Browsing by Author "Erdem, Ilker"

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Influence of Silica Nanoparticles on the Stability of Paraffin Wax Emulsion
(Yildiz Technical Univ, 2023) Ibrahim, Aliu Pennah; Erdem, Ilker; Gonen, Mehmet
Paraffin wax emulsions have been used widely in various areas. However, the basic problem faced in all areas is instability of emulsion. Different methods and emulsifiers have been proposed to overcome this problem. This study focuses on using a commercial emulsifier, (IK8000) and aqueous silica nanoparticles to formulate paraffin wax emulsions and investigate their effects on the stability and mean diameter of paraffin wax emulsions. For comparison purpose, different emulsifier, PEG-7 Glyceryl Cocoate was used to stabilize one of 20 % (wt./ wt.) paraffin wax emulsions. The PEG-7-Glyceryl Cocoate stabilized emulsion phase -separated after 3 days while the IK-8000 stabilized remained stable for more than a month. The effect of the silica nanoparticles on the emulsion's stability was studied by observing samples stored for over 2 months. It was seen that aqueous silica nanoparticles helped to increase the stability of the paraffin wax emulsions. Emulsions prepared without silica nanoparticles (only IK-8000) were stable for just a month (1 month) whereas those which were formulated with silica nanoparticles and IK-8000 remained stable for more than 2 months (> 2 months). However, the addition of aqueous silica nanoparticles did not have a significant effect on the mean particle size of the emulsion. It was observed that the addition of 0.5 mL aqueous silica nanoparticles to the paraffin wax emulsion first increased the mean particle size from 1.142 mu m to 2.680 mu m. Nonetheless, further increasing the amount of the aqueous silica nanoparticles from 1.0-5.0 mL decreased the mean particles size of the paraffin wax emulsion from 2.680 mu m to 0.942 mu m. The contact angle formed by water drop on the surfaces coated with different emulsion samples of 30%wt. PWE, 40%wt. PWE, 50%wt. PWE and 60 %wt. PWE were measured. The higher the degree of solid content in emulsion, the greater the contact angle measured thus higher hydrophobicity.
Citation - WoS: 1
A Novel Bifunctional Organic Supported Nano-Titania Photocatalyst via the Sol-Gel Method Using Walnut-Shell
(Elsevier, 2026) Erdem, Ilker
Nano-structured photocatalytic titania was prepared via the sol-gel method on the surface of carbon-rich organic support in situ to be used as a supported photocatalyst. The preparation process was lean, including sol preparation, mixing and calcination (450 degrees C). The microstructure and crystallinity were characterized by using SEM and XRD analysis. The prepared photocatalytic material shows better water clarification (dye removal) efficiencies than commercial nano titania, either excited by UV or visible light, or kept in the darkness. A bifunctional composite having both photocatalysis and adsorption capabilities simultaneously was prepared using walnut shell (WNS) as organic support for the first time. It has considerably higher dye removal rates (kapp values (min(-1))) when compared with commercial nano titania: 0.1827 (2.83 times higher), 0.1188 (9.35 times higher) and 0.1066 (12.25 times higher) under UV light, under visible light, and in the darkness, respectively, making it a promising candidate for water clarification processes.
Citation - WoS: 1
Green Synthesis and Characterization of Zinc Oxide Nanoparticles via Thyme for Biomedical Applications: Effect of Plant Extract Concentration and Drying Method
(Springer, 2025) Karakaya, Humeyra; Kizilates, Burcu; Erdem, Ilker
Green synthesis of nano particles using plant extracts is sustainable, cost-effective, and eco-friendly. However, the synthesis parameters are still being investigated. In this study, zinc oxide nanoparticles (ZnO NPs) were prepared via thyme extract (green synthesis) and the effect of synthesis parameters were investigated. Samples with different concentrations of thyme plant extract (PE) (10, 16 & 24% (v/v) PE / Zn salt solution) were prepared and two different drying methods (freeze-drying (FD) and oven-drying (OD)) were performed. XRD results showed the hexagonal crystalline ZnO were formed with considerable crystallinity (70.8-75.1%) without further heat treatment (calcination). The crystallite sizes of ZnO NPs were determined to be in the range of 11.9-14.8 nm. The ZnO NPs prepared via PE concentration of 16% (v/v) and freeze-drying was with the finest crystallite size (11.9 nm) and considerable crystallinity (72.9%). ZnO NPs prepared via FD method were found to have smaller particle sizes, thus providing a higher surface-to-volume ratio. DLS (dynamic light scattering) analysis was used for determining the particle size distribution (PSD) and surface charge of ZnO NPs at acidic, neutral and basic pH values. The antibacterial characteristics of ZnO NPs were determined against Gram (+) and (-) bacteria. The ZnO NPs with the finest microstructure (16% PE (v/v), FD) had the highest antibacterial activity. The green synthesized ZnO NPs prepared in this study may be promising candidates for various applications including biomaterials and biomedical applications with their fine microstructure and considerable antibacterial activity.
Citation - WoS: 4
Citation - Scopus: 3
Modification of Surface Charge Characteristics for Unsupported Nanostructured Titania-Zirconia UF/NF Membrane Top Layers With Calcination Temperature
(Springer, 2020) Erdem, Ilker; Ciftcioglu, Muhsin
Ceramic membranes are more advantageous alternatives especially for harsh working conditions when compared with the polymeric membranes. The porous multilayer structure of the ceramic membranes (composed of support, intermediate, and top layers) can be prepared via different oxides. Titania and zirconia, having superior properties, are mainly preferred for the top layer formation. The separation properties of the membrane are both dependent on pore morphology and surface charge of the oxide(s) forming the top layer. The effect of surface charge in separation may be very significant in case of filtration of charged species with relatively lower mass as in the ultrafiltration (UF) and nanofiltration (NF). In this study, unsupported membrane top layers were prepared with varying titania/zirconia ratios by sol-gel technique. Their surface charges at different pH conditions after calcination at varying temperatures (400 degrees, 500 degrees, and 600 degrees C) were determined. The surface charge of the pure titania (full Ti) top layer was decreasing with the increasing calcination temperature. The highest magnitudes of zeta potential for both acidic and basic conditions were measured via Zr rich top layer (TiZr2575) at calcination temperatures >= 500 degrees C, which was composed of anatase, rutile (titania), and tetragonal (zirconia) phases after calcination. The tailor-made top layer can be prepared with modifications during membrane preparation.