Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 4Citation - Scopus: 4Optical and Photocatalytic Properties of Zno and Zns Structures Formed as Controlled Calcination Products of L-Cysteine Assisted Aqueous Precipitation(Elsevier, 2020) Şen, Selin; Top, AybenZnO and ZnS structures were obtained by the calcination of the aqueous precipitation products of Zn(NO3)2, NaOH and L-cysteine (Cys). Initial Cys:Zn molar ratios were changed as 0.1:1, 0.5:1, 1:1 and 1.5:1. All the precursors were transformed into ZnO upon calcination at 700 °C. ZnS structures were obtained by calcining the precursors prepared at the Cys:Zn ratios of 1 and 1.5 at 350 °C. In addition to changing chemical composition of the precipitation products, calcination temperature and initial Cys:Zn ratio also affected morphology, surface area, photoluminescence and photocatalytic properties of the final products. Free exciton energy values of the ZnO samples were observed to be between 3.29 eV and 3.35 eV. PL spectra of the ZnO samples indicated blue and green emission centers. Zinc interstitials (Zni), revealed by the blue emissions in the PL spectra were also confirmed by Auger Zn L3M4.5M4.5 spectra. The samples calcined at 350 °C removed rhodamine B mainly by adsorption. All the samples calcined at 700 °C successfully degraded the dye under UV light. Among the samples calcined at 700 °C, ZnO sample prepared at Cys:Zn = 0.5, which has the highest surface area and unique photoluminescence spectrum exhibited the fastest photodegradation rate. © 2020 Elsevier LtdArticle Citation - WoS: 10Citation - Scopus: 13Effect of Supercritical Ethanol Drying on the Properties of Zinc Oxide Nanoparticles(Taylor and Francis Ltd., 2012) Egbuchunam, Theresa; Balköse, DevrimThe synthesis, characterization, and application as polymers and anti-wear additives of nanosized zinc oxide particles obtained by conventional and supercritical ethanol drying are reported in this study. The nanaoparticles of ZnO produced by the two different drying techniques were characterized using Fourier Transform Infrared (FT-IR) spectrophotometry, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Thermogravimetric analysis (TGA) to elucidate the shape, size, composition, and stability of the nanoparticles. ZnO nanoparticles were then applied to poly (vinyl chloride) (PVC) powder and light mineral oil to assess their effectiveness and suitability as additives in diverse areas. XRD analysis revealed ZnO crystalline structure with average particle size of 24.7 nm for zinc oxide nanoparticles prepared by supercritical ethanol drying while SEM showed well-isolated and monodisperse particles with average size of 61.08 nm. © 2012 Copyright Taylor and Francis Group, LLC.