Research on environmental impact assessment of flame oxyacetylene welding processes

This paper presents the factors that may cause pollution of the work environment when working with the oxyacetylene flame welding process. Experiments were performed using an oven that allows the analysis of all gases resulted in the welding process, but also enables their monitoring using a video camera, and the resulting film was processed in that the frames for each second of experimentation were extracted. The materials used in the experiments were S235JR steel as the base material, and as filler materials, E70S. In order to assess the impact on the work environment of this welding process, the pollution coefficient CP was defined based on the equation of the material balance

Bimetallic Au-Pd and Ag-Pd Clusters Synthesised by

Ag-Pd and Au-Pd (alloyed or core-shell) catalysts were synthesised by radiolytic reduction (gamma rays or electron beam). Selective hydrogenation of buta-1,3-diene was performed with these different nanoparticles deposited on alumina in order to investigate composition and structure effects on catalytic performances. Au-Pd and Ag-Pd nanoparticles exhibit very different catalytic behaviours: whereas only hydrogenation activity is modified on Au-Pd systems without any change in selectivity toward butenes formation, important variations in selectivity into butenes are observed for Ag-Pd nanoparticles deposited on alumina support

Corrosion behavior of some timonb alloys in ringer solution

International audienceThe aim of this study was to investigate the influence of different process parameters as chemical composition, the pH value and immersion time on the corrosion of the some TiMoNb alloys, using different electrochemical techniques such as: cyclic voltammetry, open circuit potential (OCP) measurement, polarization curves and electrochemical impedance spectroscopy (EIS). The alloys were analyzed in the natural pH of the Ringer solution, but also with an acidic modification of the solution (ph = 4) and a basic modification (ph = 8). The more acidic values of pH, the more evident are differences between corrosion behavior of titanium-based alloys depending on their chemical compositions and immersion times. © 2020 SYSCOM 18 S.R.L.. All rights reserved

Enhanced of TiO2-Ag photocatalysis performance for removal of methylene blue in presence of acetone

International audienceIn the present study, the photocatalytic degradation of methylene blue (MB), using TiO2-Ag synthesized by sol-gel method, as a catalyst under UV light, was studied. The samples synthesized were characterized by SEM, EDAX, FTIR, XRD and TEM. The average size of the particles was 10 nm. Tests were carried out in a batch reactor, magnetically stirred, with external irradiation using UVB lamp of Hg - 18 W, having intensity of incident radiation 2.1 W/m2. The effects of some parameters, such as catalyst dosage, pH and initial acetone concentration were investigated. Results showed that the optimal catalyst concentration was 0.03 g/L, at concentration of MB solution of 1.25∙10-5 mol/L. The mechanism of degradation of MB in presence of acetone was proposed. The results obtained in this work are very promising, using TiO2-Ag as photocatalyst, especially in presence of acetone as photosensitizer, when degradation percentage increases from 60% for TiO2 without Ag to 92.38% for TiO2-Ag and 0.1% acetone and 97.25% for 0.2% acetone. The photocatalysis followed pseudo-first order reaction kinetic behaviour, with the rate constants ranging from 0.0009 to 0.11 min-1 under the studied conditions. The reaction rate depends nonlinear of acetone concentration, the constants of polynomial function being calculated