Z H Yamani

King Fahd University of Petroleum and Minerals, Az̧ Z̧ahrān, Eastern Province, Saudi Arabia

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Publications (53)66.99 Total impact

  • Catalysis Today 01/2014; 230:158–165. · 2.98 Impact Factor
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    ABSTRACT: We report structural and optical properties of Cu doped ZnO (ZnO:Cu) thin films deposited on glass substrate at room temperature by pulsed laser deposition (PLD) method without pre and post annealing contrary to all previous reports. For preparation of (ZnO:Cu) composites pure Zn and Cu targets in special geometrical arrangements were exposed to 248 nm radiations generated by KrF exciter laser. The laser energy was 200 mJ with 10 Hz frequency and 20 ns pulse width. The effect of Cu concentration on crystal structure, morphology, and optical properties were investigated by XRD, FESEM and photoluminescence spectrometer respectively. A systematic shift in ZnO (0 0 2) peak with Cu concentration observed in XRD spectra demonstrated that Cu ion has been incorporated in ZnO lattice. Uniform film with narrow size range grains were observed in FESEM images. The photoluminescence (PL) spectra measured at room temperature revealed a systematic red shift in ZnO emission peak and decrease in the band gap with the increase in Cu concentration. These results entail that PLD technique can be realized to deposit high quality crystalline ZnO and ZnO:Cu thin films without pre and post heat treatment which is normally practiced worldwide for such structures.
    Applied Surface Science 04/2013; 270:104–108. · 2.11 Impact Factor
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    ABSTRACT: The possibility of adsorption of a toxic H2S gas molecule on graphene is investigated using first principles methods. The long-range van der Waals (vdW) interactions are incorporated within the density functional theory (DFT) framework. Three different configurations of graphene: (a) pristine graphene, (b) graphene with defects, and (c) III-N-doped graphene have been studied. No adsorption of H2S molecule is observed in all the three cases. More specifically, in the cases (a) and (c), the molecule was found to be suspended at a distance of about 3.4 å from the surface of graphene with a binding energy of around -15.4 kJ/mol. Whereas, defects (in case b), such as Stone-Wales (SW) defects or vacancies, break the symmetry of graphene and introduce localized states near the Fermi level. The accumulation of charge at the defect sites introduces stronger electric dipole moments and consequently enhances the vdW interactions with the H2S molecule. For instance, it is observed in the case of SW defect that the H2S molecule gets closer to the surface of graphene (to about 2.86 å) with a much larger (˜9 times larger than the other two cases) binding energy of about -134 kJ/mol.
    Surface Science. 03/2013; 621:43003-.
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    ABSTRACT: The nucleation and growth of MTT zeolite, an important 10-membered ring (10 MR) zeolite, was controlled by a microwave-assisted hydrothermal synthesis. The effect of irradiation time (12,18, and 24 h), seed-assisted synthesis with 1 wt.% seeds for 6 h and desilication under microwave irradiation on crystallinity and porosity were investigated. Under microwave-assisted synthesis, uniform crystal size, with lower crystal aspect-ratio and suppressed phase-impurity has been obtained. The tendency of column-like crystal to form bundle of columns was reduced significantly. Seeded growth further reduced synthesis time to 6 h. Post-synthetic treatment was used to obtain larger pore volume of MTT zeolites. Some of the protonated MTT samples were tested in n-hexane cracking as model reaction. Characterization techniques such as XRD, FE-SEM, N2 adsorption–desorption, 27Al MAS NMR and NH3-TPD have been carried out to obtain insight in the physico-chemical properties of zeolite catalysts.
    Chemical Engineering Journal. 01/2013; 226:367-376.
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    ABSTRACT: The work presented here deals with the photoreduction in metallic silver nanoparticles onto the surface of Ag(3)PO(4) and resulting photocatalytic activity enhancement toward degradation of dye molecules, namely Rhodamine B (Rh. B) as a model compound, from aqueous solution under UV or visible light irradiation. Our results clearly indicated that the photoactivity of Ag(3)PO(4) was significantly enhanced by depositing an optimum amount of silver nanoparticles, even though the adsorption kinetics rate and capacity decreased after the silver nanoparticles agglomerate extensively. The surface plasmon resonance (SPR) excited between the silver nanoparticles and Rh. B interface is a physical origin and responsible for the boosted photoactivity, which strongly depends on the specific wavelength of the incident light. This work provides and suggests a novel scheme for Ag/Ag(3)PO(4) composites having plasmonic effect on the interface with detailed experimental and theoretical study.
    Journal of Colloid and Interface Science 11/2012; · 3.17 Impact Factor
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    ABSTRACT: CO(2) was converted into value-added hydrocarbons (methanol) by laser-induced photocatalytic reduction of CO(2) over commercially available silicon-carbide (SiC) granules as catalyst. The conversion of CO(2) was carried out in a glass reactor having quartz window and equipped with stirring system and was provided with continuous CO(2) flow at ambient conditions. Laser radiations of 355 nm, which were generated by third harmonics of Nd:YAG laser (1060 nm) were applied as an excitation source. The methanol yield as a function of irradiation time and catalysts dosage were monitored by the gas chromatographic analysis (GD-FID) of water samples collected at prescribed intervals. A specific GC column was used which separated hydrocarbons efficiently without any interference from water present in the sample. The study indicated that the commercially available SiC granular material is an excellent catalyst in laser-induced photocatalytic conversion of CO(2) into high value hydrocarbons.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 09/2012; 47(11):1571-6.
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    ABSTRACT: BiOCl-assisted photodegradation of Rhodamine B (Rh. B) molecules was investigated by using white light and green pulsed laser as sources of irradiation in the visible region for the first time. The dependences of removal efficiencies on catalyst dosage, incident pulsed laser energy were investigated and discussed. The dissolved oxygen was found to play an important role during the photochemical reaction. In addition the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) levels of Rh. B molecular were calculated using a Gaussian 03 program. These calculations were valuable to identify the possible photo-catalytic excitation process involved in degradation of Rh.B.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 07/2012; 47(8):1192-200.
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    ABSTRACT: Development of a photocatalyst with high efficiency and separability is still a challenging task in the field of wastewater treatment. In this study, new magnetic separable C/TiO(2)/Ni composite as a photocatalyst was prepared by a facile pyrolysis reaction, using powdered activated carbon (PAC), TiO(2) and Ni(Ac)(2) as precursors. The results proved that the photocatalyst (C/TiO(2)/Ni) synthesized in this work exhibited greater removal activity for Methyl Orange (MO) dye from water as compared with the commercially available well reported TiO(2) nanoparticles (P25). This significant enhancement in the photocatalytic activity for wastewater treatment due to the combination of PAC and TiO(2) could be presumed as the synergetic effect on the contacting interface of TiO(2) and PAC, and such effect was initially demonstrated by electrochemical impedance measurements. Furthermore, the trait that it consists of magnetic properties and therefore is easy to be recycled, which could be harnessed by an external magnet and may have many advantages over pure metal oxides (like TiO(2)) especially in the industrial procedures.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 03/2012; 47(4):570-6.
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    ABSTRACT: The main aim of this study was to synthesize magnetic separable Nickel/powdered activated carbon (Ni/PAC) and its application as an adsorbent for removal of PFOS from aqueous solution. In this work, the synthesized adsorbent using simple method was characterized by using X-ray diffractionometer (XRD), surface area and pore size analyzer, vibrating sample magnetometer (VSM), and high resolution transmission electron microscope (HRTEM). The surface area, pore volume and pore size of synthesized PAC was 1521.8 m(2)g(-1), 0.96 cm(3)g(-1), 2.54 nm, respectively. Different kinetic models: the pseudo-first-order model, the pseudo-second-order model, and three adsorption isotherms--Langmuir, Freundlich and Temkin--were applied to study the sorption kinetics and isothermal behavior of PFOS onto the surface of an as-prepared adsorbent. The rate constant using the pseudo-second-order model for removal of 150 ppm PFOS was estimated as 8.82×10(-5) and 1.64×10(-4) for PAC and 40% Ni/PAC, respectively. Our results demonstrated that the composite adsorbents exhibited a clear magnetic hysteretic behavior, indicating the potential practical application in magnetic separation of adsorbents from aqueous solution phase as well.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 11/2011; 46(13):1482-90.
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    ABSTRACT: The article deals with the synthesis of highly active visible-light-driven nanocomposite for the decontamination of water hazards under sunlight-type excitation. The surface of visible-light-active nanostructured photocatalyst tungsten oxide (WO3) was modified with noble metals, such as platinum (Pt) and gold (Au) nanoparticles, and the resulting photocatalytic activity of the nanocomposites was investigated by studying the removal of Methyl Orange and 2,4-Dichlorophenoxyacetic acid (2,4-D) under sunlight-type excitation. The study revealed that the deposited noble metals are not always favorable for the enhancement of photocatalytic response of catalysts; the activity of WO3 was enhanced manyfold (∼8 times) by depositing an optimum amount of Pt nanoparticles after certain photodeposition time whereas the presence of Au nanoparticles onto the WO3 surface, under identical experimental conditions, affected the removal process negatively. The variation in the photocatalytic activity of nanocomposites was attributed to the size of the deposited metals; Pt nanoparticles were uniformly dispersed with narrow size distribution (2–4 nm) while the size distribution of Au nanoparticles was found to be 10–15 nm for similar preparation conditions. The effects of critical parameters, such as metal deposition time and metal contents, on the photocatalytic activity of WO3 were investigated. Furthermore, Pt/WO3 nanocomposites showed good stability and recyclability under the conditions studied.
    Solid State Sciences. 09/2011; 13(9):1748–1754.
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    ABSTRACT: Single-crystalline Gallium Nitride (GaN) thin films were fabricated and grown by metal organic chemical vapor deposition (MOCVD) method on c-plane sapphire substrates and then characterized by high resolution-X-ray diffraction (HR-XRD) and photoluminescence (PL) measurements. The photocatalytic decomposition of Sulforhodamine B (SRB) molecules on GaN thin films was investigated under 355 nm pulsed UV laser irradiation. The results demonstrate that as-grown GaN thin films exhibited efficient degradation of SRB molecules and exhibited an excellent photocatalytic-activity-stability under UV pulsed laser exposure.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 03/2011; 46(4):415-9.
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    ABSTRACT: The photocatalytic degradation of Safranin-O (known as Basic Red 2) in water using locally synthesized nanocrystalline WO(3) as a photocatalyst was investigated under UV laser irradiation. The photo-oxidation removal of the dye was monitored by UV-vis spectrophotometer. The blank experiments for either laser irradiated only Safranin-O solution or the suspension containing WO(3) and Safranin-O in the dark showed that both laser illumination and the photocatalyst were essential for the removal of Safranin-O. The effect of experimental parameters including laser energy, catalyst loading, solution pH and the initial dye concentration on photocatalytic degradation of Basic Red 2 were also investigated. Results indicate that the rate of reaction is strongly influenced by the adsorption of an azo dye into the surface of the photocatalyst materials and suggests an optimum catalyst loading and dye concentration for the degradation reaction. It was investigated that the adsorption of the dye decreases at higher alkaline pH because both catalyst and substrate are negatively charged, developing repulsive forces between them. Kinetic data obtained reveals that the rate of the reaction obeys the first-order kinetics.
    Journal of hazardous materials 02/2011; 186(2-3):1226-33. · 4.14 Impact Factor
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    ABSTRACT: Nano particles exhibit physical and chemical properties distinctively different from that of bulk due to high number of surface atoms, surface energy and surface area to volume ratio. Laser is a unique source of radiation and has been applied in the synthesis of nano structured metal oxides. The pulsed laser ablation (PLA) technique in liquid medium has been proven an effective and simple technique for preparing nanoparticles of high purity. Pulsed laser deposition (PLD) is another way to fabricate nano structured single crystal thin films of metal oxides. PLA technique has been applied in our laboratory for the growth of metal oxides such as nano-ZnO, nano-ZnO2 nano- SnO2, nano-Bi2O3, nano-NiO and nano-MnO2. Different techniques such as AFM, UV, FT-IR, PL and XRD were applied to characterize these materials. We will present our latest development in the growth of nano metal oxides using PLA and PLD.
    Proc SPIE 02/2011;
  • M Qamar, M A Gondal, Z H Yamani
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    ABSTRACT: The present study demonstrates the complete removal of Cr(VI) in aqueous suspensions of zinc oxide nanoparticles using a novel laser-induced photocatalytic process without the use of any additive. The study showed that ∼95% Cr(VI) was removed within short time (60 min) of laser exposure in the presence of ZnO. However, the removal of chromium using conventional setup under identical conditions was found to be negligible. Effect of critical parameters, such as laser energy, catalyst concentration, chromium concentration, and added electron donor and acceptor on the photocatalytic reduction process was also investigated. The data regarding temporal behavior of metal removal was fitted to first-order kinetic and reaction rate was computed.
    Journal of hazardous materials 01/2011; 187(1-3):258-63. · 4.14 Impact Factor
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    ABSTRACT: Nanostructured ZnO photo catalyst was synthesized by precipitation method and was applied in conjunction with 355nm pulsed laser irradiation for effective disinfection of the water contaminated with Escherichia coli micro organism. The morphological studies using X-Ray Diffractometer (XRD) and Transmission Electron Microscope (TEM) were carried out on the synthesized nano-ZnO, and these studies indicated that the catalyst has the crystallographic structure of hexagonal wurtzite and has the grain size of around 20–40nm. The bacteria decay rate constants were estimated for nine different concentrations of nano-ZnO in infected water. The parametric optimization was carried out, and we could reach the decay rate constant as high as 0.24min,−1 which is higher than micro-structured ZnO and the familiar TiO2 photo catalysts under similar experimental condition. KeywordsSynthesis of nano-structured ZnO–Laser induced photo catalysis–Water disinfection–Waste water treatment– E. Coli –Health effects
    Journal of Nanoparticle Research 01/2011; 13(8):3423-3430. · 2.18 Impact Factor
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    ABSTRACT: a b s t r a c t Multi-walled carbon nanotube/zinc oxide (MWCNT/ZnO) composites were synthesized by thermal hydrolysis method. The composites were prepared using multi-walled carbon nanotubes (MWCNTs) as a starting material, and zinc nitrate as a precursor. For characterization and morphological studies, different techniques such as FE-SEM, HRTEM, XRD, UV and FT-IR were applied. The photo catalytic activ-ity of the prepared composite was evaluated by measuring the degradation of acetaldehyde in aqueous solution under UV laser irradiation. Almost 50% enhancement in photocatalytic activity for removal of acetaldehyde was recorded by embedding ZnO nanoparticles on the surface of MWCNTs.
    Chemical Engineering Journal. 01/2011; 166:407-412.
  • M. Qamar, M. A. Gondal, Z. H. Yamani
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    ABSTRACT: Owing to its high toxicity, chromium(VI) is considered as top priority pollutant for many countries in the world and removal of this pollutant from waste water is highly desirable. The present investigation addresses the synthesis of NiO nanoparticles using sol–gel method and their application in heterogeneous photocatalytic reduction of Cr(VI) using a 355nm laser radiation generated from Nd:YAG laser. The study showed that ∼90% Cr(VI) was removed within short laser exposure time (75min) in presence of nanostructured NiO without the use of any additive as reported in other studies. Effect of critical parameters, such as calcination temperature, calcination time, laser energy, catalyst amount, chromium concentration, and added electron donor and acceptor on the photocatalytic reduction process was investigated. The photocatalytic reduction of metal was found to be strongly dependant on the above mentioned parameters.
    Journal of Molecular Catalysis A-chemical - J MOL CATAL A-CHEM. 01/2011; 341(1):83-88.
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    ABSTRACT: The adsorption (under dark condition) and photodegradation behaviors of Rhodamine B molecules on BiOBr under visible (532 nm) pulsed laser exposure were studied and reported for the first time. The adsorption kinetics/isotherm behaviors and thermodynamic process (adsorption dynamical parameters) occurred on as-prepared BiOBr were investigated. The photodegradation mechanisms, effects of BiOBr dosage and pulsed laser energy on dye removal efficiency in the presence of BiOBr particles were studied as well. Furthermore, the photodegradation of other kinds of Rhodamine dyes such as Rhodamine 6G, Sulforhodamine B and Sulforhodamine 640 were initially investigated and compared under 532 nm pulsed laser exposure. The study also demonstrated that the dissolved oxygen plays a very significant role in the photo-catalytic decomposition of Rhodamine. The BiOBr catalyst was found intact even under acidified conditions showing good stability of the catalyst.Graphical abstract.View high quality image (140K)Highlights► The BiOBr photocatalyst was synthesized at our laboratory. ► The structures of BiOBr before/after photochemical reaction were determined by XRD. ► The adsorption/degradation of RhB under 532 nm pulsed laser exposure were studied. ► The effects of BiOBr dosage/pulsed laser energy on dye removal were investigated. ► It was proved the dissolved O2 plays a key role in the photodegradation of RhB.
    Applied Catalysis A: General. 01/2011; 397:192-200.
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    ABSTRACT: A laser-induced breakdown spectroscopy (LIBS) setup was developed to detect lead and other toxic contaminants such as chromium in paint emulsion samples manufactured in Saudi Arabia. The lead concentration detected in these samples was in the 327.2-755.3 ppm range, which is much higher than the safe permissible limit set by Saudi regulatory agencies. Similarly, chromium concentration (98.1-149.5 ppm) was found in high concentrations as well. The results obtained with our LIBS setup are comparable with the sample analysis utilizing a standard technique such as ICP, and our LIBS results are comparable to ICP with in an accuracy limit of 2-4 %.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 01/2011; 46(1):42-9.
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    ABSTRACT: Nano palladium-loaded on nano tungsten trioxide (n-Pd/n-WO3), with 10% wt Pd loading, was prepared by the impregnation evaporation method. The n-WO3 support was prepared by dehydration of tungstic acid (H2WO4). The n-Pd/n-WO3 was characterized by Raman spectroscopy, X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). This material was tested as a photocatalyst for inactivation and killing of coliform bacteria, by applying 355-nm pulsed UV laser radiations, generated from the third harmonic of Nd:YAG laser, to a model water sample, prepared using bacteria strains of Escherichia coli. The killing effect of n-Pd/n- WO3 on coliform bacteria was characterized by means of selective culture media. The photocatalysis process did result in a very high irreversible injury (99%) under investigated conditions. This process is cost-effective because no bacteria re-growth was recorded under optimum environment conditions. The disinfection rate of water was estimated by exponential decay. The conventional titania (TiO2) semiconductor and commercially available WO3 display a lower decay rate than that for n-Pd/n-WO3.
    Studies in Surface Science and Catalysis - STUD SURF SCI CATAL. 01/2010; 175:279-282.

Publication Stats

193 Citations
395 Downloads
3k Views
66.99 Total Impact Points

Institutions

  • 2004–2014
    • King Fahd University of Petroleum and Minerals
      • • Center of Research Excellence in Nanotechnology
      • • Department of Physics
      Az̧ Z̧ahrān, Eastern Province, Saudi Arabia
  • 2011
    • Nanjing University of Aeronautics & Astronautics
      • Department of Applied Chemistry
      Nanjing, Jiangsu Sheng, China
  • 2007
    • National University of Science and Technology
      • Institute of Environmental Sciences and Engineering
      Islāmābād, Islamabad Capital Territory, Pakistan