Publications Scientifiques
Permanent URI for this communityhttps://dspace.univ-boumerdes.dz/handle/123456789/10
Browse
14 results
Search Results
Item The significant effect of K+ counterion in the enhancement of physicochemical and structural properties of amorphous aluminosilicates xerogels used as catalysts in the transesterification of waste frying oils(Taylor & Francis, 2023) Boufellah, Nassima; Aksas, HammoucheWith the aim of better directing the polycondensation of oligomers during the synthesis of amorphous aluminosilicate xerogels by the sol-gel process using Na2SiO3, we reinforced the sols with Kþ counterion and studied its effect on the physicochemical and structural properties of the xerogels using XRD, FTIR, N2 physisorption, SEM, EDX, and TGA techniques as well as quantitative analysis of the acid sites by N-butylamine adsorption followed by potentiometric titration. Based on the results, the introduction of Kþ generated xerogels with good porosity and conferred resist- ance to matrix cracking. The amorphous character of the xerogels did not change after adding Kþ. FTIR spectra showed that the composition of the xerogels was improved after the addition of Kþ. Cation exchange and sulfur removal were much more efficient in the presence of Kþ which improved the acidity of the xerogels. The best percentages of Si and Al were observed at the Naþ/Kþ ratios of 4 and 1.The enhanced xerogel prepared with Naþ/Kþ ratio of 1 gave a biodiesel yield of 80.44% at the optimum parameters and was used for three reaction cycles without signifi- cant loss of biodiesel yield.Item Optimization of a dermatological cream process formulation from Atractilys Gummifera L roots(Aljest, 2021) Larid, R.; Aksas, Hammouche; Touzouirt, S.; Hocine, I.; Kerbouche, R.; Abbadi, M.E.Atractilys Gummifera L or glue thistle,is one of the medicinal plants of the Mediterranean area. Belonging to the Asteraceae family, it is used in traditional medicine in various ways (maceration, decoction and fumigation). The rhizome of this plant is used as a healing agent in traditional Algerian medicine: it helps to heal burns. The aim of our work is to optimize the formulation process of a cream for dermatological application based on the roots of Atractilys Gummifera L, by using the methodology of experimental design. The physicochemical characterization of the underground part of this plant reveals a richness in organic substances (sugars 8.5%, lipids 2.29%, Brix degrees 33.34%), and mineral substances (ashes 4.21%). The study of the various parameters considered influential on the formulation process revealed that the optimal conditions for a more stable cream are: the solid (rhizome) / liquid (water) ratio 0.4 (m / V), the stirring time for 15 minutes and the stirring speed 500 rpm. The cream obtained has a rheofluidic (or pseudoplastic) behaviour, which can be described by the Casson model. This behaviour is suitable for a cream for dermatological applicationItem Carbon nanotubes (CNTs) from synthesis to functionalized (CNTs) using conventional and new chemical approaches(2021) Lakhdar, Sidi Salah; Ouslimani, Nassira; Bousba, Dalila; Huynen, Isabelle; Danlée, Yann; Aksas, HammoucheCarbon nanotubes (CNTs) have emerged worldwide because of their remarkable properties enlarging their field of applications. Functionalization of CNTs is a convenient strategy to tackle low dispersion and solubilization of CNTs in many solvents or polymers. It can be done by covalent or noncovalent surface functionalization that is briefly discussed regarding the current literature. Endohedral and exohedral are conventional methods based on covalent and van der Waals bonding forces that are created through CNT functionalization by various materials. In this paper, a review of new approaches and mechanisms of functionalization of CNTs is proposed, including amidation, fluorination, bromination, chlorination, hydrogenation, and electrophilic addition. Our analysis is supported by several characterization methods highlighting recent improvements hence extending the range of applicability of CNTs.Item Treatment and modeling of industrial liquid effluent adsorption isotherm on plant-based materials(Aljest, 2021) Chaouadi, Hiba; Aksas, HammoucheMargins are not degradable due to the presence of substances (phenols, volatile fatty acids, etc.), which pose problems for the environment. In order to protect our environment, and currently know various treatment pathways such as adsorption, we studied the effects of diethylaminoethyl-cellulose (DEAE-ellulose) on the constituents of a gem and studied the adsorption power of DEAEcellulose of phenolic compounds present in the gills of Tadmait willaya Tizi-Ouzou. The latter showed that the best adsorption conditions are simple to achieve: temperature of 22°C, direct use of the margin (Vm = 10 ml, pH = 4.5) in rather large quantities compared to that of the adsorbent (mass ratio = 10) and that the Freundlich model better represents the adsorption of the phenolic compounds of the margin on the DEAE cellulose. Infrared spectroscopy analyzes showed the complex composition of the margin in various organic constituents. MEB- EDS microscopy analyzes revealed amorphous morphologies of the cellulose and the dry matter of the marginItem Carbon nanotubes (CNTs) from synthesis to functionalized (CNTs) using conventional and new chemical approaches(Hindawi Limited, 2021) Salah, Lakhdar Sidi; Ousliman, Nassira; Bousba, Dalila; Huynen, Isabelle; Danlée, Yann; Aksas, HammoucheCarbon nanotubes (CNTs) have emerged worldwide because of their remarkable properties enlarging their field of applications. Functionalization of CNTs is a convenient strategy to tackle low dispersion and solubilization of CNTs in many solvents or polymers. It can be done by covalent or noncovalent surface functionalization that is briefly discussed regarding the current literature. Endohedral and exohedral are conventional methods based on covalent and van der Waals bonding forces that are created through CNT functionalization by various materials. In this paper, a review of new approaches and mechanisms of functionalization of CNTs is proposed, including amidation, fluorination, bromination, chlorination, hydrogenation, and electrophilic addition. Our analysis is supported by several characterization methods highlighting recent improvements hence extending the range of applicability of CNTItem Predictive optimization of electrical conductivity of polycarbonate composites at different concentrations of carbon nanotubes: A valorization of conductive nanocomposite theoretical models(MDPI, 2021) Sidi Salah, Lakhdar; Ouslimani, Nassira; Chouai, Mohamed; Danlée, Yann; Huynen, Isabelle; Aksas, HammouchePolycarbonate—carbon nanotube (PC-CNT) conductive composites containing CNT concentration covering 0.25–4.5 wt.% were prepared by melt blending extrusion. The alternating current (AC) conductivity of the composites has been investigated. The percolation threshold of the PC-CNT composites was theoretically determined using the classical theory of percolation followed by numerical analysis, quantifying the conductivity of PC-CNT at the critical volume CNT concentration. Different theoretical models like Bueche, McCullough and Mamunya have been applied to predict the AC conductivity of the composites using a hyperparameter optimization method. Through multiple series of the hyperparameter optimization process, it was found that McCullough and Mamunya theoretical models for electrical conductivity fit remarkably with our experimental results; the degree of chain branching and the aspect ratio are estimated to be 0.91 and 167 according to these models. The development of a new model based on a modified Sohi model is in good agreement with our data, with a coefficient of determination R2 = 0.922 for an optimized design model. The conductivity is correlated to the electromagnetic absorption (EM) index showing a fine fit with Steffen–Boltzmann (SB) model, indicating the ultimate CNTs volume concentration for microwave absorption at the studied frequency range. © 2021 by the authors. Licensee MDPI, Basel, SwitzerlandItem Etude potentielle de mélange des adsorbants naturels (grignons d’olive et noyaux de dattes) pour l’adsorption du chrome(Aljest, 2016) Aksas, Hammouche; Cherifi-Nacy, H.; Babaci, N.; Louhab, K.Cette étude a pour objectif d’étudier le potentiel d’utilisation de matériaux naturels (mélange homogène de noyaux de dattes et de grignons d’olives) issus de l’activité d’agriculture pour le traitement des eaux usées, chargées en polluant métallique: le chrome. Ces deux matériaux ont été activés chimiquement par l’acide phosphorique, en les mélangeant à différents pourcentages, afin d’obtenir une solution solide homogène et d’améliorer leur capacité adsorptive. L’adsorption des ions du chrome est étudiée en milieu dispersé (batch) à la fois sur les matériaux pur et à l’état du mélange à différentes proportions, composées d’une quantité fixe en noyaux de dattes (ND), et des quantités du grignon d’olive (GO) variées. Les résultats d’adsorption du chrome montrent : qu’elle est maximale à un pH =5.6, croit avec la température et avec la concentration initiale du chrome dans la solution. Le modèle de Langmuir stimule mieux les isothermes d’adsorption du chrome que d’autres modèles étudiés (avec un coefficient de corrélation de 0.9988 pour (88% NDI, 12% GOI). L’adsorption du chrome augmente avec l’augmentation du taux du grignon d’olive dans le mélange d’adsorbant (grignon d’olive et noyau de date).Item Enviornmentalimpact of Algerian cement factories on fauna and flora(Asian Publication Corporation, 2017) Aksas, Hammouche; Boughrara, S.; Louhab, K.The aim of this study is to evaluate the environmental impact of atmospheric emission of two kinds of cement portland processes in the Algerian factories on fauna and flora. The first uses the dry process and is located in a rural area (Sour El Ghozlane) and sec ond is in an urban area (Rais Hamidou) and uses the wet process. To evaluate the atmospheric impacts generated by the cement factories, life cycle assessment approach is applied using Simparo 7.1 software and EDIP method. A comparative study of the impacts evaluated for the se processes and the contribution of the compound for all impact categories were determinedItem Design and optimization of a CPW-fed tri-band patch antenna using genetic algorithms(Applied Computational Electromagnetics Society (ACES), 2015) Fertas, K.; Kimouche, H.; Challal, Mouloud; Aksas, Hammouche; Aksas, R.; Azrar, ArabItem Kinetics and thermodynamics of cr ions sorption on mixed sorbents prepared from olive stone and date pit from aqueous solution(2012) Aksas, Hammouche; Boureghda, M.Z.; Babaci, Hakima; Louhab, K.