Browsing by Author "Akkus, Ihsan Nuri"

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Cross-Linked Poly(styrene-Co Quartz and Kaolinite Proppants for Hydraulic Fracturing Applications
(Springer Heidelberg, 2025) Akkus, Ihsan Nuri; Akinay, Yuksel; Zengin, Adem; Kazici, Hilal celik
The hydraulic fracturing operation, used as a production process in shale gas and coalbed methane reservoirs in the oil and natural gas industry, consists of fracturing fluid, proppant, and many other chemicals. This study successfully produced hydraulic fracturing proppants based on quartz and kaolinite minerals using divinyl benzene cross-linked styrene polymer with an in situ suspension polymerization method. Morphological analysis of the prepared proppants confirmed their spherical structure and the sphericity of quartz and kaolinite proppants were determined as 0.9. The polymer shells of the prepared proppants showed thermal resistance up to 375 degrees C and then decomposed between 375 degrees C and 575 degrees C. As a result of mechanical tests, quartz proppants showed a crush resistance of 14.08% under a load of 18,000 psi. Similarly, a crush resistance of 14.28% for kaolinite proppants was determined under a load of 15,000 psi. The apparent densities of quartz and kaolinite proppants were determined as 1.635 g/cm3 and 1.365 g/cm3, respectively. However, quartz proppants mostly display brittle breakage behavior, while kaolinite proppants are plastically deformed under the applied load.
The Electromagnetic Wave Absorption Properties of Woven Glass Fiber Composites Filled With Sb2o3 and Sno2 Nanoparticles Doped Mica Pigments
(Wiley, 2022) Akinay, Yuksel; Colak, Bektas; Turan, Muhammet Emre; Akkus, Ihsan Nuri; Kazici, Hilal Celik; Kizilcay, Abdullah Oguz
In this study, the electromagnetic wave absorption properties of woven glass fiber reinforced epoxy composites with Sb2O3 and SnO2 nanoparticles doped mica pigments were investigated. Herein, we synthesized SnO2/mica, Sb2O3/mica, and Sb2O3:SnO2/mica pigments using the sol-gel method. Subsequently, mica pigments filled glass fiber/epoxy composite panels were fabricated with a vacuum assisted resin mold. The phase, crystal, and morphological examinations of particles confirm the deposition of SnO2 and Sb2O3 nanoparticles on the mica surfaces. The electromagnetic wave absorption properties of samples were measured using the S parameters and obtained dielectric data. Sb2O3:SnO2/mica particles display higher complex permittivity and dielectric loss values due to the strong interfacial polarization between conductive nano metal-oxide shells and mica surfaces. According to the calculated reflection loss values, Sb2O3:SnO2/mica particles exhibit superior electromagnetic wave absorption performance with a minimum reflection loss of -25.62 dB for 2.4 mm thicknesses with effective bandwidth between 9.3 and 12.4 GHz. The S parameters of the prepared structural composites with the size of 30 cm x 30 cm x 3 mm was determined by the free-space technique using the transmission line technique. According to the S-12 parameters, filled glass fiber/epoxy composite containing 25 wt% Sb2O3:SnO2/mica show a minimum reflection loss of -20.426 dB at 8.2 GHz with effective bandwidth between 8.2 and 9.67 GHz. These results indicate that Sb2O3:SnO2/mica-filled fiber/epoxy composite is an excellent candidate for the practical application of electromagnetic wave absorbers.
Rh (0) Nanoparticles Impregnated on Two-Dimensional Transition Metal Carbides, Mxene, as an Effective Nanocatalyst for Ammonia-Borane Hydrolysis
(Wiley, 2022) Karatas, Yasar; Cetin, Tayfun; Akkus, Ihsan Nuri; Akinay, Yuksel; Gulcan, Mehmet
MXene, which are known as two-dimensional transition metal carbides have received heavy interest due to their rich elemental diversity and many fascinating physical and chemical properties. Here, Rh (0) nanoparticles deposited MXene catalysts were synthesized by an easy wet-impregnation method for hydrogen production. Rh (0) nanoparticles were conveniently loaded on the surface of MXene (Rh/MXene) were used as an effective nanocatalyst for the hydrogen production from the hydrolysis of ammonia-borane (AB). The morphological and structural characterizations of Rh/MXene catalysts show that Rh nanoparticles were successfully deposited on the surface of MXene substrates. Rh (0) nanoparticles with an average size of 2.55 nm were homogeneously dispersed and deposited on the MXene surface. The Rh/MXene displayed good catalytic performance in the hydrogen production via the hydrolysis of AB, and the turnover frequency value at 25 degrees C was 288.4 min(-1), which is comparable to most of the synthesized catalysts. The Rh/MXene catalyst displaying good activity in seven consecutive catalytic cycles can be considered a good nanocatalyst candidate for hydrogen production from the hydrolysis of AB.
Synthesis and Characterization of the Pearlescent Pigments Based on Mica Deposited With Sio2, Aln and Tio2: First Report of Its Dielectric Properties
(Elsevier Sci Ltd, 2020) Akinay, Yuksel; Akkus, Ihsan Nuri
SiO2, AlN and TiO2 deposited mica based pearlescent pigments were synthesized by using the chemical reduction method in aqueous solution. The optical and dielectric properties of mica@SiO2, mica@AlN, and mica@TiO2 were investigated. The comprehensive analysis of the obtained pigments was evaluated by determining their thermal, optic and dielectric properties. The surface structure, bonding, and phase properties were obtained by field emission scanning electron microscope (FESEM), Fourier-transform infrared spectroscopy (FTIR), and x-ray diffraction (XRD), respectively. The thermal and optical properties were determined by thermogravimetric analysis (TGA) and UV-vis absorbance spectra. For the first time, the dielectric and electromagnetic wave absorption properties of pearlescent pigments were investigated. The mica@TiO2 pigment exhibited higher UV-vis absorption than those of mica@SiO2, and mica@AlN. Besides, the presence of TiO2 has tremendously increased the dielectric values. The electromagnetic (EM) wave absorption of mica@TiO2 achieved a minimum R-L, value of -16.7 dB at a thickness of 3.4 mm. This study presented a new report for dielectric and EM absorption of mica@SiO2, mica@AlN, and mica@TiO2 pigments.
Synthesis of 3d Sn Doped Sb2o3 Catalysts With Different Morphologies and Their Effects on the Electrocatalytic Hydrogen Evolution Reaction in Acidic Medium
(Elsevier Sci Ltd, 2021) Akinay, Yuksel; Kazici, Hilal Celik; Akkus, Ihsan Nuri; Salman, Firat
Recently, the design and synthesis of highly effective, abundant and low-cost catalysts to produce molecular hydrogen through the hydrogen evolution reaction (HER) have been studied in a wide range of pHs to replace Pt. In this work, 3D flower-like and rod-like pure Sb2O3 and Sn: Sb2O3 particles by using co-precipitation methods were efficiently synthesized for electro-catalytic energy conversion applications. The morphologies and structure of the synthesized catalysts were investigated extensively. Electrochemical studies were carried out to investigate the catalytic performance of 3D flower-like and rod-like Sn: Sb2O3 and pure Sb2O3 particles for hydrogen evolution reactions (HER) in acidic environments using 0.5 M H2SO4 electrolyte. Among the prepared particles, 3D rod-like Sn: Sb2O3 show excellent electro-catalytic hydrogen evolution reactions (HER) at 0.5 M H2SO4. Moreover, we have obtained the high stability of the electrodes during chronoamperometric studies (current v/s time) approximately 2000 s at constant potential.