Yazar "Siddiq, Mohammed" seçeneğine göre listele

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    Cationic microgels embedding metal nanoparticles in the reduction of dyes and nitro-phenols
    (Elsevier Science Sa, 2015) Rehman, Saif Ur; Siddiq, Mohammed; Al-Lohedan, Hamad; Şahiner, Nurettin
    Cationic microgels of p(3-Acrylamidopropy1)-trimethylammonium chloride (p(APTMACI)) were synthesized using the inverse suspension polymerization technique, and the obtained microgels were used as microreactor for in situ synthesis of Co, Ni, and Cu nanoparticles. The p(APTMAC1) microgels were loaded with Co,.Ni, and Cu after contact with chloride salts of the metals, CoCl2, NiCl2, and CuCl2, in ethanol and reduced to their respective metal nanoparticles by treating them with sodium borohydride (NaBH4) as reducing agent. The metal nanoparticle content of p(APTMAC1) microparticles were quantified for each composites by atomic absorption spectroscopy (AAS) after dissolution of the metal nanoparticles within microgel composites by concentrated hydrochloric acid (HCI). Dynamic light scattering (DIS) was used to monitor zeta potential of the microgel composites. Thermal properties of both cationic p(APTMAC1) microgel and its composites were investigated with a thermal gravimetric analyzer (TGA). It was also found that the p(APTMAC1) composites performed as excellent catalyst systems in the reduction of different aromatic pollutants like 2-nitrophenol, 4-nitrophenol and fluorescent dyes like eosin Y(EY), and methyl orange (MO). Various parameters such as metal types, and their respective amount, and temperature were investigated to determine the catalytic performances of the microgel-metal nanoparticle composites. (C) 2014 Elsevier B.V. All rights reserved.
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    Fast removal of high quantities of toxic arsenate via cationic p(APTMACl) microgels
    (Academic Press Ltd- Elsevier Science Ltd, 2016) Rehman, Saif Ur; Siddiq, Mohammed; Al-Lohedan, Hamad; Aktaş, Nahit; Şahiner, Mehtap; Demirci, Şahin; Şahiner, Nurettin
    Hydrogels are resourceful materials and can be prepared in different morphology, size, surface charge and porosity adopting different polymerization techniques and reaction conditions. The cationic poly(3-acrylamidopropyl)trimethylammonium chloride (p(APTMACl)) microgels were synthesized by photo-initiated inverse suspension polymerization technique. These microgels were utilized as absorbents for the removal of toxic arsenate (As) from different aqueous environments. The experimental parameters affecting absorption efficiency were investigated, and it was demonstrated that these types of microgels are highly efficient in removing arsenate anions from different aqueous environments compared to the previously reported bulk hydrogel, and cryogel of the same material. A removal efficiency of approximately 97.25% was obtained by immersing 0.5 g microgel in 250 ppm 100 mL solution of arsenate anions for 60 min. Both Langmuir and Freundlich adsorption isotherms were applied to adsorption of arsenate anions by p(APTMACl) microgels, and the Langmuir isotherm was a better representation of the adsorption of arsenate with a high value of R-2 (0.9982). Furthermore, mag-p(APTMACl) microgels were synthesized for the adsorption of arsenate anions to provide easy removal of the microgel composite by using an externally applied magnetic field. Furthermore, re-usability of the p(APTMACl) microgels was also investigated for the adsorption of arsenate anions. CD 2015 Elsevier Ltd. All rights reserved.
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    Synthesis and characterization of new microgel from tris(2-aminoethyl)amine and glycerol diglycidyl ether as poly(TAEA-co-GDE)
    (Elsevier, 2015) urRehman, Saif; Şahiner, Mehtap; Sel, Kıvanç; Siddiq, Mohammed; Şahiner, Nurettin
    Here, we report a new microgel preparation from tris(2-aminoethyl)amine (TAEA) and glycerol diglycidyl ether (GDE) as p(TAEA-co-GDE) via simple microemulsion polymerization/crosslinking by using L-a lecithin as surfactant and gasoline as organic phase. The p(TAEA-co-GDE) microgels were visualized using optical microscopy and scanning electron microscopy (SEM) with size ranges <10 mu m. The prepared particles were found to be positively charged, 23.61 +/- 1.2 mV at pH similar to 4.5, according to zeta-potential measurements, and the charge of particles decreased with increase in pH of the medium and become negatively charged after pH 10. The microgel particles were protonated (quaternized) or deprotanated by HCl and NaOH treatments, changing their zeta potential to 33 +/- 1.3 mV and 14.53 +/- 1.8 mV, respectively. Thermal properties of the prepared particles were observed by TG analysis before and after quaternization, and also after Co(II), Cu(II) and Cd(II) metal ion absorption. Here, we also demonstrated in situ CdS quantum dot (Q-dots) preparation within p(TAEA-co-GDE) microgels. The peak energy of 2.5 eV was observed in the fluorescence spectrum of p(TAEA-co-GDE)-CdS microgel by applying an excitation wavelength of 300 nm. Furthermore, the prepared p(TAEA-co-GDE) particles showed antibacterial characteristics against common bacteria such as Escherichia coli ATCC 8739, Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633 and Pseudomonas aeruginosa ATCC 10145 and have great potential for biomedical use. Additionally, p(TAEA-co-GDE) particles are found to be biocompatible against L929 Fibroblast cells. (C) 2015 Elsevier B.V. All rights reserved.