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Öğe 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.Öğe 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.Öğe Effect of doping on thin film solar cell efficiency based on ZnMn2O4 nanocrystals(ELSEVIER, 2019) Sarılmaz, Adem; Özel, Faruk; Aljabour, Abdalaziz; Khaskheli, Abdul Rauf; Kuş, MahmutThe present study reports, for the first time, a facile synthesis for ternary ZnMn2O4 nanocrystals synthesized by a simple and low cost two-phase method. Those nanocrystals were used on thin film solar cell as active absorber layer. The resulting nanocrystals were characterized by XRD, TEM, AFM-MFM, FTIR and JV characterization techniques to investigate the crystalline behavior, chemical composition, morphology and optical properties. Two phase method allows the successful synthesis of oleic acid (OA) capped ZnMn2O4 nanocrystals with 5-10 nm particle size. After doping of the ZnMn2O4 nanocrystals at different ratios with P3HT:PCBM, an enhancement was observed in the solar cell performances based on thin films. The power conversion efficiency of P3HT:PCBM-ZnMn2O4 thin film solar cell was investigated by J-V characteristic curve and as a result of this study, the highest efficiency was achieved as 3.27% with a doping ratio of 1%. Thus we believe that this work will open a new perspective to the synthesis of ZnMn2O4 materials for applications in the field of energy conversion systems. (C) 2019 Elsevier Ltd. All rights reserved.
