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    Biogenic silver nanoparticles for trace colorimetric sensing of enzyme disrupter fungicide vinclozolin
    (MDPI, 2019) Hussain, Masood.; Nafady, Ayman.; Sirajuddin.; Avcı, Ahmet.; Pehlivan, Erol.; Nisar, Jan.; Sherazi, Syed Tufail Hussain.; Balouch, Aamna.; Shah, Muhammad Raza.; Almaghrabi, Omar A.; Ul-Haq, Muhammad Anwar.
    We report a novel, simple, efficient, and green protocol for biogenic synthesis of silver nanoparticles (AgNPs) in aqueous solution using clove (Syzygium aromaticum) extract as a reducing and protecting agent. Ultraviolet-visible (UV-Vis) spectroscopy was employed to monitor the localized surface plasmon resonance (LSPR) band of clove extract-derived AgNPs prepared under various conditions. Fourier-transform infrared (FTIR) spectroscopy analysis provided information about the surface interaction of the clove extract with the AgNPs. Ultrahigh-resolution transmission electron microscopy (UHRTEM) results confirmed the formation of spherical, uniformly distributed clove extract-capped AgNPs with sizes in the range of 2-20 nm (average size: 14.4 +/- 2 nm). Powder X-ray diffractometry analysis (PXRD) illustrated the formation of pure crystalline AgNPs. These AgNPs were tested as a colorimetric sensor to detect trace amounts of vinclozolin (VIN) by UV-Vis spectroscopy for the first time. The AgNP-based sensor demonstrated very sensitive and selective colorimetric detection of VIN, in the range of 2-16 mu M (R-2 = 0.997). The developed sensor was green, simple, sensitive, selective, economical, and novel, and could detect trace amounts of VIN with limit of detection (LOD) = 21 nM. Importantly, the sensor was successfully employed for the determination of VIN in real water samples collected from various areas in Turkey.
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    Inorganic acid doped highly hydroxylated polymer based thin membrane
    (ELSEVIER, 2019) Radha, Morad Abdulwheed.; Şahin, Alpay.; Pehlivan, Erol.; Ar, İrfan.
    The effects of phosphoric acid (p) on the polyvinyl alcohol (PVA) as highly hydroxyl-group content polymer have been investigated. Functionalized membranes (p-PVA) have been prepared via sol-gel method with different doped acid ratios. Fourier Transform Infrared (FTIR) spectroscopy is used to confirm the structure of the pure polymer and the synthesized membrane. Water uptake capacity, plane swelling, thickness swelling, proton conductivity by electrochemical impedance spectroscopy (EIS) and thermal stability by thermal gravimetric analysis (TGA) are used to characterize the membranes for their applications in the suitable engineering fields. The results showed that the doped acid has suppressed effects on the hydrophilic properties of the used polymer which leads to decreasing in the water uptake and swelling properties of membranes. Thermally cross-linked 30% p-PVA thin membrane was selected because of its good water uptake capacity (43.78%) and low swelling degree (21.07%). The proton conductivity of all membrane increased with increasing the temperature up to 60 degrees C for 30% p-PVA thin membrane and it attained to 0.07 S cm(-1). The proton conductivity decreased to 0.013 S cm(-1) at the same temperature for 40% p-PVA thin membrane. The thermal stability of doped polymer membranes is significantly higher than pure hydroxylated polymer which indicates the strong bonding between the doped acid and polymer. (C) 2019 Elsevier Ltd. All rights reserved.
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    Removal of chromium(VI) from aqueous solution using chitosan doped with carbon nanotubes
    (ELSEVIER, 2019) Parlayıcı, Şerife.; Pehlivan, Erol.
    This work investigates the adsorption of chromium ions on chitosan doped with multiwalled carbon nanotubes (Cht-MWCNT). The effects of initial pH, amount of Cht-MWCNT, temperature, contact time, and the initial concentration of Cr (VI) were investigated during the equilibrium and kinetic studies. The equilibrium time was found to be 60 min. Adsorption isotherms of Cr (VI) on Cht-MWCNT was determined and correlated with Langmuir, Freundlich, Scatchard and D-R isotherm equations. The adsorption data showed that adsorption of Cr (VI) was fitted by Langmuir isotherm model and pseudo-second-order kinetics model. Under optimum conditions, maximum adsorption capacity of Cr (VI) determined by Langmuir model were enhanced 26.14 mg/g. Thermodynamic parameters such as Delta G degrees, Delta H degrees, Delta S degrees were calculated and the interaction of Cr (VI) with Cht-MWCNT was found to be endothermic and spontaneous in nature. (C) 2019 Elsevier Ltd. All rights reserved.