Liste des documents
Photocatalytically-assisted electrooxidation of herbicide fenuron usinga new bifunctional electrode PbO2/SnO2-Sb2O3/Ti//Ti/TiO2
The degradation of the herbicide fenuron was investigated using a new porous bifunctional electrodewhere the electrooxidation takes place on one side and the photocatalysis on the other side. The characterizationof the synthetized bifunctional electrode (PbO2/SnO2-Sb2O3/Ti//Ti/TiO2) was performed byscanning electron microscopy, energy dispersive X-ray spectrometry and X-ray diffraction analysis andshowed that the anodic side (Ti/SnO2-Sb2O3/PbO2) is covered with a tetragonal b-PbO2 film and that thephotocatalytic side (Ti/TiO2) consists of an anatase phase of TiO2. The single application of electrooxidationachieved 87.8% fenuron degradation and 84.1% chemical oxygen demand (COD) removal whileheterogeneous photocatalysis resulted in only 59.2% and 39.7% fenuron concentration decay and CODremoval, respectively. On the other hand, the photocatalytically-assisted electrooxidation (photo-electrooxidation)performed on the bifunctional electrode provided higher performances of fenurondegradation (97.5%) and mineralization (97.4%). Investigation of operating parameters highlighted thepositive effect of increase in current density. Conversely, an increase in fenuron concentration led to adecrease in degradation rate and COD removal. It was also found that the COD removal and mineralizationefficiency are higher in a neutral medium. Voir les détails
Mots clés : Fenuron Bifunctional electrode Lead dioxide anode Electrooxidation Photo-electrooxidation
Copper removal in solution by sawdust: kinetic and thermodynamic study
This study presents the results obtained when okoumé sawdust is used for the removalof copper contained in wastewater. The tests show that one gram of sawdust can fix29.56 mg of copper, according to the Langmuir model with kinetics of the pseudo firstorder where the time of the pseudo equilibrium is reached after 40 minutes of agitation.The elimination is envisaged in batch mode, at 20 ° C, a stirring speed of 200 rpm, atpH value of 4.4 and a particle size between 500 ≤ Ø < 700μm. Measured results alsoreveal that external diffusion controls the speed of the overall process of adsorption anddiffusion into the pores is not the only mechanism limiting kinetics. The thermodynamicstudy shows that this sorption is spontaneous , exothermic and that no changes havebeen made in the structure of the sawdust Voir les détails
Mots clés : Cooper, adsorption, sawdust, water, pollution
Tribological behaviour of a continuous hot dip galvanized steel
The aim of this work is to investigate the tribological behaviour of a continuous hot dip galvanizedsteel. This paper presents a fundamental study of the characteristics of zinc coating in terms ofmorphology, surface roughness and tribological behavior according to process parameters typical ofindustrial processes continuous galvanization. The morphology of the zinc coating was observed byscanning electron microscope (SEM), optical microscopy, and the mechanical properties of thecoating layers were determined by nanoindentation. The tribological tests were carried out on arotating ball-disk tribometer under loads of 1, 2, 3Nwith a sliding distance of 15, 30 and 50 m. Theresults showed a marked increase of the coefficient of friction with increasing applied load. Under thesame conditions, wear slightly increased due to the hardness of intermetallic phases. The resultspresented show that heating promotes the diffusion of iron in the zinc coating giving shape to a binaryalloy Fe–Zn whose characteristics depend on the parameters; moreover, it is proved that thetribological characteristics of the surface of the metal blank in terms of coefficient of friction dependon the temperature of the contact pressure. Voir les détails
Mots clés : galvanized steel, wear, roughness, Nanoindentation, intermetallic phases
Thermal Treatment Effect on Tribological and Corrosion Performances of 13Cr5Ni2Mo Super- Martensitic Stainless Steel
Wear behavior of 13Cr5Ni2Mo supermartensitic stainless steel (SMSS) were investigated in air and in argillaceous paste at room temperature. Prior to wear testing, the samples were subjected to two treatments, namely; quenching followed by double tempering. A pin-on- disc test rig was used to conduct the wear test with a tribo-pair consisting of supermartensitic stainless steel sliding against itself. It was observed that the microstructure of the thermally treated samples mainly consisted of tempered martensite and carbides. Wear results showed that oxidative and abrasive wear dominated the wear process of the treated samples in both dry conditions and in argillaceous paste. Additionally corrosion tests were performed in 5.0% NaCl solution via potentiodynamic polarization tests. It was found that the passive film formation provides a good corrosion resistance to the samples. Voir les détails
Mots clés : Martensitic Stainless Steel, Thermal Treatments, wear, corrosion
Degradation of C.I. Acid Red 51 and C.I. Acid Blue 74 in Aqueous Solution by Combination of Hydrogen Peroxide, Nanocrystallite Zinc Oxide and Ultrasound Irradiation
Journal of Advanced Oxidation Technologies2018; 21(1)www.jaots.netDOI:10.26802/jaots.2017.0022Journal of Advanced Oxidation Technologies 2018; 21(1)Article ID-20170022Article:Degradation of C.I. Acid Red 51 and C.I. Acid Blue 74 in Aqueous Solution by Combination of Hydrogen Peroxide, Nanocrystallite Zinc Oxide and Ultrasound IrradiationInsaf Ould Brahim*1,3, Mohamed Belmedani1,Ahmed Haddad3, Hocine Hadoun2,Ahmed Belgacem11Laboratory of transfer phenomena, Faculty of Mechanical and Processes Engineering, University of Sciences and Technology Houari Boumediene, BP n 32 El Alia bab ezzouar 16111 Algiers, Algeria2Nuclear Research Center of Algiers, 2 Bd Frantz Fanon, 16035, Algiers, Algeria3Research Center in Industrial TechnologiesCRTI, P.O.Box 64, Cheraga 16014 Algiers, Algeria *iouldbrahim@gmail.comPhone: 00213-20-77-67Fax: 00213-21-34 -20-19AbstractThis study illustrates the degradation of food dyes, C.I. Acid Red 51 (erythrosine E127) and C.I. Acid Blue 74 (indigo carmine E132) by sonocatalysis using an ultrasonic frequency of 37 kHz and a power of 150 W in the presence of heterogeneous catalysts ZnO and peroxide hydrogen (H2O2). The adsorption process for the two dyes on the ZnO nanocrystalline which satisfies the Freundlich model appears not effective because the elimination of the two food dyes does not exceed 35%. In order to improve the removal, the sonocatalytic process (AD-OX) has been investigated. At this purpose, effect of operating parameters such as initial dye concentrations, H2O2(0-0.75M) and initial pH on the sonochemical degradation was investigated. It was observed that when the adsorption-catalysis was assisted by the ultrasonic and H2O2 a considerable yields has been achieved and about 86% and 97% of E127 and E132 were removed for 10 mg L-1and 50 mg L-1respectively. To understand the behavior of dye degradation, structure of the zinc catalyst before and after the sonocatalytic process was characterized by meanX-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM).Results showed thatthe ZnO particles before and after sonocatalysis were crystallized in the hexagonal wurtzite phase and the size distribution indicates that most of the particles are in the range of 300 and 600 nm. Finally, ADMI and COD analysis were performed in order toquantify the residual color in solution and evaluate the efficiency of the dye mineralization. Results showed that the treatment of food dyes by US-ZnO-H2O2process increased color degradation (ADMI)and mineralization efficiency (COD) by more than 50% and 76% respectively. Voir les détails
Mots clés : Advanced oxidation process, sonocatalysis
ZnO nanoparticles and biocidal effect of nanostructured ZnO filmson Escherichia coli
The biocidal effect of ZnO nanostructured films was studied using Escherichia coli ATCC 43897. TheZnO nanoparticles were synthesized in diethylene glycol by using zinc acetate forced hydrolysis.X-ray diffraction analysis confirmed the formation of single wurtzite-type ZnO phase with a crystallitesize of 20.59 nm. Transmission electron microscopy observations revealed spherical-shaped particlesin the nanoscale regime with a mean particle size of 21.96 nm. It was found that the addition oftrioctylphosphine during synthesis favored much improved dispersion of ZnO nanoparticles, withsmaller particle size; that is, 16.28 nm. Meanwhile, ZnO film grown onto glass substrate by spin-coatingrevealed single phase with the formation of aggregates (≈700) having mushroom-like morphologyformed of very fine particles in the nanoscale regime. The as-deposited nanostructured films exhibiteda hydrophilic character. The classical bacteriological and electrochemical impedance spectroscopymeasurements enabled the biocidal effect of ZnO nanostructured films with 94% inactivation efficiencyafter 90 min of contact time. Voir les détails
Mots clés : ZnO; Spin-coating; Nanostructured film; Biocide effect; E. coli; EIS
Mechanism for phosphorus deactivation in silicon-based Schottkydiodes submitted to MW-ECR hydrogen plasma
Current work reveals the deactivation mechanism of phosphorus in silicon-based Schottky diodes. Microwave plasma power(P) was fixed at 650 W to observe the variation in different operational parameters of diodes such as initial phosphorusconcentration, flux and hydrogenation temperature (TMWH) and process time (t). The analysis of variation in concentrationof phosphorus by hydrogenation has been carried out by capacitance–voltage (C–V) measurements to monitor the dopingactivation/deactivation. The results clearly show that the atomic species H+H is dominant in the reactors MW-ECR plasma.Therefore, the rates and depth of neutralization were obtained in the low phosphorus-doped silicon sample. The H becomesH0 and prefers an interaction with another H0 instead of gaining an electron to become a negative ion. The hydrogenationtemperature study indicates that the deactivation rate of phosphorus is achieved in a complex manner. Indeed, as the hydrogenationtemperatureincreases,deactivationof phosphorus also increasestill saturationat 250 °C.Athigher temperature,lowor evenno phosphorus–hydrogen complexexistsdue totheirthermaldissociation. The same behaviorwasconfirmedbylonghydrogenation. Voir les détails
Mots clés : MW-ECR plasma, Hydrogenation, phosphorus deactivation, C–V measurement
Dissimilar Welding between 2205 Duplex Stainless Steel and API X52High Strength Low Alloy Steel
This work purposes to investigate the microstructure and the mechanical behavior ofdissimilar metals weld between 2205 duplex stainless steel (UNS 31803) and high strength lowalloy steel API X52. The joining was produced by shielded metal arc welding process using twodifferent filler metals, the duplex E2209 and austenitic E309 grade.The microstructures of the dissimilar welded joints have been investigated by optical microscopy,scanning electron microscopy and energy-dispersive spectroscopy (EDS). The EDS analysisperformed at the API X52/weld metal interface showed an evident gradient of Cr and Ni betweenfusion and type II boundaries, where the highest hardness value was recorded. Voir les détails
Mots clés : Dissimilar metals welding; 2205 duplex stainless steel; API X52 HSLA steel; Heataffected zone
Study of thin Films of Nickel Oxide (NiO) Deposited bythe Spray Pyrolysis Method
Abstract: In this work, thin films of nickel oxide (NiO) were deposited by a simple and inexpensive technique, which is spraypyrolysis on ordinary glass substrates heated to a fixed temperature of 500 °C, from a solution containing nickel nitrate hexahydrateas a precursor dissolved in distilled water with deferent values of concentrations. The NiO thin films obtained were characterized todetermine the structure with X-ray diffraction technique (XRD), the absorption domain (UV-Visible Spectroscopy), and the surfacemorphology (SEM). The X-ray diffraction patterns confirm the presence of NiO phase with preferential orientation along the (111)direction. The optical gap for nickel oxide calculated with a concentration of 0.1 M from the measurement of optical absorption is 3.6eV, which is quite comparable to the value of the ratio. Voir les détails
Mots clés : NiO, Thin films, Spray pyrolysis
Rhodamine (B) photocatalysis under solar light on high crystallineZnO films grown by home-made DC sputtering.
ZnO thin films were deposited by home-made DC sputtering of zinc target under mixed gases(Argon, Oxygen) plasma on glass substrates. Films were deposited by varying oxygen partialpressure (PO2) from 0.09 to 1.3 mbar in the deposition chamber, at a fixed substrate temperatureof 100 °C. The samples were characterized by photoluminescence (PL), X-ray diffraction (XRD),optical transmissions (UV–vis), scanning electron microscopy (SEM) and electrical (Hall effect)measurements. The results indicate that by varying the oxygen pressure in the depositionchamber, the films show a precise and well defined photoluminescence emissions for each rangeof pressure covering almost the entire visible domain (UV, UV-Violet, Violet, Blue, and Red) withhigh intensities. Moreover, the deposited films have different defects levels. The XRD analysisindicates that the films are well grown along the c-axis peak, but with different crystallinequality. Optical measurements reveal a high transmission, up to 90%, in the spectral regionbetween 400 and 2500 nm and a large variation of the optical band gap (3.16 – 4.34 eV). As anapplication of the deposited ZnO films, the photo-catalytic degradation of a synthetic solution ofRhodamine B (RhB) poured on a ZnO thin film was successfully achieved and an elimination rateof 38% was obtained after exposing the film to solar light for 3 h. Voir les détails
Mots clés : ZnO thin films, sputtering, Photoluminescence, Rhodamine (B), Solar light, Photocatalysis.