Browsing by Author "Abbas, Nadir"

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    Aminated polyethersulfone-silver nanoparticles (AgNPs-APES) compositemembranes with controlled silver ion release for antibacterial and water treatment applications
    (Materials Science and Engineering C, 2016-02-10) Haider, M. Salman; Shao, Godlisten N.; Imran, S.M; Park, Seongsoo; Abbas, Nadir; Tahir, M.S; Hussain, Manwar; Bae, Wookeun; Kim, HT
    The present study reports the antibacterial disinfection properties of a series of silver nanoparticle (AgNP) immobilized membranes. Initially, polyethersulfone (PES) was functionalized through the introduction of amino groups to form aminated polyethersulfone (NH2-PES, APES). AgNPs were then coordinately immobilized on the surface of the APES composite membrane to formAgNPs-APES. The properties of the obtainedmembrane were examined by FT-IR, XPS, XRD, TGA, ICP-OES and SEM-EDAX analyses. These structural characterizations revealed that AgNPs ranging from 5 to 40 nm were immobilized on the surface of the polymer membrane. Antibacterial tests of the samples showed that the AgNPs-APES exhibited higher activity than the AgNPs-PES un-functionalized membrane. Generally, the AgNPs-APES 1 cm × 3 cm strip revealed a four times longer life than the un-functionalized AgNPs polymer membranes. The evaluation of the Ag+ leaching properties of the obtained samples indicated that approximately 30% of the AgNPs could be retained, even after 12 days of operation. Further analysis indicated that silver ion release can be sustained for approximately 25 days. The present study provides a systematic and novel approach to synthesize water treatment membranes with controlled and improved silver (Ag+) release to enhance the lifetime of the membranes.
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    Electroconductive performance of polypyrrole/graphene nanocomposites synthesized through in situ emulsion polymerization
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2014-11-22) Imran, S.M; Shao, Godlisten N.; Haider, M. Salman; Abbas, Nadir; Hussain, Manwar; Kim, HT
    The present study demonstrates a modified in situ emulsion polymerization (EP) approach convenient for the formation of polypyrrole/graphene (PPy/GN) nanocomposites with harnessed conductivities. A series of PPy/GN nanocomposites were prepared by loading different weight percent (wt %) of GN during in situ EP of pyrrole monomer. The polymerization was carried out in the presence of dodecyl benzene sulfonic acid, which acts as an emulsifier and protonating agent. The microstructures of the nanocomposites were studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectroscopy, UV–vis spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and thermogravimetric analyses. The electrical conductivities of the nanocomposite pellets pressed at different applied pressures were determined using four probe analyzer. The electrical conductivities of the nanocomposites were considerably enhanced as compared to those of the individual PPy samples pressed at the same pressures. An enhanced conductivity of 717.06 S m21 was observed in the sample with 5 wt % GN loading and applied pressure of 8 tons. The results of the present study signify that the addition of GN in the PPy polymer harnesses both electrical and thermal properties of the polymer. Thus, PPy/GN nanocomposites with superior properties for various semiconductor applications can be obtained through direct loading of GN during the polymerization process.
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    Facile, Single-pot preparation of nanoporous SiO2 particles (carrier) with AgNPs at core and crust for controlled disinfectant release
    (Journal of Saudi Chemical Society, Elsevier B.V., 2019-03-11) Haider, M. Salman; Shao, Godlisten N.; Ahmad, Ahmad; Imran, S. Muhammad; Abbas, Nadir; Abbas, Ghulam; Hussein, Manwar; Kim, Hee Taik
    This study demonstrates a novel, facile and one-pot approach to synthesize silica nanoparticles with silver at core and crust (SiNP-AgCC). A modified Stöber method was used to make SiNP-AgCC. A significant reduction in the size of SiO2 nanoparticles was seen, with 2–5 nm AgNPs being uniformly distributed on the surface and 10–20 nm AgNPs in the center. A typical mesoporous SiO2 particle (SiNP) produced using the Stöber method was transformed to nanoporous SiO2 by this modified Stöber method. Nanoporous SiO2 particles with silver in the center are advantageous for slow and consistent Ag+ release, which was confirmed by Ag+ ion release test. Antibacterial activities of the samples were tested to evaluate the disinfection performance of the samples on gram-negative bacteria (Escherichia coli) using disk diffusion and the LB-agar method. SiNP-AgCC showed prolonged silver release for more than 20 days and improved antibacterial properties even after five days of incubation.
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    Inexpensive sol-gel synthesis of multiwalled carbon nanotube-TiO2 hybrids for high performance antibacterial materials
    (Materials Science and Engineering: C, Elsevier, 2016-11-01) Abbas, Nadir; Shao, Godlisten N.; Kim, Heetaik
    This study reports an inexpensive sol-gel method to synthesize TiO2-CNT hybrid materials. Synthesized TiO2-CNT materials show strong antibacterial activity in the absence of light. Cheap TiO2 source TiOCl2 is used during synthesis in the absence of high temperatures, high pressures and organic solvents. TiO2-CNT materials with 0, 2, 5, 10, 15 and 20 wt% of CNT were synthesized and compared for antibacterial activity, surface area, porosity, crystalline structure, chemical state, and HaCaT cell proliferation. The antibacterial strength of hybrid materials increased significantly with the increase in CNT loading amount, and the TiO2-CNT samples with a CNT loading of 10 wt% or more nearly removed all of the E.coli bacteria. HaCaT cell proliferation studies of synthesized hybrid materials illustrated that prepared TiO2-CNT systems exhibit minimum cytotoxicity. The characteristics of prepared materials were analyzed by means of XRD, FTIR, Raman spectroscopy, XPS, TEM, and nitrogen gas physisorption studies, compared and discussed
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    Inexpensive synthesis of a high-performance Fe3O4-SiO2-TiO2 photocatalyst: Magnetic recovery and reuse
    (Springer, 2016) Abbas, Nadir; Shao, Godlisten N.; Kim, Heetaik
    A sol-gel technique has been developed for the synthesis of a magnetite-silica-titania (Fe3O4-SiO2-TiO2) tertiary nanocomposite with improved photocatalytic properties based on the use of inexpensive titania and silica precursors. The exceptional photocatalytic activity of the resulting materials was demonstrated by using them to photocatalyze the degradation of methylene blue solution. The best formulation achieved 98% methylene blue degradation. An interesting feature of the present work was the ability to magnetically separate and reuse the catalyst. The efficiency of the catalyst remained high during two reuses. The synthesized nanomaterials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, ultra-violet-visible spectroscopy, diffuse reflectance spectroscopy, and thermogravimetric analysis. XRD analysis revealed the formation of multicrystalline systems of cubic magnetite and anatase titania crystals. SEM and TEM characterization revealed well-developed and homo-geneously dispersed particles of size less than 15 nm. FTIR spectra confirmed the chemical interaction of titania and silica. It was further noticed that the optical properties of the prepared materials were dependent on the relative contents of their constituent metal oxides.
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    Sol-gel synthesis of less expensive mesoporous titania-tin dioxide systems: Investigation of the influence of tin dioxide on the phase structure, morphology and optical properties
    (Elsevier, 2017) Shao, Godlisten N.; Imran, S.M; Abbas, Nadir; Kim, Heetaik
    Herein the influence of SnO2 on the optical, morphology and phase structure of mesoporous TiO2-SnO2 composites was examined. Composites with Sn/Ti ratio ranging from 0.1 to 5 were synthesized using less expensive sources in the absence of additives. The obtained samples were examined by XRD, HRTEM, SEM-EDAX, XPS, UV–vis DRS, XRF, TGA and nitrogen gas physisorption studies analyses. The physicochemical properties of the TiO2-SnO2 systems depended mainly on the Sn-to-Ti ratio, calcination temperature and the interaction between Sn4+and Ti4+. XRD results depicted that samples with Sn/Ti = 0.1 calcined at ≤600 °C exhibited pure anatase TiO2 crystals and the tendency of increasing Sn4+ content facilitated a phase transformation to attain rutile structure. Optical analyses of the samples showed that the absorption of the samples can be extended into the visible region. This study provides a systematic and economical method for large-scale production of TiO2 based composites with desirable properties for various applications.
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    Sol–gel synthesis of photoactive zirconia–titania from metal salts and investigation of their photocatalytic properties in the photodegradation of methylene blue
    (Powder Technology, 2014-03-11) Shao, Godlisten N.; Imran, S.M; Jeon, Sunjeong; Engole, Marion; Abbas, Nadir; Haider, M. Salman; Kang, Shin Jae; Kim, HT
    Photoactivemetal oxide systems capable of reducing non-biodegradable pollutants are highly needed heterogeneous catalysts for environmental purification. Most of the currently available heterogeneous catalysts are obtained from complicated synthetic routes using expensive and perhaps hazardous precursors. The present study reports a novel sol–gelmethod to synthesize pure TiO2 and ZrO2–TiO2 samples using titanium oxychloride as TiO2 precursor and zirconyl nitrate hydrate as a ZrO2 source in the presence of the surfactant. The ratio of Zr-to- Ti was controlled between 0.75 and 3.2 to evaluate the effect of the amount of ZrO2 in the composites. Consequently, the precipitates were calcined at different temperatures to investigate the effect of removing the template at different sintering temperatures. The physico-chemical properties of the samples were examined by SEM, HRTEM, DT-TGA, XRD, FTIR, XRF, EDX, nitrogen gas physisorption and UV–visible diffusive reflectance spectrometry analyses. These analyses revealed that the crystallization, dispersion, particle size and shape of the samples are critically dependent upon the calcination temperatures and Zr-to-Ti ratios. Abnormal grain growth (AGG) was unexpectedly observed in the samples calcined at higher temperatures (≤800 °C). Comparisons of the activities of the samples toward decolorization of methylene blue indicated that the photocatalytic efficiencies of the composites with Zr/Ti ≤ 2.2 were superior to that of pure TiO2.
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    Sol–gel synthesis of TiO2-Fe2O3 systems: Effects of Fe2O3 content and their photocatalytic properties
    (Elsevier, 2016) Abbas, Nadir; Shao, Godlisten N.; Kim, Heetaik
    An inexpensive sol–gel technique to synthesize TiO2-Fe2O3 nanocomposites with improved structural and photochemical properties is introduced. A series of TiO2-Fe2O3 nanocomposites with different Fe2O3 contents were prepared through cheap TiO2 precursor titanium oxychloride (TiOCl2). The physicochemical properties of the samples were examined by XRD, XRF, SEM, EDX, HRTEM, UV–vis DRS, FTIR, TGA and nitrogen gas physisorption studies. The effects of calcination temperatures and Fe2O3 content on the mesostructure and photocatalytic strength of the prepared TiO2-Fe2O3 composites were investigated. Results showed that composites with distinct structural, optical and photochemical properties can be formed by varying Fe2O3 content.