Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği

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  • Article
    Citation - WoS: 2
    The Effect of the Temperature of Heat Treatment Process and the Concentration and Duration of Acid Leaching on the Size and Crystallinity of Nano-Silica Powders Formed by the Dissociation of Natural Diatom Frustule
    (American Scientific Publishers, 2022) Ülker, Sevkan; Güden, Mustafa
    The present study focused on the processing of nano-silica powders in varying sizes and crystallinities through IP: 846247.10 On: Wed, 14 Dec 2022 07:29:25 heat treatment (900-1200 degrees C), hydrofluoric acid leaching (1-7 N), and ball milling (1 h, 500 rpm) of natural Copyright American Scentfic P blishers diatom frustules. The starting natural frustules were determined to be composed of amorphous silica (88%) Delivered by Ingenta and quartz. The partially ordered crystalline low-quartz and or precursor to low-cristobalite started to form at-900 degrees C. As the heat treatment temperature increased, the crystallinity of the frustules increased from 9.3% at 25 degrees C to 46% at 1200 degrees C. Applying a ball milling reduced the mean particle sizes of the as-received and heat-treated frustules from 15.6-13.7 mu m to 7.2-6.7 mu m, respectively. Acid leaching of the as-received and heat-treated frustules resulted in a further increase in the crystallinity. Furthermore, a ball milling applied after an acid leaching was very effective in reducing the particle size of the as-received and heat-treated frustules. The mean particle size of the acid-leached frustules decreased to 774-547 nm with a crystallinity varying between 12 and 48% after ball milling. A partially dissolved amorphous phase was observed in between crystalline silica grains after acid leaching, which resulted in a rapid fracture/separation of the frustules in ball milling.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 2
    Preparation and Photocatalytic Performances of Zno Nanostructures: Effects of Anodization Voltage and Time
    (Wiley, 2022) Öksüz, Ahmet Emrecan; Yurddaşkal, Metin; Doluel, Eyyup Can; Kartal, Uğur; Dikici, Tuncay
    In this study, ZnO nanostructures with different morphologies were produced by varying anodizing parameters (time and voltage), and the photocatalytic activities of these structures were examined. ZnO nanostructures were fabricated through different voltage and duration consisting of nine samples with KHCO3 solution as an electrolyte. The produced ZnO nanostructures were investigated by using X-ray diffraction (XRD), scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–vis spectrophotometer. It was found that the morphology of ZnO was formed as nanosponge, nanoflower, nanowire, heterogeneous structures. ZnO nanostructures were identified by matching XRD peaks due to the ICDD database. Experiments on photocatalytic degradation of methylene blue demonstrated the photocatalytic activity of ZnO samples. The best photocatalytic performance of the samples was observed by S1 sample, which was anodized for 30 min in 0.05 M of KHCO3 electrolyte at 20 V, after 420 min exposure of the UV–vis light source with the degradation rate of 87.3%. Such ZnO nanostructures exhibit unique properties and have high potential for wastewater treatment.