Sebahattin Gürmen

Production and characterization of ZnO nanoparticles and porous particles by ultrasonic spray pyrolysis using a zinc nitrate precursor

ZnO nanoparticles and porous particles were produced by an ultrasonic spray pyrolysis method using a zinc nitrate precursor at various temperatures under air atmosphere. The effects of reaction temperature on the size and morphology of ZnO particles were investigated. The samples were characterized by energy dispersive spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. ZnO particles were obtained in a hexagonal crystal structure and the crystallite shapes changed from spherical to hexagonal by elevating the reaction temperature. The crystallite size grew by increasing the temperature, in spite of reducing the residence time in the heated zone. ZnO nanoparticles were obtained at the lowest reaction temperature and ZnO porous particles, formed by aggregation of ZnO nanoparticles due to effective sintering, were prepared at higher temperatures. The results showed that the properties of ZnO particles can be controlled by changing the reaction temperature in the ultrasonic spray pyrolysis method.

Beneficiation of brass ashes

Abstract Slags formed during brass smelting contain a significant amount of metallic value. The glassy and oxidized portion of the ground slag, usually referred to as “brass ash”, consists of compounds such as ZnO, ZnO·SiO 2 , Cu-Zn, CuO, Cu and Zn/Cu/B oxide, and its colored-metal content may vary between 28÷52% Zn and 8÷16% Cu. These ashes are classified as harmful wastes, due to their high Zn content, and are considered to be secondary raw materials that should be treated accordingly, from an economical viewpoint. The aim of this experimental study is to investigate the possibilities of beneficiating brass ashes by treating it with H 2 SO 4 or (NH 4 ) 2 CO 3 + NH 4 OH mixtures. Effects of temperature, air sparging and addition of oxidizing agents, such as MnO 2 and Fe 2 (SO 4 ) 3 , are investigated on copper and zinc leaching recovery. As a result of both acidic and alkaline leaching experiments, it is observed that more than 90% of Zn and more than 65% of Cu was leached out. Two separate process flow sheets are proposed for the possible treatment of brass ashes.

Production of nanocrystalline silver particles by hydrogen reduction of silver nitrate aerosol droplets

Nanocrystalline silver particles were produced by hydrogen reduction of silver nitrate aerosol droplets formed by high frequency ultrasonic generator. The dependences of the particle size, morphology and crystallite size on the precursor concentration and the reaction temperature were investigated. Ultrasonic spray pyrolysis process was combined with hydrogen reduction to research the effects on the silver particle production. Nanocrystalline silver particles including slight oxide structure were prepared at temperature as low as 200 °C from silver nitrate under hydrogen atmosphere. X-ray diffraction (XRD) studies showed that pure silver particles were obtained above 200 °C reaction temperature. The crystallite sizes of the samples ranged from 29 to 47 nm. The results indicate that the crystallite sizes hardly ever depended on the reaction temperature. Crystallites slightly enlarged by increasing precursor concentration. SEM observations showed that particles were obtained in spherical morphology with particle sizes between

Estimation of yttrium oxide microstructural parameters using the Williamson–Hall analysis

ABSTRACT Yttrium oxide (Y2O3) particles were synthesised from a yttrium nitrate solution via ultrasonic spray pyrolysis (USP) method. The effects of temperature and precursor concentration on morphology and microstructural parameters were investigated. Y2O3 particles were characterised by scanning-electron-microscope energy-dispersive spectroscopy, Raman spectroscopy and X-ray diffraction analysis. Based on X-ray peak broadening, the crystallite size was calculated using the modified Debye–Scherrer (MDS) method. Furthermore, the crystallite size, crystal strain and the energy density of the crystal were evaluated using the Williamson–Hall (W–H) analysis integrated with the uniform deformation model, the uniform stress deformation model and the uniform deformation energy density model. A comparative evaluation of Y2O3 crystallite size using the MDS and W–H methods was carried out. This is part of a thematic issue on Nanoscale Materials Characterisation and Modeling by Advances Microscopy Methods - EUROMAT.

Preparation and magnetic characterization of Fe/metal oxide nanocomposite particles by means of hydrogen reduction assisted ultrasonic spray pyrolysis (USP-HR)

Abstract Fe/metal oxide nanocomposite particles were produced by means of hydrogen reduction assisted ultrasonic spray pyrolysis. Fe/Fe0.761Mg0.239O and Fe/MgO nanocomposite particles were obtained at 600 and 800 °C, respectively. The thermodynamics of the formation reactions were investigated. Increasing the reaction temperature allowed efficient reduction of the precursor to metallic iron that induces the formation of pure MgO phase. The crystallite sizes of the Fe in the composite structures slightly increased, and also the crystallite sizes of the oxides decreased with elevating temperature. The nanocomposite particles exhibited spherical morphology and their particle sizes were slightly different. All of the samples showed ferromagnetic characteristics and the results indicate that the amount of metal and metal oxide phases most affected the saturation magnetizations of the composite particles which were lower than pure iron.

Simple preperation of CuO nanoparticles and submicron spheres via ultrasonic spray pyrolysis (USP)

Abstract Copper oxide nanoparticles and submicron size spheres were produced via the ultrasonic spray pyrolysis method using copper nitrate without any additives. The effects of the process temperature and solution concentration on the copper oxide particles were investigated. HSC software, differential scanning calorimetry and thermal gravimetric analysis were used for the thermodynamic investigation of the CuO formation by the decomposition reaction. Particle characterization studies were performed using X-ray diffraction, energy dispersive spectroscopy, scanning–and transmission–electron microscopy. The results show that spherical CuO nanoparticles having around 80 nm particle size were prepared at 400 °C and the submicron size CuO spheres were obtained by the aggregation of nanoparticles at elevated temperatures. The crystallite sizes of the particles ranged between 21 and 46 nm.

Production and characterization of submicron hematite (α−Fe2O3) particles by ultrasonic spray pyrolysis method

The ultrasonic spray pyrolysis (USP) method has been used to prepare submicron hematite (α−Fe2O3) particles using two different industrial pickling solutions of iron chloride (41 g/L FeCl2 and 54 g/L FeCl3) Particles were obtained by thermal decomposition of generated aerosols from precursor solutions using 1.7 MHz ultrasonic atomizer. Reaction temperature was set up at 800 °C and aerosol droplets were carried into the heated zone by 0.7 L/min air flow rate. X-Ray Diffraction (XRD) studies were used to determine the crystal structure and crystallite size of the particles. Results indicate that patterns correspond to hematite phase with rhombohedral crystal structure (space group: R3c). The crystallite sizes of particles prepared from FeCl2 and FeCl3 solutions that were calculated from Scherrer equation are 59 and 33 nm, respectively. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) investigations give detailed information about particle size, morphology and composition. SEM micr...

Tuning the Morphology of ZnO Nanostructures with the Ultrasonic Spray Pyrolysis Process

Nanostructured zinc oxide (ZnO) particles were synthesized by the one step Ultrasonic Spray Pyrolysis (USP) process from nitrate salt solution (Zn(NO3)2·6H2O). Various influential parameters, from Zn(NO3)2·6H2O concentrations (0.01875–0.0375 M) in the initial solution, carrier gas (N2) flow rates (0.5–0.75 L/min) to reaction temperature (400–800 ◦C), were tested to investigate their role on the final ZnO particles’ morphology. For this purpose, Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM) and (Selected Area Electron Diffraction) SAED techniques were used to gain insight into how the ZnO morphology is dependent on the USP process. It was revealed that, by certain parameter selection, different ZnO morphology could be achieved, from spherical to sphere-like structures assembled by interwoven nanoplate and nanoplate ZnO particles. Further, a more detailed crystallographic investigation was performed by XRD and Williamson-Hall (W-H) analysis on the ZnO with unique and non-typical planar morphology that was not reported before by USP synthesis. Moreover, for the first time, a flexible USP formation model was proposed, ending up in various ZnO morphologies rather than only ideal spheres, which is highly promising to target a wide application area.

Oxidative degradation of Bisphenol A by carbocatalytic activation of persulfate and peroxymonosulfate with reduced graphene oxide

In the present study, novel metal-free activation of persulfate (PS) and peroxymonosulfate with reduced graphene oxide (rGO) was investigated to degrade Bisphenol A (BPA), one of the most important endocrine disrupting compounds, from different aqueous matrices, namely distilled water (DW) and municipal wastewater treatment plant effluent (TWW). The home-made rGO was characterize and the effect of oxidant (PS and PMS) and catalyst (rGO) concentrations on BPA degradation rates in DW and TWW samples was examined. Complete BPA degradation occurred in DW and TWW with the PS/rGO treatment system after 10 min and 30 min, respectively, whereas 94% (DW) and 83% (TWW) BPA removals were obtained with PMS/rGO for the same treatment period (BPA = 2 mg/L; rGO = 0.02 g/L; PS = 0.25 mM; PMS = 0.5 mM). The radical quenching experiments demonstrated that the SO4- predominated in the activation of PS and PMS with rGO for BPA removal, however, HO contributed to the catalytic oxidation process but to a lower extend. The reusability test results, where the catalyst was deactivated seriously just after second cycle, highlighted the need for further studies to enhance the stability of rGO. This study represented an environmentally benign and efficient oxidative treatment of BPA along with insights into the rGO activated PS or PMS processes.

Production of NiO/ZnO Nanocomposite Particles by Sol-Gel Technique

Alınma: 10.01.2018 Kabul: 13.03.2018 Son yıllarda yeni nesil ve kritik malzemelere duyulan ihtiyaç, nano boyutlu malzemeleri modern araştırmaların odağına taşımıştır. Bu çalışmada, petrokimya ve enerji sektöründeki kullanımına yönelik olarak NiO/ZnO nanokompozit partiküllerin sol-jel yöntemiyle üretimi araştırılmıştır. Yüksek safiyetteki nikel nitrat [Ni(NO3)2.6H2O] ve çinko nitrat [Zn(NO3)2.6H2O] tuzlarından molce % (50:50) ve % (30:70) hazırlanan 0,1 M konsantrasyona sahip başlangıç çözeltilerinde farklı çöktürme reaktifleri (1 M NaOH; NH4OH) ve şelat yapıcının (0,1 M C6H8O7) birlikte kullanılmasıyla başlayan üretim sürecinin son adımındaki kalsinasyon işlemi (700 °C, 2 saat) ile NiO/ZnO nanokompozit partikülleri üretilmiştir. NiO/ZnO nanokompozit partiküllerinin yapısal karakterizasyon çalışmaları kapsamında; X-ışınları faz analizi (XRD, Rigaku), partiküllerin boyut-morfolojilerinin ve bileşimin kalitatif olarak tanımlanması için taramalı elektron mikroskobu ve enerji dağılım spektroskopisi (FEG SEM-EDS, Jeol) ve yapıda var olan bağların tespiti için Fourier dönüşümlü kızılötesi spektrometre (FTIR) teknikleri kullanılmıştır. Sol-gel yönteminde, başlangıç çözeltisinin stokiometrisi ile üretim aşamasında kullanılan çöktürme reaktifinin NiO/ZnO nanokompozit partikül üretimindeki etkisi incelenmiştir.