Publications Internationales
Permanent URI for this collectionhttps://dspace.univ-boumerdes.dz/handle/123456789/13
Browse
10 results
Search Results
Item Oxidation and property evolution of AISI T5 steel under varying heat treatments(2025) Dadou, Abdenour; Dilmi, Hamid; Bezzazi, Boudjema; Aribi, Chouaib; Daoud, IsmailThis study evaluates the effect of heat treatment on the mechanical, tribological, and oxidation behavior of AISI T5 steel. The chemical composition was first characterized using spectroscopy and SEM. A two-year oxidation test conducted in humid and relatively dry atmospheres showed strong environmental sensitivity: in humid air, the oxidation rate reached 11.27×10-2 P/P0 per month with a sharp increase after 25 days, whereas in dry air it remained below1.35×10-2 P/P0 per month, following a linear and nearly flat trend indicative of a protective oxide scale. Heat treatment significantly increased hardness from 34.15 ± 0.59 HRC (untreated) to 62.70 ± 0.66 and 60.80 ± 0.48 HRC for water and oil quenched steels, respectively. Impact strength decreased accordingly, with oil quenching offering the best hardness-toughness balance (60.8 HRC, 2.08 Kcv). Instrumented indentation confirmed substantial surface strengthening, with HIT rising to 17.39 ± 0.29 uced by 81.3% (Q. Water) and 62.5% (Q. Oil), with faster run-in in the water-quenched condition. XRD revealed tempered martensite with Fe3W3C/Cr7C3 (Q. Water) and Co3W3C (Q. Oil), consistent with thermal conditions. This study provides new experimental data on the effects of 15-minute austenitization followed by oil or water quenching on the properties of AISI T5 steel, highlighting its potential for process optimization.Item Cyanide Removal from Aqueous Solution by Oxidation with Hydrogen Peroxide Catalyzed by Copper-Zinc Oxide Nanoparticles(Springer Nature, 2024) Boutrif, Abderrahamane; Chergui, Salima; Halet, Farid; Chergui, Abdelmalek; Boudriche, Lilya; Ould-Dris, Aïssa; Nadjemi, Boubekeur; Yeddou, Ahmed RedaThis work is concerned with the cyanide removal from aqueous solution by oxidation with hydrogen peroxide H2O2 catalyzed by copper zinc oxide (CuO-ZnO) nanoparticles prepared by co-precipitation method. The influences of catalyst dose, hydrogen peroxide concentration, temperature, and catalyst stability on cyanide removal were examined. The use of CuO-ZnO nanoparticles made it possible to increase the reaction rate, thus showing good catalytic activity. The cyanide removal percentage was increased after 75 minutes of reaction time from 70% to 100% by raising the catalyst dose from 0.25 g/L to 1.0 g/L. Increasing the temperature from 24 °C to 35 °C enhanced cyanide removal rate, the apparent activation energy was then found to be equal to 48 KJ/mol. The nanocatalyst was used again for four successive times and exhibited good stability. The kinetics of cyanide elimination was found to be pseudo-first order with respect to cyanide.Item Cyanide removal from aqueous solution by oxidation with hydrogen peroxide in the presence of activated alumina-supported copper catalyst(Global NEST, 2024) Halet, Farid; Chergui, Salima; Hamdache, Farida; Boutrif, Abderrahmane; Chergui, Abdelmalek; Ould-Dris, Aissa; Boudriche, Lylia; Guénin, Erwan; Nadjemi, Boubekeur; Yeddou, Ahmed RedaCyanide compounds are widely used in some electroplating, chemical, and metallurgical industries. They are often found in their liquid discharges. This work highlights the performance of an activated alumina-supported copper catalyst in the removal of cyanide by oxidation with hydrogen peroxide in aqueous solution. The influence of catalyst dose, initial molar ratio of hydrogen peroxide/cyanides, temperature, and catalyst reuse was studied. The activated alumina-supported copper significantly enhanced the reaction rate showing a good catalytic activity. The efficiency of cyanide elimination was increased after 30 minutes of oxidation from 48% to 98% by increasing the catalyst dose from 1 to 10 g/L. Rising the temperature from 30°C to 40°C promoted cyanide removal. The catalyst can be recycled four times and show good stability. The kinetics of cyanide oxidation was revealed to be pseudo-first-order regarding cyanides. The rate constants as well as the activation energy were determined.Item 1,4-Dimethoxybutadienediyl-Bridged diiron compounds in three oxidation states : evaluation of delocalization effects(American Chemical Society, 2019) Sahnoune, Hiba; Mahias, Virginie; Halet, Jean-François; Lapinte, ClaudeThe binuclear iron complexes [Cp∗(PMe3)(CO)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(PMe3)(CO)Cp∗] (1meso and 1dl) were prepared by double deprotonation of their known parents [Cp∗(PMe3)(CO)Fe=C(OCH3)CH2-CH2-C(OCH3)=Fe(PMe3)(CO)Cp∗](PF6)2 (5meso and 5dl) and were isolated in good yield (90%). These complexes were characterized by ESI-mass spectrometry, IR and multinuclear NMR spectroscopy, and cyclic voltammetry. The singly and doubly oxidized forms 1meso(PF6)n and 1dl(PF6)n (n = 1, 2) were prepared by oxidation of the parent neutral complexes with 1 and 2 equiv of ferrocenium salt (93-100% yield). The related complex [Cp∗(dppe)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(dppe)Cp∗](PF6) (2(PF6)) was obtained by reduction of the known dicationic derivative [Cp∗(dppe)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(dppe)Cp∗](PF6) (2(PF6)2) with 1 equiv of cobaltocene (100% yield). Multinuclear NMR spectroscopy allowed us to establish the diiron(II) conjugated μ-bis(carbene) structure for 1meso(PF6)2 and 1dl(PF6)2. In the case of the meso derivative, 1H NMR revealed the presence of E and Z isomers in a 4:1 ratio, confirming the presence of a C=C double bond in the middle of the bridge. The three radicals 1meso(PF6), 1dl(PF6), and 2(PF6), which are thermally stable, were analyzed by IR, Mössbauer, ESR, UV-vis, and NIR spectroscopy. Experimental data, discussed with the support of quantum chemistry calculations performed at the DFT level of theory, indicate that these radical cations exhibit characteristics of oxidation on the butadienediyl bridge rather than on the metal centersItem Characterization and transformation of the Opuntia ficus indica fruits(Springer US, 2018) Idir, Lamia; Zouhir, Cherrared; Amir, YoucefOpuntia ficus indica fruits have been associated with health effects, due to their protective actions against oxidation. Nevertheless, few studies about processing of Opuntia fruits are available’; therefore, we studied the pulp characteristics and processing of a local variety, for producing beverage nectars. The pulp had an average pH of 5.64, 13.47 °Brix, with total sugars (106 g L−1), K (1180 mg L−1), 503.3 µg L−1 of β carotene, 120 mg L−1 of total phenolic compounds, 4.9 mg and 46.9 mg L−1 respectively for betacyanins and betaxanthins and 243.4 mg L−1 of vitamin C. The formulated nectars with 35% of pulp (N35) and 45% of pulp (N45) had respectively 14 and 15 °Brix. Minor components represent 1109 and 1112 mg L−1 of K for N35 and N45 respectively, β carotene (318.6 µg and 362.8 µg L−1), and vitamin C 227 and 231 mg L−1. We confirmed the stability and acceptability of these beverages after a month of storage, after stability and panel tests. Therefore, we suggest that the pulp processing can be used as a new form of agro industrial utilization of this underutilized fruitItem Copper(II) complex of a Schiff base of dehydroacetic acid: Characterization and aerobic oxidation of benzyl alcohol(Elsevier, 2016) Benferrah, Nassima; Hammadi, Mohamed; Philouze, Christian; Berthiol, FlorianItem The dicalcium phosphate dihydrate Fixator and Stabilizer of Glutaraldehyde(2014) Bouzid, Mohammed; Djadi, Amina; Guechtoulli, SamiraThe dicalcium phosphate dihydrate (A) reacts with glutaraldehyde (B) in aqueous solution with a yield of 95%. The resulting product (C) is chemically stable. The obtained purity is checked by UV-Visible and the structure is discussed on the basis of the Infrared absorption FTIR. The reaction mechanism is explained by the approach of the hydroxyl group (-OH) of one of the aldehyde functions (-CO) of 1.5 dipentanal with the enolic form, which stabilizes the product (C). The reversible reaction is performed by mild oxidation of the compound (C) in aqueous medium at ambient temperature. The compound (A) is generated with high efficiency. The comparative spectral and thermography study confirms this resultItem Removal of cyanide in aqueous solution by oxidation with hydrogen peroxide in presence of activated carbon prepared from olive stones(Elsevier, 2010) Yeddou, Ahmed Reda; Nadjemi, Boubakeur; Halet, Farid; Ould-Dris, Aïssa; Capart, RichardItem Removal of cyanide in aqueous solution by oxidation with hydrogen peroxide in presence of activated alumina(Taylor and Francis, 2015) Chergui, Salima; Yeddou, Ahmed Réda; Chergui, Abdelmalek; Halet, Farid; Amaouche, Hamza; Nadjemi, Boubekeur; Ould-Dris, AïssaItem Removal of cyanide in aqueous solution by oxidation with hydrogen peroxide in presence of copper-impregnated activated carbon(Elsevier, 2011) Yeddou, Ahmed Reda; Chergui, Salima; Chergui, Abdelmalek; Halet, Farid; Amaouche, Hamza; Nadjemi, Boubekeur; Ould-Dris, Aïssa; Belkouch, Jamal