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Öğe Biogenic Silver Nanoparticles for Trace Colorimetric Sensing of Enzyme Disrupter Fungicide Vinclozolin(Mdpi, 2019) Hussain, Masood; Nafady, Ayman; Sirajuddin; Avci, Ahmet; Pehlivan, Erol; Nisar, Jan; Sherazi, Syed Tufail HussainWe 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.Öğe Electrospinning of polymeric nanofiber (nylon 6,6/graphene oxide) for removal of Cr (VI): synthesis and adsorption studies(Springer International Publishing Ag, 2019) Parlayici, Serife; Avci, Ahmet; Pehlivan, ErolPolymer nanofibers are valuable materials that are of great importance because they are inexpensive and they display high strength. In this study, nylon-6,6 (N6,6)/graphene oxide (GO) nanofibers were developed and characterized. GO was synthesized from graphene using the known Hummer's method. GO is obtained by reaction of the graphene with strong oxidants and was characterized using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The characterizations showed that the graphene was suitably oxidized. GO was added to N6,6 to produce N6,6/GO nanofibers at loadings of 0.5, 1.0, 1.5, and 2.0 wt% through the melt mixing method. The batch adsorption model for Cr (VI) adsorption was applied as a function of time, initial Cr (VI) concentration, adsorbent dosage, and pH to examine nanofiber activity. N6,6/GO a exhibited high adsorption capacity for Cr (VI) at pH 2.0. The maximum adsorption capacity for Cr (VI) ion was found to be 47.17 mg/g of N6.6/GO using the related isotherm curves and equations. When the equilibrium data were examined, it was concluded that Langmuir adsorption isotherm was more suitable.Öğe Electrospinning of polymeric nanofiber (nylon 6,6/graphene oxide) for removal of Cr (VI): synthesis and adsorption studies(Springer International Publishing Ag, 2019) Parlayici, Serife; Avci, Ahmet; Pehlivan, ErolPolymer nanofibers are valuable materials that are of great importance because they are inexpensive and they display high strength. In this study, nylon-6,6 (N6,6)/graphene oxide (GO) nanofibers were developed and characterized. GO was synthesized from graphene using the known Hummer's method. GO is obtained by reaction of the graphene with strong oxidants and was characterized using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The characterizations showed that the graphene was suitably oxidized. GO was added to N6,6 to produce N6,6/GO nanofibers at loadings of 0.5, 1.0, 1.5, and 2.0 wt% through the melt mixing method. The batch adsorption model for Cr (VI) adsorption was applied as a function of time, initial Cr (VI) concentration, adsorbent dosage, and pH to examine nanofiber activity. N6,6/GO a exhibited high adsorption capacity for Cr (VI) at pH 2.0. The maximum adsorption capacity for Cr (VI) ion was found to be 47.17 mg/g of N6.6/GO using the related isotherm curves and equations. When the equilibrium data were examined, it was concluded that Langmuir adsorption isotherm was more suitable.Öğe Fabrication of novel chitosan-humic acid-graphene oxide composite to improve adsorption properties for Cr(VI)(Springer Heidelberg, 2019) Parlayici, Serife; Avci, Ahmet; Pehlivan, ErolA novel chitosan-humic acid-graphene oxide (Cts-HA-GO) composite was produced and tested to remove hexavalent chromium (Cr(VI)) during the adsorption process. The percentage adsorption was 85.28% by using 200 ppm Cr(VI) and 2 g/L composite. Four hours of contact time was enough to remove Cr(VI) from the aquatic medium. The extent of adsorption of Cr(VI) on the surface of Cts-HA-GO composite was examined on the basis of increasing quantity of the composite. The functional group characterization and morphology of composite was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. After reaching the equilibrium, the residual concentration of the Cr(VI) solution was measured with an UV-visible spectrophotometer. The results showed that the adsorption behaviour was in accordance with the Langmuir isotherm model, and the maximum adsorption capacity of Cr(VI) determined by using this model was 83.64 mg/g at the pH of 2. A pseudo-second-order model equation has justified the equilibrium between Cr(VI) and the composite for the kinetic studies.Öğe Novel sandwiched composite electro-spun mats based on polyacrylonitrile and polyvinyl butyral for fast oil-water separation(Springer, 2019) Kahraman, Havva Tutar; Avci, Ahmet; Pehlivan, ErolIn recent years, the issue on oil pollution in water has drawn continuous attention of researchers. Wastewater containing oil is generated in various industrial technologies, such as petrochemical, leather, textile, food, steel, and metal-finishing industries. Thus, oil sorbents are very commonly used during oil spills cleanup operation for their cost-effectiveness and affordability. In the present work, a novel sandwiched composite electro-spun nanofibrous mat (SCEM) was generated by electro-spinning technique. This sandwiched composite electro-spun mat was fabricated by sandwiching the chitosan-incorporated polyvinyl butyral nanofiber mat between two layers of polyacrylonitrile electro-spun mats. Surface morphology of the generated multilayer nanofibrous mat was observed by the static water contact angle measurement, SEM and FTIR analyses. SCEM was modified by alcoholysis reaction to increase the hydrophobicity and oleophilicity properties by enhancing the surface roughness. After fabrication and modification processes, oil-absorption capacities of single mats, SCEM, and modified mat designated as M-SCEM were investigated and calculated in terms of weight gains. Mats with sandwich structure exhibited excellent absorption capacities up to 100-140 times their own weight for motor oil. The obtained results suggest that these characteristics make spun bond nanofibrous mat a promising oil sorbent material for efficient oily water remediation.Öğe Synthesis of novel metal/bimetal nanoparticle-modified ZSM-5 zeolite nanocomposite catalysts and application on toluene methylation(Springer, 2022) Niftaliyeva, Aysel; Karaduman, Ali; Kalwar, Nazar Hussain; Avci, Ahmet; Pehlivan, ErolSynthesis of Ag, Ni, Cu metallic and Ag/Ni, Ag/Cu bimetallic nanoparticles (NPs) was carried out by using metal nitrate salts as precursors via an easy and simple wet chemical method, and the synthesized NPs were loaded into the cavities of ZSM-5 zeolite framework. L-threonine was used as a capping agent and sodium borohydride as a reducing agent. Characterization of NPs and nanoparticle-modified ZSM-5 catalysts were realized with TEM, XRD, BET, FTIR, TGA, etc. The results obtained revealed that the structure of the zeolites was well preserved after the modification with metal NPs. According to the TEM and BET results, Ag-containing nanocomposite catalysts increased average pore diameter due to the small particle size of Ag NPs such as 2-6 nm well dispersed on the surface and partial blockage of the micropores of zeolite. The catalytic activity of the prepared catalysts was tested in toluene methylation at temperatures of 300 degrees C, 400 degrees C, 500 degrees C and different weight hourly space velocities (WHSV). At low temperatures, the modification of NPs in the ZSM-5 matrix increased toluene methylation and p-xylene selectivity. The highest p-xylene selectivity was found to be about 51% at 400 degrees C, while toluene conversion at this temperature was 61% using Ag NP-modified ZSM-5 due to the perfect stability NPs on the zeolite structure. The XRD, TGA and coke formation results of used catalysts show the reusability of these catalysts due to their thermal resistance, minimal coke formation and Ag NPs stability onto the zeolite framework.Öğe ZnO-TiO2 doped polyacrylonitrile nano fiber-Mat for elimination of Cr (VI) from polluted water(Springer International Publishing Ag, 2019) Parlayici, Serife; Yar, Adem; Pehlivan, Erol; Avci, AhmetPAN nanofiber-Mat (n-fib@Mat), PAN/ZnO n-fib@Mat, and PAN/ZnO-TiO2 n-fib@Mat were prepared via electrospinning method. Their high adsorption capacities against dissolved Cr (VI) ions make them as super adsorbents for water treatment The structure of n-fib@Mat was investigated using XRD, FTIR, SEM, and TEM techniques. The effects of selected parameters such as contact time, initial concentration, and n-fib@Mat amount were assessed in a fixed bed reactor. It was found that the adsorption capacities of PAN n-fib@Mat, PAN/ZnO nfib@Mat, and PAN/ZnO-TiO(2)n-fib@Mat were pH-dependent and the optimal pH value was between 2.1 and 2.2. The adsorption was rapid, and the equilibrium was reached within 240 min to remove of Cr (VI) ions for PAN/ZnOTiO2 n-fib@Mat and 360 min for PAN n-fib@Mat and PAN-ZnO n-fib@Mat. Langmuir isotherms model is preferred for PAN n-fib@Mat, PAN-ZnO n-fib@Mat, and PAN/ZnO-TiO2 n-fib@Mat for Cr (VI) adsorption. The equilibrium adsorption capacities are 153.85 mg/g, 234.52 mg/g, and 333.43 mg/g for PAN n-fib@Mat, PAN/ZnO n-fib@Mat, and PAN/ZnO-TiO(2 )n-fib@Mat for Cr (VI), respectively. The produced n-fib@Mat showed excellent removal ability for Cr (VI). The adsorption kinetic was obeyed pseudo-second-order reaction rate.Öğe ZnO-TiO2 doped polyacrylonitrile nano fiber-Mat for elimination of Cr (VI) from polluted water(Springer International Publishing Ag, 2019) Parlayici, Serife; Yar, Adem; Pehlivan, Erol; Avci, AhmetPAN nanofiber-Mat (n-fib@Mat), PAN/ZnO n-fib@Mat, and PAN/ZnO-TiO2 n-fib@Mat were prepared via electrospinning method. Their high adsorption capacities against dissolved Cr (VI) ions make them as super adsorbents for water treatment The structure of n-fib@Mat was investigated using XRD, FTIR, SEM, and TEM techniques. The effects of selected parameters such as contact time, initial concentration, and n-fib@Mat amount were assessed in a fixed bed reactor. It was found that the adsorption capacities of PAN n-fib@Mat, PAN/ZnO nfib@Mat, and PAN/ZnO-TiO(2)n-fib@Mat were pH-dependent and the optimal pH value was between 2.1 and 2.2. The adsorption was rapid, and the equilibrium was reached within 240 min to remove of Cr (VI) ions for PAN/ZnOTiO2 n-fib@Mat and 360 min for PAN n-fib@Mat and PAN-ZnO n-fib@Mat. Langmuir isotherms model is preferred for PAN n-fib@Mat, PAN-ZnO n-fib@Mat, and PAN/ZnO-TiO2 n-fib@Mat for Cr (VI) adsorption. The equilibrium adsorption capacities are 153.85 mg/g, 234.52 mg/g, and 333.43 mg/g for PAN n-fib@Mat, PAN/ZnO n-fib@Mat, and PAN/ZnO-TiO(2 )n-fib@Mat for Cr (VI), respectively. The produced n-fib@Mat showed excellent removal ability for Cr (VI). The adsorption kinetic was obeyed pseudo-second-order reaction rate.
