Waheed A Al-Masry

Chemical Engineering

24.92

Publications

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    ABSTRACT: Diethylenetriamine (DETA) grafted polyacrylonitrile ((PAN) DETA-g-PAN) nanofibers (NFs) membrane was prepared by using electrospinning and chemical grafting techniques. Grafting of DETA to PAN was confirmed by Fourier Transforms Infrared (FT-IR) spectroscopy. Adsorption kinetics of methylene blue (MB), rhodamine B (RB), and safranin T(ST) dyes onto PAN and DETA-g-PAN NFs membranes showed that adsorption leveled off at ~ 60 min. The kinetics data showed good fitting to pseudo second order model. No change in the intra-particle diffusion pattern was observed for DETA-g-PAN membrane. The equilibrium adsorption data fitted well to Langmuir and Freundlich equations. The correlation coefficient (r2) varied from 0.940-0.995 for Langmuir and 0.941 to 0.999 for Freundlich equation. The maximum adsorption capacities (qmax) of dyes were increased in the order; MB (42.66 mg/g for PAN and 184.84 mg/g for DETA-g-PAN) < ST (72.46 mg/g for PAN and 195.7 mg/g for DETA-g-PAN) < RB (99.31mg/g for PAN and 367.65 mg/g for DETA-g-PAN). These values are far higher than the values reported in literature.
    Science of Advanced Materials 02/2015; 7(2):309-318. DOI:10.1166/sam.2015.2023 · 2.91 Impact Factor
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    ABSTRACT: Abstract EDA-g-PAN NFs membrane was prepared via electrospinning and chemical grafting techniques. Grafting (64%) with no change in the physical nature and colour was confirmed by FT-IR spectra. Adsorption kinetics of methylene blue (MB), rhodamine B (RB) and safranin T (ST) dyes onto PAN and EDA-g-PAN NFs membranes showed equilibrium time of around ~60 min. The adsorption kinetic followed pseudo-second-order model and intraparticle diffusion was not the only rate-limiting step. The adsorption data for the dyes fitted well to Langmuir and Freundlich equations. The order of adsorption capacity (qmax) obtained from Langmuir plot was: MB (94.07 mg/g) < ST (110.62 mg/g) < RB (138.69 mg/g). These values are more than most of the values reported in literature.
    Desalination and water treatment 06/2014; DOI:10.1080/19443994.2014.926840 · 0.99 Impact Factor
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    ABSTRACT: Oxime grafted polyacrylonitrile (OX-g-PAN) nanofibers (NFs) membrane was prepared by combining electrospinning and chemical grafting techniques. The membrane was extensively characterized with field emission scanning electron microscopy (FE-SEM) and Fourier transforms infrared (FT-IR) spectroscopy. High percent grafting (79 %) with no change in the physical nature was confirmed by FT-IR spectra. The adsorption kinetics of methylene blue (MB), rhodamine B (RB) and safranin T (ST) onto OX-g-PAN NFs membranes followed a pseudo-second-order model and no change in the intraparticle diffusion pattern was observed. The order of adsorption capacity ((qmax) at equilibrium time) was; MB (102.15 mg/g) r 2 values and varied from 0.950 to 0.985 and Freundlich (r 2 values varied from 0.988 to 0.996) equations. The increased adsorption by OX-g-PAN NFs membrane could be attributed to the increased exposed surface and number of active sites on the membranes. The good fitting to adsorption equations showed that beside condensation (physical adsorption) monolayer adsorption has also occurred. The adsorption capacity values of the present system were higher as compared to the values reported in the literature for conventional adsorbents.
    Journal of Polymer Research 03/2014; 21(3). DOI:10.1007/s10965-014-0371-1 · 1.90 Impact Factor
  • Journal of Polymer Research 04/2013; 20(4):1-11. · 1.90 Impact Factor
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    ABSTRACT: Random and highly aligned bead-free chitosan nanofibers (NFs) were successfully prepared via electrospinning by keeping the applied voltage (22 kV), flow rate (0.4 mL h−1), needle diameter (0.8 mm), and needle to collector distance (100 mm) constant while varying the solution concentration and collector rotation speed. No electrospinning was observed for lower solution concentrations, i.e., 1–3 wt% (w/v), whereas a decrease in the number and size of beads and microspheres, and bead-free NFs were obtained when the concentration of solution was increased from 4 to 6 wt%. Increase in the polymer concentration increased the solution viscosity (from 3.53 to 243 mPa s) and conductivity (from 29.80 to 192.00 μs cm−1) to critical values, which led to beadless NFs. The optimized conditions (i.e., concentration of solution 6 wt%, applied electrical potential 22 kV, flow rate 0.4 mL h−1, needle diameter 0.8 mm, and needle to collector distance 100 mm) were further used for the alignment of chitosan NFs. The alignment of the NFs increased from 35.6 to 94.4 % and the diameter decreased from 163.9 to 137.4 nm as the rotation speed of the cylindrical collector drum was increased from 2.09 to 21.98 m s−1. The aligned and small diameter chitosan NFs might find potential applications in biomedical, environmental, solar fuel cell applications, etc. Several target devices and polymer systems in the literature have been used to obtain aligned NFs; however, almost no work has been reported on individual chitosan alignment.
    Journal of Polymer Research 04/2013; -(-):-. DOI:10.1007/s10965-013-0105-9 · 1.90 Impact Factor
  • Muhammad Imran, Sajjad Haider, Asif Mahmood, Waheed A. Al-masry
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    ABSTRACT: Nanometer (nm) scale 1D zinc oxide (ZnO) nanofibers were fabricated through sol-gel processing and electrospinning of PVA and zinc acetate precursors. The structure and morphologies of the zinc acetate/PVA precursor and ZnO nanofibers were studied by fourier transform infrared (FTIR), X-ray diffraction, thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FE-SEM). Bead free smooth nanofibers with increased average diameters (278 nm (5wt%) and 423 nm (15wt%)) were obtained as the content of zinc acetate precursor was increased. The calcinations temperature of 480 °C was determined from TGA. FTIR, X-ray diffraction and TGA studies carried out after calcinations, confirmed the formation of ZnO nanofibers by the appearance of a band at 472 cm-1, characteristic ZnO pattern (i.e peaks at ∼ 31.820, 34.331, 36.496, 47.569 and 57.168 2θ degree) and no weight loss after 480oC, respectively. The burning of polymer has also been confirmed by the significant decrease in average diameter (124 nm (5wt%) and 197 nm (15wt%)) of the ZnO nanofibers. Electrospinning has been found a simple and cost effective technique for the synthesis of ID ZnO nanofibers mat for potential applications in the renewable energy devices.
    Arabian Journal of Chemistry 02/2013; 93. DOI:10.1016/j.arabjc.2013.01.013 · 2.68 Impact Factor
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    ABSTRACT: Chemical recycling of post-consumer poly(ethylene terephthalate) (PET) into useful feedstock was carried out in the presence of novel mesoporous metal oxide spinel catalysts. ZnO (hexagonal), metal oxide spinels (Co3O4 and Mn3O4), and mixed metal oxide spinel (ZnMn2O4, CoMn2O4, and ZnCo2O4) catalysts were synthesised via the precipitation or co-precipitation method. The structural, textural, and acidity properties of the materials were examined using various characterisation tools, such as XRD, SEM/EDX, TEM, FT-IR, NH3-TPD, and BET surface area analyser. The depolymerisation of waste PET (mostly soft-drink bottles) to the monomer bis(2- hydroxyethyl) terephthalate (BHET) via glycolysis was performed using excess ethylene glycol (EG) in the presence of fabricated metal oxides as transesterification catalysts. The effect of different parameters, such as temperature, catalyst type, reaction time, EG/PET molar ratio, and catalyst/PET weight ratio, on the monomer yield were investigated. The results revealed that the catalyst that yielded the highest amount of BHET (92.2 mol%) under mild reaction conditions (260 ºC and 5.0 atm) was zinc manganite tetragonal spinel (ZnMn2O4), which has tetrahedral Zn+2 ion and octahedral Mn+3 ion coordination with the spinel crystal structure. The high catalytic activity of this spinel may be attributed to its greater surface area, the presence of mild and strong acid sites, and its overall higher concentration of acid sites. Furthermore, the ZnMn2O4 structural properties were examined, and it was determined that the Zn+2/Mn+3 metal cations pair their positioning in the crystal structure and that the spinel geometry has a pronounced effect on the catalytic efficiency. The monomer, dimer, and oligomers were separated and characterised by thermal (DSC and TGA) and structural (NMR) analyses, which confirmed the purity and structure of the monomer and dimer. Based on the experimental observations, a reaction mechanism was also proposed. In conclusion, the present approach was an attempt to demonstrate a process consisting of a set of new catalysts with optimised process conditions for the maximum production of highly pure BHET.
    Polymer Degradation and Stability 01/2013; 98(4):904-915. DOI:10.1016/j.polymdegradstab.2013.01.007 · 2.63 Impact Factor
  • Edited by Dr. Mu. Naushad, 01/2013; Nova Science Publisher., ISBN: 978-1-62417-887-0
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    ABSTRACT: With contributions of research groups around the world in the last decade, the electrospinning process and its setup has made incredible progress. This technique is now capable of processing a variety of materials (such as organic polymers, composites and ceramics, etc.) not only into fibers with ultra fine diameters, but also to align and form core shell and hollow fibers as well. Therefore, it is not a surprise to many researchers that it has already found applications in many areas such as environmental engineering, biotechnology, defense, energy generation, etc. The electrospun membrane in particular may find great success in water treatment and biotechnology, where the removal of toxic materials and immobilization of cells needs high-surface area materials. In addition to high surface area, the changes in the surface chemistry of the nanofibers may also do wonders to their performance. This chapter presents an overview of the history and mechanism of electrospinning, various methods used for the nanofiber surface modification and the effectiveness of the modified nanofibers in the removal of hazardous material from waste water.
    A Book on Ion Exchange, Adsorption and Solvent Extraction, Chemistry Research and Applications edited by Mu Naushad and Zeid A. Al-Othman, 01/2013: chapter Electrospun Nanofibers and their Functionalization: pages 75-92; Nova Publishers., ISBN: 978-1-62417-887-0
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    ABSTRACT: Abstract Research work on the synthesis, designing and characterization of nanostructures has been extensively documented in the last decades. This in-depth documentation not only enabled researchers to understand the relationship between the nanostructure properties, size, shape, and composition but also have given them immense control over their manufacturing. This enhanced knowledge, cemented the switching of academic nanotechnology research into industrial products. However; despite the recent accomplishment in synthesis, characterization and application of the nanostructure materials, a complete knowledge/information of their interactions with biological systems is still not available. Hence, it is difficult to forecast the injurious biological responses of these novel nanostructures to humans, animals, insects and plants. Due to this hesitancy, safety regulatory authorities and general public have raised their concerns to the manufacturing and use of nanostructure-based products. Consequently, it is vital for the researchers to concentrate more on safe designing, manufacturing and characterization of nanostructures before these could meet human and communal needs. This review is taking an overview of the increasing investments in nanotechnology, designing, synthesis and characterization of nanostructures and their in vitro and in vivo toxicities. Keywords Carbonaceous NPs; Metal oxide NPs; Toxicity; In vitro; In vivo; NP synthesis
    Arabian Journal of Chemistry 10/2012; 28. DOI:10.1016/j.arabjc.2012.09.010 · 2.68 Impact Factor
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    Advanced Science Letters 10/2012; 17(1):217-223. DOI:10.1166/asl.2012.3679 · 1.25 Impact Factor
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    Material Recycling - Trends and Perspectives, 03/2012; , ISBN: 978-953-51-0327-1
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    ABSTRACT: A photocatalyst is provided that comprises activated carbon produced from date pits, impregnated with TiO2. The activated carbon can have a porous surface that can attract and trap pollutants flowing in air or water. The photocatalyst can be made by a method that includes preparing activated carbon by calcining date pits to form a precursor material, and then impregnating the precursor material with titanium dioxide.
    Ref. No: US13350952, Year: 01/2012
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    ABSTRACT: Effects of design parameters on pressure drop across the wire mesh mist eliminators were experimentally investigated in 15cm bubble column. The pressure drop across the demister pad was evaluated as a function of wide ranges of operating and design parameters. These parameters include: specific surface area (236–868m2/m3), void fraction (97–99%), wire diameter (0.14–0.28mm), packing density (130–240kg/m3), and superficial gas velocity (0.109–0.118m/s). All demisters were 15cm in diameter with 10cm pad thickness, made from 316L stainless steel layered type. Experiments were carried out using air–water system at ambient temperature and atmospheric pressure. The measurements of the pressure drop were done using a U-tube manometer device. The pressure drop across the demister pad is a combination of dry and wet pressure drops. In this work, the experimental investigations showed that the dry pressure drop is nil. The wet pressure drop was found to increase with increasing the demister specific surface area, packing density, and superficial gas velocity. In contrast, it was found to increase with decreasing the demister void fraction and wire diameter. The pressure drop is correlated empirically as a function of the design parameters. A good agreement was obtained between the measured values and the correlation predictions with ±15% accuracy.
    Journal of Saudi Chemical Society 01/2011; 15(1):1-9. DOI:10.1016/j.jscs.2010.09.008 · 1.29 Impact Factor
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    ABSTRACT: The adsorption phenomenon of bromo-phenol blue onto pristine and thermally evacuated granular charcoal (GC) was studied via a batch technique at 25 °C. The effect of evacuation temperature on the GC surface and pore structure (e.g. pore volume and diameter) was studied by Fourier transform infrared spectroscopy (FT-IR), point of zero charge (PZC), proximate analysis, Brunauer, Emmett and Teller (BET) method and field emission scanning electron microscopy (FE-SEM). The FT-IR spectra of the samples after evacuation showed considerable decrease in the acidic functional groups. PZC showed that the surface of the evacuated charcoal became basic as the evacuation temperature was increased from 300 to 800 °C. Volatile matter decreased while ash and fixed carbon contents increased during evacuation, which led to an increase in the micro-pore volume from 0.25 to 0.42 cm3 g−1, meso-pore volume from 0.04 to 0.13 cm3 g−1, pore diameter from 5.01 to 6.21 nm, and specific surface from 150.32 to 254.70 m2 g−1. Adsorption of the bromo-phenol blue onto charcoal, increased as the evacuation temperature was increased from 300 to 800 °C. The interaction of bromo-phenol blue with charcoal was proposed to have occurred via hydrogen bonding. The adsorption data fitted well with the Langmuir equation, which indicated that the monolayer adsorption has occurred at specific sites within the adsorbent.
    Chemical Engineering Research and Design 01/2011; 28(1-0263-8762):23-28.-1.968 Impactor Factor. DOI:10.1016/j.cherd.2010.04.022, · 2.28 Impact Factor
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    ABSTRACT: Effects of design parameters on performance of wire-mesh mist eliminators were experimentally investigated in 15cm bubble column. The demisters performances were evaluated by droplet collection efficiency as a function of wide ranges of operating and design parameters. These parameters include: droplet size exiting the demister (250–380μm), specific surface area (236–868m2/m3), void fraction (97–98.3%), wire diameter (0.14–0.28mm), packing density (130–240kg/m3), and superficial gas velocity (0.109–0.118m/s. All demisters were 15cm in diameter with 10cm pad thickness, made from 316L stainless steel layered type demister pad wires. Experiments were carried out using air–water system at ambient temperature and atmospheric pressure. The experimental data on the droplet removal efficiency were obtained using Malvern Laser Droplet Sizer. The removal efficiency was found to increase with the increasing the demister specific surface area, packing density, and superficial gas velocity. In contrast, the removal efficiency was found to increase with decreasing the demister void fraction and wire diameter. The separation efficiency is correlated empirically as a function of the design parameters. A good agreement was obtained between the measured values and the correlation predictions with ±5% accuracy.
    Journal of Saudi Chemical Society 10/2010; 14(4):331-339. DOI:10.1016/j.jscs.2010.04.001 · 1.29 Impact Factor
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    ABSTRACT: A functional nanofiber membrane can remove copper and lead ions from aqueous solution better than conventional membrane and polymer beads.
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    ABSTRACT: This paper deals with application of non-invasive electrical capacitance tomography to study the hydrodynamics of shallow bed bubble columns. Two bubble columns with different height to diameter ratio were used. Air–kerosene system that represents dielectric two-phase mixture was investigated. The ECT provided good measurement of the gas holdup at different gas velocities compared to the classical pressure measurements. The ECT was able to provide the gas hold up and the bubble velocities distribution across the column diameter at different gas velocities. The study revealed that spatial gas holdup and bubble velocity distributions are sharp with parabolic shape in the small bubble column (H D /D C = 5). However, in the large bubble column (H D / D C = 4) the gas holdup and bubble velocity profiles were flatter indicating improvement in the mix-ing homogeneity and leading to well-mixed reactor. 3D graphical visualization of the flow regimes and transition points were also examined using the ECT. In the small bubble column flow regimes were heterogeneous to slugs flow especially at high flow rate, resulted in downward flow near the walls and imperfect mixing.
    Journal of Saudi Chemical Society 03/2010; 14(3). DOI:10.1016/j.jscs.2010.02.022 · 1.29 Impact Factor
  • A. Ajbar, W. Al-Masry, E. Ali
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    ABSTRACT: Passive acoustic sound, measured by a hydrophone in an air–water bubble column, is used to study the hydrodynamics of the unit. The recorded measurements taken at different superficial gas velocities are processed using both spectral and chaos-based techniques in order to characterize the column flow regimes and to predict the transitions points. These processing tools were supported by digital video imaging of bubbles motion inside the column. The results of data analysis indicate the applicability of passive sound measurements to identify flow regimes in the bubble column. In this regard the analysis of sound spectra gives a useful qualitative comparison of flow regimes. Chaos-based techniques, on the other hand, are more successful in predicting the transition points between the homogenous and the churn-turbulent flow regimes in the column. The critical gas velocities of the transition are associated with a marked change in some of the calculated chaotic invariants of sound pressures. The calculated superficial gas velocities of the critical points are also found to be consistent with experimental observations. Moreover, a useful visualization of the dynamics induced in the column by the alternation of small and large bubbles is possible through the inspection of phase-space trajectories reconstructed from time-series measurements. The shape and size of the trajectories are closely linked to the size distribution of bubbles, and they change as the flow moves from one regime to an other.
    Chemical Engineering and Processing 01/2009; 48(1-48):101-110. DOI:10.1016/j.cep.2008.02.004 · 1.96 Impact Factor
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    ABSTRACT: Gas holdups were measured in a circulating bubble column (CBC) using air-water system with various additives. The liquid volume in the gas separator affected downcomer gas holdup up to volume ratio equal to 6%. Presence of surface active agents, alcohols, solid particles had little effects on the gas holdups ϵgd — aϵgr relationships. The gas holdups relationships are theoretically related by a single parameter model ϵgd = aϵgr — a + 1, and empirically by two parameter model ϵgd = aϵgr — constant. The theoretical model yielded a values 0.45, while the empirical model yielded a values 1.16. Analogy between the two models (Contreras et al., 1998) will lead to incorrect conclusions.Des rétentions de gaz ont été mesurées en CBC à l'aide d'un système air-eau et divers additifs. Le volume de liquide dans le séparateur de gaz a une influence sur la rétention de gaz de la colonne descendante jusqu'à un rapport de volume égal à 6%. La présence d'agents de surface actifs, d'alcools et de particules solides a peu d'effets sur les relations ϵgd — aϵgr des rétentions de gaz. Les relations des rétentions de gaz sont théoriquement reliées par un modèle à paramètre unique ϵgd = aϵgr — a + 1, et empiriquement par un modèle à deux paramètres ϵgd = aϵgr — constante. Le modèle théorique donne des valeurs de a 0,45, alors que le modèle empirique donne des valeurs de a 1,16. Une analogie entre les deux modèles (Contreras et al, 1998) conduira à des conclusions incorrectes.
    The Canadian Journal of Chemical Engineering 06/2008; 82(3):607 - 612. DOI:10.1002/cjce.5450820321 · 1.31 Impact Factor

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