Tawfik A. Saleh

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

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Publications (36)67.94 Total impact

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    ABSTRACT: This work reports the recycling of waste rubber tires (WRT) to produce a carbonaceous material as adsorbent of an environmental value. The produced material was activated by thermal–chemical process. The WRT-derived carbonaceous adsorbent (CA) was characterized by means of scanning electron microscope, energy-dispersive X-ray spectroscopy and infrared and Raman spectroscopic techniques. The developed CA was tested and evaluated as potential adsorbent for methyl orange (MO) removal. A series of MO stock solutions whose concentrations range from 1 × 10− 6 to 1 × 10− 4 M was prepared to investigate the possible activity of CA. Experimental parameters such as dosage amount, initial concentration and temperature were optimized. A rapid and fast equilibrium has been observed. The maximum adsorption took place in the pH range of 3–5. The temperature-effect study revealed that the process is exothermic. A possible adsorption mechanism has been suggested on the view of calculated frontier molecular orbitals of the methyl orange molecule.
    Journal of Molecular Liquids 01/2014; 191:85–91. · 1.68 Impact Factor
  • Tawfik A. Saleh, V.K. Gupta
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    ABSTRACT: The remarkable increase in the number of vehicles worldwide; and the lack of both technical and economical mechanisms of disposal make waste tires to be a serious source of pollution. One potential recycling process is pyrolysis followed by chemical activation process to produce porous activated carbons. Many researchers have recently proved the capability of such carbons as adsorbents to remove various types of pollutants including organic and inorganic species. This review attempts to compile relevant knowledge about the production methods of carbon from waste rubber tires. The effects of various process parameters including temperature and heating rate, on the pyrolysis stage; activation temperature and time, activation agent and activating gas are reviewed. This review highlights the use of waste-tires derived carbon to remove various types of pollutants like heavy metals, dye, pesticides and others from aqueous media.
    Advances in Colloid and Interface Science. 01/2014;
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    ABSTRACT: Pulsed laser ablation in liquid (PLAL) with 532 nm wavelength laser with 5 ns pulse duration is used to produce the nanostructure copper oxide and the effects of oxidizing media (deionized water and hydrogen peroxide) on the composition, morphology and optical properties of the product materials produced by PLAL were studied. XRD and TEM studies indicate that in the absence of hydrogen peroxide, the product material is in two phases (Cu/Cu2O) with the spherical nanoparticle structure, whereas in the presence of hydrogen peroxide in the liquid medium, the product material revealed other two phases (Cu/CuO) with nanorod-like structure. The optical studies revealed a considerable red shift (3.34-2.5 eV) in the band gap energy in the case of hydrogen peroxide in the liquid medium in PLAL synthesis compared to the one in the absence of it. Also the product material in the presence of hydrogen peroxide in the liquid medium showed a reduced photoluminescence intensity indicating the reduced electron-hole recombination rate. The red shift in the band gap energy and the reduced electron-hole recombination rate make the product material an ideal photocatalyst to harvest solar radiation for various applications. The most relevant signals on the FTIR spectrum for the samples are the absorption bands in the region between 450 and 700 cm-1 which are the characteristics bands of copperoxygen bonds. The reported laser ablation approach for the synthesis of Cu2O and CuO nanoparticles has the advantages of being clean method with controlled particle properties.
    Applied Surface Science 12/2013; · 2.54 Impact Factor
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    Preprints-American Chemical Society, Division of Energy Fuels, Indianapolis, Indiana, USA; 09/2013
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    ABSTRACT: Effective activated porous carbon (AC) was prepared by thermal treatment of waste rubber tires and was further activated using oxidizing agents like nitric acid and hydrogen peroxide. The tire-derived porous carbon was characterized by means of FTIR and X-ray diffraction. Careful analysis of the IR spectra of the synthesized AC reveals a number of bands centered at about 3400, 2350, 1710, 1650, and 1300-1000cm, proving the existence of hydroxyl and carboxylic groups on the surface of AC in addition to CC double bonds. The developed AC was tested and evaluated as a potential adsorbent for the removal of lead (II) ions. Experimental parameters, such as contact time, initial concentration, adsorbent dosage, and pH were optimized. AC was effective in a pH range between 4 and 7 with a highest uptake of lead ions at pH 5 and 6. For further understanding of the chemistry behind the process, density functional theory (DFT) calculations were performed at the B3LYP/6-31G(d) level adopting a functionalized pyrene molecule as a model. The binding energy of Pb(II) ion toward carboxylic acid, carbonyl, and hydroxyl groups was calculated. A binding energy in the range of 310-340kcal/mol, which is considered to be high and to be indicative of a chemisorptions process, was predicted. The adsorption of the lead ion toward the CO groups in relatively all cases shows more stable binding compared to the sorption toward the alcohol groups.
    Journal of Colloid and Interface Science 04/2013; 396:264-9. · 3.17 Impact Factor
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    ABSTRACT: Environmental friendly and clean transportation fuels are very important and worldwide desired fuels. It can be achieved by removing undesirable compounds/elements in fuel oil. Most prominent among these are sulfur compounds and up to a lesser extent nitrogen compounds. Thus removal of sulfur compounds from fuel oils has become very significant and gained maximum attention worldwide to produce better quality fuels without sulfur compounds or a minimum possible limit. We are reporting here results of our ongoing research project being carrying out using novel coated metaloxides for the adsorption and removal of sulphur compounds in model fuel oils. Dimethyl dibenzothiiophene (DMDBT) and Dibenzothiiophene (DBT), were mainly used in model fuel oil. Several reaction conditions were applied and at optimized conditions around 60-80% desulfurization was achieved. The initial results revealed that these coated metal oxides are very effective in adsorbing DMDBT and DBT on the surface of metal oxides. Overall the non-catalytic desulfurization process of adsorption provided very effective results and these metal oxides can further be modified to get more desired results.
    245th ACS National Meeting & Exposition, Preprints, Division of Energy and Fuels; 04/2013
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    ABSTRACT: Adsorption is a widely used technique for the separation and removal of pollutants from wastewaters. Carbon nanotubes (CNTs) are emerging as potential adsorbents because of its well defined cylindrical hollow structure, large surface area, high aspect ratios, hydrophobic wall and easily modified surfaces. In this review, dye adsorption capability of CNTs and CNT based composites from aqueous system has been compiled. This article provides the information about the defect, adsorption sites on CNTs and batch adsorption studies under the influence of various operational parameters such as contact time, solution pH, temperatures etc. and deals with mechanisms involved in adsorption of dyes onto CNTs. From the literature reviewed, it is observed that single walled carbon nanotubes (SWCNTs) show higher adsorption capacity than multi walled carbon nanotubes (MWCNTs) and functionalized and CNT composite have better sorption capacity than as grown CNTs. It is evident from the literature that CNT based nanosorbents have shown good potential for the removal of dyes from aqueous solution. However, still more research work should be focused on the development of cost effective, higher efficient and environmental friendly CNT based nanosorbents for their commercial applications.
    Advances in colloid and interface science 03/2013; · 5.68 Impact Factor
  • Vinod K Gupta, Tawfik A Saleh
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    ABSTRACT: The quality of water is continuously deteriorating due to its increasing toxic threat to humans and the environment. It is imperative to perform treatment of wastewater in order to remove pollutants and to get good quality water. Carbon materials like porous carbon, carbon nanotubes and fullerene have been extensively used for advanced treatment of wastewaters. In recent years, carbon nanomaterials have become promising adsorbents for water treatment. This review attempts to compile relevant knowledge about the adsorption activities of porous carbon, carbon nanotubes and fullerene related to various organic and inorganic pollutants from aqueous solutions. A detailed description of the preparation and treatment methods of porous carbon, carbon nanotubes and fullerene along with relevant applications and regeneration is also included.
    Environmental Science and Pollution Research 02/2013; · 2.76 Impact Factor
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    ABSTRACT: The aim of this work was to investigate the utilization of waste tire carbons as a low cost adsorbent for removal of cadmium (II) ion from aqueous solution with density functional theory calculations to shed more light on the adsorption process. Thus, activated carbon was prepared from waste rubber tires and characterized by means of field emission scanning electron microscopy, energy-dispersive X-ray and Fourier transform infrared spectroscopies. Effect of various operating parameters like contact time, dosage, agitation speed and pH on the removal of Cd(II) from aqueous solution by the batch adsorption technique was investigated. The adsorption process was relatively fast and the equilibrium was reached after about 60 min of contact. Characterization of activated carbon after adsorption was also conducted. Density functional theory (DFT) calculations were performed to estimate the binding energy of Cd2 + ions towards carboxylic acid, carbonyl and hydroxyl groups. The calculated binding energy of the adsorption process was predicted to be in the range of 190–212 kcal/mol, and the Cd2 + ion tends to approach more conveniently towards the carbonyl's oxygen atom in the carboxylic acid and carbonyl groups. The developed sorbent exhibited the advantages of being inexpensive and of double benefit to the environment.
    Journal of Molecular Liquids 01/2013; 188:136–142. · 1.68 Impact Factor
  • ChemInform 11/2012; 43(45).
  • Tawfik A. Saleh, Vinod K. Gupta
    Current Nanoscience 10/2012; 8(5):739-743. · 1.36 Impact Factor
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    ABSTRACT: The global population is increasing and because of this, the world may experience great fresh water scarcity. Our water resources are limited and, hence, water treatment and recycling methods are the only alternatives for getting fresh water in the coming decades. Therefore, there is a great need for the development of a suitable, inexpensive and rapid wastewater treatment techniques and reuse or conservation methods in the present century. The different types of water treatment and recycling techniques have been discussed in terms of their basic principles, applications, costs, maintenance and suitability. Additionally, a systematic approach to water treatment and recycling involving their understanding, evaluation and selection parameters has been presented. A brief guideline for the selection of the appropriate technologies for specific applications has been evaluated. This review adds to the global discussions on water scarcity solutions.
    RSC Advances 07/2012; 2(16):6380-6388. · 3.71 Impact Factor
  • M.A. Gondal, Tawfik A. Saleh, Q.A. Drmosh
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    ABSTRACT: Nanomaterials are of great interest due to their applications in many fields. The structural and efficacy of nano-materials depend strongly on the method applied for their synthesis. In this work, nanosized nickel oxide (NiO) particles were prepared by pulsed laser ablation (PLA) technique in 3% H2O2 aqueous solution The structural and optical properties of the NiO were investigated by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscope (EDX), UV–Vis spectroscopy and Fourier-transform infrared spectroscopy (FT-IR). XRD analysis confirms that the phase is pure nickel oxide with lattice parameter = 0.42033 nm and 8 nm grain size while photoluminescence emission spectrum showed strong peak at 3.62 eV attributed to the band edge transition. FT-IR spectra depicts a strong band at ∼450 cm−1 which corresponds to the bending vibration of Ni–O bond. This work demonstrates that PLA is an effective method to control the size, impurity and minimal chemical waste generation which is the major problem with other wet chemical methods.
    Applied Surface Science 07/2012; 258(18):6982–6986. · 2.54 Impact Factor
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    ABSTRACT: Because of the continuous production of large amount of waste tires, the disposal of waste tires represents a major environmental issue throughout the world. This paper reports the utilization of waste tires (hard-to-dispose waste) as a precursor in the production of activated carbons (pollution-cleaning adsorbent). In the preparation of activated carbon (AC), waste rubber tire (WRT) was thermally treated and activated. The tire-derived activated carbon was characterized by means of scanning electron microscope, energy-dispersive X-ray spectroscopy, FTIR spectrophotometer, and X-ray diffraction. In the IR spectrum, a number of bands centred at about 3409, 2350, 1710, 1650, and 1300-1000 cm(-1) prove the present of hydroxyl and carboxyl groups on the surface of AC in addition to C═C double bonds. The developed AC was tested and evaluated as potential adsorbent removal of chromium (III). Experimental parameters, such as contact time, initial concentration, adsorbent dosage and pH were optimized. A rapid uptake of chromium ions was observed and the equilibrium is achieved in 1 h. It was also found that the adsorption process is pH dependent. This work adds to the global discussion of the cost-effective utilization of waste rubber tires for waste water treatment.
    Environmental Science and Pollution Research 05/2012; · 2.76 Impact Factor
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    Tawfik A Saleh, A M Abulkibash, Atta E Ibrahim
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    ABSTRACT: A simple and fast-automated method was developed and validated for the assay of promethazine hydrochloride in pharmaceutical formulations, based on the oxidation of promethazine by cerium in an acidic medium. A portable system, consisting of a programmable syringe pump connected to a potentiometer, was constructed. The developed change in potential during promethazine oxidation was monitored. The related optimum working conditions, such as supporting electrolyte concentration, cerium(IV) concentration and flow rate were optimized. The proposed method was successfully applied to pharmaceutical samples as well as synthetic ones. The obtained results were realized by the official British pharmacopoeia (BP) method and comparable results were obtained. The obtained t-value indicates no significant differences between the results of the proposed and BP methods, with the advantages of the proposed method being simple, sensitive and cost effective.
    Saudi Pharmaceutical Journal 04/2012; 20(2):155-60. · 0.95 Impact Factor
  • Tawfik A Saleh, Vinod K Gupta
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    ABSTRACT: The high rate of electron/hole pair recombination reduces the quantum yield of the processes with TiO(2) and represents its major drawback. Adding a co-adsorbent increases the photocatalytic efficiency of TiO(2). In order to hybridize the photocatalytic activity of TiO(2) with the adsorptivity of carbon nanotube, a composite of multi-walled carbon nanotubes and titanium dioxide (MWCNT/TiO(2)) has been synthesized. The composite was characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared absorption spectroscopy (FTIR), and diffuse reflectance UV-vis spectroscopy. The catalytic activity of this composite material was investigated by application of the composite for the degradation of methyl orange. It was observed that the composite exhibits enhanced photocatalytic activity compared with TiO(2). The enhancement in photocatalytic performance of the MWCNT/TiO(2) composite is explained in terms of recombination of photogenerated electron-hole pairs. In addition, MWCNT acts as a dispersing agent preventing TiO(2) from agglomerating activity during the catalytic process, providing a high catalytically active surface area. This work adds to the global discussion of how CNTs can enhance the efficiency of catalysts.
    Journal of Colloid and Interface Science 04/2012; 371(1):101-6. · 3.17 Impact Factor
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    ABSTRACT: The photo-catalytic degradation of an azo dye - Amaranth (AM) - has been investigated in TiO(2)/UV aqueous suspensions. The results obtained from the experiments during H(2)O(2)/TiO(2) addition show that the highest decolorization rate is provided by the combination of (UV+TiO(2)+H(2)O(2)). The decolorization efficiencies were 17%, 26%, 38% and 64% in the runs UV, UV+H(2)O(2), UV+TiO(2) and (UV+TiO(2)+H(2)O(2)) after approximately 100min illumination periods, respectively. The observed dye degradation rates followed pseudo-first order kinetics with respect to the substrate concentration under the experimental conditions used. Different experimental conditions, such as temperature, pH and presence of electron acceptor were investigated. The temperature effect was investigated at the range of 293-313K and it was observed that decolorization rate increased by the increase in temperature. Chemical oxygen demand and dye absorbance of the photodegraded dye solution substantially decreased. Effect of pH was also investigated and it was observed that the lower the pH the higher the degradation. In addition, an enhancement in the photodegradation rate was observed by the addition of hydrogen peroxide as an electron acceptor. The adsorption trends of Amaranth at various initial concentrations followed the Langmuir isotherm trend. This work adds to the global discussion on the role of the advanced oxidation processes in water treatment.
    Materials science & engineering. C, Materials for biological applications. 01/2012; 32(1):12-7.
  • Tawfik A Saleh, Vinod K Gupta
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    ABSTRACT: In this study, manganese dioxide-coated multiwall carbon nanotube (MnO(2)/CNT) nanocomposite has been successfully synthesized. The as-produced nanocomposite was characterized by different characteristic tools, such as X-ray diffraction, SEM, and FTIR. The MnO(2)/CNT nanocomposite was utilized as a fixed bed in a column system for removal of lead(II) from water. The experimental conditions were investigated and optimized. The pH range between 3 and 7 was studied; the optimum removal was found when the pH was equal to 6 and 7. The thickness of MnO(2)/CNT nanocomposite compact layer was also changed to find the optimum parameter for higher removal. It was observed that the slower the flow rates of the feed solution the higher the removal because of larger contact time.
    Environmental Science and Pollution Research 11/2011; 19(4):1224-8. · 2.76 Impact Factor
  • Tawfik A Saleh, Vinod K Gupta
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    ABSTRACT: A composite of multi-walled carbon nanotube/tungsten oxide (MWCNT/WO(3)) has been successfully synthesized. The prepared composite was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR). The catalytic activity was investigated by rhodamine B degradation under solar irradiation. The influence of various degradation parameters such as solar illumination time, initial dye concentration, dosage and pH was investigated. It was found that the composite exhibits an enhanced photocatalytic activity as compared with WO(3) and a mechanical mixture of MWCNTs and WO(3). The enhancement in photocatalytic performance of the MWCNT/WO(3) composite has been explained based on adsorption ability and electron transportation as a result of a strong interaction between WO(3) and MWCNTs. Besides, MWCNTs acts as dispersing agent preventing WO(3) from agglomerating during the catalytic process, providing a high active surface area of the catalyst. A reasonable mechanism for the enhanced reactivity was proposed.
    Journal of Colloid and Interface Science 10/2011; 362(2):337-44. · 3.17 Impact Factor
  • Tawfik A. Saleh, Shilpi Agarwal, Vinod K. Gupta
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    ABSTRACT: It is well known that arsenite [As(III)] is less effectively removed than arsenate [As(V)] by most treatment technologies. Thus, pre-oxidation of As(III) to As(V) is required prior to adsorption. Here, the oxidation properties of manganese oxides with adsorption features of multiwall carbon nanotubes (MWCNTs) have been combined in a composite of MWCNT/MnO2. The composite was characterized by Fourier transform infrared absorption spectroscopy (FTIR), field emission scanning electron microscope (FESEM), and energy dispersive X-ray (EDX) and X-ray diffraction (XRD). In batch culture experiments, MWCNTs and the MWCNT/MnO2 composite were examined for As(III) and As(V). The results reveal that MnO2 in the composite plays a key role in enhancing As(III) removal and As(III) removal is not as effective as As(V) removal for MWCNTs. The retention of arsenite and arsenate is slightly pH dependent. The reported composite can be regenerated as it was confirmed by SEM and EDX analysis. The study could be considered as a model of preparation and investigation of a multifunctional material that can be used in wastewater treatment for removal of arsenic.
    Applied Catalysis B: Environmental. 07/2011; 106(s 1–2):46–53.