Publications by authors named "Zeinhom M El-Bahy"

4 Publications

  • Page 1 of 1

Supercritical Carbon Dioxide Isolation of Cellulose Nanofibre and Enhancement Properties in Biopolymer Composites.

Molecules 2021 Aug 31;26(17). Epub 2021 Aug 31.

School of Industrial Technology, Universiti Sains Malaysia, George Town 11800, Penang, Malaysia.

The physical properties, such as the fibre dimension and crystallinity, of cellulose nanofibre (CNF) are significant to its functional reinforcement ability in composites. This study used supercritical carbon dioxide as a fibre bundle defibrillation pretreatment for the isolation of CNF from bamboo, in order to enhance its physical properties. The isolated CNF was characterised through zeta potential, TEM, XRD, and FT-IR analysis. Commercial CNF was used as a reference to evaluate the effectiveness of the method. The physical, mechanical, thermal, and wettability properties of the bamboo and commercial CNF-reinforced PLA/chitin were also analysed. The TEM and FT-IR results showed the successful isolation of CNF from bamboo using this method, with good colloidal stability shown by the zeta potential results. The properties of the isolated bamboo CNF were similar to the commercial type. However, the fibre diameter distribution and the crystallinity index significantly differed between the bamboo and the commercial CNF. The bamboo CNF had a smaller fibre size and a higher crystallinity index than the commercial CNF. The results from the CNF-reinforced biocomposite showed that the physical, mechanical, thermal, and wettability properties were significantly different due to the variations in their fibre sizes and crystallinity indices. The properties of bamboo CNF biocomposites were significantly better than those of commercial CNF biocomposites. This indicates that the physical properties (fibre size and crystallinity) of an isolated CNF significantly affect its reinforcement ability in biocomposites. The physical properties of isolated CNFs are partly dependent on their source and production method, among other factors. These composites can be used for various industrial applications, including packaging.
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http://dx.doi.org/10.3390/molecules26175276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433886PMC
August 2021

Dielectric characterization and catalytic activity studies of nickel chloride doped carboxymethyl cellulose films.

Spectrochim Acta A Mol Biomol Spectrosc 2012 Jun 18;92:105-12. Epub 2012 Feb 18.

Chemistry Department, Faculty of Science, Taif University, Taif, Saudi Arabia.

Cast technique was used to prepare films of sodium carboxymethyl cellulose (CMC) doped with different ratios of NiCl(2)·6H(2)O in the range of 0-40Ni(2+) wt.%. Thermal analysis (DTA) in the range of 25-600°C and dielectric properties in the temperature range of 30-150°C and frequency range of 0.1-100 kHz were measured for the prepared samples. DTA analysis showed new exothermic peaks which were attributed to structural phase transitions. Different molecular motions are separated via dielectric relaxation spectroscopy. In the high temperature range (higher than 100°C), the σ-relaxation, which is associated with the hopping motion of ions through polymer material, was detected. The detailed analysis of the results showed that the dielectric dispersion consists of both dipolar and interfacial polarization. Measurements of ac conductivity as a function of frequency at different temperatures indicated that the correlated barrier hopping model (CBH) is the most suitable mechanism for the ac conduction behavior. The catalytic activity of CMC doped with Ni(2+) was tested in the reduction of the hazardous pollutant 4-nitrophenol to the functional 4-aminophenol with an excess amount of NaBH(4). Ni-free CMC did not exhibit any catalytic activity for the studied reaction. However, Ni(2+)-doped CMC showed a significant catalytic activity that is proportional to the ratio of Ni(2+) included in CMC. The activation energy (E(a)) was estimated in the temperature range of 25-40°C. The estimated value of E(a) decreased with increasing the ratio of Ni(2+). Finally, the optimum catalyst mass was found to be ≈0.6 g/l.
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http://dx.doi.org/10.1016/j.saa.2012.02.043DOI Listing
June 2012

Enhancement of titania by doping rare earth for photodegradation of organic dye (Direct Blue).

J Hazard Mater 2009 Jul 18;166(1):138-43. Epub 2008 Nov 18.

Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo, Egypt.

Lanthanide ions (La(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), and Yb(3+))/doped TiO2 nanoparticles were successfully synthesized by sol-gel method. Their photocatalytic activities were evaluated using Direct Blue dye (DB53) as a decomposition objective. The structural features of TiO2 and lanthanide ions/TiO2 were investigated by XRD, SEM, UV-diffuse reflectance, and nitrogen adsorption measurements. Our findings indicated that XRD data characteristic anatase phase reflections and also XRD analysis showed that lanthanides phase was not observed on Lanthanide ions/TiO2. The results indicated that Gd(3+)/TiO2 has the lowest bandgap and particle size and also the highest surface area and pore volume (V(p)) as well. Lanthanide ions can enhance the photocatalytic activity of TiO2 to some extent as compared with pure TiO2 and it was found that Gd(3+)/TiO2 is the most effective photocatalyst. The photocatalytic tests indicate that at the optimum conditions; illumination time 40 min, pH approximately 4, 0.3g/L photocatalyst loading and 100 ppm DB53; the dye removal efficiency was 100%. Details of the synthesis procedure and results of the characterization studies of the produced lanthanide ions/TiO2 are presented in this paper.
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http://dx.doi.org/10.1016/j.jhazmat.2008.11.022DOI Listing
July 2009

Photo-degradation of acid green dye over Co-ZSM-5 catalysts prepared by incipient wetness impregnation technique.

J Hazard Mater 2008 May 28;153(1-2):364-71. Epub 2007 Aug 28.

Chemistry Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo, Egypt.

Co-ZSM-5 catalysts with different Co-loadings (2-30wt.%) were prepared by incipient wetness impregnation method. The prepared solid catalysts were characterized by X-ray diffraction, FTIR, in situ FTIR of pyridine adsorption and surface area measurements. The XRD data presented disintegration in the zeolitic crystalline structure accompanied by an increase in particle size of the prepared solids. New phases, Co(3)O(4) and Co(2)SiO(4), were detected with increasing the Co-loading, which indicate the strong interaction of cobalt ions with the ZSM-5 zeolite. FTIR study proved the presence of Co ions in stabilized sites inside the ZSM-5 framework. The in situ FTIR of adsorbed pyridine determined the type and relative strength of acidity on the surface of the prepared solids. The acidity switched from B-acid sites to L-acid sites with impregnation of cobalt ions in ZSM-5 zeolite. The acidity decreased with increasing Co-loading, which might be due to the destruction of zeolite framework and presence of new phases such as cobalt silicate and cobalt oxide on the surface. The surface texture characteristics changed with the promotion of ZSM-5 by cobalt ions, since a decrease of surface area, mean pore radius and pore volume was observed. The assessment of the catalytic activity was performed by the use of the photo-degradation of acid green (AG) dye as a probe reaction in presence of H(2)O(2) as an oxidant. The pH value controlled the degradation rate since a gradual increase of AG degradation rate was observed with increasing pH value and the optimum H(2)O(2) concentration was 61.6 mmol/l. It was found that, the AG degradation rate increased until an optimum value of Co-loading (ca. 10 wt.%), beyond which a monotonic decrease of reaction rate was recognized. The experimental data pointed to the importance of both the cobalt moieties and the zeolite framework structure in the AG degradation reaction.
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http://dx.doi.org/10.1016/j.jhazmat.2007.08.060DOI Listing
May 2008
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