Nasser Mostafa
Suez Canal University, Chemistry, Faculty Member
The impact of a high molecule organic compound containing amine fragment (HMoA) on the corrosion and electrochemical behaviors of carbon steel (CSA516), ferritic (SS410) and austenitic (SS304L) stainless steels was studied in the... more
The impact of a high molecule organic compound containing amine fragment (HMoA) on the corrosion and electrochemical behaviors of carbon steel (CSA516), ferritic (SS410) and austenitic (SS304L) stainless steels was studied in the environment of the LAO (linear α-olefin) plant. Corrosion tests were carried out at 270 oC and 29 bar in an autoclave at different exposure time intervals (up to 30 days). Corrosion rates were determined using mass losses of the samples with and without HMoA. Optical microscopy (OM) and scanning electron microscopy (SEM) were employed to assess the morphologies of the corroded and inhibited surfaces. Efficiency and kinetics of electrode processes in the presence of HMoA were investigated by means of polarization and impedance measurements. Results of these experimental data are widely presented and discussed in this paper. It was found that the inhibition performance of the tested compound recorded inhibition efficiencies of 30%, 66% and 95% for CSA516, SS4...
ABSTRACT A series of Zn1–xNixFe2O4 nano ferrite (with x=0, 0.2, 0.4, 0.6, 0.8, and 1) compositions were synthesized using the combustion technique. The powder samples were characterized by XRD. The X-ray analysis showed that the samples... more
ABSTRACT A series of Zn1–xNixFe2O4 nano ferrite (with x=0, 0.2, 0.4, 0.6, 0.8, and 1) compositions were synthesized using the combustion technique. The powder samples were characterized by XRD. The X-ray analysis showed that the samples were single phase spinel cubic structure. The AC resistivity decreases by increasing the frequency from 1 kHz to 10 kHz. As the frequency of the applied field increases the hopping of charge carrier also increase, thereby decreasing the resistivity. A shift in dielectric maximum is observed toward higher temperature with increasing the Ni content from 536 K to 560 K at 1 kHz. The HRTEM (high resolution TEM) images of four compositions have lattice spacing which confirms the crystalline nature of the samples. The surface morphology SEM of the sample consists of some grains with relatively homogenies distribution with an average size varying from 0.85 to 0.92 μm. The values for entropy change in this work are still small but are significally higher than the values that have been reported for iron oxide nanoparticle. The magnetic entropy change was calculated from measurements of M (H, T) where H is the magnetic field and T is the temperature. The maximum value of entropy change (∆S) obtained near Curie temperature which makes these material candidates for magnetocaloric applications.
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Research Interests: Nanoparticles and TEM
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Abstract: Traditionally, granite is used to produce porcelain and stoneware in Saudi Arab. In the present investigation, the granite raw materials were collected from Taif area (Wade Elnoman). The nature granite was characterized with... more
Abstract: Traditionally, granite is used to produce porcelain and stoneware in Saudi Arab. In the present investigation, the granite raw materials were collected from Taif area (Wade Elnoman). The nature granite was characterized with respect to their mineralogical ...
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During initial days of α-SABLIN (LAO,s) commercial plant operation, general corrosion was observed in the downstream separation columns. This was due to traces of catalyst not being completely neutralized thus forming acidic medium... more
During initial days of α-SABLIN (LAO,s) commercial plant operation, general corrosion was observed in the downstream separation columns. This was due to traces of catalyst not being completely neutralized thus forming acidic medium (mainly hydrochloric), resulting in the corrosion of the columns. In this respect the high temperature corrosion behavior of three important steel materials, namely carbon steel (CSA516) and ferritic (SS410) and austenitic (SS304L) stainless steels was studied by mass loss method at the process conditions and environment of the α-SABLIN (LAO,s) commercial plant. Measurements were conducted at 270 oC and 29 bar as a function of immersion time (up to 30 days). Such measurements are complemented with X-ray diffraction (XRD), optical microscope (OM) and scanning electron microscopy (SEM). The obtained findings revealed that the three tested steel samples corrode in the environment of the α -SABLIN (LAO,s) commercial plant. The corrosion rate varies depending ...
Water-cooled slag (WS) and air-cooled slag (AS) were characterized chemically and mineralogically and a comparative study of their reactivities with 10% and 20% lime was conducted using an accelerated chemical method. Both types of slag... more
Water-cooled slag (WS) and air-cooled slag (AS) were characterized chemically and mineralogically and a comparative study of their reactivities with 10% and 20% lime was conducted using an accelerated chemical method. Both types of slag have the same chemical composition, but WS is completely vitreous materials and the main mineral composition of AS is gehlenite. The kinetics of the WS–lime and AS–lime reactions were investigated in suspension by the determination of the proportions of unreacted lime and the combined water up to 28 days. Both slags underwent hydration at room temperature. The rates of hydration were rapid in the first 3 days, but subsequently it depressed due to the formation of dense layer of hydration products on the unhydrated slag grains. The hydration products were identified by X-ray diffraction (XRD) and SEM combined with EDX. The hydration products formed depend on the lime contents. The results obtained suggest that AS may be used in the production of low strength building units or may be used with WS in the production of slag cement.
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Single phases calcium silicate hydrates (1.1 nm tobermorite; Ca5Si6O16(OH)2·4H2O), with Fe3+ and Mg2+ substitutions, were synthesized under hydrothermal conditions at 175 °C. The structure of different tobermorite samples was investigated... more
Single phases calcium silicate hydrates (1.1 nm tobermorite; Ca5Si6O16(OH)2·4H2O), with Fe3+ and Mg2+ substitutions, were synthesized under hydrothermal conditions at 175 °C. The structure of different tobermorite samples was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The results indicated that Fe and Mg ions played a key role in crystallization, morphology and structure of tobermorite. Mg2+ increases crystallinity of tobermorite and changes its morphology from platy-shape at 4 h curing time to lamellar-shape at longer curing time. Fe3+ increases imperfection of tobermerite at short curing time, however it increases crystallinity at longer curing time and the morphology of tobermorite changes magnificently from reticulated-shape to fiber-shape. FTIR proved that Fe+ and Mg+ increase silicate chains polymerization and increase the chain cross-linkage, which is consistent with tobermorite lamellar and fibers morphology that grow parallel to the b-axis (along the silicate chains). The cations exchange capacity (CEC) of Fe- and Mg-substituted tobermorites is lower than that of the unsubstituted tobermorite. Cross-linkage in the silicate chains was found to cause a reduction in cation exchange capacity.
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Commercial low-cost laser induced breakdown spectroscopy (LIBS) has been successfully employed for the quantitative analysis of a Cu-based alloy using a Nd:YAG laser at 1064 nm. The main aim of the present investigation is to explore the... more
Commercial low-cost laser induced breakdown spectroscopy (LIBS) has been successfully employed for the quantitative analysis of a Cu-based alloy using a Nd:YAG laser at 1064 nm. The main aim of the present investigation is to explore the benefits of a commercial low-cost LIBS setup. It was recognized that some trace elements such as Al and S could not be detected by LIBS even with a high-resolution spectrometer. The main difficulties in quantifying Cu as a basic component of a brass alloy are related to the self-absorption of Cu spectral lines, with the effect complicated at Cu concentrations higher than 65%. However, few Cu lines such as that at 330.795 nm would be helpful to use due to their lower susceptibility to self-absorption. LIBS, flame atomic absorption spectrometry (FAAS), and wavelength dispersive X-ray fluorescence (WDXRF) were compared for the detection of major and trace metals in the Cu-based alloy. In the case of WDXRF, the brass samples were identified by using a standardless quantitative analysis program depending on a fundamental parameter approach. The quantitative analysis results were acceptable for most of the major and minor elements of the brass sample. Therefore, commercial low cost LIBS would be useful for quantitative analysis of most elements in different types of alloys.
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Substitutions of sulfate and aluminum ions in calcium silicate hydrate (tobermorite) were investigated at 175 °C under saturated steam pressure. Structure and morphology of different tobermorite samples were investigated using XRD, FTIR... more
Substitutions of sulfate and aluminum ions in calcium silicate hydrate (tobermorite) were investigated at 175 °C under saturated steam pressure. Structure and morphology of different tobermorite samples were investigated using XRD, FTIR and SEM. A sample of pure xonotlite was prepared to assist in FTIR band assignment of different tobermorites. Al3+ decreases the degree of crystallinity at short curing time and increases crystallinity at longer curing times, with a sort of stabilization of small crystals. Al3+ changes the morphology of tobermorite from platy-shape to lath-shape. Sulfate ion increases imperfection of tobermorite crystal structure and the morphology of tobermorite change magnificently to leafy shape. The FTIR spectra of all 1.1 nm tobermorite samples are nearly similar. All tobermorite samples have a significant concentration of Q3 Si sites, which indicates cross-linking of the chains. Sulfate substitution for silicate in tobermorite structure is associated with the appearance of the bands at 1610 and 631 cm−1 which indicates the incorporation of CaO–H group in tobermorite structure. This indicated the charge compensation mechanism; SiO44− is substituted by SO42− and 2OH−.
Research Interests: Engineering, Materials Engineering, Condensed Matter Physics, Inorganic Chemistry, Materials Chemistry, and 16 moreCrystal Growth, Chemical, Solid State Chemistry, Advanced Materials, Multidisciplinary, Physical sciences, Hydrogen Bond, CHEMICAL SCIENCES, X ray diffraction, Particle Size, Single Crystal, Hydrothermal Synthesis, IR Spectroscopy, Three Dimensional, Solid State Electrolyte, and Layered Architecture
Cobalt ferrite nanoparticles were prepared via thermal treatment of cobalt–iron mixed hydroxides at 400–600 °C. The mixed hydroxides were coprecipitated from their nitrates solutions using NaOH as precipitating agent. The effects of pH... more
Cobalt ferrite nanoparticles were prepared via thermal treatment of cobalt–iron mixed hydroxides at 400–600 °C. The mixed hydroxides were coprecipitated from their nitrates solutions using NaOH as precipitating agent. The effects of pH and temperature of coprecipitation and calcination temperature on the physicochemical, surface and catalytic properties of the prepared ferrites were studied. The prepared systems were characterized using TG, DTG, DTA, chemical analysis, atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) as well as surface and texture properties based on nitrogen adsorption–desorption isotherms. The prepared cobalt ferrites were found to be mesoporous materials that have crystallite size ranges between 8 and 45 nm. The surface and catalytic properties of the produced ferrite phase were strongly dependent on coprecipitation conditions of the mixed hydroxides and on their calcination temperature.
Research Interests: Materials Engineering, Condensed Matter Physics, Nanoparticles, Porous Materials, Nitrogen, and 17 moreIron, Chemical Analysis, XRD, Specific surface area, Energy Dispersive X-Ray Analysis, Thermogravimetry, Crystallite Size, X ray diffraction, Thermal Treatment, Differential Thermal Analysis, Ferrites, Atomic Absorption Spectroscopy, Coprecipitation, EdX, Chemical Synthesis, Heat Treatments, and Surface Texture
Silica fume (SF) and dealuminated kaolin (DK) were investigated for their pozzolanic activities. The kinetics of the SF–lime and DK–lime reactions were investigated in pastes at room temperature, 100°C, and 180°C by the determination of... more
Silica fume (SF) and dealuminated kaolin (DK) were investigated for their pozzolanic activities. The kinetics of the SF–lime and DK–lime reactions were investigated in pastes at room temperature, 100°C, and 180°C by the determination of unreacted lime and combined water. The hydration products were identified by X-ray diffraction (XRD). The variations in mechanical properties were correlated with the reaction kinetics and the hydration products formed. DK exhibited higher reactivity than SF at all temperatures studied. Tobermorite was formed at 100°C in the high-lime DK mix at 14 days and extensively formed by autoclaving at 180°C curing due to the presence of Al and sulfate in the DK. The very low C/S ratios of SF mixes and low-lime DK mix prevent tobermorite formation and promote the formation of poorly crystalline C-S-H with a higher surface area.
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Silica fume (SF) and dealuminated kaolin (DK) from Egyptian sources have been characterized chemically and mineralogically, and a comparative study of their reactivities toward lime were conducted using isothermal conduction calorimetry... more
Silica fume (SF) and dealuminated kaolin (DK) from Egyptian sources have been characterized chemically and mineralogically, and a comparative study of their reactivities toward lime were conducted using isothermal conduction calorimetry and an accelerated chemical method. The kinetics of SF–lime and DK–lime reaction were investigated in suspension. Unreacted lime and combined water were determined as function of time, and the hydration products were identified with X-ray diffraction (XRD) and SEM combined with EDX. DK has a much higher surface area (90.5 m2/g) than SF (18.6 m2/g) and exhibits much higher pozzolanic activity, especially during early hydration. A low-density sponge-like CSH was formed, from both SF and DK at low lime contents (20% CH), and a more dense CSH was formed at higher lime contents (40% CH).
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Lime and sand in autoclaved aerated concrete (AAC) were replaced by air-cooled slag (AS). The compressive strength and the type and nature of the hydration products were studied for samples autoclaved at 8 bar for different periods of... more
Lime and sand in autoclaved aerated concrete (AAC) were replaced by air-cooled slag (AS). The compressive strength and the type and nature of the hydration products were studied for samples autoclaved at 8 bar for different periods of times: 2, 6, 12 and 24 h. The hydration reactions were monitored by determining free-lime contents and combined water. The types of the hydration products were investigated using XRD and SEM/EDX. Slag substitutions for sand and lime up to 50% enhance the compressive strength, especially at short curing times (2 and 6 h). The optimum strength is obtained by 50% AS substitution for low-lime mixes (10% CaO) and 30% AS substitution for high-lime mixes (25% CaO). In high-lime mixes containing up to 30% AS, the initially formed fibrous calcium-rich CSH was changed to needle-like and lath-like 1.1 nm tobermorite. In low-lime mixes with AS-substitution, tobermorite appears at 2 h processing time with grass-like silica-rich CSH around quartz particles.
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Sinterability and thermal stability of nanocrystalline hydroxyapatite powders with co-substituted sodium, silicate and carbonate ions have been investigated. The effect of powder characteristics on the thermal stability and... more
Sinterability and thermal stability of nanocrystalline hydroxyapatite powders with co-substituted sodium, silicate and carbonate ions have been investigated. The effect of powder characteristics on the thermal stability and physico-chemical properties of the produced ceramic bodies have been correlated. Thermal stability of hydroxyapatite depends on the amounts and nature of different substitutents. Substitution, of both sodium and carbonate ions, in hydroxyapatite increases the thermal stability and enhances the grain growth at relatively low sintering temperatures. In silicate containing hydroxyapatite the start of sintering and hence the sintering density and the mechanical properties depends on silicate contents. Substitution of silicate up to 2.23 wt% silicon on hydroxyapatite inhibited densification and decreased mechanical properties at temperatures within 900–1100 °C. As the level of silicate substitution was increased above 2.23 wt% Si of hydroxyapatite, the mechanical properties were improved regardless of the presence of a considerable amount of pores. This finding might be attributed to the formation of silicocarnotite (Ca5(PO4)2SiO4).
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A general ceramics processing scheme by cold uniaxial pressing and conventional sintering process have been used to prepare ceramics from mixtures of blast furnace slag (BFS) and kaolin (10%, 30% and 50% kaolin). The properties of the... more
A general ceramics processing scheme by cold uniaxial pressing and conventional sintering process have been used to prepare ceramics from mixtures of blast furnace slag (BFS) and kaolin (10%, 30% and 50% kaolin). The properties of the ceramics were studied by measuring linear shrinkage, bulk density, apparent porosity and mechanical properties of samples heated at temperatures from 800 °C to 1100 °C. The formed crystalline phases were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). Slag melt formed at relatively low temperatures (800–900 °C) modified the sintering process to liquid phase sintering mechanism. Combination of BFS with 10% kaolin gave the highest mechanical properties, densification and shrinkage at relatively low firing temperatures. The crystalline phases were identified as gehlenite (Ca2Al2SiO7) in both BFS and BFS with 10% kaolin samples. Anorthite (CaAl2Si2O8) phase increased with increasing kaolin contents. In the case of kaolin-rich mixtures (30% and 50% kaolin), increased expansion took place during firing at temperatures in the range 800–1000 °C. This effect could be attributed to the entrapment of released gases.
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A study comparing silica fume (SF) and dealuminated kaolin (DK) as pozzolanic materials was carried out. 10, 20 or 30-wt.% SF or DK were substituted for Portland cement. The kinetics of hydration were studied at water/solid ratios of 0.30... more
A study comparing silica fume (SF) and dealuminated kaolin (DK) as pozzolanic materials was carried out. 10, 20 or 30-wt.% SF or DK were substituted for Portland cement. The kinetics of hydration were studied at water/solid ratios of 0.30 and 0.50. The hydration reactions were monitored by determining the compressive strengths, the free lime contents and the amounts of combined water. The hydration products were investigated using XRD and SEM/EDX. Both pozzolans increase the total porosities, when used without water reducers or superplasticizers. Both also decreased the compressive strengths at early ages. However, the strengths recovered with time exceed that of the reference Portland cement paste. Strength gain was more rapid in DK mixes than in SF mixes. The optimum content of each pozzolan varied with the water/solid ratios of the blends. Unreacted silica fume, in the highly-substituted mix (30%), caused a reduction in the mechanical properties by providing weak points for the crack propagation.
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Water-cooled slag (WS) and air-cooled slag (AS) with similar chemical compositions and produced from the same blast furnace were investigated for their hydraulic activities at different temperatures. The kinetics of hydration of WS–lime... more
Water-cooled slag (WS) and air-cooled slag (AS) with similar chemical compositions and produced from the same blast furnace were investigated for their hydraulic activities at different temperatures. The kinetics of hydration of WS–lime and AS–lime pastes were investigated at room temperature, 100°C, and 180°C by the determination of unreacted lime and combined water. The hydration products were identified by XRD. The variations in mechanical properties were correlated with the reaction kinetics and the types of the hydration products. The change in the mechanism of slag hydration was also predicted. The AS studied exhibited significant reactivity at room temperature. Increasing the temperature to 100°C has no significant effect on the reactivity of either type of slag except during early hydration. However, the reactivity of AS increased much more than WS with hydrothermal activation at 180°C. Calcium silicate hydrate (CSH) and plazolite formed in AS mixes. CSH, plazolite, and α-C2SH formed in WS mixes at 180°C.
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A force field for the modeling of hydroxyapatite; Ca10(PO4)6OH2 (HAP) is established based upon transferable potentials. Ca–O, P–O and O–O potentials were transported from those previously published for fluorapatite and based on single... more
A force field for the modeling of hydroxyapatite; Ca10(PO4)6OH2 (HAP) is established based upon transferable potentials. Ca–O, P–O and O–O potentials were transported from those previously published for fluorapatite and based on single crystal experimental data. The interactions of hydroxyl oxygen with calcium and phosphate were re-scaled by fitting to experimental data for CaO and AlPO4, respectively, to account for the reduction in the oxygen charge from −2.0 to −1.426. Force field accuracy is tested by comparing the calculated and experimental values for the cell constant and atom positions in the unit cell. The elastic constants and bulk modulus calculated for HAP are in close agreement with the experimental results. The potentials were also used to calculate the compressibility data of HAP and fluorapatite, and these results also agree with the published experimental data. Using formal charges for metal cations allows modeling the complete solid solution of Cd–Ca hydroxyapatite with a good accuracy.
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A study was carried out comparing silica fume (SF) and dealuminated kaolin (DK) as pozzolanic materials in blended cements. Ten, 20 or 30 wt% of SF or DK were substituted for Portland cement. The kinetics of hydration up to 45 h were... more
A study was carried out comparing silica fume (SF) and dealuminated kaolin (DK) as pozzolanic materials in blended cements. Ten, 20 or 30 wt% of SF or DK were substituted for Portland cement. The kinetics of hydration up to 45 h were studied using isothermal conduction calorimetry. Blends containing pozzolanic materials usually have decreased heats of hydration compared to pure cement during the period of C3S hydration, i.e. during the main hydration peak. Depending on the chemical composition and the activity of the pozzolan, the reaction taking place with the lime typically contributes to the heat output after the main hydration peak.The pozzolanic activity of DK is the principal factor and heat evolution increases with respect to pure PC mortar, during the first 15 h. The presence of hydrated silica (silanol groups) in DK increases the pozzolanic activity especially before and during induction period. The acidic silanol sites are capable of a fast acid–base reaction with the alkalis and with any Ca(OH)2 present in cement during the induction period.
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Hydroxyapatite (HAP) powder precursors have been used as starting material for biomedical applications, such as synthetic bone graft materials and scaffold for hard tissue engineering. Considering the numerous applications of... more
Hydroxyapatite (HAP) powder precursors have been used as starting material for biomedical applications, such as synthetic bone graft materials and scaffold for hard tissue engineering. Considering the numerous applications of hydroxyapatite, three different routes for HAP powders preparations was investigated. Two powders were prepared by chemical precipitation reactions at 100 °C and one by mechanochemical reaction. The powders were characterized using chemical analysis, surface area measurements, laser diffraction, X-ray diffraction (XRD) and SEM. The Ca/P ratios were varied from 1.67 to 1.58. The chemical composition, the crystallinity and the agglomeration characters depend on the preparation route. The effect of powder characteristics on the sinterability was investigated. Although, the thermal stability and hence the start of sintering dependents on the Ca/P ratio, the final sintering density and hence the mechanical properties depends on the agglomeration characteristics and the particle size distribution. Hydroxyapatite powder prepared by mechanochemical route have nano-sized crystallites with a uniform smaller agglomerated particle size distribution and have a butter sinterability.