Browsing by Author "Yildiz, Adnan"

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Determination of the Optimum Conditions for Boric Acid Extraction From Ulexite in Perchloric Acid Solutions
(Asian Journal of Chemistry, 2008) Gur, Aycan; Yildiz, Adnan; Celik, Hilal; Selcuk, Ahmet
In this study, Taguchi method was used to determine optimum conditions for the dissolution of ulexite in perchloric acid slutions. For optimization process; solid-to-liquid ratio, reaction time, particle size and acid concentration were chosen as parameters. In the experiment, stirring speed and reaction temperature were kept as constant. The ranges of experimental parameters-were between 0.1-0.2 g/cm(3) for solid-to-liquid ratio, 1.5-2.5 M for acid concentration, 165.0-512.5 mu m for particle size and 12-36 min for reaction time. In the end of the experimental sections the optimum conditions were determined as 0.1 g/mL for solid to liquid ratio; 215 mu m for particle size; 24 min for reaction time; 500 rpm for stirring speed; 30 degrees C for reaction temperature and 2 mol/dm(3) for acid concentration. Under these conditions, it was found that the boric acid extraction from ulexite was reached a value of 99 %.
Dissolution Kinetics and Mechanism of Pandermite in Acetic Acid Solutions
(Academic Journals, 2010) Gur, Aycan; Caglayan, Firat; Yildiz, Adnan; Selcuk, Ahmet
In this study, the dissolution kinetics and mechanism of pandermite mineral was investigated using a batch reactor employing the parameters of particle size, acid concentration, solid/liquid ratio, stirring speed and reaction temperature. From experimental data, it was determined that the conversion rate of pandermite to boric acid was increased with decreasing particle size, solid/liquid ratio and increasing reaction temperature. Conversion rate increased up to 3 M, acid concentration then decreased with increasing acid concentration. It was observed that there was no important effect of stirring speed on the dissolution rate. Furthermore, it was observed that the dissolution mechanism was dependent on acid concentration due to restriction of dissolution in acetic acid solutions. The dissolution rate of pandermite mineral in acetic acid solution was examined according to homogeneous and heterogeneous chemical reaction model. It was determined from graphical and statistical methods that the reaction kinetics fitted to model in the form of first order pseudo homogeneous model [- ln (1 - X)] = kt and activation energy for the dissolution process was found to be 28.496 kj/mol. A mathematical model, which indicated the dissolution process was established.
In Situ Preparation of Tio2/F-mwcnt Catalyst Using Pluronic F127 Assisted Sol-Gel Process for Sonocatalytic Degradation of Methylene Blue
(Academic Press inc Elsevier Science, 2023) Yildiz, Adnan; Yesilbas, Omer Faruk; Nas, Mehmet Salih; Calimli, Mehmet Harbi; Bayat, Ramazan; Sen, Fatih
In this study, titanium dioxide-Pluronics @F127/functionalized-multi walled carbon nanotubes (TiO2-F127f-/ MWCNT) nanocatalysts were prepared, characterized, and used in methylene blue (MB) degradation under ul-trasonic conditions. The characterization studies were performed using TEM, SEM, and XRD analyses to reveal the morphological and chemical properties of TiO2-F127/MWCNT nanocatalysts. To detect the optimum pa-rameters for MB degradation using TiO2-F127/f-MWCNT nanocatalysts, several experimental parameters were conducted at various conditions such as different temperatures, pH, catalyst amount, hydrogen peroxide (H2O2) concentration, and various reaction contents. Transmission electron microscopy (TEM) analyses showed that TiO2-F127/f-MWCNT nanocatalysts consisted of a homogenous structure and have a 12.23 nm particle size. The crystalline particle size of TiO2-F127/MWCNT nanocatalysts was found to be 13.31 nm. Scanning electron microscope (SEM) analyses revealed the surface structure of TiO2-F127/f-MWCNT nanocatalysts turned to be modified after TiO2 loaded on MWCNT. Under the optimum conditions; pH: 4, MB concentration: 25 mg/L, H2O2 concentration: 30 mol/L, reaction time: and catalyst dose: 24 mg/L, chemical oxygen demand (COD) removal efficiency reached a maximum of 92%. To detect the radical effectiveness, three scavenger solvents were tested. Reuse experiments revealed that TiO2-F127/f-MWCNT nanocatalysts retained 84.2% catalytical activity after 5 cycles. Gas chromatography-mass spectrometry (GC-MS) was successfully used to identify the generated in-termediates. Based on the experimental results, it has been suggested that center dot OH radicals are the main active species responsible for the degradation reaction in the presence of the TiO2-F127/f-MWCNT nanocatalysts.
Pdruo2/Pvp Nanomaterial as a Highly Selective, Stable, and Applicable Potentiometric Sensor for the Detection of Cr3+
(Springer Wien, 2024) Cevik, Kenan; Yildiz, Ilyas; Yildiz, Adnan; Nas, Mehmet Salih; Alma, Mehmet Hakki; Calimli, Mehmet Harbi
PdRuO2/PVP nanomaterial was synthesized using a straightforward method and characterized using advanced analytical methods such as TEM, XRD, XPS, elemental mapping and SEM. The synthesized PdRuO2/PVP nanomaterial was used as an ionophore in potentiometric sensor electrodes and successfully adapted to Cr3+ ion detection in a large number of aqueous samples. Several experimental parameters of the PdRuO2/PVP sensor such as potentiometric behavior, selectivity, repeatability, response time, pH, titration, and recovery in real samples were investigated. Potentiometric behavioral characteristics were performed in the concentration range 1 x 10(-6)-1.0 x 10(-1) M. The repeated experiments performed six times showed that there was no deviation in the measurements. The limit of detection of the PdRuO2/PVP potentiometric sensor was very low with a value of 8.6 x 10(-8) M. The potentiometric measurements showed that the synthesized PdRuO2/PVP ionophore was highly effective in detecting Cr3+ in a wide pH range of 2.0-8.0 and was found to have a shelf life of over 1 year. As a result, the synthesized PdRuO2/PVP electrode material was found to be highly selective, stable, and applicable for Cr3+ detection.
Synthesis, Characterization, and Utilization of Niceo2@f-mwcnt/Eda Nanoparticles as Electrode Materials for Supercapacitor Application
(Pergamon-elsevier Science Ltd, 2023) Yildiz, Adnan; Demirel, Serkan; Nas, Mehmet Salih; Calimli, Mehmet Harbi
Metal oxide and carbon nanotube-based materials are widely preferred in supercapacitor and electrochemical sensor applications due to their interesting physicochemical structure. In this paper, we report the synthesis, characterization, and utilization of NiCeO2@f-MWCNT/EDA nanoparticles as electrode materials for supercapacitor applications. The characterization studies of NiCeO2@f-MWCNT/EDA nanomaterials were performed using X-ray diffraction (XRD), Transmission electron microscope (TEM), and Raman spectroscopy apparatus. The characterization methods revealed a good distribution of NiCeO2 on f-MWCNT/EDA and formed a new structure of NiCeO2@f-MWCNT/EDA nanoparticles. Electrochemical studies of NiCeO2@f-MWCNT/EDA nanoparticles showed a significant specific capacitance of between 2385 and 603 Fg  1 with good cyclic stability of 1000 cycles with capacity retention between 42% and 1.4% at 10 mV/s scan rate. The obtained results reveal that the prepared NiCeO2@f-MWCNT/EDA nanoparticles are promising electrode materials for supercapacitor devices.