Synthèse de l’analcime et caractérisation par DRX, MEB et MET

Des investigations préliminaires ont permis de mettre au point une voie assez originale de synthèse de l’analcime. Cette zéolithe est obtenue par cristallisation hydrothermale d’un gel d’aluminosi1icate sous pression et agitation permanente. Le produit se caractérise par un rapport Si/Al variant de 3,42 à 3,85 et un taux de cristallisation supérieur à 90 %. La phase cubique est prépondérante et présente un paramètre de maille de 13,7 Å. Dans de telles conditions opératoires, la pression semble jouer un rôle déterminant en réduisant le temps et la température de cristallisation

Effect of Isothermal Hold on the Microstructural Evolution of the Stainless Steel 304L/Zircaloy-4 Interface

International audienceThe transition from solid-state bonding of the stainless steel 304L/Zircaloy-4 diffusion couple to a partial liquid-phase bonding is important for the bonding process at temperatures ranging from 950 to 1050 degrees C. In this study, the temperature at which a melting process occurs at the interface after 45 min of isothermal holdings is determined experimentally. This melting process leads to a drastic change in the thickness of the reaction products zone (RPZ) as well as on its microstructure. Diffusion couples were characterized by SEM-EDS, and quantitative chemical analyses of different phases are performed by EPMA. The RPZ consists of three layers: the (alpha-Fe-Cr) phase layer and two layers consisting of Zr(Fe, Cr)(2) (epsilon), Zr-2(Fe, Ni) and (alpha-Zr) phases. The thickness of these layers strongly depends on the holding temperature. The analysis allowed the description of the physicochemical phenomena occurring during isothermal holding as well as during cooling. The solidification paths are determined at 1000, 1020 and 1050 degrees C. Hardness tests are performed on the bonded samples in order to qualify the mechanical properties of different phases of the RPZ. This study leads to a better understanding of the complex phenomena intervening in the joining process which is very useful for applications in industrial scale

A new hetero-junction p-CuO/n-ZnO for the removal of amoxicillin by photocatalysis under solar irradiation

International audienceThe main objective of this study was to evaluate the efficiency of a new hetero-junction p-CuO/n-ZnO assisted photo-catalytic process for the degradation of amoxicillin (AMX). The catalysts is synthesized by chemical route and characterized by X-ray diffraction, scanning electron microscopy (SEM), thermal analysis, BET specific surface area and photo-electrochemistry. The initial AMX concentration, photo-catalyst nature, catalyst dose and initial pH of the solution were optimized in order to evaluate the mineralization extent. AMX (50 mg/l) was almost entirely removed after 4 h of exposure to solar irradiation at pH similar to 11, by using the hetero-junction ZnO/CuO (50:50 wt%). The final AMX concentration was determined by high performance liquid chromatography (HPLC) equipped with a photodiode array detector. The analysis of NO(3)(-)and SO42- released by the degradation reaction were quantified by ionic chromatography and the total organic carbon (TOC) indicated a high mineralization degree of AMX. Kinetic analysis suggested that the AMX degradation obeys to a pseudo-first-order with a rate constant of 9.95 x 10(-3) min(-1). Finally, the application of this method was extended to real effluents. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Efeito do glutaraldeído na adsorção de extrato proteico da Ipomoea Batatas (L) Lam na superficie de uma zeólita analcima Effect of the glutaraldeide on the adsorption of proteic extract of the Ipomoea Batatas (L) Lam in analcime zeolite surface

A zeólita analcime (Na16Al16Si32O96.nH 2O) foi submetida a ataque ácido com HCl 0,25 mol.L-1, seguido da funcionalização com glutaraldeído, foi imersa em extrato protéico obtido da polpa da batata-doce (Ipomoea Batatas (L) Lam), que tem em sua composição a enzima polifenol oxidase (PFO). As amostras foram submetidas a procedimentos de caracterização por microscopia eletrônica de varredura, espectroscopia na região do infravermelho com transformada de Fourier e termogravimetria.<br>The analcime zeolite (Na16Al16Si32O96.nH2O) was treated with hydrochloric acid 0.25 mol.L-1, followed by the funcionalization with glutaraldehyde and immersed in the proteic extract obtained from gross extract of sweet potato pulp (Ipomoea Batatas (L) Lam), which presents in its composition the polyphenol oxidase enzyme (PPO). Other samples were submitted to the same procedure with characterizations by scanning electron microscopy, Fourier Transform Infrared spectroscopy and thermogravimetry