentation de la hauteur du lit. Les modèles de Thomas et Yoon-Nelson ont permis une bonne prédiction des courbes de percée expérimentales. Enfin, les courbes de percée n'ont pas été modifiées après trois cycles consécutifs d’adsorption-désorption. Avec l’adsorbant contenant le groupement benzénique ponté, des capacités comprises entre 34 et 40 mg NH4+/g ont été obtenues.
Water pollution resulting from the excessive presence of nitrogen nutrients arising from agricultural practices and human activities such as the discharge of domestic and industrial wastewater has become a major environmental problem. The main objective of this study is to optimize the formulation of new adsorbents for the removal of ammonium ions contained in agricultural runoff. For this purpose, two mesoporous materials functionalized with arene and propyl sulfonic acid groups by cocondensation and post-synthesis grafting on the one hand and a novel adsorbent containing a bridged benzene moiety on the other hand were synthesized. They have been characterized and tested in batch and continuous modes. Arene and propylsulfonic acid adsorbents with an organosilane/silica molar ratio of 20% show a maximum adsorption capacity of about 25 mg NH4+/g at the lowest temperature studied (5° C). For a given initial ammonium concentration, the removal efficiency (W) increased with increasing adsorbent loading. The adsorption capacity was improved by increasing the molar organosilane silica ratio to reach 42 mg NH4+/g with a ratio of 40% at 25 ° C. The equilibrium data of both adsorbents followed the Langmuir model and the kinetic pseudo second order model is the one that best describes their kinetic behavior. Negative values of the enthalpy (ΔH0) and entropy (ΔS0) obtained indicate that the reaction is exothermic and that there is downward of the random arrangement of the adsorbate at the solid/liquid interface, respectively. Finally, the adsorbents are regenerated easily and maintained their adsorption capacity after five consecutive cycles of adsorption-desorption. The continuous study was conducted with the arene sulfonic acid adsorbent synthesized by grafting. The results obtained show that the time of occurrence of breakthrough curves decreases with increasing flow rate and initial ammonium concentration, but increases with increased bed height. Thomas and Yoon-Nelson models allowed a good prediction of experimental breakthrough curves. Finally, the breakthrough curves were not changed significantly after three consecutive cycles of adsorption-desorption. With the adsorbent containing the bridged benzene group, adsorption capacities between 34 and 40 mg NH4+/g were obtained.

De nombreux travaux ont démontré que l'utilisation des SHA réduit le taux d'infections nosocomiales. Cependant, la qualité de friction avec SHA a été rarement évaluée. Un des objectifs de ce travail est d'évaluer la qualité de friction et la tolérance cutanée aux SHA sur le long terme. Lors d'une utilisation intensive en milieu hospitalier, les conséquences du passage systémique de l'éthanol par pénétration cutanée ou par inhalation restent encore un sujet de débat. Le second objectif est d'évaluer l'exposition aux SHA, dans des conditions expérimentales, et dans les conditions réelles de travail en milieu hospitalier. Ce travail a démontré une baisse de la qualité de friction à trois ans de la formation. L'utilisation des SHA augmente l'hydratation de la peau. Les SHA sont tolérées par les soignants. Les mesures réalisées en laboratoire, ont montré que l'exposition a l'éthanol des SHA est de brève durée mais à des concentrations importantes. La quantification d'éthanol dans l'air ambiant d'une chambre de patient, durant 8 heures d'utilisation intensive de SHA, a montré que le patient et le soignant sont exposés à la même quantité de vapeurs d'éthanol, cependant cette quantité est inférieure à la valeur limite d'exposition professionnelle française. L'étude réalisée au CHU, a montré que l'exposition des soignants aux SHA à court terme, ne conduit pas à une absorption décelable de l'éthanol et de ses métabolites. La concentration d'éthanol dans l'air inhalé, reste inférieure aux valeurs limites réglementaires françaises. L'ensemble de ce projet se déroule sur 10 ans, il permettra de vérifier les possibles effets secondaires liés à l'utilisation des SHA sur le long terme
Previous studies have shown that the use of Acohol-Based Hand Rubs (ABHRs) has been associated with reduced rates of nosocomial infections. However, the quality of hand rubbing with ABHRs has rarely been evaluated. The first aim of this work is to evaluate the quality of hand rubbing and skin tolerance to ABHRs in the long term. The consequences of systemic passage of alcohol by inhalation or dermal absorption during intensive use of these products in hospitals remain a subject of debate. The second aim of our work is to assess the exposure of Healthcare Workers (HCWs) to ABHRs, under experimental conditions in the laboratory and under a real situation of work shift in hospital. Our study demonstrated a decrease in the quality of hand rubbing. The use of these products increases skin hydration. ABHRs are well tolerated by HCWs and do not dry the skin.The measurements made in the laboratory showed that exposure to ethanol during ABHRs handling is of short duration but at high concentrations. The quantification of ethanol in ambient air of a patient room for eight hours of ABHRS intensive use showed that the patient and HCW are exposed to the same amount of ethanol vapours. However this amount remains far inferior to the French guidelines for professional exposure limits to ethanol over 8 hours. The hospital study showed that exposure of HCWs to ABHR at short term does not lead to detectable absorption of ethanol and its metabolites. Quantification of ethanol vapour in the inhaled air remains well below the levels known to be toxic in humans. The whole project takes place over 10 years; it will verify the potential side effects associated with the ABHRs use for a long-term

Le travail presente dans ce memoire concerne une etude du devenir d'un herbicide du mais, l'atrazine en condition de plein-champ: bilan et modes de dissipation. Des experimentations de laboratoire mettant en jeu des methodes diverses (suivi de l'atrazine #1#4c, couches minces et colonnes de terre, lysimetre non remanie) permettent d'etayer les resultats obtenus sur la parcelle experimentale du site observatoire des pollutions diffuses du lycee agricole de la cote saint andre (isere, france) ou a ete suivie pendant 3 ans la composition en herbicide et metabolites du sol sur 1 metre de profondeur et celle de l'eau interstitielle prelevee par bougies filtrantes. La matiere active (1 kg/ha) apportee annuellement fin avril se dissipe selon cinq voies d'importances tres inegales: volatilisation (15%), absorption par la culture (10%), adsorption sur le complexe argilo-humique et metabolisation (40-50%), entrainement vers les eaux profondes (30-40%). Dans la situation etudiee, les deux voies principales sont la metabolisation par la microflore du sol et l'entrainement lors des episodes pluvieux precoces. Apres un an de culture, la teneur en atrazine et derives au sein du premier metre de sol est voisine de 400 g/ha ce qui indique que l'evacuation de la matiere active n'est pas complete. Notre etude de terrain completee par une experimentation de laboratoire, conduit a mettre en evidence la possibilite de pertes precoces importantes de matiere active durant les deux premiers mois de culture. Trois concepts importants relatifs a l'efficacite d'un herbicide de prelevee emergent de notre etude: la concentration critique dans l'eau du sol, la duree critique durant laquelle cette concentration doit etre maintenue pour assurer l'effet herbicide, la profondeur critique qui represente la couche de sol dans laquelle doit jouer l'effet herbicide. Pour l'atrazine en culture de mais, dans nos conditions, ces criteres ont ete mesures: concentration critique: entre 50 et 200 micromoles ; duree critique: deux mois ; profondeur critique: 10 cm. Avec 1 kg/ha d'atrazine sous forme de suspension concentree, les trois criteres d'efficacite sont remplis malgre d'importantes pertes par drainage lors des episodes pluvieux precoces. Des modifications de formulation ayant pour consequence un relargage progressif devrait permettre l'economie d'une part importante de matiere active. La derniere partie de ce travail concerne une approche de mise en place de solutions alternatives de traitements herbicides en culture de mais

Research studies on the adsorption kinetics are conducted in order to determine the absorption time of heavy metals on coffee grounds from liquid. The models of adsorption kinetics and adsorption diffusion are based on mathe-matical models (Cho et al. 2005). The adsorption kinetics can provide information on the mechanisms occurring be-tween adsorbates and adsorbents and give an understanding of the adsorption process. In the mathematical modelling of processes, Lagergren’s pseudo-first- and pseudo-second-order kinetics and the intra-particle diffusion models are usually applied. The mathematical modelling has shown that the kinetics of the adsorption process of heavy metals (copper (Cu) and lead (Pb)) is more appropriately described by the Lagergren’s pseudo-second-order kinetic model. The kinetic constants (k2Cu = 0.117; k2Pb = 0,037 min−1) and the sorption process speed (k2qeCu = 0.0058–0.4975; k2qePb = 0.021–0.1661 mg/g per min) were calculated. After completing the mathematical modelling it was calculated that the Langmuir isotherm better reflects the sorption processes of copper (Cu) (R2 = 0.950), whilst the Freundlich isotherm – the sorption processes of lead (Pb) (R2 = 0.925). The difference between the mathematically modelled and experimen-tally obtained sorption capacities for removal of heavy metals on coffee grounds from aqueous solutions is 0.059–0.164 mg/l for copper and 0.004–0.285 mg/l for lead. Residual concentrations of metals in a solution showed difference of 1.01 and 0.96 mg/l, respectively.