Experimental design for copper cementation process in fixed bed reactor using two-level factorial design

AbstractThis work deals with cementation of copper onto iron grid in a fixed bed reactor. The influence of several parameters is studied, namely: initial concentration of copper [Cu2+]0, temperature and flow rate. Moreover, their influence on the copper cementation reaction is investigated statistically by the experimental design in view of industrial application. The estimation and the comparison of the parameter’s effects are realized by using two-level factorial design. The analysis of these effects permits to state that the most influential factor is initial concentration of copper [Cu2+]0 with an effect of (+2.4566), the second in the order is the temperature with an effect of (+0.18959), the third is the flow rate of the electrolytic solution with an effect of (−0.4226). The significance interactions found by the design of experiments are between initial concentrations of copper ions–flow rate (x1x3) with an effect (b13=+0.6965)

Enhancement of the biodegradability of a mixture of dyes (methylene blue and basic yellow 28) using the electrochemical process on a glassy carbon electrode

International audienceThe coupling of an electrochemical process with a biological treatment for the degradation of methylene blue (MB) and basic yellow 28 (BY28) considered separately or in mixture on a glassy carbon electrode was examined in this study. It was shown that color removal efficiency and mineralization yield of MB, BY28, and their mixture increased with the working potential and decreased with the initial dye concentration. The optimal conditions were found to be E=2.4V/SCE, [MB](0)=50mg L-1, [BY28](0)=50mg L-1, pH=2, T=25 degrees C, and =600rpm, which led to 100% color removal after 120 and 240min of reaction time for BY28 and MB, respectively. Under these optimal conditions, the mineralization yield of BY28, MB, and their mixture (50mg L-1 of each dye) was close to 59, 57, and 54% within 360min of reaction time, respectively. The biological oxygen demand (BOD5)/chemical oxygen demand (COD) ratio increased substantially after 360min of pre-treatment from 0.04 to 0.27 for the dyes mixture. Microbial degradation was therefore performed for the pre-treated mixture solution and the results showed significant mineralization yield leading to an overall dissolved organic carbon decrease of 78% for the coupled process. It was therefore shown the presence of residual refractory compounds at the end of the culture which was illustrated by the decrease of the BOD5/COD ratio (0.045) obtained for the final solution. However, biodegradability was improved after a recycling of the solution in the electrochemical oxidation pre-treatment during 180min leading to a BOD5/COD ratio of 0.73

Investigation of Magneto Hydrodynamic Natural Convection Flows in a 3-D Rectangular Enclosure

The article deals with magnetic field of free convective flows in cavities similar to those used in artificial growth of single crystals from melts (horizontal Bridgman configurations) and having aspect ratios an equal to “4”. The combined effect of wall electrical conductivity and vertical direction of the magnetic field on the buoyancy induced flow of mercury was investigated numerically. The validation of the numerical method was achieved by comparison with both experimental and analytical data found in the literature. The plotted results for variation of velocity, temperature and Nusselt number in terms of the Hartmann number Ha and Rayleigh number “Ra” showed a considerable decrease in convection intensity as the magnetic field is increased, especially for values of “Gr” situated around 107. The calculations also showed that the vertically directed magnetic field (perpendicular to the x-z plane) is the most effective in controlling the flow and hence the speed of growth of the crystal. Also, wall electrical conductivity enhances damping by changing the distribution of the induced electric current to one which augments the magnitude of the Lorentz force

Effect of Sulfur Concentration on the Morphology of Carbon Nanofibers Produced from a Botanical Hydrocarbon

Carbon nanofibers (CNF) with diameters of 20–130 nm with different morphologies were obtained from a botanical hydrocarbon: Turpentine oil, using ferrocene as catalyst source and sulfur as a promoter by simple spray pyrolysis method at 1,000 °C. The influence of sulfur concentration on the morphology of the carbon nanofibers was investigated. SEM, TEM, Raman, TGA/DTA, and BET surface area were employed to characterize the as-prepared samples. TEM analysis confirms that as-prepared CNFs have a very sharp tip, bamboo shape, open end, hemispherical cap, pipe like morphology, and metal particle trapped inside the wide hollow core. It is observed that sulfur plays an important role to promote or inhibit the CNF growth. Addition of sulfur to the solution of ferrocene and turpentine oil mixture was found to be very effective in promoting the growth of CNF. Without addition of sulfur, carbonaceous product was very less and mainly soot was formed. At high concentration of sulfur inhibit the growth of CNFs. Hence the yield of CNFs was optimized for a given sulfur concentration

Phosphorus poisoning during wet oxidation of methane over Pd@CeO2/graphite model catalysts

10siThe influence of phosphorus and water on methane catalytic combustion was studied over Pd@CeO2 model catalysts supported on graphite, designed to be suitable for X-ray Photoelectron Spectroscopy/Synchrotron Radiation Photoelectron Spectroscopy (XPS/SRPES) analysis. In the absence of P, the catalyst was active for the methane oxidation reaction, although introduction of 15% H2O to the reaction mixture did cause reversible deactivation. In the presence of P, both thermal and chemical aging treatments resulted in partial loss of activity due to morphological transformation of the catalyst, as revealed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) analysis. At 600 °C the combined presence of PO43− and water vapor caused a rapid, irreversible deactivation of the catalyst. XPS/SRPES analysis, combined with operando X-ray Absorption Near Edge Structure (XANES) and AFM measurements, indicated that water induces severe aggregation of CeO2 nanoparticles, exposure of CePO4 on the outer layer of the aggregates and incorporation of the catalytic-active Pd nanoparticles into the bulk. This demonstrates a temperature-activated process for P-poisoning of oxidation catalysts in which water vapor plays a crucial role.partially_openembargoed_20171009Monai, Matteo; Montini, Tiziano; Melchionna, Michele; Duchoň, Tomáš; Kúš, Peter; Tsud, Nataliya; Prince, Kevin C.; Matolin, Vladimir; Gorte, Raymond J.; Fornasiero, PaoloMonai, Matteo; Montini, Tiziano; Melchionna, Michele; Duchoň, Tomáš; Kúš, Peter; Tsud, Nataliya; Prince, Kevin C.; Matolin, Vladimir; Gorte, Raymond J.; Fornasiero, Paol

Micro-entreprises et cadre institutionnel en Algérie

Ce document technique présente les résultats d'une enquête sur l'impact des réglementations juridiques et fiscales sur les micro-entreprises en Algérie. Le cas algérien se distingue de ceux des autres pays du programme de recherche (Niger, Swaziland, Tunisie, Thaïlande, Equateur, Jamaïque) car, en dépit de la stratégie d'ouverture adoptée par le gouvernement algérien dans les années 80, l'économie reste très réglementée. Trois secteurs ont été retenus, pour un échantillon d'environ 300 entreprises : la mécanique, le textile et la restauration. Leur étude permet de comparer le comportement d'entreprises opérant sur des marchés différents. L'enquête révèle que, dans l'ensemble, les obligations juridiques et fiscales sont respectées par une majorité de micro-entreprises ; les taux de respect les plus élevés sont ceux du secteur textile. Elle montre surtout que, quel que soit le secteur, le dynamisme des petits entrepreneurs interrogés est entravé par les lourdeurs de l'économie ...

Modeling of drying thin layer of tomato slices using solar and convective driers

This paper presents a mathematical modelling of thin layer drying of tomato (Solanum lycopersicum L.). To this end, two different methods are used to dehydrate tomato slices namely the solar drying (in an indirect solar dryer), and the forced convective drying (in a convective dryer). In the solar dryer, the experiments are carried out at a constant air velocity of 1 m/s and average temperatures of 37.2, 39.9, 42.5 °C. In the convective dryer, the experiments are performed with five different temperatures (30, 40, 50, 60 and 70 °C) at a constant air velocity of 1 m/s. In order to estimate and select the appropriate drying curve equation, fifteen different thin layer mathematical drying models available in the literature are applied to the experimental data. The models are compared using the correlation coefficient (r) and the standard error (s) and are predicted by a non-linear regression analysis using the Curve Expert software. The Midilli-Kucuk model shows a better fit to the experimental drying data according to (r) and (s) for the two drying methods. The effect of the drying temperature on the parameters of this model is also determined. The experimental drying curves show only a falling drying rate period. On average, tomatoes are dried until the moisture content of 0.15 kg water/kg dry matter from 14.36 kg water/kg dry matter in the solar drying, and to the moisture content of 0.10 kg water/kg dry matter from 12.66 kg water/kg dry matter in the convective drying.