Touhami Mokrani

Microwave-assisted synthesis of simonkolleite nanoplatelets on nickel foam-graphene with enhanced surface area for high-performance supercapacitors

Simonkolleite (Zn5(OH)8Cl2·H2O) nanoplatelets has been deposited on nickel foam-supported graphene by using an efficient microwave-assisted hydrothermal method. The three-dimensional (3D) porous microstructure of the as-fabricated nickel foam-graphene/simonkolleite (NiF-G/SimonK) composite is beneficial to electrolyte penetration and ions exchange, whereas graphene provide improved electronic conductivity. Structural and morphological characterizations confirmed the presence of highly crystalline hexagonal-shaped nanoplatelets of simonkolleite. Field emission scanning electron microscope (FE-SEM) of the NiF-G/SimonK composite revealed that the SimonK nanoplatelets were evenly distributed on the surface of NiF-G and interlaced with each other, resulting in a higher specific surface area of 35.69 m(2) g(-1) compared to SimonK deposited directly on NiF 17.2 m(2) g(-1). Electrochemical measurements demonstrated that the NiF-G/SimonK composite exhibit a high specific capacitance of 836 F g(-1) at a current density of 1 A g(-1), and excellent rate capability and cycling stability with capacitance retention of 92% after 5000 charge/discharge cycles.

Effect of Treatment Methods on Used Lubricating Oil for Recycling Purposes

The need to treat used lubricating oil for possible reuse has arisen due to concern for the environment, scarcity, price stability, and increasing dependence on this product for many industrial applications. Various methods, such as distillation/clay, acid/clay, acid, and activated charcoal/clay treatment methods, were employed in this study for the treatment of used Mobil and Total lubricating oil samples with the aim of improving their qualities for reuse. The characteristics of the fresh, used, and treated oil are tested for water content, specific gravity, kinematic viscosity, viscosity index, flash point, pour point, sulphur content, and concentrations of heavy metals (aluminum, iron, and lead). The results obtained showed that the usage of the lubricant oil affects the qualities of oil, for instance the sulphur of both brands of the oil samples was below the detectable limit, while the sulphur contents of the used oil are 0.80 and 0.69% for the used Mobil and Total oil samples, respectively. The results also revealed that treatments employed in this work were able to improve the characteristics of the used oil samples after treatment. The analyses of the results showed that the acid/clay method was the most effective method of treatment that brings the characteristics of the treated oil close to the fresh oil sample, while the distillation/clay and activated/charcoal methods were the best in terms of recovery of the oil after treatment. These two methods also recovered about 80% of the used lube oil samples compared to acid and acid/clay treatment methods, where the oil recovered was about 50% of the charge used oil sample.

Molecular weight and tacticity effect on morphological and mechanical properties of Ziegler–Natta catalyzed isotactic polypropylenes

The morphological and mechanical properties of Ziegler–Natta catalyzed isotactic polypropylenes as influenced by the molecular weight and tacticity was investigated. Polypropylene samples were injection moulded into standard disks with a HAAKE MiniJet II injection moulder at 190 °C and 200 bar for morphological and mechanical tests. The morphological and mechanical properties of specimens were investigated by means of optical microscope (OM), scanning electron microscopy (SEM), microhardness (MH) and dynamic mechanical analysis (DMA). The samples exhibited a typical α-modification spherulite structure of isotactic polypropylenes crystallized from the melt. It was found that the most important factor affecting the structure and properties of these polymers is the isotacticity content. A clear molecular weight effect was also found for samples with low molecular weights. The microhardness and storage modulus values increased as crystallinity did. Accordingly, isotacticity degree is considered as the main parameter affecting the crystallinity of samples.

Characterization of Two Nanofiltration Membranes for the Separation of Ions from Acid Mine Water

We evaluated nanofiltration for separation of ions from acid mine drainage (AMD), using two composite nanofiltration membranes (Nano-Pro-3012 and NF90) as examples of the polyamide class of acid-stable membranes. The structure of the NF membranes was characterized by scanning electron and atomic force microscopy. The NF90 displayed a higher permeate flux than Nano-Pro-3012, with higher relative roughness at both pH values. Both membranes suitably rejected most of the metals found in the AMD, but the Nano-Pro-3012 membrane proved unsuitable for sulphate removal.两种分离酸性矿山废水离子的纳米渗透膜用Nano-Pro-3012和NF90两种合成纳米膜作为酸稳定聚酰胺膜为例,评价了它们对酸性矿山废水(AMD)离子的分离效果。用扫描电镜和原子力显微镜观察NF膜结构。NF90膜比Nano-Pro-3012膜拥有更高渗透通量且在相同pH值条件下膜强度也更高。研究证明,两种膜都适于阻止酸性废水中多数金属离子通过,但Nano-Pro-3012膜更适于去除硫酸盐。ZusammenfassungWir bewerteten die Nanofiltration als Methode zur Abtrennung von Ionen aus saurem Grubenwasserunter Verwendung von zwei Komposit-Nanofiltrationsmembranen (Nano-Pro-3012 and NF90) als Beispiele für säurestabile Polyamid-Membranen. Die Struktur der Nanofiltrationsmembranen wurde durch Scanning-Elektronenmikroskopie und Atomkraftmikroskopie charakterisiert. NF90 zeigte einen höheren Permeatfluss als Nano-Pro-3012 mit höherer relativer Unschärfe bei beiden pH-Werten. Beide Membranen hielten hinreichend die meisten der im sauren Grubenwasser gefundenen Metalle zurück. Nano-Pro-3012 erwies sich allerdings als ungeeignet für die Rückhaltung von Sulfat.ResumenHemos evaluado la nanofiltración de iones de drenaje ácido de minas (AMD), usando 2 membranas de nanofiltración de composite (Nano-Pro-3012 y NF90) como ejemplos de membranas de poliamida resistentes a medio ácido. La estructura de las membranas NF fue caracterizada por microscopía electrónica de barrido y microscopía de fuerza atómica. La NF90 mostró un mayor flujo de permeación que Nano-Pro-3012, con mayor rugosidad relativa a ambos valores de pH. Ambas membranas rechazaron la mayoría de los metales presentes en el AMD, pero la membrana Nano-Pro-3012 mostró ser inadecuada para la remoción de sulfato.

The Realities and Economic Benefit of the Utilization of Fuel Cells as an Alternative Source of Energy: A Review

The 21st century has seen a critical need for alternative cleaner sources of energy and fuel cells are one of the technologies that have been developed to address the need. This article reviews the realities of fuel cell technologies as an alternative source of energy. It gives insight into the past, present, and future status of fuel cells as a way of addressing the energy crisis. It can be inferred from this article that the fuel cell industry continues to be constrained in its ability to commercialize the technology by a circular logic whereby it cannot generate significant commercial sales due to relatively high costs of units. It is imperative that this cycle be broken by converted actions of the fuel cell industry, the user community, and the governments. In spite of the challenges of commercialization, it was noted that fuel cells have been successfully delivering power to several prototypes and specialized applications in recent decades. The power output of a fuel cell stack is easily scalable to provide the right amount of electricity for a laptop computer, a small car, a city bus, or even utility generation and power building not connected to a national grid.

Polyolefins and the environment

Abstract Polymer science has built a considerable body of knowledge with regards to structure–property relationships. This knowledge starts with a thorough understanding of the primary structure of the polymer. Polymeric materials exhibit an extraordinary range of mechanical responses which depend on the chemical and physical structures of the polymer chains. Polymer degradation processes vary depending on the environmental conditions where the polymer is used during manufacturing and the structure of the polymer. Polymer degradation is usually shown by molecular weight variations due to the exposure to high processing temperature and to relevant mechanical stresses and strains. This chapter discusses the different types of polyolefins degradation, their methods and mechanism of degradation.

Effect of Synthesis Temperature on Particles Size and Morphology of Zirconium Oxide Nanoparticle

The paper presents the synthesis and investigation of zirconium oxide (ZrO2) nanoparticles that were synthesised by precipitation method with the effects of the temperatures of reaction on the particles size, morphology, crystallite sizes and stability at high temperature. The reaction temperature effect on the particle size, morphology, crystallite sizes and stabilized a higher temperature (tetragonal and cubic) phases was studied. Thermal decomposition, band structure and functional groups were analyzed by Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Thermo-gravimetric analysis (TGA) and Fourier transform infrared (FT-IR). The crystal structure was determined using X-ray diffraction. The morphology and the particle size were studied using (SEM) and (TEM). The shaped particles were confirmed through the SEM analysis. The transmission electron microscopic analysis confirmed the formation of the nanoparticles with the particle size. The FT-IR spectra showed the strong presence of ZrO2 nanoparticles.